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llvm-project/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

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//===- DAGCombiner.cpp - Implement a DAG node combiner --------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This pass combines dag nodes to form fewer, simpler DAG nodes. It can be run
// both before and after the DAG is legalized.
//
// This pass is not a substitute for the LLVM IR instcombine pass. This pass is
// primarily intended to handle simplification opportunities that are implicit
// in the LLVM IR and exposed by the various codegen lowering phases.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/IntervalMap.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/MemoryLocation.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/CodeGen/DAGCombine.h"
#include "llvm/CodeGen/ISDOpcodes.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/RuntimeLibcalls.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/SelectionDAGAddressAnalysis.h"
#include "llvm/CodeGen/SelectionDAGNodes.h"
#include "llvm/CodeGen/SelectionDAGTargetInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Metadata.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/MachineValueType.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <functional>
#include <iterator>
#include <string>
#include <tuple>
#include <utility>
using namespace llvm;
#define DEBUG_TYPE "dagcombine"
STATISTIC(NodesCombined , "Number of dag nodes combined");
STATISTIC(PreIndexedNodes , "Number of pre-indexed nodes created");
STATISTIC(PostIndexedNodes, "Number of post-indexed nodes created");
STATISTIC(OpsNarrowed , "Number of load/op/store narrowed");
STATISTIC(LdStFP2Int , "Number of fp load/store pairs transformed to int");
STATISTIC(SlicedLoads, "Number of load sliced");
STATISTIC(NumFPLogicOpsConv, "Number of logic ops converted to fp ops");
static cl::opt<bool>
CombinerGlobalAA("combiner-global-alias-analysis", cl::Hidden,
cl::desc("Enable DAG combiner's use of IR alias analysis"));
static cl::opt<bool>
UseTBAA("combiner-use-tbaa", cl::Hidden, cl::init(true),
cl::desc("Enable DAG combiner's use of TBAA"));
#ifndef NDEBUG
static cl::opt<std::string>
CombinerAAOnlyFunc("combiner-aa-only-func", cl::Hidden,
cl::desc("Only use DAG-combiner alias analysis in this"
" function"));
#endif
/// Hidden option to stress test load slicing, i.e., when this option
/// is enabled, load slicing bypasses most of its profitability guards.
static cl::opt<bool>
StressLoadSlicing("combiner-stress-load-slicing", cl::Hidden,
cl::desc("Bypass the profitability model of load slicing"),
cl::init(false));
static cl::opt<bool>
MaySplitLoadIndex("combiner-split-load-index", cl::Hidden, cl::init(true),
cl::desc("DAG combiner may split indexing from loads"));
static cl::opt<bool>
EnableStoreMerging("combiner-store-merging", cl::Hidden, cl::init(true),
cl::desc("DAG combiner enable merging multiple stores "
"into a wider store"));
static cl::opt<unsigned> TokenFactorInlineLimit(
"combiner-tokenfactor-inline-limit", cl::Hidden, cl::init(2048),
cl::desc("Limit the number of operands to inline for Token Factors"));
static cl::opt<unsigned> StoreMergeDependenceLimit(
"combiner-store-merge-dependence-limit", cl::Hidden, cl::init(10),
cl::desc("Limit the number of times for the same StoreNode and RootNode "
"to bail out in store merging dependence check"));
static cl::opt<bool> EnableReduceLoadOpStoreWidth(
"combiner-reduce-load-op-store-width", cl::Hidden, cl::init(true),
cl::desc("DAG combiner enable reducing the width of load/op/store "
"sequence"));
static cl::opt<bool> EnableShrinkLoadReplaceStoreWithStore(
"combiner-shrink-load-replace-store-with-store", cl::Hidden, cl::init(true),
cl::desc("DAG combiner enable load/<replace bytes>/store with "
"a narrower store"));
namespace {
class DAGCombiner {
SelectionDAG &DAG;
const TargetLowering &TLI;
const SelectionDAGTargetInfo *STI;
CombineLevel Level = BeforeLegalizeTypes;
CodeGenOpt::Level OptLevel;
bool LegalDAG = false;
bool LegalOperations = false;
bool LegalTypes = false;
bool ForCodeSize;
bool DisableGenericCombines;
/// Worklist of all of the nodes that need to be simplified.
///
/// This must behave as a stack -- new nodes to process are pushed onto the
/// back and when processing we pop off of the back.
///
/// The worklist will not contain duplicates but may contain null entries
/// due to nodes being deleted from the underlying DAG.
SmallVector<SDNode *, 64> Worklist;
/// Mapping from an SDNode to its position on the worklist.
///
/// This is used to find and remove nodes from the worklist (by nulling
/// them) when they are deleted from the underlying DAG. It relies on
/// stable indices of nodes within the worklist.
DenseMap<SDNode *, unsigned> WorklistMap;
/// This records all nodes attempted to add to the worklist since we
/// considered a new worklist entry. As we keep do not add duplicate nodes
/// in the worklist, this is different from the tail of the worklist.
SmallSetVector<SDNode *, 32> PruningList;
/// Set of nodes which have been combined (at least once).
///
/// This is used to allow us to reliably add any operands of a DAG node
/// which have not yet been combined to the worklist.
SmallPtrSet<SDNode *, 32> CombinedNodes;
/// Map from candidate StoreNode to the pair of RootNode and count.
/// The count is used to track how many times we have seen the StoreNode
/// with the same RootNode bail out in dependence check. If we have seen
/// the bail out for the same pair many times over a limit, we won't
/// consider the StoreNode with the same RootNode as store merging
/// candidate again.
DenseMap<SDNode *, std::pair<SDNode *, unsigned>> StoreRootCountMap;
// AA - Used for DAG load/store alias analysis.
AliasAnalysis *AA;
/// When an instruction is simplified, add all users of the instruction to
/// the work lists because they might get more simplified now.
void AddUsersToWorklist(SDNode *N) {
for (SDNode *Node : N->uses())
AddToWorklist(Node);
}
/// Convenient shorthand to add a node and all of its user to the worklist.
void AddToWorklistWithUsers(SDNode *N) {
AddUsersToWorklist(N);
AddToWorklist(N);
}
// Prune potentially dangling nodes. This is called after
// any visit to a node, but should also be called during a visit after any
// failed combine which may have created a DAG node.
void clearAddedDanglingWorklistEntries() {
// Check any nodes added to the worklist to see if they are prunable.
while (!PruningList.empty()) {
auto *N = PruningList.pop_back_val();
if (N->use_empty())
recursivelyDeleteUnusedNodes(N);
}
}
SDNode *getNextWorklistEntry() {
// Before we do any work, remove nodes that are not in use.
clearAddedDanglingWorklistEntries();
SDNode *N = nullptr;
// The Worklist holds the SDNodes in order, but it may contain null
// entries.
while (!N && !Worklist.empty()) {
N = Worklist.pop_back_val();
}
if (N) {
bool GoodWorklistEntry = WorklistMap.erase(N);
(void)GoodWorklistEntry;
assert(GoodWorklistEntry &&
"Found a worklist entry without a corresponding map entry!");
}
return N;
}
/// Call the node-specific routine that folds each particular type of node.
SDValue visit(SDNode *N);
public:
DAGCombiner(SelectionDAG &D, AliasAnalysis *AA, CodeGenOpt::Level OL)
: DAG(D), TLI(D.getTargetLoweringInfo()),
STI(D.getSubtarget().getSelectionDAGInfo()), OptLevel(OL), AA(AA) {
ForCodeSize = DAG.shouldOptForSize();
DisableGenericCombines = STI && STI->disableGenericCombines(OptLevel);
MaximumLegalStoreInBits = 0;
// We use the minimum store size here, since that's all we can guarantee
// for the scalable vector types.
for (MVT VT : MVT::all_valuetypes())
if (EVT(VT).isSimple() && VT != MVT::Other &&
TLI.isTypeLegal(EVT(VT)) &&
VT.getSizeInBits().getKnownMinSize() >= MaximumLegalStoreInBits)
MaximumLegalStoreInBits = VT.getSizeInBits().getKnownMinSize();
}
void ConsiderForPruning(SDNode *N) {
// Mark this for potential pruning.
PruningList.insert(N);
}
/// Add to the worklist making sure its instance is at the back (next to be
/// processed.)
void AddToWorklist(SDNode *N) {
assert(N->getOpcode() != ISD::DELETED_NODE &&
"Deleted Node added to Worklist");
// Skip handle nodes as they can't usefully be combined and confuse the
// zero-use deletion strategy.
if (N->getOpcode() == ISD::HANDLENODE)
return;
ConsiderForPruning(N);
if (WorklistMap.insert(std::make_pair(N, Worklist.size())).second)
Worklist.push_back(N);
}
/// Remove all instances of N from the worklist.
void removeFromWorklist(SDNode *N) {
CombinedNodes.erase(N);
PruningList.remove(N);
StoreRootCountMap.erase(N);
auto It = WorklistMap.find(N);
if (It == WorklistMap.end())
return; // Not in the worklist.
// Null out the entry rather than erasing it to avoid a linear operation.
Worklist[It->second] = nullptr;
WorklistMap.erase(It);
}
void deleteAndRecombine(SDNode *N);
bool recursivelyDeleteUnusedNodes(SDNode *N);
/// Replaces all uses of the results of one DAG node with new values.
SDValue CombineTo(SDNode *N, const SDValue *To, unsigned NumTo,
bool AddTo = true);
/// Replaces all uses of the results of one DAG node with new values.
SDValue CombineTo(SDNode *N, SDValue Res, bool AddTo = true) {
return CombineTo(N, &Res, 1, AddTo);
}
/// Replaces all uses of the results of one DAG node with new values.
SDValue CombineTo(SDNode *N, SDValue Res0, SDValue Res1,
bool AddTo = true) {
SDValue To[] = { Res0, Res1 };
return CombineTo(N, To, 2, AddTo);
}
void CommitTargetLoweringOpt(const TargetLowering::TargetLoweringOpt &TLO);
private:
unsigned MaximumLegalStoreInBits;
/// Check the specified integer node value to see if it can be simplified or
/// if things it uses can be simplified by bit propagation.
/// If so, return true.
bool SimplifyDemandedBits(SDValue Op) {
unsigned BitWidth = Op.getScalarValueSizeInBits();
APInt DemandedBits = APInt::getAllOnes(BitWidth);
return SimplifyDemandedBits(Op, DemandedBits);
}
bool SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits) {
TargetLowering::TargetLoweringOpt TLO(DAG, LegalTypes, LegalOperations);
KnownBits Known;
if (!TLI.SimplifyDemandedBits(Op, DemandedBits, Known, TLO, 0, false))
return false;
// Revisit the node.
AddToWorklist(Op.getNode());
CommitTargetLoweringOpt(TLO);
return true;
}
/// Check the specified vector node value to see if it can be simplified or
/// if things it uses can be simplified as it only uses some of the
/// elements. If so, return true.
bool SimplifyDemandedVectorElts(SDValue Op) {
// TODO: For now just pretend it cannot be simplified.
if (Op.getValueType().isScalableVector())
return false;
unsigned NumElts = Op.getValueType().getVectorNumElements();
APInt DemandedElts = APInt::getAllOnes(NumElts);
return SimplifyDemandedVectorElts(Op, DemandedElts);
}
bool SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
const APInt &DemandedElts,
bool AssumeSingleUse = false);
bool SimplifyDemandedVectorElts(SDValue Op, const APInt &DemandedElts,
bool AssumeSingleUse = false);
bool CombineToPreIndexedLoadStore(SDNode *N);
bool CombineToPostIndexedLoadStore(SDNode *N);
SDValue SplitIndexingFromLoad(LoadSDNode *LD);
bool SliceUpLoad(SDNode *N);
// Scalars have size 0 to distinguish from singleton vectors.
SDValue ForwardStoreValueToDirectLoad(LoadSDNode *LD);
bool getTruncatedStoreValue(StoreSDNode *ST, SDValue &Val);
bool extendLoadedValueToExtension(LoadSDNode *LD, SDValue &Val);
/// Replace an ISD::EXTRACT_VECTOR_ELT of a load with a narrowed
/// load.
///
/// \param EVE ISD::EXTRACT_VECTOR_ELT to be replaced.
/// \param InVecVT type of the input vector to EVE with bitcasts resolved.
/// \param EltNo index of the vector element to load.
/// \param OriginalLoad load that EVE came from to be replaced.
/// \returns EVE on success SDValue() on failure.
SDValue scalarizeExtractedVectorLoad(SDNode *EVE, EVT InVecVT,
SDValue EltNo,
LoadSDNode *OriginalLoad);
void ReplaceLoadWithPromotedLoad(SDNode *Load, SDNode *ExtLoad);
SDValue PromoteOperand(SDValue Op, EVT PVT, bool &Replace);
SDValue SExtPromoteOperand(SDValue Op, EVT PVT);
SDValue ZExtPromoteOperand(SDValue Op, EVT PVT);
SDValue PromoteIntBinOp(SDValue Op);
SDValue PromoteIntShiftOp(SDValue Op);
SDValue PromoteExtend(SDValue Op);
bool PromoteLoad(SDValue Op);
/// Call the node-specific routine that knows how to fold each
/// particular type of node. If that doesn't do anything, try the
/// target-specific DAG combines.
SDValue combine(SDNode *N);
// Visitation implementation - Implement dag node combining for different
// node types. The semantics are as follows:
// Return Value:
// SDValue.getNode() == 0 - No change was made
// SDValue.getNode() == N - N was replaced, is dead and has been handled.
// otherwise - N should be replaced by the returned Operand.
//
SDValue visitTokenFactor(SDNode *N);
SDValue visitMERGE_VALUES(SDNode *N);
SDValue visitADD(SDNode *N);
SDValue visitADDLike(SDNode *N);
SDValue visitADDLikeCommutative(SDValue N0, SDValue N1, SDNode *LocReference);
SDValue visitSUB(SDNode *N);
SDValue visitADDSAT(SDNode *N);
SDValue visitSUBSAT(SDNode *N);
SDValue visitADDC(SDNode *N);
SDValue visitADDO(SDNode *N);
SDValue visitUADDOLike(SDValue N0, SDValue N1, SDNode *N);
SDValue visitSUBC(SDNode *N);
SDValue visitSUBO(SDNode *N);
SDValue visitADDE(SDNode *N);
SDValue visitADDCARRY(SDNode *N);
SDValue visitSADDO_CARRY(SDNode *N);
SDValue visitADDCARRYLike(SDValue N0, SDValue N1, SDValue CarryIn, SDNode *N);
SDValue visitSUBE(SDNode *N);
SDValue visitSUBCARRY(SDNode *N);
SDValue visitSSUBO_CARRY(SDNode *N);
SDValue visitMUL(SDNode *N);
SDValue visitMULFIX(SDNode *N);
SDValue useDivRem(SDNode *N);
SDValue visitSDIV(SDNode *N);
SDValue visitSDIVLike(SDValue N0, SDValue N1, SDNode *N);
SDValue visitUDIV(SDNode *N);
SDValue visitUDIVLike(SDValue N0, SDValue N1, SDNode *N);
SDValue visitREM(SDNode *N);
SDValue visitMULHU(SDNode *N);
SDValue visitMULHS(SDNode *N);
SDValue visitAVG(SDNode *N);
SDValue visitSMUL_LOHI(SDNode *N);
SDValue visitUMUL_LOHI(SDNode *N);
SDValue visitMULO(SDNode *N);
SDValue visitIMINMAX(SDNode *N);
SDValue visitAND(SDNode *N);
SDValue visitANDLike(SDValue N0, SDValue N1, SDNode *N);
SDValue visitOR(SDNode *N);
SDValue visitORLike(SDValue N0, SDValue N1, SDNode *N);
SDValue visitXOR(SDNode *N);
SDValue SimplifyVBinOp(SDNode *N, const SDLoc &DL);
SDValue visitSHL(SDNode *N);
SDValue visitSRA(SDNode *N);
SDValue visitSRL(SDNode *N);
SDValue visitFunnelShift(SDNode *N);
SDValue visitSHLSAT(SDNode *N);
SDValue visitRotate(SDNode *N);
SDValue visitABS(SDNode *N);
SDValue visitBSWAP(SDNode *N);
SDValue visitBITREVERSE(SDNode *N);
SDValue visitCTLZ(SDNode *N);
SDValue visitCTLZ_ZERO_UNDEF(SDNode *N);
SDValue visitCTTZ(SDNode *N);
SDValue visitCTTZ_ZERO_UNDEF(SDNode *N);
SDValue visitCTPOP(SDNode *N);
SDValue visitSELECT(SDNode *N);
SDValue visitVSELECT(SDNode *N);
SDValue visitSELECT_CC(SDNode *N);
SDValue visitSETCC(SDNode *N);
SDValue visitSETCCCARRY(SDNode *N);
SDValue visitSIGN_EXTEND(SDNode *N);
SDValue visitZERO_EXTEND(SDNode *N);
SDValue visitANY_EXTEND(SDNode *N);
SDValue visitAssertExt(SDNode *N);
SDValue visitAssertAlign(SDNode *N);
SDValue visitSIGN_EXTEND_INREG(SDNode *N);
SDValue visitEXTEND_VECTOR_INREG(SDNode *N);
SDValue visitTRUNCATE(SDNode *N);
SDValue visitBITCAST(SDNode *N);
SDValue visitFREEZE(SDNode *N);
SDValue visitBUILD_PAIR(SDNode *N);
SDValue visitFADD(SDNode *N);
SDValue visitSTRICT_FADD(SDNode *N);
SDValue visitFSUB(SDNode *N);
SDValue visitFMUL(SDNode *N);
SDValue visitFMA(SDNode *N);
SDValue visitFDIV(SDNode *N);
SDValue visitFREM(SDNode *N);
SDValue visitFSQRT(SDNode *N);
SDValue visitFCOPYSIGN(SDNode *N);
SDValue visitFPOW(SDNode *N);
SDValue visitSINT_TO_FP(SDNode *N);
SDValue visitUINT_TO_FP(SDNode *N);
SDValue visitFP_TO_SINT(SDNode *N);
SDValue visitFP_TO_UINT(SDNode *N);
SDValue visitFP_ROUND(SDNode *N);
SDValue visitFP_EXTEND(SDNode *N);
SDValue visitFNEG(SDNode *N);
SDValue visitFABS(SDNode *N);
SDValue visitFCEIL(SDNode *N);
SDValue visitFTRUNC(SDNode *N);
SDValue visitFFLOOR(SDNode *N);
SDValue visitFMinMax(SDNode *N);
SDValue visitBRCOND(SDNode *N);
SDValue visitBR_CC(SDNode *N);
SDValue visitLOAD(SDNode *N);
SDValue replaceStoreChain(StoreSDNode *ST, SDValue BetterChain);
SDValue replaceStoreOfFPConstant(StoreSDNode *ST);
SDValue visitSTORE(SDNode *N);
SDValue visitLIFETIME_END(SDNode *N);
SDValue visitINSERT_VECTOR_ELT(SDNode *N);
SDValue visitEXTRACT_VECTOR_ELT(SDNode *N);
SDValue visitBUILD_VECTOR(SDNode *N);
SDValue visitCONCAT_VECTORS(SDNode *N);
SDValue visitEXTRACT_SUBVECTOR(SDNode *N);
SDValue visitVECTOR_SHUFFLE(SDNode *N);
SDValue visitSCALAR_TO_VECTOR(SDNode *N);
SDValue visitINSERT_SUBVECTOR(SDNode *N);
SDValue visitMLOAD(SDNode *N);
SDValue visitMSTORE(SDNode *N);
SDValue visitMGATHER(SDNode *N);
SDValue visitMSCATTER(SDNode *N);
SDValue visitFP_TO_FP16(SDNode *N);
SDValue visitFP16_TO_FP(SDNode *N);
SDValue visitFP_TO_BF16(SDNode *N);
SDValue visitVECREDUCE(SDNode *N);
SDValue visitVPOp(SDNode *N);
SDValue visitFADDForFMACombine(SDNode *N);
SDValue visitFSUBForFMACombine(SDNode *N);
SDValue visitFMULForFMADistributiveCombine(SDNode *N);
SDValue XformToShuffleWithZero(SDNode *N);
bool reassociationCanBreakAddressingModePattern(unsigned Opc,
const SDLoc &DL,
SDNode *N,
SDValue N0,
SDValue N1);
SDValue reassociateOpsCommutative(unsigned Opc, const SDLoc &DL, SDValue N0,
SDValue N1);
SDValue reassociateOps(unsigned Opc, const SDLoc &DL, SDValue N0,
SDValue N1, SDNodeFlags Flags);
SDValue visitShiftByConstant(SDNode *N);
SDValue foldSelectOfConstants(SDNode *N);
SDValue foldVSelectOfConstants(SDNode *N);
SDValue foldBinOpIntoSelect(SDNode *BO);
bool SimplifySelectOps(SDNode *SELECT, SDValue LHS, SDValue RHS);
SDValue hoistLogicOpWithSameOpcodeHands(SDNode *N);
SDValue SimplifySelect(const SDLoc &DL, SDValue N0, SDValue N1, SDValue N2);
SDValue SimplifySelectCC(const SDLoc &DL, SDValue N0, SDValue N1,
SDValue N2, SDValue N3, ISD::CondCode CC,
bool NotExtCompare = false);
SDValue convertSelectOfFPConstantsToLoadOffset(
const SDLoc &DL, SDValue N0, SDValue N1, SDValue N2, SDValue N3,
ISD::CondCode CC);
SDValue foldSignChangeInBitcast(SDNode *N);
SDValue foldSelectCCToShiftAnd(const SDLoc &DL, SDValue N0, SDValue N1,
SDValue N2, SDValue N3, ISD::CondCode CC);
SDValue foldSelectOfBinops(SDNode *N);
SDValue foldSextSetcc(SDNode *N);
SDValue foldLogicOfSetCCs(bool IsAnd, SDValue N0, SDValue N1,
const SDLoc &DL);
SDValue foldSubToUSubSat(EVT DstVT, SDNode *N);
SDValue unfoldMaskedMerge(SDNode *N);
SDValue unfoldExtremeBitClearingToShifts(SDNode *N);
SDValue SimplifySetCC(EVT VT, SDValue N0, SDValue N1, ISD::CondCode Cond,
const SDLoc &DL, bool foldBooleans);
SDValue rebuildSetCC(SDValue N);
bool isSetCCEquivalent(SDValue N, SDValue &LHS, SDValue &RHS,
SDValue &CC, bool MatchStrict = false) const;
bool isOneUseSetCC(SDValue N) const;
SDValue SimplifyNodeWithTwoResults(SDNode *N, unsigned LoOp,
unsigned HiOp);
SDValue CombineConsecutiveLoads(SDNode *N, EVT VT);
SDValue CombineExtLoad(SDNode *N);
SDValue CombineZExtLogicopShiftLoad(SDNode *N);
SDValue combineRepeatedFPDivisors(SDNode *N);
SDValue combineInsertEltToShuffle(SDNode *N, unsigned InsIndex);
SDValue ConstantFoldBITCASTofBUILD_VECTOR(SDNode *, EVT);
SDValue BuildSDIV(SDNode *N);
SDValue BuildSDIVPow2(SDNode *N);
SDValue BuildUDIV(SDNode *N);
SDValue BuildSREMPow2(SDNode *N);
SDValue buildOptimizedSREM(SDValue N0, SDValue N1, SDNode *N);
SDValue BuildLogBase2(SDValue V, const SDLoc &DL);
SDValue BuildDivEstimate(SDValue N, SDValue Op, SDNodeFlags Flags);
SDValue buildRsqrtEstimate(SDValue Op, SDNodeFlags Flags);
SDValue buildSqrtEstimate(SDValue Op, SDNodeFlags Flags);
SDValue buildSqrtEstimateImpl(SDValue Op, SDNodeFlags Flags, bool Recip);
SDValue buildSqrtNROneConst(SDValue Arg, SDValue Est, unsigned Iterations,
SDNodeFlags Flags, bool Reciprocal);
SDValue buildSqrtNRTwoConst(SDValue Arg, SDValue Est, unsigned Iterations,
SDNodeFlags Flags, bool Reciprocal);
SDValue MatchBSwapHWordLow(SDNode *N, SDValue N0, SDValue N1,
bool DemandHighBits = true);
SDValue MatchBSwapHWord(SDNode *N, SDValue N0, SDValue N1);
SDValue MatchRotatePosNeg(SDValue Shifted, SDValue Pos, SDValue Neg,
SDValue InnerPos, SDValue InnerNeg, bool HasPos,
unsigned PosOpcode, unsigned NegOpcode,
const SDLoc &DL);
SDValue MatchFunnelPosNeg(SDValue N0, SDValue N1, SDValue Pos, SDValue Neg,
SDValue InnerPos, SDValue InnerNeg, bool HasPos,
unsigned PosOpcode, unsigned NegOpcode,
const SDLoc &DL);
SDValue MatchRotate(SDValue LHS, SDValue RHS, const SDLoc &DL);
SDValue MatchLoadCombine(SDNode *N);
SDValue mergeTruncStores(StoreSDNode *N);
SDValue reduceLoadWidth(SDNode *N);
SDValue ReduceLoadOpStoreWidth(SDNode *N);
SDValue splitMergedValStore(StoreSDNode *ST);
SDValue TransformFPLoadStorePair(SDNode *N);
SDValue convertBuildVecZextToZext(SDNode *N);
SDValue reduceBuildVecExtToExtBuildVec(SDNode *N);
SDValue reduceBuildVecTruncToBitCast(SDNode *N);
SDValue reduceBuildVecToShuffle(SDNode *N);
SDValue createBuildVecShuffle(const SDLoc &DL, SDNode *N,
ArrayRef<int> VectorMask, SDValue VecIn1,
SDValue VecIn2, unsigned LeftIdx,
bool DidSplitVec);
SDValue matchVSelectOpSizesWithSetCC(SDNode *Cast);
/// Walk up chain skipping non-aliasing memory nodes,
/// looking for aliasing nodes and adding them to the Aliases vector.
void GatherAllAliases(SDNode *N, SDValue OriginalChain,
SmallVectorImpl<SDValue> &Aliases);
/// Return true if there is any possibility that the two addresses overlap.
bool mayAlias(SDNode *Op0, SDNode *Op1) const;
/// Walk up chain skipping non-aliasing memory nodes, looking for a better
/// chain (aliasing node.)
SDValue FindBetterChain(SDNode *N, SDValue Chain);
/// Try to replace a store and any possibly adjacent stores on
/// consecutive chains with better chains. Return true only if St is
/// replaced.
///
/// Notice that other chains may still be replaced even if the function
/// returns false.
bool findBetterNeighborChains(StoreSDNode *St);
// Helper for findBetterNeighborChains. Walk up store chain add additional
// chained stores that do not overlap and can be parallelized.
bool parallelizeChainedStores(StoreSDNode *St);
/// Holds a pointer to an LSBaseSDNode as well as information on where it
/// is located in a sequence of memory operations connected by a chain.
struct MemOpLink {
// Ptr to the mem node.
LSBaseSDNode *MemNode;
// Offset from the base ptr.
int64_t OffsetFromBase;
MemOpLink(LSBaseSDNode *N, int64_t Offset)
: MemNode(N), OffsetFromBase(Offset) {}
};
// Classify the origin of a stored value.
enum class StoreSource { Unknown, Constant, Extract, Load };
StoreSource getStoreSource(SDValue StoreVal) {
switch (StoreVal.getOpcode()) {
case ISD::Constant:
case ISD::ConstantFP:
return StoreSource::Constant;
case ISD::EXTRACT_VECTOR_ELT:
case ISD::EXTRACT_SUBVECTOR:
return StoreSource::Extract;
case ISD::LOAD:
return StoreSource::Load;
default:
return StoreSource::Unknown;
}
}
/// This is a helper function for visitMUL to check the profitability
/// of folding (mul (add x, c1), c2) -> (add (mul x, c2), c1*c2).
/// MulNode is the original multiply, AddNode is (add x, c1),
/// and ConstNode is c2.
bool isMulAddWithConstProfitable(SDNode *MulNode, SDValue AddNode,
SDValue ConstNode);
/// This is a helper function for visitAND and visitZERO_EXTEND. Returns
/// true if the (and (load x) c) pattern matches an extload. ExtVT returns
/// the type of the loaded value to be extended.
bool isAndLoadExtLoad(ConstantSDNode *AndC, LoadSDNode *LoadN,
EVT LoadResultTy, EVT &ExtVT);
/// Helper function to calculate whether the given Load/Store can have its
/// width reduced to ExtVT.
bool isLegalNarrowLdSt(LSBaseSDNode *LDSTN, ISD::LoadExtType ExtType,
EVT &MemVT, unsigned ShAmt = 0);
/// Used by BackwardsPropagateMask to find suitable loads.
bool SearchForAndLoads(SDNode *N, SmallVectorImpl<LoadSDNode*> &Loads,
SmallPtrSetImpl<SDNode*> &NodesWithConsts,
ConstantSDNode *Mask, SDNode *&NodeToMask);
/// Attempt to propagate a given AND node back to load leaves so that they
/// can be combined into narrow loads.
bool BackwardsPropagateMask(SDNode *N);
/// Helper function for mergeConsecutiveStores which merges the component
/// store chains.
SDValue getMergeStoreChains(SmallVectorImpl<MemOpLink> &StoreNodes,
unsigned NumStores);
/// This is a helper function for mergeConsecutiveStores. When the source
/// elements of the consecutive stores are all constants or all extracted
/// vector elements, try to merge them into one larger store introducing
/// bitcasts if necessary. \return True if a merged store was created.
bool mergeStoresOfConstantsOrVecElts(SmallVectorImpl<MemOpLink> &StoreNodes,
EVT MemVT, unsigned NumStores,
bool IsConstantSrc, bool UseVector,
bool UseTrunc);
/// This is a helper function for mergeConsecutiveStores. Stores that
/// potentially may be merged with St are placed in StoreNodes. RootNode is
/// a chain predecessor to all store candidates.
void getStoreMergeCandidates(StoreSDNode *St,
SmallVectorImpl<MemOpLink> &StoreNodes,
SDNode *&Root);
/// Helper function for mergeConsecutiveStores. Checks if candidate stores
/// have indirect dependency through their operands. RootNode is the
/// predecessor to all stores calculated by getStoreMergeCandidates and is
/// used to prune the dependency check. \return True if safe to merge.
bool checkMergeStoreCandidatesForDependencies(
SmallVectorImpl<MemOpLink> &StoreNodes, unsigned NumStores,
SDNode *RootNode);
/// This is a helper function for mergeConsecutiveStores. Given a list of
/// store candidates, find the first N that are consecutive in memory.
/// Returns 0 if there are not at least 2 consecutive stores to try merging.
unsigned getConsecutiveStores(SmallVectorImpl<MemOpLink> &StoreNodes,
int64_t ElementSizeBytes) const;
/// This is a helper function for mergeConsecutiveStores. It is used for
/// store chains that are composed entirely of constant values.
bool tryStoreMergeOfConstants(SmallVectorImpl<MemOpLink> &StoreNodes,
unsigned NumConsecutiveStores,
EVT MemVT, SDNode *Root, bool AllowVectors);
/// This is a helper function for mergeConsecutiveStores. It is used for
/// store chains that are composed entirely of extracted vector elements.
/// When extracting multiple vector elements, try to store them in one
/// vector store rather than a sequence of scalar stores.
bool tryStoreMergeOfExtracts(SmallVectorImpl<MemOpLink> &StoreNodes,
unsigned NumConsecutiveStores, EVT MemVT,
SDNode *Root);
/// This is a helper function for mergeConsecutiveStores. It is used for
/// store chains that are composed entirely of loaded values.
bool tryStoreMergeOfLoads(SmallVectorImpl<MemOpLink> &StoreNodes,
unsigned NumConsecutiveStores, EVT MemVT,
SDNode *Root, bool AllowVectors,
bool IsNonTemporalStore, bool IsNonTemporalLoad);
/// Merge consecutive store operations into a wide store.
/// This optimization uses wide integers or vectors when possible.
/// \return true if stores were merged.
bool mergeConsecutiveStores(StoreSDNode *St);
/// Try to transform a truncation where C is a constant:
/// (trunc (and X, C)) -> (and (trunc X), (trunc C))
///
/// \p N needs to be a truncation and its first operand an AND. Other
/// requirements are checked by the function (e.g. that trunc is
/// single-use) and if missed an empty SDValue is returned.
SDValue distributeTruncateThroughAnd(SDNode *N);
/// Helper function to determine whether the target supports operation
/// given by \p Opcode for type \p VT, that is, whether the operation
/// is legal or custom before legalizing operations, and whether is
/// legal (but not custom) after legalization.
bool hasOperation(unsigned Opcode, EVT VT) {
return TLI.isOperationLegalOrCustom(Opcode, VT, LegalOperations);
}
public:
/// Runs the dag combiner on all nodes in the work list
void Run(CombineLevel AtLevel);
SelectionDAG &getDAG() const { return DAG; }
/// Returns a type large enough to hold any valid shift amount - before type
/// legalization these can be huge.
EVT getShiftAmountTy(EVT LHSTy) {
assert(LHSTy.isInteger() && "Shift amount is not an integer type!");
return TLI.getShiftAmountTy(LHSTy, DAG.getDataLayout(), LegalTypes);
}
/// This method returns true if we are running before type legalization or
/// if the specified VT is legal.
bool isTypeLegal(const EVT &VT) {
if (!LegalTypes) return true;
return TLI.isTypeLegal(VT);
}
/// Convenience wrapper around TargetLowering::getSetCCResultType
EVT getSetCCResultType(EVT VT) const {
return TLI.getSetCCResultType(DAG.getDataLayout(), *DAG.getContext(), VT);
}
void ExtendSetCCUses(const SmallVectorImpl<SDNode *> &SetCCs,
SDValue OrigLoad, SDValue ExtLoad,
ISD::NodeType ExtType);
};
/// This class is a DAGUpdateListener that removes any deleted
/// nodes from the worklist.
class WorklistRemover : public SelectionDAG::DAGUpdateListener {
DAGCombiner &DC;
public:
explicit WorklistRemover(DAGCombiner &dc)
: SelectionDAG::DAGUpdateListener(dc.getDAG()), DC(dc) {}
void NodeDeleted(SDNode *N, SDNode *E) override {
DC.removeFromWorklist(N);
}
};
class WorklistInserter : public SelectionDAG::DAGUpdateListener {
DAGCombiner &DC;
public:
explicit WorklistInserter(DAGCombiner &dc)
: SelectionDAG::DAGUpdateListener(dc.getDAG()), DC(dc) {}
// FIXME: Ideally we could add N to the worklist, but this causes exponential
// compile time costs in large DAGs, e.g. Halide.
void NodeInserted(SDNode *N) override { DC.ConsiderForPruning(N); }
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// TargetLowering::DAGCombinerInfo implementation
//===----------------------------------------------------------------------===//
void TargetLowering::DAGCombinerInfo::AddToWorklist(SDNode *N) {
((DAGCombiner*)DC)->AddToWorklist(N);
}
SDValue TargetLowering::DAGCombinerInfo::
CombineTo(SDNode *N, ArrayRef<SDValue> To, bool AddTo) {
return ((DAGCombiner*)DC)->CombineTo(N, &To[0], To.size(), AddTo);
}
SDValue TargetLowering::DAGCombinerInfo::
CombineTo(SDNode *N, SDValue Res, bool AddTo) {
return ((DAGCombiner*)DC)->CombineTo(N, Res, AddTo);
}
SDValue TargetLowering::DAGCombinerInfo::
CombineTo(SDNode *N, SDValue Res0, SDValue Res1, bool AddTo) {
return ((DAGCombiner*)DC)->CombineTo(N, Res0, Res1, AddTo);
}
bool TargetLowering::DAGCombinerInfo::
recursivelyDeleteUnusedNodes(SDNode *N) {
return ((DAGCombiner*)DC)->recursivelyDeleteUnusedNodes(N);
}
void TargetLowering::DAGCombinerInfo::
CommitTargetLoweringOpt(const TargetLowering::TargetLoweringOpt &TLO) {
return ((DAGCombiner*)DC)->CommitTargetLoweringOpt(TLO);
}
//===----------------------------------------------------------------------===//
// Helper Functions
//===----------------------------------------------------------------------===//
void DAGCombiner::deleteAndRecombine(SDNode *N) {
removeFromWorklist(N);
// If the operands of this node are only used by the node, they will now be
// dead. Make sure to re-visit them and recursively delete dead nodes.
for (const SDValue &Op : N->ops())
// For an operand generating multiple values, one of the values may
// become dead allowing further simplification (e.g. split index
// arithmetic from an indexed load).
if (Op->hasOneUse() || Op->getNumValues() > 1)
AddToWorklist(Op.getNode());
DAG.DeleteNode(N);
}
// APInts must be the same size for most operations, this helper
// function zero extends the shorter of the pair so that they match.
// We provide an Offset so that we can create bitwidths that won't overflow.
static void zeroExtendToMatch(APInt &LHS, APInt &RHS, unsigned Offset = 0) {
unsigned Bits = Offset + std::max(LHS.getBitWidth(), RHS.getBitWidth());
LHS = LHS.zext(Bits);
RHS = RHS.zext(Bits);
}
// Return true if this node is a setcc, or is a select_cc
// that selects between the target values used for true and false, making it
// equivalent to a setcc. Also, set the incoming LHS, RHS, and CC references to
// the appropriate nodes based on the type of node we are checking. This
// simplifies life a bit for the callers.
bool DAGCombiner::isSetCCEquivalent(SDValue N, SDValue &LHS, SDValue &RHS,
SDValue &CC, bool MatchStrict) const {
if (N.getOpcode() == ISD::SETCC) {
LHS = N.getOperand(0);
RHS = N.getOperand(1);
CC = N.getOperand(2);
return true;
}
if (MatchStrict &&
(N.getOpcode() == ISD::STRICT_FSETCC ||
N.getOpcode() == ISD::STRICT_FSETCCS)) {
LHS = N.getOperand(1);
RHS = N.getOperand(2);
CC = N.getOperand(3);
return true;
}
if (N.getOpcode() != ISD::SELECT_CC || !TLI.isConstTrueVal(N.getOperand(2)) ||
!TLI.isConstFalseVal(N.getOperand(3)))
return false;
if (TLI.getBooleanContents(N.getValueType()) ==
TargetLowering::UndefinedBooleanContent)
return false;
LHS = N.getOperand(0);
RHS = N.getOperand(1);
CC = N.getOperand(4);
return true;
}
/// Return true if this is a SetCC-equivalent operation with only one use.
/// If this is true, it allows the users to invert the operation for free when
/// it is profitable to do so.
bool DAGCombiner::isOneUseSetCC(SDValue N) const {
SDValue N0, N1, N2;
if (isSetCCEquivalent(N, N0, N1, N2) && N->hasOneUse())
return true;
return false;
}
static bool isConstantSplatVectorMaskForType(SDNode *N, EVT ScalarTy) {
if (!ScalarTy.isSimple())
return false;
uint64_t MaskForTy = 0ULL;
switch (ScalarTy.getSimpleVT().SimpleTy) {
case MVT::i8:
MaskForTy = 0xFFULL;
break;
case MVT::i16:
MaskForTy = 0xFFFFULL;
break;
case MVT::i32:
MaskForTy = 0xFFFFFFFFULL;
break;
default:
return false;
break;
}
APInt Val;
if (ISD::isConstantSplatVector(N, Val))
return Val.getLimitedValue() == MaskForTy;
return false;
}
// Determines if it is a constant integer or a splat/build vector of constant
// integers (and undefs).
// Do not permit build vector implicit truncation.
static bool isConstantOrConstantVector(SDValue N, bool NoOpaques = false) {
if (ConstantSDNode *Const = dyn_cast<ConstantSDNode>(N))
return !(Const->isOpaque() && NoOpaques);
if (N.getOpcode() != ISD::BUILD_VECTOR && N.getOpcode() != ISD::SPLAT_VECTOR)
return false;
unsigned BitWidth = N.getScalarValueSizeInBits();
for (const SDValue &Op : N->op_values()) {
if (Op.isUndef())
continue;
ConstantSDNode *Const = dyn_cast<ConstantSDNode>(Op);
if (!Const || Const->getAPIntValue().getBitWidth() != BitWidth ||
(Const->isOpaque() && NoOpaques))
return false;
}
return true;
}
// Determines if a BUILD_VECTOR is composed of all-constants possibly mixed with
// undef's.
static bool isAnyConstantBuildVector(SDValue V, bool NoOpaques = false) {
if (V.getOpcode() != ISD::BUILD_VECTOR)
return false;
return isConstantOrConstantVector(V, NoOpaques) ||
ISD::isBuildVectorOfConstantFPSDNodes(V.getNode());
}
// Determine if this an indexed load with an opaque target constant index.
static bool canSplitIdx(LoadSDNode *LD) {
return MaySplitLoadIndex &&
(LD->getOperand(2).getOpcode() != ISD::TargetConstant ||
!cast<ConstantSDNode>(LD->getOperand(2))->isOpaque());
}
bool DAGCombiner::reassociationCanBreakAddressingModePattern(unsigned Opc,
const SDLoc &DL,
SDNode *N,
SDValue N0,
SDValue N1) {
// Currently this only tries to ensure we don't undo the GEP splits done by
// CodeGenPrepare when shouldConsiderGEPOffsetSplit is true. To ensure this,
// we check if the following transformation would be problematic:
// (load/store (add, (add, x, offset1), offset2)) ->
// (load/store (add, x, offset1+offset2)).
if (Opc != ISD::ADD || N0.getOpcode() != ISD::ADD)
return false;
if (N0.hasOneUse())
return false;
auto *C1 = dyn_cast<ConstantSDNode>(N0.getOperand(1));
auto *C2 = dyn_cast<ConstantSDNode>(N1);
if (!C1 || !C2)
return false;
const APInt &C1APIntVal = C1->getAPIntValue();
const APInt &C2APIntVal = C2->getAPIntValue();
if (C1APIntVal.getBitWidth() > 64 || C2APIntVal.getBitWidth() > 64)
return false;
const APInt CombinedValueIntVal = C1APIntVal + C2APIntVal;
if (CombinedValueIntVal.getBitWidth() > 64)
return false;
const int64_t CombinedValue = CombinedValueIntVal.getSExtValue();
for (SDNode *Node : N->uses()) {
auto LoadStore = dyn_cast<MemSDNode>(Node);
if (LoadStore) {
// Is x[offset2] already not a legal addressing mode? If so then
// reassociating the constants breaks nothing (we test offset2 because
// that's the one we hope to fold into the load or store).
TargetLoweringBase::AddrMode AM;
AM.HasBaseReg = true;
AM.BaseOffs = C2APIntVal.getSExtValue();
EVT VT = LoadStore->getMemoryVT();
unsigned AS = LoadStore->getAddressSpace();
Type *AccessTy = VT.getTypeForEVT(*DAG.getContext());
if (!TLI.isLegalAddressingMode(DAG.getDataLayout(), AM, AccessTy, AS))
continue;
// Would x[offset1+offset2] still be a legal addressing mode?
AM.BaseOffs = CombinedValue;
if (!TLI.isLegalAddressingMode(DAG.getDataLayout(), AM, AccessTy, AS))
return true;
}
}
return false;
}
// Helper for DAGCombiner::reassociateOps. Try to reassociate an expression
// such as (Opc N0, N1), if \p N0 is the same kind of operation as \p Opc.
SDValue DAGCombiner::reassociateOpsCommutative(unsigned Opc, const SDLoc &DL,
SDValue N0, SDValue N1) {
EVT VT = N0.getValueType();
if (N0.getOpcode() != Opc)
return SDValue();
SDValue N00 = N0.getOperand(0);
SDValue N01 = N0.getOperand(1);
if (DAG.isConstantIntBuildVectorOrConstantInt(peekThroughBitcasts(N01))) {
if (DAG.isConstantIntBuildVectorOrConstantInt(peekThroughBitcasts(N1))) {
// Reassociate: (op (op x, c1), c2) -> (op x, (op c1, c2))
if (SDValue OpNode = DAG.FoldConstantArithmetic(Opc, DL, VT, {N01, N1}))
return DAG.getNode(Opc, DL, VT, N00, OpNode);
return SDValue();
}
if (TLI.isReassocProfitable(DAG, N0, N1)) {
// Reassociate: (op (op x, c1), y) -> (op (op x, y), c1)
// iff (op x, c1) has one use
SDValue OpNode = DAG.getNode(Opc, SDLoc(N0), VT, N00, N1);
return DAG.getNode(Opc, DL, VT, OpNode, N01);
}
}
// Check for repeated operand logic simplifications.
if (Opc == ISD::AND || Opc == ISD::OR) {
// (N00 & N01) & N00 --> N00 & N01
// (N00 & N01) & N01 --> N00 & N01
// (N00 | N01) | N00 --> N00 | N01
// (N00 | N01) | N01 --> N00 | N01
if (N1 == N00 || N1 == N01)
return N0;
}
if (Opc == ISD::XOR) {
// (N00 ^ N01) ^ N00 --> N01
if (N1 == N00)
return N01;
// (N00 ^ N01) ^ N01 --> N00
if (N1 == N01)
return N00;
}
return SDValue();
}
// Try to reassociate commutative binops.
SDValue DAGCombiner::reassociateOps(unsigned Opc, const SDLoc &DL, SDValue N0,
SDValue N1, SDNodeFlags Flags) {
assert(TLI.isCommutativeBinOp(Opc) && "Operation not commutative.");
// Floating-point reassociation is not allowed without loose FP math.
if (N0.getValueType().isFloatingPoint() ||
N1.getValueType().isFloatingPoint())
if (!Flags.hasAllowReassociation() || !Flags.hasNoSignedZeros())
return SDValue();
if (SDValue Combined = reassociateOpsCommutative(Opc, DL, N0, N1))
return Combined;
if (SDValue Combined = reassociateOpsCommutative(Opc, DL, N1, N0))
return Combined;
return SDValue();
}
SDValue DAGCombiner::CombineTo(SDNode *N, const SDValue *To, unsigned NumTo,
bool AddTo) {
assert(N->getNumValues() == NumTo && "Broken CombineTo call!");
++NodesCombined;
LLVM_DEBUG(dbgs() << "\nReplacing.1 "; N->dump(&DAG); dbgs() << "\nWith: ";
To[0].dump(&DAG);
dbgs() << " and " << NumTo - 1 << " other values\n");
for (unsigned i = 0, e = NumTo; i != e; ++i)
assert((!To[i].getNode() ||
N->getValueType(i) == To[i].getValueType()) &&
"Cannot combine value to value of different type!");
WorklistRemover DeadNodes(*this);
DAG.ReplaceAllUsesWith(N, To);
if (AddTo) {
// Push the new nodes and any users onto the worklist
for (unsigned i = 0, e = NumTo; i != e; ++i) {
if (To[i].getNode())
AddToWorklistWithUsers(To[i].getNode());
}
}
// Finally, if the node is now dead, remove it from the graph. The node
// may not be dead if the replacement process recursively simplified to
// something else needing this node.
if (N->use_empty())
deleteAndRecombine(N);
return SDValue(N, 0);
}
void DAGCombiner::
CommitTargetLoweringOpt(const TargetLowering::TargetLoweringOpt &TLO) {
// Replace the old value with the new one.
++NodesCombined;
LLVM_DEBUG(dbgs() << "\nReplacing.2 "; TLO.Old.dump(&DAG);
dbgs() << "\nWith: "; TLO.New.dump(&DAG); dbgs() << '\n');
// Replace all uses. If any nodes become isomorphic to other nodes and
// are deleted, make sure to remove them from our worklist.
WorklistRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(TLO.Old, TLO.New);
// Push the new node and any (possibly new) users onto the worklist.
AddToWorklistWithUsers(TLO.New.getNode());
// Finally, if the node is now dead, remove it from the graph. The node
// may not be dead if the replacement process recursively simplified to
// something else needing this node.
if (TLO.Old->use_empty())
deleteAndRecombine(TLO.Old.getNode());
}
/// Check the specified integer node value to see if it can be simplified or if
/// things it uses can be simplified by bit propagation. If so, return true.
bool DAGCombiner::SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
const APInt &DemandedElts,
bool AssumeSingleUse) {
TargetLowering::TargetLoweringOpt TLO(DAG, LegalTypes, LegalOperations);
KnownBits Known;
if (!TLI.SimplifyDemandedBits(Op, DemandedBits, DemandedElts, Known, TLO, 0,
AssumeSingleUse))
return false;
// Revisit the node.
AddToWorklist(Op.getNode());
CommitTargetLoweringOpt(TLO);
return true;
}
/// Check the specified vector node value to see if it can be simplified or
/// if things it uses can be simplified as it only uses some of the elements.
/// If so, return true.
bool DAGCombiner::SimplifyDemandedVectorElts(SDValue Op,
const APInt &DemandedElts,
bool AssumeSingleUse) {
TargetLowering::TargetLoweringOpt TLO(DAG, LegalTypes, LegalOperations);
APInt KnownUndef, KnownZero;
if (!TLI.SimplifyDemandedVectorElts(Op, DemandedElts, KnownUndef, KnownZero,
TLO, 0, AssumeSingleUse))
return false;
// Revisit the node.
AddToWorklist(Op.getNode());
CommitTargetLoweringOpt(TLO);
return true;
}
void DAGCombiner::ReplaceLoadWithPromotedLoad(SDNode *Load, SDNode *ExtLoad) {
SDLoc DL(Load);
EVT VT = Load->getValueType(0);
SDValue Trunc = DAG.getNode(ISD::TRUNCATE, DL, VT, SDValue(ExtLoad, 0));
LLVM_DEBUG(dbgs() << "\nReplacing.9 "; Load->dump(&DAG); dbgs() << "\nWith: ";
Trunc.dump(&DAG); dbgs() << '\n');
WorklistRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(SDValue(Load, 0), Trunc);
DAG.ReplaceAllUsesOfValueWith(SDValue(Load, 1), SDValue(ExtLoad, 1));
deleteAndRecombine(Load);
AddToWorklist(Trunc.getNode());
}
SDValue DAGCombiner::PromoteOperand(SDValue Op, EVT PVT, bool &Replace) {
Replace = false;
SDLoc DL(Op);
if (ISD::isUNINDEXEDLoad(Op.getNode())) {
LoadSDNode *LD = cast<LoadSDNode>(Op);
EVT MemVT = LD->getMemoryVT();
ISD::LoadExtType ExtType = ISD::isNON_EXTLoad(LD) ? ISD::EXTLOAD
: LD->getExtensionType();
Replace = true;
return DAG.getExtLoad(ExtType, DL, PVT,
LD->getChain(), LD->getBasePtr(),
MemVT, LD->getMemOperand());
}
unsigned Opc = Op.getOpcode();
switch (Opc) {
default: break;
case ISD::AssertSext:
if (SDValue Op0 = SExtPromoteOperand(Op.getOperand(0), PVT))
return DAG.getNode(ISD::AssertSext, DL, PVT, Op0, Op.getOperand(1));
break;
case ISD::AssertZext:
if (SDValue Op0 = ZExtPromoteOperand(Op.getOperand(0), PVT))
return DAG.getNode(ISD::AssertZext, DL, PVT, Op0, Op.getOperand(1));
break;
case ISD::Constant: {
unsigned ExtOpc =
Op.getValueType().isByteSized() ? ISD::SIGN_EXTEND : ISD::ZERO_EXTEND;
return DAG.getNode(ExtOpc, DL, PVT, Op);
}
}
if (!TLI.isOperationLegal(ISD::ANY_EXTEND, PVT))
return SDValue();
return DAG.getNode(ISD::ANY_EXTEND, DL, PVT, Op);
}
SDValue DAGCombiner::SExtPromoteOperand(SDValue Op, EVT PVT) {
if (!TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG, PVT))
return SDValue();
EVT OldVT = Op.getValueType();
SDLoc DL(Op);
bool Replace = false;
SDValue NewOp = PromoteOperand(Op, PVT, Replace);
if (!NewOp.getNode())
return SDValue();
AddToWorklist(NewOp.getNode());
if (Replace)
ReplaceLoadWithPromotedLoad(Op.getNode(), NewOp.getNode());
return DAG.getNode(ISD::SIGN_EXTEND_INREG, DL, NewOp.getValueType(), NewOp,
DAG.getValueType(OldVT));
}
SDValue DAGCombiner::ZExtPromoteOperand(SDValue Op, EVT PVT) {
EVT OldVT = Op.getValueType();
SDLoc DL(Op);
bool Replace = false;
SDValue NewOp = PromoteOperand(Op, PVT, Replace);
if (!NewOp.getNode())
return SDValue();
AddToWorklist(NewOp.getNode());
if (Replace)
ReplaceLoadWithPromotedLoad(Op.getNode(), NewOp.getNode());
return DAG.getZeroExtendInReg(NewOp, DL, OldVT);
}
/// Promote the specified integer binary operation if the target indicates it is
/// beneficial. e.g. On x86, it's usually better to promote i16 operations to
/// i32 since i16 instructions are longer.
SDValue DAGCombiner::PromoteIntBinOp(SDValue Op) {
if (!LegalOperations)
return SDValue();
EVT VT = Op.getValueType();
if (VT.isVector() || !VT.isInteger())
return SDValue();
// If operation type is 'undesirable', e.g. i16 on x86, consider
// promoting it.
unsigned Opc = Op.getOpcode();
if (TLI.isTypeDesirableForOp(Opc, VT))
return SDValue();
EVT PVT = VT;
// Consult target whether it is a good idea to promote this operation and
// what's the right type to promote it to.
if (TLI.IsDesirableToPromoteOp(Op, PVT)) {
assert(PVT != VT && "Don't know what type to promote to!");
LLVM_DEBUG(dbgs() << "\nPromoting "; Op.dump(&DAG));
bool Replace0 = false;
SDValue N0 = Op.getOperand(0);
SDValue NN0 = PromoteOperand(N0, PVT, Replace0);
bool Replace1 = false;
SDValue N1 = Op.getOperand(1);
SDValue NN1 = PromoteOperand(N1, PVT, Replace1);
SDLoc DL(Op);
SDValue RV =
DAG.getNode(ISD::TRUNCATE, DL, VT, DAG.getNode(Opc, DL, PVT, NN0, NN1));
// We are always replacing N0/N1's use in N and only need additional
// replacements if there are additional uses.
// Note: We are checking uses of the *nodes* (SDNode) rather than values
// (SDValue) here because the node may reference multiple values
// (for example, the chain value of a load node).
Replace0 &= !N0->hasOneUse();
Replace1 &= (N0 != N1) && !N1->hasOneUse();
// Combine Op here so it is preserved past replacements.
CombineTo(Op.getNode(), RV);
// If operands have a use ordering, make sure we deal with
// predecessor first.
if (Replace0 && Replace1 && N0->isPredecessorOf(N1.getNode())) {
std::swap(N0, N1);
std::swap(NN0, NN1);
}
if (Replace0) {
AddToWorklist(NN0.getNode());
ReplaceLoadWithPromotedLoad(N0.getNode(), NN0.getNode());
}
if (Replace1) {
AddToWorklist(NN1.getNode());
ReplaceLoadWithPromotedLoad(N1.getNode(), NN1.getNode());
}
return Op;
}
return SDValue();
}
/// Promote the specified integer shift operation if the target indicates it is
/// beneficial. e.g. On x86, it's usually better to promote i16 operations to
/// i32 since i16 instructions are longer.
SDValue DAGCombiner::PromoteIntShiftOp(SDValue Op) {
if (!LegalOperations)
return SDValue();
EVT VT = Op.getValueType();
if (VT.isVector() || !VT.isInteger())
return SDValue();
// If operation type is 'undesirable', e.g. i16 on x86, consider
// promoting it.
unsigned Opc = Op.getOpcode();
if (TLI.isTypeDesirableForOp(Opc, VT))
return SDValue();
EVT PVT = VT;
// Consult target whether it is a good idea to promote this operation and
// what's the right type to promote it to.
if (TLI.IsDesirableToPromoteOp(Op, PVT)) {
assert(PVT != VT && "Don't know what type to promote to!");
LLVM_DEBUG(dbgs() << "\nPromoting "; Op.dump(&DAG));
bool Replace = false;
SDValue N0 = Op.getOperand(0);
if (Opc == ISD::SRA)
N0 = SExtPromoteOperand(N0, PVT);
else if (Opc == ISD::SRL)
N0 = ZExtPromoteOperand(N0, PVT);
else
N0 = PromoteOperand(N0, PVT, Replace);
if (!N0.getNode())
return SDValue();
SDLoc DL(Op);
SDValue N1 = Op.getOperand(1);
SDValue RV =
DAG.getNode(ISD::TRUNCATE, DL, VT, DAG.getNode(Opc, DL, PVT, N0, N1));
if (Replace)
ReplaceLoadWithPromotedLoad(Op.getOperand(0).getNode(), N0.getNode());
// Deal with Op being deleted.
if (Op && Op.getOpcode() != ISD::DELETED_NODE)
return RV;
}
return SDValue();
}
SDValue DAGCombiner::PromoteExtend(SDValue Op) {
if (!LegalOperations)
return SDValue();
EVT VT = Op.getValueType();
if (VT.isVector() || !VT.isInteger())
return SDValue();
// If operation type is 'undesirable', e.g. i16 on x86, consider
// promoting it.
unsigned Opc = Op.getOpcode();
if (TLI.isTypeDesirableForOp(Opc, VT))
return SDValue();
EVT PVT = VT;
// Consult target whether it is a good idea to promote this operation and
// what's the right type to promote it to.
if (TLI.IsDesirableToPromoteOp(Op, PVT)) {
assert(PVT != VT && "Don't know what type to promote to!");
// fold (aext (aext x)) -> (aext x)
// fold (aext (zext x)) -> (zext x)
// fold (aext (sext x)) -> (sext x)
LLVM_DEBUG(dbgs() << "\nPromoting "; Op.dump(&DAG));
return DAG.getNode(Op.getOpcode(), SDLoc(Op), VT, Op.getOperand(0));
}
return SDValue();
}
bool DAGCombiner::PromoteLoad(SDValue Op) {
if (!LegalOperations)
return false;
if (!ISD::isUNINDEXEDLoad(Op.getNode()))
return false;
EVT VT = Op.getValueType();
if (VT.isVector() || !VT.isInteger())
return false;
// If operation type is 'undesirable', e.g. i16 on x86, consider
// promoting it.
unsigned Opc = Op.getOpcode();
if (TLI.isTypeDesirableForOp(Opc, VT))
return false;
EVT PVT = VT;
// Consult target whether it is a good idea to promote this operation and
// what's the right type to promote it to.
if (TLI.IsDesirableToPromoteOp(Op, PVT)) {
assert(PVT != VT && "Don't know what type to promote to!");
SDLoc DL(Op);
SDNode *N = Op.getNode();
LoadSDNode *LD = cast<LoadSDNode>(N);
EVT MemVT = LD->getMemoryVT();
ISD::LoadExtType ExtType = ISD::isNON_EXTLoad(LD) ? ISD::EXTLOAD
: LD->getExtensionType();
SDValue NewLD = DAG.getExtLoad(ExtType, DL, PVT,
LD->getChain(), LD->getBasePtr(),
MemVT, LD->getMemOperand());
SDValue Result = DAG.getNode(ISD::TRUNCATE, DL, VT, NewLD);
LLVM_DEBUG(dbgs() << "\nPromoting "; N->dump(&DAG); dbgs() << "\nTo: ";
Result.dump(&DAG); dbgs() << '\n');
WorklistRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result);
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), NewLD.getValue(1));
deleteAndRecombine(N);
AddToWorklist(Result.getNode());
return true;
}
return false;
}
/// Recursively delete a node which has no uses and any operands for
/// which it is the only use.
///
/// Note that this both deletes the nodes and removes them from the worklist.
/// It also adds any nodes who have had a user deleted to the worklist as they
/// may now have only one use and subject to other combines.
bool DAGCombiner::recursivelyDeleteUnusedNodes(SDNode *N) {
if (!N->use_empty())
return false;
SmallSetVector<SDNode *, 16> Nodes;
Nodes.insert(N);
do {
N = Nodes.pop_back_val();
if (!N)
continue;
if (N->use_empty()) {
for (const SDValue &ChildN : N->op_values())
Nodes.insert(ChildN.getNode());
removeFromWorklist(N);
DAG.DeleteNode(N);
} else {
AddToWorklist(N);
}
} while (!Nodes.empty());
return true;
}
//===----------------------------------------------------------------------===//
// Main DAG Combiner implementation
//===----------------------------------------------------------------------===//
void DAGCombiner::Run(CombineLevel AtLevel) {
// set the instance variables, so that the various visit routines may use it.
Level = AtLevel;
LegalDAG = Level >= AfterLegalizeDAG;
LegalOperations = Level >= AfterLegalizeVectorOps;
LegalTypes = Level >= AfterLegalizeTypes;
WorklistInserter AddNodes(*this);
// Add all the dag nodes to the worklist.
for (SDNode &Node : DAG.allnodes())
AddToWorklist(&Node);
// Create a dummy node (which is not added to allnodes), that adds a reference
// to the root node, preventing it from being deleted, and tracking any
// changes of the root.
HandleSDNode Dummy(DAG.getRoot());
// While we have a valid worklist entry node, try to combine it.
while (SDNode *N = getNextWorklistEntry()) {
// If N has no uses, it is dead. Make sure to revisit all N's operands once
// N is deleted from the DAG, since they too may now be dead or may have a
// reduced number of uses, allowing other xforms.
if (recursivelyDeleteUnusedNodes(N))
continue;
WorklistRemover DeadNodes(*this);
// If this combine is running after legalizing the DAG, re-legalize any
// nodes pulled off the worklist.
if (LegalDAG) {
SmallSetVector<SDNode *, 16> UpdatedNodes;
bool NIsValid = DAG.LegalizeOp(N, UpdatedNodes);
for (SDNode *LN : UpdatedNodes)
AddToWorklistWithUsers(LN);
if (!NIsValid)
continue;
}
LLVM_DEBUG(dbgs() << "\nCombining: "; N->dump(&DAG));
// Add any operands of the new node which have not yet been combined to the
// worklist as well. Because the worklist uniques things already, this
// won't repeatedly process the same operand.
CombinedNodes.insert(N);
for (const SDValue &ChildN : N->op_values())
if (!CombinedNodes.count(ChildN.getNode()))
AddToWorklist(ChildN.getNode());
SDValue RV = combine(N);
if (!RV.getNode())
continue;
++NodesCombined;
// If we get back the same node we passed in, rather than a new node or
// zero, we know that the node must have defined multiple values and
// CombineTo was used. Since CombineTo takes care of the worklist
// mechanics for us, we have no work to do in this case.
if (RV.getNode() == N)
continue;
assert(N->getOpcode() != ISD::DELETED_NODE &&
RV.getOpcode() != ISD::DELETED_NODE &&
"Node was deleted but visit returned new node!");
LLVM_DEBUG(dbgs() << " ... into: "; RV.dump(&DAG));
if (N->getNumValues() == RV->getNumValues())
DAG.ReplaceAllUsesWith(N, RV.getNode());
else {
assert(N->getValueType(0) == RV.getValueType() &&
N->getNumValues() == 1 && "Type mismatch");
DAG.ReplaceAllUsesWith(N, &RV);
}
// Push the new node and any users onto the worklist. Omit this if the
// new node is the EntryToken (e.g. if a store managed to get optimized
// out), because re-visiting the EntryToken and its users will not uncover
// any additional opportunities, but there may be a large number of such
// users, potentially causing compile time explosion.
if (RV.getOpcode() != ISD::EntryToken) {
AddToWorklist(RV.getNode());
AddUsersToWorklist(RV.getNode());
}
// Finally, if the node is now dead, remove it from the graph. The node
// may not be dead if the replacement process recursively simplified to
// something else needing this node. This will also take care of adding any
// operands which have lost a user to the worklist.
recursivelyDeleteUnusedNodes(N);
}
// If the root changed (e.g. it was a dead load, update the root).
DAG.setRoot(Dummy.getValue());
DAG.RemoveDeadNodes();
}
SDValue DAGCombiner::visit(SDNode *N) {
switch (N->getOpcode()) {
default: break;
case ISD::TokenFactor: return visitTokenFactor(N);
case ISD::MERGE_VALUES: return visitMERGE_VALUES(N);
case ISD::ADD: return visitADD(N);
case ISD::SUB: return visitSUB(N);
case ISD::SADDSAT:
case ISD::UADDSAT: return visitADDSAT(N);
case ISD::SSUBSAT:
case ISD::USUBSAT: return visitSUBSAT(N);
case ISD::ADDC: return visitADDC(N);
case ISD::SADDO:
case ISD::UADDO: return visitADDO(N);
case ISD::SUBC: return visitSUBC(N);
case ISD::SSUBO:
case ISD::USUBO: return visitSUBO(N);
case ISD::ADDE: return visitADDE(N);
case ISD::ADDCARRY: return visitADDCARRY(N);
case ISD::SADDO_CARRY: return visitSADDO_CARRY(N);
case ISD::SUBE: return visitSUBE(N);
case ISD::SUBCARRY: return visitSUBCARRY(N);
case ISD::SSUBO_CARRY: return visitSSUBO_CARRY(N);
case ISD::SMULFIX:
case ISD::SMULFIXSAT:
case ISD::UMULFIX:
case ISD::UMULFIXSAT: return visitMULFIX(N);
case ISD::MUL: return visitMUL(N);
case ISD::SDIV: return visitSDIV(N);
case ISD::UDIV: return visitUDIV(N);
case ISD::SREM:
case ISD::UREM: return visitREM(N);
case ISD::MULHU: return visitMULHU(N);
case ISD::MULHS: return visitMULHS(N);
case ISD::AVGFLOORS:
case ISD::AVGFLOORU:
case ISD::AVGCEILS:
case ISD::AVGCEILU: return visitAVG(N);
case ISD::SMUL_LOHI: return visitSMUL_LOHI(N);
case ISD::UMUL_LOHI: return visitUMUL_LOHI(N);
case ISD::SMULO:
case ISD::UMULO: return visitMULO(N);
case ISD::SMIN:
case ISD::SMAX:
case ISD::UMIN:
case ISD::UMAX: return visitIMINMAX(N);
case ISD::AND: return visitAND(N);
case ISD::OR: return visitOR(N);
case ISD::XOR: return visitXOR(N);
case ISD::SHL: return visitSHL(N);
case ISD::SRA: return visitSRA(N);
case ISD::SRL: return visitSRL(N);
case ISD::ROTR:
case ISD::ROTL: return visitRotate(N);
case ISD::FSHL:
case ISD::FSHR: return visitFunnelShift(N);
case ISD::SSHLSAT:
case ISD::USHLSAT: return visitSHLSAT(N);
case ISD::ABS: return visitABS(N);
case ISD::BSWAP: return visitBSWAP(N);
case ISD::BITREVERSE: return visitBITREVERSE(N);
case ISD::CTLZ: return visitCTLZ(N);
case ISD::CTLZ_ZERO_UNDEF: return visitCTLZ_ZERO_UNDEF(N);
case ISD::CTTZ: return visitCTTZ(N);
case ISD::CTTZ_ZERO_UNDEF: return visitCTTZ_ZERO_UNDEF(N);
case ISD::CTPOP: return visitCTPOP(N);
case ISD::SELECT: return visitSELECT(N);
case ISD::VSELECT: return visitVSELECT(N);
case ISD::SELECT_CC: return visitSELECT_CC(N);
case ISD::SETCC: return visitSETCC(N);
case ISD::SETCCCARRY: return visitSETCCCARRY(N);
case ISD::SIGN_EXTEND: return visitSIGN_EXTEND(N);
case ISD::ZERO_EXTEND: return visitZERO_EXTEND(N);
case ISD::ANY_EXTEND: return visitANY_EXTEND(N);
case ISD::AssertSext:
case ISD::AssertZext: return visitAssertExt(N);
case ISD::AssertAlign: return visitAssertAlign(N);
case ISD::SIGN_EXTEND_INREG: return visitSIGN_EXTEND_INREG(N);
case ISD::SIGN_EXTEND_VECTOR_INREG:
case ISD::ZERO_EXTEND_VECTOR_INREG: return visitEXTEND_VECTOR_INREG(N);
case ISD::TRUNCATE: return visitTRUNCATE(N);
case ISD::BITCAST: return visitBITCAST(N);
case ISD::BUILD_PAIR: return visitBUILD_PAIR(N);
case ISD::FADD: return visitFADD(N);
case ISD::STRICT_FADD: return visitSTRICT_FADD(N);
case ISD::FSUB: return visitFSUB(N);
case ISD::FMUL: return visitFMUL(N);
case ISD::FMA: return visitFMA(N);
case ISD::FDIV: return visitFDIV(N);
case ISD::FREM: return visitFREM(N);
case ISD::FSQRT: return visitFSQRT(N);
case ISD::FCOPYSIGN: return visitFCOPYSIGN(N);
case ISD::FPOW: return visitFPOW(N);
case ISD::SINT_TO_FP: return visitSINT_TO_FP(N);
case ISD::UINT_TO_FP: return visitUINT_TO_FP(N);
case ISD::FP_TO_SINT: return visitFP_TO_SINT(N);
case ISD::FP_TO_UINT: return visitFP_TO_UINT(N);
case ISD::FP_ROUND: return visitFP_ROUND(N);
case ISD::FP_EXTEND: return visitFP_EXTEND(N);
case ISD::FNEG: return visitFNEG(N);
case ISD::FABS: return visitFABS(N);
case ISD::FFLOOR: return visitFFLOOR(N);
case ISD::FMINNUM:
case ISD::FMAXNUM:
case ISD::FMINIMUM:
case ISD::FMAXIMUM: return visitFMinMax(N);
case ISD::FCEIL: return visitFCEIL(N);
case ISD::FTRUNC: return visitFTRUNC(N);
case ISD::BRCOND: return visitBRCOND(N);
case ISD::BR_CC: return visitBR_CC(N);
case ISD::LOAD: return visitLOAD(N);
case ISD::STORE: return visitSTORE(N);
case ISD::INSERT_VECTOR_ELT: return visitINSERT_VECTOR_ELT(N);
case ISD::EXTRACT_VECTOR_ELT: return visitEXTRACT_VECTOR_ELT(N);
case ISD::BUILD_VECTOR: return visitBUILD_VECTOR(N);
case ISD::CONCAT_VECTORS: return visitCONCAT_VECTORS(N);
case ISD::EXTRACT_SUBVECTOR: return visitEXTRACT_SUBVECTOR(N);
case ISD::VECTOR_SHUFFLE: return visitVECTOR_SHUFFLE(N);
case ISD::SCALAR_TO_VECTOR: return visitSCALAR_TO_VECTOR(N);
case ISD::INSERT_SUBVECTOR: return visitINSERT_SUBVECTOR(N);
case ISD::MGATHER: return visitMGATHER(N);
case ISD::MLOAD: return visitMLOAD(N);
case ISD::MSCATTER: return visitMSCATTER(N);
case ISD::MSTORE: return visitMSTORE(N);
case ISD::LIFETIME_END: return visitLIFETIME_END(N);
case ISD::FP_TO_FP16: return visitFP_TO_FP16(N);
case ISD::FP16_TO_FP: return visitFP16_TO_FP(N);
case ISD::FP_TO_BF16: return visitFP_TO_BF16(N);
case ISD::FREEZE: return visitFREEZE(N);
case ISD::VECREDUCE_FADD:
case ISD::VECREDUCE_FMUL:
case ISD::VECREDUCE_ADD:
case ISD::VECREDUCE_MUL:
case ISD::VECREDUCE_AND:
case ISD::VECREDUCE_OR:
case ISD::VECREDUCE_XOR:
case ISD::VECREDUCE_SMAX:
case ISD::VECREDUCE_SMIN:
case ISD::VECREDUCE_UMAX:
case ISD::VECREDUCE_UMIN:
case ISD::VECREDUCE_FMAX:
case ISD::VECREDUCE_FMIN: return visitVECREDUCE(N);
#define BEGIN_REGISTER_VP_SDNODE(SDOPC, ...) case ISD::SDOPC:
#include "llvm/IR/VPIntrinsics.def"
return visitVPOp(N);
}
return SDValue();
}
SDValue DAGCombiner::combine(SDNode *N) {
SDValue RV;
if (!DisableGenericCombines)
RV = visit(N);
// If nothing happened, try a target-specific DAG combine.
if (!RV.getNode()) {
assert(N->getOpcode() != ISD::DELETED_NODE &&
"Node was deleted but visit returned NULL!");
if (N->getOpcode() >= ISD::BUILTIN_OP_END ||
TLI.hasTargetDAGCombine((ISD::NodeType)N->getOpcode())) {
// Expose the DAG combiner to the target combiner impls.
TargetLowering::DAGCombinerInfo
DagCombineInfo(DAG, Level, false, this);
RV = TLI.PerformDAGCombine(N, DagCombineInfo);
}
}
// If nothing happened still, try promoting the operation.
if (!RV.getNode()) {
switch (N->getOpcode()) {
default: break;
case ISD::ADD:
case ISD::SUB:
case ISD::MUL:
case ISD::AND:
case ISD::OR:
case ISD::XOR:
RV = PromoteIntBinOp(SDValue(N, 0));
break;
case ISD::SHL:
case ISD::SRA:
case ISD::SRL:
RV = PromoteIntShiftOp(SDValue(N, 0));
break;
case ISD::SIGN_EXTEND:
case ISD::ZERO_EXTEND:
case ISD::ANY_EXTEND:
RV = PromoteExtend(SDValue(N, 0));
break;
case ISD::LOAD:
if (PromoteLoad(SDValue(N, 0)))
RV = SDValue(N, 0);
break;
}
}
// If N is a commutative binary node, try to eliminate it if the commuted
// version is already present in the DAG.
if (!RV.getNode() && TLI.isCommutativeBinOp(N->getOpcode()) &&
N->getNumValues() == 1) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
// Constant operands are canonicalized to RHS.
if (N0 != N1 && (isa<ConstantSDNode>(N0) || !isa<ConstantSDNode>(N1))) {
SDValue Ops[] = {N1, N0};
SDNode *CSENode = DAG.getNodeIfExists(N->getOpcode(), N->getVTList(), Ops,
N->getFlags());
if (CSENode)
return SDValue(CSENode, 0);
}
}
return RV;
}
/// Given a node, return its input chain if it has one, otherwise return a null
/// sd operand.
static SDValue getInputChainForNode(SDNode *N) {
if (unsigned NumOps = N->getNumOperands()) {
if (N->getOperand(0).getValueType() == MVT::Other)
return N->getOperand(0);
if (N->getOperand(NumOps-1).getValueType() == MVT::Other)
return N->getOperand(NumOps-1);
for (unsigned i = 1; i < NumOps-1; ++i)
if (N->getOperand(i).getValueType() == MVT::Other)
return N->getOperand(i);
}
return SDValue();
}
SDValue DAGCombiner::visitTokenFactor(SDNode *N) {
// If N has two operands, where one has an input chain equal to the other,
// the 'other' chain is redundant.
if (N->getNumOperands() == 2) {
if (getInputChainForNode(N->getOperand(0).getNode()) == N->getOperand(1))
return N->getOperand(0);
if (getInputChainForNode(N->getOperand(1).getNode()) == N->getOperand(0))
return N->getOperand(1);
}
// Don't simplify token factors if optnone.
if (OptLevel == CodeGenOpt::None)
return SDValue();
// Don't simplify the token factor if the node itself has too many operands.
if (N->getNumOperands() > TokenFactorInlineLimit)
return SDValue();
// If the sole user is a token factor, we should make sure we have a
// chance to merge them together. This prevents TF chains from inhibiting
// optimizations.
if (N->hasOneUse() && N->use_begin()->getOpcode() == ISD::TokenFactor)
AddToWorklist(*(N->use_begin()));
SmallVector<SDNode *, 8> TFs; // List of token factors to visit.
SmallVector<SDValue, 8> Ops; // Ops for replacing token factor.
SmallPtrSet<SDNode*, 16> SeenOps;
bool Changed = false; // If we should replace this token factor.
// Start out with this token factor.
TFs.push_back(N);
// Iterate through token factors. The TFs grows when new token factors are
// encountered.
for (unsigned i = 0; i < TFs.size(); ++i) {
// Limit number of nodes to inline, to avoid quadratic compile times.
// We have to add the outstanding Token Factors to Ops, otherwise we might
// drop Ops from the resulting Token Factors.
if (Ops.size() > TokenFactorInlineLimit) {
for (unsigned j = i; j < TFs.size(); j++)
Ops.emplace_back(TFs[j], 0);
// Drop unprocessed Token Factors from TFs, so we do not add them to the
// combiner worklist later.
TFs.resize(i);
break;
}
SDNode *TF = TFs[i];
// Check each of the operands.
for (const SDValue &Op : TF->op_values()) {
switch (Op.getOpcode()) {
case ISD::EntryToken:
// Entry tokens don't need to be added to the list. They are
// redundant.
Changed = true;
break;
case ISD::TokenFactor:
if (Op.hasOneUse() && !is_contained(TFs, Op.getNode())) {
// Queue up for processing.
TFs.push_back(Op.getNode());
Changed = true;
break;
}
LLVM_FALLTHROUGH;
default:
// Only add if it isn't already in the list.
if (SeenOps.insert(Op.getNode()).second)
Ops.push_back(Op);
else
Changed = true;
break;
}
}
}
// Re-visit inlined Token Factors, to clean them up in case they have been
// removed. Skip the first Token Factor, as this is the current node.
for (unsigned i = 1, e = TFs.size(); i < e; i++)
AddToWorklist(TFs[i]);
// Remove Nodes that are chained to another node in the list. Do so
// by walking up chains breath-first stopping when we've seen
// another operand. In general we must climb to the EntryNode, but we can exit
// early if we find all remaining work is associated with just one operand as
// no further pruning is possible.
// List of nodes to search through and original Ops from which they originate.
SmallVector<std::pair<SDNode *, unsigned>, 8> Worklist;
SmallVector<unsigned, 8> OpWorkCount; // Count of work for each Op.
SmallPtrSet<SDNode *, 16> SeenChains;
bool DidPruneOps = false;
unsigned NumLeftToConsider = 0;
for (const SDValue &Op : Ops) {
Worklist.push_back(std::make_pair(Op.getNode(), NumLeftToConsider++));
OpWorkCount.push_back(1);
}
auto AddToWorklist = [&](unsigned CurIdx, SDNode *Op, unsigned OpNumber) {
// If this is an Op, we can remove the op from the list. Remark any
// search associated with it as from the current OpNumber.
if (SeenOps.contains(Op)) {
Changed = true;
DidPruneOps = true;
unsigned OrigOpNumber = 0;
while (OrigOpNumber < Ops.size() && Ops[OrigOpNumber].getNode() != Op)
OrigOpNumber++;
assert((OrigOpNumber != Ops.size()) &&
"expected to find TokenFactor Operand");
// Re-mark worklist from OrigOpNumber to OpNumber
for (unsigned i = CurIdx + 1; i < Worklist.size(); ++i) {
if (Worklist[i].second == OrigOpNumber) {
Worklist[i].second = OpNumber;
}
}
OpWorkCount[OpNumber] += OpWorkCount[OrigOpNumber];
OpWorkCount[OrigOpNumber] = 0;
NumLeftToConsider--;
}
// Add if it's a new chain
if (SeenChains.insert(Op).second) {
OpWorkCount[OpNumber]++;
Worklist.push_back(std::make_pair(Op, OpNumber));
}
};
for (unsigned i = 0; i < Worklist.size() && i < 1024; ++i) {
// We need at least be consider at least 2 Ops to prune.
if (NumLeftToConsider <= 1)
break;
auto CurNode = Worklist[i].first;
auto CurOpNumber = Worklist[i].second;
assert((OpWorkCount[CurOpNumber] > 0) &&
"Node should not appear in worklist");
switch (CurNode->getOpcode()) {
case ISD::EntryToken:
// Hitting EntryToken is the only way for the search to terminate without
// hitting
// another operand's search. Prevent us from marking this operand
// considered.
NumLeftToConsider++;
break;
case ISD::TokenFactor:
for (const SDValue &Op : CurNode->op_values())
AddToWorklist(i, Op.getNode(), CurOpNumber);
break;
case ISD::LIFETIME_START:
case ISD::LIFETIME_END:
case ISD::CopyFromReg:
case ISD::CopyToReg:
AddToWorklist(i, CurNode->getOperand(0).getNode(), CurOpNumber);
break;
default:
if (auto *MemNode = dyn_cast<MemSDNode>(CurNode))
AddToWorklist(i, MemNode->getChain().getNode(), CurOpNumber);
break;
}
OpWorkCount[CurOpNumber]--;
if (OpWorkCount[CurOpNumber] == 0)
NumLeftToConsider--;
}
// If we've changed things around then replace token factor.
if (Changed) {
SDValue Result;
if (Ops.empty()) {
// The entry token is the only possible outcome.
Result = DAG.getEntryNode();
} else {
if (DidPruneOps) {
SmallVector<SDValue, 8> PrunedOps;
//
for (const SDValue &Op : Ops) {
if (SeenChains.count(Op.getNode()) == 0)
PrunedOps.push_back(Op);
}
Result = DAG.getTokenFactor(SDLoc(N), PrunedOps);
} else {
Result = DAG.getTokenFactor(SDLoc(N), Ops);
}
}
return Result;
}
return SDValue();
}
/// MERGE_VALUES can always be eliminated.
SDValue DAGCombiner::visitMERGE_VALUES(SDNode *N) {
WorklistRemover DeadNodes(*this);
// Replacing results may cause a different MERGE_VALUES to suddenly
// be CSE'd with N, and carry its uses with it. Iterate until no
// uses remain, to ensure that the node can be safely deleted.
// First add the users of this node to the work list so that they
// can be tried again once they have new operands.
AddUsersToWorklist(N);
do {
// Do as a single replacement to avoid rewalking use lists.
SmallVector<SDValue, 8> Ops;
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
Ops.push_back(N->getOperand(i));
DAG.ReplaceAllUsesWith(N, Ops.data());
} while (!N->use_empty());
deleteAndRecombine(N);
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
/// If \p N is a ConstantSDNode with isOpaque() == false return it casted to a
/// ConstantSDNode pointer else nullptr.
static ConstantSDNode *getAsNonOpaqueConstant(SDValue N) {
ConstantSDNode *Const = dyn_cast<ConstantSDNode>(N);
return Const != nullptr && !Const->isOpaque() ? Const : nullptr;
}
/// Return true if 'Use' is a load or a store that uses N as its base pointer
/// and that N may be folded in the load / store addressing mode.
static bool canFoldInAddressingMode(SDNode *N, SDNode *Use, SelectionDAG &DAG,
const TargetLowering &TLI) {
EVT VT;
unsigned AS;
if (LoadSDNode *LD = dyn_cast<LoadSDNode>(Use)) {
if (LD->isIndexed() || LD->getBasePtr().getNode() != N)
return false;
VT = LD->getMemoryVT();
AS = LD->getAddressSpace();
} else if (StoreSDNode *ST = dyn_cast<StoreSDNode>(Use)) {
if (ST->isIndexed() || ST->getBasePtr().getNode() != N)
return false;
VT = ST->getMemoryVT();
AS = ST->getAddressSpace();
} else if (MaskedLoadSDNode *LD = dyn_cast<MaskedLoadSDNode>(Use)) {
if (LD->isIndexed() || LD->getBasePtr().getNode() != N)
return false;
VT = LD->getMemoryVT();
AS = LD->getAddressSpace();
} else if (MaskedStoreSDNode *ST = dyn_cast<MaskedStoreSDNode>(Use)) {
if (ST->isIndexed() || ST->getBasePtr().getNode() != N)
return false;
VT = ST->getMemoryVT();
AS = ST->getAddressSpace();
} else {
return false;
}
TargetLowering::AddrMode AM;
if (N->getOpcode() == ISD::ADD) {
AM.HasBaseReg = true;
ConstantSDNode *Offset = dyn_cast<ConstantSDNode>(N->getOperand(1));
if (Offset)
// [reg +/- imm]
AM.BaseOffs = Offset->getSExtValue();
else
// [reg +/- reg]
AM.Scale = 1;
} else if (N->getOpcode() == ISD::SUB) {
AM.HasBaseReg = true;
ConstantSDNode *Offset = dyn_cast<ConstantSDNode>(N->getOperand(1));
if (Offset)
// [reg +/- imm]
AM.BaseOffs = -Offset->getSExtValue();
else
// [reg +/- reg]
AM.Scale = 1;
} else {
return false;
}
return TLI.isLegalAddressingMode(DAG.getDataLayout(), AM,
VT.getTypeForEVT(*DAG.getContext()), AS);
}
/// This inverts a canonicalization in IR that replaces a variable select arm
/// with an identity constant. Codegen improves if we re-use the variable
/// operand rather than load a constant. This can also be converted into a
/// masked vector operation if the target supports it.
static SDValue foldSelectWithIdentityConstant(SDNode *N, SelectionDAG &DAG,
bool ShouldCommuteOperands) {
// Match a select as operand 1. The identity constant that we are looking for
// is only valid as operand 1 of a non-commutative binop.
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
if (ShouldCommuteOperands)
std::swap(N0, N1);
// TODO: Should this apply to scalar select too?
if (!N1.hasOneUse() || N1.getOpcode() != ISD::VSELECT)
return SDValue();
unsigned Opcode = N->getOpcode();
EVT VT = N->getValueType(0);
SDValue Cond = N1.getOperand(0);
SDValue TVal = N1.getOperand(1);
SDValue FVal = N1.getOperand(2);
// TODO: The cases should match with IR's ConstantExpr::getBinOpIdentity().
// TODO: Target-specific opcodes could be added. Ex: "isCommutativeBinOp()".
// TODO: With fast-math (NSZ), allow the opposite-sign form of zero?
auto isIdentityConstantForOpcode = [](unsigned Opcode, SDValue V) {
if (ConstantFPSDNode *C = isConstOrConstSplatFP(V)) {
switch (Opcode) {
case ISD::FADD: // X + -0.0 --> X
return C->isZero() && C->isNegative();
case ISD::FSUB: // X - 0.0 --> X
return C->isZero() && !C->isNegative();
case ISD::FMUL: // X * 1.0 --> X
case ISD::FDIV: // X / 1.0 --> X
return C->isExactlyValue(1.0);
}
}
if (ConstantSDNode *C = isConstOrConstSplat(V)) {
switch (Opcode) {
case ISD::ADD: // X + 0 --> X
case ISD::SUB: // X - 0 --> X
case ISD::SHL: // X << 0 --> X
case ISD::SRA: // X s>> 0 --> X
case ISD::SRL: // X u>> 0 --> X
return C->isZero();
case ISD::MUL: // X * 1 --> X
return C->isOne();
}
}
return false;
};
// This transform increases uses of N0, so freeze it to be safe.
// binop N0, (vselect Cond, IDC, FVal) --> vselect Cond, N0, (binop N0, FVal)
if (isIdentityConstantForOpcode(Opcode, TVal)) {
SDValue F0 = DAG.getFreeze(N0);
SDValue NewBO = DAG.getNode(Opcode, SDLoc(N), VT, F0, FVal, N->getFlags());
return DAG.getSelect(SDLoc(N), VT, Cond, F0, NewBO);
}
// binop N0, (vselect Cond, TVal, IDC) --> vselect Cond, (binop N0, TVal), N0
if (isIdentityConstantForOpcode(Opcode, FVal)) {
SDValue F0 = DAG.getFreeze(N0);
SDValue NewBO = DAG.getNode(Opcode, SDLoc(N), VT, F0, TVal, N->getFlags());
return DAG.getSelect(SDLoc(N), VT, Cond, NewBO, F0);
}
return SDValue();
}
SDValue DAGCombiner::foldBinOpIntoSelect(SDNode *BO) {
assert(TLI.isBinOp(BO->getOpcode()) && BO->getNumValues() == 1 &&
"Unexpected binary operator");
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
auto BinOpcode = BO->getOpcode();
EVT VT = BO->getValueType(0);
if (TLI.shouldFoldSelectWithIdentityConstant(BinOpcode, VT)) {
if (SDValue Sel = foldSelectWithIdentityConstant(BO, DAG, false))
return Sel;
if (TLI.isCommutativeBinOp(BO->getOpcode()))
if (SDValue Sel = foldSelectWithIdentityConstant(BO, DAG, true))
return Sel;
}
// Don't do this unless the old select is going away. We want to eliminate the
// binary operator, not replace a binop with a select.
// TODO: Handle ISD::SELECT_CC.
unsigned SelOpNo = 0;
SDValue Sel = BO->getOperand(0);
if (Sel.getOpcode() != ISD::SELECT || !Sel.hasOneUse()) {
SelOpNo = 1;
Sel = BO->getOperand(1);
}
if (Sel.getOpcode() != ISD::SELECT || !Sel.hasOneUse())
return SDValue();
SDValue CT = Sel.getOperand(1);
if (!isConstantOrConstantVector(CT, true) &&
!DAG.isConstantFPBuildVectorOrConstantFP(CT))
return SDValue();
SDValue CF = Sel.getOperand(2);
if (!isConstantOrConstantVector(CF, true) &&
!DAG.isConstantFPBuildVectorOrConstantFP(CF))
return SDValue();
// Bail out if any constants are opaque because we can't constant fold those.
// The exception is "and" and "or" with either 0 or -1 in which case we can
// propagate non constant operands into select. I.e.:
// and (select Cond, 0, -1), X --> select Cond, 0, X
// or X, (select Cond, -1, 0) --> select Cond, -1, X
bool CanFoldNonConst =
(BinOpcode == ISD::AND || BinOpcode == ISD::OR) &&
(isNullOrNullSplat(CT) || isAllOnesOrAllOnesSplat(CT)) &&
(isNullOrNullSplat(CF) || isAllOnesOrAllOnesSplat(CF));
SDValue CBO = BO->getOperand(SelOpNo ^ 1);
if (!CanFoldNonConst &&
!isConstantOrConstantVector(CBO, true) &&
!DAG.isConstantFPBuildVectorOrConstantFP(CBO))
return SDValue();
// We have a select-of-constants followed by a binary operator with a
// constant. Eliminate the binop by pulling the constant math into the select.
// Example: add (select Cond, CT, CF), CBO --> select Cond, CT + CBO, CF + CBO
SDLoc DL(Sel);
SDValue NewCT = SelOpNo ? DAG.getNode(BinOpcode, DL, VT, CBO, CT)
: DAG.getNode(BinOpcode, DL, VT, CT, CBO);
if (!CanFoldNonConst && !NewCT.isUndef() &&
!isConstantOrConstantVector(NewCT, true) &&
!DAG.isConstantFPBuildVectorOrConstantFP(NewCT))
return SDValue();
SDValue NewCF = SelOpNo ? DAG.getNode(BinOpcode, DL, VT, CBO, CF)
: DAG.getNode(BinOpcode, DL, VT, CF, CBO);
if (!CanFoldNonConst && !NewCF.isUndef() &&
!isConstantOrConstantVector(NewCF, true) &&
!DAG.isConstantFPBuildVectorOrConstantFP(NewCF))
return SDValue();
SDValue SelectOp = DAG.getSelect(DL, VT, Sel.getOperand(0), NewCT, NewCF);
SelectOp->setFlags(BO->getFlags());
return SelectOp;
}
static SDValue foldAddSubBoolOfMaskedVal(SDNode *N, SelectionDAG &DAG) {
assert((N->getOpcode() == ISD::ADD || N->getOpcode() == ISD::SUB) &&
"Expecting add or sub");
// Match a constant operand and a zext operand for the math instruction:
// add Z, C
// sub C, Z
bool IsAdd = N->getOpcode() == ISD::ADD;
SDValue C = IsAdd ? N->getOperand(1) : N->getOperand(0);
SDValue Z = IsAdd ? N->getOperand(0) : N->getOperand(1);
auto *CN = dyn_cast<ConstantSDNode>(C);
if (!CN || Z.getOpcode() != ISD::ZERO_EXTEND)
return SDValue();
// Match the zext operand as a setcc of a boolean.
if (Z.getOperand(0).getOpcode() != ISD::SETCC ||
Z.getOperand(0).getValueType() != MVT::i1)
return SDValue();
// Match the compare as: setcc (X & 1), 0, eq.
SDValue SetCC = Z.getOperand(0);
ISD::CondCode CC = cast<CondCodeSDNode>(SetCC->getOperand(2))->get();
if (CC != ISD::SETEQ || !isNullConstant(SetCC.getOperand(1)) ||
SetCC.getOperand(0).getOpcode() != ISD::AND ||
!isOneConstant(SetCC.getOperand(0).getOperand(1)))
return SDValue();
// We are adding/subtracting a constant and an inverted low bit. Turn that
// into a subtract/add of the low bit with incremented/decremented constant:
// add (zext i1 (seteq (X & 1), 0)), C --> sub C+1, (zext (X & 1))
// sub C, (zext i1 (seteq (X & 1), 0)) --> add C-1, (zext (X & 1))
EVT VT = C.getValueType();
SDLoc DL(N);
SDValue LowBit = DAG.getZExtOrTrunc(SetCC.getOperand(0), DL, VT);
SDValue C1 = IsAdd ? DAG.getConstant(CN->getAPIntValue() + 1, DL, VT) :
DAG.getConstant(CN->getAPIntValue() - 1, DL, VT);
return DAG.getNode(IsAdd ? ISD::SUB : ISD::ADD, DL, VT, C1, LowBit);
}
/// Try to fold a 'not' shifted sign-bit with add/sub with constant operand into
/// a shift and add with a different constant.
static SDValue foldAddSubOfSignBit(SDNode *N, SelectionDAG &DAG) {
assert((N->getOpcode() == ISD::ADD || N->getOpcode() == ISD::SUB) &&
"Expecting add or sub");
// We need a constant operand for the add/sub, and the other operand is a
// logical shift right: add (srl), C or sub C, (srl).
bool IsAdd = N->getOpcode() == ISD::ADD;
SDValue ConstantOp = IsAdd ? N->getOperand(1) : N->getOperand(0);
SDValue ShiftOp = IsAdd ? N->getOperand(0) : N->getOperand(1);
if (!DAG.isConstantIntBuildVectorOrConstantInt(ConstantOp) ||
ShiftOp.getOpcode() != ISD::SRL)
return SDValue();
// The shift must be of a 'not' value.
SDValue Not = ShiftOp.getOperand(0);
if (!Not.hasOneUse() || !isBitwiseNot(Not))
return SDValue();
// The shift must be moving the sign bit to the least-significant-bit.
EVT VT = ShiftOp.getValueType();
SDValue ShAmt = ShiftOp.getOperand(1);
ConstantSDNode *ShAmtC = isConstOrConstSplat(ShAmt);
if (!ShAmtC || ShAmtC->getAPIntValue() != (VT.getScalarSizeInBits() - 1))
return SDValue();
// Eliminate the 'not' by adjusting the shift and add/sub constant:
// add (srl (not X), 31), C --> add (sra X, 31), (C + 1)
// sub C, (srl (not X), 31) --> add (srl X, 31), (C - 1)
SDLoc DL(N);
auto ShOpcode = IsAdd ? ISD::SRA : ISD::SRL;
SDValue NewShift = DAG.getNode(ShOpcode, DL, VT, Not.getOperand(0), ShAmt);
if (SDValue NewC =
DAG.FoldConstantArithmetic(IsAdd ? ISD::ADD : ISD::SUB, DL, VT,
{ConstantOp, DAG.getConstant(1, DL, VT)}))
return DAG.getNode(ISD::ADD, DL, VT, NewShift, NewC);
return SDValue();
}
static bool isADDLike(SDValue V, const SelectionDAG &DAG) {
unsigned Opcode = V.getOpcode();
if (Opcode == ISD::OR)
return DAG.haveNoCommonBitsSet(V.getOperand(0), V.getOperand(1));
if (Opcode == ISD::XOR)
return isMinSignedConstant(V.getOperand(1));
return false;
}
/// Try to fold a node that behaves like an ADD (note that N isn't necessarily
/// an ISD::ADD here, it could for example be an ISD::OR if we know that there
/// are no common bits set in the operands).
SDValue DAGCombiner::visitADDLike(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
SDLoc DL(N);
// fold (add x, undef) -> undef
if (N0.isUndef())
return N0;
if (N1.isUndef())
return N1;
// fold (add c1, c2) -> c1+c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::ADD, DL, VT, {N0, N1}))
return C;
// canonicalize constant to RHS
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(ISD::ADD, DL, VT, N1, N0);
// fold vector ops
if (VT.isVector()) {
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
// fold (add x, 0) -> x, vector edition
if (ISD::isConstantSplatVectorAllZeros(N1.getNode()))
return N0;
}
// fold (add x, 0) -> x
if (isNullConstant(N1))
return N0;
if (N0.getOpcode() == ISD::SUB) {
SDValue N00 = N0.getOperand(0);
SDValue N01 = N0.getOperand(1);
// fold ((A-c1)+c2) -> (A+(c2-c1))
if (SDValue Sub = DAG.FoldConstantArithmetic(ISD::SUB, DL, VT, {N1, N01}))
return DAG.getNode(ISD::ADD, DL, VT, N0.getOperand(0), Sub);
// fold ((c1-A)+c2) -> (c1+c2)-A
if (SDValue Add = DAG.FoldConstantArithmetic(ISD::ADD, DL, VT, {N1, N00}))
return DAG.getNode(ISD::SUB, DL, VT, Add, N0.getOperand(1));
}
// add (sext i1 X), 1 -> zext (not i1 X)
// We don't transform this pattern:
// add (zext i1 X), -1 -> sext (not i1 X)
// because most (?) targets generate better code for the zext form.
if (N0.getOpcode() == ISD::SIGN_EXTEND && N0.hasOneUse() &&
isOneOrOneSplat(N1)) {
SDValue X = N0.getOperand(0);
if ((!LegalOperations ||
(TLI.isOperationLegal(ISD::XOR, X.getValueType()) &&
TLI.isOperationLegal(ISD::ZERO_EXTEND, VT))) &&
X.getScalarValueSizeInBits() == 1) {
SDValue Not = DAG.getNOT(DL, X, X.getValueType());
return DAG.getNode(ISD::ZERO_EXTEND, DL, VT, Not);
}
}
// Fold (add (or x, c0), c1) -> (add x, (c0 + c1))
// iff (or x, c0) is equivalent to (add x, c0).
// Fold (add (xor x, c0), c1) -> (add x, (c0 + c1))
// iff (xor x, c0) is equivalent to (add x, c0).
if (isADDLike(N0, DAG)) {
SDValue N01 = N0.getOperand(1);
if (SDValue Add = DAG.FoldConstantArithmetic(ISD::ADD, DL, VT, {N1, N01}))
return DAG.getNode(ISD::ADD, DL, VT, N0.getOperand(0), Add);
}
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
// reassociate add
if (!reassociationCanBreakAddressingModePattern(ISD::ADD, DL, N, N0, N1)) {
if (SDValue RADD = reassociateOps(ISD::ADD, DL, N0, N1, N->getFlags()))
return RADD;
// Reassociate (add (or x, c), y) -> (add add(x, y), c)) if (or x, c) is
// equivalent to (add x, c).
// Reassociate (add (xor x, c), y) -> (add add(x, y), c)) if (xor x, c) is
// equivalent to (add x, c).
auto ReassociateAddOr = [&](SDValue N0, SDValue N1) {
if (isADDLike(N0, DAG) && N0.hasOneUse() &&
isConstantOrConstantVector(N0.getOperand(1), /* NoOpaque */ true)) {
return DAG.getNode(ISD::ADD, DL, VT,
DAG.getNode(ISD::ADD, DL, VT, N1, N0.getOperand(0)),
N0.getOperand(1));
}
return SDValue();
};
if (SDValue Add = ReassociateAddOr(N0, N1))
return Add;
if (SDValue Add = ReassociateAddOr(N1, N0))
return Add;
}
// fold ((0-A) + B) -> B-A
if (N0.getOpcode() == ISD::SUB && isNullOrNullSplat(N0.getOperand(0)))
return DAG.getNode(ISD::SUB, DL, VT, N1, N0.getOperand(1));
// fold (A + (0-B)) -> A-B
if (N1.getOpcode() == ISD::SUB && isNullOrNullSplat(N1.getOperand(0)))
return DAG.getNode(ISD::SUB, DL, VT, N0, N1.getOperand(1));
// fold (A+(B-A)) -> B
if (N1.getOpcode() == ISD::SUB && N0 == N1.getOperand(1))
return N1.getOperand(0);
// fold ((B-A)+A) -> B
if (N0.getOpcode() == ISD::SUB && N1 == N0.getOperand(1))
return N0.getOperand(0);
// fold ((A-B)+(C-A)) -> (C-B)
if (N0.getOpcode() == ISD::SUB && N1.getOpcode() == ISD::SUB &&
N0.getOperand(0) == N1.getOperand(1))
return DAG.getNode(ISD::SUB, DL, VT, N1.getOperand(0),
N0.getOperand(1));
// fold ((A-B)+(B-C)) -> (A-C)
if (N0.getOpcode() == ISD::SUB && N1.getOpcode() == ISD::SUB &&
N0.getOperand(1) == N1.getOperand(0))
return DAG.getNode(ISD::SUB, DL, VT, N0.getOperand(0),
N1.getOperand(1));
// fold (A+(B-(A+C))) to (B-C)
if (N1.getOpcode() == ISD::SUB && N1.getOperand(1).getOpcode() == ISD::ADD &&
N0 == N1.getOperand(1).getOperand(0))
return DAG.getNode(ISD::SUB, DL, VT, N1.getOperand(0),
N1.getOperand(1).getOperand(1));
// fold (A+(B-(C+A))) to (B-C)
if (N1.getOpcode() == ISD::SUB && N1.getOperand(1).getOpcode() == ISD::ADD &&
N0 == N1.getOperand(1).getOperand(1))
return DAG.getNode(ISD::SUB, DL, VT, N1.getOperand(0),
N1.getOperand(1).getOperand(0));
// fold (A+((B-A)+or-C)) to (B+or-C)
if ((N1.getOpcode() == ISD::SUB || N1.getOpcode() == ISD::ADD) &&
N1.getOperand(0).getOpcode() == ISD::SUB &&
N0 == N1.getOperand(0).getOperand(1))
return DAG.getNode(N1.getOpcode(), DL, VT, N1.getOperand(0).getOperand(0),
N1.getOperand(1));
// fold (A-B)+(C-D) to (A+C)-(B+D) when A or C is constant
if (N0.getOpcode() == ISD::SUB && N1.getOpcode() == ISD::SUB &&
N0->hasOneUse() && N1->hasOneUse()) {
SDValue N00 = N0.getOperand(0);
SDValue N01 = N0.getOperand(1);
SDValue N10 = N1.getOperand(0);
SDValue N11 = N1.getOperand(1);
if (isConstantOrConstantVector(N00) || isConstantOrConstantVector(N10))
return DAG.getNode(ISD::SUB, DL, VT,
DAG.getNode(ISD::ADD, SDLoc(N0), VT, N00, N10),
DAG.getNode(ISD::ADD, SDLoc(N1), VT, N01, N11));
}
// fold (add (umax X, C), -C) --> (usubsat X, C)
if (N0.getOpcode() == ISD::UMAX && hasOperation(ISD::USUBSAT, VT)) {
auto MatchUSUBSAT = [](ConstantSDNode *Max, ConstantSDNode *Op) {
return (!Max && !Op) ||
(Max && Op && Max->getAPIntValue() == (-Op->getAPIntValue()));
};
if (ISD::matchBinaryPredicate(N0.getOperand(1), N1, MatchUSUBSAT,
/*AllowUndefs*/ true))
return DAG.getNode(ISD::USUBSAT, DL, VT, N0.getOperand(0),
N0.getOperand(1));
}
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
if (isOneOrOneSplat(N1)) {
// fold (add (xor a, -1), 1) -> (sub 0, a)
if (isBitwiseNot(N0))
return DAG.getNode(ISD::SUB, DL, VT, DAG.getConstant(0, DL, VT),
N0.getOperand(0));
// fold (add (add (xor a, -1), b), 1) -> (sub b, a)
if (N0.getOpcode() == ISD::ADD) {
SDValue A, Xor;
if (isBitwiseNot(N0.getOperand(0))) {
A = N0.getOperand(1);
Xor = N0.getOperand(0);
} else if (isBitwiseNot(N0.getOperand(1))) {
A = N0.getOperand(0);
Xor = N0.getOperand(1);
}
if (Xor)
return DAG.getNode(ISD::SUB, DL, VT, A, Xor.getOperand(0));
}
// Look for:
// add (add x, y), 1
// And if the target does not like this form then turn into:
// sub y, (xor x, -1)
if (!TLI.preferIncOfAddToSubOfNot(VT) && N0.getOpcode() == ISD::ADD &&
N0.hasOneUse()) {
SDValue Not = DAG.getNode(ISD::XOR, DL, VT, N0.getOperand(0),
DAG.getAllOnesConstant(DL, VT));
return DAG.getNode(ISD::SUB, DL, VT, N0.getOperand(1), Not);
}
}
// (x - y) + -1 -> add (xor y, -1), x
if (N0.getOpcode() == ISD::SUB && N0.hasOneUse() &&
isAllOnesOrAllOnesSplat(N1)) {
SDValue Xor = DAG.getNode(ISD::XOR, DL, VT, N0.getOperand(1), N1);
return DAG.getNode(ISD::ADD, DL, VT, Xor, N0.getOperand(0));
}
if (SDValue Combined = visitADDLikeCommutative(N0, N1, N))
return Combined;
if (SDValue Combined = visitADDLikeCommutative(N1, N0, N))
return Combined;
return SDValue();
}
SDValue DAGCombiner::visitADD(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
SDLoc DL(N);
if (SDValue Combined = visitADDLike(N))
return Combined;
if (SDValue V = foldAddSubBoolOfMaskedVal(N, DAG))
return V;
if (SDValue V = foldAddSubOfSignBit(N, DAG))
return V;
// fold (a+b) -> (a|b) iff a and b share no bits.
if ((!LegalOperations || TLI.isOperationLegal(ISD::OR, VT)) &&
DAG.haveNoCommonBitsSet(N0, N1))
return DAG.getNode(ISD::OR, DL, VT, N0, N1);
// Fold (add (vscale * C0), (vscale * C1)) to (vscale * (C0 + C1)).
if (N0.getOpcode() == ISD::VSCALE && N1.getOpcode() == ISD::VSCALE) {
const APInt &C0 = N0->getConstantOperandAPInt(0);
const APInt &C1 = N1->getConstantOperandAPInt(0);
return DAG.getVScale(DL, VT, C0 + C1);
}
// fold a+vscale(c1)+vscale(c2) -> a+vscale(c1+c2)
if ((N0.getOpcode() == ISD::ADD) &&
(N0.getOperand(1).getOpcode() == ISD::VSCALE) &&
(N1.getOpcode() == ISD::VSCALE)) {
const APInt &VS0 = N0.getOperand(1)->getConstantOperandAPInt(0);
const APInt &VS1 = N1->getConstantOperandAPInt(0);
SDValue VS = DAG.getVScale(DL, VT, VS0 + VS1);
return DAG.getNode(ISD::ADD, DL, VT, N0.getOperand(0), VS);
}
// Fold (add step_vector(c1), step_vector(c2) to step_vector(c1+c2))
if (N0.getOpcode() == ISD::STEP_VECTOR &&
N1.getOpcode() == ISD::STEP_VECTOR) {
const APInt &C0 = N0->getConstantOperandAPInt(0);
const APInt &C1 = N1->getConstantOperandAPInt(0);
APInt NewStep = C0 + C1;
return DAG.getStepVector(DL, VT, NewStep);
}
// Fold a + step_vector(c1) + step_vector(c2) to a + step_vector(c1+c2)
if ((N0.getOpcode() == ISD::ADD) &&
(N0.getOperand(1).getOpcode() == ISD::STEP_VECTOR) &&
(N1.getOpcode() == ISD::STEP_VECTOR)) {
const APInt &SV0 = N0.getOperand(1)->getConstantOperandAPInt(0);
const APInt &SV1 = N1->getConstantOperandAPInt(0);
APInt NewStep = SV0 + SV1;
SDValue SV = DAG.getStepVector(DL, VT, NewStep);
return DAG.getNode(ISD::ADD, DL, VT, N0.getOperand(0), SV);
}
return SDValue();
}
SDValue DAGCombiner::visitADDSAT(SDNode *N) {
unsigned Opcode = N->getOpcode();
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
SDLoc DL(N);
// fold (add_sat x, undef) -> -1
if (N0.isUndef() || N1.isUndef())
return DAG.getAllOnesConstant(DL, VT);
// fold (add_sat c1, c2) -> c3
if (SDValue C = DAG.FoldConstantArithmetic(Opcode, DL, VT, {N0, N1}))
return C;
// canonicalize constant to RHS
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(Opcode, DL, VT, N1, N0);
// fold vector ops
if (VT.isVector()) {
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
// fold (add_sat x, 0) -> x, vector edition
if (ISD::isConstantSplatVectorAllZeros(N1.getNode()))
return N0;
}
// fold (add_sat x, 0) -> x
if (isNullConstant(N1))
return N0;
// If it cannot overflow, transform into an add.
if (Opcode == ISD::UADDSAT)
if (DAG.computeOverflowKind(N0, N1) == SelectionDAG::OFK_Never)
return DAG.getNode(ISD::ADD, DL, VT, N0, N1);
return SDValue();
}
static SDValue getAsCarry(const TargetLowering &TLI, SDValue V) {
bool Masked = false;
// First, peel away TRUNCATE/ZERO_EXTEND/AND nodes due to legalization.
while (true) {
if (V.getOpcode() == ISD::TRUNCATE || V.getOpcode() == ISD::ZERO_EXTEND) {
V = V.getOperand(0);
continue;
}
if (V.getOpcode() == ISD::AND && isOneConstant(V.getOperand(1))) {
Masked = true;
V = V.getOperand(0);
continue;
}
break;
}
// If this is not a carry, return.
if (V.getResNo() != 1)
return SDValue();
if (V.getOpcode() != ISD::ADDCARRY && V.getOpcode() != ISD::SUBCARRY &&
V.getOpcode() != ISD::UADDO && V.getOpcode() != ISD::USUBO)
return SDValue();
EVT VT = V->getValueType(0);
if (!TLI.isOperationLegalOrCustom(V.getOpcode(), VT))
return SDValue();
// If the result is masked, then no matter what kind of bool it is we can
// return. If it isn't, then we need to make sure the bool type is either 0 or
// 1 and not other values.
if (Masked ||
TLI.getBooleanContents(V.getValueType()) ==
TargetLoweringBase::ZeroOrOneBooleanContent)
return V;
return SDValue();
}
/// Given the operands of an add/sub operation, see if the 2nd operand is a
/// masked 0/1 whose source operand is actually known to be 0/-1. If so, invert
/// the opcode and bypass the mask operation.
static SDValue foldAddSubMasked1(bool IsAdd, SDValue N0, SDValue N1,
SelectionDAG &DAG, const SDLoc &DL) {
if (N1.getOpcode() != ISD::AND || !isOneOrOneSplat(N1->getOperand(1)))
return SDValue();
EVT VT = N0.getValueType();
if (DAG.ComputeNumSignBits(N1.getOperand(0)) != VT.getScalarSizeInBits())
return SDValue();
// add N0, (and (AssertSext X, i1), 1) --> sub N0, X
// sub N0, (and (AssertSext X, i1), 1) --> add N0, X
return DAG.getNode(IsAdd ? ISD::SUB : ISD::ADD, DL, VT, N0, N1.getOperand(0));
}
/// Helper for doing combines based on N0 and N1 being added to each other.
SDValue DAGCombiner::visitADDLikeCommutative(SDValue N0, SDValue N1,
SDNode *LocReference) {
EVT VT = N0.getValueType();
SDLoc DL(LocReference);
// fold (add x, shl(0 - y, n)) -> sub(x, shl(y, n))
if (N1.getOpcode() == ISD::SHL && N1.getOperand(0).getOpcode() == ISD::SUB &&
isNullOrNullSplat(N1.getOperand(0).getOperand(0)))
return DAG.getNode(ISD::SUB, DL, VT, N0,
DAG.getNode(ISD::SHL, DL, VT,
N1.getOperand(0).getOperand(1),
N1.getOperand(1)));
if (SDValue V = foldAddSubMasked1(true, N0, N1, DAG, DL))
return V;
// Look for:
// add (add x, 1), y
// And if the target does not like this form then turn into:
// sub y, (xor x, -1)
if (!TLI.preferIncOfAddToSubOfNot(VT) && N0.getOpcode() == ISD::ADD &&
N0.hasOneUse() && isOneOrOneSplat(N0.getOperand(1))) {
SDValue Not = DAG.getNode(ISD::XOR, DL, VT, N0.getOperand(0),
DAG.getAllOnesConstant(DL, VT));
return DAG.getNode(ISD::SUB, DL, VT, N1, Not);
}
if (N0.getOpcode() == ISD::SUB && N0.hasOneUse()) {
// Hoist one-use subtraction by non-opaque constant:
// (x - C) + y -> (x + y) - C
// This is necessary because SUB(X,C) -> ADD(X,-C) doesn't work for vectors.
if (isConstantOrConstantVector(N0.getOperand(1), /*NoOpaques=*/true)) {
SDValue Add = DAG.getNode(ISD::ADD, DL, VT, N0.getOperand(0), N1);
return DAG.getNode(ISD::SUB, DL, VT, Add, N0.getOperand(1));
}
// Hoist one-use subtraction from non-opaque constant:
// (C - x) + y -> (y - x) + C
if (isConstantOrConstantVector(N0.getOperand(0), /*NoOpaques=*/true)) {
SDValue Sub = DAG.getNode(ISD::SUB, DL, VT, N1, N0.getOperand(1));
return DAG.getNode(ISD::ADD, DL, VT, Sub, N0.getOperand(0));
}
}
// If the target's bool is represented as 0/1, prefer to make this 'sub 0/1'
// rather than 'add 0/-1' (the zext should get folded).
// add (sext i1 Y), X --> sub X, (zext i1 Y)
if (N0.getOpcode() == ISD::SIGN_EXTEND &&
N0.getOperand(0).getScalarValueSizeInBits() == 1 &&
TLI.getBooleanContents(VT) == TargetLowering::ZeroOrOneBooleanContent) {
SDValue ZExt = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, N0.getOperand(0));
return DAG.getNode(ISD::SUB, DL, VT, N1, ZExt);
}
// add X, (sextinreg Y i1) -> sub X, (and Y 1)
if (N1.getOpcode() == ISD::SIGN_EXTEND_INREG) {
VTSDNode *TN = cast<VTSDNode>(N1.getOperand(1));
if (TN->getVT() == MVT::i1) {
SDValue ZExt = DAG.getNode(ISD::AND, DL, VT, N1.getOperand(0),
DAG.getConstant(1, DL, VT));
return DAG.getNode(ISD::SUB, DL, VT, N0, ZExt);
}
}
// (add X, (addcarry Y, 0, Carry)) -> (addcarry X, Y, Carry)
if (N1.getOpcode() == ISD::ADDCARRY && isNullConstant(N1.getOperand(1)) &&
N1.getResNo() == 0)
return DAG.getNode(ISD::ADDCARRY, DL, N1->getVTList(),
N0, N1.getOperand(0), N1.getOperand(2));
// (add X, Carry) -> (addcarry X, 0, Carry)
if (TLI.isOperationLegalOrCustom(ISD::ADDCARRY, VT))
if (SDValue Carry = getAsCarry(TLI, N1))
return DAG.getNode(ISD::ADDCARRY, DL,
DAG.getVTList(VT, Carry.getValueType()), N0,
DAG.getConstant(0, DL, VT), Carry);
return SDValue();
}
SDValue DAGCombiner::visitADDC(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
SDLoc DL(N);
// If the flag result is dead, turn this into an ADD.
if (!N->hasAnyUseOfValue(1))
return CombineTo(N, DAG.getNode(ISD::ADD, DL, VT, N0, N1),
DAG.getNode(ISD::CARRY_FALSE, DL, MVT::Glue));
// canonicalize constant to RHS.
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
if (N0C && !N1C)
return DAG.getNode(ISD::ADDC, DL, N->getVTList(), N1, N0);
// fold (addc x, 0) -> x + no carry out
if (isNullConstant(N1))
return CombineTo(N, N0, DAG.getNode(ISD::CARRY_FALSE,
DL, MVT::Glue));
// If it cannot overflow, transform into an add.
if (DAG.computeOverflowKind(N0, N1) == SelectionDAG::OFK_Never)
return CombineTo(N, DAG.getNode(ISD::ADD, DL, VT, N0, N1),
DAG.getNode(ISD::CARRY_FALSE, DL, MVT::Glue));
return SDValue();
}
/**
* Flips a boolean if it is cheaper to compute. If the Force parameters is set,
* then the flip also occurs if computing the inverse is the same cost.
* This function returns an empty SDValue in case it cannot flip the boolean
* without increasing the cost of the computation. If you want to flip a boolean
* no matter what, use DAG.getLogicalNOT.
*/
static SDValue extractBooleanFlip(SDValue V, SelectionDAG &DAG,
const TargetLowering &TLI,
bool Force) {
if (Force && isa<ConstantSDNode>(V))
return DAG.getLogicalNOT(SDLoc(V), V, V.getValueType());
if (V.getOpcode() != ISD::XOR)
return SDValue();
ConstantSDNode *Const = isConstOrConstSplat(V.getOperand(1), false);
if (!Const)
return SDValue();
EVT VT = V.getValueType();
bool IsFlip = false;
switch(TLI.getBooleanContents(VT)) {
case TargetLowering::ZeroOrOneBooleanContent:
IsFlip = Const->isOne();
break;
case TargetLowering::ZeroOrNegativeOneBooleanContent:
IsFlip = Const->isAllOnes();
break;
case TargetLowering::UndefinedBooleanContent:
IsFlip = (Const->getAPIntValue() & 0x01) == 1;
break;
}
if (IsFlip)
return V.getOperand(0);
if (Force)
return DAG.getLogicalNOT(SDLoc(V), V, V.getValueType());
return SDValue();
}
SDValue DAGCombiner::visitADDO(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
bool IsSigned = (ISD::SADDO == N->getOpcode());
EVT CarryVT = N->getValueType(1);
SDLoc DL(N);
// If the flag result is dead, turn this into an ADD.
if (!N->hasAnyUseOfValue(1))
return CombineTo(N, DAG.getNode(ISD::ADD, DL, VT, N0, N1),
DAG.getUNDEF(CarryVT));
// canonicalize constant to RHS.
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(N->getOpcode(), DL, N->getVTList(), N1, N0);
// fold (addo x, 0) -> x + no carry out
if (isNullOrNullSplat(N1))
return CombineTo(N, N0, DAG.getConstant(0, DL, CarryVT));
if (!IsSigned) {
// If it cannot overflow, transform into an add.
if (DAG.computeOverflowKind(N0, N1) == SelectionDAG::OFK_Never)
return CombineTo(N, DAG.getNode(ISD::ADD, DL, VT, N0, N1),
DAG.getConstant(0, DL, CarryVT));
// fold (uaddo (xor a, -1), 1) -> (usub 0, a) and flip carry.
if (isBitwiseNot(N0) && isOneOrOneSplat(N1)) {
SDValue Sub = DAG.getNode(ISD::USUBO, DL, N->getVTList(),
DAG.getConstant(0, DL, VT), N0.getOperand(0));
return CombineTo(
N, Sub, DAG.getLogicalNOT(DL, Sub.getValue(1), Sub->getValueType(1)));
}
if (SDValue Combined = visitUADDOLike(N0, N1, N))
return Combined;
if (SDValue Combined = visitUADDOLike(N1, N0, N))
return Combined;
}
return SDValue();
}
SDValue DAGCombiner::visitUADDOLike(SDValue N0, SDValue N1, SDNode *N) {
EVT VT = N0.getValueType();
if (VT.isVector())
return SDValue();
// (uaddo X, (addcarry Y, 0, Carry)) -> (addcarry X, Y, Carry)
// If Y + 1 cannot overflow.
if (N1.getOpcode() == ISD::ADDCARRY && isNullConstant(N1.getOperand(1))) {
SDValue Y = N1.getOperand(0);
SDValue One = DAG.getConstant(1, SDLoc(N), Y.getValueType());
if (DAG.computeOverflowKind(Y, One) == SelectionDAG::OFK_Never)
return DAG.getNode(ISD::ADDCARRY, SDLoc(N), N->getVTList(), N0, Y,
N1.getOperand(2));
}
// (uaddo X, Carry) -> (addcarry X, 0, Carry)
if (TLI.isOperationLegalOrCustom(ISD::ADDCARRY, VT))
if (SDValue Carry = getAsCarry(TLI, N1))
return DAG.getNode(ISD::ADDCARRY, SDLoc(N), N->getVTList(), N0,
DAG.getConstant(0, SDLoc(N), VT), Carry);
return SDValue();
}
SDValue DAGCombiner::visitADDE(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue CarryIn = N->getOperand(2);
// canonicalize constant to RHS
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
if (N0C && !N1C)
return DAG.getNode(ISD::ADDE, SDLoc(N), N->getVTList(),
N1, N0, CarryIn);
// fold (adde x, y, false) -> (addc x, y)
if (CarryIn.getOpcode() == ISD::CARRY_FALSE)
return DAG.getNode(ISD::ADDC, SDLoc(N), N->getVTList(), N0, N1);
return SDValue();
}
SDValue DAGCombiner::visitADDCARRY(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue CarryIn = N->getOperand(2);
SDLoc DL(N);
// canonicalize constant to RHS
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
if (N0C && !N1C)
return DAG.getNode(ISD::ADDCARRY, DL, N->getVTList(), N1, N0, CarryIn);
// fold (addcarry x, y, false) -> (uaddo x, y)
if (isNullConstant(CarryIn)) {
if (!LegalOperations ||
TLI.isOperationLegalOrCustom(ISD::UADDO, N->getValueType(0)))
return DAG.getNode(ISD::UADDO, DL, N->getVTList(), N0, N1);
}
// fold (addcarry 0, 0, X) -> (and (ext/trunc X), 1) and no carry.
if (isNullConstant(N0) && isNullConstant(N1)) {
EVT VT = N0.getValueType();
EVT CarryVT = CarryIn.getValueType();
SDValue CarryExt = DAG.getBoolExtOrTrunc(CarryIn, DL, VT, CarryVT);
AddToWorklist(CarryExt.getNode());
return CombineTo(N, DAG.getNode(ISD::AND, DL, VT, CarryExt,
DAG.getConstant(1, DL, VT)),
DAG.getConstant(0, DL, CarryVT));
}
if (SDValue Combined = visitADDCARRYLike(N0, N1, CarryIn, N))
return Combined;
if (SDValue Combined = visitADDCARRYLike(N1, N0, CarryIn, N))
return Combined;
return SDValue();
}
SDValue DAGCombiner::visitSADDO_CARRY(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue CarryIn = N->getOperand(2);
SDLoc DL(N);
// canonicalize constant to RHS
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
if (N0C && !N1C)
return DAG.getNode(ISD::SADDO_CARRY, DL, N->getVTList(), N1, N0, CarryIn);
// fold (saddo_carry x, y, false) -> (saddo x, y)
if (isNullConstant(CarryIn)) {
if (!LegalOperations ||
TLI.isOperationLegalOrCustom(ISD::SADDO, N->getValueType(0)))
return DAG.getNode(ISD::SADDO, DL, N->getVTList(), N0, N1);
}
return SDValue();
}
/**
* If we are facing some sort of diamond carry propapagtion pattern try to
* break it up to generate something like:
* (addcarry X, 0, (addcarry A, B, Z):Carry)
*
* The end result is usually an increase in operation required, but because the
* carry is now linearized, other tranforms can kick in and optimize the DAG.
*
* Patterns typically look something like
* (uaddo A, B)
* / \
* Carry Sum
* | \
* | (addcarry *, 0, Z)
* | /
* \ Carry
* | /
* (addcarry X, *, *)
*
* But numerous variation exist. Our goal is to identify A, B, X and Z and
* produce a combine with a single path for carry propagation.
*/
static SDValue combineADDCARRYDiamond(DAGCombiner &Combiner, SelectionDAG &DAG,
SDValue X, SDValue Carry0, SDValue Carry1,
SDNode *N) {
if (Carry1.getResNo() != 1 || Carry0.getResNo() != 1)
return SDValue();
if (Carry1.getOpcode() != ISD::UADDO)
return SDValue();
SDValue Z;
/**
* First look for a suitable Z. It will present itself in the form of
* (addcarry Y, 0, Z) or its equivalent (uaddo Y, 1) for Z=true
*/
if (Carry0.getOpcode() == ISD::ADDCARRY &&
isNullConstant(Carry0.getOperand(1))) {
Z = Carry0.getOperand(2);
} else if (Carry0.getOpcode() == ISD::UADDO &&
isOneConstant(Carry0.getOperand(1))) {
EVT VT = Combiner.getSetCCResultType(Carry0.getValueType());
Z = DAG.getConstant(1, SDLoc(Carry0.getOperand(1)), VT);
} else {
// We couldn't find a suitable Z.
return SDValue();
}
auto cancelDiamond = [&](SDValue A,SDValue B) {
SDLoc DL(N);
SDValue NewY = DAG.getNode(ISD::ADDCARRY, DL, Carry0->getVTList(), A, B, Z);
Combiner.AddToWorklist(NewY.getNode());
return DAG.getNode(ISD::ADDCARRY, DL, N->getVTList(), X,
DAG.getConstant(0, DL, X.getValueType()),
NewY.getValue(1));
};
/**
* (uaddo A, B)
* |
* Sum
* |
* (addcarry *, 0, Z)
*/
if (Carry0.getOperand(0) == Carry1.getValue(0)) {
return cancelDiamond(Carry1.getOperand(0), Carry1.getOperand(1));
}
/**
* (addcarry A, 0, Z)
* |
* Sum
* |
* (uaddo *, B)
*/
if (Carry1.getOperand(0) == Carry0.getValue(0)) {
return cancelDiamond(Carry0.getOperand(0), Carry1.getOperand(1));
}
if (Carry1.getOperand(1) == Carry0.getValue(0)) {
return cancelDiamond(Carry1.getOperand(0), Carry0.getOperand(0));
}
return SDValue();
}
// If we are facing some sort of diamond carry/borrow in/out pattern try to
// match patterns like:
//
// (uaddo A, B) CarryIn
// | \ |
// | \ |
// PartialSum PartialCarryOutX /
// | | /
// | ____|____________/
// | / |
// (uaddo *, *) \________
// | \ \
// | \ |
// | PartialCarryOutY |
// | \ |
// | \ /
// AddCarrySum | ______/
// | /
// CarryOut = (or *, *)
//
// And generate ADDCARRY (or SUBCARRY) with two result values:
//
// {AddCarrySum, CarryOut} = (addcarry A, B, CarryIn)
//
// Our goal is to identify A, B, and CarryIn and produce ADDCARRY/SUBCARRY with
// a single path for carry/borrow out propagation:
static SDValue combineCarryDiamond(SelectionDAG &DAG, const TargetLowering &TLI,
SDValue N0, SDValue N1, SDNode *N) {
SDValue Carry0 = getAsCarry(TLI, N0);
if (!Carry0)
return SDValue();
SDValue Carry1 = getAsCarry(TLI, N1);
if (!Carry1)
return SDValue();
unsigned Opcode = Carry0.getOpcode();
if (Opcode != Carry1.getOpcode())
return SDValue();
if (Opcode != ISD::UADDO && Opcode != ISD::USUBO)
return SDValue();
// Canonicalize the add/sub of A and B (the top node in the above ASCII art)
// as Carry0 and the add/sub of the carry in as Carry1 (the middle node).
if (Carry1.getNode()->isOperandOf(Carry0.getNode()))
std::swap(Carry0, Carry1);
// Check if nodes are connected in expected way.
if (Carry1.getOperand(0) != Carry0.getValue(0) &&
Carry1.getOperand(1) != Carry0.getValue(0))
return SDValue();
// The carry in value must be on the righthand side for subtraction.
unsigned CarryInOperandNum =
Carry1.getOperand(0) == Carry0.getValue(0) ? 1 : 0;
if (Opcode == ISD::USUBO && CarryInOperandNum != 1)
return SDValue();
SDValue CarryIn = Carry1.getOperand(CarryInOperandNum);
unsigned NewOp = Opcode == ISD::UADDO ? ISD::ADDCARRY : ISD::SUBCARRY;
if (!TLI.isOperationLegalOrCustom(NewOp, Carry0.getValue(0).getValueType()))
return SDValue();
// Verify that the carry/borrow in is plausibly a carry/borrow bit.
// TODO: make getAsCarry() aware of how partial carries are merged.
if (CarryIn.getOpcode() != ISD::ZERO_EXTEND)
return SDValue();
CarryIn = CarryIn.getOperand(0);
if (CarryIn.getValueType() != MVT::i1)
return SDValue();
SDLoc DL(N);
SDValue Merged =
DAG.getNode(NewOp, DL, Carry1->getVTList(), Carry0.getOperand(0),
Carry0.getOperand(1), CarryIn);
// Please note that because we have proven that the result of the UADDO/USUBO
// of A and B feeds into the UADDO/USUBO that does the carry/borrow in, we can
// therefore prove that if the first UADDO/USUBO overflows, the second
// UADDO/USUBO cannot. For example consider 8-bit numbers where 0xFF is the
// maximum value.
//
// 0xFF + 0xFF == 0xFE with carry but 0xFE + 1 does not carry
// 0x00 - 0xFF == 1 with a carry/borrow but 1 - 1 == 0 (no carry/borrow)
//
// This is important because it means that OR and XOR can be used to merge
// carry flags; and that AND can return a constant zero.
//
// TODO: match other operations that can merge flags (ADD, etc)
DAG.ReplaceAllUsesOfValueWith(Carry1.getValue(0), Merged.getValue(0));
if (N->getOpcode() == ISD::AND)
return DAG.getConstant(0, DL, MVT::i1);
return Merged.getValue(1);
}
SDValue DAGCombiner::visitADDCARRYLike(SDValue N0, SDValue N1, SDValue CarryIn,
SDNode *N) {
// fold (addcarry (xor a, -1), b, c) -> (subcarry b, a, !c) and flip carry.
if (isBitwiseNot(N0))
if (SDValue NotC = extractBooleanFlip(CarryIn, DAG, TLI, true)) {
SDLoc DL(N);
SDValue Sub = DAG.getNode(ISD::SUBCARRY, DL, N->getVTList(), N1,
N0.getOperand(0), NotC);
return CombineTo(
N, Sub, DAG.getLogicalNOT(DL, Sub.getValue(1), Sub->getValueType(1)));
}
// Iff the flag result is dead:
// (addcarry (add|uaddo X, Y), 0, Carry) -> (addcarry X, Y, Carry)
// Don't do this if the Carry comes from the uaddo. It won't remove the uaddo
// or the dependency between the instructions.
if ((N0.getOpcode() == ISD::ADD ||
(N0.getOpcode() == ISD::UADDO && N0.getResNo() == 0 &&
N0.getValue(1) != CarryIn)) &&
isNullConstant(N1) && !N->hasAnyUseOfValue(1))
return DAG.getNode(ISD::ADDCARRY, SDLoc(N), N->getVTList(),
N0.getOperand(0), N0.getOperand(1), CarryIn);
/**
* When one of the addcarry argument is itself a carry, we may be facing
* a diamond carry propagation. In which case we try to transform the DAG
* to ensure linear carry propagation if that is possible.
*/
if (auto Y = getAsCarry(TLI, N1)) {
// Because both are carries, Y and Z can be swapped.
if (auto R = combineADDCARRYDiamond(*this, DAG, N0, Y, CarryIn, N))
return R;
if (auto R = combineADDCARRYDiamond(*this, DAG, N0, CarryIn, Y, N))
return R;
}
return SDValue();
}
// Attempt to create a USUBSAT(LHS, RHS) node with DstVT, performing a
// clamp/truncation if necessary.
static SDValue getTruncatedUSUBSAT(EVT DstVT, EVT SrcVT, SDValue LHS,
SDValue RHS, SelectionDAG &DAG,
const SDLoc &DL) {
assert(DstVT.getScalarSizeInBits() <= SrcVT.getScalarSizeInBits() &&
"Illegal truncation");
if (DstVT == SrcVT)
return DAG.getNode(ISD::USUBSAT, DL, DstVT, LHS, RHS);
// If the LHS is zero-extended then we can perform the USUBSAT as DstVT by
// clamping RHS.
APInt UpperBits = APInt::getBitsSetFrom(SrcVT.getScalarSizeInBits(),
DstVT.getScalarSizeInBits());
if (!DAG.MaskedValueIsZero(LHS, UpperBits))
return SDValue();
SDValue SatLimit =
DAG.getConstant(APInt::getLowBitsSet(SrcVT.getScalarSizeInBits(),
DstVT.getScalarSizeInBits()),
DL, SrcVT);
RHS = DAG.getNode(ISD::UMIN, DL, SrcVT, RHS, SatLimit);
RHS = DAG.getNode(ISD::TRUNCATE, DL, DstVT, RHS);
LHS = DAG.getNode(ISD::TRUNCATE, DL, DstVT, LHS);
return DAG.getNode(ISD::USUBSAT, DL, DstVT, LHS, RHS);
}
// Try to find umax(a,b) - b or a - umin(a,b) patterns that may be converted to
// usubsat(a,b), optionally as a truncated type.
SDValue DAGCombiner::foldSubToUSubSat(EVT DstVT, SDNode *N) {
if (N->getOpcode() != ISD::SUB ||
!(!LegalOperations || hasOperation(ISD::USUBSAT, DstVT)))
return SDValue();
EVT SubVT = N->getValueType(0);
SDValue Op0 = N->getOperand(0);
SDValue Op1 = N->getOperand(1);
// Try to find umax(a,b) - b or a - umin(a,b) patterns
// they may be converted to usubsat(a,b).
if (Op0.getOpcode() == ISD::UMAX && Op0.hasOneUse()) {
SDValue MaxLHS = Op0.getOperand(0);
SDValue MaxRHS = Op0.getOperand(1);
if (MaxLHS == Op1)
return getTruncatedUSUBSAT(DstVT, SubVT, MaxRHS, Op1, DAG, SDLoc(N));
if (MaxRHS == Op1)
return getTruncatedUSUBSAT(DstVT, SubVT, MaxLHS, Op1, DAG, SDLoc(N));
}
if (Op1.getOpcode() == ISD::UMIN && Op1.hasOneUse()) {
SDValue MinLHS = Op1.getOperand(0);
SDValue MinRHS = Op1.getOperand(1);
if (MinLHS == Op0)
return getTruncatedUSUBSAT(DstVT, SubVT, Op0, MinRHS, DAG, SDLoc(N));
if (MinRHS == Op0)
return getTruncatedUSUBSAT(DstVT, SubVT, Op0, MinLHS, DAG, SDLoc(N));
}
// sub(a,trunc(umin(zext(a),b))) -> usubsat(a,trunc(umin(b,SatLimit)))
if (Op1.getOpcode() == ISD::TRUNCATE &&
Op1.getOperand(0).getOpcode() == ISD::UMIN &&
Op1.getOperand(0).hasOneUse()) {
SDValue MinLHS = Op1.getOperand(0).getOperand(0);
SDValue MinRHS = Op1.getOperand(0).getOperand(1);
if (MinLHS.getOpcode() == ISD::ZERO_EXTEND && MinLHS.getOperand(0) == Op0)
return getTruncatedUSUBSAT(DstVT, MinLHS.getValueType(), MinLHS, MinRHS,
DAG, SDLoc(N));
if (MinRHS.getOpcode() == ISD::ZERO_EXTEND && MinRHS.getOperand(0) == Op0)
return getTruncatedUSUBSAT(DstVT, MinLHS.getValueType(), MinRHS, MinLHS,
DAG, SDLoc(N));
}
return SDValue();
}
// Since it may not be valid to emit a fold to zero for vector initializers
// check if we can before folding.
static SDValue tryFoldToZero(const SDLoc &DL, const TargetLowering &TLI, EVT VT,
SelectionDAG &DAG, bool LegalOperations) {
if (!VT.isVector())
return DAG.getConstant(0, DL, VT);
if (!LegalOperations || TLI.isOperationLegal(ISD::BUILD_VECTOR, VT))
return DAG.getConstant(0, DL, VT);
return SDValue();
}
SDValue DAGCombiner::visitSUB(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
SDLoc DL(N);
auto PeekThroughFreeze = [](SDValue N) {
if (N->getOpcode() == ISD::FREEZE && N.hasOneUse())
return N->getOperand(0);
return N;
};
// fold (sub x, x) -> 0
// FIXME: Refactor this and xor and other similar operations together.
if (PeekThroughFreeze(N0) == PeekThroughFreeze(N1))
return tryFoldToZero(DL, TLI, VT, DAG, LegalOperations);
// fold (sub c1, c2) -> c3
if (SDValue C = DAG.FoldConstantArithmetic(ISD::SUB, DL, VT, {N0, N1}))
return C;
// fold vector ops
if (VT.isVector()) {
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
// fold (sub x, 0) -> x, vector edition
if (ISD::isConstantSplatVectorAllZeros(N1.getNode()))
return N0;
}
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
ConstantSDNode *N1C = getAsNonOpaqueConstant(N1);
// fold (sub x, c) -> (add x, -c)
if (N1C) {
return DAG.getNode(ISD::ADD, DL, VT, N0,
DAG.getConstant(-N1C->getAPIntValue(), DL, VT));
}
if (isNullOrNullSplat(N0)) {
unsigned BitWidth = VT.getScalarSizeInBits();
// Right-shifting everything out but the sign bit followed by negation is
// the same as flipping arithmetic/logical shift type without the negation:
// -(X >>u 31) -> (X >>s 31)
// -(X >>s 31) -> (X >>u 31)
if (N1->getOpcode() == ISD::SRA || N1->getOpcode() == ISD::SRL) {
ConstantSDNode *ShiftAmt = isConstOrConstSplat(N1.getOperand(1));
if (ShiftAmt && ShiftAmt->getAPIntValue() == (BitWidth - 1)) {
auto NewSh = N1->getOpcode() == ISD::SRA ? ISD::SRL : ISD::SRA;
if (!LegalOperations || TLI.isOperationLegal(NewSh, VT))
return DAG.getNode(NewSh, DL, VT, N1.getOperand(0), N1.getOperand(1));
}
}
// 0 - X --> 0 if the sub is NUW.
if (N->getFlags().hasNoUnsignedWrap())
return N0;
if (DAG.MaskedValueIsZero(N1, ~APInt::getSignMask(BitWidth))) {
// N1 is either 0 or the minimum signed value. If the sub is NSW, then
// N1 must be 0 because negating the minimum signed value is undefined.
if (N->getFlags().hasNoSignedWrap())
return N0;
// 0 - X --> X if X is 0 or the minimum signed value.
return N1;
}
// Convert 0 - abs(x).
if (N1.getOpcode() == ISD::ABS && N1.hasOneUse() &&
!TLI.isOperationLegalOrCustom(ISD::ABS, VT))
if (SDValue Result = TLI.expandABS(N1.getNode(), DAG, true))
return Result;
// Fold neg(splat(neg(x)) -> splat(x)
if (VT.isVector()) {
SDValue N1S = DAG.getSplatValue(N1, true);
if (N1S && N1S.getOpcode() == ISD::SUB &&
isNullConstant(N1S.getOperand(0))) {
if (VT.isScalableVector())
return DAG.getSplatVector(VT, DL, N1S.getOperand(1));
return DAG.getSplatBuildVector(VT, DL, N1S.getOperand(1));
}
}
}
// Canonicalize (sub -1, x) -> ~x, i.e. (xor x, -1)
if (isAllOnesOrAllOnesSplat(N0))
return DAG.getNode(ISD::XOR, DL, VT, N1, N0);
// fold (A - (0-B)) -> A+B
if (N1.getOpcode() == ISD::SUB && isNullOrNullSplat(N1.getOperand(0)))
return DAG.getNode(ISD::ADD, DL, VT, N0, N1.getOperand(1));
// fold A-(A-B) -> B
if (N1.getOpcode() == ISD::SUB && N0 == N1.getOperand(0))
return N1.getOperand(1);
// fold (A+B)-A -> B
if (N0.getOpcode() == ISD::ADD && N0.getOperand(0) == N1)
return N0.getOperand(1);
// fold (A+B)-B -> A
if (N0.getOpcode() == ISD::ADD && N0.getOperand(1) == N1)
return N0.getOperand(0);
// fold (A+C1)-C2 -> A+(C1-C2)
if (N0.getOpcode() == ISD::ADD) {
SDValue N01 = N0.getOperand(1);
if (SDValue NewC = DAG.FoldConstantArithmetic(ISD::SUB, DL, VT, {N01, N1}))
return DAG.getNode(ISD::ADD, DL, VT, N0.getOperand(0), NewC);
}
// fold C2-(A+C1) -> (C2-C1)-A
if (N1.getOpcode() == ISD::ADD) {
SDValue N11 = N1.getOperand(1);
if (SDValue NewC = DAG.FoldConstantArithmetic(ISD::SUB, DL, VT, {N0, N11}))
return DAG.getNode(ISD::SUB, DL, VT, NewC, N1.getOperand(0));
}
// fold (A-C1)-C2 -> A-(C1+C2)
if (N0.getOpcode() == ISD::SUB) {
SDValue N01 = N0.getOperand(1);
if (SDValue NewC = DAG.FoldConstantArithmetic(ISD::ADD, DL, VT, {N01, N1}))
return DAG.getNode(ISD::SUB, DL, VT, N0.getOperand(0), NewC);
}
// fold (c1-A)-c2 -> (c1-c2)-A
if (N0.getOpcode() == ISD::SUB) {
SDValue N00 = N0.getOperand(0);
if (SDValue NewC = DAG.FoldConstantArithmetic(ISD::SUB, DL, VT, {N00, N1}))
return DAG.getNode(ISD::SUB, DL, VT, NewC, N0.getOperand(1));
}
// fold ((A+(B+or-C))-B) -> A+or-C
if (N0.getOpcode() == ISD::ADD &&
(N0.getOperand(1).getOpcode() == ISD::SUB ||
N0.getOperand(1).getOpcode() == ISD::ADD) &&
N0.getOperand(1).getOperand(0) == N1)
return DAG.getNode(N0.getOperand(1).getOpcode(), DL, VT, N0.getOperand(0),
N0.getOperand(1).getOperand(1));
// fold ((A+(C+B))-B) -> A+C
if (N0.getOpcode() == ISD::ADD && N0.getOperand(1).getOpcode() == ISD::ADD &&
N0.getOperand(1).getOperand(1) == N1)
return DAG.getNode(ISD::ADD, DL, VT, N0.getOperand(0),
N0.getOperand(1).getOperand(0));
// fold ((A-(B-C))-C) -> A-B
if (N0.getOpcode() == ISD::SUB && N0.getOperand(1).getOpcode() == ISD::SUB &&
N0.getOperand(1).getOperand(1) == N1)
return DAG.getNode(ISD::SUB, DL, VT, N0.getOperand(0),
N0.getOperand(1).getOperand(0));
// fold (A-(B-C)) -> A+(C-B)
if (N1.getOpcode() == ISD::SUB && N1.hasOneUse())
return DAG.getNode(ISD::ADD, DL, VT, N0,
DAG.getNode(ISD::SUB, DL, VT, N1.getOperand(1),
N1.getOperand(0)));
// A - (A & B) -> A & (~B)
if (N1.getOpcode() == ISD::AND) {
SDValue A = N1.getOperand(0);
SDValue B = N1.getOperand(1);
if (A != N0)
std::swap(A, B);
if (A == N0 &&
(N1.hasOneUse() || isConstantOrConstantVector(B, /*NoOpaques=*/true))) {
SDValue InvB =
DAG.getNode(ISD::XOR, DL, VT, B, DAG.getAllOnesConstant(DL, VT));
return DAG.getNode(ISD::AND, DL, VT, A, InvB);
}
}
// fold (X - (-Y * Z)) -> (X + (Y * Z))
if (N1.getOpcode() == ISD::MUL && N1.hasOneUse()) {
if (N1.getOperand(0).getOpcode() == ISD::SUB &&
isNullOrNullSplat(N1.getOperand(0).getOperand(0))) {
SDValue Mul = DAG.getNode(ISD::MUL, DL, VT,
N1.getOperand(0).getOperand(1),
N1.getOperand(1));
return DAG.getNode(ISD::ADD, DL, VT, N0, Mul);
}
if (N1.getOperand(1).getOpcode() == ISD::SUB &&
isNullOrNullSplat(N1.getOperand(1).getOperand(0))) {
SDValue Mul = DAG.getNode(ISD::MUL, DL, VT,
N1.getOperand(0),
N1.getOperand(1).getOperand(1));
return DAG.getNode(ISD::ADD, DL, VT, N0, Mul);
}
}
// If either operand of a sub is undef, the result is undef
if (N0.isUndef())
return N0;
if (N1.isUndef())
return N1;
if (SDValue V = foldAddSubBoolOfMaskedVal(N, DAG))
return V;
if (SDValue V = foldAddSubOfSignBit(N, DAG))
return V;
if (SDValue V = foldAddSubMasked1(false, N0, N1, DAG, SDLoc(N)))
return V;
if (SDValue V = foldSubToUSubSat(VT, N))
return V;
// (x - y) - 1 -> add (xor y, -1), x
if (N0.hasOneUse() && N0.getOpcode() == ISD::SUB && isOneOrOneSplat(N1)) {
SDValue Xor = DAG.getNode(ISD::XOR, DL, VT, N0.getOperand(1),
DAG.getAllOnesConstant(DL, VT));
return DAG.getNode(ISD::ADD, DL, VT, Xor, N0.getOperand(0));
}
// Look for:
// sub y, (xor x, -1)
// And if the target does not like this form then turn into:
// add (add x, y), 1
if (TLI.preferIncOfAddToSubOfNot(VT) && N1.hasOneUse() && isBitwiseNot(N1)) {
SDValue Add = DAG.getNode(ISD::ADD, DL, VT, N0, N1.getOperand(0));
return DAG.getNode(ISD::ADD, DL, VT, Add, DAG.getConstant(1, DL, VT));
}
// Hoist one-use addition by non-opaque constant:
// (x + C) - y -> (x - y) + C
if (N0.hasOneUse() && N0.getOpcode() == ISD::ADD &&
isConstantOrConstantVector(N0.getOperand(1), /*NoOpaques=*/true)) {
SDValue Sub = DAG.getNode(ISD::SUB, DL, VT, N0.getOperand(0), N1);
return DAG.getNode(ISD::ADD, DL, VT, Sub, N0.getOperand(1));
}
// y - (x + C) -> (y - x) - C
if (N1.hasOneUse() && N1.getOpcode() == ISD::ADD &&
isConstantOrConstantVector(N1.getOperand(1), /*NoOpaques=*/true)) {
SDValue Sub = DAG.getNode(ISD::SUB, DL, VT, N0, N1.getOperand(0));
return DAG.getNode(ISD::SUB, DL, VT, Sub, N1.getOperand(1));
}
// (x - C) - y -> (x - y) - C
// This is necessary because SUB(X,C) -> ADD(X,-C) doesn't work for vectors.
if (N0.hasOneUse() && N0.getOpcode() == ISD::SUB &&
isConstantOrConstantVector(N0.getOperand(1), /*NoOpaques=*/true)) {
SDValue Sub = DAG.getNode(ISD::SUB, DL, VT, N0.getOperand(0), N1);
return DAG.getNode(ISD::SUB, DL, VT, Sub, N0.getOperand(1));
}
// (C - x) - y -> C - (x + y)
if (N0.hasOneUse() && N0.getOpcode() == ISD::SUB &&
isConstantOrConstantVector(N0.getOperand(0), /*NoOpaques=*/true)) {
SDValue Add = DAG.getNode(ISD::ADD, DL, VT, N0.getOperand(1), N1);
return DAG.getNode(ISD::SUB, DL, VT, N0.getOperand(0), Add);
}
// If the target's bool is represented as 0/-1, prefer to make this 'add 0/-1'
// rather than 'sub 0/1' (the sext should get folded).
// sub X, (zext i1 Y) --> add X, (sext i1 Y)
if (N1.getOpcode() == ISD::ZERO_EXTEND &&
N1.getOperand(0).getScalarValueSizeInBits() == 1 &&
TLI.getBooleanContents(VT) ==
TargetLowering::ZeroOrNegativeOneBooleanContent) {
SDValue SExt = DAG.getNode(ISD::SIGN_EXTEND, DL, VT, N1.getOperand(0));
return DAG.getNode(ISD::ADD, DL, VT, N0, SExt);
}
// fold Y = sra (X, size(X)-1); sub (xor (X, Y), Y) -> (abs X)
if (TLI.isOperationLegalOrCustom(ISD::ABS, VT)) {
if (N0.getOpcode() == ISD::XOR && N1.getOpcode() == ISD::SRA) {
SDValue X0 = N0.getOperand(0), X1 = N0.getOperand(1);
SDValue S0 = N1.getOperand(0);
if ((X0 == S0 && X1 == N1) || (X0 == N1 && X1 == S0))
if (ConstantSDNode *C = isConstOrConstSplat(N1.getOperand(1)))
if (C->getAPIntValue() == (VT.getScalarSizeInBits() - 1))
return DAG.getNode(ISD::ABS, SDLoc(N), VT, S0);
}
}
// If the relocation model supports it, consider symbol offsets.
if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(N0))
if (!LegalOperations && TLI.isOffsetFoldingLegal(GA)) {
// fold (sub Sym, c) -> Sym-c
if (N1C && GA->getOpcode() == ISD::GlobalAddress)
return DAG.getGlobalAddress(GA->getGlobal(), SDLoc(N1C), VT,
GA->getOffset() -
(uint64_t)N1C->getSExtValue());
// fold (sub Sym+c1, Sym+c2) -> c1-c2
if (GlobalAddressSDNode *GB = dyn_cast<GlobalAddressSDNode>(N1))
if (GA->getGlobal() == GB->getGlobal())
return DAG.getConstant((uint64_t)GA->getOffset() - GB->getOffset(),
DL, VT);
}
// sub X, (sextinreg Y i1) -> add X, (and Y 1)
if (N1.getOpcode() == ISD::SIGN_EXTEND_INREG) {
VTSDNode *TN = cast<VTSDNode>(N1.getOperand(1));
if (TN->getVT() == MVT::i1) {
SDValue ZExt = DAG.getNode(ISD::AND, DL, VT, N1.getOperand(0),
DAG.getConstant(1, DL, VT));
return DAG.getNode(ISD::ADD, DL, VT, N0, ZExt);
}
}
// canonicalize (sub X, (vscale * C)) to (add X, (vscale * -C))
if (N1.getOpcode() == ISD::VSCALE) {
const APInt &IntVal = N1.getConstantOperandAPInt(0);
return DAG.getNode(ISD::ADD, DL, VT, N0, DAG.getVScale(DL, VT, -IntVal));
}
// canonicalize (sub X, step_vector(C)) to (add X, step_vector(-C))
if (N1.getOpcode() == ISD::STEP_VECTOR && N1.hasOneUse()) {
APInt NewStep = -N1.getConstantOperandAPInt(0);
return DAG.getNode(ISD::ADD, DL, VT, N0,
DAG.getStepVector(DL, VT, NewStep));
}
// Prefer an add for more folding potential and possibly better codegen:
// sub N0, (lshr N10, width-1) --> add N0, (ashr N10, width-1)
if (!LegalOperations && N1.getOpcode() == ISD::SRL && N1.hasOneUse()) {
SDValue ShAmt = N1.getOperand(1);
ConstantSDNode *ShAmtC = isConstOrConstSplat(ShAmt);
if (ShAmtC &&
ShAmtC->getAPIntValue() == (N1.getScalarValueSizeInBits() - 1)) {
SDValue SRA = DAG.getNode(ISD::SRA, DL, VT, N1.getOperand(0), ShAmt);
return DAG.getNode(ISD::ADD, DL, VT, N0, SRA);
}
}
// As with the previous fold, prefer add for more folding potential.
// Subtracting SMIN/0 is the same as adding SMIN/0:
// N0 - (X << BW-1) --> N0 + (X << BW-1)
if (N1.getOpcode() == ISD::SHL) {
ConstantSDNode *ShlC = isConstOrConstSplat(N1.getOperand(1));
if (ShlC && ShlC->getAPIntValue() == VT.getScalarSizeInBits() - 1)
return DAG.getNode(ISD::ADD, DL, VT, N1, N0);
}
if (TLI.isOperationLegalOrCustom(ISD::ADDCARRY, VT)) {
// (sub Carry, X) -> (addcarry (sub 0, X), 0, Carry)
if (SDValue Carry = getAsCarry(TLI, N0)) {
SDValue X = N1;
SDValue Zero = DAG.getConstant(0, DL, VT);
SDValue NegX = DAG.getNode(ISD::SUB, DL, VT, Zero, X);
return DAG.getNode(ISD::ADDCARRY, DL,
DAG.getVTList(VT, Carry.getValueType()), NegX, Zero,
Carry);
}
}
return SDValue();
}
SDValue DAGCombiner::visitSUBSAT(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
SDLoc DL(N);
// fold (sub_sat x, undef) -> 0
if (N0.isUndef() || N1.isUndef())
return DAG.getConstant(0, DL, VT);
// fold (sub_sat x, x) -> 0
if (N0 == N1)
return DAG.getConstant(0, DL, VT);
// fold (sub_sat c1, c2) -> c3
if (SDValue C = DAG.FoldConstantArithmetic(N->getOpcode(), DL, VT, {N0, N1}))
return C;
// fold vector ops
if (VT.isVector()) {
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
// fold (sub_sat x, 0) -> x, vector edition
if (ISD::isConstantSplatVectorAllZeros(N1.getNode()))
return N0;
}
// fold (sub_sat x, 0) -> x
if (isNullConstant(N1))
return N0;
return SDValue();
}
SDValue DAGCombiner::visitSUBC(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
SDLoc DL(N);
// If the flag result is dead, turn this into an SUB.
if (!N->hasAnyUseOfValue(1))
return CombineTo(N, DAG.getNode(ISD::SUB, DL, VT, N0, N1),
DAG.getNode(ISD::CARRY_FALSE, DL, MVT::Glue));
// fold (subc x, x) -> 0 + no borrow
if (N0 == N1)
return CombineTo(N, DAG.getConstant(0, DL, VT),
DAG.getNode(ISD::CARRY_FALSE, DL, MVT::Glue));
// fold (subc x, 0) -> x + no borrow
if (isNullConstant(N1))
return CombineTo(N, N0, DAG.getNode(ISD::CARRY_FALSE, DL, MVT::Glue));
// Canonicalize (sub -1, x) -> ~x, i.e. (xor x, -1) + no borrow
if (isAllOnesConstant(N0))
return CombineTo(N, DAG.getNode(ISD::XOR, DL, VT, N1, N0),
DAG.getNode(ISD::CARRY_FALSE, DL, MVT::Glue));
return SDValue();
}
SDValue DAGCombiner::visitSUBO(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
bool IsSigned = (ISD::SSUBO == N->getOpcode());
EVT CarryVT = N->getValueType(1);
SDLoc DL(N);
// If the flag result is dead, turn this into an SUB.
if (!N->hasAnyUseOfValue(1))
return CombineTo(N, DAG.getNode(ISD::SUB, DL, VT, N0, N1),
DAG.getUNDEF(CarryVT));
// fold (subo x, x) -> 0 + no borrow
if (N0 == N1)
return CombineTo(N, DAG.getConstant(0, DL, VT),
DAG.getConstant(0, DL, CarryVT));
ConstantSDNode *N1C = getAsNonOpaqueConstant(N1);
// fold (subox, c) -> (addo x, -c)
if (IsSigned && N1C && !N1C->getAPIntValue().isMinSignedValue()) {
return DAG.getNode(ISD::SADDO, DL, N->getVTList(), N0,
DAG.getConstant(-N1C->getAPIntValue(), DL, VT));
}
// fold (subo x, 0) -> x + no borrow
if (isNullOrNullSplat(N1))
return CombineTo(N, N0, DAG.getConstant(0, DL, CarryVT));
// Canonicalize (usubo -1, x) -> ~x, i.e. (xor x, -1) + no borrow
if (!IsSigned && isAllOnesOrAllOnesSplat(N0))
return CombineTo(N, DAG.getNode(ISD::XOR, DL, VT, N1, N0),
DAG.getConstant(0, DL, CarryVT));
return SDValue();
}
SDValue DAGCombiner::visitSUBE(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue CarryIn = N->getOperand(2);
// fold (sube x, y, false) -> (subc x, y)
if (CarryIn.getOpcode() == ISD::CARRY_FALSE)
return DAG.getNode(ISD::SUBC, SDLoc(N), N->getVTList(), N0, N1);
return SDValue();
}
SDValue DAGCombiner::visitSUBCARRY(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue CarryIn = N->getOperand(2);
// fold (subcarry x, y, false) -> (usubo x, y)
if (isNullConstant(CarryIn)) {
if (!LegalOperations ||
TLI.isOperationLegalOrCustom(ISD::USUBO, N->getValueType(0)))
return DAG.getNode(ISD::USUBO, SDLoc(N), N->getVTList(), N0, N1);
}
return SDValue();
}
SDValue DAGCombiner::visitSSUBO_CARRY(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue CarryIn = N->getOperand(2);
// fold (ssubo_carry x, y, false) -> (ssubo x, y)
if (isNullConstant(CarryIn)) {
if (!LegalOperations ||
TLI.isOperationLegalOrCustom(ISD::SSUBO, N->getValueType(0)))
return DAG.getNode(ISD::SSUBO, SDLoc(N), N->getVTList(), N0, N1);
}
return SDValue();
}
// Notice that "mulfix" can be any of SMULFIX, SMULFIXSAT, UMULFIX and
// UMULFIXSAT here.
SDValue DAGCombiner::visitMULFIX(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue Scale = N->getOperand(2);
EVT VT = N0.getValueType();
// fold (mulfix x, undef, scale) -> 0
if (N0.isUndef() || N1.isUndef())
return DAG.getConstant(0, SDLoc(N), VT);
// Canonicalize constant to RHS (vector doesn't have to splat)
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(N->getOpcode(), SDLoc(N), VT, N1, N0, Scale);
// fold (mulfix x, 0, scale) -> 0
if (isNullConstant(N1))
return DAG.getConstant(0, SDLoc(N), VT);
return SDValue();
}
SDValue DAGCombiner::visitMUL(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
SDLoc DL(N);
// fold (mul x, undef) -> 0
if (N0.isUndef() || N1.isUndef())
return DAG.getConstant(0, DL, VT);
// fold (mul c1, c2) -> c1*c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::MUL, DL, VT, {N0, N1}))
return C;
// canonicalize constant to RHS (vector doesn't have to splat)
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(ISD::MUL, DL, VT, N1, N0);
bool N1IsConst = false;
bool N1IsOpaqueConst = false;
APInt ConstValue1;
// fold vector ops
if (VT.isVector()) {
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
N1IsConst = ISD::isConstantSplatVector(N1.getNode(), ConstValue1);
assert((!N1IsConst ||
ConstValue1.getBitWidth() == VT.getScalarSizeInBits()) &&
"Splat APInt should be element width");
} else {
N1IsConst = isa<ConstantSDNode>(N1);
if (N1IsConst) {
ConstValue1 = cast<ConstantSDNode>(N1)->getAPIntValue();
N1IsOpaqueConst = cast<ConstantSDNode>(N1)->isOpaque();
}
}
// fold (mul x, 0) -> 0
if (N1IsConst && ConstValue1.isZero())
return N1;
// fold (mul x, 1) -> x
if (N1IsConst && ConstValue1.isOne())
return N0;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
// fold (mul x, -1) -> 0-x
if (N1IsConst && ConstValue1.isAllOnes())
return DAG.getNode(ISD::SUB, DL, VT,
DAG.getConstant(0, DL, VT), N0);
// fold (mul x, (1 << c)) -> x << c
if (isConstantOrConstantVector(N1, /*NoOpaques*/ true) &&
DAG.isKnownToBeAPowerOfTwo(N1) &&
(!VT.isVector() || Level <= AfterLegalizeVectorOps)) {
SDValue LogBase2 = BuildLogBase2(N1, DL);
EVT ShiftVT = getShiftAmountTy(N0.getValueType());
SDValue Trunc = DAG.getZExtOrTrunc(LogBase2, DL, ShiftVT);
return DAG.getNode(ISD::SHL, DL, VT, N0, Trunc);
}
// fold (mul x, -(1 << c)) -> -(x << c) or (-x) << c
if (N1IsConst && !N1IsOpaqueConst && ConstValue1.isNegatedPowerOf2()) {
unsigned Log2Val = (-ConstValue1).logBase2();
// FIXME: If the input is something that is easily negated (e.g. a
// single-use add), we should put the negate there.
return DAG.getNode(ISD::SUB, DL, VT,
DAG.getConstant(0, DL, VT),
DAG.getNode(ISD::SHL, DL, VT, N0,
DAG.getConstant(Log2Val, DL,
getShiftAmountTy(N0.getValueType()))));
}
// Try to transform:
// (1) multiply-by-(power-of-2 +/- 1) into shift and add/sub.
// mul x, (2^N + 1) --> add (shl x, N), x
// mul x, (2^N - 1) --> sub (shl x, N), x
// Examples: x * 33 --> (x << 5) + x
// x * 15 --> (x << 4) - x
// x * -33 --> -((x << 5) + x)
// x * -15 --> -((x << 4) - x) ; this reduces --> x - (x << 4)
// (2) multiply-by-(power-of-2 +/- power-of-2) into shifts and add/sub.
// mul x, (2^N + 2^M) --> (add (shl x, N), (shl x, M))
// mul x, (2^N - 2^M) --> (sub (shl x, N), (shl x, M))
// Examples: x * 0x8800 --> (x << 15) + (x << 11)
// x * 0xf800 --> (x << 16) - (x << 11)
// x * -0x8800 --> -((x << 15) + (x << 11))
// x * -0xf800 --> -((x << 16) - (x << 11)) ; (x << 11) - (x << 16)
if (N1IsConst && TLI.decomposeMulByConstant(*DAG.getContext(), VT, N1)) {
// TODO: We could handle more general decomposition of any constant by
// having the target set a limit on number of ops and making a
// callback to determine that sequence (similar to sqrt expansion).
unsigned MathOp = ISD::DELETED_NODE;
APInt MulC = ConstValue1.abs();
// The constant `2` should be treated as (2^0 + 1).
unsigned TZeros = MulC == 2 ? 0 : MulC.countTrailingZeros();
MulC.lshrInPlace(TZeros);
if ((MulC - 1).isPowerOf2())
MathOp = ISD::ADD;
else if ((MulC + 1).isPowerOf2())
MathOp = ISD::SUB;
if (MathOp != ISD::DELETED_NODE) {
unsigned ShAmt =
MathOp == ISD::ADD ? (MulC - 1).logBase2() : (MulC + 1).logBase2();
ShAmt += TZeros;
assert(ShAmt < VT.getScalarSizeInBits() &&
"multiply-by-constant generated out of bounds shift");
SDValue Shl =
DAG.getNode(ISD::SHL, DL, VT, N0, DAG.getConstant(ShAmt, DL, VT));
SDValue R =
TZeros ? DAG.getNode(MathOp, DL, VT, Shl,
DAG.getNode(ISD::SHL, DL, VT, N0,
DAG.getConstant(TZeros, DL, VT)))
: DAG.getNode(MathOp, DL, VT, Shl, N0);
if (ConstValue1.isNegative())
R = DAG.getNode(ISD::SUB, DL, VT, DAG.getConstant(0, DL, VT), R);
return R;
}
}
// (mul (shl X, c1), c2) -> (mul X, c2 << c1)
if (N0.getOpcode() == ISD::SHL) {
SDValue N01 = N0.getOperand(1);
if (SDValue C3 = DAG.FoldConstantArithmetic(ISD::SHL, DL, VT, {N1, N01}))
return DAG.getNode(ISD::MUL, DL, VT, N0.getOperand(0), C3);
}
// Change (mul (shl X, C), Y) -> (shl (mul X, Y), C) when the shift has one
// use.
{
SDValue Sh, Y;
// Check for both (mul (shl X, C), Y) and (mul Y, (shl X, C)).
if (N0.getOpcode() == ISD::SHL &&
isConstantOrConstantVector(N0.getOperand(1)) && N0->hasOneUse()) {
Sh = N0; Y = N1;
} else if (N1.getOpcode() == ISD::SHL &&
isConstantOrConstantVector(N1.getOperand(1)) &&
N1->hasOneUse()) {
Sh = N1; Y = N0;
}
if (Sh.getNode()) {
SDValue Mul = DAG.getNode(ISD::MUL, DL, VT, Sh.getOperand(0), Y);
return DAG.getNode(ISD::SHL, DL, VT, Mul, Sh.getOperand(1));
}
}
// fold (mul (add x, c1), c2) -> (add (mul x, c2), c1*c2)
if (DAG.isConstantIntBuildVectorOrConstantInt(N1) &&
N0.getOpcode() == ISD::ADD &&
DAG.isConstantIntBuildVectorOrConstantInt(N0.getOperand(1)) &&
isMulAddWithConstProfitable(N, N0, N1))
return DAG.getNode(
ISD::ADD, DL, VT,
DAG.getNode(ISD::MUL, SDLoc(N0), VT, N0.getOperand(0), N1),
DAG.getNode(ISD::MUL, SDLoc(N1), VT, N0.getOperand(1), N1));
// Fold (mul (vscale * C0), C1) to (vscale * (C0 * C1)).
if (N0.getOpcode() == ISD::VSCALE)
if (ConstantSDNode *NC1 = isConstOrConstSplat(N1)) {
const APInt &C0 = N0.getConstantOperandAPInt(0);
const APInt &C1 = NC1->getAPIntValue();
return DAG.getVScale(DL, VT, C0 * C1);
}
// Fold (mul step_vector(C0), C1) to (step_vector(C0 * C1)).
APInt MulVal;
if (N0.getOpcode() == ISD::STEP_VECTOR)
if (ISD::isConstantSplatVector(N1.getNode(), MulVal)) {
const APInt &C0 = N0.getConstantOperandAPInt(0);
APInt NewStep = C0 * MulVal;
return DAG.getStepVector(DL, VT, NewStep);
}
// Fold ((mul x, 0/undef) -> 0,
// (mul x, 1) -> x) -> x)
// -> and(x, mask)
// We can replace vectors with '0' and '1' factors with a clearing mask.
if (VT.isFixedLengthVector()) {
unsigned NumElts = VT.getVectorNumElements();
SmallBitVector ClearMask;
ClearMask.reserve(NumElts);
auto IsClearMask = [&ClearMask](ConstantSDNode *V) {
if (!V || V->isZero()) {
ClearMask.push_back(true);
return true;
}
ClearMask.push_back(false);
return V->isOne();
};
if ((!LegalOperations || TLI.isOperationLegalOrCustom(ISD::AND, VT)) &&
ISD::matchUnaryPredicate(N1, IsClearMask, /*AllowUndefs*/ true)) {
assert(N1.getOpcode() == ISD::BUILD_VECTOR && "Unknown constant vector");
EVT LegalSVT = N1.getOperand(0).getValueType();
SDValue Zero = DAG.getConstant(0, DL, LegalSVT);
SDValue AllOnes = DAG.getAllOnesConstant(DL, LegalSVT);
SmallVector<SDValue, 16> Mask(NumElts, AllOnes);
for (unsigned I = 0; I != NumElts; ++I)
if (ClearMask[I])
Mask[I] = Zero;
return DAG.getNode(ISD::AND, DL, VT, N0, DAG.getBuildVector(VT, DL, Mask));
}
}
// reassociate mul
if (SDValue RMUL = reassociateOps(ISD::MUL, DL, N0, N1, N->getFlags()))
return RMUL;
return SDValue();
}
/// Return true if divmod libcall is available.
static bool isDivRemLibcallAvailable(SDNode *Node, bool isSigned,
const TargetLowering &TLI) {
RTLIB::Libcall LC;
EVT NodeType = Node->getValueType(0);
if (!NodeType.isSimple())
return false;
switch (NodeType.getSimpleVT().SimpleTy) {
default: return false; // No libcall for vector types.
case MVT::i8: LC= isSigned ? RTLIB::SDIVREM_I8 : RTLIB::UDIVREM_I8; break;
case MVT::i16: LC= isSigned ? RTLIB::SDIVREM_I16 : RTLIB::UDIVREM_I16; break;
case MVT::i32: LC= isSigned ? RTLIB::SDIVREM_I32 : RTLIB::UDIVREM_I32; break;
case MVT::i64: LC= isSigned ? RTLIB::SDIVREM_I64 : RTLIB::UDIVREM_I64; break;
case MVT::i128: LC= isSigned ? RTLIB::SDIVREM_I128:RTLIB::UDIVREM_I128; break;
}
return TLI.getLibcallName(LC) != nullptr;
}
/// Issue divrem if both quotient and remainder are needed.
SDValue DAGCombiner::useDivRem(SDNode *Node) {
if (Node->use_empty())
return SDValue(); // This is a dead node, leave it alone.
unsigned Opcode = Node->getOpcode();
bool isSigned = (Opcode == ISD::SDIV) || (Opcode == ISD::SREM);
unsigned DivRemOpc = isSigned ? ISD::SDIVREM : ISD::UDIVREM;
// DivMod lib calls can still work on non-legal types if using lib-calls.
EVT VT = Node->getValueType(0);
if (VT.isVector() || !VT.isInteger())
return SDValue();
if (!TLI.isTypeLegal(VT) && !TLI.isOperationCustom(DivRemOpc, VT))
return SDValue();
// If DIVREM is going to get expanded into a libcall,
// but there is no libcall available, then don't combine.
if (!TLI.isOperationLegalOrCustom(DivRemOpc, VT) &&
!isDivRemLibcallAvailable(Node, isSigned, TLI))
return SDValue();
// If div is legal, it's better to do the normal expansion
unsigned OtherOpcode = 0;
if ((Opcode == ISD::SDIV) || (Opcode == ISD::UDIV)) {
OtherOpcode = isSigned ? ISD::SREM : ISD::UREM;
if (TLI.isOperationLegalOrCustom(Opcode, VT))
return SDValue();
} else {
OtherOpcode = isSigned ? ISD::SDIV : ISD::UDIV;
if (TLI.isOperationLegalOrCustom(OtherOpcode, VT))
return SDValue();
}
SDValue Op0 = Node->getOperand(0);
SDValue Op1 = Node->getOperand(1);
SDValue combined;
for (SDNode *User : Op0->uses()) {
if (User == Node || User->getOpcode() == ISD::DELETED_NODE ||
User->use_empty())
continue;
// Convert the other matching node(s), too;
// otherwise, the DIVREM may get target-legalized into something
// target-specific that we won't be able to recognize.
unsigned UserOpc = User->getOpcode();
if ((UserOpc == Opcode || UserOpc == OtherOpcode || UserOpc == DivRemOpc) &&
User->getOperand(0) == Op0 &&
User->getOperand(1) == Op1) {
if (!combined) {
if (UserOpc == OtherOpcode) {
SDVTList VTs = DAG.getVTList(VT, VT);
combined = DAG.getNode(DivRemOpc, SDLoc(Node), VTs, Op0, Op1);
} else if (UserOpc == DivRemOpc) {
combined = SDValue(User, 0);
} else {
assert(UserOpc == Opcode);
continue;
}
}
if (UserOpc == ISD::SDIV || UserOpc == ISD::UDIV)
CombineTo(User, combined);
else if (UserOpc == ISD::SREM || UserOpc == ISD::UREM)
CombineTo(User, combined.getValue(1));
}
}
return combined;
}
static SDValue simplifyDivRem(SDNode *N, SelectionDAG &DAG) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
SDLoc DL(N);
unsigned Opc = N->getOpcode();
bool IsDiv = (ISD::SDIV == Opc) || (ISD::UDIV == Opc);
ConstantSDNode *N1C = isConstOrConstSplat(N1);
// X / undef -> undef
// X % undef -> undef
// X / 0 -> undef
// X % 0 -> undef
// NOTE: This includes vectors where any divisor element is zero/undef.
if (DAG.isUndef(Opc, {N0, N1}))
return DAG.getUNDEF(VT);
// undef / X -> 0
// undef % X -> 0
if (N0.isUndef())
return DAG.getConstant(0, DL, VT);
// 0 / X -> 0
// 0 % X -> 0
ConstantSDNode *N0C = isConstOrConstSplat(N0);
if (N0C && N0C->isZero())
return N0;
// X / X -> 1
// X % X -> 0
if (N0 == N1)
return DAG.getConstant(IsDiv ? 1 : 0, DL, VT);
// X / 1 -> X
// X % 1 -> 0
// If this is a boolean op (single-bit element type), we can't have
// division-by-zero or remainder-by-zero, so assume the divisor is 1.
// TODO: Similarly, if we're zero-extending a boolean divisor, then assume
// it's a 1.
if ((N1C && N1C->isOne()) || (VT.getScalarType() == MVT::i1))
return IsDiv ? N0 : DAG.getConstant(0, DL, VT);
return SDValue();
}
SDValue DAGCombiner::visitSDIV(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
EVT CCVT = getSetCCResultType(VT);
SDLoc DL(N);
// fold (sdiv c1, c2) -> c1/c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::SDIV, DL, VT, {N0, N1}))
return C;
// fold vector ops
if (VT.isVector())
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
// fold (sdiv X, -1) -> 0-X
ConstantSDNode *N1C = isConstOrConstSplat(N1);
if (N1C && N1C->isAllOnes())
return DAG.getNode(ISD::SUB, DL, VT, DAG.getConstant(0, DL, VT), N0);
// fold (sdiv X, MIN_SIGNED) -> select(X == MIN_SIGNED, 1, 0)
if (N1C && N1C->getAPIntValue().isMinSignedValue())
return DAG.getSelect(DL, VT, DAG.getSetCC(DL, CCVT, N0, N1, ISD::SETEQ),
DAG.getConstant(1, DL, VT),
DAG.getConstant(0, DL, VT));
if (SDValue V = simplifyDivRem(N, DAG))
return V;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
// If we know the sign bits of both operands are zero, strength reduce to a
// udiv instead. Handles (X&15) /s 4 -> X&15 >> 2
if (DAG.SignBitIsZero(N1) && DAG.SignBitIsZero(N0))
return DAG.getNode(ISD::UDIV, DL, N1.getValueType(), N0, N1);
if (SDValue V = visitSDIVLike(N0, N1, N)) {
// If the corresponding remainder node exists, update its users with
// (Dividend - (Quotient * Divisor).
if (SDNode *RemNode = DAG.getNodeIfExists(ISD::SREM, N->getVTList(),
{ N0, N1 })) {
SDValue Mul = DAG.getNode(ISD::MUL, DL, VT, V, N1);
SDValue Sub = DAG.getNode(ISD::SUB, DL, VT, N0, Mul);
AddToWorklist(Mul.getNode());
AddToWorklist(Sub.getNode());
CombineTo(RemNode, Sub);
}
return V;
}
// sdiv, srem -> sdivrem
// If the divisor is constant, then return DIVREM only if isIntDivCheap() is
// true. Otherwise, we break the simplification logic in visitREM().
AttributeList Attr = DAG.getMachineFunction().getFunction().getAttributes();
if (!N1C || TLI.isIntDivCheap(N->getValueType(0), Attr))
if (SDValue DivRem = useDivRem(N))
return DivRem;
return SDValue();
}
static bool isDivisorPowerOfTwo(SDValue Divisor) {
// Helper for determining whether a value is a power-2 constant scalar or a
// vector of such elements.
auto IsPowerOfTwo = [](ConstantSDNode *C) {
if (C->isZero() || C->isOpaque())
return false;
if (C->getAPIntValue().isPowerOf2())
return true;
if (C->getAPIntValue().isNegatedPowerOf2())
return true;
return false;
};
return ISD::matchUnaryPredicate(Divisor, IsPowerOfTwo);
}
SDValue DAGCombiner::visitSDIVLike(SDValue N0, SDValue N1, SDNode *N) {
SDLoc DL(N);
EVT VT = N->getValueType(0);
EVT CCVT = getSetCCResultType(VT);
unsigned BitWidth = VT.getScalarSizeInBits();
// fold (sdiv X, pow2) -> simple ops after legalize
// FIXME: We check for the exact bit here because the generic lowering gives
// better results in that case. The target-specific lowering should learn how
// to handle exact sdivs efficiently.
if (!N->getFlags().hasExact() && isDivisorPowerOfTwo(N1)) {
// Target-specific implementation of sdiv x, pow2.
if (SDValue Res = BuildSDIVPow2(N))
return Res;
// Create constants that are functions of the shift amount value.
EVT ShiftAmtTy = getShiftAmountTy(N0.getValueType());
SDValue Bits = DAG.getConstant(BitWidth, DL, ShiftAmtTy);
SDValue C1 = DAG.getNode(ISD::CTTZ, DL, VT, N1);
C1 = DAG.getZExtOrTrunc(C1, DL, ShiftAmtTy);
SDValue Inexact = DAG.getNode(ISD::SUB, DL, ShiftAmtTy, Bits, C1);
if (!isConstantOrConstantVector(Inexact))
return SDValue();
// Splat the sign bit into the register
SDValue Sign = DAG.getNode(ISD::SRA, DL, VT, N0,
DAG.getConstant(BitWidth - 1, DL, ShiftAmtTy));
AddToWorklist(Sign.getNode());
// Add (N0 < 0) ? abs2 - 1 : 0;
SDValue Srl = DAG.getNode(ISD::SRL, DL, VT, Sign, Inexact);
AddToWorklist(Srl.getNode());
SDValue Add = DAG.getNode(ISD::ADD, DL, VT, N0, Srl);
AddToWorklist(Add.getNode());
SDValue Sra = DAG.getNode(ISD::SRA, DL, VT, Add, C1);
AddToWorklist(Sra.getNode());
// Special case: (sdiv X, 1) -> X
// Special Case: (sdiv X, -1) -> 0-X
SDValue One = DAG.getConstant(1, DL, VT);
SDValue AllOnes = DAG.getAllOnesConstant(DL, VT);
SDValue IsOne = DAG.getSetCC(DL, CCVT, N1, One, ISD::SETEQ);
SDValue IsAllOnes = DAG.getSetCC(DL, CCVT, N1, AllOnes, ISD::SETEQ);
SDValue IsOneOrAllOnes = DAG.getNode(ISD::OR, DL, CCVT, IsOne, IsAllOnes);
Sra = DAG.getSelect(DL, VT, IsOneOrAllOnes, N0, Sra);
// If dividing by a positive value, we're done. Otherwise, the result must
// be negated.
SDValue Zero = DAG.getConstant(0, DL, VT);
SDValue Sub = DAG.getNode(ISD::SUB, DL, VT, Zero, Sra);
// FIXME: Use SELECT_CC once we improve SELECT_CC constant-folding.
SDValue IsNeg = DAG.getSetCC(DL, CCVT, N1, Zero, ISD::SETLT);
SDValue Res = DAG.getSelect(DL, VT, IsNeg, Sub, Sra);
return Res;
}
// If integer divide is expensive and we satisfy the requirements, emit an
// alternate sequence. Targets may check function attributes for size/speed
// trade-offs.
AttributeList Attr = DAG.getMachineFunction().getFunction().getAttributes();
if (isConstantOrConstantVector(N1) &&
!TLI.isIntDivCheap(N->getValueType(0), Attr))
if (SDValue Op = BuildSDIV(N))
return Op;
return SDValue();
}
SDValue DAGCombiner::visitUDIV(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
EVT CCVT = getSetCCResultType(VT);
SDLoc DL(N);
// fold (udiv c1, c2) -> c1/c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::UDIV, DL, VT, {N0, N1}))
return C;
// fold vector ops
if (VT.isVector())
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
// fold (udiv X, -1) -> select(X == -1, 1, 0)
ConstantSDNode *N1C = isConstOrConstSplat(N1);
if (N1C && N1C->isAllOnes())
return DAG.getSelect(DL, VT, DAG.getSetCC(DL, CCVT, N0, N1, ISD::SETEQ),
DAG.getConstant(1, DL, VT),
DAG.getConstant(0, DL, VT));
if (SDValue V = simplifyDivRem(N, DAG))
return V;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
if (SDValue V = visitUDIVLike(N0, N1, N)) {
// If the corresponding remainder node exists, update its users with
// (Dividend - (Quotient * Divisor).
if (SDNode *RemNode = DAG.getNodeIfExists(ISD::UREM, N->getVTList(),
{ N0, N1 })) {
SDValue Mul = DAG.getNode(ISD::MUL, DL, VT, V, N1);
SDValue Sub = DAG.getNode(ISD::SUB, DL, VT, N0, Mul);
AddToWorklist(Mul.getNode());
AddToWorklist(Sub.getNode());
CombineTo(RemNode, Sub);
}
return V;
}
// sdiv, srem -> sdivrem
// If the divisor is constant, then return DIVREM only if isIntDivCheap() is
// true. Otherwise, we break the simplification logic in visitREM().
AttributeList Attr = DAG.getMachineFunction().getFunction().getAttributes();
if (!N1C || TLI.isIntDivCheap(N->getValueType(0), Attr))
if (SDValue DivRem = useDivRem(N))
return DivRem;
return SDValue();
}
SDValue DAGCombiner::visitUDIVLike(SDValue N0, SDValue N1, SDNode *N) {
SDLoc DL(N);
EVT VT = N->getValueType(0);
// fold (udiv x, (1 << c)) -> x >>u c
if (isConstantOrConstantVector(N1, /*NoOpaques*/ true) &&
DAG.isKnownToBeAPowerOfTwo(N1)) {
SDValue LogBase2 = BuildLogBase2(N1, DL);
AddToWorklist(LogBase2.getNode());
EVT ShiftVT = getShiftAmountTy(N0.getValueType());
SDValue Trunc = DAG.getZExtOrTrunc(LogBase2, DL, ShiftVT);
AddToWorklist(Trunc.getNode());
return DAG.getNode(ISD::SRL, DL, VT, N0, Trunc);
}
// fold (udiv x, (shl c, y)) -> x >>u (log2(c)+y) iff c is power of 2
if (N1.getOpcode() == ISD::SHL) {
SDValue N10 = N1.getOperand(0);
if (isConstantOrConstantVector(N10, /*NoOpaques*/ true) &&
DAG.isKnownToBeAPowerOfTwo(N10)) {
SDValue LogBase2 = BuildLogBase2(N10, DL);
AddToWorklist(LogBase2.getNode());
EVT ADDVT = N1.getOperand(1).getValueType();
SDValue Trunc = DAG.getZExtOrTrunc(LogBase2, DL, ADDVT);
AddToWorklist(Trunc.getNode());
SDValue Add = DAG.getNode(ISD::ADD, DL, ADDVT, N1.getOperand(1), Trunc);
AddToWorklist(Add.getNode());
return DAG.getNode(ISD::SRL, DL, VT, N0, Add);
}
}
// fold (udiv x, c) -> alternate
AttributeList Attr = DAG.getMachineFunction().getFunction().getAttributes();
if (isConstantOrConstantVector(N1) &&
!TLI.isIntDivCheap(N->getValueType(0), Attr))
if (SDValue Op = BuildUDIV(N))
return Op;
return SDValue();
}
SDValue DAGCombiner::buildOptimizedSREM(SDValue N0, SDValue N1, SDNode *N) {
if (!N->getFlags().hasExact() && isDivisorPowerOfTwo(N1) &&
!DAG.doesNodeExist(ISD::SDIV, N->getVTList(), {N0, N1})) {
// Target-specific implementation of srem x, pow2.
if (SDValue Res = BuildSREMPow2(N))
return Res;
}
return SDValue();
}
// handles ISD::SREM and ISD::UREM
SDValue DAGCombiner::visitREM(SDNode *N) {
unsigned Opcode = N->getOpcode();
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
EVT CCVT = getSetCCResultType(VT);
bool isSigned = (Opcode == ISD::SREM);
SDLoc DL(N);
// fold (rem c1, c2) -> c1%c2
ConstantSDNode *N1C = isConstOrConstSplat(N1);
if (SDValue C = DAG.FoldConstantArithmetic(Opcode, DL, VT, {N0, N1}))
return C;
// fold (urem X, -1) -> select(FX == -1, 0, FX)
// Freeze the numerator to avoid a miscompile with an undefined value.
if (!isSigned && N1C && N1C->isAllOnes()) {
SDValue F0 = DAG.getFreeze(N0);
SDValue EqualsNeg1 = DAG.getSetCC(DL, CCVT, F0, N1, ISD::SETEQ);
return DAG.getSelect(DL, VT, EqualsNeg1, DAG.getConstant(0, DL, VT), F0);
}
if (SDValue V = simplifyDivRem(N, DAG))
return V;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
if (isSigned) {
// If we know the sign bits of both operands are zero, strength reduce to a
// urem instead. Handles (X & 0x0FFFFFFF) %s 16 -> X&15
if (DAG.SignBitIsZero(N1) && DAG.SignBitIsZero(N0))
return DAG.getNode(ISD::UREM, DL, VT, N0, N1);
} else {
if (DAG.isKnownToBeAPowerOfTwo(N1)) {
// fold (urem x, pow2) -> (and x, pow2-1)
SDValue NegOne = DAG.getAllOnesConstant(DL, VT);
SDValue Add = DAG.getNode(ISD::ADD, DL, VT, N1, NegOne);
AddToWorklist(Add.getNode());
return DAG.getNode(ISD::AND, DL, VT, N0, Add);
}
if (N1.getOpcode() == ISD::SHL &&
DAG.isKnownToBeAPowerOfTwo(N1.getOperand(0))) {
// fold (urem x, (shl pow2, y)) -> (and x, (add (shl pow2, y), -1))
SDValue NegOne = DAG.getAllOnesConstant(DL, VT);
SDValue Add = DAG.getNode(ISD::ADD, DL, VT, N1, NegOne);
AddToWorklist(Add.getNode());
return DAG.getNode(ISD::AND, DL, VT, N0, Add);
}
}
AttributeList Attr = DAG.getMachineFunction().getFunction().getAttributes();
// If X/C can be simplified by the division-by-constant logic, lower
// X%C to the equivalent of X-X/C*C.
// Reuse the SDIVLike/UDIVLike combines - to avoid mangling nodes, the
// speculative DIV must not cause a DIVREM conversion. We guard against this
// by skipping the simplification if isIntDivCheap(). When div is not cheap,
// combine will not return a DIVREM. Regardless, checking cheapness here
// makes sense since the simplification results in fatter code.
if (DAG.isKnownNeverZero(N1) && !TLI.isIntDivCheap(VT, Attr)) {
if (isSigned) {
// check if we can build faster implementation for srem
if (SDValue OptimizedRem = buildOptimizedSREM(N0, N1, N))
return OptimizedRem;
}
SDValue OptimizedDiv =
isSigned ? visitSDIVLike(N0, N1, N) : visitUDIVLike(N0, N1, N);
if (OptimizedDiv.getNode() && OptimizedDiv.getNode() != N) {
// If the equivalent Div node also exists, update its users.
unsigned DivOpcode = isSigned ? ISD::SDIV : ISD::UDIV;
if (SDNode *DivNode = DAG.getNodeIfExists(DivOpcode, N->getVTList(),
{ N0, N1 }))
CombineTo(DivNode, OptimizedDiv);
SDValue Mul = DAG.getNode(ISD::MUL, DL, VT, OptimizedDiv, N1);
SDValue Sub = DAG.getNode(ISD::SUB, DL, VT, N0, Mul);
AddToWorklist(OptimizedDiv.getNode());
AddToWorklist(Mul.getNode());
return Sub;
}
}
// sdiv, srem -> sdivrem
if (SDValue DivRem = useDivRem(N))
return DivRem.getValue(1);
return SDValue();
}
SDValue DAGCombiner::visitMULHS(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
SDLoc DL(N);
// fold (mulhs c1, c2)
if (SDValue C = DAG.FoldConstantArithmetic(ISD::MULHS, DL, VT, {N0, N1}))
return C;
// canonicalize constant to RHS.
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(ISD::MULHS, DL, N->getVTList(), N1, N0);
if (VT.isVector()) {
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
// fold (mulhs x, 0) -> 0
// do not return N1, because undef node may exist.
if (ISD::isConstantSplatVectorAllZeros(N1.getNode()))
return DAG.getConstant(0, DL, VT);
}
// fold (mulhs x, 0) -> 0
if (isNullConstant(N1))
return N1;
// fold (mulhs x, 1) -> (sra x, size(x)-1)
if (isOneConstant(N1))
return DAG.getNode(ISD::SRA, DL, N0.getValueType(), N0,
DAG.getConstant(N0.getScalarValueSizeInBits() - 1, DL,
getShiftAmountTy(N0.getValueType())));
// fold (mulhs x, undef) -> 0
if (N0.isUndef() || N1.isUndef())
return DAG.getConstant(0, DL, VT);
// If the type twice as wide is legal, transform the mulhs to a wider multiply
// plus a shift.
if (!TLI.isOperationLegalOrCustom(ISD::MULHS, VT) && VT.isSimple() &&
!VT.isVector()) {
MVT Simple = VT.getSimpleVT();
unsigned SimpleSize = Simple.getSizeInBits();
EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), SimpleSize*2);
if (TLI.isOperationLegal(ISD::MUL, NewVT)) {
N0 = DAG.getNode(ISD::SIGN_EXTEND, DL, NewVT, N0);
N1 = DAG.getNode(ISD::SIGN_EXTEND, DL, NewVT, N1);
N1 = DAG.getNode(ISD::MUL, DL, NewVT, N0, N1);
N1 = DAG.getNode(ISD::SRL, DL, NewVT, N1,
DAG.getConstant(SimpleSize, DL,
getShiftAmountTy(N1.getValueType())));
return DAG.getNode(ISD::TRUNCATE, DL, VT, N1);
}
}
return SDValue();
}
SDValue DAGCombiner::visitMULHU(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
SDLoc DL(N);
// fold (mulhu c1, c2)
if (SDValue C = DAG.FoldConstantArithmetic(ISD::MULHU, DL, VT, {N0, N1}))
return C;
// canonicalize constant to RHS.
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(ISD::MULHU, DL, N->getVTList(), N1, N0);
if (VT.isVector()) {
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
// fold (mulhu x, 0) -> 0
// do not return N1, because undef node may exist.
if (ISD::isConstantSplatVectorAllZeros(N1.getNode()))
return DAG.getConstant(0, DL, VT);
}
// fold (mulhu x, 0) -> 0
if (isNullConstant(N1))
return N1;
// fold (mulhu x, 1) -> 0
if (isOneConstant(N1))
return DAG.getConstant(0, DL, N0.getValueType());
// fold (mulhu x, undef) -> 0
if (N0.isUndef() || N1.isUndef())
return DAG.getConstant(0, DL, VT);
// fold (mulhu x, (1 << c)) -> x >> (bitwidth - c)
if (isConstantOrConstantVector(N1, /*NoOpaques*/ true) &&
DAG.isKnownToBeAPowerOfTwo(N1) && hasOperation(ISD::SRL, VT)) {
unsigned NumEltBits = VT.getScalarSizeInBits();
SDValue LogBase2 = BuildLogBase2(N1, DL);
SDValue SRLAmt = DAG.getNode(
ISD::SUB, DL, VT, DAG.getConstant(NumEltBits, DL, VT), LogBase2);
EVT ShiftVT = getShiftAmountTy(N0.getValueType());
SDValue Trunc = DAG.getZExtOrTrunc(SRLAmt, DL, ShiftVT);
return DAG.getNode(ISD::SRL, DL, VT, N0, Trunc);
}
// If the type twice as wide is legal, transform the mulhu to a wider multiply
// plus a shift.
if (!TLI.isOperationLegalOrCustom(ISD::MULHU, VT) && VT.isSimple() &&
!VT.isVector()) {
MVT Simple = VT.getSimpleVT();
unsigned SimpleSize = Simple.getSizeInBits();
EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), SimpleSize*2);
if (TLI.isOperationLegal(ISD::MUL, NewVT)) {
N0 = DAG.getNode(ISD::ZERO_EXTEND, DL, NewVT, N0);
N1 = DAG.getNode(ISD::ZERO_EXTEND, DL, NewVT, N1);
N1 = DAG.getNode(ISD::MUL, DL, NewVT, N0, N1);
N1 = DAG.getNode(ISD::SRL, DL, NewVT, N1,
DAG.getConstant(SimpleSize, DL,
getShiftAmountTy(N1.getValueType())));
return DAG.getNode(ISD::TRUNCATE, DL, VT, N1);
}
}
// Simplify the operands using demanded-bits information.
// We don't have demanded bits support for MULHU so this just enables constant
// folding based on known bits.
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
return SDValue();
}
SDValue DAGCombiner::visitAVG(SDNode *N) {
unsigned Opcode = N->getOpcode();
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
SDLoc DL(N);
// fold (avg c1, c2)
if (SDValue C = DAG.FoldConstantArithmetic(Opcode, DL, VT, {N0, N1}))
return C;
// canonicalize constant to RHS.
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(Opcode, DL, N->getVTList(), N1, N0);
if (VT.isVector()) {
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
// fold (avgfloor x, 0) -> x >> 1
if (ISD::isConstantSplatVectorAllZeros(N1.getNode())) {
if (Opcode == ISD::AVGFLOORS)
return DAG.getNode(ISD::SRA, DL, VT, N0, DAG.getConstant(1, DL, VT));
if (Opcode == ISD::AVGFLOORU)
return DAG.getNode(ISD::SRL, DL, VT, N0, DAG.getConstant(1, DL, VT));
}
}
// fold (avg x, undef) -> x
if (N0.isUndef())
return N1;
if (N1.isUndef())
return N0;
// TODO If we use avg for scalars anywhere, we can add (avgfl x, 0) -> x >> 1
return SDValue();
}
/// Perform optimizations common to nodes that compute two values. LoOp and HiOp
/// give the opcodes for the two computations that are being performed. Return
/// true if a simplification was made.
SDValue DAGCombiner::SimplifyNodeWithTwoResults(SDNode *N, unsigned LoOp,
unsigned HiOp) {
// If the high half is not needed, just compute the low half.
bool HiExists = N->hasAnyUseOfValue(1);
if (!HiExists && (!LegalOperations ||
TLI.isOperationLegalOrCustom(LoOp, N->getValueType(0)))) {
SDValue Res = DAG.getNode(LoOp, SDLoc(N), N->getValueType(0), N->ops());
return CombineTo(N, Res, Res);
}
// If the low half is not needed, just compute the high half.
bool LoExists = N->hasAnyUseOfValue(0);
if (!LoExists && (!LegalOperations ||
TLI.isOperationLegalOrCustom(HiOp, N->getValueType(1)))) {
SDValue Res = DAG.getNode(HiOp, SDLoc(N), N->getValueType(1), N->ops());
return CombineTo(N, Res, Res);
}
// If both halves are used, return as it is.
if (LoExists && HiExists)
return SDValue();
// If the two computed results can be simplified separately, separate them.
if (LoExists) {
SDValue Lo = DAG.getNode(LoOp, SDLoc(N), N->getValueType(0), N->ops());
AddToWorklist(Lo.getNode());
SDValue LoOpt = combine(Lo.getNode());
if (LoOpt.getNode() && LoOpt.getNode() != Lo.getNode() &&
(!LegalOperations ||
TLI.isOperationLegalOrCustom(LoOpt.getOpcode(), LoOpt.getValueType())))
return CombineTo(N, LoOpt, LoOpt);
}
if (HiExists) {
SDValue Hi = DAG.getNode(HiOp, SDLoc(N), N->getValueType(1), N->ops());
AddToWorklist(Hi.getNode());
SDValue HiOpt = combine(Hi.getNode());
if (HiOpt.getNode() && HiOpt != Hi &&
(!LegalOperations ||
TLI.isOperationLegalOrCustom(HiOpt.getOpcode(), HiOpt.getValueType())))
return CombineTo(N, HiOpt, HiOpt);
}
return SDValue();
}
SDValue DAGCombiner::visitSMUL_LOHI(SDNode *N) {
if (SDValue Res = SimplifyNodeWithTwoResults(N, ISD::MUL, ISD::MULHS))
return Res;
EVT VT = N->getValueType(0);
SDLoc DL(N);
// If the type is twice as wide is legal, transform the mulhu to a wider
// multiply plus a shift.
if (VT.isSimple() && !VT.isVector()) {
MVT Simple = VT.getSimpleVT();
unsigned SimpleSize = Simple.getSizeInBits();
EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), SimpleSize*2);
if (TLI.isOperationLegal(ISD::MUL, NewVT)) {
SDValue Lo = DAG.getNode(ISD::SIGN_EXTEND, DL, NewVT, N->getOperand(0));
SDValue Hi = DAG.getNode(ISD::SIGN_EXTEND, DL, NewVT, N->getOperand(1));
Lo = DAG.getNode(ISD::MUL, DL, NewVT, Lo, Hi);
// Compute the high part as N1.
Hi = DAG.getNode(ISD::SRL, DL, NewVT, Lo,
DAG.getConstant(SimpleSize, DL,
getShiftAmountTy(Lo.getValueType())));
Hi = DAG.getNode(ISD::TRUNCATE, DL, VT, Hi);
// Compute the low part as N0.
Lo = DAG.getNode(ISD::TRUNCATE, DL, VT, Lo);
return CombineTo(N, Lo, Hi);
}
}
return SDValue();
}
SDValue DAGCombiner::visitUMUL_LOHI(SDNode *N) {
if (SDValue Res = SimplifyNodeWithTwoResults(N, ISD::MUL, ISD::MULHU))
return Res;
EVT VT = N->getValueType(0);
SDLoc DL(N);
// (umul_lohi N0, 0) -> (0, 0)
if (isNullConstant(N->getOperand(1))) {
SDValue Zero = DAG.getConstant(0, DL, VT);
return CombineTo(N, Zero, Zero);
}
// (umul_lohi N0, 1) -> (N0, 0)
if (isOneConstant(N->getOperand(1))) {
SDValue Zero = DAG.getConstant(0, DL, VT);
return CombineTo(N, N->getOperand(0), Zero);
}
// If the type is twice as wide is legal, transform the mulhu to a wider
// multiply plus a shift.
if (VT.isSimple() && !VT.isVector()) {
MVT Simple = VT.getSimpleVT();
unsigned SimpleSize = Simple.getSizeInBits();
EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), SimpleSize*2);
if (TLI.isOperationLegal(ISD::MUL, NewVT)) {
SDValue Lo = DAG.getNode(ISD::ZERO_EXTEND, DL, NewVT, N->getOperand(0));
SDValue Hi = DAG.getNode(ISD::ZERO_EXTEND, DL, NewVT, N->getOperand(1));
Lo = DAG.getNode(ISD::MUL, DL, NewVT, Lo, Hi);
// Compute the high part as N1.
Hi = DAG.getNode(ISD::SRL, DL, NewVT, Lo,
DAG.getConstant(SimpleSize, DL,
getShiftAmountTy(Lo.getValueType())));
Hi = DAG.getNode(ISD::TRUNCATE, DL, VT, Hi);
// Compute the low part as N0.
Lo = DAG.getNode(ISD::TRUNCATE, DL, VT, Lo);
return CombineTo(N, Lo, Hi);
}
}
return SDValue();
}
SDValue DAGCombiner::visitMULO(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
bool IsSigned = (ISD::SMULO == N->getOpcode());
EVT CarryVT = N->getValueType(1);
SDLoc DL(N);
ConstantSDNode *N0C = isConstOrConstSplat(N0);
ConstantSDNode *N1C = isConstOrConstSplat(N1);
// fold operation with constant operands.
// TODO: Move this to FoldConstantArithmetic when it supports nodes with
// multiple results.
if (N0C && N1C) {
bool Overflow;
APInt Result =
IsSigned ? N0C->getAPIntValue().smul_ov(N1C->getAPIntValue(), Overflow)
: N0C->getAPIntValue().umul_ov(N1C->getAPIntValue(), Overflow);
return CombineTo(N, DAG.getConstant(Result, DL, VT),
DAG.getBoolConstant(Overflow, DL, CarryVT, CarryVT));
}
// canonicalize constant to RHS.
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(N->getOpcode(), DL, N->getVTList(), N1, N0);
// fold (mulo x, 0) -> 0 + no carry out
if (isNullOrNullSplat(N1))
return CombineTo(N, DAG.getConstant(0, DL, VT),
DAG.getConstant(0, DL, CarryVT));
// (mulo x, 2) -> (addo x, x)
// FIXME: This needs a freeze.
if (N1C && N1C->getAPIntValue() == 2 &&
(!IsSigned || VT.getScalarSizeInBits() > 2))
return DAG.getNode(IsSigned ? ISD::SADDO : ISD::UADDO, DL,
N->getVTList(), N0, N0);
if (IsSigned) {
// A 1 bit SMULO overflows if both inputs are 1.
if (VT.getScalarSizeInBits() == 1) {
SDValue And = DAG.getNode(ISD::AND, DL, VT, N0, N1);
return CombineTo(N, And,
DAG.getSetCC(DL, CarryVT, And,
DAG.getConstant(0, DL, VT), ISD::SETNE));
}
// Multiplying n * m significant bits yields a result of n + m significant
// bits. If the total number of significant bits does not exceed the
// result bit width (minus 1), there is no overflow.
unsigned SignBits = DAG.ComputeNumSignBits(N0);
if (SignBits > 1)
SignBits += DAG.ComputeNumSignBits(N1);
if (SignBits > VT.getScalarSizeInBits() + 1)
return CombineTo(N, DAG.getNode(ISD::MUL, DL, VT, N0, N1),
DAG.getConstant(0, DL, CarryVT));
} else {
KnownBits N1Known = DAG.computeKnownBits(N1);
KnownBits N0Known = DAG.computeKnownBits(N0);
bool Overflow;
(void)N0Known.getMaxValue().umul_ov(N1Known.getMaxValue(), Overflow);
if (!Overflow)
return CombineTo(N, DAG.getNode(ISD::MUL, DL, VT, N0, N1),
DAG.getConstant(0, DL, CarryVT));
}
return SDValue();
}
// Function to calculate whether the Min/Max pair of SDNodes (potentially
// swapped around) make a signed saturate pattern, clamping to between a signed
// saturate of -2^(BW-1) and 2^(BW-1)-1, or an unsigned saturate of 0 and 2^BW.
// Returns the node being clamped and the bitwidth of the clamp in BW. Should
// work with both SMIN/SMAX nodes and setcc/select combo. The operands are the
// same as SimplifySelectCC. N0<N1 ? N2 : N3.
static SDValue isSaturatingMinMax(SDValue N0, SDValue N1, SDValue N2,
SDValue N3, ISD::CondCode CC, unsigned &BW,
bool &Unsigned) {
auto isSignedMinMax = [&](SDValue N0, SDValue N1, SDValue N2, SDValue N3,
ISD::CondCode CC) {
// The compare and select operand should be the same or the select operands
// should be truncated versions of the comparison.
if (N0 != N2 && (N2.getOpcode() != ISD::TRUNCATE || N0 != N2.getOperand(0)))
return 0;
// The constants need to be the same or a truncated version of each other.
ConstantSDNode *N1C = isConstOrConstSplat(N1);
ConstantSDNode *N3C = isConstOrConstSplat(N3);
if (!N1C || !N3C)
return 0;
const APInt &C1 = N1C->getAPIntValue();
const APInt &C2 = N3C->getAPIntValue();
if (C1.getBitWidth() < C2.getBitWidth() || C1 != C2.sext(C1.getBitWidth()))
return 0;
return CC == ISD::SETLT ? ISD::SMIN : (CC == ISD::SETGT ? ISD::SMAX : 0);
};
// Check the initial value is a SMIN/SMAX equivalent.
unsigned Opcode0 = isSignedMinMax(N0, N1, N2, N3, CC);
if (!Opcode0)
return SDValue();
SDValue N00, N01, N02, N03;
ISD::CondCode N0CC;
switch (N0.getOpcode()) {
case ISD::SMIN:
case ISD::SMAX:
N00 = N02 = N0.getOperand(0);
N01 = N03 = N0.getOperand(1);
N0CC = N0.getOpcode() == ISD::SMIN ? ISD::SETLT : ISD::SETGT;
break;
case ISD::SELECT_CC:
N00 = N0.getOperand(0);
N01 = N0.getOperand(1);
N02 = N0.getOperand(2);
N03 = N0.getOperand(3);
N0CC = cast<CondCodeSDNode>(N0.getOperand(4))->get();
break;
case ISD::SELECT:
case ISD::VSELECT:
if (N0.getOperand(0).getOpcode() != ISD::SETCC)
return SDValue();
N00 = N0.getOperand(0).getOperand(0);
N01 = N0.getOperand(0).getOperand(1);
N02 = N0.getOperand(1);
N03 = N0.getOperand(2);
N0CC = cast<CondCodeSDNode>(N0.getOperand(0).getOperand(2))->get();
break;
default:
return SDValue();
}
unsigned Opcode1 = isSignedMinMax(N00, N01, N02, N03, N0CC);
if (!Opcode1 || Opcode0 == Opcode1)
return SDValue();
ConstantSDNode *MinCOp = isConstOrConstSplat(Opcode0 == ISD::SMIN ? N1 : N01);
ConstantSDNode *MaxCOp = isConstOrConstSplat(Opcode0 == ISD::SMIN ? N01 : N1);
if (!MinCOp || !MaxCOp || MinCOp->getValueType(0) != MaxCOp->getValueType(0))
return SDValue();
const APInt &MinC = MinCOp->getAPIntValue();
const APInt &MaxC = MaxCOp->getAPIntValue();
APInt MinCPlus1 = MinC + 1;
if (-MaxC == MinCPlus1 && MinCPlus1.isPowerOf2()) {
BW = MinCPlus1.exactLogBase2() + 1;
Unsigned = false;
return N02;
}
if (MaxC == 0 && MinCPlus1.isPowerOf2()) {
BW = MinCPlus1.exactLogBase2();
Unsigned = true;
return N02;
}
return SDValue();
}
static SDValue PerformMinMaxFpToSatCombine(SDValue N0, SDValue N1, SDValue N2,
SDValue N3, ISD::CondCode CC,
SelectionDAG &DAG) {
unsigned BW;
bool Unsigned;
SDValue Fp = isSaturatingMinMax(N0, N1, N2, N3, CC, BW, Unsigned);
if (!Fp || Fp.getOpcode() != ISD::FP_TO_SINT)
return SDValue();
EVT FPVT = Fp.getOperand(0).getValueType();
EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), BW);
if (FPVT.isVector())
NewVT = EVT::getVectorVT(*DAG.getContext(), NewVT,
FPVT.getVectorElementCount());
unsigned NewOpc = Unsigned ? ISD::FP_TO_UINT_SAT : ISD::FP_TO_SINT_SAT;
if (!DAG.getTargetLoweringInfo().shouldConvertFpToSat(NewOpc, FPVT, NewVT))
return SDValue();
SDLoc DL(Fp);
SDValue Sat = DAG.getNode(NewOpc, DL, NewVT, Fp.getOperand(0),
DAG.getValueType(NewVT.getScalarType()));
return Unsigned ? DAG.getZExtOrTrunc(Sat, DL, N2->getValueType(0))
: DAG.getSExtOrTrunc(Sat, DL, N2->getValueType(0));
}
static SDValue PerformUMinFpToSatCombine(SDValue N0, SDValue N1, SDValue N2,
SDValue N3, ISD::CondCode CC,
SelectionDAG &DAG) {
// We are looking for UMIN(FPTOUI(X), (2^n)-1), which may have come via a
// select/vselect/select_cc. The two operands pairs for the select (N2/N3) may
// be truncated versions of the the setcc (N0/N1).
if ((N0 != N2 &&
(N2.getOpcode() != ISD::TRUNCATE || N0 != N2.getOperand(0))) ||
N0.getOpcode() != ISD::FP_TO_UINT || CC != ISD::SETULT)
return SDValue();
ConstantSDNode *N1C = isConstOrConstSplat(N1);
ConstantSDNode *N3C = isConstOrConstSplat(N3);
if (!N1C || !N3C)
return SDValue();
const APInt &C1 = N1C->getAPIntValue();
const APInt &C3 = N3C->getAPIntValue();
if (!(C1 + 1).isPowerOf2() || C1.getBitWidth() < C3.getBitWidth() ||
C1 != C3.zext(C1.getBitWidth()))
return SDValue();
unsigned BW = (C1 + 1).exactLogBase2();
EVT FPVT = N0.getOperand(0).getValueType();
EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), BW);
if (FPVT.isVector())
NewVT = EVT::getVectorVT(*DAG.getContext(), NewVT,
FPVT.getVectorElementCount());
if (!DAG.getTargetLoweringInfo().shouldConvertFpToSat(ISD::FP_TO_UINT_SAT,
FPVT, NewVT))
return SDValue();
SDValue Sat =
DAG.getNode(ISD::FP_TO_UINT_SAT, SDLoc(N0), NewVT, N0.getOperand(0),
DAG.getValueType(NewVT.getScalarType()));
return DAG.getZExtOrTrunc(Sat, SDLoc(N0), N3.getValueType());
}
SDValue DAGCombiner::visitIMINMAX(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
unsigned Opcode = N->getOpcode();
SDLoc DL(N);
// fold operation with constant operands.
if (SDValue C = DAG.FoldConstantArithmetic(Opcode, DL, VT, {N0, N1}))
return C;
// If the operands are the same, this is a no-op.
if (N0 == N1)
return N0;
// canonicalize constant to RHS
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(Opcode, DL, VT, N1, N0);
// fold vector ops
if (VT.isVector())
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
// Is sign bits are zero, flip between UMIN/UMAX and SMIN/SMAX.
// Only do this if the current op isn't legal and the flipped is.
if (!TLI.isOperationLegal(Opcode, VT) &&
(N0.isUndef() || DAG.SignBitIsZero(N0)) &&
(N1.isUndef() || DAG.SignBitIsZero(N1))) {
unsigned AltOpcode;
switch (Opcode) {
case ISD::SMIN: AltOpcode = ISD::UMIN; break;
case ISD::SMAX: AltOpcode = ISD::UMAX; break;
case ISD::UMIN: AltOpcode = ISD::SMIN; break;
case ISD::UMAX: AltOpcode = ISD::SMAX; break;
default: llvm_unreachable("Unknown MINMAX opcode");
}
if (TLI.isOperationLegal(AltOpcode, VT))
return DAG.getNode(AltOpcode, DL, VT, N0, N1);
}
if (Opcode == ISD::SMIN || Opcode == ISD::SMAX)
if (SDValue S = PerformMinMaxFpToSatCombine(
N0, N1, N0, N1, Opcode == ISD::SMIN ? ISD::SETLT : ISD::SETGT, DAG))
return S;
if (Opcode == ISD::UMIN)
if (SDValue S = PerformUMinFpToSatCombine(N0, N1, N0, N1, ISD::SETULT, DAG))
return S;
// Simplify the operands using demanded-bits information.
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
return SDValue();
}
/// If this is a bitwise logic instruction and both operands have the same
/// opcode, try to sink the other opcode after the logic instruction.
SDValue DAGCombiner::hoistLogicOpWithSameOpcodeHands(SDNode *N) {
SDValue N0 = N->getOperand(0), N1 = N->getOperand(1);
EVT VT = N0.getValueType();
unsigned LogicOpcode = N->getOpcode();
unsigned HandOpcode = N0.getOpcode();
assert((LogicOpcode == ISD::AND || LogicOpcode == ISD::OR ||
LogicOpcode == ISD::XOR) && "Expected logic opcode");
assert(HandOpcode == N1.getOpcode() && "Bad input!");
// Bail early if none of these transforms apply.
if (N0.getNumOperands() == 0)
return SDValue();
// FIXME: We should check number of uses of the operands to not increase
// the instruction count for all transforms.
// Handle size-changing casts.
SDValue X = N0.getOperand(0);
SDValue Y = N1.getOperand(0);
EVT XVT = X.getValueType();
SDLoc DL(N);
if (HandOpcode == ISD::ANY_EXTEND || HandOpcode == ISD::ZERO_EXTEND ||
HandOpcode == ISD::SIGN_EXTEND) {
// If both operands have other uses, this transform would create extra
// instructions without eliminating anything.
if (!N0.hasOneUse() && !N1.hasOneUse())
return SDValue();
// We need matching integer source types.
if (XVT != Y.getValueType())
return SDValue();
// Don't create an illegal op during or after legalization. Don't ever
// create an unsupported vector op.
if ((VT.isVector() || LegalOperations) &&
!TLI.isOperationLegalOrCustom(LogicOpcode, XVT))
return SDValue();
// Avoid infinite looping with PromoteIntBinOp.
// TODO: Should we apply desirable/legal constraints to all opcodes?
if (HandOpcode == ISD::ANY_EXTEND && LegalTypes &&
!TLI.isTypeDesirableForOp(LogicOpcode, XVT))
return SDValue();
// logic_op (hand_op X), (hand_op Y) --> hand_op (logic_op X, Y)
SDValue Logic = DAG.getNode(LogicOpcode, DL, XVT, X, Y);
return DAG.getNode(HandOpcode, DL, VT, Logic);
}
// logic_op (truncate x), (truncate y) --> truncate (logic_op x, y)
if (HandOpcode == ISD::TRUNCATE) {
// If both operands have other uses, this transform would create extra
// instructions without eliminating anything.
if (!N0.hasOneUse() && !N1.hasOneUse())
return SDValue();
// We need matching source types.
if (XVT != Y.getValueType())
return SDValue();
// Don't create an illegal op during or after legalization.
if (LegalOperations && !TLI.isOperationLegal(LogicOpcode, XVT))
return SDValue();
// Be extra careful sinking truncate. If it's free, there's no benefit in
// widening a binop. Also, don't create a logic op on an illegal type.
if (TLI.isZExtFree(VT, XVT) && TLI.isTruncateFree(XVT, VT))
return SDValue();
if (!TLI.isTypeLegal(XVT))
return SDValue();
SDValue Logic = DAG.getNode(LogicOpcode, DL, XVT, X, Y);
return DAG.getNode(HandOpcode, DL, VT, Logic);
}
// For binops SHL/SRL/SRA/AND:
// logic_op (OP x, z), (OP y, z) --> OP (logic_op x, y), z
if ((HandOpcode == ISD::SHL || HandOpcode == ISD::SRL ||
HandOpcode == ISD::SRA || HandOpcode == ISD::AND) &&
N0.getOperand(1) == N1.getOperand(1)) {
// If either operand has other uses, this transform is not an improvement.
if (!N0.hasOneUse() || !N1.hasOneUse())
return SDValue();
SDValue Logic = DAG.getNode(LogicOpcode, DL, XVT, X, Y);
return DAG.getNode(HandOpcode, DL, VT, Logic, N0.getOperand(1));
}
// Unary ops: logic_op (bswap x), (bswap y) --> bswap (logic_op x, y)
if (HandOpcode == ISD::BSWAP) {
// If either operand has other uses, this transform is not an improvement.
if (!N0.hasOneUse() || !N1.hasOneUse())
return SDValue();
SDValue Logic = DAG.getNode(LogicOpcode, DL, XVT, X, Y);
return DAG.getNode(HandOpcode, DL, VT, Logic);
}
// Simplify xor/and/or (bitcast(A), bitcast(B)) -> bitcast(op (A,B))
// Only perform this optimization up until type legalization, before
// LegalizeVectorOprs. LegalizeVectorOprs promotes vector operations by
// adding bitcasts. For example (xor v4i32) is promoted to (v2i64), and
// we don't want to undo this promotion.
// We also handle SCALAR_TO_VECTOR because xor/or/and operations are cheaper
// on scalars.
if ((HandOpcode == ISD::BITCAST || HandOpcode == ISD::SCALAR_TO_VECTOR) &&
Level <= AfterLegalizeTypes) {
// Input types must be integer and the same.
if (XVT.isInteger() && XVT == Y.getValueType() &&
!(VT.isVector() && TLI.isTypeLegal(VT) &&
!XVT.isVector() && !TLI.isTypeLegal(XVT))) {
SDValue Logic = DAG.getNode(LogicOpcode, DL, XVT, X, Y);
return DAG.getNode(HandOpcode, DL, VT, Logic);
}
}
// Xor/and/or are indifferent to the swizzle operation (shuffle of one value).
// Simplify xor/and/or (shuff(A), shuff(B)) -> shuff(op (A,B))
// If both shuffles use the same mask, and both shuffle within a single
// vector, then it is worthwhile to move the swizzle after the operation.
// The type-legalizer generates this pattern when loading illegal
// vector types from memory. In many cases this allows additional shuffle
// optimizations.
// There are other cases where moving the shuffle after the xor/and/or
// is profitable even if shuffles don't perform a swizzle.
// If both shuffles use the same mask, and both shuffles have the same first
// or second operand, then it might still be profitable to move the shuffle
// after the xor/and/or operation.
if (HandOpcode == ISD::VECTOR_SHUFFLE && Level < AfterLegalizeDAG) {
auto *SVN0 = cast<ShuffleVectorSDNode>(N0);
auto *SVN1 = cast<ShuffleVectorSDNode>(N1);
assert(X.getValueType() == Y.getValueType() &&
"Inputs to shuffles are not the same type");
// Check that both shuffles use the same mask. The masks are known to be of
// the same length because the result vector type is the same.
// Check also that shuffles have only one use to avoid introducing extra
// instructions.
if (!SVN0->hasOneUse() || !SVN1->hasOneUse() ||
!SVN0->getMask().equals(SVN1->getMask()))
return SDValue();
// Don't try to fold this node if it requires introducing a
// build vector of all zeros that might be illegal at this stage.
SDValue ShOp = N0.getOperand(1);
if (LogicOpcode == ISD::XOR && !ShOp.isUndef())
ShOp = tryFoldToZero(DL, TLI, VT, DAG, LegalOperations);
// (logic_op (shuf (A, C), shuf (B, C))) --> shuf (logic_op (A, B), C)
if (N0.getOperand(1) == N1.getOperand(1) && ShOp.getNode()) {
SDValue Logic = DAG.getNode(LogicOpcode, DL, VT,
N0.getOperand(0), N1.getOperand(0));
return DAG.getVectorShuffle(VT, DL, Logic, ShOp, SVN0->getMask());
}
// Don't try to fold this node if it requires introducing a
// build vector of all zeros that might be illegal at this stage.
ShOp = N0.getOperand(0);
if (LogicOpcode == ISD::XOR && !ShOp.isUndef())
ShOp = tryFoldToZero(DL, TLI, VT, DAG, LegalOperations);
// (logic_op (shuf (C, A), shuf (C, B))) --> shuf (C, logic_op (A, B))
if (N0.getOperand(0) == N1.getOperand(0) && ShOp.getNode()) {
SDValue Logic = DAG.getNode(LogicOpcode, DL, VT, N0.getOperand(1),
N1.getOperand(1));
return DAG.getVectorShuffle(VT, DL, ShOp, Logic, SVN0->getMask());
}
}
return SDValue();
}
/// Try to make (and/or setcc (LL, LR), setcc (RL, RR)) more efficient.
SDValue DAGCombiner::foldLogicOfSetCCs(bool IsAnd, SDValue N0, SDValue N1,
const SDLoc &DL) {
SDValue LL, LR, RL, RR, N0CC, N1CC;
if (!isSetCCEquivalent(N0, LL, LR, N0CC) ||
!isSetCCEquivalent(N1, RL, RR, N1CC))
return SDValue();
assert(N0.getValueType() == N1.getValueType() &&
"Unexpected operand types for bitwise logic op");
assert(LL.getValueType() == LR.getValueType() &&
RL.getValueType() == RR.getValueType() &&
"Unexpected operand types for setcc");
// If we're here post-legalization or the logic op type is not i1, the logic
// op type must match a setcc result type. Also, all folds require new
// operations on the left and right operands, so those types must match.
EVT VT = N0.getValueType();
EVT OpVT = LL.getValueType();
if (LegalOperations || VT.getScalarType() != MVT::i1)
if (VT != getSetCCResultType(OpVT))
return SDValue();
if (OpVT != RL.getValueType())
return SDValue();
ISD::CondCode CC0 = cast<CondCodeSDNode>(N0CC)->get();
ISD::CondCode CC1 = cast<CondCodeSDNode>(N1CC)->get();
bool IsInteger = OpVT.isInteger();
if (LR == RR && CC0 == CC1 && IsInteger) {
bool IsZero = isNullOrNullSplat(LR);
bool IsNeg1 = isAllOnesOrAllOnesSplat(LR);
// All bits clear?
bool AndEqZero = IsAnd && CC1 == ISD::SETEQ && IsZero;
// All sign bits clear?
bool AndGtNeg1 = IsAnd && CC1 == ISD::SETGT && IsNeg1;
// Any bits set?
bool OrNeZero = !IsAnd && CC1 == ISD::SETNE && IsZero;
// Any sign bits set?
bool OrLtZero = !IsAnd && CC1 == ISD::SETLT && IsZero;
// (and (seteq X, 0), (seteq Y, 0)) --> (seteq (or X, Y), 0)
// (and (setgt X, -1), (setgt Y, -1)) --> (setgt (or X, Y), -1)
// (or (setne X, 0), (setne Y, 0)) --> (setne (or X, Y), 0)
// (or (setlt X, 0), (setlt Y, 0)) --> (setlt (or X, Y), 0)
if (AndEqZero || AndGtNeg1 || OrNeZero || OrLtZero) {
SDValue Or = DAG.getNode(ISD::OR, SDLoc(N0), OpVT, LL, RL);
AddToWorklist(Or.getNode());
return DAG.getSetCC(DL, VT, Or, LR, CC1);
}
// All bits set?
bool AndEqNeg1 = IsAnd && CC1 == ISD::SETEQ && IsNeg1;
// All sign bits set?
bool AndLtZero = IsAnd && CC1 == ISD::SETLT && IsZero;
// Any bits clear?
bool OrNeNeg1 = !IsAnd && CC1 == ISD::SETNE && IsNeg1;
// Any sign bits clear?
bool OrGtNeg1 = !IsAnd && CC1 == ISD::SETGT && IsNeg1;
// (and (seteq X, -1), (seteq Y, -1)) --> (seteq (and X, Y), -1)
// (and (setlt X, 0), (setlt Y, 0)) --> (setlt (and X, Y), 0)
// (or (setne X, -1), (setne Y, -1)) --> (setne (and X, Y), -1)
// (or (setgt X, -1), (setgt Y -1)) --> (setgt (and X, Y), -1)
if (AndEqNeg1 || AndLtZero || OrNeNeg1 || OrGtNeg1) {
SDValue And = DAG.getNode(ISD::AND, SDLoc(N0), OpVT, LL, RL);
AddToWorklist(And.getNode());
return DAG.getSetCC(DL, VT, And, LR, CC1);
}
}
// TODO: What is the 'or' equivalent of this fold?
// (and (setne X, 0), (setne X, -1)) --> (setuge (add X, 1), 2)
if (IsAnd && LL == RL && CC0 == CC1 && OpVT.getScalarSizeInBits() > 1 &&
IsInteger && CC0 == ISD::SETNE &&
((isNullConstant(LR) && isAllOnesConstant(RR)) ||
(isAllOnesConstant(LR) && isNullConstant(RR)))) {
SDValue One = DAG.getConstant(1, DL, OpVT);
SDValue Two = DAG.getConstant(2, DL, OpVT);
SDValue Add = DAG.getNode(ISD::ADD, SDLoc(N0), OpVT, LL, One);
AddToWorklist(Add.getNode());
return DAG.getSetCC(DL, VT, Add, Two, ISD::SETUGE);
}
// Try more general transforms if the predicates match and the only user of
// the compares is the 'and' or 'or'.
if (IsInteger && TLI.convertSetCCLogicToBitwiseLogic(OpVT) && CC0 == CC1 &&
N0.hasOneUse() && N1.hasOneUse()) {
// and (seteq A, B), (seteq C, D) --> seteq (or (xor A, B), (xor C, D)), 0
// or (setne A, B), (setne C, D) --> setne (or (xor A, B), (xor C, D)), 0
if ((IsAnd && CC1 == ISD::SETEQ) || (!IsAnd && CC1 == ISD::SETNE)) {
SDValue XorL = DAG.getNode(ISD::XOR, SDLoc(N0), OpVT, LL, LR);
SDValue XorR = DAG.getNode(ISD::XOR, SDLoc(N1), OpVT, RL, RR);
SDValue Or = DAG.getNode(ISD::OR, DL, OpVT, XorL, XorR);
SDValue Zero = DAG.getConstant(0, DL, OpVT);
return DAG.getSetCC(DL, VT, Or, Zero, CC1);
}
// Turn compare of constants whose difference is 1 bit into add+and+setcc.
if ((IsAnd && CC1 == ISD::SETNE) || (!IsAnd && CC1 == ISD::SETEQ)) {
// Match a shared variable operand and 2 non-opaque constant operands.
auto MatchDiffPow2 = [&](ConstantSDNode *C0, ConstantSDNode *C1) {
// The difference of the constants must be a single bit.
const APInt &CMax =
APIntOps::umax(C0->getAPIntValue(), C1->getAPIntValue());
const APInt &CMin =
APIntOps::umin(C0->getAPIntValue(), C1->getAPIntValue());
return !C0->isOpaque() && !C1->isOpaque() && (CMax - CMin).isPowerOf2();
};
if (LL == RL && ISD::matchBinaryPredicate(LR, RR, MatchDiffPow2)) {
// and/or (setcc X, CMax, ne), (setcc X, CMin, ne/eq) -->
// setcc ((sub X, CMin), ~(CMax - CMin)), 0, ne/eq
SDValue Max = DAG.getNode(ISD::UMAX, DL, OpVT, LR, RR);
SDValue Min = DAG.getNode(ISD::UMIN, DL, OpVT, LR, RR);
SDValue Offset = DAG.getNode(ISD::SUB, DL, OpVT, LL, Min);
SDValue Diff = DAG.getNode(ISD::SUB, DL, OpVT, Max, Min);
SDValue Mask = DAG.getNOT(DL, Diff, OpVT);
SDValue And = DAG.getNode(ISD::AND, DL, OpVT, Offset, Mask);
SDValue Zero = DAG.getConstant(0, DL, OpVT);
return DAG.getSetCC(DL, VT, And, Zero, CC0);
}
}
}
// Canonicalize equivalent operands to LL == RL.
if (LL == RR && LR == RL) {
CC1 = ISD::getSetCCSwappedOperands(CC1);
std::swap(RL, RR);
}
// (and (setcc X, Y, CC0), (setcc X, Y, CC1)) --> (setcc X, Y, NewCC)
// (or (setcc X, Y, CC0), (setcc X, Y, CC1)) --> (setcc X, Y, NewCC)
if (LL == RL && LR == RR) {
ISD::CondCode NewCC = IsAnd ? ISD::getSetCCAndOperation(CC0, CC1, OpVT)
: ISD::getSetCCOrOperation(CC0, CC1, OpVT);
if (NewCC != ISD::SETCC_INVALID &&
(!LegalOperations ||
(TLI.isCondCodeLegal(NewCC, LL.getSimpleValueType()) &&
TLI.isOperationLegal(ISD::SETCC, OpVT))))
return DAG.getSetCC(DL, VT, LL, LR, NewCC);
}
return SDValue();
}
/// This contains all DAGCombine rules which reduce two values combined by
/// an And operation to a single value. This makes them reusable in the context
/// of visitSELECT(). Rules involving constants are not included as
/// visitSELECT() already handles those cases.
SDValue DAGCombiner::visitANDLike(SDValue N0, SDValue N1, SDNode *N) {
EVT VT = N1.getValueType();
SDLoc DL(N);
// fold (and x, undef) -> 0
if (N0.isUndef() || N1.isUndef())
return DAG.getConstant(0, DL, VT);
if (SDValue V = foldLogicOfSetCCs(true, N0, N1, DL))
return V;
// TODO: Rewrite this to return a new 'AND' instead of using CombineTo.
if (N0.getOpcode() == ISD::ADD && N1.getOpcode() == ISD::SRL &&
VT.getSizeInBits() <= 64 && N0->hasOneUse()) {
if (ConstantSDNode *ADDI = dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
if (ConstantSDNode *SRLI = dyn_cast<ConstantSDNode>(N1.getOperand(1))) {
// Look for (and (add x, c1), (lshr y, c2)). If C1 wasn't a legal
// immediate for an add, but it is legal if its top c2 bits are set,
// transform the ADD so the immediate doesn't need to be materialized
// in a register.
APInt ADDC = ADDI->getAPIntValue();
APInt SRLC = SRLI->getAPIntValue();
if (ADDC.getMinSignedBits() <= 64 &&
SRLC.ult(VT.getSizeInBits()) &&
!TLI.isLegalAddImmediate(ADDC.getSExtValue())) {
APInt Mask = APInt::getHighBitsSet(VT.getSizeInBits(),
SRLC.getZExtValue());
if (DAG.MaskedValueIsZero(N0.getOperand(1), Mask)) {
ADDC |= Mask;
if (TLI.isLegalAddImmediate(ADDC.getSExtValue())) {
SDLoc DL0(N0);
SDValue NewAdd =
DAG.getNode(ISD::ADD, DL0, VT,
N0.getOperand(0), DAG.getConstant(ADDC, DL, VT));
CombineTo(N0.getNode(), NewAdd);
// Return N so it doesn't get rechecked!
return SDValue(N, 0);
}
}
}
}
}
}
// Reduce bit extract of low half of an integer to the narrower type.
// (and (srl i64:x, K), KMask) ->
// (i64 zero_extend (and (srl (i32 (trunc i64:x)), K)), KMask)
if (N0.getOpcode() == ISD::SRL && N0.hasOneUse()) {
if (ConstantSDNode *CAnd = dyn_cast<ConstantSDNode>(N1)) {
if (ConstantSDNode *CShift = dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
unsigned Size = VT.getSizeInBits();
const APInt &AndMask = CAnd->getAPIntValue();
unsigned ShiftBits = CShift->getZExtValue();
// Bail out, this node will probably disappear anyway.
if (ShiftBits == 0)
return SDValue();
unsigned MaskBits = AndMask.countTrailingOnes();
EVT HalfVT = EVT::getIntegerVT(*DAG.getContext(), Size / 2);
if (AndMask.isMask() &&
// Required bits must not span the two halves of the integer and
// must fit in the half size type.
(ShiftBits + MaskBits <= Size / 2) &&
TLI.isNarrowingProfitable(VT, HalfVT) &&
TLI.isTypeDesirableForOp(ISD::AND, HalfVT) &&
TLI.isTypeDesirableForOp(ISD::SRL, HalfVT) &&
TLI.isTruncateFree(VT, HalfVT) &&
TLI.isZExtFree(HalfVT, VT)) {
// The isNarrowingProfitable is to avoid regressions on PPC and
// AArch64 which match a few 64-bit bit insert / bit extract patterns
// on downstream users of this. Those patterns could probably be
// extended to handle extensions mixed in.
SDValue SL(N0);
assert(MaskBits <= Size);
// Extracting the highest bit of the low half.
EVT ShiftVT = TLI.getShiftAmountTy(HalfVT, DAG.getDataLayout());
SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SL, HalfVT,
N0.getOperand(0));
SDValue NewMask = DAG.getConstant(AndMask.trunc(Size / 2), SL, HalfVT);
SDValue ShiftK = DAG.getConstant(ShiftBits, SL, ShiftVT);
SDValue Shift = DAG.getNode(ISD::SRL, SL, HalfVT, Trunc, ShiftK);
SDValue And = DAG.getNode(ISD::AND, SL, HalfVT, Shift, NewMask);
return DAG.getNode(ISD::ZERO_EXTEND, SL, VT, And);
}
}
}
}
return SDValue();
}
bool DAGCombiner::isAndLoadExtLoad(ConstantSDNode *AndC, LoadSDNode *LoadN,
EVT LoadResultTy, EVT &ExtVT) {
if (!AndC->getAPIntValue().isMask())
return false;
unsigned ActiveBits = AndC->getAPIntValue().countTrailingOnes();
ExtVT = EVT::getIntegerVT(*DAG.getContext(), ActiveBits);
EVT LoadedVT = LoadN->getMemoryVT();
if (ExtVT == LoadedVT &&
(!LegalOperations ||
TLI.isLoadExtLegal(ISD::ZEXTLOAD, LoadResultTy, ExtVT))) {
// ZEXTLOAD will match without needing to change the size of the value being
// loaded.
return true;
}
// Do not change the width of a volatile or atomic loads.
if (!LoadN->isSimple())
return false;
// Do not generate loads of non-round integer types since these can
// be expensive (and would be wrong if the type is not byte sized).
if (!LoadedVT.bitsGT(ExtVT) || !ExtVT.isRound())
return false;
if (LegalOperations &&
!TLI.isLoadExtLegal(ISD::ZEXTLOAD, LoadResultTy, ExtVT))
return false;
if (!TLI.shouldReduceLoadWidth(LoadN, ISD::ZEXTLOAD, ExtVT))
return false;
return true;
}
bool DAGCombiner::isLegalNarrowLdSt(LSBaseSDNode *LDST,
ISD::LoadExtType ExtType, EVT &MemVT,
unsigned ShAmt) {
if (!LDST)
return false;
// Only allow byte offsets.
if (ShAmt % 8)
return false;
// Do not generate loads of non-round integer types since these can
// be expensive (and would be wrong if the type is not byte sized).
if (!MemVT.isRound())
return false;
// Don't change the width of a volatile or atomic loads.
if (!LDST->isSimple())
return false;
EVT LdStMemVT = LDST->getMemoryVT();
// Bail out when changing the scalable property, since we can't be sure that
// we're actually narrowing here.
if (LdStMemVT.isScalableVector() != MemVT.isScalableVector())
return false;
// Verify that we are actually reducing a load width here.
if (LdStMemVT.bitsLT(MemVT))
return false;
// Ensure that this isn't going to produce an unsupported memory access.
if (ShAmt) {
assert(ShAmt % 8 == 0 && "ShAmt is byte offset");
const unsigned ByteShAmt = ShAmt / 8;
const Align LDSTAlign = LDST->getAlign();
const Align NarrowAlign = commonAlignment(LDSTAlign, ByteShAmt);
if (!TLI.allowsMemoryAccess(*DAG.getContext(), DAG.getDataLayout(), MemVT,
LDST->getAddressSpace(), NarrowAlign,
LDST->getMemOperand()->getFlags()))
return false;
}
// It's not possible to generate a constant of extended or untyped type.
EVT PtrType = LDST->getBasePtr().getValueType();
if (PtrType == MVT::Untyped || PtrType.isExtended())
return false;
if (isa<LoadSDNode>(LDST)) {
LoadSDNode *Load = cast<LoadSDNode>(LDST);
// Don't transform one with multiple uses, this would require adding a new
// load.
if (!SDValue(Load, 0).hasOneUse())
return false;
if (LegalOperations &&
!TLI.isLoadExtLegal(ExtType, Load->getValueType(0), MemVT))
return false;
// For the transform to be legal, the load must produce only two values
// (the value loaded and the chain). Don't transform a pre-increment
// load, for example, which produces an extra value. Otherwise the
// transformation is not equivalent, and the downstream logic to replace
// uses gets things wrong.
if (Load->getNumValues() > 2)
return false;
// If the load that we're shrinking is an extload and we're not just
// discarding the extension we can't simply shrink the load. Bail.
// TODO: It would be possible to merge the extensions in some cases.
if (Load->getExtensionType() != ISD::NON_EXTLOAD &&
Load->getMemoryVT().getSizeInBits() < MemVT.getSizeInBits() + ShAmt)
return false;
if (!TLI.shouldReduceLoadWidth(Load, ExtType, MemVT))
return false;
} else {
assert(isa<StoreSDNode>(LDST) && "It is not a Load nor a Store SDNode");
StoreSDNode *Store = cast<StoreSDNode>(LDST);
// Can't write outside the original store
if (Store->getMemoryVT().getSizeInBits() < MemVT.getSizeInBits() + ShAmt)
return false;
if (LegalOperations &&
!TLI.isTruncStoreLegal(Store->getValue().getValueType(), MemVT))
return false;
}
return true;
}
bool DAGCombiner::SearchForAndLoads(SDNode *N,
SmallVectorImpl<LoadSDNode*> &Loads,
SmallPtrSetImpl<SDNode*> &NodesWithConsts,
ConstantSDNode *Mask,
SDNode *&NodeToMask) {
// Recursively search for the operands, looking for loads which can be
// narrowed.
for (SDValue Op : N->op_values()) {
if (Op.getValueType().isVector())
return false;
// Some constants may need fixing up later if they are too large.
if (auto *C = dyn_cast<ConstantSDNode>(Op)) {
if ((N->getOpcode() == ISD::OR || N->getOpcode() == ISD::XOR) &&
(Mask->getAPIntValue() & C->getAPIntValue()) != C->getAPIntValue())
NodesWithConsts.insert(N);
continue;
}
if (!Op.hasOneUse())
return false;
switch(Op.getOpcode()) {
case ISD::LOAD: {
auto *Load = cast<LoadSDNode>(Op);
EVT ExtVT;
if (isAndLoadExtLoad(Mask, Load, Load->getValueType(0), ExtVT) &&
isLegalNarrowLdSt(Load, ISD::ZEXTLOAD, ExtVT)) {
// ZEXTLOAD is already small enough.
if (Load->getExtensionType() == ISD::ZEXTLOAD &&
ExtVT.bitsGE(Load->getMemoryVT()))
continue;
// Use LE to convert equal sized loads to zext.
if (ExtVT.bitsLE(Load->getMemoryVT()))
Loads.push_back(Load);
continue;
}
return false;
}
case ISD::ZERO_EXTEND:
case ISD::AssertZext: {
unsigned ActiveBits = Mask->getAPIntValue().countTrailingOnes();
EVT ExtVT = EVT::getIntegerVT(*DAG.getContext(), ActiveBits);
EVT VT = Op.getOpcode() == ISD::AssertZext ?
cast<VTSDNode>(Op.getOperand(1))->getVT() :
Op.getOperand(0).getValueType();
// We can accept extending nodes if the mask is wider or an equal
// width to the original type.
if (ExtVT.bitsGE(VT))
continue;
break;
}
case ISD::OR:
case ISD::XOR:
case ISD::AND:
if (!SearchForAndLoads(Op.getNode(), Loads, NodesWithConsts, Mask,
NodeToMask))
return false;
continue;
}
// Allow one node which will masked along with any loads found.
if (NodeToMask)
return false;
// Also ensure that the node to be masked only produces one data result.
NodeToMask = Op.getNode();
if (NodeToMask->getNumValues() > 1) {
bool HasValue = false;
for (unsigned i = 0, e = NodeToMask->getNumValues(); i < e; ++i) {
MVT VT = SDValue(NodeToMask, i).getSimpleValueType();
if (VT != MVT::Glue && VT != MVT::Other) {
if (HasValue) {
NodeToMask = nullptr;
return false;
}
HasValue = true;
}
}
assert(HasValue && "Node to be masked has no data result?");
}
}
return true;
}
bool DAGCombiner::BackwardsPropagateMask(SDNode *N) {
auto *Mask = dyn_cast<ConstantSDNode>(N->getOperand(1));
if (!Mask)
return false;
if (!Mask->getAPIntValue().isMask())
return false;
// No need to do anything if the and directly uses a load.
if (isa<LoadSDNode>(N->getOperand(0)))
return false;
SmallVector<LoadSDNode*, 8> Loads;
SmallPtrSet<SDNode*, 2> NodesWithConsts;
SDNode *FixupNode = nullptr;
if (SearchForAndLoads(N, Loads, NodesWithConsts, Mask, FixupNode)) {
if (Loads.size() == 0)
return false;
LLVM_DEBUG(dbgs() << "Backwards propagate AND: "; N->dump());
SDValue MaskOp = N->getOperand(1);
// If it exists, fixup the single node we allow in the tree that needs
// masking.
if (FixupNode) {
LLVM_DEBUG(dbgs() << "First, need to fix up: "; FixupNode->dump());
SDValue And = DAG.getNode(ISD::AND, SDLoc(FixupNode),
FixupNode->getValueType(0),
SDValue(FixupNode, 0), MaskOp);
DAG.ReplaceAllUsesOfValueWith(SDValue(FixupNode, 0), And);
if (And.getOpcode() == ISD ::AND)
DAG.UpdateNodeOperands(And.getNode(), SDValue(FixupNode, 0), MaskOp);
}
// Narrow any constants that need it.
for (auto *LogicN : NodesWithConsts) {
SDValue Op0 = LogicN->getOperand(0);
SDValue Op1 = LogicN->getOperand(1);
if (isa<ConstantSDNode>(Op0))
std::swap(Op0, Op1);
SDValue And = DAG.getNode(ISD::AND, SDLoc(Op1), Op1.getValueType(),
Op1, MaskOp);
DAG.UpdateNodeOperands(LogicN, Op0, And);
}
// Create narrow loads.
for (auto *Load : Loads) {
LLVM_DEBUG(dbgs() << "Propagate AND back to: "; Load->dump());
SDValue And = DAG.getNode(ISD::AND, SDLoc(Load), Load->getValueType(0),
SDValue(Load, 0), MaskOp);
DAG.ReplaceAllUsesOfValueWith(SDValue(Load, 0), And);
if (And.getOpcode() == ISD ::AND)
And = SDValue(
DAG.UpdateNodeOperands(And.getNode(), SDValue(Load, 0), MaskOp), 0);
SDValue NewLoad = reduceLoadWidth(And.getNode());
assert(NewLoad &&
"Shouldn't be masking the load if it can't be narrowed");
CombineTo(Load, NewLoad, NewLoad.getValue(1));
}
DAG.ReplaceAllUsesWith(N, N->getOperand(0).getNode());
return true;
}
return false;
}
// Unfold
// x & (-1 'logical shift' y)
// To
// (x 'opposite logical shift' y) 'logical shift' y
// if it is better for performance.
SDValue DAGCombiner::unfoldExtremeBitClearingToShifts(SDNode *N) {
assert(N->getOpcode() == ISD::AND);
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
// Do we actually prefer shifts over mask?
if (!TLI.shouldFoldMaskToVariableShiftPair(N0))
return SDValue();
// Try to match (-1 '[outer] logical shift' y)
unsigned OuterShift;
unsigned InnerShift; // The opposite direction to the OuterShift.
SDValue Y; // Shift amount.
auto matchMask = [&OuterShift, &InnerShift, &Y](SDValue M) -> bool {
if (!M.hasOneUse())
return false;
OuterShift = M->getOpcode();
if (OuterShift == ISD::SHL)
InnerShift = ISD::SRL;
else if (OuterShift == ISD::SRL)
InnerShift = ISD::SHL;
else
return false;
if (!isAllOnesConstant(M->getOperand(0)))
return false;
Y = M->getOperand(1);
return true;
};
SDValue X;
if (matchMask(N1))
X = N0;
else if (matchMask(N0))
X = N1;
else
return SDValue();
SDLoc DL(N);
EVT VT = N->getValueType(0);
// tmp = x 'opposite logical shift' y
SDValue T0 = DAG.getNode(InnerShift, DL, VT, X, Y);
// ret = tmp 'logical shift' y
SDValue T1 = DAG.getNode(OuterShift, DL, VT, T0, Y);
return T1;
}
/// Try to replace shift/logic that tests if a bit is clear with mask + setcc.
/// For a target with a bit test, this is expected to become test + set and save
/// at least 1 instruction.
static SDValue combineShiftAnd1ToBitTest(SDNode *And, SelectionDAG &DAG) {
assert(And->getOpcode() == ISD::AND && "Expected an 'and' op");
// This is probably not worthwhile without a supported type.
EVT VT = And->getValueType(0);
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
if (!TLI.isTypeLegal(VT))
return SDValue();
// Look through an optional extension and find a 'not'.
// TODO: Should we favor test+set even without the 'not' op?
SDValue Not = And->getOperand(0), And1 = And->getOperand(1);
if (Not.getOpcode() == ISD::ANY_EXTEND)
Not = Not.getOperand(0);
if (!isBitwiseNot(Not) || !Not.hasOneUse() || !isOneConstant(And1))
return SDValue();
// Look though an optional truncation. The source operand may not be the same
// type as the original 'and', but that is ok because we are masking off
// everything but the low bit.
SDValue Srl = Not.getOperand(0);
if (Srl.getOpcode() == ISD::TRUNCATE)
Srl = Srl.getOperand(0);
// Match a shift-right by constant.
if (Srl.getOpcode() != ISD::SRL || !Srl.hasOneUse() ||
!isa<ConstantSDNode>(Srl.getOperand(1)))
return SDValue();
// We might have looked through casts that make this transform invalid.
// TODO: If the source type is wider than the result type, do the mask and
// compare in the source type.
const APInt &ShiftAmt = Srl.getConstantOperandAPInt(1);
unsigned VTBitWidth = VT.getSizeInBits();
if (ShiftAmt.uge(VTBitWidth))
return SDValue();
if (!TLI.hasBitTest(Srl.getOperand(0), Srl.getOperand(1)))
return SDValue();
// Turn this into a bit-test pattern using mask op + setcc:
// and (not (srl X, C)), 1 --> (and X, 1<<C) == 0
SDLoc DL(And);
SDValue X = DAG.getZExtOrTrunc(Srl.getOperand(0), DL, VT);
EVT CCVT = TLI.getSetCCResultType(DAG.getDataLayout(), *DAG.getContext(), VT);
SDValue Mask = DAG.getConstant(
APInt::getOneBitSet(VTBitWidth, ShiftAmt.getZExtValue()), DL, VT);
SDValue NewAnd = DAG.getNode(ISD::AND, DL, VT, X, Mask);
SDValue Zero = DAG.getConstant(0, DL, VT);
SDValue Setcc = DAG.getSetCC(DL, CCVT, NewAnd, Zero, ISD::SETEQ);
return DAG.getZExtOrTrunc(Setcc, DL, VT);
}
/// For targets that support usubsat, match a bit-hack form of that operation
/// that ends in 'and' and convert it.
static SDValue foldAndToUsubsat(SDNode *N, SelectionDAG &DAG) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N1.getValueType();
// Canonicalize SRA as operand 1.
if (N0.getOpcode() == ISD::SRA)
std::swap(N0, N1);
// xor/add with SMIN (signmask) are logically equivalent.
if (N0.getOpcode() != ISD::XOR && N0.getOpcode() != ISD::ADD)
return SDValue();
if (N1.getOpcode() != ISD::SRA || !N0.hasOneUse() || !N1.hasOneUse() ||
N0.getOperand(0) != N1.getOperand(0))
return SDValue();
unsigned BitWidth = VT.getScalarSizeInBits();
ConstantSDNode *XorC = isConstOrConstSplat(N0.getOperand(1), true);
ConstantSDNode *SraC = isConstOrConstSplat(N1.getOperand(1), true);
if (!XorC || !XorC->getAPIntValue().isSignMask() ||
!SraC || SraC->getAPIntValue() != BitWidth - 1)
return SDValue();
// (i8 X ^ 128) & (i8 X s>> 7) --> usubsat X, 128
// (i8 X + 128) & (i8 X s>> 7) --> usubsat X, 128
SDLoc DL(N);
SDValue SignMask = DAG.getConstant(XorC->getAPIntValue(), DL, VT);
return DAG.getNode(ISD::USUBSAT, DL, VT, N0.getOperand(0), SignMask);
}
/// Given a bitwise logic operation N with a matching bitwise logic operand,
/// fold a pattern where 2 of the source operands are identically shifted
/// values. For example:
/// ((X0 << Y) | Z) | (X1 << Y) --> ((X0 | X1) << Y) | Z
static SDValue foldLogicOfShifts(SDNode *N, SDValue LogicOp, SDValue ShiftOp,
SelectionDAG &DAG) {
unsigned LogicOpcode = N->getOpcode();
assert((LogicOpcode == ISD::AND || LogicOpcode == ISD::OR ||
LogicOpcode == ISD::XOR)
&& "Expected bitwise logic operation");
if (!LogicOp.hasOneUse() || !ShiftOp.hasOneUse())
return SDValue();
// Match another bitwise logic op and a shift.
unsigned ShiftOpcode = ShiftOp.getOpcode();
if (LogicOp.getOpcode() != LogicOpcode ||
!(ShiftOpcode == ISD::SHL || ShiftOpcode == ISD::SRL ||
ShiftOpcode == ISD::SRA))
return SDValue();
// Match another shift op inside the first logic operand. Handle both commuted
// possibilities.
// LOGIC (LOGIC (SH X0, Y), Z), (SH X1, Y) --> LOGIC (SH (LOGIC X0, X1), Y), Z
// LOGIC (LOGIC Z, (SH X0, Y)), (SH X1, Y) --> LOGIC (SH (LOGIC X0, X1), Y), Z
SDValue X1 = ShiftOp.getOperand(0);
SDValue Y = ShiftOp.getOperand(1);
SDValue X0, Z;
if (LogicOp.getOperand(0).getOpcode() == ShiftOpcode &&
LogicOp.getOperand(0).getOperand(1) == Y) {
X0 = LogicOp.getOperand(0).getOperand(0);
Z = LogicOp.getOperand(1);
} else if (LogicOp.getOperand(1).getOpcode() == ShiftOpcode &&
LogicOp.getOperand(1).getOperand(1) == Y) {
X0 = LogicOp.getOperand(1).getOperand(0);
Z = LogicOp.getOperand(0);
} else {
return SDValue();
}
EVT VT = N->getValueType(0);
SDLoc DL(N);
SDValue LogicX = DAG.getNode(LogicOpcode, DL, VT, X0, X1);
SDValue NewShift = DAG.getNode(ShiftOpcode, DL, VT, LogicX, Y);
return DAG.getNode(LogicOpcode, DL, VT, NewShift, Z);
}
SDValue DAGCombiner::visitAND(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N1.getValueType();
// x & x --> x
if (N0 == N1)
return N0;
// fold (and c1, c2) -> c1&c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::AND, SDLoc(N), VT, {N0, N1}))
return C;
// canonicalize constant to RHS
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(ISD::AND, SDLoc(N), VT, N1, N0);
// fold vector ops
if (VT.isVector()) {
if (SDValue FoldedVOp = SimplifyVBinOp(N, SDLoc(N)))
return FoldedVOp;
// fold (and x, 0) -> 0, vector edition
if (ISD::isConstantSplatVectorAllZeros(N1.getNode()))
// do not return N1, because undef node may exist in N1
return DAG.getConstant(APInt::getZero(N1.getScalarValueSizeInBits()),
SDLoc(N), N1.getValueType());
// fold (and x, -1) -> x, vector edition
if (ISD::isConstantSplatVectorAllOnes(N1.getNode()))
return N0;
// fold (and (masked_load) (splat_vec (x, ...))) to zext_masked_load
auto *MLoad = dyn_cast<MaskedLoadSDNode>(N0);
ConstantSDNode *Splat = isConstOrConstSplat(N1, true, true);
if (MLoad && MLoad->getExtensionType() == ISD::EXTLOAD && N0.hasOneUse() &&
Splat && N1.hasOneUse()) {
EVT LoadVT = MLoad->getMemoryVT();
EVT ExtVT = VT;
if (TLI.isLoadExtLegal(ISD::ZEXTLOAD, ExtVT, LoadVT)) {
// For this AND to be a zero extension of the masked load the elements
// of the BuildVec must mask the bottom bits of the extended element
// type
uint64_t ElementSize =
LoadVT.getVectorElementType().getScalarSizeInBits();
if (Splat->getAPIntValue().isMask(ElementSize)) {
return DAG.getMaskedLoad(
ExtVT, SDLoc(N), MLoad->getChain(), MLoad->getBasePtr(),
MLoad->getOffset(), MLoad->getMask(), MLoad->getPassThru(),
LoadVT, MLoad->getMemOperand(), MLoad->getAddressingMode(),
ISD::ZEXTLOAD, MLoad->isExpandingLoad());
}
}
}
}
// fold (and x, -1) -> x
if (isAllOnesConstant(N1))
return N0;
// if (and x, c) is known to be zero, return 0
unsigned BitWidth = VT.getScalarSizeInBits();
ConstantSDNode *N1C = isConstOrConstSplat(N1);
if (N1C && DAG.MaskedValueIsZero(SDValue(N, 0), APInt::getAllOnes(BitWidth)))
return DAG.getConstant(0, SDLoc(N), VT);
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
// reassociate and
if (SDValue RAND = reassociateOps(ISD::AND, SDLoc(N), N0, N1, N->getFlags()))
return RAND;
// Try to convert a constant mask AND into a shuffle clear mask.
if (VT.isVector())
if (SDValue Shuffle = XformToShuffleWithZero(N))
return Shuffle;
if (SDValue Combined = combineCarryDiamond(DAG, TLI, N0, N1, N))
return Combined;
// fold (and (or x, C), D) -> D if (C & D) == D
auto MatchSubset = [](ConstantSDNode *LHS, ConstantSDNode *RHS) {
return RHS->getAPIntValue().isSubsetOf(LHS->getAPIntValue());
};
if (N0.getOpcode() == ISD::OR &&
ISD::matchBinaryPredicate(N0.getOperand(1), N1, MatchSubset))
return N1;
// fold (and (any_ext V), c) -> (zero_ext V) if 'and' only clears top bits.
if (N1C && N0.getOpcode() == ISD::ANY_EXTEND) {
SDValue N0Op0 = N0.getOperand(0);
APInt Mask = ~N1C->getAPIntValue();
Mask = Mask.trunc(N0Op0.getScalarValueSizeInBits());
if (DAG.MaskedValueIsZero(N0Op0, Mask)) {
SDValue Zext = DAG.getNode(ISD::ZERO_EXTEND, SDLoc(N),
N0.getValueType(), N0Op0);
// Replace uses of the AND with uses of the Zero extend node.
CombineTo(N, Zext);
// We actually want to replace all uses of the any_extend with the
// zero_extend, to avoid duplicating things. This will later cause this
// AND to be folded.
CombineTo(N0.getNode(), Zext);
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
}
// similarly fold (and (X (load ([non_ext|any_ext|zero_ext] V))), c) ->
// (X (load ([non_ext|zero_ext] V))) if 'and' only clears top bits which must
// already be zero by virtue of the width of the base type of the load.
//
// the 'X' node here can either be nothing or an extract_vector_elt to catch
// more cases.
if ((N0.getOpcode() == ISD::EXTRACT_VECTOR_ELT &&
N0.getValueSizeInBits() == N0.getOperand(0).getScalarValueSizeInBits() &&
N0.getOperand(0).getOpcode() == ISD::LOAD &&
N0.getOperand(0).getResNo() == 0) ||
(N0.getOpcode() == ISD::LOAD && N0.getResNo() == 0)) {
LoadSDNode *Load = cast<LoadSDNode>( (N0.getOpcode() == ISD::LOAD) ?
N0 : N0.getOperand(0) );
// Get the constant (if applicable) the zero'th operand is being ANDed with.
// This can be a pure constant or a vector splat, in which case we treat the
// vector as a scalar and use the splat value.
APInt Constant = APInt::getZero(1);
if (const ConstantSDNode *C = isConstOrConstSplat(N1)) {
Constant = C->getAPIntValue();
} else if (BuildVectorSDNode *Vector = dyn_cast<BuildVectorSDNode>(N1)) {
APInt SplatValue, SplatUndef;
unsigned SplatBitSize;
bool HasAnyUndefs;
bool IsSplat = Vector->isConstantSplat(SplatValue, SplatUndef,
SplatBitSize, HasAnyUndefs);
if (IsSplat) {
// Undef bits can contribute to a possible optimisation if set, so
// set them.
SplatValue |= SplatUndef;
// The splat value may be something like "0x00FFFFFF", which means 0 for
// the first vector value and FF for the rest, repeating. We need a mask
// that will apply equally to all members of the vector, so AND all the
// lanes of the constant together.
unsigned EltBitWidth = Vector->getValueType(0).getScalarSizeInBits();
// If the splat value has been compressed to a bitlength lower
// than the size of the vector lane, we need to re-expand it to
// the lane size.
if (EltBitWidth > SplatBitSize)
for (SplatValue = SplatValue.zextOrTrunc(EltBitWidth);
SplatBitSize < EltBitWidth; SplatBitSize = SplatBitSize * 2)
SplatValue |= SplatValue.shl(SplatBitSize);
// Make sure that variable 'Constant' is only set if 'SplatBitSize' is a
// multiple of 'BitWidth'. Otherwise, we could propagate a wrong value.
if ((SplatBitSize % EltBitWidth) == 0) {
Constant = APInt::getAllOnes(EltBitWidth);
for (unsigned i = 0, n = (SplatBitSize / EltBitWidth); i < n; ++i)
Constant &= SplatValue.extractBits(EltBitWidth, i * EltBitWidth);
}
}
}
// If we want to change an EXTLOAD to a ZEXTLOAD, ensure a ZEXTLOAD is
// actually legal and isn't going to get expanded, else this is a false
// optimisation.
bool CanZextLoadProfitably = TLI.isLoadExtLegal(ISD::ZEXTLOAD,
Load->getValueType(0),
Load->getMemoryVT());
// Resize the constant to the same size as the original memory access before
// extension. If it is still the AllOnesValue then this AND is completely
// unneeded.
Constant = Constant.zextOrTrunc(Load->getMemoryVT().getScalarSizeInBits());
bool B;
switch (Load->getExtensionType()) {
default: B = false; break;
case ISD::EXTLOAD: B = CanZextLoadProfitably; break;
case ISD::ZEXTLOAD:
case ISD::NON_EXTLOAD: B = true; break;
}
if (B && Constant.isAllOnes()) {
// If the load type was an EXTLOAD, convert to ZEXTLOAD in order to
// preserve semantics once we get rid of the AND.
SDValue NewLoad(Load, 0);
// Fold the AND away. NewLoad may get replaced immediately.
CombineTo(N, (N0.getNode() == Load) ? NewLoad : N0);
if (Load->getExtensionType() == ISD::EXTLOAD) {
NewLoad = DAG.getLoad(Load->getAddressingMode(), ISD::ZEXTLOAD,
Load->getValueType(0), SDLoc(Load),
Load->getChain(), Load->getBasePtr(),
Load->getOffset(), Load->getMemoryVT(),
Load->getMemOperand());
// Replace uses of the EXTLOAD with the new ZEXTLOAD.
if (Load->getNumValues() == 3) {
// PRE/POST_INC loads have 3 values.
SDValue To[] = { NewLoad.getValue(0), NewLoad.getValue(1),
NewLoad.getValue(2) };
CombineTo(Load, To, 3, true);
} else {
CombineTo(Load, NewLoad.getValue(0), NewLoad.getValue(1));
}
}
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
}
// fold (and (masked_gather x)) -> (zext_masked_gather x)
if (auto *GN0 = dyn_cast<MaskedGatherSDNode>(N0)) {
EVT MemVT = GN0->getMemoryVT();
EVT ScalarVT = MemVT.getScalarType();
if (SDValue(GN0, 0).hasOneUse() &&
isConstantSplatVectorMaskForType(N1.getNode(), ScalarVT) &&
TLI.isVectorLoadExtDesirable(SDValue(SDValue(GN0, 0)))) {
SDValue Ops[] = {GN0->getChain(), GN0->getPassThru(), GN0->getMask(),
GN0->getBasePtr(), GN0->getIndex(), GN0->getScale()};
SDValue ZExtLoad = DAG.getMaskedGather(
DAG.getVTList(VT, MVT::Other), MemVT, SDLoc(N), Ops,
GN0->getMemOperand(), GN0->getIndexType(), ISD::ZEXTLOAD);
CombineTo(N, ZExtLoad);
AddToWorklist(ZExtLoad.getNode());
// Avoid recheck of N.
return SDValue(N, 0);
}
}
// fold (and (load x), 255) -> (zextload x, i8)
// fold (and (extload x, i16), 255) -> (zextload x, i8)
// fold (and (any_ext (extload x, i16)), 255) -> (zextload x, i8)
if (!VT.isVector() && N1C && (N0.getOpcode() == ISD::LOAD ||
(N0.getOpcode() == ISD::ANY_EXTEND &&
N0.getOperand(0).getOpcode() == ISD::LOAD))) {
if (SDValue Res = reduceLoadWidth(N)) {
LoadSDNode *LN0 = N0->getOpcode() == ISD::ANY_EXTEND
? cast<LoadSDNode>(N0.getOperand(0)) : cast<LoadSDNode>(N0);
AddToWorklist(N);
DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 0), Res);
return SDValue(N, 0);
}
}
if (LegalTypes) {
// Attempt to propagate the AND back up to the leaves which, if they're
// loads, can be combined to narrow loads and the AND node can be removed.
// Perform after legalization so that extend nodes will already be
// combined into the loads.
if (BackwardsPropagateMask(N))
return SDValue(N, 0);
}
if (SDValue Combined = visitANDLike(N0, N1, N))
return Combined;
// Simplify: (and (op x...), (op y...)) -> (op (and x, y))
if (N0.getOpcode() == N1.getOpcode())
if (SDValue V = hoistLogicOpWithSameOpcodeHands(N))
return V;
if (SDValue R = foldLogicOfShifts(N, N0, N1, DAG))
return R;
if (SDValue R = foldLogicOfShifts(N, N1, N0, DAG))
return R;
// Masking the negated extension of a boolean is just the zero-extended
// boolean:
// and (sub 0, zext(bool X)), 1 --> zext(bool X)
// and (sub 0, sext(bool X)), 1 --> zext(bool X)
//
// Note: the SimplifyDemandedBits fold below can make an information-losing
// transform, and then we have no way to find this better fold.
if (N1C && N1C->isOne() && N0.getOpcode() == ISD::SUB) {
if (isNullOrNullSplat(N0.getOperand(0))) {
SDValue SubRHS = N0.getOperand(1);
if (SubRHS.getOpcode() == ISD::ZERO_EXTEND &&
SubRHS.getOperand(0).getScalarValueSizeInBits() == 1)
return SubRHS;
if (SubRHS.getOpcode() == ISD::SIGN_EXTEND &&
SubRHS.getOperand(0).getScalarValueSizeInBits() == 1)
return DAG.getNode(ISD::ZERO_EXTEND, SDLoc(N), VT, SubRHS.getOperand(0));
}
}
// fold (and (sign_extend_inreg x, i16 to i32), 1) -> (and x, 1)
// fold (and (sra)) -> (and (srl)) when possible.
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
// fold (zext_inreg (extload x)) -> (zextload x)
// fold (zext_inreg (sextload x)) -> (zextload x) iff load has one use
if (ISD::isUNINDEXEDLoad(N0.getNode()) &&
(ISD::isEXTLoad(N0.getNode()) ||
(ISD::isSEXTLoad(N0.getNode()) && N0.hasOneUse()))) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
EVT MemVT = LN0->getMemoryVT();
// If we zero all the possible extended bits, then we can turn this into
// a zextload if we are running before legalize or the operation is legal.
unsigned ExtBitSize = N1.getScalarValueSizeInBits();
unsigned MemBitSize = MemVT.getScalarSizeInBits();
APInt ExtBits = APInt::getHighBitsSet(ExtBitSize, ExtBitSize - MemBitSize);
if (DAG.MaskedValueIsZero(N1, ExtBits) &&
((!LegalOperations && LN0->isSimple()) ||
TLI.isLoadExtLegal(ISD::ZEXTLOAD, VT, MemVT))) {
SDValue ExtLoad =
DAG.getExtLoad(ISD::ZEXTLOAD, SDLoc(N0), VT, LN0->getChain(),
LN0->getBasePtr(), MemVT, LN0->getMemOperand());
AddToWorklist(N);
CombineTo(N0.getNode(), ExtLoad, ExtLoad.getValue(1));
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
}
// fold (and (or (srl N, 8), (shl N, 8)), 0xffff) -> (srl (bswap N), const)
if (N1C && N1C->getAPIntValue() == 0xffff && N0.getOpcode() == ISD::OR) {
if (SDValue BSwap = MatchBSwapHWordLow(N0.getNode(), N0.getOperand(0),
N0.getOperand(1), false))
return BSwap;
}
if (SDValue Shifts = unfoldExtremeBitClearingToShifts(N))
return Shifts;
if (SDValue V = combineShiftAnd1ToBitTest(N, DAG))
return V;
// Recognize the following pattern:
//
// AndVT = (and (sign_extend NarrowVT to AndVT) #bitmask)
//
// where bitmask is a mask that clears the upper bits of AndVT. The
// number of bits in bitmask must be a power of two.
auto IsAndZeroExtMask = [](SDValue LHS, SDValue RHS) {
if (LHS->getOpcode() != ISD::SIGN_EXTEND)
return false;
auto *C = dyn_cast<ConstantSDNode>(RHS);
if (!C)
return false;
if (!C->getAPIntValue().isMask(
LHS.getOperand(0).getValueType().getFixedSizeInBits()))
return false;
return true;
};
// Replace (and (sign_extend ...) #bitmask) with (zero_extend ...).
if (IsAndZeroExtMask(N0, N1))
return DAG.getNode(ISD::ZERO_EXTEND, SDLoc(N), VT, N0.getOperand(0));
if (hasOperation(ISD::USUBSAT, VT))
if (SDValue V = foldAndToUsubsat(N, DAG))
return V;
return SDValue();
}
/// Match (a >> 8) | (a << 8) as (bswap a) >> 16.
SDValue DAGCombiner::MatchBSwapHWordLow(SDNode *N, SDValue N0, SDValue N1,
bool DemandHighBits) {
if (!LegalOperations)
return SDValue();
EVT VT = N->getValueType(0);
if (VT != MVT::i64 && VT != MVT::i32 && VT != MVT::i16)
return SDValue();
if (!TLI.isOperationLegalOrCustom(ISD::BSWAP, VT))
return SDValue();
// Recognize (and (shl a, 8), 0xff00), (and (srl a, 8), 0xff)
bool LookPassAnd0 = false;
bool LookPassAnd1 = false;
if (N0.getOpcode() == ISD::AND && N0.getOperand(0).getOpcode() == ISD::SRL)
std::swap(N0, N1);
if (N1.getOpcode() == ISD::AND && N1.getOperand(0).getOpcode() == ISD::SHL)
std::swap(N0, N1);
if (N0.getOpcode() == ISD::AND) {
if (!N0->hasOneUse())
return SDValue();
ConstantSDNode *N01C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
// Also handle 0xffff since the LHS is guaranteed to have zeros there.
// This is needed for X86.
if (!N01C || (N01C->getZExtValue() != 0xFF00 &&
N01C->getZExtValue() != 0xFFFF))
return SDValue();
N0 = N0.getOperand(0);
LookPassAnd0 = true;
}
if (N1.getOpcode() == ISD::AND) {
if (!N1->hasOneUse())
return SDValue();
ConstantSDNode *N11C = dyn_cast<ConstantSDNode>(N1.getOperand(1));
if (!N11C || N11C->getZExtValue() != 0xFF)
return SDValue();
N1 = N1.getOperand(0);
LookPassAnd1 = true;
}
if (N0.getOpcode() == ISD::SRL && N1.getOpcode() == ISD::SHL)
std::swap(N0, N1);
if (N0.getOpcode() != ISD::SHL || N1.getOpcode() != ISD::SRL)
return SDValue();
if (!N0->hasOneUse() || !N1->hasOneUse())
return SDValue();
ConstantSDNode *N01C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
ConstantSDNode *N11C = dyn_cast<ConstantSDNode>(N1.getOperand(1));
if (!N01C || !N11C)
return SDValue();
if (N01C->getZExtValue() != 8 || N11C->getZExtValue() != 8)
return SDValue();
// Look for (shl (and a, 0xff), 8), (srl (and a, 0xff00), 8)
SDValue N00 = N0->getOperand(0);
if (!LookPassAnd0 && N00.getOpcode() == ISD::AND) {
if (!N00->hasOneUse())
return SDValue();
ConstantSDNode *N001C = dyn_cast<ConstantSDNode>(N00.getOperand(1));
if (!N001C || N001C->getZExtValue() != 0xFF)
return SDValue();
N00 = N00.getOperand(0);
LookPassAnd0 = true;
}
SDValue N10 = N1->getOperand(0);
if (!LookPassAnd1 && N10.getOpcode() == ISD::AND) {
if (!N10->hasOneUse())
return SDValue();
ConstantSDNode *N101C = dyn_cast<ConstantSDNode>(N10.getOperand(1));
// Also allow 0xFFFF since the bits will be shifted out. This is needed
// for X86.
if (!N101C || (N101C->getZExtValue() != 0xFF00 &&
N101C->getZExtValue() != 0xFFFF))
return SDValue();
N10 = N10.getOperand(0);
LookPassAnd1 = true;
}
if (N00 != N10)
return SDValue();
// Make sure everything beyond the low halfword gets set to zero since the SRL
// 16 will clear the top bits.
unsigned OpSizeInBits = VT.getSizeInBits();
if (OpSizeInBits > 16) {
// If the left-shift isn't masked out then the only way this is a bswap is
// if all bits beyond the low 8 are 0. In that case the entire pattern
// reduces to a left shift anyway: leave it for other parts of the combiner.
if (DemandHighBits && !LookPassAnd0)
return SDValue();
// However, if the right shift isn't masked out then it might be because
// it's not needed. See if we can spot that too. If the high bits aren't
// demanded, we only need bits 23:16 to be zero. Otherwise, we need all
// upper bits to be zero.
if (!LookPassAnd1) {
unsigned HighBit = DemandHighBits ? OpSizeInBits : 24;
if (!DAG.MaskedValueIsZero(N10,
APInt::getBitsSet(OpSizeInBits, 16, HighBit)))
return SDValue();
}
}
SDValue Res = DAG.getNode(ISD::BSWAP, SDLoc(N), VT, N00);
if (OpSizeInBits > 16) {
SDLoc DL(N);
Res = DAG.getNode(ISD::SRL, DL, VT, Res,
DAG.getConstant(OpSizeInBits - 16, DL,
getShiftAmountTy(VT)));
}
return Res;
}
/// Return true if the specified node is an element that makes up a 32-bit
/// packed halfword byteswap.
/// ((x & 0x000000ff) << 8) |
/// ((x & 0x0000ff00) >> 8) |
/// ((x & 0x00ff0000) << 8) |
/// ((x & 0xff000000) >> 8)
static bool isBSwapHWordElement(SDValue N, MutableArrayRef<SDNode *> Parts) {
if (!N->hasOneUse())
return false;
unsigned Opc = N.getOpcode();
if (Opc != ISD::AND && Opc != ISD::SHL && Opc != ISD::SRL)
return false;
SDValue N0 = N.getOperand(0);
unsigned Opc0 = N0.getOpcode();
if (Opc0 != ISD::AND && Opc0 != ISD::SHL && Opc0 != ISD::SRL)
return false;
ConstantSDNode *N1C = nullptr;
// SHL or SRL: look upstream for AND mask operand
if (Opc == ISD::AND)
N1C = dyn_cast<ConstantSDNode>(N.getOperand(1));
else if (Opc0 == ISD::AND)
N1C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
if (!N1C)
return false;
unsigned MaskByteOffset;
switch (N1C->getZExtValue()) {
default:
return false;
case 0xFF: MaskByteOffset = 0; break;
case 0xFF00: MaskByteOffset = 1; break;
case 0xFFFF:
// In case demanded bits didn't clear the bits that will be shifted out.
// This is needed for X86.
if (Opc == ISD::SRL || (Opc == ISD::AND && Opc0 == ISD::SHL)) {
MaskByteOffset = 1;
break;
}
return false;
case 0xFF0000: MaskByteOffset = 2; break;
case 0xFF000000: MaskByteOffset = 3; break;
}
// Look for (x & 0xff) << 8 as well as ((x << 8) & 0xff00).
if (Opc == ISD::AND) {
if (MaskByteOffset == 0 || MaskByteOffset == 2) {
// (x >> 8) & 0xff
// (x >> 8) & 0xff0000
if (Opc0 != ISD::SRL)
return false;
ConstantSDNode *C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
if (!C || C->getZExtValue() != 8)
return false;
} else {
// (x << 8) & 0xff00
// (x << 8) & 0xff000000
if (Opc0 != ISD::SHL)
return false;
ConstantSDNode *C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
if (!C || C->getZExtValue() != 8)
return false;
}
} else if (Opc == ISD::SHL) {
// (x & 0xff) << 8
// (x & 0xff0000) << 8
if (MaskByteOffset != 0 && MaskByteOffset != 2)
return false;
ConstantSDNode *C = dyn_cast<ConstantSDNode>(N.getOperand(1));
if (!C || C->getZExtValue() != 8)
return false;
} else { // Opc == ISD::SRL
// (x & 0xff00) >> 8
// (x & 0xff000000) >> 8
if (MaskByteOffset != 1 && MaskByteOffset != 3)
return false;
ConstantSDNode *C = dyn_cast<ConstantSDNode>(N.getOperand(1));
if (!C || C->getZExtValue() != 8)
return false;
}
if (Parts[MaskByteOffset])
return false;
Parts[MaskByteOffset] = N0.getOperand(0).getNode();
return true;
}
// Match 2 elements of a packed halfword bswap.
static bool isBSwapHWordPair(SDValue N, MutableArrayRef<SDNode *> Parts) {
if (N.getOpcode() == ISD::OR)
return isBSwapHWordElement(N.getOperand(0), Parts) &&
isBSwapHWordElement(N.getOperand(1), Parts);
if (N.getOpcode() == ISD::SRL && N.getOperand(0).getOpcode() == ISD::BSWAP) {
ConstantSDNode *C = isConstOrConstSplat(N.getOperand(1));
if (!C || C->getAPIntValue() != 16)
return false;
Parts[0] = Parts[1] = N.getOperand(0).getOperand(0).getNode();
return true;
}
return false;
}
// Match this pattern:
// (or (and (shl (A, 8)), 0xff00ff00), (and (srl (A, 8)), 0x00ff00ff))
// And rewrite this to:
// (rotr (bswap A), 16)
static SDValue matchBSwapHWordOrAndAnd(const TargetLowering &TLI,
SelectionDAG &DAG, SDNode *N, SDValue N0,
SDValue N1, EVT VT, EVT ShiftAmountTy) {
assert(N->getOpcode() == ISD::OR && VT == MVT::i32 &&
"MatchBSwapHWordOrAndAnd: expecting i32");
if (!TLI.isOperationLegalOrCustom(ISD::ROTR, VT))
return SDValue();
if (N0.getOpcode() != ISD::AND || N1.getOpcode() != ISD::AND)
return SDValue();
// TODO: this is too restrictive; lifting this restriction requires more tests
if (!N0->hasOneUse() || !N1->hasOneUse())
return SDValue();
ConstantSDNode *Mask0 = isConstOrConstSplat(N0.getOperand(1));
ConstantSDNode *Mask1 = isConstOrConstSplat(N1.getOperand(1));
if (!Mask0 || !Mask1)
return SDValue();
if (Mask0->getAPIntValue() != 0xff00ff00 ||
Mask1->getAPIntValue() != 0x00ff00ff)
return SDValue();
SDValue Shift0 = N0.getOperand(0);
SDValue Shift1 = N1.getOperand(0);
if (Shift0.getOpcode() != ISD::SHL || Shift1.getOpcode() != ISD::SRL)
return SDValue();
ConstantSDNode *ShiftAmt0 = isConstOrConstSplat(Shift0.getOperand(1));
ConstantSDNode *ShiftAmt1 = isConstOrConstSplat(Shift1.getOperand(1));
if (!ShiftAmt0 || !ShiftAmt1)
return SDValue();
if (ShiftAmt0->getAPIntValue() != 8 || ShiftAmt1->getAPIntValue() != 8)
return SDValue();
if (Shift0.getOperand(0) != Shift1.getOperand(0))
return SDValue();
SDLoc DL(N);
SDValue BSwap = DAG.getNode(ISD::BSWAP, DL, VT, Shift0.getOperand(0));
SDValue ShAmt = DAG.getConstant(16, DL, ShiftAmountTy);
return DAG.getNode(ISD::ROTR, DL, VT, BSwap, ShAmt);
}
/// Match a 32-bit packed halfword bswap. That is
/// ((x & 0x000000ff) << 8) |
/// ((x & 0x0000ff00) >> 8) |
/// ((x & 0x00ff0000) << 8) |
/// ((x & 0xff000000) >> 8)
/// => (rotl (bswap x), 16)
SDValue DAGCombiner::MatchBSwapHWord(SDNode *N, SDValue N0, SDValue N1) {
if (!LegalOperations)
return SDValue();
EVT VT = N->getValueType(0);
if (VT != MVT::i32)
return SDValue();
if (!TLI.isOperationLegalOrCustom(ISD::BSWAP, VT))
return SDValue();
if (SDValue BSwap = matchBSwapHWordOrAndAnd(TLI, DAG, N, N0, N1, VT,
getShiftAmountTy(VT)))
return BSwap;
// Try again with commuted operands.
if (SDValue BSwap = matchBSwapHWordOrAndAnd(TLI, DAG, N, N1, N0, VT,
getShiftAmountTy(VT)))
return BSwap;
// Look for either
// (or (bswaphpair), (bswaphpair))
// (or (or (bswaphpair), (and)), (and))
// (or (or (and), (bswaphpair)), (and))
SDNode *Parts[4] = {};
if (isBSwapHWordPair(N0, Parts)) {
// (or (or (and), (and)), (or (and), (and)))
if (!isBSwapHWordPair(N1, Parts))
return SDValue();
} else if (N0.getOpcode() == ISD::OR) {
// (or (or (or (and), (and)), (and)), (and))
if (!isBSwapHWordElement(N1, Parts))
return SDValue();
SDValue N00 = N0.getOperand(0);
SDValue N01 = N0.getOperand(1);
if (!(isBSwapHWordElement(N01, Parts) && isBSwapHWordPair(N00, Parts)) &&
!(isBSwapHWordElement(N00, Parts) && isBSwapHWordPair(N01, Parts)))
return SDValue();
} else {
return SDValue();
}
// Make sure the parts are all coming from the same node.
if (Parts[0] != Parts[1] || Parts[0] != Parts[2] || Parts[0] != Parts[3])
return SDValue();
SDLoc DL(N);
SDValue BSwap = DAG.getNode(ISD::BSWAP, DL, VT,
SDValue(Parts[0], 0));
// Result of the bswap should be rotated by 16. If it's not legal, then
// do (x << 16) | (x >> 16).
SDValue ShAmt = DAG.getConstant(16, DL, getShiftAmountTy(VT));
if (TLI.isOperationLegalOrCustom(ISD::ROTL, VT))
return DAG.getNode(ISD::ROTL, DL, VT, BSwap, ShAmt);
if (TLI.isOperationLegalOrCustom(ISD::ROTR, VT))
return DAG.getNode(ISD::ROTR, DL, VT, BSwap, ShAmt);
return DAG.getNode(ISD::OR, DL, VT,
DAG.getNode(ISD::SHL, DL, VT, BSwap, ShAmt),
DAG.getNode(ISD::SRL, DL, VT, BSwap, ShAmt));
}
/// This contains all DAGCombine rules which reduce two values combined by
/// an Or operation to a single value \see visitANDLike().
SDValue DAGCombiner::visitORLike(SDValue N0, SDValue N1, SDNode *N) {
EVT VT = N1.getValueType();
SDLoc DL(N);
// fold (or x, undef) -> -1
if (!LegalOperations && (N0.isUndef() || N1.isUndef()))
return DAG.getAllOnesConstant(DL, VT);
if (SDValue V = foldLogicOfSetCCs(false, N0, N1, DL))
return V;
// (or (and X, C1), (and Y, C2)) -> (and (or X, Y), C3) if possible.
if (N0.getOpcode() == ISD::AND && N1.getOpcode() == ISD::AND &&
// Don't increase # computations.
(N0->hasOneUse() || N1->hasOneUse())) {
// We can only do this xform if we know that bits from X that are set in C2
// but not in C1 are already zero. Likewise for Y.
if (const ConstantSDNode *N0O1C =
getAsNonOpaqueConstant(N0.getOperand(1))) {
if (const ConstantSDNode *N1O1C =
getAsNonOpaqueConstant(N1.getOperand(1))) {
// We can only do this xform if we know that bits from X that are set in
// C2 but not in C1 are already zero. Likewise for Y.
const APInt &LHSMask = N0O1C->getAPIntValue();
const APInt &RHSMask = N1O1C->getAPIntValue();
if (DAG.MaskedValueIsZero(N0.getOperand(0), RHSMask&~LHSMask) &&
DAG.MaskedValueIsZero(N1.getOperand(0), LHSMask&~RHSMask)) {
SDValue X = DAG.getNode(ISD::OR, SDLoc(N0), VT,
N0.getOperand(0), N1.getOperand(0));
return DAG.getNode(ISD::AND, DL, VT, X,
DAG.getConstant(LHSMask | RHSMask, DL, VT));
}
}
}
}
// (or (and X, M), (and X, N)) -> (and X, (or M, N))
if (N0.getOpcode() == ISD::AND &&
N1.getOpcode() == ISD::AND &&
N0.getOperand(0) == N1.getOperand(0) &&
// Don't increase # computations.
(N0->hasOneUse() || N1->hasOneUse())) {
SDValue X = DAG.getNode(ISD::OR, SDLoc(N0), VT,
N0.getOperand(1), N1.getOperand(1));
return DAG.getNode(ISD::AND, DL, VT, N0.getOperand(0), X);
}
return SDValue();
}
/// OR combines for which the commuted variant will be tried as well.
static SDValue visitORCommutative(
SelectionDAG &DAG, SDValue N0, SDValue N1, SDNode *N) {
EVT VT = N0.getValueType();
if (N0.getOpcode() == ISD::AND) {
// fold (or (and X, (xor Y, -1)), Y) -> (or X, Y)
// TODO: Set AllowUndefs = true.
if (getBitwiseNotOperand(N0.getOperand(1), N0.getOperand(0),
/* AllowUndefs */ false) == N1)
return DAG.getNode(ISD::OR, SDLoc(N), VT, N0.getOperand(0), N1);
// fold (or (and (xor Y, -1), X), Y) -> (or X, Y)
if (getBitwiseNotOperand(N0.getOperand(0), N0.getOperand(1),
/* AllowUndefs */ false) == N1)
return DAG.getNode(ISD::OR, SDLoc(N), VT, N0.getOperand(1), N1);
}
if (SDValue R = foldLogicOfShifts(N, N0, N1, DAG))
return R;
auto peekThroughZext = [](SDValue V) {
if (V->getOpcode() == ISD::ZERO_EXTEND)
return V->getOperand(0);
return V;
};
// (fshl X, ?, Y) | (shl X, Y) --> fshl X, ?, Y
if (N0.getOpcode() == ISD::FSHL && N1.getOpcode() == ISD::SHL &&
N0.getOperand(0) == N1.getOperand(0) &&
peekThroughZext(N0.getOperand(2)) == peekThroughZext(N1.getOperand(1)))
return N0;
// (fshr ?, X, Y) | (srl X, Y) --> fshr ?, X, Y
if (N0.getOpcode() == ISD::FSHR && N1.getOpcode() == ISD::SRL &&
N0.getOperand(1) == N1.getOperand(0) &&
peekThroughZext(N0.getOperand(2)) == peekThroughZext(N1.getOperand(1)))
return N0;
return SDValue();
}
SDValue DAGCombiner::visitOR(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N1.getValueType();
// x | x --> x
if (N0 == N1)
return N0;
// fold (or c1, c2) -> c1|c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::OR, SDLoc(N), VT, {N0, N1}))
return C;
// canonicalize constant to RHS
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(ISD::OR, SDLoc(N), VT, N1, N0);
// fold vector ops
if (VT.isVector()) {
if (SDValue FoldedVOp = SimplifyVBinOp(N, SDLoc(N)))
return FoldedVOp;
// fold (or x, 0) -> x, vector edition
if (ISD::isConstantSplatVectorAllZeros(N1.getNode()))
return N0;
// fold (or x, -1) -> -1, vector edition
if (ISD::isConstantSplatVectorAllOnes(N1.getNode()))
// do not return N1, because undef node may exist in N1
return DAG.getAllOnesConstant(SDLoc(N), N1.getValueType());
// fold (or (shuf A, V_0, MA), (shuf B, V_0, MB)) -> (shuf A, B, Mask)
// Do this only if the resulting type / shuffle is legal.
auto *SV0 = dyn_cast<ShuffleVectorSDNode>(N0);
auto *SV1 = dyn_cast<ShuffleVectorSDNode>(N1);
if (SV0 && SV1 && TLI.isTypeLegal(VT)) {
bool ZeroN00 = ISD::isBuildVectorAllZeros(N0.getOperand(0).getNode());
bool ZeroN01 = ISD::isBuildVectorAllZeros(N0.getOperand(1).getNode());
bool ZeroN10 = ISD::isBuildVectorAllZeros(N1.getOperand(0).getNode());
bool ZeroN11 = ISD::isBuildVectorAllZeros(N1.getOperand(1).getNode());
// Ensure both shuffles have a zero input.
if ((ZeroN00 != ZeroN01) && (ZeroN10 != ZeroN11)) {
assert((!ZeroN00 || !ZeroN01) && "Both inputs zero!");
assert((!ZeroN10 || !ZeroN11) && "Both inputs zero!");
bool CanFold = true;
int NumElts = VT.getVectorNumElements();
SmallVector<int, 4> Mask(NumElts, -1);
for (int i = 0; i != NumElts; ++i) {
int M0 = SV0->getMaskElt(i);
int M1 = SV1->getMaskElt(i);
// Determine if either index is pointing to a zero vector.
bool M0Zero = M0 < 0 || (ZeroN00 == (M0 < NumElts));
bool M1Zero = M1 < 0 || (ZeroN10 == (M1 < NumElts));
// If one element is zero and the otherside is undef, keep undef.
// This also handles the case that both are undef.
if ((M0Zero && M1 < 0) || (M1Zero && M0 < 0))
continue;
// Make sure only one of the elements is zero.
if (M0Zero == M1Zero) {
CanFold = false;
break;
}
assert((M0 >= 0 || M1 >= 0) && "Undef index!");
// We have a zero and non-zero element. If the non-zero came from
// SV0 make the index a LHS index. If it came from SV1, make it
// a RHS index. We need to mod by NumElts because we don't care
// which operand it came from in the original shuffles.
Mask[i] = M1Zero ? M0 % NumElts : (M1 % NumElts) + NumElts;
}
if (CanFold) {
SDValue NewLHS = ZeroN00 ? N0.getOperand(1) : N0.getOperand(0);
SDValue NewRHS = ZeroN10 ? N1.getOperand(1) : N1.getOperand(0);
SDValue LegalShuffle =
TLI.buildLegalVectorShuffle(VT, SDLoc(N), NewLHS, NewRHS,
Mask, DAG);
if (LegalShuffle)
return LegalShuffle;
}
}
}
}
// fold (or x, 0) -> x
if (isNullConstant(N1))
return N0;
// fold (or x, -1) -> -1
if (isAllOnesConstant(N1))
return N1;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
// fold (or x, c) -> c iff (x & ~c) == 0
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
if (N1C && DAG.MaskedValueIsZero(N0, ~N1C->getAPIntValue()))
return N1;
if (SDValue Combined = visitORLike(N0, N1, N))
return Combined;
if (SDValue Combined = combineCarryDiamond(DAG, TLI, N0, N1, N))
return Combined;
// Recognize halfword bswaps as (bswap + rotl 16) or (bswap + shl 16)
if (SDValue BSwap = MatchBSwapHWord(N, N0, N1))
return BSwap;
if (SDValue BSwap = MatchBSwapHWordLow(N, N0, N1))
return BSwap;
// reassociate or
if (SDValue ROR = reassociateOps(ISD::OR, SDLoc(N), N0, N1, N->getFlags()))
return ROR;
// Canonicalize (or (and X, c1), c2) -> (and (or X, c2), c1|c2)
// iff (c1 & c2) != 0 or c1/c2 are undef.
auto MatchIntersect = [](ConstantSDNode *C1, ConstantSDNode *C2) {
return !C1 || !C2 || C1->getAPIntValue().intersects(C2->getAPIntValue());
};
if (N0.getOpcode() == ISD::AND && N0->hasOneUse() &&
ISD::matchBinaryPredicate(N0.getOperand(1), N1, MatchIntersect, true)) {
if (SDValue COR = DAG.FoldConstantArithmetic(ISD::OR, SDLoc(N1), VT,
{N1, N0.getOperand(1)})) {
SDValue IOR = DAG.getNode(ISD::OR, SDLoc(N0), VT, N0.getOperand(0), N1);
AddToWorklist(IOR.getNode());
return DAG.getNode(ISD::AND, SDLoc(N), VT, COR, IOR);
}
}
if (SDValue Combined = visitORCommutative(DAG, N0, N1, N))
return Combined;
if (SDValue Combined = visitORCommutative(DAG, N1, N0, N))
return Combined;
// Simplify: (or (op x...), (op y...)) -> (op (or x, y))
if (N0.getOpcode() == N1.getOpcode())
if (SDValue V = hoistLogicOpWithSameOpcodeHands(N))
return V;
// See if this is some rotate idiom.
if (SDValue Rot = MatchRotate(N0, N1, SDLoc(N)))
return Rot;
if (SDValue Load = MatchLoadCombine(N))
return Load;
// Simplify the operands using demanded-bits information.
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
// If OR can be rewritten into ADD, try combines based on ADD.
if ((!LegalOperations || TLI.isOperationLegal(ISD::ADD, VT)) &&
DAG.haveNoCommonBitsSet(N0, N1))
if (SDValue Combined = visitADDLike(N))
return Combined;
return SDValue();
}
static SDValue stripConstantMask(SelectionDAG &DAG, SDValue Op, SDValue &Mask) {
if (Op.getOpcode() == ISD::AND &&
DAG.isConstantIntBuildVectorOrConstantInt(Op.getOperand(1))) {
Mask = Op.getOperand(1);
return Op.getOperand(0);
}
return Op;
}
/// Match "(X shl/srl V1) & V2" where V2 may not be present.
static bool matchRotateHalf(SelectionDAG &DAG, SDValue Op, SDValue &Shift,
SDValue &Mask) {
Op = stripConstantMask(DAG, Op, Mask);
if (Op.getOpcode() == ISD::SRL || Op.getOpcode() == ISD::SHL) {
Shift = Op;
return true;
}
return false;
}
/// Helper function for visitOR to extract the needed side of a rotate idiom
/// from a shl/srl/mul/udiv. This is meant to handle cases where
/// InstCombine merged some outside op with one of the shifts from
/// the rotate pattern.
/// \returns An empty \c SDValue if the needed shift couldn't be extracted.
/// Otherwise, returns an expansion of \p ExtractFrom based on the following
/// patterns:
///
/// (or (add v v) (shrl v bitwidth-1)):
/// expands (add v v) -> (shl v 1)
///
/// (or (mul v c0) (shrl (mul v c1) c2)):
/// expands (mul v c0) -> (shl (mul v c1) c3)
///
/// (or (udiv v c0) (shl (udiv v c1) c2)):
/// expands (udiv v c0) -> (shrl (udiv v c1) c3)
///
/// (or (shl v c0) (shrl (shl v c1) c2)):
/// expands (shl v c0) -> (shl (shl v c1) c3)
///
/// (or (shrl v c0) (shl (shrl v c1) c2)):
/// expands (shrl v c0) -> (shrl (shrl v c1) c3)
///
/// Such that in all cases, c3+c2==bitwidth(op v c1).
static SDValue extractShiftForRotate(SelectionDAG &DAG, SDValue OppShift,
SDValue ExtractFrom, SDValue &Mask,
const SDLoc &DL) {
assert(OppShift && ExtractFrom && "Empty SDValue");
assert(
(OppShift.getOpcode() == ISD::SHL || OppShift.getOpcode() == ISD::SRL) &&
"Existing shift must be valid as a rotate half");
ExtractFrom = stripConstantMask(DAG, ExtractFrom, Mask);
// Value and Type of the shift.
SDValue OppShiftLHS = OppShift.getOperand(0);
EVT ShiftedVT = OppShiftLHS.getValueType();
// Amount of the existing shift.
ConstantSDNode *OppShiftCst = isConstOrConstSplat(OppShift.getOperand(1));
// (add v v) -> (shl v 1)
// TODO: Should this be a general DAG canonicalization?
if (OppShift.getOpcode() == ISD::SRL && OppShiftCst &&
ExtractFrom.getOpcode() == ISD::ADD &&
ExtractFrom.getOperand(0) == ExtractFrom.getOperand(1) &&
ExtractFrom.getOperand(0) == OppShiftLHS &&
OppShiftCst->getAPIntValue() == ShiftedVT.getScalarSizeInBits() - 1)
return DAG.getNode(ISD::SHL, DL, ShiftedVT, OppShiftLHS,
DAG.getShiftAmountConstant(1, ShiftedVT, DL));
// Preconditions:
// (or (op0 v c0) (shiftl/r (op0 v c1) c2))
//
// Find opcode of the needed shift to be extracted from (op0 v c0).
unsigned Opcode = ISD::DELETED_NODE;
bool IsMulOrDiv = false;
// Set Opcode and IsMulOrDiv if the extract opcode matches the needed shift
// opcode or its arithmetic (mul or udiv) variant.
auto SelectOpcode = [&](unsigned NeededShift, unsigned MulOrDivVariant) {
IsMulOrDiv = ExtractFrom.getOpcode() == MulOrDivVariant;
if (!IsMulOrDiv && ExtractFrom.getOpcode() != NeededShift)
return false;
Opcode = NeededShift;
return true;
};
// op0 must be either the needed shift opcode or the mul/udiv equivalent
// that the needed shift can be extracted from.
if ((OppShift.getOpcode() != ISD::SRL || !SelectOpcode(ISD::SHL, ISD::MUL)) &&
(OppShift.getOpcode() != ISD::SHL || !SelectOpcode(ISD::SRL, ISD::UDIV)))
return SDValue();
// op0 must be the same opcode on both sides, have the same LHS argument,
// and produce the same value type.
if (OppShiftLHS.getOpcode() != ExtractFrom.getOpcode() ||
OppShiftLHS.getOperand(0) != ExtractFrom.getOperand(0) ||
ShiftedVT != ExtractFrom.getValueType())
return SDValue();
// Constant mul/udiv/shift amount from the RHS of the shift's LHS op.
ConstantSDNode *OppLHSCst = isConstOrConstSplat(OppShiftLHS.getOperand(1));
// Constant mul/udiv/shift amount from the RHS of the ExtractFrom op.
ConstantSDNode *ExtractFromCst =
isConstOrConstSplat(ExtractFrom.getOperand(1));
// TODO: We should be able to handle non-uniform constant vectors for these values
// Check that we have constant values.
if (!OppShiftCst || !OppShiftCst->getAPIntValue() ||
!OppLHSCst || !OppLHSCst->getAPIntValue() ||
!ExtractFromCst || !ExtractFromCst->getAPIntValue())
return SDValue();
// Compute the shift amount we need to extract to complete the rotate.
const unsigned VTWidth = ShiftedVT.getScalarSizeInBits();
if (OppShiftCst->getAPIntValue().ugt(VTWidth))
return SDValue();
APInt NeededShiftAmt = VTWidth - OppShiftCst->getAPIntValue();
// Normalize the bitwidth of the two mul/udiv/shift constant operands.
APInt ExtractFromAmt = ExtractFromCst->getAPIntValue();
APInt OppLHSAmt = OppLHSCst->getAPIntValue();
zeroExtendToMatch(ExtractFromAmt, OppLHSAmt);
// Now try extract the needed shift from the ExtractFrom op and see if the
// result matches up with the existing shift's LHS op.
if (IsMulOrDiv) {
// Op to extract from is a mul or udiv by a constant.
// Check:
// c2 / (1 << (bitwidth(op0 v c0) - c1)) == c0
// c2 % (1 << (bitwidth(op0 v c0) - c1)) == 0
const APInt ExtractDiv = APInt::getOneBitSet(ExtractFromAmt.getBitWidth(),
NeededShiftAmt.getZExtValue());
APInt ResultAmt;
APInt Rem;
APInt::udivrem(ExtractFromAmt, ExtractDiv, ResultAmt, Rem);
if (Rem != 0 || ResultAmt != OppLHSAmt)
return SDValue();
} else {
// Op to extract from is a shift by a constant.
// Check:
// c2 - (bitwidth(op0 v c0) - c1) == c0
if (OppLHSAmt != ExtractFromAmt - NeededShiftAmt.zextOrTrunc(
ExtractFromAmt.getBitWidth()))
return SDValue();
}
// Return the expanded shift op that should allow a rotate to be formed.
EVT ShiftVT = OppShift.getOperand(1).getValueType();
EVT ResVT = ExtractFrom.getValueType();
SDValue NewShiftNode = DAG.getConstant(NeededShiftAmt, DL, ShiftVT);
return DAG.getNode(Opcode, DL, ResVT, OppShiftLHS, NewShiftNode);
}
// Return true if we can prove that, whenever Neg and Pos are both in the
// range [0, EltSize), Neg == (Pos == 0 ? 0 : EltSize - Pos). This means that
// for two opposing shifts shift1 and shift2 and a value X with OpBits bits:
//
// (or (shift1 X, Neg), (shift2 X, Pos))
//
// reduces to a rotate in direction shift2 by Pos or (equivalently) a rotate
// in direction shift1 by Neg. The range [0, EltSize) means that we only need
// to consider shift amounts with defined behavior.
//
// The IsRotate flag should be set when the LHS of both shifts is the same.
// Otherwise if matching a general funnel shift, it should be clear.
static bool matchRotateSub(SDValue Pos, SDValue Neg, unsigned EltSize,
SelectionDAG &DAG, bool IsRotate) {
// If EltSize is a power of 2 then:
//
// (a) (Pos == 0 ? 0 : EltSize - Pos) == (EltSize - Pos) & (EltSize - 1)
// (b) Neg == Neg & (EltSize - 1) whenever Neg is in [0, EltSize).
//
// So if EltSize is a power of 2 and Neg is (and Neg', EltSize-1), we check
// for the stronger condition:
//
// Neg & (EltSize - 1) == (EltSize - Pos) & (EltSize - 1) [A]
//
// for all Neg and Pos. Since Neg & (EltSize - 1) == Neg' & (EltSize - 1)
// we can just replace Neg with Neg' for the rest of the function.
//
// In other cases we check for the even stronger condition:
//
// Neg == EltSize - Pos [B]
//
// for all Neg and Pos. Note that the (or ...) then invokes undefined
// behavior if Pos == 0 (and consequently Neg == EltSize).
//
// We could actually use [A] whenever EltSize is a power of 2, but the
// only extra cases that it would match are those uninteresting ones
// where Neg and Pos are never in range at the same time. E.g. for
// EltSize == 32, using [A] would allow a Neg of the form (sub 64, Pos)
// as well as (sub 32, Pos), but:
//
// (or (shift1 X, (sub 64, Pos)), (shift2 X, Pos))
//
// always invokes undefined behavior for 32-bit X.
//
// Below, Mask == EltSize - 1 when using [A] and is all-ones otherwise.
//
// NOTE: We can only do this when matching an AND and not a general
// funnel shift.
unsigned MaskLoBits = 0;
if (IsRotate && Neg.getOpcode() == ISD::AND && isPowerOf2_64(EltSize)) {
if (ConstantSDNode *NegC = isConstOrConstSplat(Neg.getOperand(1))) {
KnownBits Known = DAG.computeKnownBits(Neg.getOperand(0));
unsigned Bits = Log2_64(EltSize);
if (NegC->getAPIntValue().getActiveBits() <= Bits &&
((NegC->getAPIntValue() | Known.Zero).countTrailingOnes() >= Bits)) {
Neg = Neg.getOperand(0);
MaskLoBits = Bits;
}
}
}
// Check whether Neg has the form (sub NegC, NegOp1) for some NegC and NegOp1.
if (Neg.getOpcode() != ISD::SUB)
return false;
ConstantSDNode *NegC = isConstOrConstSplat(Neg.getOperand(0));
if (!NegC)
return false;
SDValue NegOp1 = Neg.getOperand(1);
// On the RHS of [A], if Pos is Pos' & (EltSize - 1), just replace Pos with
// Pos'. The truncation is redundant for the purpose of the equality.
if (MaskLoBits && Pos.getOpcode() == ISD::AND) {
if (ConstantSDNode *PosC = isConstOrConstSplat(Pos.getOperand(1))) {
KnownBits Known = DAG.computeKnownBits(Pos.getOperand(0));
if (PosC->getAPIntValue().getActiveBits() <= MaskLoBits &&
((PosC->getAPIntValue() | Known.Zero).countTrailingOnes() >=
MaskLoBits))
Pos = Pos.getOperand(0);
}
}
// The condition we need is now:
//
// (NegC - NegOp1) & Mask == (EltSize - Pos) & Mask
//
// If NegOp1 == Pos then we need:
//
// EltSize & Mask == NegC & Mask
//
// (because "x & Mask" is a truncation and distributes through subtraction).
//
// We also need to account for a potential truncation of NegOp1 if the amount
// has already been legalized to a shift amount type.
APInt Width;
if ((Pos == NegOp1) ||
(NegOp1.getOpcode() == ISD::TRUNCATE && Pos == NegOp1.getOperand(0)))
Width = NegC->getAPIntValue();
// Check for cases where Pos has the form (add NegOp1, PosC) for some PosC.
// Then the condition we want to prove becomes:
//
// (NegC - NegOp1) & Mask == (EltSize - (NegOp1 + PosC)) & Mask
//
// which, again because "x & Mask" is a truncation, becomes:
//
// NegC & Mask == (EltSize - PosC) & Mask
// EltSize & Mask == (NegC + PosC) & Mask
else if (Pos.getOpcode() == ISD::ADD && Pos.getOperand(0) == NegOp1) {
if (ConstantSDNode *PosC = isConstOrConstSplat(Pos.getOperand(1)))
Width = PosC->getAPIntValue() + NegC->getAPIntValue();
else
return false;
} else
return false;
// Now we just need to check that EltSize & Mask == Width & Mask.
if (MaskLoBits)
// EltSize & Mask is 0 since Mask is EltSize - 1.
return Width.getLoBits(MaskLoBits) == 0;
return Width == EltSize;
}
// A subroutine of MatchRotate used once we have found an OR of two opposite
// shifts of Shifted. If Neg == <operand size> - Pos then the OR reduces
// to both (PosOpcode Shifted, Pos) and (NegOpcode Shifted, Neg), with the
// former being preferred if supported. InnerPos and InnerNeg are Pos and
// Neg with outer conversions stripped away.
SDValue DAGCombiner::MatchRotatePosNeg(SDValue Shifted, SDValue Pos,
SDValue Neg, SDValue InnerPos,
SDValue InnerNeg, bool HasPos,
unsigned PosOpcode, unsigned NegOpcode,
const SDLoc &DL) {
// fold (or (shl x, (*ext y)),
// (srl x, (*ext (sub 32, y)))) ->
// (rotl x, y) or (rotr x, (sub 32, y))
//
// fold (or (shl x, (*ext (sub 32, y))),
// (srl x, (*ext y))) ->
// (rotr x, y) or (rotl x, (sub 32, y))
EVT VT = Shifted.getValueType();
if (matchRotateSub(InnerPos, InnerNeg, VT.getScalarSizeInBits(), DAG,
/*IsRotate*/ true)) {
return DAG.getNode(HasPos ? PosOpcode : NegOpcode, DL, VT, Shifted,
HasPos ? Pos : Neg);
}
return SDValue();
}
// A subroutine of MatchRotate used once we have found an OR of two opposite
// shifts of N0 + N1. If Neg == <operand size> - Pos then the OR reduces
// to both (PosOpcode N0, N1, Pos) and (NegOpcode N0, N1, Neg), with the
// former being preferred if supported. InnerPos and InnerNeg are Pos and
// Neg with outer conversions stripped away.
// TODO: Merge with MatchRotatePosNeg.
SDValue DAGCombiner::MatchFunnelPosNeg(SDValue N0, SDValue N1, SDValue Pos,
SDValue Neg, SDValue InnerPos,
SDValue InnerNeg, bool HasPos,
unsigned PosOpcode, unsigned NegOpcode,
const SDLoc &DL) {
EVT VT = N0.getValueType();
unsigned EltBits = VT.getScalarSizeInBits();
// fold (or (shl x0, (*ext y)),
// (srl x1, (*ext (sub 32, y)))) ->
// (fshl x0, x1, y) or (fshr x0, x1, (sub 32, y))
//
// fold (or (shl x0, (*ext (sub 32, y))),
// (srl x1, (*ext y))) ->
// (fshr x0, x1, y) or (fshl x0, x1, (sub 32, y))
if (matchRotateSub(InnerPos, InnerNeg, EltBits, DAG, /*IsRotate*/ N0 == N1)) {
return DAG.getNode(HasPos ? PosOpcode : NegOpcode, DL, VT, N0, N1,
HasPos ? Pos : Neg);
}
// Matching the shift+xor cases, we can't easily use the xor'd shift amount
// so for now just use the PosOpcode case if its legal.
// TODO: When can we use the NegOpcode case?
if (PosOpcode == ISD::FSHL && isPowerOf2_32(EltBits)) {
auto IsBinOpImm = [](SDValue Op, unsigned BinOpc, unsigned Imm) {
if (Op.getOpcode() != BinOpc)
return false;
ConstantSDNode *Cst = isConstOrConstSplat(Op.getOperand(1));
return Cst && (Cst->getAPIntValue() == Imm);
};
// fold (or (shl x0, y), (srl (srl x1, 1), (xor y, 31)))
// -> (fshl x0, x1, y)
if (IsBinOpImm(N1, ISD::SRL, 1) &&
IsBinOpImm(InnerNeg, ISD::XOR, EltBits - 1) &&
InnerPos == InnerNeg.getOperand(0) &&
TLI.isOperationLegalOrCustom(ISD::FSHL, VT)) {
return DAG.getNode(ISD::FSHL, DL, VT, N0, N1.getOperand(0), Pos);
}
// fold (or (shl (shl x0, 1), (xor y, 31)), (srl x1, y))
// -> (fshr x0, x1, y)
if (IsBinOpImm(N0, ISD::SHL, 1) &&
IsBinOpImm(InnerPos, ISD::XOR, EltBits - 1) &&
InnerNeg == InnerPos.getOperand(0) &&
TLI.isOperationLegalOrCustom(ISD::FSHR, VT)) {
return DAG.getNode(ISD::FSHR, DL, VT, N0.getOperand(0), N1, Neg);
}
// fold (or (shl (add x0, x0), (xor y, 31)), (srl x1, y))
// -> (fshr x0, x1, y)
// TODO: Should add(x,x) -> shl(x,1) be a general DAG canonicalization?
if (N0.getOpcode() == ISD::ADD && N0.getOperand(0) == N0.getOperand(1) &&
IsBinOpImm(InnerPos, ISD::XOR, EltBits - 1) &&
InnerNeg == InnerPos.getOperand(0) &&
TLI.isOperationLegalOrCustom(ISD::FSHR, VT)) {
return DAG.getNode(ISD::FSHR, DL, VT, N0.getOperand(0), N1, Neg);
}
}
return SDValue();
}
// MatchRotate - Handle an 'or' of two operands. If this is one of the many
// idioms for rotate, and if the target supports rotation instructions, generate
// a rot[lr]. This also matches funnel shift patterns, similar to rotation but
// with different shifted sources.
SDValue DAGCombiner::MatchRotate(SDValue LHS, SDValue RHS, const SDLoc &DL) {
EVT VT = LHS.getValueType();
// The target must have at least one rotate/funnel flavor.
// We still try to match rotate by constant pre-legalization.
// TODO: Support pre-legalization funnel-shift by constant.
bool HasROTL = hasOperation(ISD::ROTL, VT);
bool HasROTR = hasOperation(ISD::ROTR, VT);
bool HasFSHL = hasOperation(ISD::FSHL, VT);
bool HasFSHR = hasOperation(ISD::FSHR, VT);
// If the type is going to be promoted and the target has enabled custom
// lowering for rotate, allow matching rotate by non-constants. Only allow
// this for scalar types.
if (VT.isScalarInteger() && TLI.getTypeAction(*DAG.getContext(), VT) ==
TargetLowering::TypePromoteInteger) {
HasROTL |= TLI.getOperationAction(ISD::ROTL, VT) == TargetLowering::Custom;
HasROTR |= TLI.getOperationAction(ISD::ROTR, VT) == TargetLowering::Custom;
}
if (LegalOperations && !HasROTL && !HasROTR && !HasFSHL && !HasFSHR)
return SDValue();
// Check for truncated rotate.
if (LHS.getOpcode() == ISD::TRUNCATE && RHS.getOpcode() == ISD::TRUNCATE &&
LHS.getOperand(0).getValueType() == RHS.getOperand(0).getValueType()) {
assert(LHS.getValueType() == RHS.getValueType());
if (SDValue Rot = MatchRotate(LHS.getOperand(0), RHS.getOperand(0), DL)) {
return DAG.getNode(ISD::TRUNCATE, SDLoc(LHS), LHS.getValueType(), Rot);
}
}
// Match "(X shl/srl V1) & V2" where V2 may not be present.
SDValue LHSShift; // The shift.
SDValue LHSMask; // AND value if any.
matchRotateHalf(DAG, LHS, LHSShift, LHSMask);
SDValue RHSShift; // The shift.
SDValue RHSMask; // AND value if any.
matchRotateHalf(DAG, RHS, RHSShift, RHSMask);
// If neither side matched a rotate half, bail
if (!LHSShift && !RHSShift)
return SDValue();
// InstCombine may have combined a constant shl, srl, mul, or udiv with one
// side of the rotate, so try to handle that here. In all cases we need to
// pass the matched shift from the opposite side to compute the opcode and
// needed shift amount to extract. We still want to do this if both sides
// matched a rotate half because one half may be a potential overshift that
// can be broken down (ie if InstCombine merged two shl or srl ops into a
// single one).
// Have LHS side of the rotate, try to extract the needed shift from the RHS.
if (LHSShift)
if (SDValue NewRHSShift =
extractShiftForRotate(DAG, LHSShift, RHS, RHSMask, DL))
RHSShift = NewRHSShift;
// Have RHS side of the rotate, try to extract the needed shift from the LHS.
if (RHSShift)
if (SDValue NewLHSShift =
extractShiftForRotate(DAG, RHSShift, LHS, LHSMask, DL))
LHSShift = NewLHSShift;
// If a side is still missing, nothing else we can do.
if (!RHSShift || !LHSShift)
return SDValue();
// At this point we've matched or extracted a shift op on each side.
if (LHSShift.getOpcode() == RHSShift.getOpcode())
return SDValue(); // Shifts must disagree.
// Canonicalize shl to left side in a shl/srl pair.
if (RHSShift.getOpcode() == ISD::SHL) {
std::swap(LHS, RHS);
std::swap(LHSShift, RHSShift);
std::swap(LHSMask, RHSMask);
}
unsigned EltSizeInBits = VT.getScalarSizeInBits();
SDValue LHSShiftArg = LHSShift.getOperand(0);
SDValue LHSShiftAmt = LHSShift.getOperand(1);
SDValue RHSShiftArg = RHSShift.getOperand(0);
SDValue RHSShiftAmt = RHSShift.getOperand(1);
auto MatchRotateSum = [EltSizeInBits](ConstantSDNode *LHS,
ConstantSDNode *RHS) {
return (LHS->getAPIntValue() + RHS->getAPIntValue()) == EltSizeInBits;
};
auto ApplyMasks = [&](SDValue Res) {
// If there is an AND of either shifted operand, apply it to the result.
if (LHSMask.getNode() || RHSMask.getNode()) {
SDValue AllOnes = DAG.getAllOnesConstant(DL, VT);
SDValue Mask = AllOnes;
if (LHSMask.getNode()) {
SDValue RHSBits = DAG.getNode(ISD::SRL, DL, VT, AllOnes, RHSShiftAmt);
Mask = DAG.getNode(ISD::AND, DL, VT, Mask,
DAG.getNode(ISD::OR, DL, VT, LHSMask, RHSBits));
}
if (RHSMask.getNode()) {
SDValue LHSBits = DAG.getNode(ISD::SHL, DL, VT, AllOnes, LHSShiftAmt);
Mask = DAG.getNode(ISD::AND, DL, VT, Mask,
DAG.getNode(ISD::OR, DL, VT, RHSMask, LHSBits));
}
Res = DAG.getNode(ISD::AND, DL, VT, Res, Mask);
}
return Res;
};
// TODO: Support pre-legalization funnel-shift by constant.
bool IsRotate = LHSShift.getOperand(0) == RHSShift.getOperand(0);
if (!IsRotate && !(HasFSHL || HasFSHR)) {
if (TLI.isTypeLegal(VT) && LHS.hasOneUse() && RHS.hasOneUse() &&
ISD::matchBinaryPredicate(LHSShiftAmt, RHSShiftAmt, MatchRotateSum)) {
// Look for a disguised rotate by constant.
// The common shifted operand X may be hidden inside another 'or'.
SDValue X, Y;
auto matchOr = [&X, &Y](SDValue Or, SDValue CommonOp) {
if (!Or.hasOneUse() || Or.getOpcode() != ISD::OR)
return false;
if (CommonOp == Or.getOperand(0)) {
X = CommonOp;
Y = Or.getOperand(1);
return true;
}
if (CommonOp == Or.getOperand(1)) {
X = CommonOp;
Y = Or.getOperand(0);
return true;
}
return false;
};
SDValue Res;
if (matchOr(LHSShiftArg, RHSShiftArg)) {
// (shl (X | Y), C1) | (srl X, C2) --> (rotl X, C1) | (shl Y, C1)
SDValue RotX = DAG.getNode(ISD::ROTL, DL, VT, X, LHSShiftAmt);
SDValue ShlY = DAG.getNode(ISD::SHL, DL, VT, Y, LHSShiftAmt);
Res = DAG.getNode(ISD::OR, DL, VT, RotX, ShlY);
} else if (matchOr(RHSShiftArg, LHSShiftArg)) {
// (shl X, C1) | (srl (X | Y), C2) --> (rotl X, C1) | (srl Y, C2)
SDValue RotX = DAG.getNode(ISD::ROTL, DL, VT, X, LHSShiftAmt);
SDValue SrlY = DAG.getNode(ISD::SRL, DL, VT, Y, RHSShiftAmt);
Res = DAG.getNode(ISD::OR, DL, VT, RotX, SrlY);
} else {
return SDValue();
}
return ApplyMasks(Res);
}
return SDValue(); // Requires funnel shift support.
}
// fold (or (shl x, C1), (srl x, C2)) -> (rotl x, C1)
// fold (or (shl x, C1), (srl x, C2)) -> (rotr x, C2)
// fold (or (shl x, C1), (srl y, C2)) -> (fshl x, y, C1)
// fold (or (shl x, C1), (srl y, C2)) -> (fshr x, y, C2)
// iff C1+C2 == EltSizeInBits
if (ISD::matchBinaryPredicate(LHSShiftAmt, RHSShiftAmt, MatchRotateSum)) {
SDValue Res;
if (IsRotate && (HasROTL || HasROTR || !(HasFSHL || HasFSHR))) {
bool UseROTL = !LegalOperations || HasROTL;
Res = DAG.getNode(UseROTL ? ISD::ROTL : ISD::ROTR, DL, VT, LHSShiftArg,
UseROTL ? LHSShiftAmt : RHSShiftAmt);
} else {
bool UseFSHL = !LegalOperations || HasFSHL;
Res = DAG.getNode(UseFSHL ? ISD::FSHL : ISD::FSHR, DL, VT, LHSShiftArg,
RHSShiftArg, UseFSHL ? LHSShiftAmt : RHSShiftAmt);
}
return ApplyMasks(Res);
}
// Even pre-legalization, we can't easily rotate/funnel-shift by a variable
// shift.
if (!HasROTL && !HasROTR && !HasFSHL && !HasFSHR)
return SDValue();
// If there is a mask here, and we have a variable shift, we can't be sure
// that we're masking out the right stuff.
if (LHSMask.getNode() || RHSMask.getNode())
return SDValue();
// If the shift amount is sign/zext/any-extended just peel it off.
SDValue LExtOp0 = LHSShiftAmt;
SDValue RExtOp0 = RHSShiftAmt;
if ((LHSShiftAmt.getOpcode() == ISD::SIGN_EXTEND ||
LHSShiftAmt.getOpcode() == ISD::ZERO_EXTEND ||
LHSShiftAmt.getOpcode() == ISD::ANY_EXTEND ||
LHSShiftAmt.getOpcode() == ISD::TRUNCATE) &&
(RHSShiftAmt.getOpcode() == ISD::SIGN_EXTEND ||
RHSShiftAmt.getOpcode() == ISD::ZERO_EXTEND ||
RHSShiftAmt.getOpcode() == ISD::ANY_EXTEND ||
RHSShiftAmt.getOpcode() == ISD::TRUNCATE)) {
LExtOp0 = LHSShiftAmt.getOperand(0);
RExtOp0 = RHSShiftAmt.getOperand(0);
}
if (IsRotate && (HasROTL || HasROTR)) {
SDValue TryL =
MatchRotatePosNeg(LHSShiftArg, LHSShiftAmt, RHSShiftAmt, LExtOp0,
RExtOp0, HasROTL, ISD::ROTL, ISD::ROTR, DL);
if (TryL)
return TryL;
SDValue TryR =
MatchRotatePosNeg(RHSShiftArg, RHSShiftAmt, LHSShiftAmt, RExtOp0,
LExtOp0, HasROTR, ISD::ROTR, ISD::ROTL, DL);
if (TryR)
return TryR;
}
SDValue TryL =
MatchFunnelPosNeg(LHSShiftArg, RHSShiftArg, LHSShiftAmt, RHSShiftAmt,
LExtOp0, RExtOp0, HasFSHL, ISD::FSHL, ISD::FSHR, DL);
if (TryL)
return TryL;
SDValue TryR =
MatchFunnelPosNeg(LHSShiftArg, RHSShiftArg, RHSShiftAmt, LHSShiftAmt,
RExtOp0, LExtOp0, HasFSHR, ISD::FSHR, ISD::FSHL, DL);
if (TryR)
return TryR;
return SDValue();
}
namespace {
/// Represents known origin of an individual byte in load combine pattern. The
/// value of the byte is either constant zero or comes from memory.
struct ByteProvider {
// For constant zero providers Load is set to nullptr. For memory providers
// Load represents the node which loads the byte from memory.
// ByteOffset is the offset of the byte in the value produced by the load.
LoadSDNode *Load = nullptr;
unsigned ByteOffset = 0;
ByteProvider() = default;
static ByteProvider getMemory(LoadSDNode *Load, unsigned ByteOffset) {
return ByteProvider(Load, ByteOffset);
}
static ByteProvider getConstantZero() { return ByteProvider(nullptr, 0); }
bool isConstantZero() const { return !Load; }
bool isMemory() const { return Load; }
bool operator==(const ByteProvider &Other) const {
return Other.Load == Load && Other.ByteOffset == ByteOffset;
}
private:
ByteProvider(LoadSDNode *Load, unsigned ByteOffset)
: Load(Load), ByteOffset(ByteOffset) {}
};
} // end anonymous namespace
/// Recursively traverses the expression calculating the origin of the requested
/// byte of the given value. Returns None if the provider can't be calculated.
///
/// For all the values except the root of the expression verifies that the value
/// has exactly one use and if it's not true return None. This way if the origin
/// of the byte is returned it's guaranteed that the values which contribute to
/// the byte are not used outside of this expression.
///
/// Because the parts of the expression are not allowed to have more than one
/// use this function iterates over trees, not DAGs. So it never visits the same
/// node more than once.
static const Optional<ByteProvider>
calculateByteProvider(SDValue Op, unsigned Index, unsigned Depth,
bool Root = false) {
// Typical i64 by i8 pattern requires recursion up to 8 calls depth
if (Depth == 10)
return None;
if (!Root && !Op.hasOneUse())
return None;
assert(Op.getValueType().isScalarInteger() && "can't handle other types");
unsigned BitWidth = Op.getValueSizeInBits();
if (BitWidth % 8 != 0)
return None;
unsigned ByteWidth = BitWidth / 8;
assert(Index < ByteWidth && "invalid index requested");
(void) ByteWidth;
switch (Op.getOpcode()) {
case ISD::OR: {
auto LHS = calculateByteProvider(Op->getOperand(0), Index, Depth + 1);
if (!LHS)
return None;
auto RHS = calculateByteProvider(Op->getOperand(1), Index, Depth + 1);
if (!RHS)
return None;
if (LHS->isConstantZero())
return RHS;
if (RHS->isConstantZero())
return LHS;
return None;
}
case ISD::SHL: {
auto ShiftOp = dyn_cast<ConstantSDNode>(Op->getOperand(1));
if (!ShiftOp)
return None;
uint64_t BitShift = ShiftOp->getZExtValue();
if (BitShift % 8 != 0)
return None;
uint64_t ByteShift = BitShift / 8;
return Index < ByteShift
? ByteProvider::getConstantZero()
: calculateByteProvider(Op->getOperand(0), Index - ByteShift,
Depth + 1);
}
case ISD::ANY_EXTEND:
case ISD::SIGN_EXTEND:
case ISD::ZERO_EXTEND: {
SDValue NarrowOp = Op->getOperand(0);
unsigned NarrowBitWidth = NarrowOp.getScalarValueSizeInBits();
if (NarrowBitWidth % 8 != 0)
return None;
uint64_t NarrowByteWidth = NarrowBitWidth / 8;
if (Index >= NarrowByteWidth)
return Op.getOpcode() == ISD::ZERO_EXTEND
? Optional<ByteProvider>(ByteProvider::getConstantZero())
: None;
return calculateByteProvider(NarrowOp, Index, Depth + 1);
}
case ISD::BSWAP:
return calculateByteProvider(Op->getOperand(0), ByteWidth - Index - 1,
Depth + 1);
case ISD::LOAD: {
auto L = cast<LoadSDNode>(Op.getNode());
if (!L->isSimple() || L->isIndexed())
return None;
unsigned NarrowBitWidth = L->getMemoryVT().getSizeInBits();
if (NarrowBitWidth % 8 != 0)
return None;
uint64_t NarrowByteWidth = NarrowBitWidth / 8;
if (Index >= NarrowByteWidth)
return L->getExtensionType() == ISD::ZEXTLOAD
? Optional<ByteProvider>(ByteProvider::getConstantZero())
: None;
return ByteProvider::getMemory(L, Index);
}
}
return None;
}
static unsigned littleEndianByteAt(unsigned BW, unsigned i) {
return i;
}
static unsigned bigEndianByteAt(unsigned BW, unsigned i) {
return BW - i - 1;
}
// Check if the bytes offsets we are looking at match with either big or
// little endian value loaded. Return true for big endian, false for little
// endian, and None if match failed.
static Optional<bool> isBigEndian(const ArrayRef<int64_t> ByteOffsets,
int64_t FirstOffset) {
// The endian can be decided only when it is 2 bytes at least.
unsigned Width = ByteOffsets.size();
if (Width < 2)
return None;
bool BigEndian = true, LittleEndian = true;
for (unsigned i = 0; i < Width; i++) {
int64_t CurrentByteOffset = ByteOffsets[i] - FirstOffset;
LittleEndian &= CurrentByteOffset == littleEndianByteAt(Width, i);
BigEndian &= CurrentByteOffset == bigEndianByteAt(Width, i);
if (!BigEndian && !LittleEndian)
return None;
}
assert((BigEndian != LittleEndian) && "It should be either big endian or"
"little endian");
return BigEndian;
}
static SDValue stripTruncAndExt(SDValue Value) {
switch (Value.getOpcode()) {
case ISD::TRUNCATE:
case ISD::ZERO_EXTEND:
case ISD::SIGN_EXTEND:
case ISD::ANY_EXTEND:
return stripTruncAndExt(Value.getOperand(0));
}
return Value;
}
/// Match a pattern where a wide type scalar value is stored by several narrow
/// stores. Fold it into a single store or a BSWAP and a store if the targets
/// supports it.
///
/// Assuming little endian target:
/// i8 *p = ...
/// i32 val = ...
/// p[0] = (val >> 0) & 0xFF;
/// p[1] = (val >> 8) & 0xFF;
/// p[2] = (val >> 16) & 0xFF;
/// p[3] = (val >> 24) & 0xFF;
/// =>
/// *((i32)p) = val;
///
/// i8 *p = ...
/// i32 val = ...
/// p[0] = (val >> 24) & 0xFF;
/// p[1] = (val >> 16) & 0xFF;
/// p[2] = (val >> 8) & 0xFF;
/// p[3] = (val >> 0) & 0xFF;
/// =>
/// *((i32)p) = BSWAP(val);
SDValue DAGCombiner::mergeTruncStores(StoreSDNode *N) {
// The matching looks for "store (trunc x)" patterns that appear early but are
// likely to be replaced by truncating store nodes during combining.
// TODO: If there is evidence that running this later would help, this
// limitation could be removed. Legality checks may need to be added
// for the created store and optional bswap/rotate.
if (LegalOperations || OptLevel == CodeGenOpt::None)
return SDValue();
// We only handle merging simple stores of 1-4 bytes.
// TODO: Allow unordered atomics when wider type is legal (see D66309)
EVT MemVT = N->getMemoryVT();
if (!(MemVT == MVT::i8 || MemVT == MVT::i16 || MemVT == MVT::i32) ||
!N->isSimple() || N->isIndexed())
return SDValue();
// Collect all of the stores in the chain.
SDValue Chain = N->getChain();
SmallVector<StoreSDNode *, 8> Stores = {N};
while (auto *Store = dyn_cast<StoreSDNode>(Chain)) {
// All stores must be the same size to ensure that we are writing all of the
// bytes in the wide value.
// TODO: We could allow multiple sizes by tracking each stored byte.
if (Store->getMemoryVT() != MemVT || !Store->isSimple() ||
Store->isIndexed())
return SDValue();
Stores.push_back(Store);
Chain = Store->getChain();
}
// There is no reason to continue if we do not have at least a pair of stores.
if (Stores.size() < 2)
return SDValue();
// Handle simple types only.
LLVMContext &Context = *DAG.getContext();
unsigned NumStores = Stores.size();
unsigned NarrowNumBits = N->getMemoryVT().getScalarSizeInBits();
unsigned WideNumBits = NumStores * NarrowNumBits;
EVT WideVT = EVT::getIntegerVT(Context, WideNumBits);
if (WideVT != MVT::i16 && WideVT != MVT::i32 && WideVT != MVT::i64)
return SDValue();
// Check if all bytes of the source value that we are looking at are stored
// to the same base address. Collect offsets from Base address into OffsetMap.
SDValue SourceValue;
SmallVector<int64_t, 8> OffsetMap(NumStores, INT64_MAX);
int64_t FirstOffset = INT64_MAX;
StoreSDNode *FirstStore = nullptr;
Optional<BaseIndexOffset> Base;
for (auto Store : Stores) {
// All the stores store different parts of the CombinedValue. A truncate is
// required to get the partial value.
SDValue Trunc = Store->getValue();
if (Trunc.getOpcode() != ISD::TRUNCATE)
return SDValue();
// Other than the first/last part, a shift operation is required to get the
// offset.
int64_t Offset = 0;
SDValue WideVal = Trunc.getOperand(0);
if ((WideVal.getOpcode() == ISD::SRL || WideVal.getOpcode() == ISD::SRA) &&
isa<ConstantSDNode>(WideVal.getOperand(1))) {
// The shift amount must be a constant multiple of the narrow type.
// It is translated to the offset address in the wide source value "y".
//
// x = srl y, ShiftAmtC
// i8 z = trunc x
// store z, ...
uint64_t ShiftAmtC = WideVal.getConstantOperandVal(1);
if (ShiftAmtC % NarrowNumBits != 0)
return SDValue();
Offset = ShiftAmtC / NarrowNumBits;
WideVal = WideVal.getOperand(0);
}
// Stores must share the same source value with different offsets.
// Truncate and extends should be stripped to get the single source value.
if (!SourceValue)
SourceValue = WideVal;
else if (stripTruncAndExt(SourceValue) != stripTruncAndExt(WideVal))
return SDValue();
else if (SourceValue.getValueType() != WideVT) {
if (WideVal.getValueType() == WideVT ||
WideVal.getScalarValueSizeInBits() >
SourceValue.getScalarValueSizeInBits())
SourceValue = WideVal;
// Give up if the source value type is smaller than the store size.
if (SourceValue.getScalarValueSizeInBits() < WideVT.getScalarSizeInBits())
return SDValue();
}
// Stores must share the same base address.
BaseIndexOffset Ptr = BaseIndexOffset::match(Store, DAG);
int64_t ByteOffsetFromBase = 0;
if (!Base)
Base = Ptr;
else if (!Base->equalBaseIndex(Ptr, DAG, ByteOffsetFromBase))
return SDValue();
// Remember the first store.
if (ByteOffsetFromBase < FirstOffset) {
FirstStore = Store;
FirstOffset = ByteOffsetFromBase;
}
// Map the offset in the store and the offset in the combined value, and
// early return if it has been set before.
if (Offset < 0 || Offset >= NumStores || OffsetMap[Offset] != INT64_MAX)
return SDValue();
OffsetMap[Offset] = ByteOffsetFromBase;
}
assert(FirstOffset != INT64_MAX && "First byte offset must be set");
assert(FirstStore && "First store must be set");
// Check that a store of the wide type is both allowed and fast on the target
const DataLayout &Layout = DAG.getDataLayout();
bool Fast = false;
bool Allowed = TLI.allowsMemoryAccess(Context, Layout, WideVT,
*FirstStore->getMemOperand(), &Fast);
if (!Allowed || !Fast)
return SDValue();
// Check if the pieces of the value are going to the expected places in memory
// to merge the stores.
auto checkOffsets = [&](bool MatchLittleEndian) {
if (MatchLittleEndian) {
for (unsigned i = 0; i != NumStores; ++i)
if (OffsetMap[i] != i * (NarrowNumBits / 8) + FirstOffset)
return false;
} else { // MatchBigEndian by reversing loop counter.
for (unsigned i = 0, j = NumStores - 1; i != NumStores; ++i, --j)
if (OffsetMap[j] != i * (NarrowNumBits / 8) + FirstOffset)
return false;
}
return true;
};
// Check if the offsets line up for the native data layout of this target.
bool NeedBswap = false;
bool NeedRotate = false;
if (!checkOffsets(Layout.isLittleEndian())) {
// Special-case: check if byte offsets line up for the opposite endian.
if (NarrowNumBits == 8 && checkOffsets(Layout.isBigEndian()))
NeedBswap = true;
else if (NumStores == 2 && checkOffsets(Layout.isBigEndian()))
NeedRotate = true;
else
return SDValue();
}
SDLoc DL(N);
if (WideVT != SourceValue.getValueType()) {
assert(SourceValue.getValueType().getScalarSizeInBits() > WideNumBits &&
"Unexpected store value to merge");
SourceValue = DAG.getNode(ISD::TRUNCATE, DL, WideVT, SourceValue);
}
// Before legalize we can introduce illegal bswaps/rotates which will be later
// converted to an explicit bswap sequence. This way we end up with a single
// store and byte shuffling instead of several stores and byte shuffling.
if (NeedBswap) {
SourceValue = DAG.getNode(ISD::BSWAP, DL, WideVT, SourceValue);
} else if (NeedRotate) {
assert(WideNumBits % 2 == 0 && "Unexpected type for rotate");
SDValue RotAmt = DAG.getConstant(WideNumBits / 2, DL, WideVT);
SourceValue = DAG.getNode(ISD::ROTR, DL, WideVT, SourceValue, RotAmt);
}
SDValue NewStore =
DAG.getStore(Chain, DL, SourceValue, FirstStore->getBasePtr(),
FirstStore->getPointerInfo(), FirstStore->getAlign());
// Rely on other DAG combine rules to remove the other individual stores.
DAG.ReplaceAllUsesWith(N, NewStore.getNode());
return NewStore;
}
/// Match a pattern where a wide type scalar value is loaded by several narrow
/// loads and combined by shifts and ors. Fold it into a single load or a load
/// and a BSWAP if the targets supports it.
///
/// Assuming little endian target:
/// i8 *a = ...
/// i32 val = a[0] | (a[1] << 8) | (a[2] << 16) | (a[3] << 24)
/// =>
/// i32 val = *((i32)a)
///
/// i8 *a = ...
/// i32 val = (a[0] << 24) | (a[1] << 16) | (a[2] << 8) | a[3]
/// =>
/// i32 val = BSWAP(*((i32)a))
///
/// TODO: This rule matches complex patterns with OR node roots and doesn't
/// interact well with the worklist mechanism. When a part of the pattern is
/// updated (e.g. one of the loads) its direct users are put into the worklist,
/// but the root node of the pattern which triggers the load combine is not
/// necessarily a direct user of the changed node. For example, once the address
/// of t28 load is reassociated load combine won't be triggered:
/// t25: i32 = add t4, Constant:i32<2>
/// t26: i64 = sign_extend t25
/// t27: i64 = add t2, t26
/// t28: i8,ch = load<LD1[%tmp9]> t0, t27, undef:i64
/// t29: i32 = zero_extend t28
/// t32: i32 = shl t29, Constant:i8<8>
/// t33: i32 = or t23, t32
/// As a possible fix visitLoad can check if the load can be a part of a load
/// combine pattern and add corresponding OR roots to the worklist.
SDValue DAGCombiner::MatchLoadCombine(SDNode *N) {
assert(N->getOpcode() == ISD::OR &&
"Can only match load combining against OR nodes");
// Handles simple types only
EVT VT = N->getValueType(0);
if (VT != MVT::i16 && VT != MVT::i32 && VT != MVT::i64)
return SDValue();
unsigned ByteWidth = VT.getSizeInBits() / 8;
bool IsBigEndianTarget = DAG.getDataLayout().isBigEndian();
auto MemoryByteOffset = [&] (ByteProvider P) {
assert(P.isMemory() && "Must be a memory byte provider");
unsigned LoadBitWidth = P.Load->getMemoryVT().getSizeInBits();
assert(LoadBitWidth % 8 == 0 &&
"can only analyze providers for individual bytes not bit");
unsigned LoadByteWidth = LoadBitWidth / 8;
return IsBigEndianTarget
? bigEndianByteAt(LoadByteWidth, P.ByteOffset)
: littleEndianByteAt(LoadByteWidth, P.ByteOffset);
};
Optional<BaseIndexOffset> Base;
SDValue Chain;
SmallPtrSet<LoadSDNode *, 8> Loads;
Optional<ByteProvider> FirstByteProvider;
int64_t FirstOffset = INT64_MAX;
// Check if all the bytes of the OR we are looking at are loaded from the same
// base address. Collect bytes offsets from Base address in ByteOffsets.
SmallVector<int64_t, 8> ByteOffsets(ByteWidth);
unsigned ZeroExtendedBytes = 0;
for (int i = ByteWidth - 1; i >= 0; --i) {
auto P = calculateByteProvider(SDValue(N, 0), i, 0, /*Root=*/true);
if (!P)
return SDValue();
if (P->isConstantZero()) {
// It's OK for the N most significant bytes to be 0, we can just
// zero-extend the load.
if (++ZeroExtendedBytes != (ByteWidth - static_cast<unsigned>(i)))
return SDValue();
continue;
}
assert(P->isMemory() && "provenance should either be memory or zero");
LoadSDNode *L = P->Load;
assert(L->hasNUsesOfValue(1, 0) && L->isSimple() &&
!L->isIndexed() &&
"Must be enforced by calculateByteProvider");
assert(L->getOffset().isUndef() && "Unindexed load must have undef offset");
// All loads must share the same chain
SDValue LChain = L->getChain();
if (!Chain)
Chain = LChain;
else if (Chain != LChain)
return SDValue();
// Loads must share the same base address
BaseIndexOffset Ptr = BaseIndexOffset::match(L, DAG);
int64_t ByteOffsetFromBase = 0;
if (!Base)
Base = Ptr;
else if (!Base->equalBaseIndex(Ptr, DAG, ByteOffsetFromBase))
return SDValue();
// Calculate the offset of the current byte from the base address
ByteOffsetFromBase += MemoryByteOffset(*P);
ByteOffsets[i] = ByteOffsetFromBase;
// Remember the first byte load
if (ByteOffsetFromBase < FirstOffset) {
FirstByteProvider = P;
FirstOffset = ByteOffsetFromBase;
}
Loads.insert(L);
}
assert(!Loads.empty() && "All the bytes of the value must be loaded from "
"memory, so there must be at least one load which produces the value");
assert(Base && "Base address of the accessed memory location must be set");
assert(FirstOffset != INT64_MAX && "First byte offset must be set");
bool NeedsZext = ZeroExtendedBytes > 0;
EVT MemVT =
EVT::getIntegerVT(*DAG.getContext(), (ByteWidth - ZeroExtendedBytes) * 8);
if (!MemVT.isSimple())
return SDValue();
// Before legalize we can introduce too wide illegal loads which will be later
// split into legal sized loads. This enables us to combine i64 load by i8
// patterns to a couple of i32 loads on 32 bit targets.
if (LegalOperations &&
!TLI.isOperationLegal(NeedsZext ? ISD::ZEXTLOAD : ISD::NON_EXTLOAD,
MemVT))
return SDValue();
// Check if the bytes of the OR we are looking at match with either big or
// little endian value load
Optional<bool> IsBigEndian = isBigEndian(
makeArrayRef(ByteOffsets).drop_back(ZeroExtendedBytes), FirstOffset);
if (!IsBigEndian.hasValue())
return SDValue();
assert(FirstByteProvider && "must be set");
// Ensure that the first byte is loaded from zero offset of the first load.
// So the combined value can be loaded from the first load address.
if (MemoryByteOffset(*FirstByteProvider) != 0)
return SDValue();
LoadSDNode *FirstLoad = FirstByteProvider->Load;
// The node we are looking at matches with the pattern, check if we can
// replace it with a single (possibly zero-extended) load and bswap + shift if
// needed.
// If the load needs byte swap check if the target supports it
bool NeedsBswap = IsBigEndianTarget != *IsBigEndian;
// Before legalize we can introduce illegal bswaps which will be later
// converted to an explicit bswap sequence. This way we end up with a single
// load and byte shuffling instead of several loads and byte shuffling.
// We do not introduce illegal bswaps when zero-extending as this tends to
// introduce too many arithmetic instructions.
if (NeedsBswap && (LegalOperations || NeedsZext) &&
!TLI.isOperationLegal(ISD::BSWAP, VT))
return SDValue();
// If we need to bswap and zero extend, we have to insert a shift. Check that
// it is legal.
if (NeedsBswap && NeedsZext && LegalOperations &&
!TLI.isOperationLegal(ISD::SHL, VT))
return SDValue();
// Check that a load of the wide type is both allowed and fast on the target
bool Fast = false;
bool Allowed =
TLI.allowsMemoryAccess(*DAG.getContext(), DAG.getDataLayout(), MemVT,
*FirstLoad->getMemOperand(), &Fast);
if (!Allowed || !Fast)
return SDValue();
SDValue NewLoad =
DAG.getExtLoad(NeedsZext ? ISD::ZEXTLOAD : ISD::NON_EXTLOAD, SDLoc(N), VT,
Chain, FirstLoad->getBasePtr(),
FirstLoad->getPointerInfo(), MemVT, FirstLoad->getAlign());
// Transfer chain users from old loads to the new load.
for (LoadSDNode *L : Loads)
DAG.ReplaceAllUsesOfValueWith(SDValue(L, 1), SDValue(NewLoad.getNode(), 1));
if (!NeedsBswap)
return NewLoad;
SDValue ShiftedLoad =
NeedsZext
? DAG.getNode(ISD::SHL, SDLoc(N), VT, NewLoad,
DAG.getShiftAmountConstant(ZeroExtendedBytes * 8, VT,
SDLoc(N), LegalOperations))
: NewLoad;
return DAG.getNode(ISD::BSWAP, SDLoc(N), VT, ShiftedLoad);
}
// If the target has andn, bsl, or a similar bit-select instruction,
// we want to unfold masked merge, with canonical pattern of:
// | A | |B|
// ((x ^ y) & m) ^ y
// | D |
// Into:
// (x & m) | (y & ~m)
// If y is a constant, m is not a 'not', and the 'andn' does not work with
// immediates, we unfold into a different pattern:
// ~(~x & m) & (m | y)
// If x is a constant, m is a 'not', and the 'andn' does not work with
// immediates, we unfold into a different pattern:
// (x | ~m) & ~(~m & ~y)
// NOTE: we don't unfold the pattern if 'xor' is actually a 'not', because at
// the very least that breaks andnpd / andnps patterns, and because those
// patterns are simplified in IR and shouldn't be created in the DAG
SDValue DAGCombiner::unfoldMaskedMerge(SDNode *N) {
assert(N->getOpcode() == ISD::XOR);
// Don't touch 'not' (i.e. where y = -1).
if (isAllOnesOrAllOnesSplat(N->getOperand(1)))
return SDValue();
EVT VT = N->getValueType(0);
// There are 3 commutable operators in the pattern,
// so we have to deal with 8 possible variants of the basic pattern.
SDValue X, Y, M;
auto matchAndXor = [&X, &Y, &M](SDValue And, unsigned XorIdx, SDValue Other) {
if (And.getOpcode() != ISD::AND || !And.hasOneUse())
return false;
SDValue Xor = And.getOperand(XorIdx);
if (Xor.getOpcode() != ISD::XOR || !Xor.hasOneUse())
return false;
SDValue Xor0 = Xor.getOperand(0);
SDValue Xor1 = Xor.getOperand(1);
// Don't touch 'not' (i.e. where y = -1).
if (isAllOnesOrAllOnesSplat(Xor1))
return false;
if (Other == Xor0)
std::swap(Xor0, Xor1);
if (Other != Xor1)
return false;
X = Xor0;
Y = Xor1;
M = And.getOperand(XorIdx ? 0 : 1);
return true;
};
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
if (!matchAndXor(N0, 0, N1) && !matchAndXor(N0, 1, N1) &&
!matchAndXor(N1, 0, N0) && !matchAndXor(N1, 1, N0))
return SDValue();
// Don't do anything if the mask is constant. This should not be reachable.
// InstCombine should have already unfolded this pattern, and DAGCombiner
// probably shouldn't produce it, too.
if (isa<ConstantSDNode>(M.getNode()))
return SDValue();
// We can transform if the target has AndNot
if (!TLI.hasAndNot(M))
return SDValue();
SDLoc DL(N);
// If Y is a constant, check that 'andn' works with immediates. Unless M is
// a bitwise not that would already allow ANDN to be used.
if (!TLI.hasAndNot(Y) && !isBitwiseNot(M)) {
assert(TLI.hasAndNot(X) && "Only mask is a variable? Unreachable.");
// If not, we need to do a bit more work to make sure andn is still used.
SDValue NotX = DAG.getNOT(DL, X, VT);
SDValue LHS = DAG.getNode(ISD::AND, DL, VT, NotX, M);
SDValue NotLHS = DAG.getNOT(DL, LHS, VT);
SDValue RHS = DAG.getNode(ISD::OR, DL, VT, M, Y);
return DAG.getNode(ISD::AND, DL, VT, NotLHS, RHS);
}
// If X is a constant and M is a bitwise not, check that 'andn' works with
// immediates.
if (!TLI.hasAndNot(X) && isBitwiseNot(M)) {
assert(TLI.hasAndNot(Y) && "Only mask is a variable? Unreachable.");
// If not, we need to do a bit more work to make sure andn is still used.
SDValue NotM = M.getOperand(0);
SDValue LHS = DAG.getNode(ISD::OR, DL, VT, X, NotM);
SDValue NotY = DAG.getNOT(DL, Y, VT);
SDValue RHS = DAG.getNode(ISD::AND, DL, VT, NotM, NotY);
SDValue NotRHS = DAG.getNOT(DL, RHS, VT);
return DAG.getNode(ISD::AND, DL, VT, LHS, NotRHS);
}
SDValue LHS = DAG.getNode(ISD::AND, DL, VT, X, M);
SDValue NotM = DAG.getNOT(DL, M, VT);
SDValue RHS = DAG.getNode(ISD::AND, DL, VT, Y, NotM);
return DAG.getNode(ISD::OR, DL, VT, LHS, RHS);
}
SDValue DAGCombiner::visitXOR(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N0.getValueType();
SDLoc DL(N);
// fold (xor undef, undef) -> 0. This is a common idiom (misuse).
if (N0.isUndef() && N1.isUndef())
return DAG.getConstant(0, DL, VT);
// fold (xor x, undef) -> undef
if (N0.isUndef())
return N0;
if (N1.isUndef())
return N1;
// fold (xor c1, c2) -> c1^c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::XOR, DL, VT, {N0, N1}))
return C;
// canonicalize constant to RHS
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
!DAG.isConstantIntBuildVectorOrConstantInt(N1))
return DAG.getNode(ISD::XOR, DL, VT, N1, N0);
// fold vector ops
if (VT.isVector()) {
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
// fold (xor x, 0) -> x, vector edition
if (ISD::isConstantSplatVectorAllZeros(N1.getNode()))
return N0;
}
// fold (xor x, 0) -> x
if (isNullConstant(N1))
return N0;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
// reassociate xor
if (SDValue RXOR = reassociateOps(ISD::XOR, DL, N0, N1, N->getFlags()))
return RXOR;
// look for 'add-like' folds:
// XOR(N0,MIN_SIGNED_VALUE) == ADD(N0,MIN_SIGNED_VALUE)
if ((!LegalOperations || TLI.isOperationLegal(ISD::ADD, VT)) &&
isMinSignedConstant(N1))
if (SDValue Combined = visitADDLike(N))
return Combined;
// fold !(x cc y) -> (x !cc y)
unsigned N0Opcode = N0.getOpcode();
SDValue LHS, RHS, CC;
if (TLI.isConstTrueVal(N1) &&
isSetCCEquivalent(N0, LHS, RHS, CC, /*MatchStrict*/ true)) {
ISD::CondCode NotCC = ISD::getSetCCInverse(cast<CondCodeSDNode>(CC)->get(),
LHS.getValueType());
if (!LegalOperations ||
TLI.isCondCodeLegal(NotCC, LHS.getSimpleValueType())) {
switch (N0Opcode) {
default:
llvm_unreachable("Unhandled SetCC Equivalent!");
case ISD::SETCC:
return DAG.getSetCC(SDLoc(N0), VT, LHS, RHS, NotCC);
case ISD::SELECT_CC:
return DAG.getSelectCC(SDLoc(N0), LHS, RHS, N0.getOperand(2),
N0.getOperand(3), NotCC);
case ISD::STRICT_FSETCC:
case ISD::STRICT_FSETCCS: {
if (N0.hasOneUse()) {
// FIXME Can we handle multiple uses? Could we token factor the chain
// results from the new/old setcc?
SDValue SetCC =
DAG.getSetCC(SDLoc(N0), VT, LHS, RHS, NotCC,
N0.getOperand(0), N0Opcode == ISD::STRICT_FSETCCS);
CombineTo(N, SetCC);
DAG.ReplaceAllUsesOfValueWith(N0.getValue(1), SetCC.getValue(1));
recursivelyDeleteUnusedNodes(N0.getNode());
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
break;
}
}
}
}
// fold (not (zext (setcc x, y))) -> (zext (not (setcc x, y)))
if (isOneConstant(N1) && N0Opcode == ISD::ZERO_EXTEND && N0.hasOneUse() &&
isSetCCEquivalent(N0.getOperand(0), LHS, RHS, CC)){
SDValue V = N0.getOperand(0);
SDLoc DL0(N0);
V = DAG.getNode(ISD::XOR, DL0, V.getValueType(), V,
DAG.getConstant(1, DL0, V.getValueType()));
AddToWorklist(V.getNode());
return DAG.getNode(ISD::ZERO_EXTEND, DL, VT, V);
}
// fold (not (or x, y)) -> (and (not x), (not y)) iff x or y are setcc
if (isOneConstant(N1) && VT == MVT::i1 && N0.hasOneUse() &&
(N0Opcode == ISD::OR || N0Opcode == ISD::AND)) {
SDValue N00 = N0.getOperand(0), N01 = N0.getOperand(1);
if (isOneUseSetCC(N01) || isOneUseSetCC(N00)) {
unsigned NewOpcode = N0Opcode == ISD::AND ? ISD::OR : ISD::AND;
N00 = DAG.getNode(ISD::XOR, SDLoc(N00), VT, N00, N1); // N00 = ~N00
N01 = DAG.getNode(ISD::XOR, SDLoc(N01), VT, N01, N1); // N01 = ~N01
AddToWorklist(N00.getNode()); AddToWorklist(N01.getNode());
return DAG.getNode(NewOpcode, DL, VT, N00, N01);
}
}
// fold (not (or x, y)) -> (and (not x), (not y)) iff x or y are constants
if (isAllOnesConstant(N1) && N0.hasOneUse() &&
(N0Opcode == ISD::OR || N0Opcode == ISD::AND)) {
SDValue N00 = N0.getOperand(0), N01 = N0.getOperand(1);
if (isa<ConstantSDNode>(N01) || isa<ConstantSDNode>(N00)) {
unsigned NewOpcode = N0Opcode == ISD::AND ? ISD::OR : ISD::AND;
N00 = DAG.getNode(ISD::XOR, SDLoc(N00), VT, N00, N1); // N00 = ~N00
N01 = DAG.getNode(ISD::XOR, SDLoc(N01), VT, N01, N1); // N01 = ~N01
AddToWorklist(N00.getNode()); AddToWorklist(N01.getNode());
return DAG.getNode(NewOpcode, DL, VT, N00, N01);
}
}
// fold (not (neg x)) -> (add X, -1)
// FIXME: This can be generalized to (not (sub Y, X)) -> (add X, ~Y) if
// Y is a constant or the subtract has a single use.
if (isAllOnesConstant(N1) && N0.getOpcode() == ISD::SUB &&
isNullConstant(N0.getOperand(0))) {
return DAG.getNode(ISD::ADD, DL, VT, N0.getOperand(1),
DAG.getAllOnesConstant(DL, VT));
}
// fold (not (add X, -1)) -> (neg X)
if (isAllOnesConstant(N1) && N0.getOpcode() == ISD::ADD &&
isAllOnesOrAllOnesSplat(N0.getOperand(1))) {
return DAG.getNode(ISD::SUB, DL, VT, DAG.getConstant(0, DL, VT),
N0.getOperand(0));
}
// fold (xor (and x, y), y) -> (and (not x), y)
if (N0Opcode == ISD::AND && N0.hasOneUse() && N0->getOperand(1) == N1) {
SDValue X = N0.getOperand(0);
SDValue NotX = DAG.getNOT(SDLoc(X), X, VT);
AddToWorklist(NotX.getNode());
return DAG.getNode(ISD::AND, DL, VT, NotX, N1);
}
if ((N0Opcode == ISD::SRL || N0Opcode == ISD::SHL) && N0.hasOneUse()) {
ConstantSDNode *XorC = isConstOrConstSplat(N1);
ConstantSDNode *ShiftC = isConstOrConstSplat(N0.getOperand(1));
unsigned BitWidth = VT.getScalarSizeInBits();
if (XorC && ShiftC) {
// Don't crash on an oversized shift. We can not guarantee that a bogus
// shift has been simplified to undef.
uint64_t ShiftAmt = ShiftC->getLimitedValue();
if (ShiftAmt < BitWidth) {
APInt Ones = APInt::getAllOnes(BitWidth);
Ones = N0Opcode == ISD::SHL ? Ones.shl(ShiftAmt) : Ones.lshr(ShiftAmt);
if (XorC->getAPIntValue() == Ones) {
// If the xor constant is a shifted -1, do a 'not' before the shift:
// xor (X << ShiftC), XorC --> (not X) << ShiftC
// xor (X >> ShiftC), XorC --> (not X) >> ShiftC
SDValue Not = DAG.getNOT(DL, N0.getOperand(0), VT);
return DAG.getNode(N0Opcode, DL, VT, Not, N0.getOperand(1));
}
}
}
}
// fold Y = sra (X, size(X)-1); xor (add (X, Y), Y) -> (abs X)
if (TLI.isOperationLegalOrCustom(ISD::ABS, VT)) {
SDValue A = N0Opcode == ISD::ADD ? N0 : N1;
SDValue S = N0Opcode == ISD::SRA ? N0 : N1;
if (A.getOpcode() == ISD::ADD && S.getOpcode() == ISD::SRA) {
SDValue A0 = A.getOperand(0), A1 = A.getOperand(1);
SDValue S0 = S.getOperand(0);
if ((A0 == S && A1 == S0) || (A1 == S && A0 == S0))
if (ConstantSDNode *C = isConstOrConstSplat(S.getOperand(1)))
if (C->getAPIntValue() == (VT.getScalarSizeInBits() - 1))
return DAG.getNode(ISD::ABS, DL, VT, S0);
}
}
// fold (xor x, x) -> 0
if (N0 == N1)
return tryFoldToZero(DL, TLI, VT, DAG, LegalOperations);
// fold (xor (shl 1, x), -1) -> (rotl ~1, x)
// Here is a concrete example of this equivalence:
// i16 x == 14
// i16 shl == 1 << 14 == 16384 == 0b0100000000000000
// i16 xor == ~(1 << 14) == 49151 == 0b1011111111111111
//
// =>
//
// i16 ~1 == 0b1111111111111110
// i16 rol(~1, 14) == 0b1011111111111111
//
// Some additional tips to help conceptualize this transform:
// - Try to see the operation as placing a single zero in a value of all ones.
// - There exists no value for x which would allow the result to contain zero.
// - Values of x larger than the bitwidth are undefined and do not require a
// consistent result.
// - Pushing the zero left requires shifting one bits in from the right.
// A rotate left of ~1 is a nice way of achieving the desired result.
if (TLI.isOperationLegalOrCustom(ISD::ROTL, VT) && N0Opcode == ISD::SHL &&
isAllOnesConstant(N1) && isOneConstant(N0.getOperand(0))) {
return DAG.getNode(ISD::ROTL, DL, VT, DAG.getConstant(~1, DL, VT),
N0.getOperand(1));
}
// Simplify: xor (op x...), (op y...) -> (op (xor x, y))
if (N0Opcode == N1.getOpcode())
if (SDValue V = hoistLogicOpWithSameOpcodeHands(N))
return V;
if (SDValue R = foldLogicOfShifts(N, N0, N1, DAG))
return R;
if (SDValue R = foldLogicOfShifts(N, N1, N0, DAG))
return R;
// Unfold ((x ^ y) & m) ^ y into (x & m) | (y & ~m) if profitable
if (SDValue MM = unfoldMaskedMerge(N))
return MM;
// Simplify the expression using non-local knowledge.
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
if (SDValue Combined = combineCarryDiamond(DAG, TLI, N0, N1, N))
return Combined;
return SDValue();
}
/// If we have a shift-by-constant of a bitwise logic op that itself has a
/// shift-by-constant operand with identical opcode, we may be able to convert
/// that into 2 independent shifts followed by the logic op. This is a
/// throughput improvement.
static SDValue combineShiftOfShiftedLogic(SDNode *Shift, SelectionDAG &DAG) {
// Match a one-use bitwise logic op.
SDValue LogicOp = Shift->getOperand(0);
if (!LogicOp.hasOneUse())
return SDValue();
unsigned LogicOpcode = LogicOp.getOpcode();
if (LogicOpcode != ISD::AND && LogicOpcode != ISD::OR &&
LogicOpcode != ISD::XOR)
return SDValue();
// Find a matching one-use shift by constant.
unsigned ShiftOpcode = Shift->getOpcode();
SDValue C1 = Shift->getOperand(1);
ConstantSDNode *C1Node = isConstOrConstSplat(C1);
assert(C1Node && "Expected a shift with constant operand");
const APInt &C1Val = C1Node->getAPIntValue();
auto matchFirstShift = [&](SDValue V, SDValue &ShiftOp,
const APInt *&ShiftAmtVal) {
if (V.getOpcode() != ShiftOpcode || !V.hasOneUse())
return false;
ConstantSDNode *ShiftCNode = isConstOrConstSplat(V.getOperand(1));
if (!ShiftCNode)
return false;
// Capture the shifted operand and shift amount value.
ShiftOp = V.getOperand(0);
ShiftAmtVal = &ShiftCNode->getAPIntValue();
// Shift amount types do not have to match their operand type, so check that
// the constants are the same width.
if (ShiftAmtVal->getBitWidth() != C1Val.getBitWidth())
return false;
// The fold is not valid if the sum of the shift values exceeds bitwidth.
if ((*ShiftAmtVal + C1Val).uge(V.getScalarValueSizeInBits()))
return false;
return true;
};
// Logic ops are commutative, so check each operand for a match.
SDValue X, Y;
const APInt *C0Val;
if (matchFirstShift(LogicOp.getOperand(0), X, C0Val))
Y = LogicOp.getOperand(1);
else if (matchFirstShift(LogicOp.getOperand(1), X, C0Val))
Y = LogicOp.getOperand(0);
else
return SDValue();
// shift (logic (shift X, C0), Y), C1 -> logic (shift X, C0+C1), (shift Y, C1)
SDLoc DL(Shift);
EVT VT = Shift->getValueType(0);
EVT ShiftAmtVT = Shift->getOperand(1).getValueType();
SDValue ShiftSumC = DAG.getConstant(*C0Val + C1Val, DL, ShiftAmtVT);
SDValue NewShift1 = DAG.getNode(ShiftOpcode, DL, VT, X, ShiftSumC);
SDValue NewShift2 = DAG.getNode(ShiftOpcode, DL, VT, Y, C1);
return DAG.getNode(LogicOpcode, DL, VT, NewShift1, NewShift2);
}
/// Handle transforms common to the three shifts, when the shift amount is a
/// constant.
/// We are looking for: (shift being one of shl/sra/srl)
/// shift (binop X, C0), C1
/// And want to transform into:
/// binop (shift X, C1), (shift C0, C1)
SDValue DAGCombiner::visitShiftByConstant(SDNode *N) {
assert(isConstOrConstSplat(N->getOperand(1)) && "Expected constant operand");
// Do not turn a 'not' into a regular xor.
if (isBitwiseNot(N->getOperand(0)))
return SDValue();
// The inner binop must be one-use, since we want to replace it.
SDValue LHS = N->getOperand(0);
if (!LHS.hasOneUse() || !TLI.isDesirableToCommuteWithShift(N, Level))
return SDValue();
// TODO: This is limited to early combining because it may reveal regressions
// otherwise. But since we just checked a target hook to see if this is
// desirable, that should have filtered out cases where this interferes
// with some other pattern matching.
if (!LegalTypes)
if (SDValue R = combineShiftOfShiftedLogic(N, DAG))
return R;
// We want to pull some binops through shifts, so that we have (and (shift))
// instead of (shift (and)), likewise for add, or, xor, etc. This sort of
// thing happens with address calculations, so it's important to canonicalize
// it.
switch (LHS.getOpcode()) {
default:
return SDValue();
case ISD::OR:
case ISD::XOR:
case ISD::AND:
break;
case ISD::ADD:
if (N->getOpcode() != ISD::SHL)
return SDValue(); // only shl(add) not sr[al](add).
break;
}
// We require the RHS of the binop to be a constant and not opaque as well.
ConstantSDNode *BinOpCst = getAsNonOpaqueConstant(LHS.getOperand(1));
if (!BinOpCst)
return SDValue();
// FIXME: disable this unless the input to the binop is a shift by a constant
// or is copy/select. Enable this in other cases when figure out it's exactly
// profitable.
SDValue BinOpLHSVal = LHS.getOperand(0);
bool IsShiftByConstant = (BinOpLHSVal.getOpcode() == ISD::SHL ||
BinOpLHSVal.getOpcode() == ISD::SRA ||
BinOpLHSVal.getOpcode() == ISD::SRL) &&
isa<ConstantSDNode>(BinOpLHSVal.getOperand(1));
bool IsCopyOrSelect = BinOpLHSVal.getOpcode() == ISD::CopyFromReg ||
BinOpLHSVal.getOpcode() == ISD::SELECT;
if (!IsShiftByConstant && !IsCopyOrSelect)
return SDValue();
if (IsCopyOrSelect && N->hasOneUse())
return SDValue();
// Fold the constants, shifting the binop RHS by the shift amount.
SDLoc DL(N);
EVT VT = N->getValueType(0);
SDValue NewRHS = DAG.getNode(N->getOpcode(), DL, VT, LHS.getOperand(1),
N->getOperand(1));
assert(isa<ConstantSDNode>(NewRHS) && "Folding was not successful!");
SDValue NewShift = DAG.getNode(N->getOpcode(), DL, VT, LHS.getOperand(0),
N->getOperand(1));
return DAG.getNode(LHS.getOpcode(), DL, VT, NewShift, NewRHS);
}
SDValue DAGCombiner::distributeTruncateThroughAnd(SDNode *N) {
assert(N->getOpcode() == ISD::TRUNCATE);
assert(N->getOperand(0).getOpcode() == ISD::AND);
// (truncate:TruncVT (and N00, N01C)) -> (and (truncate:TruncVT N00), TruncC)
EVT TruncVT = N->getValueType(0);
if (N->hasOneUse() && N->getOperand(0).hasOneUse() &&
TLI.isTypeDesirableForOp(ISD::AND, TruncVT)) {
SDValue N01 = N->getOperand(0).getOperand(1);
if (isConstantOrConstantVector(N01, /* NoOpaques */ true)) {
SDLoc DL(N);
SDValue N00 = N->getOperand(0).getOperand(0);
SDValue Trunc00 = DAG.getNode(ISD::TRUNCATE, DL, TruncVT, N00);
SDValue Trunc01 = DAG.getNode(ISD::TRUNCATE, DL, TruncVT, N01);
AddToWorklist(Trunc00.getNode());
AddToWorklist(Trunc01.getNode());
return DAG.getNode(ISD::AND, DL, TruncVT, Trunc00, Trunc01);
}
}
return SDValue();
}
SDValue DAGCombiner::visitRotate(SDNode *N) {
SDLoc dl(N);
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
unsigned Bitsize = VT.getScalarSizeInBits();
// fold (rot x, 0) -> x
if (isNullOrNullSplat(N1))
return N0;
// fold (rot x, c) -> x iff (c % BitSize) == 0
if (isPowerOf2_32(Bitsize) && Bitsize > 1) {
APInt ModuloMask(N1.getScalarValueSizeInBits(), Bitsize - 1);
if (DAG.MaskedValueIsZero(N1, ModuloMask))
return N0;
}
// fold (rot x, c) -> (rot x, c % BitSize)
bool OutOfRange = false;
auto MatchOutOfRange = [Bitsize, &OutOfRange](ConstantSDNode *C) {
OutOfRange |= C->getAPIntValue().uge(Bitsize);
return true;
};
if (ISD::matchUnaryPredicate(N1, MatchOutOfRange) && OutOfRange) {
EVT AmtVT = N1.getValueType();
SDValue Bits = DAG.getConstant(Bitsize, dl, AmtVT);
if (SDValue Amt =
DAG.FoldConstantArithmetic(ISD::UREM, dl, AmtVT, {N1, Bits}))
return DAG.getNode(N->getOpcode(), dl, VT, N0, Amt);
}
// rot i16 X, 8 --> bswap X
auto *RotAmtC = isConstOrConstSplat(N1);
if (RotAmtC && RotAmtC->getAPIntValue() == 8 &&
VT.getScalarSizeInBits() == 16 && hasOperation(ISD::BSWAP, VT))
return DAG.getNode(ISD::BSWAP, dl, VT, N0);
// Simplify the operands using demanded-bits information.
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
// fold (rot* x, (trunc (and y, c))) -> (rot* x, (and (trunc y), (trunc c))).
if (N1.getOpcode() == ISD::TRUNCATE &&
N1.getOperand(0).getOpcode() == ISD::AND) {
if (SDValue NewOp1 = distributeTruncateThroughAnd(N1.getNode()))
return DAG.getNode(N->getOpcode(), dl, VT, N0, NewOp1);
}
unsigned NextOp = N0.getOpcode();
// fold (rot* (rot* x, c2), c1)
// -> (rot* x, ((c1 % bitsize) +- (c2 % bitsize)) % bitsize)
if (NextOp == ISD::ROTL || NextOp == ISD::ROTR) {
SDNode *C1 = DAG.isConstantIntBuildVectorOrConstantInt(N1);
SDNode *C2 = DAG.isConstantIntBuildVectorOrConstantInt(N0.getOperand(1));
if (C1 && C2 && C1->getValueType(0) == C2->getValueType(0)) {
EVT ShiftVT = C1->getValueType(0);
bool SameSide = (N->getOpcode() == NextOp);
unsigned CombineOp = SameSide ? ISD::ADD : ISD::SUB;
SDValue BitsizeC = DAG.getConstant(Bitsize, dl, ShiftVT);
SDValue Norm1 = DAG.FoldConstantArithmetic(ISD::UREM, dl, ShiftVT,
{N1, BitsizeC});
SDValue Norm2 = DAG.FoldConstantArithmetic(ISD::UREM, dl, ShiftVT,
{N0.getOperand(1), BitsizeC});
if (Norm1 && Norm2)
if (SDValue CombinedShift = DAG.FoldConstantArithmetic(
CombineOp, dl, ShiftVT, {Norm1, Norm2})) {
SDValue CombinedShiftNorm = DAG.FoldConstantArithmetic(
ISD::UREM, dl, ShiftVT, {CombinedShift, BitsizeC});
return DAG.getNode(N->getOpcode(), dl, VT, N0->getOperand(0),
CombinedShiftNorm);
}
}
}
return SDValue();
}
SDValue DAGCombiner::visitSHL(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
if (SDValue V = DAG.simplifyShift(N0, N1))
return V;
EVT VT = N0.getValueType();
EVT ShiftVT = N1.getValueType();
unsigned OpSizeInBits = VT.getScalarSizeInBits();
// fold (shl c1, c2) -> c1<<c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::SHL, SDLoc(N), VT, {N0, N1}))
return C;
// fold vector ops
if (VT.isVector()) {
if (SDValue FoldedVOp = SimplifyVBinOp(N, SDLoc(N)))
return FoldedVOp;
BuildVectorSDNode *N1CV = dyn_cast<BuildVectorSDNode>(N1);
// If setcc produces all-one true value then:
// (shl (and (setcc) N01CV) N1CV) -> (and (setcc) N01CV<<N1CV)
if (N1CV && N1CV->isConstant()) {
if (N0.getOpcode() == ISD::AND) {
SDValue N00 = N0->getOperand(0);
SDValue N01 = N0->getOperand(1);
BuildVectorSDNode *N01CV = dyn_cast<BuildVectorSDNode>(N01);
if (N01CV && N01CV->isConstant() && N00.getOpcode() == ISD::SETCC &&
TLI.getBooleanContents(N00.getOperand(0).getValueType()) ==
TargetLowering::ZeroOrNegativeOneBooleanContent) {
if (SDValue C =
DAG.FoldConstantArithmetic(ISD::SHL, SDLoc(N), VT, {N01, N1}))
return DAG.getNode(ISD::AND, SDLoc(N), VT, N00, C);
}
}
}
}
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
// if (shl x, c) is known to be zero, return 0
if (DAG.MaskedValueIsZero(SDValue(N, 0), APInt::getAllOnes(OpSizeInBits)))
return DAG.getConstant(0, SDLoc(N), VT);
// fold (shl x, (trunc (and y, c))) -> (shl x, (and (trunc y), (trunc c))).
if (N1.getOpcode() == ISD::TRUNCATE &&
N1.getOperand(0).getOpcode() == ISD::AND) {
if (SDValue NewOp1 = distributeTruncateThroughAnd(N1.getNode()))
return DAG.getNode(ISD::SHL, SDLoc(N), VT, N0, NewOp1);
}
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
// fold (shl (shl x, c1), c2) -> 0 or (shl x, (add c1, c2))
if (N0.getOpcode() == ISD::SHL) {
auto MatchOutOfRange = [OpSizeInBits](ConstantSDNode *LHS,
ConstantSDNode *RHS) {
APInt c1 = LHS->getAPIntValue();
APInt c2 = RHS->getAPIntValue();
zeroExtendToMatch(c1, c2, 1 /* Overflow Bit */);
return (c1 + c2).uge(OpSizeInBits);
};
if (ISD::matchBinaryPredicate(N1, N0.getOperand(1), MatchOutOfRange))
return DAG.getConstant(0, SDLoc(N), VT);
auto MatchInRange = [OpSizeInBits](ConstantSDNode *LHS,
ConstantSDNode *RHS) {
APInt c1 = LHS->getAPIntValue();
APInt c2 = RHS->getAPIntValue();
zeroExtendToMatch(c1, c2, 1 /* Overflow Bit */);
return (c1 + c2).ult(OpSizeInBits);
};
if (ISD::matchBinaryPredicate(N1, N0.getOperand(1), MatchInRange)) {
SDLoc DL(N);
SDValue Sum = DAG.getNode(ISD::ADD, DL, ShiftVT, N1, N0.getOperand(1));
return DAG.getNode(ISD::SHL, DL, VT, N0.getOperand(0), Sum);
}
}
// fold (shl (ext (shl x, c1)), c2) -> (shl (ext x), (add c1, c2))
// For this to be valid, the second form must not preserve any of the bits
// that are shifted out by the inner shift in the first form. This means
// the outer shift size must be >= the number of bits added by the ext.
// As a corollary, we don't care what kind of ext it is.
if ((N0.getOpcode() == ISD::ZERO_EXTEND ||
N0.getOpcode() == ISD::ANY_EXTEND ||
N0.getOpcode() == ISD::SIGN_EXTEND) &&
N0.getOperand(0).getOpcode() == ISD::SHL) {
SDValue N0Op0 = N0.getOperand(0);
SDValue InnerShiftAmt = N0Op0.getOperand(1);
EVT InnerVT = N0Op0.getValueType();
uint64_t InnerBitwidth = InnerVT.getScalarSizeInBits();
auto MatchOutOfRange = [OpSizeInBits, InnerBitwidth](ConstantSDNode *LHS,
ConstantSDNode *RHS) {
APInt c1 = LHS->getAPIntValue();
APInt c2 = RHS->getAPIntValue();
zeroExtendToMatch(c1, c2, 1 /* Overflow Bit */);
return c2.uge(OpSizeInBits - InnerBitwidth) &&
(c1 + c2).uge(OpSizeInBits);
};
if (ISD::matchBinaryPredicate(InnerShiftAmt, N1, MatchOutOfRange,
/*AllowUndefs*/ false,
/*AllowTypeMismatch*/ true))
return DAG.getConstant(0, SDLoc(N), VT);
auto MatchInRange = [OpSizeInBits, InnerBitwidth](ConstantSDNode *LHS,
ConstantSDNode *RHS) {
APInt c1 = LHS->getAPIntValue();
APInt c2 = RHS->getAPIntValue();
zeroExtendToMatch(c1, c2, 1 /* Overflow Bit */);
return c2.uge(OpSizeInBits - InnerBitwidth) &&
(c1 + c2).ult(OpSizeInBits);
};
if (ISD::matchBinaryPredicate(InnerShiftAmt, N1, MatchInRange,
/*AllowUndefs*/ false,
/*AllowTypeMismatch*/ true)) {
SDLoc DL(N);
SDValue Ext = DAG.getNode(N0.getOpcode(), DL, VT, N0Op0.getOperand(0));
SDValue Sum = DAG.getZExtOrTrunc(InnerShiftAmt, DL, ShiftVT);
Sum = DAG.getNode(ISD::ADD, DL, ShiftVT, Sum, N1);
return DAG.getNode(ISD::SHL, DL, VT, Ext, Sum);
}
}
// fold (shl (zext (srl x, C)), C) -> (zext (shl (srl x, C), C))
// Only fold this if the inner zext has no other uses to avoid increasing
// the total number of instructions.
if (N0.getOpcode() == ISD::ZERO_EXTEND && N0.hasOneUse() &&
N0.getOperand(0).getOpcode() == ISD::SRL) {
SDValue N0Op0 = N0.getOperand(0);
SDValue InnerShiftAmt = N0Op0.getOperand(1);
auto MatchEqual = [VT](ConstantSDNode *LHS, ConstantSDNode *RHS) {
APInt c1 = LHS->getAPIntValue();
APInt c2 = RHS->getAPIntValue();
zeroExtendToMatch(c1, c2);
return c1.ult(VT.getScalarSizeInBits()) && (c1 == c2);
};
if (ISD::matchBinaryPredicate(InnerShiftAmt, N1, MatchEqual,
/*AllowUndefs*/ false,
/*AllowTypeMismatch*/ true)) {
SDLoc DL(N);
EVT InnerShiftAmtVT = N0Op0.getOperand(1).getValueType();
SDValue NewSHL = DAG.getZExtOrTrunc(N1, DL, InnerShiftAmtVT);
NewSHL = DAG.getNode(ISD::SHL, DL, N0Op0.getValueType(), N0Op0, NewSHL);
AddToWorklist(NewSHL.getNode());
return DAG.getNode(ISD::ZERO_EXTEND, SDLoc(N0), VT, NewSHL);
}
}
if (N0.getOpcode() == ISD::SRL || N0.getOpcode() == ISD::SRA) {
auto MatchShiftAmount = [OpSizeInBits](ConstantSDNode *LHS,
ConstantSDNode *RHS) {
const APInt &LHSC = LHS->getAPIntValue();
const APInt &RHSC = RHS->getAPIntValue();
return LHSC.ult(OpSizeInBits) && RHSC.ult(OpSizeInBits) &&
LHSC.getZExtValue() <= RHSC.getZExtValue();
};
SDLoc DL(N);
// fold (shl (sr[la] exact X, C1), C2) -> (shl X, (C2-C1)) if C1 <= C2
// fold (shl (sr[la] exact X, C1), C2) -> (sr[la] X, (C2-C1)) if C1 >= C2
if (N0->getFlags().hasExact()) {
if (ISD::matchBinaryPredicate(N0.getOperand(1), N1, MatchShiftAmount,
/*AllowUndefs*/ false,
/*AllowTypeMismatch*/ true)) {
SDValue N01 = DAG.getZExtOrTrunc(N0.getOperand(1), DL, ShiftVT);
SDValue Diff = DAG.getNode(ISD::SUB, DL, ShiftVT, N1, N01);
return DAG.getNode(ISD::SHL, DL, VT, N0.getOperand(0), Diff);
}
if (ISD::matchBinaryPredicate(N1, N0.getOperand(1), MatchShiftAmount,
/*AllowUndefs*/ false,
/*AllowTypeMismatch*/ true)) {
SDValue N01 = DAG.getZExtOrTrunc(N0.getOperand(1), DL, ShiftVT);
SDValue Diff = DAG.getNode(ISD::SUB, DL, ShiftVT, N01, N1);
return DAG.getNode(N0.getOpcode(), DL, VT, N0.getOperand(0), Diff);
}
}
// fold (shl (srl x, c1), c2) -> (and (shl x, (sub c2, c1), MASK) or
// (and (srl x, (sub c1, c2), MASK)
// Only fold this if the inner shift has no other uses -- if it does,
// folding this will increase the total number of instructions.
if (N0.getOpcode() == ISD::SRL &&
(N0.getOperand(1) == N1 || N0.hasOneUse()) &&
TLI.shouldFoldConstantShiftPairToMask(N, Level)) {
if (ISD::matchBinaryPredicate(N1, N0.getOperand(1), MatchShiftAmount,
/*AllowUndefs*/ false,
/*AllowTypeMismatch*/ true)) {
SDValue N01 = DAG.getZExtOrTrunc(N0.getOperand(1), DL, ShiftVT);
SDValue Diff = DAG.getNode(ISD::SUB, DL, ShiftVT, N01, N1);
SDValue Mask = DAG.getAllOnesConstant(DL, VT);
Mask = DAG.getNode(ISD::SHL, DL, VT, Mask, N01);
Mask = DAG.getNode(ISD::SRL, DL, VT, Mask, Diff);
SDValue Shift = DAG.getNode(ISD::SRL, DL, VT, N0.getOperand(0), Diff);
return DAG.getNode(ISD::AND, DL, VT, Shift, Mask);
}
if (ISD::matchBinaryPredicate(N0.getOperand(1), N1, MatchShiftAmount,
/*AllowUndefs*/ false,
/*AllowTypeMismatch*/ true)) {
SDValue N01 = DAG.getZExtOrTrunc(N0.getOperand(1), DL, ShiftVT);
SDValue Diff = DAG.getNode(ISD::SUB, DL, ShiftVT, N1, N01);
SDValue Mask = DAG.getAllOnesConstant(DL, VT);
Mask = DAG.getNode(ISD::SHL, DL, VT, Mask, N1);
SDValue Shift = DAG.getNode(ISD::SHL, DL, VT, N0.getOperand(0), Diff);
return DAG.getNode(ISD::AND, DL, VT, Shift, Mask);
}
}
}
// fold (shl (sra x, c1), c1) -> (and x, (shl -1, c1))
if (N0.getOpcode() == ISD::SRA && N1 == N0.getOperand(1) &&
isConstantOrConstantVector(N1, /* No Opaques */ true)) {
SDLoc DL(N);
SDValue AllBits = DAG.getAllOnesConstant(DL, VT);
SDValue HiBitsMask = DAG.getNode(ISD::SHL, DL, VT, AllBits, N1);
return DAG.getNode(ISD::AND, DL, VT, N0.getOperand(0), HiBitsMask);
}
// fold (shl (add x, c1), c2) -> (add (shl x, c2), c1 << c2)
// fold (shl (or x, c1), c2) -> (or (shl x, c2), c1 << c2)
// Variant of version done on multiply, except mul by a power of 2 is turned
// into a shift.
if ((N0.getOpcode() == ISD::ADD || N0.getOpcode() == ISD::OR) &&
N0->hasOneUse() &&
isConstantOrConstantVector(N1, /* No Opaques */ true) &&
isConstantOrConstantVector(N0.getOperand(1), /* No Opaques */ true) &&
TLI.isDesirableToCommuteWithShift(N, Level)) {
SDValue Shl0 = DAG.getNode(ISD::SHL, SDLoc(N0), VT, N0.getOperand(0), N1);
SDValue Shl1 = DAG.getNode(ISD::SHL, SDLoc(N1), VT, N0.getOperand(1), N1);
AddToWorklist(Shl0.getNode());
AddToWorklist(Shl1.getNode());
return DAG.getNode(N0.getOpcode(), SDLoc(N), VT, Shl0, Shl1);
}
// fold (shl (mul x, c1), c2) -> (mul x, c1 << c2)
if (N0.getOpcode() == ISD::MUL && N0->hasOneUse()) {
SDValue N01 = N0.getOperand(1);
if (SDValue Shl =
DAG.FoldConstantArithmetic(ISD::SHL, SDLoc(N1), VT, {N01, N1}))
return DAG.getNode(ISD::MUL, SDLoc(N), VT, N0.getOperand(0), Shl);
}
ConstantSDNode *N1C = isConstOrConstSplat(N1);
if (N1C && !N1C->isOpaque())
if (SDValue NewSHL = visitShiftByConstant(N))
return NewSHL;
// Fold (shl (vscale * C0), C1) to (vscale * (C0 << C1)).
if (N0.getOpcode() == ISD::VSCALE)
if (ConstantSDNode *NC1 = isConstOrConstSplat(N->getOperand(1))) {
const APInt &C0 = N0.getConstantOperandAPInt(0);
const APInt &C1 = NC1->getAPIntValue();
return DAG.getVScale(SDLoc(N), VT, C0 << C1);
}
// Fold (shl step_vector(C0), C1) to (step_vector(C0 << C1)).
APInt ShlVal;
if (N0.getOpcode() == ISD::STEP_VECTOR)
if (ISD::isConstantSplatVector(N1.getNode(), ShlVal)) {
const APInt &C0 = N0.getConstantOperandAPInt(0);
if (ShlVal.ult(C0.getBitWidth())) {
APInt NewStep = C0 << ShlVal;
return DAG.getStepVector(SDLoc(N), VT, NewStep);
}
}
return SDValue();
}
// Transform a right shift of a multiply into a multiply-high.
// Examples:
// (srl (mul (zext i32:$a to i64), (zext i32:$a to i64)), 32) -> (mulhu $a, $b)
// (sra (mul (sext i32:$a to i64), (sext i32:$a to i64)), 32) -> (mulhs $a, $b)
static SDValue combineShiftToMULH(SDNode *N, SelectionDAG &DAG,
const TargetLowering &TLI) {
assert((N->getOpcode() == ISD::SRL || N->getOpcode() == ISD::SRA) &&
"SRL or SRA node is required here!");
// Check the shift amount. Proceed with the transformation if the shift
// amount is constant.
ConstantSDNode *ShiftAmtSrc = isConstOrConstSplat(N->getOperand(1));
if (!ShiftAmtSrc)
return SDValue();
SDLoc DL(N);
// The operation feeding into the shift must be a multiply.
SDValue ShiftOperand = N->getOperand(0);
if (ShiftOperand.getOpcode() != ISD::MUL)
return SDValue();
// Both operands must be equivalent extend nodes.
SDValue LeftOp = ShiftOperand.getOperand(0);
SDValue RightOp = ShiftOperand.getOperand(1);
bool IsSignExt = LeftOp.getOpcode() == ISD::SIGN_EXTEND;
bool IsZeroExt = LeftOp.getOpcode() == ISD::ZERO_EXTEND;
if (!IsSignExt && !IsZeroExt)
return SDValue();
EVT NarrowVT = LeftOp.getOperand(0).getValueType();
unsigned NarrowVTSize = NarrowVT.getScalarSizeInBits();
SDValue MulhRightOp;
if (ConstantSDNode *Constant = isConstOrConstSplat(RightOp)) {
unsigned ActiveBits = IsSignExt
? Constant->getAPIntValue().getMinSignedBits()
: Constant->getAPIntValue().getActiveBits();
if (ActiveBits > NarrowVTSize)
return SDValue();
MulhRightOp = DAG.getConstant(
Constant->getAPIntValue().trunc(NarrowVT.getScalarSizeInBits()), DL,
NarrowVT);
} else {
if (LeftOp.getOpcode() != RightOp.getOpcode())
return SDValue();
// Check that the two extend nodes are the same type.
if (NarrowVT != RightOp.getOperand(0).getValueType())
return SDValue();
MulhRightOp = RightOp.getOperand(0);
}
EVT WideVT = LeftOp.getValueType();
// Proceed with the transformation if the wide types match.
assert((WideVT == RightOp.getValueType()) &&
"Cannot have a multiply node with two different operand types.");
// Proceed with the transformation if the wide type is twice as large
// as the narrow type.
if (WideVT.getScalarSizeInBits() != 2 * NarrowVTSize)
return SDValue();
// Check the shift amount with the narrow type size.
// Proceed with the transformation if the shift amount is the width
// of the narrow type.
unsigned ShiftAmt = ShiftAmtSrc->getZExtValue();
if (ShiftAmt != NarrowVTSize)
return SDValue();
// If the operation feeding into the MUL is a sign extend (sext),
// we use mulhs. Othewise, zero extends (zext) use mulhu.
unsigned MulhOpcode = IsSignExt ? ISD::MULHS : ISD::MULHU;
// Combine to mulh if mulh is legal/custom for the narrow type on the target.
if (!TLI.isOperationLegalOrCustom(MulhOpcode, NarrowVT))
return SDValue();
SDValue Result =
DAG.getNode(MulhOpcode, DL, NarrowVT, LeftOp.getOperand(0), MulhRightOp);
return (N->getOpcode() == ISD::SRA ? DAG.getSExtOrTrunc(Result, DL, WideVT)
: DAG.getZExtOrTrunc(Result, DL, WideVT));
}
SDValue DAGCombiner::visitSRA(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
if (SDValue V = DAG.simplifyShift(N0, N1))
return V;
EVT VT = N0.getValueType();
unsigned OpSizeInBits = VT.getScalarSizeInBits();
// fold (sra c1, c2) -> (sra c1, c2)
if (SDValue C = DAG.FoldConstantArithmetic(ISD::SRA, SDLoc(N), VT, {N0, N1}))
return C;
// Arithmetic shifting an all-sign-bit value is a no-op.
// fold (sra 0, x) -> 0
// fold (sra -1, x) -> -1
if (DAG.ComputeNumSignBits(N0) == OpSizeInBits)
return N0;
// fold vector ops
if (VT.isVector())
if (SDValue FoldedVOp = SimplifyVBinOp(N, SDLoc(N)))
return FoldedVOp;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
// fold (sra (shl x, c1), c1) -> sext_inreg for some c1 and target supports
// sext_inreg.
ConstantSDNode *N1C = isConstOrConstSplat(N1);
if (N1C && N0.getOpcode() == ISD::SHL && N1 == N0.getOperand(1)) {
unsigned LowBits = OpSizeInBits - (unsigned)N1C->getZExtValue();
EVT ExtVT = EVT::getIntegerVT(*DAG.getContext(), LowBits);
if (VT.isVector())
ExtVT = EVT::getVectorVT(*DAG.getContext(), ExtVT,
VT.getVectorElementCount());
if (!LegalOperations ||
TLI.getOperationAction(ISD::SIGN_EXTEND_INREG, ExtVT) ==
TargetLowering::Legal)
return DAG.getNode(ISD::SIGN_EXTEND_INREG, SDLoc(N), VT,
N0.getOperand(0), DAG.getValueType(ExtVT));
// Even if we can't convert to sext_inreg, we might be able to remove
// this shift pair if the input is already sign extended.
if (DAG.ComputeNumSignBits(N0.getOperand(0)) > N1C->getZExtValue())
return N0.getOperand(0);
}
// fold (sra (sra x, c1), c2) -> (sra x, (add c1, c2))
// clamp (add c1, c2) to max shift.
if (N0.getOpcode() == ISD::SRA) {
SDLoc DL(N);
EVT ShiftVT = N1.getValueType();
EVT ShiftSVT = ShiftVT.getScalarType();
SmallVector<SDValue, 16> ShiftValues;
auto SumOfShifts = [&](ConstantSDNode *LHS, ConstantSDNode *RHS) {
APInt c1 = LHS->getAPIntValue();
APInt c2 = RHS->getAPIntValue();
zeroExtendToMatch(c1, c2, 1 /* Overflow Bit */);
APInt Sum = c1 + c2;
unsigned ShiftSum =
Sum.uge(OpSizeInBits) ? (OpSizeInBits - 1) : Sum.getZExtValue();
ShiftValues.push_back(DAG.getConstant(ShiftSum, DL, ShiftSVT));
return true;
};
if (ISD::matchBinaryPredicate(N1, N0.getOperand(1), SumOfShifts)) {
SDValue ShiftValue;
if (N1.getOpcode() == ISD::BUILD_VECTOR)
ShiftValue = DAG.getBuildVector(ShiftVT, DL, ShiftValues);
else if (N1.getOpcode() == ISD::SPLAT_VECTOR) {
assert(ShiftValues.size() == 1 &&
"Expected matchBinaryPredicate to return one element for "
"SPLAT_VECTORs");
ShiftValue = DAG.getSplatVector(ShiftVT, DL, ShiftValues[0]);
} else
ShiftValue = ShiftValues[0];
return DAG.getNode(ISD::SRA, DL, VT, N0.getOperand(0), ShiftValue);
}
}
// fold (sra (shl X, m), (sub result_size, n))
// -> (sign_extend (trunc (shl X, (sub (sub result_size, n), m)))) for
// result_size - n != m.
// If truncate is free for the target sext(shl) is likely to result in better
// code.
if (N0.getOpcode() == ISD::SHL && N1C) {
// Get the two constanst of the shifts, CN0 = m, CN = n.
const ConstantSDNode *N01C = isConstOrConstSplat(N0.getOperand(1));
if (N01C) {
LLVMContext &Ctx = *DAG.getContext();
// Determine what the truncate's result bitsize and type would be.
EVT TruncVT = EVT::getIntegerVT(Ctx, OpSizeInBits - N1C->getZExtValue());
if (VT.isVector())
TruncVT = EVT::getVectorVT(Ctx, TruncVT, VT.getVectorElementCount());
// Determine the residual right-shift amount.
int ShiftAmt = N1C->getZExtValue() - N01C->getZExtValue();
// If the shift is not a no-op (in which case this should be just a sign
// extend already), the truncated to type is legal, sign_extend is legal
// on that type, and the truncate to that type is both legal and free,
// perform the transform.
if ((ShiftAmt > 0) &&
TLI.isOperationLegalOrCustom(ISD::SIGN_EXTEND, TruncVT) &&
TLI.isOperationLegalOrCustom(ISD::TRUNCATE, VT) &&
TLI.isTruncateFree(VT, TruncVT)) {
SDLoc DL(N);
SDValue Amt = DAG.getConstant(ShiftAmt, DL,
getShiftAmountTy(N0.getOperand(0).getValueType()));
SDValue Shift = DAG.getNode(ISD::SRL, DL, VT,
N0.getOperand(0), Amt);
SDValue Trunc = DAG.getNode(ISD::TRUNCATE, DL, TruncVT,
Shift);
return DAG.getNode(ISD::SIGN_EXTEND, DL,
N->getValueType(0), Trunc);
}
}
}
// We convert trunc/ext to opposing shifts in IR, but casts may be cheaper.
// sra (add (shl X, N1C), AddC), N1C -->
// sext (add (trunc X to (width - N1C)), AddC')
if (N0.getOpcode() == ISD::ADD && N0.hasOneUse() && N1C &&
N0.getOperand(0).getOpcode() == ISD::SHL &&
N0.getOperand(0).getOperand(1) == N1 && N0.getOperand(0).hasOneUse()) {
if (ConstantSDNode *AddC = isConstOrConstSplat(N0.getOperand(1))) {
SDValue Shl = N0.getOperand(0);
// Determine what the truncate's type would be and ask the target if that
// is a free operation.
LLVMContext &Ctx = *DAG.getContext();
unsigned ShiftAmt = N1C->getZExtValue();
EVT TruncVT = EVT::getIntegerVT(Ctx, OpSizeInBits - ShiftAmt);
if (VT.isVector())
TruncVT = EVT::getVectorVT(Ctx, TruncVT, VT.getVectorElementCount());
// TODO: The simple type check probably belongs in the default hook
// implementation and/or target-specific overrides (because
// non-simple types likely require masking when legalized), but that
// restriction may conflict with other transforms.
if (TruncVT.isSimple() && isTypeLegal(TruncVT) &&
TLI.isTruncateFree(VT, TruncVT)) {
SDLoc DL(N);
SDValue Trunc = DAG.getZExtOrTrunc(Shl.getOperand(0), DL, TruncVT);
SDValue ShiftC = DAG.getConstant(AddC->getAPIntValue().lshr(ShiftAmt).
trunc(TruncVT.getScalarSizeInBits()), DL, TruncVT);
SDValue Add = DAG.getNode(ISD::ADD, DL, TruncVT, Trunc, ShiftC);
return DAG.getSExtOrTrunc(Add, DL, VT);
}
}
}
// fold (sra x, (trunc (and y, c))) -> (sra x, (and (trunc y), (trunc c))).
if (N1.getOpcode() == ISD::TRUNCATE &&
N1.getOperand(0).getOpcode() == ISD::AND) {
if (SDValue NewOp1 = distributeTruncateThroughAnd(N1.getNode()))
return DAG.getNode(ISD::SRA, SDLoc(N), VT, N0, NewOp1);
}
// fold (sra (trunc (sra x, c1)), c2) -> (trunc (sra x, c1 + c2))
// fold (sra (trunc (srl x, c1)), c2) -> (trunc (sra x, c1 + c2))
// if c1 is equal to the number of bits the trunc removes
// TODO - support non-uniform vector shift amounts.
if (N0.getOpcode() == ISD::TRUNCATE &&
(N0.getOperand(0).getOpcode() == ISD::SRL ||
N0.getOperand(0).getOpcode() == ISD::SRA) &&
N0.getOperand(0).hasOneUse() &&
N0.getOperand(0).getOperand(1).hasOneUse() && N1C) {
SDValue N0Op0 = N0.getOperand(0);
if (ConstantSDNode *LargeShift = isConstOrConstSplat(N0Op0.getOperand(1))) {
EVT LargeVT = N0Op0.getValueType();
unsigned TruncBits = LargeVT.getScalarSizeInBits() - OpSizeInBits;
if (LargeShift->getAPIntValue() == TruncBits) {
SDLoc DL(N);
EVT LargeShiftVT = getShiftAmountTy(LargeVT);
SDValue Amt = DAG.getZExtOrTrunc(N1, DL, LargeShiftVT);
Amt = DAG.getNode(ISD::ADD, DL, LargeShiftVT, Amt,
DAG.getConstant(TruncBits, DL, LargeShiftVT));
SDValue SRA =
DAG.getNode(ISD::SRA, DL, LargeVT, N0Op0.getOperand(0), Amt);
return DAG.getNode(ISD::TRUNCATE, DL, VT, SRA);
}
}
}
// Simplify, based on bits shifted out of the LHS.
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
// If the sign bit is known to be zero, switch this to a SRL.
if (DAG.SignBitIsZero(N0))
return DAG.getNode(ISD::SRL, SDLoc(N), VT, N0, N1);
if (N1C && !N1C->isOpaque())
if (SDValue NewSRA = visitShiftByConstant(N))
return NewSRA;
// Try to transform this shift into a multiply-high if
// it matches the appropriate pattern detected in combineShiftToMULH.
if (SDValue MULH = combineShiftToMULH(N, DAG, TLI))
return MULH;
// Attempt to convert a sra of a load into a narrower sign-extending load.
if (SDValue NarrowLoad = reduceLoadWidth(N))
return NarrowLoad;
return SDValue();
}
SDValue DAGCombiner::visitSRL(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
if (SDValue V = DAG.simplifyShift(N0, N1))
return V;
EVT VT = N0.getValueType();
EVT ShiftVT = N1.getValueType();
unsigned OpSizeInBits = VT.getScalarSizeInBits();
// fold (srl c1, c2) -> c1 >>u c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::SRL, SDLoc(N), VT, {N0, N1}))
return C;
// fold vector ops
if (VT.isVector())
if (SDValue FoldedVOp = SimplifyVBinOp(N, SDLoc(N)))
return FoldedVOp;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
// if (srl x, c) is known to be zero, return 0
ConstantSDNode *N1C = isConstOrConstSplat(N1);
if (N1C &&
DAG.MaskedValueIsZero(SDValue(N, 0), APInt::getAllOnes(OpSizeInBits)))
return DAG.getConstant(0, SDLoc(N), VT);
// fold (srl (srl x, c1), c2) -> 0 or (srl x, (add c1, c2))
if (N0.getOpcode() == ISD::SRL) {
auto MatchOutOfRange = [OpSizeInBits](ConstantSDNode *LHS,
ConstantSDNode *RHS) {
APInt c1 = LHS->getAPIntValue();
APInt c2 = RHS->getAPIntValue();
zeroExtendToMatch(c1, c2, 1 /* Overflow Bit */);
return (c1 + c2).uge(OpSizeInBits);
};
if (ISD::matchBinaryPredicate(N1, N0.getOperand(1), MatchOutOfRange))
return DAG.getConstant(0, SDLoc(N), VT);
auto MatchInRange = [OpSizeInBits](ConstantSDNode *LHS,
ConstantSDNode *RHS) {
APInt c1 = LHS->getAPIntValue();
APInt c2 = RHS->getAPIntValue();
zeroExtendToMatch(c1, c2, 1 /* Overflow Bit */);
return (c1 + c2).ult(OpSizeInBits);
};
if (ISD::matchBinaryPredicate(N1, N0.getOperand(1), MatchInRange)) {
SDLoc DL(N);
SDValue Sum = DAG.getNode(ISD::ADD, DL, ShiftVT, N1, N0.getOperand(1));
return DAG.getNode(ISD::SRL, DL, VT, N0.getOperand(0), Sum);
}
}
if (N1C && N0.getOpcode() == ISD::TRUNCATE &&
N0.getOperand(0).getOpcode() == ISD::SRL) {
SDValue InnerShift = N0.getOperand(0);
// TODO - support non-uniform vector shift amounts.
if (auto *N001C = isConstOrConstSplat(InnerShift.getOperand(1))) {
uint64_t c1 = N001C->getZExtValue();
uint64_t c2 = N1C->getZExtValue();
EVT InnerShiftVT = InnerShift.getValueType();
EVT ShiftAmtVT = InnerShift.getOperand(1).getValueType();
uint64_t InnerShiftSize = InnerShiftVT.getScalarSizeInBits();
// srl (trunc (srl x, c1)), c2 --> 0 or (trunc (srl x, (add c1, c2)))
// This is only valid if the OpSizeInBits + c1 = size of inner shift.
if (c1 + OpSizeInBits == InnerShiftSize) {
SDLoc DL(N);
if (c1 + c2 >= InnerShiftSize)
return DAG.getConstant(0, DL, VT);
SDValue NewShiftAmt = DAG.getConstant(c1 + c2, DL, ShiftAmtVT);
SDValue NewShift = DAG.getNode(ISD::SRL, DL, InnerShiftVT,
InnerShift.getOperand(0), NewShiftAmt);
return DAG.getNode(ISD::TRUNCATE, DL, VT, NewShift);
}
// In the more general case, we can clear the high bits after the shift:
// srl (trunc (srl x, c1)), c2 --> trunc (and (srl x, (c1+c2)), Mask)
if (N0.hasOneUse() && InnerShift.hasOneUse() &&
c1 + c2 < InnerShiftSize) {
SDLoc DL(N);
SDValue NewShiftAmt = DAG.getConstant(c1 + c2, DL, ShiftAmtVT);
SDValue NewShift = DAG.getNode(ISD::SRL, DL, InnerShiftVT,
InnerShift.getOperand(0), NewShiftAmt);
SDValue Mask = DAG.getConstant(APInt::getLowBitsSet(InnerShiftSize,
OpSizeInBits - c2),
DL, InnerShiftVT);
SDValue And = DAG.getNode(ISD::AND, DL, InnerShiftVT, NewShift, Mask);
return DAG.getNode(ISD::TRUNCATE, DL, VT, And);
}
}
}
// fold (srl (shl x, c), c) -> (and x, cst2)
// TODO - (srl (shl x, c1), c2).
if (N0.getOpcode() == ISD::SHL && N0.getOperand(1) == N1 &&
isConstantOrConstantVector(N1, /* NoOpaques */ true)) {
SDLoc DL(N);
SDValue Mask =
DAG.getNode(ISD::SRL, DL, VT, DAG.getAllOnesConstant(DL, VT), N1);
AddToWorklist(Mask.getNode());
return DAG.getNode(ISD::AND, DL, VT, N0.getOperand(0), Mask);
}
// fold (srl (anyextend x), c) -> (and (anyextend (srl x, c)), mask)
// TODO - support non-uniform vector shift amounts.
if (N1C && N0.getOpcode() == ISD::ANY_EXTEND) {
// Shifting in all undef bits?
EVT SmallVT = N0.getOperand(0).getValueType();
unsigned BitSize = SmallVT.getScalarSizeInBits();
if (N1C->getAPIntValue().uge(BitSize))
return DAG.getUNDEF(VT);
if (!LegalTypes || TLI.isTypeDesirableForOp(ISD::SRL, SmallVT)) {
uint64_t ShiftAmt = N1C->getZExtValue();
SDLoc DL0(N0);
SDValue SmallShift = DAG.getNode(ISD::SRL, DL0, SmallVT,
N0.getOperand(0),
DAG.getConstant(ShiftAmt, DL0,
getShiftAmountTy(SmallVT)));
AddToWorklist(SmallShift.getNode());
APInt Mask = APInt::getLowBitsSet(OpSizeInBits, OpSizeInBits - ShiftAmt);
SDLoc DL(N);
return DAG.getNode(ISD::AND, DL, VT,
DAG.getNode(ISD::ANY_EXTEND, DL, VT, SmallShift),
DAG.getConstant(Mask, DL, VT));
}
}
// fold (srl (sra X, Y), 31) -> (srl X, 31). This srl only looks at the sign
// bit, which is unmodified by sra.
if (N1C && N1C->getAPIntValue() == (OpSizeInBits - 1)) {
if (N0.getOpcode() == ISD::SRA)
return DAG.getNode(ISD::SRL, SDLoc(N), VT, N0.getOperand(0), N1);
}
// fold (srl (ctlz x), "5") -> x iff x has one bit set (the low bit).
if (N1C && N0.getOpcode() == ISD::CTLZ &&
N1C->getAPIntValue() == Log2_32(OpSizeInBits)) {
KnownBits Known = DAG.computeKnownBits(N0.getOperand(0));
// If any of the input bits are KnownOne, then the input couldn't be all
// zeros, thus the result of the srl will always be zero.
if (Known.One.getBoolValue()) return DAG.getConstant(0, SDLoc(N0), VT);
// If all of the bits input the to ctlz node are known to be zero, then
// the result of the ctlz is "32" and the result of the shift is one.
APInt UnknownBits = ~Known.Zero;
if (UnknownBits == 0) return DAG.getConstant(1, SDLoc(N0), VT);
// Otherwise, check to see if there is exactly one bit input to the ctlz.
if (UnknownBits.isPowerOf2()) {
// Okay, we know that only that the single bit specified by UnknownBits
// could be set on input to the CTLZ node. If this bit is set, the SRL
// will return 0, if it is clear, it returns 1. Change the CTLZ/SRL pair
// to an SRL/XOR pair, which is likely to simplify more.
unsigned ShAmt = UnknownBits.countTrailingZeros();
SDValue Op = N0.getOperand(0);
if (ShAmt) {
SDLoc DL(N0);
Op = DAG.getNode(ISD::SRL, DL, VT, Op,
DAG.getConstant(ShAmt, DL,
getShiftAmountTy(Op.getValueType())));
AddToWorklist(Op.getNode());
}
SDLoc DL(N);
return DAG.getNode(ISD::XOR, DL, VT,
Op, DAG.getConstant(1, DL, VT));
}
}
// fold (srl x, (trunc (and y, c))) -> (srl x, (and (trunc y), (trunc c))).
if (N1.getOpcode() == ISD::TRUNCATE &&
N1.getOperand(0).getOpcode() == ISD::AND) {
if (SDValue NewOp1 = distributeTruncateThroughAnd(N1.getNode()))
return DAG.getNode(ISD::SRL, SDLoc(N), VT, N0, NewOp1);
}
// fold operands of srl based on knowledge that the low bits are not
// demanded.
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
if (N1C && !N1C->isOpaque())
if (SDValue NewSRL = visitShiftByConstant(N))
return NewSRL;
// Attempt to convert a srl of a load into a narrower zero-extending load.
if (SDValue NarrowLoad = reduceLoadWidth(N))
return NarrowLoad;
// Here is a common situation. We want to optimize:
//
// %a = ...
// %b = and i32 %a, 2
// %c = srl i32 %b, 1
// brcond i32 %c ...
//
// into
//
// %a = ...
// %b = and %a, 2
// %c = setcc eq %b, 0
// brcond %c ...
//
// However when after the source operand of SRL is optimized into AND, the SRL
// itself may not be optimized further. Look for it and add the BRCOND into
// the worklist.
if (N->hasOneUse()) {
SDNode *Use = *N->use_begin();
if (Use->getOpcode() == ISD::BRCOND)
AddToWorklist(Use);
else if (Use->getOpcode() == ISD::TRUNCATE && Use->hasOneUse()) {
// Also look pass the truncate.
Use = *Use->use_begin();
if (Use->getOpcode() == ISD::BRCOND)
AddToWorklist(Use);
}
}
// Try to transform this shift into a multiply-high if
// it matches the appropriate pattern detected in combineShiftToMULH.
if (SDValue MULH = combineShiftToMULH(N, DAG, TLI))
return MULH;
return SDValue();
}
SDValue DAGCombiner::visitFunnelShift(SDNode *N) {
EVT VT = N->getValueType(0);
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
bool IsFSHL = N->getOpcode() == ISD::FSHL;
unsigned BitWidth = VT.getScalarSizeInBits();
// fold (fshl N0, N1, 0) -> N0
// fold (fshr N0, N1, 0) -> N1
if (isPowerOf2_32(BitWidth))
if (DAG.MaskedValueIsZero(
N2, APInt(N2.getScalarValueSizeInBits(), BitWidth - 1)))
return IsFSHL ? N0 : N1;
auto IsUndefOrZero = [](SDValue V) {
return V.isUndef() || isNullOrNullSplat(V, /*AllowUndefs*/ true);
};
// TODO - support non-uniform vector shift amounts.
if (ConstantSDNode *Cst = isConstOrConstSplat(N2)) {
EVT ShAmtTy = N2.getValueType();
// fold (fsh* N0, N1, c) -> (fsh* N0, N1, c % BitWidth)
if (Cst->getAPIntValue().uge(BitWidth)) {
uint64_t RotAmt = Cst->getAPIntValue().urem(BitWidth);
return DAG.getNode(N->getOpcode(), SDLoc(N), VT, N0, N1,
DAG.getConstant(RotAmt, SDLoc(N), ShAmtTy));
}
unsigned ShAmt = Cst->getZExtValue();
if (ShAmt == 0)
return IsFSHL ? N0 : N1;
// fold fshl(undef_or_zero, N1, C) -> lshr(N1, BW-C)
// fold fshr(undef_or_zero, N1, C) -> lshr(N1, C)
// fold fshl(N0, undef_or_zero, C) -> shl(N0, C)
// fold fshr(N0, undef_or_zero, C) -> shl(N0, BW-C)
if (IsUndefOrZero(N0))
return DAG.getNode(ISD::SRL, SDLoc(N), VT, N1,
DAG.getConstant(IsFSHL ? BitWidth - ShAmt : ShAmt,
SDLoc(N), ShAmtTy));
if (IsUndefOrZero(N1))
return DAG.getNode(ISD::SHL, SDLoc(N), VT, N0,
DAG.getConstant(IsFSHL ? ShAmt : BitWidth - ShAmt,
SDLoc(N), ShAmtTy));
// fold (fshl ld1, ld0, c) -> (ld0[ofs]) iff ld0 and ld1 are consecutive.
// fold (fshr ld1, ld0, c) -> (ld0[ofs]) iff ld0 and ld1 are consecutive.
// TODO - bigendian support once we have test coverage.
// TODO - can we merge this with CombineConseutiveLoads/MatchLoadCombine?
// TODO - permit LHS EXTLOAD if extensions are shifted out.
if ((BitWidth % 8) == 0 && (ShAmt % 8) == 0 && !VT.isVector() &&
!DAG.getDataLayout().isBigEndian()) {
auto *LHS = dyn_cast<LoadSDNode>(N0);
auto *RHS = dyn_cast<LoadSDNode>(N1);
if (LHS && RHS && LHS->isSimple() && RHS->isSimple() &&
LHS->getAddressSpace() == RHS->getAddressSpace() &&
(LHS->hasOneUse() || RHS->hasOneUse()) && ISD::isNON_EXTLoad(RHS) &&
ISD::isNON_EXTLoad(LHS)) {
if (DAG.areNonVolatileConsecutiveLoads(LHS, RHS, BitWidth / 8, 1)) {
SDLoc DL(RHS);
uint64_t PtrOff =
IsFSHL ? (((BitWidth - ShAmt) % BitWidth) / 8) : (ShAmt / 8);
Align NewAlign = commonAlignment(RHS->getAlign(), PtrOff);
bool Fast = false;
if (TLI.allowsMemoryAccess(*DAG.getContext(), DAG.getDataLayout(), VT,
RHS->getAddressSpace(), NewAlign,
RHS->getMemOperand()->getFlags(), &Fast) &&
Fast) {
SDValue NewPtr = DAG.getMemBasePlusOffset(
RHS->getBasePtr(), TypeSize::Fixed(PtrOff), DL);
AddToWorklist(NewPtr.getNode());
SDValue Load = DAG.getLoad(
VT, DL, RHS->getChain(), NewPtr,
RHS->getPointerInfo().getWithOffset(PtrOff), NewAlign,
RHS->getMemOperand()->getFlags(), RHS->getAAInfo());
// Replace the old load's chain with the new load's chain.
WorklistRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(N1.getValue(1), Load.getValue(1));
return Load;
}
}
}
}
}
// fold fshr(undef_or_zero, N1, N2) -> lshr(N1, N2)
// fold fshl(N0, undef_or_zero, N2) -> shl(N0, N2)
// iff We know the shift amount is in range.
// TODO: when is it worth doing SUB(BW, N2) as well?
if (isPowerOf2_32(BitWidth)) {
APInt ModuloBits(N2.getScalarValueSizeInBits(), BitWidth - 1);
if (IsUndefOrZero(N0) && !IsFSHL && DAG.MaskedValueIsZero(N2, ~ModuloBits))
return DAG.getNode(ISD::SRL, SDLoc(N), VT, N1, N2);
if (IsUndefOrZero(N1) && IsFSHL && DAG.MaskedValueIsZero(N2, ~ModuloBits))
return DAG.getNode(ISD::SHL, SDLoc(N), VT, N0, N2);
}
// fold (fshl N0, N0, N2) -> (rotl N0, N2)
// fold (fshr N0, N0, N2) -> (rotr N0, N2)
// TODO: Investigate flipping this rotate if only one is legal, if funnel shift
// is legal as well we might be better off avoiding non-constant (BW - N2).
unsigned RotOpc = IsFSHL ? ISD::ROTL : ISD::ROTR;
if (N0 == N1 && hasOperation(RotOpc, VT))
return DAG.getNode(RotOpc, SDLoc(N), VT, N0, N2);
// Simplify, based on bits shifted out of N0/N1.
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
return SDValue();
}
SDValue DAGCombiner::visitSHLSAT(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
if (SDValue V = DAG.simplifyShift(N0, N1))
return V;
EVT VT = N0.getValueType();
// fold (*shlsat c1, c2) -> c1<<c2
if (SDValue C =
DAG.FoldConstantArithmetic(N->getOpcode(), SDLoc(N), VT, {N0, N1}))
return C;
ConstantSDNode *N1C = isConstOrConstSplat(N1);
if (!LegalOperations || TLI.isOperationLegalOrCustom(ISD::SHL, VT)) {
// fold (sshlsat x, c) -> (shl x, c)
if (N->getOpcode() == ISD::SSHLSAT && N1C &&
N1C->getAPIntValue().ult(DAG.ComputeNumSignBits(N0)))
return DAG.getNode(ISD::SHL, SDLoc(N), VT, N0, N1);
// fold (ushlsat x, c) -> (shl x, c)
if (N->getOpcode() == ISD::USHLSAT && N1C &&
N1C->getAPIntValue().ule(
DAG.computeKnownBits(N0).countMinLeadingZeros()))
return DAG.getNode(ISD::SHL, SDLoc(N), VT, N0, N1);
}
return SDValue();
}
// Given a ABS node, detect the following pattern:
// (ABS (SUB (EXTEND a), (EXTEND b))).
// Generates UABD/SABD instruction.
static SDValue combineABSToABD(SDNode *N, SelectionDAG &DAG,
const TargetLowering &TLI) {
SDValue AbsOp1 = N->getOperand(0);
SDValue Op0, Op1;
if (AbsOp1.getOpcode() != ISD::SUB)
return SDValue();
Op0 = AbsOp1.getOperand(0);
Op1 = AbsOp1.getOperand(1);
unsigned Opc0 = Op0.getOpcode();
// Check if the operands of the sub are (zero|sign)-extended.
if (Opc0 != Op1.getOpcode() ||
(Opc0 != ISD::ZERO_EXTEND && Opc0 != ISD::SIGN_EXTEND))
return SDValue();
EVT VT = N->getValueType(0);
EVT VT1 = Op0.getOperand(0).getValueType();
EVT VT2 = Op1.getOperand(0).getValueType();
unsigned ABDOpcode = (Opc0 == ISD::SIGN_EXTEND) ? ISD::ABDS : ISD::ABDU;
// fold abs(sext(x) - sext(y)) -> zext(abds(x, y))
// fold abs(zext(x) - zext(y)) -> zext(abdu(x, y))
// NOTE: Extensions must be equivalent.
if (VT1 == VT2 && TLI.isOperationLegalOrCustom(ABDOpcode, VT1)) {
Op0 = Op0.getOperand(0);
Op1 = Op1.getOperand(0);
SDValue ABD = DAG.getNode(ABDOpcode, SDLoc(N), VT1, Op0, Op1);
return DAG.getNode(ISD::ZERO_EXTEND, SDLoc(N), VT, ABD);
}
// fold abs(sext(x) - sext(y)) -> abds(sext(x), sext(y))
// fold abs(zext(x) - zext(y)) -> abdu(zext(x), zext(y))
if (TLI.isOperationLegalOrCustom(ABDOpcode, VT))
return DAG.getNode(ABDOpcode, SDLoc(N), VT, Op0, Op1);
return SDValue();
}
SDValue DAGCombiner::visitABS(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (abs c1) -> c2
if (DAG.isConstantIntBuildVectorOrConstantInt(N0))
return DAG.getNode(ISD::ABS, SDLoc(N), VT, N0);
// fold (abs (abs x)) -> (abs x)
if (N0.getOpcode() == ISD::ABS)
return N0;
// fold (abs x) -> x iff not-negative
if (DAG.SignBitIsZero(N0))
return N0;
if (SDValue ABD = combineABSToABD(N, DAG, TLI))
return ABD;
return SDValue();
}
SDValue DAGCombiner::visitBSWAP(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
SDLoc DL(N);
// fold (bswap c1) -> c2
if (DAG.isConstantIntBuildVectorOrConstantInt(N0))
return DAG.getNode(ISD::BSWAP, DL, VT, N0);
// fold (bswap (bswap x)) -> x
if (N0.getOpcode() == ISD::BSWAP)
return N0.getOperand(0);
// Canonicalize bswap(bitreverse(x)) -> bitreverse(bswap(x)). If bitreverse
// isn't supported, it will be expanded to bswap followed by a manual reversal
// of bits in each byte. By placing bswaps before bitreverse, we can remove
// the two bswaps if the bitreverse gets expanded.
if (N0.getOpcode() == ISD::BITREVERSE && N0.hasOneUse()) {
SDValue BSwap = DAG.getNode(ISD::BSWAP, DL, VT, N0.getOperand(0));
return DAG.getNode(ISD::BITREVERSE, DL, VT, BSwap);
}
// fold (bswap shl(x,c)) -> (zext(bswap(trunc(shl(x,sub(c,bw/2))))))
// iff x >= bw/2 (i.e. lower half is known zero)
unsigned BW = VT.getScalarSizeInBits();
if (BW >= 32 && N0.getOpcode() == ISD::SHL && N0.hasOneUse()) {
auto *ShAmt = dyn_cast<ConstantSDNode>(N0.getOperand(1));
EVT HalfVT = EVT::getIntegerVT(*DAG.getContext(), BW / 2);
if (ShAmt && ShAmt->getAPIntValue().ult(BW) &&
ShAmt->getZExtValue() >= (BW / 2) &&
(ShAmt->getZExtValue() % 16) == 0 && TLI.isTypeLegal(HalfVT) &&
TLI.isTruncateFree(VT, HalfVT) &&
(!LegalOperations || hasOperation(ISD::BSWAP, HalfVT))) {
SDValue Res = N0.getOperand(0);
if (uint64_t NewShAmt = (ShAmt->getZExtValue() - (BW / 2)))
Res = DAG.getNode(ISD::SHL, DL, VT, Res,
DAG.getConstant(NewShAmt, DL, getShiftAmountTy(VT)));
Res = DAG.getZExtOrTrunc(Res, DL, HalfVT);
Res = DAG.getNode(ISD::BSWAP, DL, HalfVT, Res);
return DAG.getZExtOrTrunc(Res, DL, VT);
}
}
// Try to canonicalize bswap-of-logical-shift-by-8-bit-multiple as
// inverse-shift-of-bswap:
// bswap (X u<< C) --> (bswap X) u>> C
// bswap (X u>> C) --> (bswap X) u<< C
if ((N0.getOpcode() == ISD::SHL || N0.getOpcode() == ISD::SRL) &&
N0.hasOneUse()) {
auto *ShAmt = dyn_cast<ConstantSDNode>(N0.getOperand(1));
if (ShAmt && ShAmt->getAPIntValue().ult(BW) &&
ShAmt->getZExtValue() % 8 == 0) {
SDValue NewSwap = DAG.getNode(ISD::BSWAP, DL, VT, N0.getOperand(0));
unsigned InverseShift = N0.getOpcode() == ISD::SHL ? ISD::SRL : ISD::SHL;
return DAG.getNode(InverseShift, DL, VT, NewSwap, N0.getOperand(1));
}
}
return SDValue();
}
SDValue DAGCombiner::visitBITREVERSE(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (bitreverse c1) -> c2
if (DAG.isConstantIntBuildVectorOrConstantInt(N0))
return DAG.getNode(ISD::BITREVERSE, SDLoc(N), VT, N0);
// fold (bitreverse (bitreverse x)) -> x
if (N0.getOpcode() == ISD::BITREVERSE)
return N0.getOperand(0);
return SDValue();
}
SDValue DAGCombiner::visitCTLZ(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (ctlz c1) -> c2
if (DAG.isConstantIntBuildVectorOrConstantInt(N0))
return DAG.getNode(ISD::CTLZ, SDLoc(N), VT, N0);
// If the value is known never to be zero, switch to the undef version.
if (!LegalOperations || TLI.isOperationLegal(ISD::CTLZ_ZERO_UNDEF, VT)) {
if (DAG.isKnownNeverZero(N0))
return DAG.getNode(ISD::CTLZ_ZERO_UNDEF, SDLoc(N), VT, N0);
}
return SDValue();
}
SDValue DAGCombiner::visitCTLZ_ZERO_UNDEF(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (ctlz_zero_undef c1) -> c2
if (DAG.isConstantIntBuildVectorOrConstantInt(N0))
return DAG.getNode(ISD::CTLZ_ZERO_UNDEF, SDLoc(N), VT, N0);
return SDValue();
}
SDValue DAGCombiner::visitCTTZ(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (cttz c1) -> c2
if (DAG.isConstantIntBuildVectorOrConstantInt(N0))
return DAG.getNode(ISD::CTTZ, SDLoc(N), VT, N0);
// If the value is known never to be zero, switch to the undef version.
if (!LegalOperations || TLI.isOperationLegal(ISD::CTTZ_ZERO_UNDEF, VT)) {
if (DAG.isKnownNeverZero(N0))
return DAG.getNode(ISD::CTTZ_ZERO_UNDEF, SDLoc(N), VT, N0);
}
return SDValue();
}
SDValue DAGCombiner::visitCTTZ_ZERO_UNDEF(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (cttz_zero_undef c1) -> c2
if (DAG.isConstantIntBuildVectorOrConstantInt(N0))
return DAG.getNode(ISD::CTTZ_ZERO_UNDEF, SDLoc(N), VT, N0);
return SDValue();
}
SDValue DAGCombiner::visitCTPOP(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (ctpop c1) -> c2
if (DAG.isConstantIntBuildVectorOrConstantInt(N0))
return DAG.getNode(ISD::CTPOP, SDLoc(N), VT, N0);
return SDValue();
}
// FIXME: This should be checking for no signed zeros on individual operands, as
// well as no nans.
static bool isLegalToCombineMinNumMaxNum(SelectionDAG &DAG, SDValue LHS,
SDValue RHS,
const TargetLowering &TLI) {
const TargetOptions &Options = DAG.getTarget().Options;
EVT VT = LHS.getValueType();
return Options.NoSignedZerosFPMath && VT.isFloatingPoint() &&
TLI.isProfitableToCombineMinNumMaxNum(VT) &&
DAG.isKnownNeverNaN(LHS) && DAG.isKnownNeverNaN(RHS);
}
/// Generate Min/Max node
static SDValue combineMinNumMaxNum(const SDLoc &DL, EVT VT, SDValue LHS,
SDValue RHS, SDValue True, SDValue False,
ISD::CondCode CC, const TargetLowering &TLI,
SelectionDAG &DAG) {
if (!(LHS == True && RHS == False) && !(LHS == False && RHS == True))
return SDValue();
EVT TransformVT = TLI.getTypeToTransformTo(*DAG.getContext(), VT);
switch (CC) {
case ISD::SETOLT:
case ISD::SETOLE:
case ISD::SETLT:
case ISD::SETLE:
case ISD::SETULT:
case ISD::SETULE: {
// Since it's known never nan to get here already, either fminnum or
// fminnum_ieee are OK. Try the ieee version first, since it's fminnum is
// expanded in terms of it.
unsigned IEEEOpcode = (LHS == True) ? ISD::FMINNUM_IEEE : ISD::FMAXNUM_IEEE;
if (TLI.isOperationLegalOrCustom(IEEEOpcode, VT))
return DAG.getNode(IEEEOpcode, DL, VT, LHS, RHS);
unsigned Opcode = (LHS == True) ? ISD::FMINNUM : ISD::FMAXNUM;
if (TLI.isOperationLegalOrCustom(Opcode, TransformVT))
return DAG.getNode(Opcode, DL, VT, LHS, RHS);
return SDValue();
}
case ISD::SETOGT:
case ISD::SETOGE:
case ISD::SETGT:
case ISD::SETGE:
case ISD::SETUGT:
case ISD::SETUGE: {
unsigned IEEEOpcode = (LHS == True) ? ISD::FMAXNUM_IEEE : ISD::FMINNUM_IEEE;
if (TLI.isOperationLegalOrCustom(IEEEOpcode, VT))
return DAG.getNode(IEEEOpcode, DL, VT, LHS, RHS);
unsigned Opcode = (LHS == True) ? ISD::FMAXNUM : ISD::FMINNUM;
if (TLI.isOperationLegalOrCustom(Opcode, TransformVT))
return DAG.getNode(Opcode, DL, VT, LHS, RHS);
return SDValue();
}
default:
return SDValue();
}
}
/// If a (v)select has a condition value that is a sign-bit test, try to smear
/// the condition operand sign-bit across the value width and use it as a mask.
static SDValue foldSelectOfConstantsUsingSra(SDNode *N, SelectionDAG &DAG) {
SDValue Cond = N->getOperand(0);
SDValue C1 = N->getOperand(1);
SDValue C2 = N->getOperand(2);
if (!isConstantOrConstantVector(C1) || !isConstantOrConstantVector(C2))
return SDValue();
EVT VT = N->getValueType(0);
if (Cond.getOpcode() != ISD::SETCC || !Cond.hasOneUse() ||
VT != Cond.getOperand(0).getValueType())
return SDValue();
// The inverted-condition + commuted-select variants of these patterns are
// canonicalized to these forms in IR.
SDValue X = Cond.getOperand(0);
SDValue CondC = Cond.getOperand(1);
ISD::CondCode CC = cast<CondCodeSDNode>(Cond.getOperand(2))->get();
if (CC == ISD::SETGT && isAllOnesOrAllOnesSplat(CondC) &&
isAllOnesOrAllOnesSplat(C2)) {
// i32 X > -1 ? C1 : -1 --> (X >>s 31) | C1
SDLoc DL(N);
SDValue ShAmtC = DAG.getConstant(X.getScalarValueSizeInBits() - 1, DL, VT);
SDValue Sra = DAG.getNode(ISD::SRA, DL, VT, X, ShAmtC);
return DAG.getNode(ISD::OR, DL, VT, Sra, C1);
}
if (CC == ISD::SETLT && isNullOrNullSplat(CondC) && isNullOrNullSplat(C2)) {
// i8 X < 0 ? C1 : 0 --> (X >>s 7) & C1
SDLoc DL(N);
SDValue ShAmtC = DAG.getConstant(X.getScalarValueSizeInBits() - 1, DL, VT);
SDValue Sra = DAG.getNode(ISD::SRA, DL, VT, X, ShAmtC);
return DAG.getNode(ISD::AND, DL, VT, Sra, C1);
}
return SDValue();
}
SDValue DAGCombiner::foldSelectOfConstants(SDNode *N) {
SDValue Cond = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
EVT VT = N->getValueType(0);
EVT CondVT = Cond.getValueType();
SDLoc DL(N);
if (!VT.isInteger())
return SDValue();
auto *C1 = dyn_cast<ConstantSDNode>(N1);
auto *C2 = dyn_cast<ConstantSDNode>(N2);
if (!C1 || !C2)
return SDValue();
// Only do this before legalization to avoid conflicting with target-specific
// transforms in the other direction (create a select from a zext/sext). There
// is also a target-independent combine here in DAGCombiner in the other
// direction for (select Cond, -1, 0) when the condition is not i1.
if (CondVT == MVT::i1 && !LegalOperations) {
if (C1->isZero() && C2->isOne()) {
// select Cond, 0, 1 --> zext (!Cond)
SDValue NotCond = DAG.getNOT(DL, Cond, MVT::i1);
if (VT != MVT::i1)
NotCond = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, NotCond);
return NotCond;
}
if (C1->isZero() && C2->isAllOnes()) {
// select Cond, 0, -1 --> sext (!Cond)
SDValue NotCond = DAG.getNOT(DL, Cond, MVT::i1);
if (VT != MVT::i1)
NotCond = DAG.getNode(ISD::SIGN_EXTEND, DL, VT, NotCond);
return NotCond;
}
if (C1->isOne() && C2->isZero()) {
// select Cond, 1, 0 --> zext (Cond)
if (VT != MVT::i1)
Cond = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, Cond);
return Cond;
}
if (C1->isAllOnes() && C2->isZero()) {
// select Cond, -1, 0 --> sext (Cond)
if (VT != MVT::i1)
Cond = DAG.getNode(ISD::SIGN_EXTEND, DL, VT, Cond);
return Cond;
}
// Use a target hook because some targets may prefer to transform in the
// other direction.
if (TLI.convertSelectOfConstantsToMath(VT)) {
// For any constants that differ by 1, we can transform the select into an
// extend and add.
const APInt &C1Val = C1->getAPIntValue();
const APInt &C2Val = C2->getAPIntValue();
if (C1Val - 1 == C2Val) {
// select Cond, C1, C1-1 --> add (zext Cond), C1-1
if (VT != MVT::i1)
Cond = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, Cond);
return DAG.getNode(ISD::ADD, DL, VT, Cond, N2);
}
if (C1Val + 1 == C2Val) {
// select Cond, C1, C1+1 --> add (sext Cond), C1+1
if (VT != MVT::i1)
Cond = DAG.getNode(ISD::SIGN_EXTEND, DL, VT, Cond);
return DAG.getNode(ISD::ADD, DL, VT, Cond, N2);
}
// select Cond, Pow2, 0 --> (zext Cond) << log2(Pow2)
if (C1Val.isPowerOf2() && C2Val.isZero()) {
if (VT != MVT::i1)
Cond = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, Cond);
SDValue ShAmtC =
DAG.getShiftAmountConstant(C1Val.exactLogBase2(), VT, DL);
return DAG.getNode(ISD::SHL, DL, VT, Cond, ShAmtC);
}
if (SDValue V = foldSelectOfConstantsUsingSra(N, DAG))
return V;
}
return SDValue();
}
// fold (select Cond, 0, 1) -> (xor Cond, 1)
// We can't do this reliably if integer based booleans have different contents
// to floating point based booleans. This is because we can't tell whether we
// have an integer-based boolean or a floating-point-based boolean unless we
// can find the SETCC that produced it and inspect its operands. This is
// fairly easy if C is the SETCC node, but it can potentially be
// undiscoverable (or not reasonably discoverable). For example, it could be
// in another basic block or it could require searching a complicated
// expression.
if (CondVT.isInteger() &&
TLI.getBooleanContents(/*isVec*/false, /*isFloat*/true) ==
TargetLowering::ZeroOrOneBooleanContent &&
TLI.getBooleanContents(/*isVec*/false, /*isFloat*/false) ==
TargetLowering::ZeroOrOneBooleanContent &&
C1->isZero() && C2->isOne()) {
SDValue NotCond =
DAG.getNode(ISD::XOR, DL, CondVT, Cond, DAG.getConstant(1, DL, CondVT));
if (VT.bitsEq(CondVT))
return NotCond;
return DAG.getZExtOrTrunc(NotCond, DL, VT);
}
return SDValue();
}
static SDValue foldBoolSelectToLogic(SDNode *N, SelectionDAG &DAG) {
assert((N->getOpcode() == ISD::SELECT || N->getOpcode() == ISD::VSELECT) &&
"Expected a (v)select");
SDValue Cond = N->getOperand(0);
SDValue T = N->getOperand(1), F = N->getOperand(2);
EVT VT = N->getValueType(0);
if (VT != Cond.getValueType() || VT.getScalarSizeInBits() != 1)
return SDValue();
// select Cond, Cond, F --> or Cond, F
// select Cond, 1, F --> or Cond, F
if (Cond == T || isOneOrOneSplat(T, /* AllowUndefs */ true))
return DAG.getNode(ISD::OR, SDLoc(N), VT, Cond, F);
// select Cond, T, Cond --> and Cond, T
// select Cond, T, 0 --> and Cond, T
if (Cond == F || isNullOrNullSplat(F, /* AllowUndefs */ true))
return DAG.getNode(ISD::AND, SDLoc(N), VT, Cond, T);
// select Cond, T, 1 --> or (not Cond), T
if (isOneOrOneSplat(F, /* AllowUndefs */ true)) {
SDValue NotCond = DAG.getNOT(SDLoc(N), Cond, VT);
return DAG.getNode(ISD::OR, SDLoc(N), VT, NotCond, T);
}
// select Cond, 0, F --> and (not Cond), F
if (isNullOrNullSplat(T, /* AllowUndefs */ true)) {
SDValue NotCond = DAG.getNOT(SDLoc(N), Cond, VT);
return DAG.getNode(ISD::AND, SDLoc(N), VT, NotCond, F);
}
return SDValue();
}
static SDValue foldVSelectToSignBitSplatMask(SDNode *N, SelectionDAG &DAG) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
EVT VT = N->getValueType(0);
if (N0.getOpcode() != ISD::SETCC || !N0.hasOneUse())
return SDValue();
SDValue Cond0 = N0.getOperand(0);
SDValue Cond1 = N0.getOperand(1);
ISD::CondCode CC = cast<CondCodeSDNode>(N0.getOperand(2))->get();
if (VT != Cond0.getValueType())
return SDValue();
// Match a signbit check of Cond0 as "Cond0 s<0". Swap select operands if the
// compare is inverted from that pattern ("Cond0 s> -1").
if (CC == ISD::SETLT && isNullOrNullSplat(Cond1))
; // This is the pattern we are looking for.
else if (CC == ISD::SETGT && isAllOnesOrAllOnesSplat(Cond1))
std::swap(N1, N2);
else
return SDValue();
// (Cond0 s< 0) ? N1 : 0 --> (Cond0 s>> BW-1) & N1
if (isNullOrNullSplat(N2)) {
SDLoc DL(N);
SDValue ShiftAmt = DAG.getConstant(VT.getScalarSizeInBits() - 1, DL, VT);
SDValue Sra = DAG.getNode(ISD::SRA, DL, VT, Cond0, ShiftAmt);
return DAG.getNode(ISD::AND, DL, VT, Sra, N1);
}
// (Cond0 s< 0) ? -1 : N2 --> (Cond0 s>> BW-1) | N2
if (isAllOnesOrAllOnesSplat(N1)) {
SDLoc DL(N);
SDValue ShiftAmt = DAG.getConstant(VT.getScalarSizeInBits() - 1, DL, VT);
SDValue Sra = DAG.getNode(ISD::SRA, DL, VT, Cond0, ShiftAmt);
return DAG.getNode(ISD::OR, DL, VT, Sra, N2);
}
// If we have to invert the sign bit mask, only do that transform if the
// target has a bitwise 'and not' instruction (the invert is free).
// (Cond0 s< -0) ? 0 : N2 --> ~(Cond0 s>> BW-1) & N2
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
if (isNullOrNullSplat(N1) && TLI.hasAndNot(N1)) {
SDLoc DL(N);
SDValue ShiftAmt = DAG.getConstant(VT.getScalarSizeInBits() - 1, DL, VT);
SDValue Sra = DAG.getNode(ISD::SRA, DL, VT, Cond0, ShiftAmt);
SDValue Not = DAG.getNOT(DL, Sra, VT);
return DAG.getNode(ISD::AND, DL, VT, Not, N2);
}
// TODO: There's another pattern in this family, but it may require
// implementing hasOrNot() to check for profitability:
// (Cond0 s> -1) ? -1 : N2 --> ~(Cond0 s>> BW-1) | N2
return SDValue();
}
SDValue DAGCombiner::visitSELECT(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
EVT VT = N->getValueType(0);
EVT VT0 = N0.getValueType();
SDLoc DL(N);
SDNodeFlags Flags = N->getFlags();
if (SDValue V = DAG.simplifySelect(N0, N1, N2))
return V;
if (SDValue V = foldSelectOfConstants(N))
return V;
if (SDValue V = foldBoolSelectToLogic(N, DAG))
return V;
// If we can fold this based on the true/false value, do so.
if (SimplifySelectOps(N, N1, N2))
return SDValue(N, 0); // Don't revisit N.
if (VT0 == MVT::i1) {
// The code in this block deals with the following 2 equivalences:
// select(C0|C1, x, y) <=> select(C0, x, select(C1, x, y))
// select(C0&C1, x, y) <=> select(C0, select(C1, x, y), y)
// The target can specify its preferred form with the
// shouldNormalizeToSelectSequence() callback. However we always transform
// to the right anyway if we find the inner select exists in the DAG anyway
// and we always transform to the left side if we know that we can further
// optimize the combination of the conditions.
bool normalizeToSequence =
TLI.shouldNormalizeToSelectSequence(*DAG.getContext(), VT);
// select (and Cond0, Cond1), X, Y
// -> select Cond0, (select Cond1, X, Y), Y
if (N0->getOpcode() == ISD::AND && N0->hasOneUse()) {
SDValue Cond0 = N0->getOperand(0);
SDValue Cond1 = N0->getOperand(1);
SDValue InnerSelect =
DAG.getNode(ISD::SELECT, DL, N1.getValueType(), Cond1, N1, N2, Flags);
if (normalizeToSequence || !InnerSelect.use_empty())
return DAG.getNode(ISD::SELECT, DL, N1.getValueType(), Cond0,
InnerSelect, N2, Flags);
// Cleanup on failure.
if (InnerSelect.use_empty())
recursivelyDeleteUnusedNodes(InnerSelect.getNode());
}
// select (or Cond0, Cond1), X, Y -> select Cond0, X, (select Cond1, X, Y)
if (N0->getOpcode() == ISD::OR && N0->hasOneUse()) {
SDValue Cond0 = N0->getOperand(0);
SDValue Cond1 = N0->getOperand(1);
SDValue InnerSelect = DAG.getNode(ISD::SELECT, DL, N1.getValueType(),
Cond1, N1, N2, Flags);
if (normalizeToSequence || !InnerSelect.use_empty())
return DAG.getNode(ISD::SELECT, DL, N1.getValueType(), Cond0, N1,
InnerSelect, Flags);
// Cleanup on failure.
if (InnerSelect.use_empty())
recursivelyDeleteUnusedNodes(InnerSelect.getNode());
}
// select Cond0, (select Cond1, X, Y), Y -> select (and Cond0, Cond1), X, Y
if (N1->getOpcode() == ISD::SELECT && N1->hasOneUse()) {
SDValue N1_0 = N1->getOperand(0);
SDValue N1_1 = N1->getOperand(1);
SDValue N1_2 = N1->getOperand(2);
if (N1_2 == N2 && N0.getValueType() == N1_0.getValueType()) {
// Create the actual and node if we can generate good code for it.
if (!normalizeToSequence) {
SDValue And = DAG.getNode(ISD::AND, DL, N0.getValueType(), N0, N1_0);
return DAG.getNode(ISD::SELECT, DL, N1.getValueType(), And, N1_1,
N2, Flags);
}
// Otherwise see if we can optimize the "and" to a better pattern.
if (SDValue Combined = visitANDLike(N0, N1_0, N)) {
return DAG.getNode(ISD::SELECT, DL, N1.getValueType(), Combined, N1_1,
N2, Flags);
}
}
}
// select Cond0, X, (select Cond1, X, Y) -> select (or Cond0, Cond1), X, Y
if (N2->getOpcode() == ISD::SELECT && N2->hasOneUse()) {
SDValue N2_0 = N2->getOperand(0);
SDValue N2_1 = N2->getOperand(1);
SDValue N2_2 = N2->getOperand(2);
if (N2_1 == N1 && N0.getValueType() == N2_0.getValueType()) {
// Create the actual or node if we can generate good code for it.
if (!normalizeToSequence) {
SDValue Or = DAG.getNode(ISD::OR, DL, N0.getValueType(), N0, N2_0);
return DAG.getNode(ISD::SELECT, DL, N1.getValueType(), Or, N1,
N2_2, Flags);
}
// Otherwise see if we can optimize to a better pattern.
if (SDValue Combined = visitORLike(N0, N2_0, N))
return DAG.getNode(ISD::SELECT, DL, N1.getValueType(), Combined, N1,
N2_2, Flags);
}
}
}
// select (not Cond), N1, N2 -> select Cond, N2, N1
if (SDValue F = extractBooleanFlip(N0, DAG, TLI, false)) {
SDValue SelectOp = DAG.getSelect(DL, VT, F, N2, N1);
SelectOp->setFlags(Flags);
return SelectOp;
}
// Fold selects based on a setcc into other things, such as min/max/abs.
if (N0.getOpcode() == ISD::SETCC) {
SDValue Cond0 = N0.getOperand(0), Cond1 = N0.getOperand(1);
ISD::CondCode CC = cast<CondCodeSDNode>(N0.getOperand(2))->get();
// select (fcmp lt x, y), x, y -> fminnum x, y
// select (fcmp gt x, y), x, y -> fmaxnum x, y
//
// This is OK if we don't care what happens if either operand is a NaN.
if (N0.hasOneUse() && isLegalToCombineMinNumMaxNum(DAG, N1, N2, TLI))
if (SDValue FMinMax = combineMinNumMaxNum(DL, VT, Cond0, Cond1, N1, N2,
CC, TLI, DAG))
return FMinMax;
// Use 'unsigned add with overflow' to optimize an unsigned saturating add.
// This is conservatively limited to pre-legal-operations to give targets
// a chance to reverse the transform if they want to do that. Also, it is
// unlikely that the pattern would be formed late, so it's probably not
// worth going through the other checks.
if (!LegalOperations && TLI.isOperationLegalOrCustom(ISD::UADDO, VT) &&
CC == ISD::SETUGT && N0.hasOneUse() && isAllOnesConstant(N1) &&
N2.getOpcode() == ISD::ADD && Cond0 == N2.getOperand(0)) {
auto *C = dyn_cast<ConstantSDNode>(N2.getOperand(1));
auto *NotC = dyn_cast<ConstantSDNode>(Cond1);
if (C && NotC && C->getAPIntValue() == ~NotC->getAPIntValue()) {
// select (setcc Cond0, ~C, ugt), -1, (add Cond0, C) -->
// uaddo Cond0, C; select uaddo.1, -1, uaddo.0
//
// The IR equivalent of this transform would have this form:
// %a = add %x, C
// %c = icmp ugt %x, ~C
// %r = select %c, -1, %a
// =>
// %u = call {iN,i1} llvm.uadd.with.overflow(%x, C)
// %u0 = extractvalue %u, 0
// %u1 = extractvalue %u, 1
// %r = select %u1, -1, %u0
SDVTList VTs = DAG.getVTList(VT, VT0);
SDValue UAO = DAG.getNode(ISD::UADDO, DL, VTs, Cond0, N2.getOperand(1));
return DAG.getSelect(DL, VT, UAO.getValue(1), N1, UAO.getValue(0));
}
}
if (TLI.isOperationLegal(ISD::SELECT_CC, VT) ||
(!LegalOperations &&
TLI.isOperationLegalOrCustom(ISD::SELECT_CC, VT))) {
// Any flags available in a select/setcc fold will be on the setcc as they
// migrated from fcmp
Flags = N0->getFlags();
SDValue SelectNode = DAG.getNode(ISD::SELECT_CC, DL, VT, Cond0, Cond1, N1,
N2, N0.getOperand(2));
SelectNode->setFlags(Flags);
return SelectNode;
}
if (SDValue NewSel = SimplifySelect(DL, N0, N1, N2))
return NewSel;
}
if (!VT.isVector())
if (SDValue BinOp = foldSelectOfBinops(N))
return BinOp;
return SDValue();
}
// This function assumes all the vselect's arguments are CONCAT_VECTOR
// nodes and that the condition is a BV of ConstantSDNodes (or undefs).
static SDValue ConvertSelectToConcatVector(SDNode *N, SelectionDAG &DAG) {
SDLoc DL(N);
SDValue Cond = N->getOperand(0);
SDValue LHS = N->getOperand(1);
SDValue RHS = N->getOperand(2);
EVT VT = N->getValueType(0);
int NumElems = VT.getVectorNumElements();
assert(LHS.getOpcode() == ISD::CONCAT_VECTORS &&
RHS.getOpcode() == ISD::CONCAT_VECTORS &&
Cond.getOpcode() == ISD::BUILD_VECTOR);
// CONCAT_VECTOR can take an arbitrary number of arguments. We only care about
// binary ones here.
if (LHS->getNumOperands() != 2 || RHS->getNumOperands() != 2)
return SDValue();
// We're sure we have an even number of elements due to the
// concat_vectors we have as arguments to vselect.
// Skip BV elements until we find one that's not an UNDEF
// After we find an UNDEF element, keep looping until we get to half the
// length of the BV and see if all the non-undef nodes are the same.
ConstantSDNode *BottomHalf = nullptr;
for (int i = 0; i < NumElems / 2; ++i) {
if (Cond->getOperand(i)->isUndef())
continue;
if (BottomHalf == nullptr)
BottomHalf = cast<ConstantSDNode>(Cond.getOperand(i));
else if (Cond->getOperand(i).getNode() != BottomHalf)
return SDValue();
}
// Do the same for the second half of the BuildVector
ConstantSDNode *TopHalf = nullptr;
for (int i = NumElems / 2; i < NumElems; ++i) {
if (Cond->getOperand(i)->isUndef())
continue;
if (TopHalf == nullptr)
TopHalf = cast<ConstantSDNode>(Cond.getOperand(i));
else if (Cond->getOperand(i).getNode() != TopHalf)
return SDValue();
}
assert(TopHalf && BottomHalf &&
"One half of the selector was all UNDEFs and the other was all the "
"same value. This should have been addressed before this function.");
return DAG.getNode(
ISD::CONCAT_VECTORS, DL, VT,
BottomHalf->isZero() ? RHS->getOperand(0) : LHS->getOperand(0),
TopHalf->isZero() ? RHS->getOperand(1) : LHS->getOperand(1));
}
bool refineUniformBase(SDValue &BasePtr, SDValue &Index, bool IndexIsScaled,
SelectionDAG &DAG) {
if (!isNullConstant(BasePtr) || Index.getOpcode() != ISD::ADD)
return false;
// Only perform the transformation when existing operands can be reused.
if (IndexIsScaled)
return false;
// For now we check only the LHS of the add.
SDValue LHS = Index.getOperand(0);
SDValue SplatVal = DAG.getSplatValue(LHS);
if (!SplatVal || SplatVal.getValueType() != BasePtr.getValueType())
return false;
BasePtr = SplatVal;
Index = Index.getOperand(1);
return true;
}
// Fold sext/zext of index into index type.
bool refineIndexType(SDValue &Index, ISD::MemIndexType &IndexType, EVT DataVT,
SelectionDAG &DAG) {
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
// It's always safe to look through zero extends.
if (Index.getOpcode() == ISD::ZERO_EXTEND) {
SDValue Op = Index.getOperand(0);
if (TLI.shouldRemoveExtendFromGSIndex(Op.getValueType(), DataVT)) {
IndexType = ISD::UNSIGNED_SCALED;
Index = Op;
return true;
}
if (ISD::isIndexTypeSigned(IndexType)) {
IndexType = ISD::UNSIGNED_SCALED;
return true;
}
}
// It's only safe to look through sign extends when Index is signed.
if (Index.getOpcode() == ISD::SIGN_EXTEND &&
ISD::isIndexTypeSigned(IndexType)) {
SDValue Op = Index.getOperand(0);
if (TLI.shouldRemoveExtendFromGSIndex(Op.getValueType(), DataVT)) {
Index = Op;
return true;
}
}
return false;
}
SDValue DAGCombiner::visitMSCATTER(SDNode *N) {
MaskedScatterSDNode *MSC = cast<MaskedScatterSDNode>(N);
SDValue Mask = MSC->getMask();
SDValue Chain = MSC->getChain();
SDValue Index = MSC->getIndex();
SDValue Scale = MSC->getScale();
SDValue StoreVal = MSC->getValue();
SDValue BasePtr = MSC->getBasePtr();
ISD::MemIndexType IndexType = MSC->getIndexType();
SDLoc DL(N);
// Zap scatters with a zero mask.
if (ISD::isConstantSplatVectorAllZeros(Mask.getNode()))
return Chain;
if (refineUniformBase(BasePtr, Index, MSC->isIndexScaled(), DAG)) {
SDValue Ops[] = {Chain, StoreVal, Mask, BasePtr, Index, Scale};
return DAG.getMaskedScatter(DAG.getVTList(MVT::Other), MSC->getMemoryVT(),
DL, Ops, MSC->getMemOperand(), IndexType,
MSC->isTruncatingStore());
}
if (refineIndexType(Index, IndexType, StoreVal.getValueType(), DAG)) {
SDValue Ops[] = {Chain, StoreVal, Mask, BasePtr, Index, Scale};
return DAG.getMaskedScatter(DAG.getVTList(MVT::Other), MSC->getMemoryVT(),
DL, Ops, MSC->getMemOperand(), IndexType,
MSC->isTruncatingStore());
}
return SDValue();
}
SDValue DAGCombiner::visitMSTORE(SDNode *N) {
MaskedStoreSDNode *MST = cast<MaskedStoreSDNode>(N);
SDValue Mask = MST->getMask();
SDValue Chain = MST->getChain();
SDValue Value = MST->getValue();
SDValue Ptr = MST->getBasePtr();
SDLoc DL(N);
// Zap masked stores with a zero mask.
if (ISD::isConstantSplatVectorAllZeros(Mask.getNode()))
return Chain;
// If this is a masked load with an all ones mask, we can use a unmasked load.
// FIXME: Can we do this for indexed, compressing, or truncating stores?
if (ISD::isConstantSplatVectorAllOnes(Mask.getNode()) && MST->isUnindexed() &&
!MST->isCompressingStore() && !MST->isTruncatingStore())
return DAG.getStore(MST->getChain(), SDLoc(N), MST->getValue(),
MST->getBasePtr(), MST->getPointerInfo(),
MST->getOriginalAlign(), MachineMemOperand::MOStore,
MST->getAAInfo());
// Try transforming N to an indexed store.
if (CombineToPreIndexedLoadStore(N) || CombineToPostIndexedLoadStore(N))
return SDValue(N, 0);
if (MST->isTruncatingStore() && MST->isUnindexed() &&
Value.getValueType().isInteger() &&
(!isa<ConstantSDNode>(Value) ||
!cast<ConstantSDNode>(Value)->isOpaque())) {
APInt TruncDemandedBits =
APInt::getLowBitsSet(Value.getScalarValueSizeInBits(),
MST->getMemoryVT().getScalarSizeInBits());
// See if we can simplify the operation with
// SimplifyDemandedBits, which only works if the value has a single use.
if (SimplifyDemandedBits(Value, TruncDemandedBits)) {
// Re-visit the store if anything changed and the store hasn't been merged
// with another node (N is deleted) SimplifyDemandedBits will add Value's
// node back to the worklist if necessary, but we also need to re-visit
// the Store node itself.
if (N->getOpcode() != ISD::DELETED_NODE)
AddToWorklist(N);
return SDValue(N, 0);
}
}
// If this is a TRUNC followed by a masked store, fold this into a masked
// truncating store. We can do this even if this is already a masked
// truncstore.
if ((Value.getOpcode() == ISD::TRUNCATE) && Value->hasOneUse() &&
MST->isUnindexed() &&
TLI.canCombineTruncStore(Value.getOperand(0).getValueType(),
MST->getMemoryVT(), LegalOperations)) {
auto Mask = TLI.promoteTargetBoolean(DAG, MST->getMask(),
Value.getOperand(0).getValueType());
return DAG.getMaskedStore(Chain, SDLoc(N), Value.getOperand(0), Ptr,
MST->getOffset(), Mask, MST->getMemoryVT(),
MST->getMemOperand(), MST->getAddressingMode(),
/*IsTruncating=*/true);
}
return SDValue();
}
SDValue DAGCombiner::visitMGATHER(SDNode *N) {
MaskedGatherSDNode *MGT = cast<MaskedGatherSDNode>(N);
SDValue Mask = MGT->getMask();
SDValue Chain = MGT->getChain();
SDValue Index = MGT->getIndex();
SDValue Scale = MGT->getScale();
SDValue PassThru = MGT->getPassThru();
SDValue BasePtr = MGT->getBasePtr();
ISD::MemIndexType IndexType = MGT->getIndexType();
SDLoc DL(N);
// Zap gathers with a zero mask.
if (ISD::isConstantSplatVectorAllZeros(Mask.getNode()))
return CombineTo(N, PassThru, MGT->getChain());
if (refineUniformBase(BasePtr, Index, MGT->isIndexScaled(), DAG)) {
SDValue Ops[] = {Chain, PassThru, Mask, BasePtr, Index, Scale};
return DAG.getMaskedGather(
DAG.getVTList(N->getValueType(0), MVT::Other), MGT->getMemoryVT(), DL,
Ops, MGT->getMemOperand(), IndexType, MGT->getExtensionType());
}
if (refineIndexType(Index, IndexType, N->getValueType(0), DAG)) {
SDValue Ops[] = {Chain, PassThru, Mask, BasePtr, Index, Scale};
return DAG.getMaskedGather(
DAG.getVTList(N->getValueType(0), MVT::Other), MGT->getMemoryVT(), DL,
Ops, MGT->getMemOperand(), IndexType, MGT->getExtensionType());
}
return SDValue();
}
SDValue DAGCombiner::visitMLOAD(SDNode *N) {
MaskedLoadSDNode *MLD = cast<MaskedLoadSDNode>(N);
SDValue Mask = MLD->getMask();
SDLoc DL(N);
// Zap masked loads with a zero mask.
if (ISD::isConstantSplatVectorAllZeros(Mask.getNode()))
return CombineTo(N, MLD->getPassThru(), MLD->getChain());
// If this is a masked load with an all ones mask, we can use a unmasked load.
// FIXME: Can we do this for indexed, expanding, or extending loads?
if (ISD::isConstantSplatVectorAllOnes(Mask.getNode()) && MLD->isUnindexed() &&
!MLD->isExpandingLoad() && MLD->getExtensionType() == ISD::NON_EXTLOAD) {
SDValue NewLd = DAG.getLoad(
N->getValueType(0), SDLoc(N), MLD->getChain(), MLD->getBasePtr(),
MLD->getPointerInfo(), MLD->getOriginalAlign(),
MachineMemOperand::MOLoad, MLD->getAAInfo(), MLD->getRanges());
return CombineTo(N, NewLd, NewLd.getValue(1));
}
// Try transforming N to an indexed load.
if (CombineToPreIndexedLoadStore(N) || CombineToPostIndexedLoadStore(N))
return SDValue(N, 0);
return SDValue();
}
/// A vector select of 2 constant vectors can be simplified to math/logic to
/// avoid a variable select instruction and possibly avoid constant loads.
SDValue DAGCombiner::foldVSelectOfConstants(SDNode *N) {
SDValue Cond = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
EVT VT = N->getValueType(0);
if (!Cond.hasOneUse() || Cond.getScalarValueSizeInBits() != 1 ||
!TLI.convertSelectOfConstantsToMath(VT) ||
!ISD::isBuildVectorOfConstantSDNodes(N1.getNode()) ||
!ISD::isBuildVectorOfConstantSDNodes(N2.getNode()))
return SDValue();
// Check if we can use the condition value to increment/decrement a single
// constant value. This simplifies a select to an add and removes a constant
// load/materialization from the general case.
bool AllAddOne = true;
bool AllSubOne = true;
unsigned Elts = VT.getVectorNumElements();
for (unsigned i = 0; i != Elts; ++i) {
SDValue N1Elt = N1.getOperand(i);
SDValue N2Elt = N2.getOperand(i);
if (N1Elt.isUndef() || N2Elt.isUndef())
continue;
if (N1Elt.getValueType() != N2Elt.getValueType())
continue;
const APInt &C1 = cast<ConstantSDNode>(N1Elt)->getAPIntValue();
const APInt &C2 = cast<ConstantSDNode>(N2Elt)->getAPIntValue();
if (C1 != C2 + 1)
AllAddOne = false;
if (C1 != C2 - 1)
AllSubOne = false;
}
// Further simplifications for the extra-special cases where the constants are
// all 0 or all -1 should be implemented as folds of these patterns.
SDLoc DL(N);
if (AllAddOne || AllSubOne) {
// vselect <N x i1> Cond, C+1, C --> add (zext Cond), C
// vselect <N x i1> Cond, C-1, C --> add (sext Cond), C
auto ExtendOpcode = AllAddOne ? ISD::ZERO_EXTEND : ISD::SIGN_EXTEND;
SDValue ExtendedCond = DAG.getNode(ExtendOpcode, DL, VT, Cond);
return DAG.getNode(ISD::ADD, DL, VT, ExtendedCond, N2);
}
// select Cond, Pow2C, 0 --> (zext Cond) << log2(Pow2C)
APInt Pow2C;
if (ISD::isConstantSplatVector(N1.getNode(), Pow2C) && Pow2C.isPowerOf2() &&
isNullOrNullSplat(N2)) {
SDValue ZextCond = DAG.getZExtOrTrunc(Cond, DL, VT);
SDValue ShAmtC = DAG.getConstant(Pow2C.exactLogBase2(), DL, VT);
return DAG.getNode(ISD::SHL, DL, VT, ZextCond, ShAmtC);
}
if (SDValue V = foldSelectOfConstantsUsingSra(N, DAG))
return V;
// The general case for select-of-constants:
// vselect <N x i1> Cond, C1, C2 --> xor (and (sext Cond), (C1^C2)), C2
// ...but that only makes sense if a vselect is slower than 2 logic ops, so
// leave that to a machine-specific pass.
return SDValue();
}
SDValue DAGCombiner::visitVSELECT(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
EVT VT = N->getValueType(0);
SDLoc DL(N);
if (SDValue V = DAG.simplifySelect(N0, N1, N2))
return V;
if (SDValue V = foldBoolSelectToLogic(N, DAG))
return V;
// vselect (not Cond), N1, N2 -> vselect Cond, N2, N1
if (SDValue F = extractBooleanFlip(N0, DAG, TLI, false))
return DAG.getSelect(DL, VT, F, N2, N1);
// Canonicalize integer abs.
// vselect (setg[te] X, 0), X, -X ->
// vselect (setgt X, -1), X, -X ->
// vselect (setl[te] X, 0), -X, X ->
// Y = sra (X, size(X)-1); xor (add (X, Y), Y)
if (N0.getOpcode() == ISD::SETCC) {
SDValue LHS = N0.getOperand(0), RHS = N0.getOperand(1);
ISD::CondCode CC = cast<CondCodeSDNode>(N0.getOperand(2))->get();
bool isAbs = false;
bool RHSIsAllZeros = ISD::isBuildVectorAllZeros(RHS.getNode());
if (((RHSIsAllZeros && (CC == ISD::SETGT || CC == ISD::SETGE)) ||
(ISD::isBuildVectorAllOnes(RHS.getNode()) && CC == ISD::SETGT)) &&
N1 == LHS && N2.getOpcode() == ISD::SUB && N1 == N2.getOperand(1))
isAbs = ISD::isBuildVectorAllZeros(N2.getOperand(0).getNode());
else if ((RHSIsAllZeros && (CC == ISD::SETLT || CC == ISD::SETLE)) &&
N2 == LHS && N1.getOpcode() == ISD::SUB && N2 == N1.getOperand(1))
isAbs = ISD::isBuildVectorAllZeros(N1.getOperand(0).getNode());
if (isAbs) {
if (TLI.isOperationLegalOrCustom(ISD::ABS, VT))
return DAG.getNode(ISD::ABS, DL, VT, LHS);
SDValue Shift = DAG.getNode(ISD::SRA, DL, VT, LHS,
DAG.getConstant(VT.getScalarSizeInBits() - 1,
DL, getShiftAmountTy(VT)));
SDValue Add = DAG.getNode(ISD::ADD, DL, VT, LHS, Shift);
AddToWorklist(Shift.getNode());
AddToWorklist(Add.getNode());
return DAG.getNode(ISD::XOR, DL, VT, Add, Shift);
}
// vselect x, y (fcmp lt x, y) -> fminnum x, y
// vselect x, y (fcmp gt x, y) -> fmaxnum x, y
//
// This is OK if we don't care about what happens if either operand is a
// NaN.
//
if (N0.hasOneUse() && isLegalToCombineMinNumMaxNum(DAG, LHS, RHS, TLI)) {
if (SDValue FMinMax =
combineMinNumMaxNum(DL, VT, LHS, RHS, N1, N2, CC, TLI, DAG))
return FMinMax;
}
if (SDValue S = PerformMinMaxFpToSatCombine(LHS, RHS, N1, N2, CC, DAG))
return S;
if (SDValue S = PerformUMinFpToSatCombine(LHS, RHS, N1, N2, CC, DAG))
return S;
// If this select has a condition (setcc) with narrower operands than the
// select, try to widen the compare to match the select width.
// TODO: This should be extended to handle any constant.
// TODO: This could be extended to handle non-loading patterns, but that
// requires thorough testing to avoid regressions.
if (isNullOrNullSplat(RHS)) {
EVT NarrowVT = LHS.getValueType();
EVT WideVT = N1.getValueType().changeVectorElementTypeToInteger();
EVT SetCCVT = getSetCCResultType(LHS.getValueType());
unsigned SetCCWidth = SetCCVT.getScalarSizeInBits();
unsigned WideWidth = WideVT.getScalarSizeInBits();
bool IsSigned = isSignedIntSetCC(CC);
auto LoadExtOpcode = IsSigned ? ISD::SEXTLOAD : ISD::ZEXTLOAD;
if (LHS.getOpcode() == ISD::LOAD && LHS.hasOneUse() &&
SetCCWidth != 1 && SetCCWidth < WideWidth &&
TLI.isLoadExtLegalOrCustom(LoadExtOpcode, WideVT, NarrowVT) &&
TLI.isOperationLegalOrCustom(ISD::SETCC, WideVT)) {
// Both compare operands can be widened for free. The LHS can use an
// extended load, and the RHS is a constant:
// vselect (ext (setcc load(X), C)), N1, N2 -->
// vselect (setcc extload(X), C'), N1, N2
auto ExtOpcode = IsSigned ? ISD::SIGN_EXTEND : ISD::ZERO_EXTEND;
SDValue WideLHS = DAG.getNode(ExtOpcode, DL, WideVT, LHS);
SDValue WideRHS = DAG.getNode(ExtOpcode, DL, WideVT, RHS);
EVT WideSetCCVT = getSetCCResultType(WideVT);
SDValue WideSetCC = DAG.getSetCC(DL, WideSetCCVT, WideLHS, WideRHS, CC);
return DAG.getSelect(DL, N1.getValueType(), WideSetCC, N1, N2);
}
}
// Match VSELECTs into add with unsigned saturation.
if (hasOperation(ISD::UADDSAT, VT)) {
// Check if one of the arms of the VSELECT is vector with all bits set.
// If it's on the left side invert the predicate to simplify logic below.
SDValue Other;
ISD::CondCode SatCC = CC;
if (ISD::isConstantSplatVectorAllOnes(N1.getNode())) {
Other = N2;
SatCC = ISD::getSetCCInverse(SatCC, VT.getScalarType());
} else if (ISD::isConstantSplatVectorAllOnes(N2.getNode())) {
Other = N1;
}
if (Other && Other.getOpcode() == ISD::ADD) {
SDValue CondLHS = LHS, CondRHS = RHS;
SDValue OpLHS = Other.getOperand(0), OpRHS = Other.getOperand(1);
// Canonicalize condition operands.
if (SatCC == ISD::SETUGE) {
std::swap(CondLHS, CondRHS);
SatCC = ISD::SETULE;
}
// We can test against either of the addition operands.
// x <= x+y ? x+y : ~0 --> uaddsat x, y
// x+y >= x ? x+y : ~0 --> uaddsat x, y
if (SatCC == ISD::SETULE && Other == CondRHS &&
(OpLHS == CondLHS || OpRHS == CondLHS))
return DAG.getNode(ISD::UADDSAT, DL, VT, OpLHS, OpRHS);
if (OpRHS.getOpcode() == CondRHS.getOpcode() &&
(OpRHS.getOpcode() == ISD::BUILD_VECTOR ||
OpRHS.getOpcode() == ISD::SPLAT_VECTOR) &&
CondLHS == OpLHS) {
// If the RHS is a constant we have to reverse the const
// canonicalization.
// x >= ~C ? x+C : ~0 --> uaddsat x, C
auto MatchUADDSAT = [](ConstantSDNode *Op, ConstantSDNode *Cond) {
return Cond->getAPIntValue() == ~Op->getAPIntValue();
};
if (SatCC == ISD::SETULE &&
ISD::matchBinaryPredicate(OpRHS, CondRHS, MatchUADDSAT))
return DAG.getNode(ISD::UADDSAT, DL, VT, OpLHS, OpRHS);
}
}
}
// Match VSELECTs into sub with unsigned saturation.
if (hasOperation(ISD::USUBSAT, VT)) {
// Check if one of the arms of the VSELECT is a zero vector. If it's on
// the left side invert the predicate to simplify logic below.
SDValue Other;
ISD::CondCode SatCC = CC;
if (ISD::isConstantSplatVectorAllZeros(N1.getNode())) {
Other = N2;
SatCC = ISD::getSetCCInverse(SatCC, VT.getScalarType());
} else if (ISD::isConstantSplatVectorAllZeros(N2.getNode())) {
Other = N1;
}
// zext(x) >= y ? trunc(zext(x) - y) : 0
// --> usubsat(trunc(zext(x)),trunc(umin(y,SatLimit)))
// zext(x) > y ? trunc(zext(x) - y) : 0
// --> usubsat(trunc(zext(x)),trunc(umin(y,SatLimit)))
if (Other && Other.getOpcode() == ISD::TRUNCATE &&
Other.getOperand(0).getOpcode() == ISD::SUB &&
(SatCC == ISD::SETUGE || SatCC == ISD::SETUGT)) {
SDValue OpLHS = Other.getOperand(0).getOperand(0);
SDValue OpRHS = Other.getOperand(0).getOperand(1);
if (LHS == OpLHS && RHS == OpRHS && LHS.getOpcode() == ISD::ZERO_EXTEND)
if (SDValue R = getTruncatedUSUBSAT(VT, LHS.getValueType(), LHS, RHS,
DAG, DL))
return R;
}
if (Other && Other.getNumOperands() == 2) {
SDValue CondRHS = RHS;
SDValue OpLHS = Other.getOperand(0), OpRHS = Other.getOperand(1);
if (OpLHS == LHS) {
// Look for a general sub with unsigned saturation first.
// x >= y ? x-y : 0 --> usubsat x, y
// x > y ? x-y : 0 --> usubsat x, y
if ((SatCC == ISD::SETUGE || SatCC == ISD::SETUGT) &&
Other.getOpcode() == ISD::SUB && OpRHS == CondRHS)
return DAG.getNode(ISD::USUBSAT, DL, VT, OpLHS, OpRHS);
if (OpRHS.getOpcode() == ISD::BUILD_VECTOR ||
OpRHS.getOpcode() == ISD::SPLAT_VECTOR) {
if (CondRHS.getOpcode() == ISD::BUILD_VECTOR ||
CondRHS.getOpcode() == ISD::SPLAT_VECTOR) {
// If the RHS is a constant we have to reverse the const
// canonicalization.
// x > C-1 ? x+-C : 0 --> usubsat x, C
auto MatchUSUBSAT = [](ConstantSDNode *Op, ConstantSDNode *Cond) {
return (!Op && !Cond) ||
(Op && Cond &&
Cond->getAPIntValue() == (-Op->getAPIntValue() - 1));
};
if (SatCC == ISD::SETUGT && Other.getOpcode() == ISD::ADD &&
ISD::matchBinaryPredicate(OpRHS, CondRHS, MatchUSUBSAT,
/*AllowUndefs*/ true)) {
OpRHS = DAG.getNode(ISD::SUB, DL, VT,
DAG.getConstant(0, DL, VT), OpRHS);
return DAG.getNode(ISD::USUBSAT, DL, VT, OpLHS, OpRHS);
}
// Another special case: If C was a sign bit, the sub has been
// canonicalized into a xor.
// FIXME: Would it be better to use computeKnownBits to
// determine whether it's safe to decanonicalize the xor?
// x s< 0 ? x^C : 0 --> usubsat x, C
APInt SplatValue;
if (SatCC == ISD::SETLT && Other.getOpcode() == ISD::XOR &&
ISD::isConstantSplatVector(OpRHS.getNode(), SplatValue) &&
ISD::isConstantSplatVectorAllZeros(CondRHS.getNode()) &&
SplatValue.isSignMask()) {
// Note that we have to rebuild the RHS constant here to
// ensure we don't rely on particular values of undef lanes.
OpRHS = DAG.getConstant(SplatValue, DL, VT);
return DAG.getNode(ISD::USUBSAT, DL, VT, OpLHS, OpRHS);
}
}
}
}
}
}
}
if (SimplifySelectOps(N, N1, N2))
return SDValue(N, 0); // Don't revisit N.
// Fold (vselect all_ones, N1, N2) -> N1
if (ISD::isConstantSplatVectorAllOnes(N0.getNode()))
return N1;
// Fold (vselect all_zeros, N1, N2) -> N2
if (ISD::isConstantSplatVectorAllZeros(N0.getNode()))
return N2;
// The ConvertSelectToConcatVector function is assuming both the above
// checks for (vselect (build_vector all{ones,zeros) ...) have been made
// and addressed.
if (N1.getOpcode() == ISD::CONCAT_VECTORS &&
N2.getOpcode() == ISD::CONCAT_VECTORS &&
ISD::isBuildVectorOfConstantSDNodes(N0.getNode())) {
if (SDValue CV = ConvertSelectToConcatVector(N, DAG))
return CV;
}
if (SDValue V = foldVSelectOfConstants(N))
return V;
if (hasOperation(ISD::SRA, VT))
if (SDValue V = foldVSelectToSignBitSplatMask(N, DAG))
return V;
return SDValue();
}
SDValue DAGCombiner::visitSELECT_CC(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
SDValue N3 = N->getOperand(3);
SDValue N4 = N->getOperand(4);
ISD::CondCode CC = cast<CondCodeSDNode>(N4)->get();
// fold select_cc lhs, rhs, x, x, cc -> x
if (N2 == N3)
return N2;
// Determine if the condition we're dealing with is constant
if (SDValue SCC = SimplifySetCC(getSetCCResultType(N0.getValueType()), N0, N1,
CC, SDLoc(N), false)) {
AddToWorklist(SCC.getNode());
// cond always true -> true val
// cond always false -> false val
if (auto *SCCC = dyn_cast<ConstantSDNode>(SCC.getNode()))
return SCCC->isZero() ? N3 : N2;
// When the condition is UNDEF, just return the first operand. This is
// coherent the DAG creation, no setcc node is created in this case
if (SCC->isUndef())
return N2;
// Fold to a simpler select_cc
if (SCC.getOpcode() == ISD::SETCC) {
SDValue SelectOp = DAG.getNode(
ISD::SELECT_CC, SDLoc(N), N2.getValueType(), SCC.getOperand(0),
SCC.getOperand(1), N2, N3, SCC.getOperand(2));
SelectOp->setFlags(SCC->getFlags());
return SelectOp;
}
}
// If we can fold this based on the true/false value, do so.
if (SimplifySelectOps(N, N2, N3))
return SDValue(N, 0); // Don't revisit N.
// fold select_cc into other things, such as min/max/abs
return SimplifySelectCC(SDLoc(N), N0, N1, N2, N3, CC);
}
SDValue DAGCombiner::visitSETCC(SDNode *N) {
// setcc is very commonly used as an argument to brcond. This pattern
// also lend itself to numerous combines and, as a result, it is desired
// we keep the argument to a brcond as a setcc as much as possible.
bool PreferSetCC =
N->hasOneUse() && N->use_begin()->getOpcode() == ISD::BRCOND;
ISD::CondCode Cond = cast<CondCodeSDNode>(N->getOperand(2))->get();
EVT VT = N->getValueType(0);
// SETCC(FREEZE(X), CONST, Cond)
// =>
// FREEZE(SETCC(X, CONST, Cond))
// This is correct if FREEZE(X) has one use and SETCC(FREEZE(X), CONST, Cond)
// isn't equivalent to true or false.
// For example, SETCC(FREEZE(X), -128, SETULT) cannot be folded to
// FREEZE(SETCC(X, -128, SETULT)) because X can be poison.
//
// This transformation is beneficial because visitBRCOND can fold
// BRCOND(FREEZE(X)) to BRCOND(X).
// Conservatively optimize integer comparisons only.
if (PreferSetCC) {
// Do this only when SETCC is going to be used by BRCOND.
SDValue N0 = N->getOperand(0), N1 = N->getOperand(1);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
bool Updated = false;
// Is 'X Cond C' always true or false?
auto IsAlwaysTrueOrFalse = [](ISD::CondCode Cond, ConstantSDNode *C) {
bool False = (Cond == ISD::SETULT && C->isZero()) ||
(Cond == ISD::SETLT && C->isMinSignedValue()) ||
(Cond == ISD::SETUGT && C->isAllOnes()) ||
(Cond == ISD::SETGT && C->isMaxSignedValue());
bool True = (Cond == ISD::SETULE && C->isAllOnes()) ||
(Cond == ISD::SETLE && C->isMaxSignedValue()) ||
(Cond == ISD::SETUGE && C->isZero()) ||
(Cond == ISD::SETGE && C->isMinSignedValue());
return True || False;
};
if (N0->getOpcode() == ISD::FREEZE && N0.hasOneUse() && N1C) {
if (!IsAlwaysTrueOrFalse(Cond, N1C)) {
N0 = N0->getOperand(0);
Updated = true;
}
}
if (N1->getOpcode() == ISD::FREEZE && N1.hasOneUse() && N0C) {
if (!IsAlwaysTrueOrFalse(ISD::getSetCCSwappedOperands(Cond),
N0C)) {
N1 = N1->getOperand(0);
Updated = true;
}
}
if (Updated)
return DAG.getFreeze(DAG.getSetCC(SDLoc(N), VT, N0, N1, Cond));
}
SDValue Combined = SimplifySetCC(VT, N->getOperand(0), N->getOperand(1), Cond,
SDLoc(N), !PreferSetCC);
if (!Combined)
return SDValue();
// If we prefer to have a setcc, and we don't, we'll try our best to
// recreate one using rebuildSetCC.
if (PreferSetCC && Combined.getOpcode() != ISD::SETCC) {
SDValue NewSetCC = rebuildSetCC(Combined);
// We don't have anything interesting to combine to.
if (NewSetCC.getNode() == N)
return SDValue();
if (NewSetCC)
return NewSetCC;
}
return Combined;
}
SDValue DAGCombiner::visitSETCCCARRY(SDNode *N) {
SDValue LHS = N->getOperand(0);
SDValue RHS = N->getOperand(1);
SDValue Carry = N->getOperand(2);
SDValue Cond = N->getOperand(3);
// If Carry is false, fold to a regular SETCC.
if (isNullConstant(Carry))
return DAG.getNode(ISD::SETCC, SDLoc(N), N->getVTList(), LHS, RHS, Cond);
return SDValue();
}
/// Check if N satisfies:
/// N is used once.
/// N is a Load.
/// The load is compatible with ExtOpcode. It means
/// If load has explicit zero/sign extension, ExpOpcode must have the same
/// extension.
/// Otherwise returns true.
static bool isCompatibleLoad(SDValue N, unsigned ExtOpcode) {
if (!N.hasOneUse())
return false;
if (!isa<LoadSDNode>(N))
return false;
LoadSDNode *Load = cast<LoadSDNode>(N);
ISD::LoadExtType LoadExt = Load->getExtensionType();
if (LoadExt == ISD::NON_EXTLOAD || LoadExt == ISD::EXTLOAD)
return true;
// Now LoadExt is either SEXTLOAD or ZEXTLOAD, ExtOpcode must have the same
// extension.
if ((LoadExt == ISD::SEXTLOAD && ExtOpcode != ISD::SIGN_EXTEND) ||
(LoadExt == ISD::ZEXTLOAD && ExtOpcode != ISD::ZERO_EXTEND))
return false;
return true;
}
/// Fold
/// (sext (select c, load x, load y)) -> (select c, sextload x, sextload y)
/// (zext (select c, load x, load y)) -> (select c, zextload x, zextload y)
/// (aext (select c, load x, load y)) -> (select c, extload x, extload y)
/// This function is called by the DAGCombiner when visiting sext/zext/aext
/// dag nodes (see for example method DAGCombiner::visitSIGN_EXTEND).
static SDValue tryToFoldExtendSelectLoad(SDNode *N, const TargetLowering &TLI,
SelectionDAG &DAG) {
unsigned Opcode = N->getOpcode();
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
SDLoc DL(N);
assert((Opcode == ISD::SIGN_EXTEND || Opcode == ISD::ZERO_EXTEND ||
Opcode == ISD::ANY_EXTEND) &&
"Expected EXTEND dag node in input!");
if (!(N0->getOpcode() == ISD::SELECT || N0->getOpcode() == ISD::VSELECT) ||
!N0.hasOneUse())
return SDValue();
SDValue Op1 = N0->getOperand(1);
SDValue Op2 = N0->getOperand(2);
if (!isCompatibleLoad(Op1, Opcode) || !isCompatibleLoad(Op2, Opcode))
return SDValue();
auto ExtLoadOpcode = ISD::EXTLOAD;
if (Opcode == ISD::SIGN_EXTEND)
ExtLoadOpcode = ISD::SEXTLOAD;
else if (Opcode == ISD::ZERO_EXTEND)
ExtLoadOpcode = ISD::ZEXTLOAD;
LoadSDNode *Load1 = cast<LoadSDNode>(Op1);
LoadSDNode *Load2 = cast<LoadSDNode>(Op2);
if (!TLI.isLoadExtLegal(ExtLoadOpcode, VT, Load1->getMemoryVT()) ||
!TLI.isLoadExtLegal(ExtLoadOpcode, VT, Load2->getMemoryVT()))
return SDValue();
SDValue Ext1 = DAG.getNode(Opcode, DL, VT, Op1);
SDValue Ext2 = DAG.getNode(Opcode, DL, VT, Op2);
return DAG.getSelect(DL, VT, N0->getOperand(0), Ext1, Ext2);
}
/// Try to fold a sext/zext/aext dag node into a ConstantSDNode or
/// a build_vector of constants.
/// This function is called by the DAGCombiner when visiting sext/zext/aext
/// dag nodes (see for example method DAGCombiner::visitSIGN_EXTEND).
/// Vector extends are not folded if operations are legal; this is to
/// avoid introducing illegal build_vector dag nodes.
static SDValue tryToFoldExtendOfConstant(SDNode *N, const TargetLowering &TLI,
SelectionDAG &DAG, bool LegalTypes) {
unsigned Opcode = N->getOpcode();
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
SDLoc DL(N);
assert((Opcode == ISD::SIGN_EXTEND || Opcode == ISD::ZERO_EXTEND ||
Opcode == ISD::ANY_EXTEND || Opcode == ISD::SIGN_EXTEND_VECTOR_INREG ||
Opcode == ISD::ZERO_EXTEND_VECTOR_INREG)
&& "Expected EXTEND dag node in input!");
// fold (sext c1) -> c1
// fold (zext c1) -> c1
// fold (aext c1) -> c1
if (isa<ConstantSDNode>(N0))
return DAG.getNode(Opcode, DL, VT, N0);
// fold (sext (select cond, c1, c2)) -> (select cond, sext c1, sext c2)
// fold (zext (select cond, c1, c2)) -> (select cond, zext c1, zext c2)
// fold (aext (select cond, c1, c2)) -> (select cond, sext c1, sext c2)
if (N0->getOpcode() == ISD::SELECT) {
SDValue Op1 = N0->getOperand(1);
SDValue Op2 = N0->getOperand(2);
if (isa<ConstantSDNode>(Op1) && isa<ConstantSDNode>(Op2) &&
(Opcode != ISD::ZERO_EXTEND || !TLI.isZExtFree(N0.getValueType(), VT))) {
// For any_extend, choose sign extension of the constants to allow a
// possible further transform to sign_extend_inreg.i.e.
//
// t1: i8 = select t0, Constant:i8<-1>, Constant:i8<0>
// t2: i64 = any_extend t1
// -->
// t3: i64 = select t0, Constant:i64<-1>, Constant:i64<0>
// -->
// t4: i64 = sign_extend_inreg t3
unsigned FoldOpc = Opcode;
if (FoldOpc == ISD::ANY_EXTEND)
FoldOpc = ISD::SIGN_EXTEND;
return DAG.getSelect(DL, VT, N0->getOperand(0),
DAG.getNode(FoldOpc, DL, VT, Op1),
DAG.getNode(FoldOpc, DL, VT, Op2));
}
}
// fold (sext (build_vector AllConstants) -> (build_vector AllConstants)
// fold (zext (build_vector AllConstants) -> (build_vector AllConstants)
// fold (aext (build_vector AllConstants) -> (build_vector AllConstants)
EVT SVT = VT.getScalarType();
if (!(VT.isVector() && (!LegalTypes || TLI.isTypeLegal(SVT)) &&
ISD::isBuildVectorOfConstantSDNodes(N0.getNode())))
return SDValue();
// We can fold this node into a build_vector.
unsigned VTBits = SVT.getSizeInBits();
unsigned EVTBits = N0->getValueType(0).getScalarSizeInBits();
SmallVector<SDValue, 8> Elts;
unsigned NumElts = VT.getVectorNumElements();
// For zero-extensions, UNDEF elements still guarantee to have the upper
// bits set to zero.
bool IsZext =
Opcode == ISD::ZERO_EXTEND || Opcode == ISD::ZERO_EXTEND_VECTOR_INREG;
for (unsigned i = 0; i != NumElts; ++i) {
SDValue Op = N0.getOperand(i);
if (Op.isUndef()) {
Elts.push_back(IsZext ? DAG.getConstant(0, DL, SVT) : DAG.getUNDEF(SVT));
continue;
}
SDLoc DL(Op);
// Get the constant value and if needed trunc it to the size of the type.
// Nodes like build_vector might have constants wider than the scalar type.
APInt C = cast<ConstantSDNode>(Op)->getAPIntValue().zextOrTrunc(EVTBits);
if (Opcode == ISD::SIGN_EXTEND || Opcode == ISD::SIGN_EXTEND_VECTOR_INREG)
Elts.push_back(DAG.getConstant(C.sext(VTBits), DL, SVT));
else
Elts.push_back(DAG.getConstant(C.zext(VTBits), DL, SVT));
}
return DAG.getBuildVector(VT, DL, Elts);
}
// ExtendUsesToFormExtLoad - Trying to extend uses of a load to enable this:
// "fold ({s|z|a}ext (load x)) -> ({s|z|a}ext (truncate ({s|z|a}extload x)))"
// transformation. Returns true if extension are possible and the above
// mentioned transformation is profitable.
static bool ExtendUsesToFormExtLoad(EVT VT, SDNode *N, SDValue N0,
unsigned ExtOpc,
SmallVectorImpl<SDNode *> &ExtendNodes,
const TargetLowering &TLI) {
bool HasCopyToRegUses = false;
bool isTruncFree = TLI.isTruncateFree(VT, N0.getValueType());
for (SDNode::use_iterator UI = N0->use_begin(), UE = N0->use_end(); UI != UE;
++UI) {
SDNode *User = *UI;
if (User == N)
continue;
if (UI.getUse().getResNo() != N0.getResNo())
continue;
// FIXME: Only extend SETCC N, N and SETCC N, c for now.
if (ExtOpc != ISD::ANY_EXTEND && User->getOpcode() == ISD::SETCC) {
ISD::CondCode CC = cast<CondCodeSDNode>(User->getOperand(2))->get();
if (ExtOpc == ISD::ZERO_EXTEND && ISD::isSignedIntSetCC(CC))
// Sign bits will be lost after a zext.
return false;
bool Add = false;
for (unsigned i = 0; i != 2; ++i) {
SDValue UseOp = User->getOperand(i);
if (UseOp == N0)
continue;
if (!isa<ConstantSDNode>(UseOp))
return false;
Add = true;
}
if (Add)
ExtendNodes.push_back(User);
continue;
}
// If truncates aren't free and there are users we can't
// extend, it isn't worthwhile.
if (!isTruncFree)
return false;
// Remember if this value is live-out.
if (User->getOpcode() == ISD::CopyToReg)
HasCopyToRegUses = true;
}
if (HasCopyToRegUses) {
bool BothLiveOut = false;
for (SDNode::use_iterator UI = N->use_begin(), UE = N->use_end();
UI != UE; ++UI) {
SDUse &Use = UI.getUse();
if (Use.getResNo() == 0 && Use.getUser()->getOpcode() == ISD::CopyToReg) {
BothLiveOut = true;
break;
}
}
if (BothLiveOut)
// Both unextended and extended values are live out. There had better be
// a good reason for the transformation.
return ExtendNodes.size();
}
return true;
}
void DAGCombiner::ExtendSetCCUses(const SmallVectorImpl<SDNode *> &SetCCs,
SDValue OrigLoad, SDValue ExtLoad,
ISD::NodeType ExtType) {
// Extend SetCC uses if necessary.
SDLoc DL(ExtLoad);
for (SDNode *SetCC : SetCCs) {
SmallVector<SDValue, 4> Ops;
for (unsigned j = 0; j != 2; ++j) {
SDValue SOp = SetCC->getOperand(j);
if (SOp == OrigLoad)
Ops.push_back(ExtLoad);
else
Ops.push_back(DAG.getNode(ExtType, DL, ExtLoad->getValueType(0), SOp));
}
Ops.push_back(SetCC->getOperand(2));
CombineTo(SetCC, DAG.getNode(ISD::SETCC, DL, SetCC->getValueType(0), Ops));
}
}
// FIXME: Bring more similar combines here, common to sext/zext (maybe aext?).
SDValue DAGCombiner::CombineExtLoad(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT DstVT = N->getValueType(0);
EVT SrcVT = N0.getValueType();
assert((N->getOpcode() == ISD::SIGN_EXTEND ||
N->getOpcode() == ISD::ZERO_EXTEND) &&
"Unexpected node type (not an extend)!");
// fold (sext (load x)) to multiple smaller sextloads; same for zext.
// For example, on a target with legal v4i32, but illegal v8i32, turn:
// (v8i32 (sext (v8i16 (load x))))
// into:
// (v8i32 (concat_vectors (v4i32 (sextload x)),
// (v4i32 (sextload (x + 16)))))
// Where uses of the original load, i.e.:
// (v8i16 (load x))
// are replaced with:
// (v8i16 (truncate
// (v8i32 (concat_vectors (v4i32 (sextload x)),
// (v4i32 (sextload (x + 16)))))))
//
// This combine is only applicable to illegal, but splittable, vectors.
// All legal types, and illegal non-vector types, are handled elsewhere.
// This combine is controlled by TargetLowering::isVectorLoadExtDesirable.
//
if (N0->getOpcode() != ISD::LOAD)
return SDValue();
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
if (!ISD::isNON_EXTLoad(LN0) || !ISD::isUNINDEXEDLoad(LN0) ||
!N0.hasOneUse() || !LN0->isSimple() ||
!DstVT.isVector() || !DstVT.isPow2VectorType() ||
!TLI.isVectorLoadExtDesirable(SDValue(N, 0)))
return SDValue();
SmallVector<SDNode *, 4> SetCCs;
if (!ExtendUsesToFormExtLoad(DstVT, N, N0, N->getOpcode(), SetCCs, TLI))
return SDValue();
ISD::LoadExtType ExtType =
N->getOpcode() == ISD::SIGN_EXTEND ? ISD::SEXTLOAD : ISD::ZEXTLOAD;
// Try to split the vector types to get down to legal types.
EVT SplitSrcVT = SrcVT;
EVT SplitDstVT = DstVT;
while (!TLI.isLoadExtLegalOrCustom(ExtType, SplitDstVT, SplitSrcVT) &&
SplitSrcVT.getVectorNumElements() > 1) {
SplitDstVT = DAG.GetSplitDestVTs(SplitDstVT).first;
SplitSrcVT = DAG.GetSplitDestVTs(SplitSrcVT).first;
}
if (!TLI.isLoadExtLegalOrCustom(ExtType, SplitDstVT, SplitSrcVT))
return SDValue();
assert(!DstVT.isScalableVector() && "Unexpected scalable vector type");
SDLoc DL(N);
const unsigned NumSplits =
DstVT.getVectorNumElements() / SplitDstVT.getVectorNumElements();
const unsigned Stride = SplitSrcVT.getStoreSize();
SmallVector<SDValue, 4> Loads;
SmallVector<SDValue, 4> Chains;
SDValue BasePtr = LN0->getBasePtr();
for (unsigned Idx = 0; Idx < NumSplits; Idx++) {
const unsigned Offset = Idx * Stride;
const Align Align = commonAlignment(LN0->getAlign(), Offset);
SDValue SplitLoad = DAG.getExtLoad(
ExtType, SDLoc(LN0), SplitDstVT, LN0->getChain(), BasePtr,
LN0->getPointerInfo().getWithOffset(Offset), SplitSrcVT, Align,
LN0->getMemOperand()->getFlags(), LN0->getAAInfo());
BasePtr = DAG.getMemBasePlusOffset(BasePtr, TypeSize::Fixed(Stride), DL);
Loads.push_back(SplitLoad.getValue(0));
Chains.push_back(SplitLoad.getValue(1));
}
SDValue NewChain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, Chains);
SDValue NewValue = DAG.getNode(ISD::CONCAT_VECTORS, DL, DstVT, Loads);
// Simplify TF.
AddToWorklist(NewChain.getNode());
CombineTo(N, NewValue);
// Replace uses of the original load (before extension)
// with a truncate of the concatenated sextloaded vectors.
SDValue Trunc =
DAG.getNode(ISD::TRUNCATE, SDLoc(N0), N0.getValueType(), NewValue);
ExtendSetCCUses(SetCCs, N0, NewValue, (ISD::NodeType)N->getOpcode());
CombineTo(N0.getNode(), Trunc, NewChain);
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
// fold (zext (and/or/xor (shl/shr (load x), cst), cst)) ->
// (and/or/xor (shl/shr (zextload x), (zext cst)), (zext cst))
SDValue DAGCombiner::CombineZExtLogicopShiftLoad(SDNode *N) {
assert(N->getOpcode() == ISD::ZERO_EXTEND);
EVT VT = N->getValueType(0);
EVT OrigVT = N->getOperand(0).getValueType();
if (TLI.isZExtFree(OrigVT, VT))
return SDValue();
// and/or/xor
SDValue N0 = N->getOperand(0);
if (!(N0.getOpcode() == ISD::AND || N0.getOpcode() == ISD::OR ||
N0.getOpcode() == ISD::XOR) ||
N0.getOperand(1).getOpcode() != ISD::Constant ||
(LegalOperations && !TLI.isOperationLegal(N0.getOpcode(), VT)))
return SDValue();
// shl/shr
SDValue N1 = N0->getOperand(0);
if (!(N1.getOpcode() == ISD::SHL || N1.getOpcode() == ISD::SRL) ||
N1.getOperand(1).getOpcode() != ISD::Constant ||
(LegalOperations && !TLI.isOperationLegal(N1.getOpcode(), VT)))
return SDValue();
// load
if (!isa<LoadSDNode>(N1.getOperand(0)))
return SDValue();
LoadSDNode *Load = cast<LoadSDNode>(N1.getOperand(0));
EVT MemVT = Load->getMemoryVT();
if (!TLI.isLoadExtLegal(ISD::ZEXTLOAD, VT, MemVT) ||
Load->getExtensionType() == ISD::SEXTLOAD || Load->isIndexed())
return SDValue();
// If the shift op is SHL, the logic op must be AND, otherwise the result
// will be wrong.
if (N1.getOpcode() == ISD::SHL && N0.getOpcode() != ISD::AND)
return SDValue();
if (!N0.hasOneUse() || !N1.hasOneUse())
return SDValue();
SmallVector<SDNode*, 4> SetCCs;
if (!ExtendUsesToFormExtLoad(VT, N1.getNode(), N1.getOperand(0),
ISD::ZERO_EXTEND, SetCCs, TLI))
return SDValue();
// Actually do the transformation.
SDValue ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, SDLoc(Load), VT,
Load->getChain(), Load->getBasePtr(),
Load->getMemoryVT(), Load->getMemOperand());
SDLoc DL1(N1);
SDValue Shift = DAG.getNode(N1.getOpcode(), DL1, VT, ExtLoad,
N1.getOperand(1));
APInt Mask = N0.getConstantOperandAPInt(1).zext(VT.getSizeInBits());
SDLoc DL0(N0);
SDValue And = DAG.getNode(N0.getOpcode(), DL0, VT, Shift,
DAG.getConstant(Mask, DL0, VT));
ExtendSetCCUses(SetCCs, N1.getOperand(0), ExtLoad, ISD::ZERO_EXTEND);
CombineTo(N, And);
if (SDValue(Load, 0).hasOneUse()) {
DAG.ReplaceAllUsesOfValueWith(SDValue(Load, 1), ExtLoad.getValue(1));
} else {
SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(Load),
Load->getValueType(0), ExtLoad);
CombineTo(Load, Trunc, ExtLoad.getValue(1));
}
// N0 is dead at this point.
recursivelyDeleteUnusedNodes(N0.getNode());
return SDValue(N,0); // Return N so it doesn't get rechecked!
}
/// If we're narrowing or widening the result of a vector select and the final
/// size is the same size as a setcc (compare) feeding the select, then try to
/// apply the cast operation to the select's operands because matching vector
/// sizes for a select condition and other operands should be more efficient.
SDValue DAGCombiner::matchVSelectOpSizesWithSetCC(SDNode *Cast) {
unsigned CastOpcode = Cast->getOpcode();
assert((CastOpcode == ISD::SIGN_EXTEND || CastOpcode == ISD::ZERO_EXTEND ||
CastOpcode == ISD::TRUNCATE || CastOpcode == ISD::FP_EXTEND ||
CastOpcode == ISD::FP_ROUND) &&
"Unexpected opcode for vector select narrowing/widening");
// We only do this transform before legal ops because the pattern may be
// obfuscated by target-specific operations after legalization. Do not create
// an illegal select op, however, because that may be difficult to lower.
EVT VT = Cast->getValueType(0);
if (LegalOperations || !TLI.isOperationLegalOrCustom(ISD::VSELECT, VT))
return SDValue();
SDValue VSel = Cast->getOperand(0);
if (VSel.getOpcode() != ISD::VSELECT || !VSel.hasOneUse() ||
VSel.getOperand(0).getOpcode() != ISD::SETCC)
return SDValue();
// Does the setcc have the same vector size as the casted select?
SDValue SetCC = VSel.getOperand(0);
EVT SetCCVT = getSetCCResultType(SetCC.getOperand(0).getValueType());
if (SetCCVT.getSizeInBits() != VT.getSizeInBits())
return SDValue();
// cast (vsel (setcc X), A, B) --> vsel (setcc X), (cast A), (cast B)
SDValue A = VSel.getOperand(1);
SDValue B = VSel.getOperand(2);
SDValue CastA, CastB;
SDLoc DL(Cast);
if (CastOpcode == ISD::FP_ROUND) {
// FP_ROUND (fptrunc) has an extra flag operand to pass along.
CastA = DAG.getNode(CastOpcode, DL, VT, A, Cast->getOperand(1));
CastB = DAG.getNode(CastOpcode, DL, VT, B, Cast->getOperand(1));
} else {
CastA = DAG.getNode(CastOpcode, DL, VT, A);
CastB = DAG.getNode(CastOpcode, DL, VT, B);
}
return DAG.getNode(ISD::VSELECT, DL, VT, SetCC, CastA, CastB);
}
// fold ([s|z]ext ([s|z]extload x)) -> ([s|z]ext (truncate ([s|z]extload x)))
// fold ([s|z]ext ( extload x)) -> ([s|z]ext (truncate ([s|z]extload x)))
static SDValue tryToFoldExtOfExtload(SelectionDAG &DAG, DAGCombiner &Combiner,
const TargetLowering &TLI, EVT VT,
bool LegalOperations, SDNode *N,
SDValue N0, ISD::LoadExtType ExtLoadType) {
SDNode *N0Node = N0.getNode();
bool isAExtLoad = (ExtLoadType == ISD::SEXTLOAD) ? ISD::isSEXTLoad(N0Node)
: ISD::isZEXTLoad(N0Node);
if ((!isAExtLoad && !ISD::isEXTLoad(N0Node)) ||
!ISD::isUNINDEXEDLoad(N0Node) || !N0.hasOneUse())
return SDValue();
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
EVT MemVT = LN0->getMemoryVT();
if ((LegalOperations || !LN0->isSimple() ||
VT.isVector()) &&
!TLI.isLoadExtLegal(ExtLoadType, VT, MemVT))
return SDValue();
SDValue ExtLoad =
DAG.getExtLoad(ExtLoadType, SDLoc(LN0), VT, LN0->getChain(),
LN0->getBasePtr(), MemVT, LN0->getMemOperand());
Combiner.CombineTo(N, ExtLoad);
DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
if (LN0->use_empty())
Combiner.recursivelyDeleteUnusedNodes(LN0);
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
// fold ([s|z]ext (load x)) -> ([s|z]ext (truncate ([s|z]extload x)))
// Only generate vector extloads when 1) they're legal, and 2) they are
// deemed desirable by the target.
static SDValue tryToFoldExtOfLoad(SelectionDAG &DAG, DAGCombiner &Combiner,
const TargetLowering &TLI, EVT VT,
bool LegalOperations, SDNode *N, SDValue N0,
ISD::LoadExtType ExtLoadType,
ISD::NodeType ExtOpc) {
// TODO: isFixedLengthVector() should be removed and any negative effects on
// code generation being the result of that target's implementation of
// isVectorLoadExtDesirable().
if (!ISD::isNON_EXTLoad(N0.getNode()) ||
!ISD::isUNINDEXEDLoad(N0.getNode()) ||
((LegalOperations || VT.isFixedLengthVector() ||
!cast<LoadSDNode>(N0)->isSimple()) &&
!TLI.isLoadExtLegal(ExtLoadType, VT, N0.getValueType())))
return {};
bool DoXform = true;
SmallVector<SDNode *, 4> SetCCs;
if (!N0.hasOneUse())
DoXform = ExtendUsesToFormExtLoad(VT, N, N0, ExtOpc, SetCCs, TLI);
if (VT.isVector())
DoXform &= TLI.isVectorLoadExtDesirable(SDValue(N, 0));
if (!DoXform)
return {};
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
SDValue ExtLoad = DAG.getExtLoad(ExtLoadType, SDLoc(LN0), VT, LN0->getChain(),
LN0->getBasePtr(), N0.getValueType(),
LN0->getMemOperand());
Combiner.ExtendSetCCUses(SetCCs, N0, ExtLoad, ExtOpc);
// If the load value is used only by N, replace it via CombineTo N.
bool NoReplaceTrunc = SDValue(LN0, 0).hasOneUse();
Combiner.CombineTo(N, ExtLoad);
if (NoReplaceTrunc) {
DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
Combiner.recursivelyDeleteUnusedNodes(LN0);
} else {
SDValue Trunc =
DAG.getNode(ISD::TRUNCATE, SDLoc(N0), N0.getValueType(), ExtLoad);
Combiner.CombineTo(LN0, Trunc, ExtLoad.getValue(1));
}
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
static SDValue tryToFoldExtOfMaskedLoad(SelectionDAG &DAG,
const TargetLowering &TLI, EVT VT,
SDNode *N, SDValue N0,
ISD::LoadExtType ExtLoadType,
ISD::NodeType ExtOpc) {
if (!N0.hasOneUse())
return SDValue();
MaskedLoadSDNode *Ld = dyn_cast<MaskedLoadSDNode>(N0);
if (!Ld || Ld->getExtensionType() != ISD::NON_EXTLOAD)
return SDValue();
if (!TLI.isLoadExtLegalOrCustom(ExtLoadType, VT, Ld->getValueType(0)))
return SDValue();
if (!TLI.isVectorLoadExtDesirable(SDValue(N, 0)))
return SDValue();
SDLoc dl(Ld);
SDValue PassThru = DAG.getNode(ExtOpc, dl, VT, Ld->getPassThru());
SDValue NewLoad = DAG.getMaskedLoad(
VT, dl, Ld->getChain(), Ld->getBasePtr(), Ld->getOffset(), Ld->getMask(),
PassThru, Ld->getMemoryVT(), Ld->getMemOperand(), Ld->getAddressingMode(),
ExtLoadType, Ld->isExpandingLoad());
DAG.ReplaceAllUsesOfValueWith(SDValue(Ld, 1), SDValue(NewLoad.getNode(), 1));
return NewLoad;
}
static SDValue foldExtendedSignBitTest(SDNode *N, SelectionDAG &DAG,
bool LegalOperations) {
assert((N->getOpcode() == ISD::SIGN_EXTEND ||
N->getOpcode() == ISD::ZERO_EXTEND) && "Expected sext or zext");
SDValue SetCC = N->getOperand(0);
if (LegalOperations || SetCC.getOpcode() != ISD::SETCC ||
!SetCC.hasOneUse() || SetCC.getValueType() != MVT::i1)
return SDValue();
SDValue X = SetCC.getOperand(0);
SDValue Ones = SetCC.getOperand(1);
ISD::CondCode CC = cast<CondCodeSDNode>(SetCC.getOperand(2))->get();
EVT VT = N->getValueType(0);
EVT XVT = X.getValueType();
// setge X, C is canonicalized to setgt, so we do not need to match that
// pattern. The setlt sibling is folded in SimplifySelectCC() because it does
// not require the 'not' op.
if (CC == ISD::SETGT && isAllOnesConstant(Ones) && VT == XVT) {
// Invert and smear/shift the sign bit:
// sext i1 (setgt iN X, -1) --> sra (not X), (N - 1)
// zext i1 (setgt iN X, -1) --> srl (not X), (N - 1)
SDLoc DL(N);
unsigned ShCt = VT.getSizeInBits() - 1;
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
if (!TLI.shouldAvoidTransformToShift(VT, ShCt)) {
SDValue NotX = DAG.getNOT(DL, X, VT);
SDValue ShiftAmount = DAG.getConstant(ShCt, DL, VT);
auto ShiftOpcode =
N->getOpcode() == ISD::SIGN_EXTEND ? ISD::SRA : ISD::SRL;
return DAG.getNode(ShiftOpcode, DL, VT, NotX, ShiftAmount);
}
}
return SDValue();
}
SDValue DAGCombiner::foldSextSetcc(SDNode *N) {
SDValue N0 = N->getOperand(0);
if (N0.getOpcode() != ISD::SETCC)
return SDValue();
SDValue N00 = N0.getOperand(0);
SDValue N01 = N0.getOperand(1);
ISD::CondCode CC = cast<CondCodeSDNode>(N0.getOperand(2))->get();
EVT VT = N->getValueType(0);
EVT N00VT = N00.getValueType();
SDLoc DL(N);
// On some architectures (such as SSE/NEON/etc) the SETCC result type is
// the same size as the compared operands. Try to optimize sext(setcc())
// if this is the case.
if (VT.isVector() && !LegalOperations &&
TLI.getBooleanContents(N00VT) ==
TargetLowering::ZeroOrNegativeOneBooleanContent) {
EVT SVT = getSetCCResultType(N00VT);
// If we already have the desired type, don't change it.
if (SVT != N0.getValueType()) {
// We know that the # elements of the results is the same as the
// # elements of the compare (and the # elements of the compare result
// for that matter). Check to see that they are the same size. If so,
// we know that the element size of the sext'd result matches the
// element size of the compare operands.
if (VT.getSizeInBits() == SVT.getSizeInBits())
return DAG.getSetCC(DL, VT, N00, N01, CC);
// If the desired elements are smaller or larger than the source
// elements, we can use a matching integer vector type and then
// truncate/sign extend.
EVT MatchingVecType = N00VT.changeVectorElementTypeToInteger();
if (SVT == MatchingVecType) {
SDValue VsetCC = DAG.getSetCC(DL, MatchingVecType, N00, N01, CC);
return DAG.getSExtOrTrunc(VsetCC, DL, VT);
}
}
// Try to eliminate the sext of a setcc by zexting the compare operands.
if (N0.hasOneUse() && TLI.isOperationLegalOrCustom(ISD::SETCC, VT) &&
!TLI.isOperationLegalOrCustom(ISD::SETCC, SVT)) {
bool IsSignedCmp = ISD::isSignedIntSetCC(CC);
unsigned LoadOpcode = IsSignedCmp ? ISD::SEXTLOAD : ISD::ZEXTLOAD;
unsigned ExtOpcode = IsSignedCmp ? ISD::SIGN_EXTEND : ISD::ZERO_EXTEND;
// We have an unsupported narrow vector compare op that would be legal
// if extended to the destination type. See if the compare operands
// can be freely extended to the destination type.
auto IsFreeToExtend = [&](SDValue V) {
if (isConstantOrConstantVector(V, /*NoOpaques*/ true))
return true;
// Match a simple, non-extended load that can be converted to a
// legal {z/s}ext-load.
// TODO: Allow widening of an existing {z/s}ext-load?
if (!(ISD::isNON_EXTLoad(V.getNode()) &&
ISD::isUNINDEXEDLoad(V.getNode()) &&
cast<LoadSDNode>(V)->isSimple() &&
TLI.isLoadExtLegal(LoadOpcode, VT, V.getValueType())))
return false;
// Non-chain users of this value must either be the setcc in this
// sequence or extends that can be folded into the new {z/s}ext-load.
for (SDNode::use_iterator UI = V->use_begin(), UE = V->use_end();
UI != UE; ++UI) {
// Skip uses of the chain and the setcc.
SDNode *User = *UI;
if (UI.getUse().getResNo() != 0 || User == N0.getNode())
continue;
// Extra users must have exactly the same cast we are about to create.
// TODO: This restriction could be eased if ExtendUsesToFormExtLoad()
// is enhanced similarly.
if (User->getOpcode() != ExtOpcode || User->getValueType(0) != VT)
return false;
}
return true;
};
if (IsFreeToExtend(N00) && IsFreeToExtend(N01)) {
SDValue Ext0 = DAG.getNode(ExtOpcode, DL, VT, N00);
SDValue Ext1 = DAG.getNode(ExtOpcode, DL, VT, N01);
return DAG.getSetCC(DL, VT, Ext0, Ext1, CC);
}
}
}
// sext(setcc x, y, cc) -> (select (setcc x, y, cc), T, 0)
// Here, T can be 1 or -1, depending on the type of the setcc and
// getBooleanContents().
unsigned SetCCWidth = N0.getScalarValueSizeInBits();
// To determine the "true" side of the select, we need to know the high bit
// of the value returned by the setcc if it evaluates to true.
// If the type of the setcc is i1, then the true case of the select is just
// sext(i1 1), that is, -1.
// If the type of the setcc is larger (say, i8) then the value of the high
// bit depends on getBooleanContents(), so ask TLI for a real "true" value
// of the appropriate width.
SDValue ExtTrueVal = (SetCCWidth == 1)
? DAG.getAllOnesConstant(DL, VT)
: DAG.getBoolConstant(true, DL, VT, N00VT);
SDValue Zero = DAG.getConstant(0, DL, VT);
if (SDValue SCC = SimplifySelectCC(DL, N00, N01, ExtTrueVal, Zero, CC, true))
return SCC;
if (!VT.isVector() && !TLI.convertSelectOfConstantsToMath(VT)) {
EVT SetCCVT = getSetCCResultType(N00VT);
// Don't do this transform for i1 because there's a select transform
// that would reverse it.
// TODO: We should not do this transform at all without a target hook
// because a sext is likely cheaper than a select?
if (SetCCVT.getScalarSizeInBits() != 1 &&
(!LegalOperations || TLI.isOperationLegal(ISD::SETCC, N00VT))) {
SDValue SetCC = DAG.getSetCC(DL, SetCCVT, N00, N01, CC);
return DAG.getSelect(DL, VT, SetCC, ExtTrueVal, Zero);
}
}
return SDValue();
}
SDValue DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
SDLoc DL(N);
// sext(undef) = 0 because the top bit will all be the same.
if (N0.isUndef())
return DAG.getConstant(0, DL, VT);
if (SDValue Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes))
return Res;
// fold (sext (sext x)) -> (sext x)
// fold (sext (aext x)) -> (sext x)
if (N0.getOpcode() == ISD::SIGN_EXTEND || N0.getOpcode() == ISD::ANY_EXTEND)
return DAG.getNode(ISD::SIGN_EXTEND, DL, VT, N0.getOperand(0));
if (N0.getOpcode() == ISD::TRUNCATE) {
// fold (sext (truncate (load x))) -> (sext (smaller load x))
// fold (sext (truncate (srl (load x), c))) -> (sext (smaller load (x+c/n)))
if (SDValue NarrowLoad = reduceLoadWidth(N0.getNode())) {
SDNode *oye = N0.getOperand(0).getNode();
if (NarrowLoad.getNode() != N0.getNode()) {
CombineTo(N0.getNode(), NarrowLoad);
// CombineTo deleted the truncate, if needed, but not what's under it.
AddToWorklist(oye);
}
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
// See if the value being truncated is already sign extended. If so, just
// eliminate the trunc/sext pair.
SDValue Op = N0.getOperand(0);
unsigned OpBits = Op.getScalarValueSizeInBits();
unsigned MidBits = N0.getScalarValueSizeInBits();
unsigned DestBits = VT.getScalarSizeInBits();
unsigned NumSignBits = DAG.ComputeNumSignBits(Op);
if (OpBits == DestBits) {
// Op is i32, Mid is i8, and Dest is i32. If Op has more than 24 sign
// bits, it is already ready.
if (NumSignBits > DestBits-MidBits)
return Op;
} else if (OpBits < DestBits) {
// Op is i32, Mid is i8, and Dest is i64. If Op has more than 24 sign
// bits, just sext from i32.
if (NumSignBits > OpBits-MidBits)
return DAG.getNode(ISD::SIGN_EXTEND, DL, VT, Op);
} else {
// Op is i64, Mid is i8, and Dest is i32. If Op has more than 56 sign
// bits, just truncate to i32.
if (NumSignBits > OpBits-MidBits)
return DAG.getNode(ISD::TRUNCATE, DL, VT, Op);
}
// fold (sext (truncate x)) -> (sextinreg x).
if (!LegalOperations || TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG,
N0.getValueType())) {
if (OpBits < DestBits)
Op = DAG.getNode(ISD::ANY_EXTEND, SDLoc(N0), VT, Op);
else if (OpBits > DestBits)
Op = DAG.getNode(ISD::TRUNCATE, SDLoc(N0), VT, Op);
return DAG.getNode(ISD::SIGN_EXTEND_INREG, DL, VT, Op,
DAG.getValueType(N0.getValueType()));
}
}
// Try to simplify (sext (load x)).
if (SDValue foldedExt =
tryToFoldExtOfLoad(DAG, *this, TLI, VT, LegalOperations, N, N0,
ISD::SEXTLOAD, ISD::SIGN_EXTEND))
return foldedExt;
if (SDValue foldedExt =
tryToFoldExtOfMaskedLoad(DAG, TLI, VT, N, N0, ISD::SEXTLOAD,
ISD::SIGN_EXTEND))
return foldedExt;
// fold (sext (load x)) to multiple smaller sextloads.
// Only on illegal but splittable vectors.
if (SDValue ExtLoad = CombineExtLoad(N))
return ExtLoad;
// Try to simplify (sext (sextload x)).
if (SDValue foldedExt = tryToFoldExtOfExtload(
DAG, *this, TLI, VT, LegalOperations, N, N0, ISD::SEXTLOAD))
return foldedExt;
// fold (sext (and/or/xor (load x), cst)) ->
// (and/or/xor (sextload x), (sext cst))
if ((N0.getOpcode() == ISD::AND || N0.getOpcode() == ISD::OR ||
N0.getOpcode() == ISD::XOR) &&
isa<LoadSDNode>(N0.getOperand(0)) &&
N0.getOperand(1).getOpcode() == ISD::Constant &&
(!LegalOperations && TLI.isOperationLegal(N0.getOpcode(), VT))) {
LoadSDNode *LN00 = cast<LoadSDNode>(N0.getOperand(0));
EVT MemVT = LN00->getMemoryVT();
if (TLI.isLoadExtLegal(ISD::SEXTLOAD, VT, MemVT) &&
LN00->getExtensionType() != ISD::ZEXTLOAD && LN00->isUnindexed()) {
SmallVector<SDNode*, 4> SetCCs;
bool DoXform = ExtendUsesToFormExtLoad(VT, N0.getNode(), N0.getOperand(0),
ISD::SIGN_EXTEND, SetCCs, TLI);
if (DoXform) {
SDValue ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, SDLoc(LN00), VT,
LN00->getChain(), LN00->getBasePtr(),
LN00->getMemoryVT(),
LN00->getMemOperand());
APInt Mask = N0.getConstantOperandAPInt(1).sext(VT.getSizeInBits());
SDValue And = DAG.getNode(N0.getOpcode(), DL, VT,
ExtLoad, DAG.getConstant(Mask, DL, VT));
ExtendSetCCUses(SetCCs, N0.getOperand(0), ExtLoad, ISD::SIGN_EXTEND);
bool NoReplaceTruncAnd = !N0.hasOneUse();
bool NoReplaceTrunc = SDValue(LN00, 0).hasOneUse();
CombineTo(N, And);
// If N0 has multiple uses, change other uses as well.
if (NoReplaceTruncAnd) {
SDValue TruncAnd =
DAG.getNode(ISD::TRUNCATE, DL, N0.getValueType(), And);
CombineTo(N0.getNode(), TruncAnd);
}
if (NoReplaceTrunc) {
DAG.ReplaceAllUsesOfValueWith(SDValue(LN00, 1), ExtLoad.getValue(1));
} else {
SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(LN00),
LN00->getValueType(0), ExtLoad);
CombineTo(LN00, Trunc, ExtLoad.getValue(1));
}
return SDValue(N,0); // Return N so it doesn't get rechecked!
}
}
}
if (SDValue V = foldExtendedSignBitTest(N, DAG, LegalOperations))
return V;
if (SDValue V = foldSextSetcc(N))
return V;
// fold (sext x) -> (zext x) if the sign bit is known zero.
if ((!LegalOperations || TLI.isOperationLegal(ISD::ZERO_EXTEND, VT)) &&
DAG.SignBitIsZero(N0))
return DAG.getNode(ISD::ZERO_EXTEND, DL, VT, N0);
if (SDValue NewVSel = matchVSelectOpSizesWithSetCC(N))
return NewVSel;
// Eliminate this sign extend by doing a negation in the destination type:
// sext i32 (0 - (zext i8 X to i32)) to i64 --> 0 - (zext i8 X to i64)
if (N0.getOpcode() == ISD::SUB && N0.hasOneUse() &&
isNullOrNullSplat(N0.getOperand(0)) &&
N0.getOperand(1).getOpcode() == ISD::ZERO_EXTEND &&
TLI.isOperationLegalOrCustom(ISD::SUB, VT)) {
SDValue Zext = DAG.getZExtOrTrunc(N0.getOperand(1).getOperand(0), DL, VT);
return DAG.getNode(ISD::SUB, DL, VT, DAG.getConstant(0, DL, VT), Zext);
}
// Eliminate this sign extend by doing a decrement in the destination type:
// sext i32 ((zext i8 X to i32) + (-1)) to i64 --> (zext i8 X to i64) + (-1)
if (N0.getOpcode() == ISD::ADD && N0.hasOneUse() &&
isAllOnesOrAllOnesSplat(N0.getOperand(1)) &&
N0.getOperand(0).getOpcode() == ISD::ZERO_EXTEND &&
TLI.isOperationLegalOrCustom(ISD::ADD, VT)) {
SDValue Zext = DAG.getZExtOrTrunc(N0.getOperand(0).getOperand(0), DL, VT);
return DAG.getNode(ISD::ADD, DL, VT, Zext, DAG.getAllOnesConstant(DL, VT));
}
// fold sext (not i1 X) -> add (zext i1 X), -1
// TODO: This could be extended to handle bool vectors.
if (N0.getValueType() == MVT::i1 && isBitwiseNot(N0) && N0.hasOneUse() &&
(!LegalOperations || (TLI.isOperationLegal(ISD::ZERO_EXTEND, VT) &&
TLI.isOperationLegal(ISD::ADD, VT)))) {
// If we can eliminate the 'not', the sext form should be better
if (SDValue NewXor = visitXOR(N0.getNode())) {
// Returning N0 is a form of in-visit replacement that may have
// invalidated N0.
if (NewXor.getNode() == N0.getNode()) {
// Return SDValue here as the xor should have already been replaced in
// this sext.
return SDValue();
}
// Return a new sext with the new xor.
return DAG.getNode(ISD::SIGN_EXTEND, DL, VT, NewXor);
}
SDValue Zext = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, N0.getOperand(0));
return DAG.getNode(ISD::ADD, DL, VT, Zext, DAG.getAllOnesConstant(DL, VT));
}
if (SDValue Res = tryToFoldExtendSelectLoad(N, TLI, DAG))
return Res;
return SDValue();
}
// isTruncateOf - If N is a truncate of some other value, return true, record
// the value being truncated in Op and which of Op's bits are zero/one in Known.
// This function computes KnownBits to avoid a duplicated call to
// computeKnownBits in the caller.
static bool isTruncateOf(SelectionDAG &DAG, SDValue N, SDValue &Op,
KnownBits &Known) {
if (N->getOpcode() == ISD::TRUNCATE) {
Op = N->getOperand(0);
Known = DAG.computeKnownBits(Op);
return true;
}
if (N.getOpcode() != ISD::SETCC ||
N.getValueType().getScalarType() != MVT::i1 ||
cast<CondCodeSDNode>(N.getOperand(2))->get() != ISD::SETNE)
return false;
SDValue Op0 = N->getOperand(0);
SDValue Op1 = N->getOperand(1);
assert(Op0.getValueType() == Op1.getValueType());
if (isNullOrNullSplat(Op0))
Op = Op1;
else if (isNullOrNullSplat(Op1))
Op = Op0;
else
return false;
Known = DAG.computeKnownBits(Op);
return (Known.Zero | 1).isAllOnes();
}
/// Given an extending node with a pop-count operand, if the target does not
/// support a pop-count in the narrow source type but does support it in the
/// destination type, widen the pop-count to the destination type.
static SDValue widenCtPop(SDNode *Extend, SelectionDAG &DAG) {
assert((Extend->getOpcode() == ISD::ZERO_EXTEND ||
Extend->getOpcode() == ISD::ANY_EXTEND) && "Expected extend op");
SDValue CtPop = Extend->getOperand(0);
if (CtPop.getOpcode() != ISD::CTPOP || !CtPop.hasOneUse())
return SDValue();
EVT VT = Extend->getValueType(0);
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
if (TLI.isOperationLegalOrCustom(ISD::CTPOP, CtPop.getValueType()) ||
!TLI.isOperationLegalOrCustom(ISD::CTPOP, VT))
return SDValue();
// zext (ctpop X) --> ctpop (zext X)
SDLoc DL(Extend);
SDValue NewZext = DAG.getZExtOrTrunc(CtPop.getOperand(0), DL, VT);
return DAG.getNode(ISD::CTPOP, DL, VT, NewZext);
}
SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// zext(undef) = 0
if (N0.isUndef())
return DAG.getConstant(0, SDLoc(N), VT);
if (SDValue Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes))
return Res;
// fold (zext (zext x)) -> (zext x)
// fold (zext (aext x)) -> (zext x)
if (N0.getOpcode() == ISD::ZERO_EXTEND || N0.getOpcode() == ISD::ANY_EXTEND)
return DAG.getNode(ISD::ZERO_EXTEND, SDLoc(N), VT,
N0.getOperand(0));
// fold (zext (truncate x)) -> (zext x) or
// (zext (truncate x)) -> (truncate x)
// This is valid when the truncated bits of x are already zero.
SDValue Op;
KnownBits Known;
if (isTruncateOf(DAG, N0, Op, Known)) {
APInt TruncatedBits =
(Op.getScalarValueSizeInBits() == N0.getScalarValueSizeInBits()) ?
APInt(Op.getScalarValueSizeInBits(), 0) :
APInt::getBitsSet(Op.getScalarValueSizeInBits(),
N0.getScalarValueSizeInBits(),
std::min(Op.getScalarValueSizeInBits(),
VT.getScalarSizeInBits()));
if (TruncatedBits.isSubsetOf(Known.Zero))
return DAG.getZExtOrTrunc(Op, SDLoc(N), VT);
}
// fold (zext (truncate x)) -> (and x, mask)
if (N0.getOpcode() == ISD::TRUNCATE) {
// fold (zext (truncate (load x))) -> (zext (smaller load x))
// fold (zext (truncate (srl (load x), c))) -> (zext (smaller load (x+c/n)))
if (SDValue NarrowLoad = reduceLoadWidth(N0.getNode())) {
SDNode *oye = N0.getOperand(0).getNode();
if (NarrowLoad.getNode() != N0.getNode()) {
CombineTo(N0.getNode(), NarrowLoad);
// CombineTo deleted the truncate, if needed, but not what's under it.
AddToWorklist(oye);
}
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
EVT SrcVT = N0.getOperand(0).getValueType();
EVT MinVT = N0.getValueType();
// Try to mask before the extension to avoid having to generate a larger mask,
// possibly over several sub-vectors.
if (SrcVT.bitsLT(VT) && VT.isVector()) {
if (!LegalOperations || (TLI.isOperationLegal(ISD::AND, SrcVT) &&
TLI.isOperationLegal(ISD::ZERO_EXTEND, VT))) {
SDValue Op = N0.getOperand(0);
Op = DAG.getZeroExtendInReg(Op, SDLoc(N), MinVT);
AddToWorklist(Op.getNode());
SDValue ZExtOrTrunc = DAG.getZExtOrTrunc(Op, SDLoc(N), VT);
// Transfer the debug info; the new node is equivalent to N0.
DAG.transferDbgValues(N0, ZExtOrTrunc);
return ZExtOrTrunc;
}
}
if (!LegalOperations || TLI.isOperationLegal(ISD::AND, VT)) {
SDValue Op = DAG.getAnyExtOrTrunc(N0.getOperand(0), SDLoc(N), VT);
AddToWorklist(Op.getNode());
SDValue And = DAG.getZeroExtendInReg(Op, SDLoc(N), MinVT);
// We may safely transfer the debug info describing the truncate node over
// to the equivalent and operation.
DAG.transferDbgValues(N0, And);
return And;
}
}
// Fold (zext (and (trunc x), cst)) -> (and x, cst),
// if either of the casts is not free.
if (N0.getOpcode() == ISD::AND &&
N0.getOperand(0).getOpcode() == ISD::TRUNCATE &&
N0.getOperand(1).getOpcode() == ISD::Constant &&
(!TLI.isTruncateFree(N0.getOperand(0).getOperand(0).getValueType(),
N0.getValueType()) ||
!TLI.isZExtFree(N0.getValueType(), VT))) {
SDValue X = N0.getOperand(0).getOperand(0);
X = DAG.getAnyExtOrTrunc(X, SDLoc(X), VT);
APInt Mask = N0.getConstantOperandAPInt(1).zext(VT.getSizeInBits());
SDLoc DL(N);
return DAG.getNode(ISD::AND, DL, VT,
X, DAG.getConstant(Mask, DL, VT));
}
// Try to simplify (zext (load x)).
if (SDValue foldedExt =
tryToFoldExtOfLoad(DAG, *this, TLI, VT, LegalOperations, N, N0,
ISD::ZEXTLOAD, ISD::ZERO_EXTEND))
return foldedExt;
if (SDValue foldedExt =
tryToFoldExtOfMaskedLoad(DAG, TLI, VT, N, N0, ISD::ZEXTLOAD,
ISD::ZERO_EXTEND))
return foldedExt;
// fold (zext (load x)) to multiple smaller zextloads.
// Only on illegal but splittable vectors.
if (SDValue ExtLoad = CombineExtLoad(N))
return ExtLoad;
// fold (zext (and/or/xor (load x), cst)) ->
// (and/or/xor (zextload x), (zext cst))
// Unless (and (load x) cst) will match as a zextload already and has
// additional users.
if ((N0.getOpcode() == ISD::AND || N0.getOpcode() == ISD::OR ||
N0.getOpcode() == ISD::XOR) &&
isa<LoadSDNode>(N0.getOperand(0)) &&
N0.getOperand(1).getOpcode() == ISD::Constant &&
(!LegalOperations && TLI.isOperationLegal(N0.getOpcode(), VT))) {
LoadSDNode *LN00 = cast<LoadSDNode>(N0.getOperand(0));
EVT MemVT = LN00->getMemoryVT();
if (TLI.isLoadExtLegal(ISD::ZEXTLOAD, VT, MemVT) &&
LN00->getExtensionType() != ISD::SEXTLOAD && LN00->isUnindexed()) {
bool DoXform = true;
SmallVector<SDNode*, 4> SetCCs;
if (!N0.hasOneUse()) {
if (N0.getOpcode() == ISD::AND) {
auto *AndC = cast<ConstantSDNode>(N0.getOperand(1));
EVT LoadResultTy = AndC->getValueType(0);
EVT ExtVT;
if (isAndLoadExtLoad(AndC, LN00, LoadResultTy, ExtVT))
DoXform = false;
}
}
if (DoXform)
DoXform = ExtendUsesToFormExtLoad(VT, N0.getNode(), N0.getOperand(0),
ISD::ZERO_EXTEND, SetCCs, TLI);
if (DoXform) {
SDValue ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, SDLoc(LN00), VT,
LN00->getChain(), LN00->getBasePtr(),
LN00->getMemoryVT(),
LN00->getMemOperand());
APInt Mask = N0.getConstantOperandAPInt(1).zext(VT.getSizeInBits());
SDLoc DL(N);
SDValue And = DAG.getNode(N0.getOpcode(), DL, VT,
ExtLoad, DAG.getConstant(Mask, DL, VT));
ExtendSetCCUses(SetCCs, N0.getOperand(0), ExtLoad, ISD::ZERO_EXTEND);
bool NoReplaceTruncAnd = !N0.hasOneUse();
bool NoReplaceTrunc = SDValue(LN00, 0).hasOneUse();
CombineTo(N, And);
// If N0 has multiple uses, change other uses as well.
if (NoReplaceTruncAnd) {
SDValue TruncAnd =
DAG.getNode(ISD::TRUNCATE, DL, N0.getValueType(), And);
CombineTo(N0.getNode(), TruncAnd);
}
if (NoReplaceTrunc) {
DAG.ReplaceAllUsesOfValueWith(SDValue(LN00, 1), ExtLoad.getValue(1));
} else {
SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(LN00),
LN00->getValueType(0), ExtLoad);
CombineTo(LN00, Trunc, ExtLoad.getValue(1));
}
return SDValue(N,0); // Return N so it doesn't get rechecked!
}
}
}
// fold (zext (and/or/xor (shl/shr (load x), cst), cst)) ->
// (and/or/xor (shl/shr (zextload x), (zext cst)), (zext cst))
if (SDValue ZExtLoad = CombineZExtLogicopShiftLoad(N))
return ZExtLoad;
// Try to simplify (zext (zextload x)).
if (SDValue foldedExt = tryToFoldExtOfExtload(
DAG, *this, TLI, VT, LegalOperations, N, N0, ISD::ZEXTLOAD))
return foldedExt;
if (SDValue V = foldExtendedSignBitTest(N, DAG, LegalOperations))
return V;
if (N0.getOpcode() == ISD::SETCC) {
// Only do this before legalize for now.
if (!LegalOperations && VT.isVector() &&
N0.getValueType().getVectorElementType() == MVT::i1) {
EVT N00VT = N0.getOperand(0).getValueType();
if (getSetCCResultType(N00VT) == N0.getValueType())
return SDValue();
// We know that the # elements of the results is the same as the #
// elements of the compare (and the # elements of the compare result for
// that matter). Check to see that they are the same size. If so, we know
// that the element size of the sext'd result matches the element size of
// the compare operands.
SDLoc DL(N);
if (VT.getSizeInBits() == N00VT.getSizeInBits()) {
// zext(setcc) -> zext_in_reg(vsetcc) for vectors.
SDValue VSetCC = DAG.getNode(ISD::SETCC, DL, VT, N0.getOperand(0),
N0.getOperand(1), N0.getOperand(2));
return DAG.getZeroExtendInReg(VSetCC, DL, N0.getValueType());
}
// If the desired elements are smaller or larger than the source
// elements we can use a matching integer vector type and then
// truncate/any extend followed by zext_in_reg.
EVT MatchingVectorType = N00VT.changeVectorElementTypeToInteger();
SDValue VsetCC =
DAG.getNode(ISD::SETCC, DL, MatchingVectorType, N0.getOperand(0),
N0.getOperand(1), N0.getOperand(2));
return DAG.getZeroExtendInReg(DAG.getAnyExtOrTrunc(VsetCC, DL, VT), DL,
N0.getValueType());
}
// zext(setcc x,y,cc) -> zext(select x, y, true, false, cc)
SDLoc DL(N);
EVT N0VT = N0.getValueType();
EVT N00VT = N0.getOperand(0).getValueType();
if (SDValue SCC = SimplifySelectCC(
DL, N0.getOperand(0), N0.getOperand(1),
DAG.getBoolConstant(true, DL, N0VT, N00VT),
DAG.getBoolConstant(false, DL, N0VT, N00VT),
cast<CondCodeSDNode>(N0.getOperand(2))->get(), true))
return DAG.getNode(ISD::ZERO_EXTEND, DL, VT, SCC);
}
// (zext (shl (zext x), cst)) -> (shl (zext x), cst)
if ((N0.getOpcode() == ISD::SHL || N0.getOpcode() == ISD::SRL) &&
isa<ConstantSDNode>(N0.getOperand(1)) &&
N0.getOperand(0).getOpcode() == ISD::ZERO_EXTEND &&
N0.hasOneUse()) {
SDValue ShAmt = N0.getOperand(1);
if (N0.getOpcode() == ISD::SHL) {
SDValue InnerZExt = N0.getOperand(0);
// If the original shl may be shifting out bits, do not perform this
// transformation.
unsigned KnownZeroBits = InnerZExt.getValueSizeInBits() -
InnerZExt.getOperand(0).getValueSizeInBits();
if (cast<ConstantSDNode>(ShAmt)->getAPIntValue().ugt(KnownZeroBits))
return SDValue();
}
SDLoc DL(N);
// Ensure that the shift amount is wide enough for the shifted value.
if (Log2_32_Ceil(VT.getSizeInBits()) > ShAmt.getValueSizeInBits())
ShAmt = DAG.getNode(ISD::ZERO_EXTEND, DL, MVT::i32, ShAmt);
return DAG.getNode(N0.getOpcode(), DL, VT,
DAG.getNode(ISD::ZERO_EXTEND, DL, VT, N0.getOperand(0)),
ShAmt);
}
if (SDValue NewVSel = matchVSelectOpSizesWithSetCC(N))
return NewVSel;
if (SDValue NewCtPop = widenCtPop(N, DAG))
return NewCtPop;
if (SDValue Res = tryToFoldExtendSelectLoad(N, TLI, DAG))
return Res;
return SDValue();
}
SDValue DAGCombiner::visitANY_EXTEND(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// aext(undef) = undef
if (N0.isUndef())
return DAG.getUNDEF(VT);
if (SDValue Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes))
return Res;
// fold (aext (aext x)) -> (aext x)
// fold (aext (zext x)) -> (zext x)
// fold (aext (sext x)) -> (sext x)
if (N0.getOpcode() == ISD::ANY_EXTEND ||
N0.getOpcode() == ISD::ZERO_EXTEND ||
N0.getOpcode() == ISD::SIGN_EXTEND)
return DAG.getNode(N0.getOpcode(), SDLoc(N), VT, N0.getOperand(0));
// fold (aext (truncate (load x))) -> (aext (smaller load x))
// fold (aext (truncate (srl (load x), c))) -> (aext (small load (x+c/n)))
if (N0.getOpcode() == ISD::TRUNCATE) {
if (SDValue NarrowLoad = reduceLoadWidth(N0.getNode())) {
SDNode *oye = N0.getOperand(0).getNode();
if (NarrowLoad.getNode() != N0.getNode()) {
CombineTo(N0.getNode(), NarrowLoad);
// CombineTo deleted the truncate, if needed, but not what's under it.
AddToWorklist(oye);
}
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
}
// fold (aext (truncate x))
if (N0.getOpcode() == ISD::TRUNCATE)
return DAG.getAnyExtOrTrunc(N0.getOperand(0), SDLoc(N), VT);
// Fold (aext (and (trunc x), cst)) -> (and x, cst)
// if the trunc is not free.
if (N0.getOpcode() == ISD::AND &&
N0.getOperand(0).getOpcode() == ISD::TRUNCATE &&
N0.getOperand(1).getOpcode() == ISD::Constant &&
!TLI.isTruncateFree(N0.getOperand(0).getOperand(0).getValueType(),
N0.getValueType())) {
SDLoc DL(N);
SDValue X = DAG.getAnyExtOrTrunc(N0.getOperand(0).getOperand(0), DL, VT);
SDValue Y = DAG.getNode(ISD::ANY_EXTEND, DL, VT, N0.getOperand(1));
assert(isa<ConstantSDNode>(Y) && "Expected constant to be folded!");
return DAG.getNode(ISD::AND, DL, VT, X, Y);
}
// fold (aext (load x)) -> (aext (truncate (extload x)))
// None of the supported targets knows how to perform load and any_ext
// on vectors in one instruction, so attempt to fold to zext instead.
if (VT.isVector()) {
// Try to simplify (zext (load x)).
if (SDValue foldedExt =
tryToFoldExtOfLoad(DAG, *this, TLI, VT, LegalOperations, N, N0,
ISD::ZEXTLOAD, ISD::ZERO_EXTEND))
return foldedExt;
} else if (ISD::isNON_EXTLoad(N0.getNode()) &&
ISD::isUNINDEXEDLoad(N0.getNode()) &&
TLI.isLoadExtLegal(ISD::EXTLOAD, VT, N0.getValueType())) {
bool DoXform = true;
SmallVector<SDNode *, 4> SetCCs;
if (!N0.hasOneUse())
DoXform =
ExtendUsesToFormExtLoad(VT, N, N0, ISD::ANY_EXTEND, SetCCs, TLI);
if (DoXform) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
SDValue ExtLoad = DAG.getExtLoad(ISD::EXTLOAD, SDLoc(N), VT,
LN0->getChain(), LN0->getBasePtr(),
N0.getValueType(), LN0->getMemOperand());
ExtendSetCCUses(SetCCs, N0, ExtLoad, ISD::ANY_EXTEND);
// If the load value is used only by N, replace it via CombineTo N.
bool NoReplaceTrunc = N0.hasOneUse();
CombineTo(N, ExtLoad);
if (NoReplaceTrunc) {
DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
recursivelyDeleteUnusedNodes(LN0);
} else {
SDValue Trunc =
DAG.getNode(ISD::TRUNCATE, SDLoc(N0), N0.getValueType(), ExtLoad);
CombineTo(LN0, Trunc, ExtLoad.getValue(1));
}
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
}
// fold (aext (zextload x)) -> (aext (truncate (zextload x)))
// fold (aext (sextload x)) -> (aext (truncate (sextload x)))
// fold (aext ( extload x)) -> (aext (truncate (extload x)))
if (N0.getOpcode() == ISD::LOAD && !ISD::isNON_EXTLoad(N0.getNode()) &&
ISD::isUNINDEXEDLoad(N0.getNode()) && N0.hasOneUse()) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
ISD::LoadExtType ExtType = LN0->getExtensionType();
EVT MemVT = LN0->getMemoryVT();
if (!LegalOperations || TLI.isLoadExtLegal(ExtType, VT, MemVT)) {
SDValue ExtLoad = DAG.getExtLoad(ExtType, SDLoc(N),
VT, LN0->getChain(), LN0->getBasePtr(),
MemVT, LN0->getMemOperand());
CombineTo(N, ExtLoad);
DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
recursivelyDeleteUnusedNodes(LN0);
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
}
if (N0.getOpcode() == ISD::SETCC) {
// For vectors:
// aext(setcc) -> vsetcc
// aext(setcc) -> truncate(vsetcc)
// aext(setcc) -> aext(vsetcc)
// Only do this before legalize for now.
if (VT.isVector() && !LegalOperations) {
EVT N00VT = N0.getOperand(0).getValueType();
if (getSetCCResultType(N00VT) == N0.getValueType())
return SDValue();
// We know that the # elements of the results is the same as the
// # elements of the compare (and the # elements of the compare result
// for that matter). Check to see that they are the same size. If so,
// we know that the element size of the sext'd result matches the
// element size of the compare operands.
if (VT.getSizeInBits() == N00VT.getSizeInBits())
return DAG.getSetCC(SDLoc(N), VT, N0.getOperand(0),
N0.getOperand(1),
cast<CondCodeSDNode>(N0.getOperand(2))->get());
// If the desired elements are smaller or larger than the source
// elements we can use a matching integer vector type and then
// truncate/any extend
EVT MatchingVectorType = N00VT.changeVectorElementTypeToInteger();
SDValue VsetCC =
DAG.getSetCC(SDLoc(N), MatchingVectorType, N0.getOperand(0),
N0.getOperand(1),
cast<CondCodeSDNode>(N0.getOperand(2))->get());
return DAG.getAnyExtOrTrunc(VsetCC, SDLoc(N), VT);
}
// aext(setcc x,y,cc) -> select_cc x, y, 1, 0, cc
SDLoc DL(N);
if (SDValue SCC = SimplifySelectCC(
DL, N0.getOperand(0), N0.getOperand(1), DAG.getConstant(1, DL, VT),
DAG.getConstant(0, DL, VT),
cast<CondCodeSDNode>(N0.getOperand(2))->get(), true))
return SCC;
}
if (SDValue NewCtPop = widenCtPop(N, DAG))
return NewCtPop;
if (SDValue Res = tryToFoldExtendSelectLoad(N, TLI, DAG))
return Res;
return SDValue();
}
SDValue DAGCombiner::visitAssertExt(SDNode *N) {
unsigned Opcode = N->getOpcode();
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT AssertVT = cast<VTSDNode>(N1)->getVT();
// fold (assert?ext (assert?ext x, vt), vt) -> (assert?ext x, vt)
if (N0.getOpcode() == Opcode &&
AssertVT == cast<VTSDNode>(N0.getOperand(1))->getVT())
return N0;
if (N0.getOpcode() == ISD::TRUNCATE && N0.hasOneUse() &&
N0.getOperand(0).getOpcode() == Opcode) {
// We have an assert, truncate, assert sandwich. Make one stronger assert
// by asserting on the smallest asserted type to the larger source type.
// This eliminates the later assert:
// assert (trunc (assert X, i8) to iN), i1 --> trunc (assert X, i1) to iN
// assert (trunc (assert X, i1) to iN), i8 --> trunc (assert X, i1) to iN
SDLoc DL(N);
SDValue BigA = N0.getOperand(0);
EVT BigA_AssertVT = cast<VTSDNode>(BigA.getOperand(1))->getVT();
EVT MinAssertVT = AssertVT.bitsLT(BigA_AssertVT) ? AssertVT : BigA_AssertVT;
SDValue MinAssertVTVal = DAG.getValueType(MinAssertVT);
SDValue NewAssert = DAG.getNode(Opcode, DL, BigA.getValueType(),
BigA.getOperand(0), MinAssertVTVal);
return DAG.getNode(ISD::TRUNCATE, DL, N->getValueType(0), NewAssert);
}
// If we have (AssertZext (truncate (AssertSext X, iX)), iY) and Y is smaller
// than X. Just move the AssertZext in front of the truncate and drop the
// AssertSExt.
if (N0.getOpcode() == ISD::TRUNCATE && N0.hasOneUse() &&
N0.getOperand(0).getOpcode() == ISD::AssertSext &&
Opcode == ISD::AssertZext) {
SDValue BigA = N0.getOperand(0);
EVT BigA_AssertVT = cast<VTSDNode>(BigA.getOperand(1))->getVT();
if (AssertVT.bitsLT(BigA_AssertVT)) {
SDLoc DL(N);
SDValue NewAssert = DAG.getNode(Opcode, DL, BigA.getValueType(),
BigA.getOperand(0), N1);
return DAG.getNode(ISD::TRUNCATE, DL, N->getValueType(0), NewAssert);
}
}
return SDValue();
}
SDValue DAGCombiner::visitAssertAlign(SDNode *N) {
SDLoc DL(N);
Align AL = cast<AssertAlignSDNode>(N)->getAlign();
SDValue N0 = N->getOperand(0);
// Fold (assertalign (assertalign x, AL0), AL1) ->
// (assertalign x, max(AL0, AL1))
if (auto *AAN = dyn_cast<AssertAlignSDNode>(N0))
return DAG.getAssertAlign(DL, N0.getOperand(0),
std::max(AL, AAN->getAlign()));
// In rare cases, there are trivial arithmetic ops in source operands. Sink
// this assert down to source operands so that those arithmetic ops could be
// exposed to the DAG combining.
switch (N0.getOpcode()) {
default:
break;
case ISD::ADD:
case ISD::SUB: {
unsigned AlignShift = Log2(AL);
SDValue LHS = N0.getOperand(0);
SDValue RHS = N0.getOperand(1);
unsigned LHSAlignShift = DAG.computeKnownBits(LHS).countMinTrailingZeros();
unsigned RHSAlignShift = DAG.computeKnownBits(RHS).countMinTrailingZeros();
if (LHSAlignShift >= AlignShift || RHSAlignShift >= AlignShift) {
if (LHSAlignShift < AlignShift)
LHS = DAG.getAssertAlign(DL, LHS, AL);
if (RHSAlignShift < AlignShift)
RHS = DAG.getAssertAlign(DL, RHS, AL);
return DAG.getNode(N0.getOpcode(), DL, N0.getValueType(), LHS, RHS);
}
break;
}
}
return SDValue();
}
/// If the result of a load is shifted/masked/truncated to an effectively
/// narrower type, try to transform the load to a narrower type and/or
/// use an extending load.
SDValue DAGCombiner::reduceLoadWidth(SDNode *N) {
unsigned Opc = N->getOpcode();
ISD::LoadExtType ExtType = ISD::NON_EXTLOAD;
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
EVT ExtVT = VT;
// This transformation isn't valid for vector loads.
if (VT.isVector())
return SDValue();
// The ShAmt variable is used to indicate that we've consumed a right
// shift. I.e. we want to narrow the width of the load by skipping to load the
// ShAmt least significant bits.
unsigned ShAmt = 0;
// A special case is when the least significant bits from the load are masked
// away, but using an AND rather than a right shift. HasShiftedOffset is used
// to indicate that the narrowed load should be left-shifted ShAmt bits to get
// the result.
bool HasShiftedOffset = false;
// Special case: SIGN_EXTEND_INREG is basically truncating to ExtVT then
// extended to VT.
if (Opc == ISD::SIGN_EXTEND_INREG) {
ExtType = ISD::SEXTLOAD;
ExtVT = cast<VTSDNode>(N->getOperand(1))->getVT();
} else if (Opc == ISD::SRL || Opc == ISD::SRA) {
// Another special-case: SRL/SRA is basically zero/sign-extending a narrower
// value, or it may be shifting a higher subword, half or byte into the
// lowest bits.
// Only handle shift with constant shift amount, and the shiftee must be a
// load.
auto *LN = dyn_cast<LoadSDNode>(N0);
auto *N1C = dyn_cast<ConstantSDNode>(N->getOperand(1));
if (!N1C || !LN)
return SDValue();
// If the shift amount is larger than the memory type then we're not
// accessing any of the loaded bytes.
ShAmt = N1C->getZExtValue();
uint64_t MemoryWidth = LN->getMemoryVT().getScalarSizeInBits();
if (MemoryWidth <= ShAmt)
return SDValue();
// Attempt to fold away the SRL by using ZEXTLOAD and SRA by using SEXTLOAD.
ExtType = Opc == ISD::SRL ? ISD::ZEXTLOAD : ISD::SEXTLOAD;
ExtVT = EVT::getIntegerVT(*DAG.getContext(), MemoryWidth - ShAmt);
// If original load is a SEXTLOAD then we can't simply replace it by a
// ZEXTLOAD (we could potentially replace it by a more narrow SEXTLOAD
// followed by a ZEXT, but that is not handled at the moment). Similarly if
// the original load is a ZEXTLOAD and we want to use a SEXTLOAD.
if ((LN->getExtensionType() == ISD::SEXTLOAD ||
LN->getExtensionType() == ISD::ZEXTLOAD) &&
LN->getExtensionType() != ExtType)
return SDValue();
} else if (Opc == ISD::AND) {
// An AND with a constant mask is the same as a truncate + zero-extend.
auto AndC = dyn_cast<ConstantSDNode>(N->getOperand(1));
if (!AndC)
return SDValue();
const APInt &Mask = AndC->getAPIntValue();
unsigned ActiveBits = 0;
if (Mask.isMask()) {
ActiveBits = Mask.countTrailingOnes();
} else if (Mask.isShiftedMask(ShAmt, ActiveBits)) {
HasShiftedOffset = true;
} else {
return SDValue();
}
ExtType = ISD::ZEXTLOAD;
ExtVT = EVT::getIntegerVT(*DAG.getContext(), ActiveBits);
}
// In case Opc==SRL we've already prepared ExtVT/ExtType/ShAmt based on doing
// a right shift. Here we redo some of those checks, to possibly adjust the
// ExtVT even further based on "a masking AND". We could also end up here for
// other reasons (e.g. based on Opc==TRUNCATE) and that is why some checks
// need to be done here as well.
if (Opc == ISD::SRL || N0.getOpcode() == ISD::SRL) {
SDValue SRL = Opc == ISD::SRL ? SDValue(N, 0) : N0;
// Bail out when the SRL has more than one use. This is done for historical
// (undocumented) reasons. Maybe intent was to guard the AND-masking below
// check below? And maybe it could be non-profitable to do the transform in
// case the SRL has multiple uses and we get here with Opc!=ISD::SRL?
// FIXME: Can't we just skip this check for the Opc==ISD::SRL case.
if (!SRL.hasOneUse())
return SDValue();
// Only handle shift with constant shift amount, and the shiftee must be a
// load.
auto *LN = dyn_cast<LoadSDNode>(SRL.getOperand(0));
auto *SRL1C = dyn_cast<ConstantSDNode>(SRL.getOperand(1));
if (!SRL1C || !LN)
return SDValue();
// If the shift amount is larger than the input type then we're not
// accessing any of the loaded bytes. If the load was a zextload/extload
// then the result of the shift+trunc is zero/undef (handled elsewhere).
ShAmt = SRL1C->getZExtValue();
uint64_t MemoryWidth = LN->getMemoryVT().getSizeInBits();
if (ShAmt >= MemoryWidth)
return SDValue();
// Because a SRL must be assumed to *need* to zero-extend the high bits
// (as opposed to anyext the high bits), we can't combine the zextload
// lowering of SRL and an sextload.
if (LN->getExtensionType() == ISD::SEXTLOAD)
return SDValue();
// Avoid reading outside the memory accessed by the original load (could
// happened if we only adjust the load base pointer by ShAmt). Instead we
// try to narrow the load even further. The typical scenario here is:
// (i64 (truncate (i96 (srl (load x), 64)))) ->
// (i64 (truncate (i96 (zextload (load i32 + offset) from i32))))
if (ExtVT.getScalarSizeInBits() > MemoryWidth - ShAmt) {
// Don't replace sextload by zextload.
if (ExtType == ISD::SEXTLOAD)
return SDValue();
// Narrow the load.
ExtType = ISD::ZEXTLOAD;
ExtVT = EVT::getIntegerVT(*DAG.getContext(), MemoryWidth - ShAmt);
}
// If the SRL is only used by a masking AND, we may be able to adjust
// the ExtVT to make the AND redundant.
SDNode *Mask = *(SRL->use_begin());
if (SRL.hasOneUse() && Mask->getOpcode() == ISD::AND &&
isa<ConstantSDNode>(Mask->getOperand(1))) {
const APInt& ShiftMask = Mask->getConstantOperandAPInt(1);
if (ShiftMask.isMask()) {
EVT MaskedVT = EVT::getIntegerVT(*DAG.getContext(),
ShiftMask.countTrailingOnes());
// If the mask is smaller, recompute the type.
if ((ExtVT.getScalarSizeInBits() > MaskedVT.getScalarSizeInBits()) &&
TLI.isLoadExtLegal(ExtType, SRL.getValueType(), MaskedVT))
ExtVT = MaskedVT;
}
}
N0 = SRL.getOperand(0);
}
// If the load is shifted left (and the result isn't shifted back right), we
// can fold a truncate through the shift. The typical scenario is that N
// points at a TRUNCATE here so the attempted fold is:
// (truncate (shl (load x), c))) -> (shl (narrow load x), c)
// ShLeftAmt will indicate how much a narrowed load should be shifted left.
unsigned ShLeftAmt = 0;
if (ShAmt == 0 && N0.getOpcode() == ISD::SHL && N0.hasOneUse() &&
ExtVT == VT && TLI.isNarrowingProfitable(N0.getValueType(), VT)) {
if (ConstantSDNode *N01 = dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
ShLeftAmt = N01->getZExtValue();
N0 = N0.getOperand(0);
}
}
// If we haven't found a load, we can't narrow it.
if (!isa<LoadSDNode>(N0))
return SDValue();
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
// Reducing the width of a volatile load is illegal. For atomics, we may be
// able to reduce the width provided we never widen again. (see D66309)
if (!LN0->isSimple() ||
!isLegalNarrowLdSt(LN0, ExtType, ExtVT, ShAmt))
return SDValue();
auto AdjustBigEndianShift = [&](unsigned ShAmt) {
unsigned LVTStoreBits =
LN0->getMemoryVT().getStoreSizeInBits().getFixedSize();
unsigned EVTStoreBits = ExtVT.getStoreSizeInBits().getFixedSize();
return LVTStoreBits - EVTStoreBits - ShAmt;
};
// We need to adjust the pointer to the load by ShAmt bits in order to load
// the correct bytes.
unsigned PtrAdjustmentInBits =
DAG.getDataLayout().isBigEndian() ? AdjustBigEndianShift(ShAmt) : ShAmt;
uint64_t PtrOff = PtrAdjustmentInBits / 8;
Align NewAlign = commonAlignment(LN0->getAlign(), PtrOff);
SDLoc DL(LN0);
// The original load itself didn't wrap, so an offset within it doesn't.
SDNodeFlags Flags;
Flags.setNoUnsignedWrap(true);
SDValue NewPtr = DAG.getMemBasePlusOffset(LN0->getBasePtr(),
TypeSize::Fixed(PtrOff), DL, Flags);
AddToWorklist(NewPtr.getNode());
SDValue Load;
if (ExtType == ISD::NON_EXTLOAD)
Load = DAG.getLoad(VT, DL, LN0->getChain(), NewPtr,
LN0->getPointerInfo().getWithOffset(PtrOff), NewAlign,
LN0->getMemOperand()->getFlags(), LN0->getAAInfo());
else
Load = DAG.getExtLoad(ExtType, DL, VT, LN0->getChain(), NewPtr,
LN0->getPointerInfo().getWithOffset(PtrOff), ExtVT,
NewAlign, LN0->getMemOperand()->getFlags(),
LN0->getAAInfo());
// Replace the old load's chain with the new load's chain.
WorklistRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(N0.getValue(1), Load.getValue(1));
// Shift the result left, if we've swallowed a left shift.
SDValue Result = Load;
if (ShLeftAmt != 0) {
EVT ShImmTy = getShiftAmountTy(Result.getValueType());
if (!isUIntN(ShImmTy.getScalarSizeInBits(), ShLeftAmt))
ShImmTy = VT;
// If the shift amount is as large as the result size (but, presumably,
// no larger than the source) then the useful bits of the result are
// zero; we can't simply return the shortened shift, because the result
// of that operation is undefined.
if (ShLeftAmt >= VT.getScalarSizeInBits())
Result = DAG.getConstant(0, DL, VT);
else
Result = DAG.getNode(ISD::SHL, DL, VT,
Result, DAG.getConstant(ShLeftAmt, DL, ShImmTy));
}
if (HasShiftedOffset) {
// We're using a shifted mask, so the load now has an offset. This means
// that data has been loaded into the lower bytes than it would have been
// before, so we need to shl the loaded data into the correct position in the
// register.
SDValue ShiftC = DAG.getConstant(ShAmt, DL, VT);
Result = DAG.getNode(ISD::SHL, DL, VT, Result, ShiftC);
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result);
}
// Return the new loaded value.
return Result;
}
SDValue DAGCombiner::visitSIGN_EXTEND_INREG(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
EVT ExtVT = cast<VTSDNode>(N1)->getVT();
unsigned VTBits = VT.getScalarSizeInBits();
unsigned ExtVTBits = ExtVT.getScalarSizeInBits();
// sext_vector_inreg(undef) = 0 because the top bit will all be the same.
if (N0.isUndef())
return DAG.getConstant(0, SDLoc(N), VT);
// fold (sext_in_reg c1) -> c1
if (DAG.isConstantIntBuildVectorOrConstantInt(N0))
return DAG.getNode(ISD::SIGN_EXTEND_INREG, SDLoc(N), VT, N0, N1);
// If the input is already sign extended, just drop the extension.
if (ExtVTBits >= DAG.ComputeMaxSignificantBits(N0))
return N0;
// fold (sext_in_reg (sext_in_reg x, VT2), VT1) -> (sext_in_reg x, minVT) pt2
if (N0.getOpcode() == ISD::SIGN_EXTEND_INREG &&
ExtVT.bitsLT(cast<VTSDNode>(N0.getOperand(1))->getVT()))
return DAG.getNode(ISD::SIGN_EXTEND_INREG, SDLoc(N), VT, N0.getOperand(0),
N1);
// fold (sext_in_reg (sext x)) -> (sext x)
// fold (sext_in_reg (aext x)) -> (sext x)
// if x is small enough or if we know that x has more than 1 sign bit and the
// sign_extend_inreg is extending from one of them.
if (N0.getOpcode() == ISD::SIGN_EXTEND || N0.getOpcode() == ISD::ANY_EXTEND) {
SDValue N00 = N0.getOperand(0);
unsigned N00Bits = N00.getScalarValueSizeInBits();
if ((N00Bits <= ExtVTBits ||
DAG.ComputeMaxSignificantBits(N00) <= ExtVTBits) &&
(!LegalOperations || TLI.isOperationLegal(ISD::SIGN_EXTEND, VT)))
return DAG.getNode(ISD::SIGN_EXTEND, SDLoc(N), VT, N00);
}
// fold (sext_in_reg (*_extend_vector_inreg x)) -> (sext_vector_inreg x)
// if x is small enough or if we know that x has more than 1 sign bit and the
// sign_extend_inreg is extending from one of them.
if (N0.getOpcode() == ISD::ANY_EXTEND_VECTOR_INREG ||
N0.getOpcode() == ISD::SIGN_EXTEND_VECTOR_INREG ||
N0.getOpcode() == ISD::ZERO_EXTEND_VECTOR_INREG) {
SDValue N00 = N0.getOperand(0);
unsigned N00Bits = N00.getScalarValueSizeInBits();
unsigned DstElts = N0.getValueType().getVectorMinNumElements();
unsigned SrcElts = N00.getValueType().getVectorMinNumElements();
bool IsZext = N0.getOpcode() == ISD::ZERO_EXTEND_VECTOR_INREG;
APInt DemandedSrcElts = APInt::getLowBitsSet(SrcElts, DstElts);
if ((N00Bits == ExtVTBits ||
(!IsZext && (N00Bits < ExtVTBits ||
DAG.ComputeMaxSignificantBits(N00) <= ExtVTBits))) &&
(!LegalOperations ||
TLI.isOperationLegal(ISD::SIGN_EXTEND_VECTOR_INREG, VT)))
return DAG.getNode(ISD::SIGN_EXTEND_VECTOR_INREG, SDLoc(N), VT, N00);
}
// fold (sext_in_reg (zext x)) -> (sext x)
// iff we are extending the source sign bit.
if (N0.getOpcode() == ISD::ZERO_EXTEND) {
SDValue N00 = N0.getOperand(0);
if (N00.getScalarValueSizeInBits() == ExtVTBits &&
(!LegalOperations || TLI.isOperationLegal(ISD::SIGN_EXTEND, VT)))
return DAG.getNode(ISD::SIGN_EXTEND, SDLoc(N), VT, N00, N1);
}
// fold (sext_in_reg x) -> (zext_in_reg x) if the sign bit is known zero.
if (DAG.MaskedValueIsZero(N0, APInt::getOneBitSet(VTBits, ExtVTBits - 1)))
return DAG.getZeroExtendInReg(N0, SDLoc(N), ExtVT);
// fold operands of sext_in_reg based on knowledge that the top bits are not
// demanded.
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
// fold (sext_in_reg (load x)) -> (smaller sextload x)
// fold (sext_in_reg (srl (load x), c)) -> (smaller sextload (x+c/evtbits))
if (SDValue NarrowLoad = reduceLoadWidth(N))
return NarrowLoad;
// fold (sext_in_reg (srl X, 24), i8) -> (sra X, 24)
// fold (sext_in_reg (srl X, 23), i8) -> (sra X, 23) iff possible.
// We already fold "(sext_in_reg (srl X, 25), i8) -> srl X, 25" above.
if (N0.getOpcode() == ISD::SRL) {
if (auto *ShAmt = dyn_cast<ConstantSDNode>(N0.getOperand(1)))
if (ShAmt->getAPIntValue().ule(VTBits - ExtVTBits)) {
// We can turn this into an SRA iff the input to the SRL is already sign
// extended enough.
unsigned InSignBits = DAG.ComputeNumSignBits(N0.getOperand(0));
if (((VTBits - ExtVTBits) - ShAmt->getZExtValue()) < InSignBits)
return DAG.getNode(ISD::SRA, SDLoc(N), VT, N0.getOperand(0),
N0.getOperand(1));
}
}
// fold (sext_inreg (extload x)) -> (sextload x)
// If sextload is not supported by target, we can only do the combine when
// load has one use. Doing otherwise can block folding the extload with other
// extends that the target does support.
if (ISD::isEXTLoad(N0.getNode()) &&
ISD::isUNINDEXEDLoad(N0.getNode()) &&
ExtVT == cast<LoadSDNode>(N0)->getMemoryVT() &&
((!LegalOperations && cast<LoadSDNode>(N0)->isSimple() &&
N0.hasOneUse()) ||
TLI.isLoadExtLegal(ISD::SEXTLOAD, VT, ExtVT))) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
SDValue ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, SDLoc(N), VT,
LN0->getChain(),
LN0->getBasePtr(), ExtVT,
LN0->getMemOperand());
CombineTo(N, ExtLoad);
CombineTo(N0.getNode(), ExtLoad, ExtLoad.getValue(1));
AddToWorklist(ExtLoad.getNode());
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
// fold (sext_inreg (zextload x)) -> (sextload x) iff load has one use
if (ISD::isZEXTLoad(N0.getNode()) && ISD::isUNINDEXEDLoad(N0.getNode()) &&
N0.hasOneUse() &&
ExtVT == cast<LoadSDNode>(N0)->getMemoryVT() &&
((!LegalOperations && cast<LoadSDNode>(N0)->isSimple()) &&
TLI.isLoadExtLegal(ISD::SEXTLOAD, VT, ExtVT))) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
SDValue ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, SDLoc(N), VT,
LN0->getChain(),
LN0->getBasePtr(), ExtVT,
LN0->getMemOperand());
CombineTo(N, ExtLoad);
CombineTo(N0.getNode(), ExtLoad, ExtLoad.getValue(1));
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
// fold (sext_inreg (masked_load x)) -> (sext_masked_load x)
// ignore it if the masked load is already sign extended
if (MaskedLoadSDNode *Ld = dyn_cast<MaskedLoadSDNode>(N0)) {
if (ExtVT == Ld->getMemoryVT() && N0.hasOneUse() &&
Ld->getExtensionType() != ISD::LoadExtType::NON_EXTLOAD &&
TLI.isLoadExtLegal(ISD::SEXTLOAD, VT, ExtVT)) {
SDValue ExtMaskedLoad = DAG.getMaskedLoad(
VT, SDLoc(N), Ld->getChain(), Ld->getBasePtr(), Ld->getOffset(),
Ld->getMask(), Ld->getPassThru(), ExtVT, Ld->getMemOperand(),
Ld->getAddressingMode(), ISD::SEXTLOAD, Ld->isExpandingLoad());
CombineTo(N, ExtMaskedLoad);
CombineTo(N0.getNode(), ExtMaskedLoad, ExtMaskedLoad.getValue(1));
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
}
// fold (sext_inreg (masked_gather x)) -> (sext_masked_gather x)
if (auto *GN0 = dyn_cast<MaskedGatherSDNode>(N0)) {
if (SDValue(GN0, 0).hasOneUse() &&
ExtVT == GN0->getMemoryVT() &&
TLI.isVectorLoadExtDesirable(SDValue(SDValue(GN0, 0)))) {
SDValue Ops[] = {GN0->getChain(), GN0->getPassThru(), GN0->getMask(),
GN0->getBasePtr(), GN0->getIndex(), GN0->getScale()};
SDValue ExtLoad = DAG.getMaskedGather(
DAG.getVTList(VT, MVT::Other), ExtVT, SDLoc(N), Ops,
GN0->getMemOperand(), GN0->getIndexType(), ISD::SEXTLOAD);
CombineTo(N, ExtLoad);
CombineTo(N0.getNode(), ExtLoad, ExtLoad.getValue(1));
AddToWorklist(ExtLoad.getNode());
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
}
// Form (sext_inreg (bswap >> 16)) or (sext_inreg (rotl (bswap) 16))
if (ExtVTBits <= 16 && N0.getOpcode() == ISD::OR) {
if (SDValue BSwap = MatchBSwapHWordLow(N0.getNode(), N0.getOperand(0),
N0.getOperand(1), false))
return DAG.getNode(ISD::SIGN_EXTEND_INREG, SDLoc(N), VT, BSwap, N1);
}
return SDValue();
}
SDValue DAGCombiner::visitEXTEND_VECTOR_INREG(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// {s/z}ext_vector_inreg(undef) = 0 because the top bits must be the same.
if (N0.isUndef())
return DAG.getConstant(0, SDLoc(N), VT);
if (SDValue Res = tryToFoldExtendOfConstant(N, TLI, DAG, LegalTypes))
return Res;
if (SimplifyDemandedVectorElts(SDValue(N, 0)))
return SDValue(N, 0);
return SDValue();
}
SDValue DAGCombiner::visitTRUNCATE(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
EVT SrcVT = N0.getValueType();
bool isLE = DAG.getDataLayout().isLittleEndian();
// noop truncate
if (SrcVT == VT)
return N0;
// fold (truncate (truncate x)) -> (truncate x)
if (N0.getOpcode() == ISD::TRUNCATE)
return DAG.getNode(ISD::TRUNCATE, SDLoc(N), VT, N0.getOperand(0));
// fold (truncate c1) -> c1
if (DAG.isConstantIntBuildVectorOrConstantInt(N0)) {
SDValue C = DAG.getNode(ISD::TRUNCATE, SDLoc(N), VT, N0);
if (C.getNode() != N)
return C;
}
// fold (truncate (ext x)) -> (ext x) or (truncate x) or x
if (N0.getOpcode() == ISD::ZERO_EXTEND ||
N0.getOpcode() == ISD::SIGN_EXTEND ||
N0.getOpcode() == ISD::ANY_EXTEND) {
// if the source is smaller than the dest, we still need an extend.
if (N0.getOperand(0).getValueType().bitsLT(VT))
return DAG.getNode(N0.getOpcode(), SDLoc(N), VT, N0.getOperand(0));
// if the source is larger than the dest, than we just need the truncate.
if (N0.getOperand(0).getValueType().bitsGT(VT))
return DAG.getNode(ISD::TRUNCATE, SDLoc(N), VT, N0.getOperand(0));
// if the source and dest are the same type, we can drop both the extend
// and the truncate.
return N0.getOperand(0);
}
// If this is anyext(trunc), don't fold it, allow ourselves to be folded.
if (N->hasOneUse() && (N->use_begin()->getOpcode() == ISD::ANY_EXTEND))
return SDValue();
// Fold extract-and-trunc into a narrow extract. For example:
// i64 x = EXTRACT_VECTOR_ELT(v2i64 val, i32 1)
// i32 y = TRUNCATE(i64 x)
// -- becomes --
// v16i8 b = BITCAST (v2i64 val)
// i8 x = EXTRACT_VECTOR_ELT(v16i8 b, i32 8)
//
// Note: We only run this optimization after type legalization (which often
// creates this pattern) and before operation legalization after which
// we need to be more careful about the vector instructions that we generate.
if (N0.getOpcode() == ISD::EXTRACT_VECTOR_ELT &&
LegalTypes && !LegalOperations && N0->hasOneUse() && VT != MVT::i1) {
EVT VecTy = N0.getOperand(0).getValueType();
EVT ExTy = N0.getValueType();
EVT TrTy = N->getValueType(0);
auto EltCnt = VecTy.getVectorElementCount();
unsigned SizeRatio = ExTy.getSizeInBits()/TrTy.getSizeInBits();
auto NewEltCnt = EltCnt * SizeRatio;
EVT NVT = EVT::getVectorVT(*DAG.getContext(), TrTy, NewEltCnt);
assert(NVT.getSizeInBits() == VecTy.getSizeInBits() && "Invalid Size");
SDValue EltNo = N0->getOperand(1);
if (isa<ConstantSDNode>(EltNo) && isTypeLegal(NVT)) {
int Elt = cast<ConstantSDNode>(EltNo)->getZExtValue();
int Index = isLE ? (Elt*SizeRatio) : (Elt*SizeRatio + (SizeRatio-1));
SDLoc DL(N);
return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, TrTy,
DAG.getBitcast(NVT, N0.getOperand(0)),
DAG.getVectorIdxConstant(Index, DL));
}
}
// trunc (select c, a, b) -> select c, (trunc a), (trunc b)
if (N0.getOpcode() == ISD::SELECT && N0.hasOneUse()) {
if ((!LegalOperations || TLI.isOperationLegal(ISD::SELECT, SrcVT)) &&
TLI.isTruncateFree(SrcVT, VT)) {
SDLoc SL(N0);
SDValue Cond = N0.getOperand(0);
SDValue TruncOp0 = DAG.getNode(ISD::TRUNCATE, SL, VT, N0.getOperand(1));
SDValue TruncOp1 = DAG.getNode(ISD::TRUNCATE, SL, VT, N0.getOperand(2));
return DAG.getNode(ISD::SELECT, SDLoc(N), VT, Cond, TruncOp0, TruncOp1);
}
}
// trunc (shl x, K) -> shl (trunc x), K => K < VT.getScalarSizeInBits()
if (N0.getOpcode() == ISD::SHL && N0.hasOneUse() &&
(!LegalOperations || TLI.isOperationLegal(ISD::SHL, VT)) &&
TLI.isTypeDesirableForOp(ISD::SHL, VT)) {
SDValue Amt = N0.getOperand(1);
KnownBits Known = DAG.computeKnownBits(Amt);
unsigned Size = VT.getScalarSizeInBits();
if (Known.countMaxActiveBits() <= Log2_32(Size)) {
SDLoc SL(N);
EVT AmtVT = TLI.getShiftAmountTy(VT, DAG.getDataLayout());
SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SL, VT, N0.getOperand(0));
if (AmtVT != Amt.getValueType()) {
Amt = DAG.getZExtOrTrunc(Amt, SL, AmtVT);
AddToWorklist(Amt.getNode());
}
return DAG.getNode(ISD::SHL, SL, VT, Trunc, Amt);
}
}
if (SDValue V = foldSubToUSubSat(VT, N0.getNode()))
return V;
// Attempt to pre-truncate BUILD_VECTOR sources.
if (N0.getOpcode() == ISD::BUILD_VECTOR && !LegalOperations &&
TLI.isTruncateFree(SrcVT.getScalarType(), VT.getScalarType()) &&
// Avoid creating illegal types if running after type legalizer.
(!LegalTypes || TLI.isTypeLegal(VT.getScalarType()))) {
SDLoc DL(N);
EVT SVT = VT.getScalarType();
SmallVector<SDValue, 8> TruncOps;
for (const SDValue &Op : N0->op_values()) {
SDValue TruncOp = DAG.getNode(ISD::TRUNCATE, DL, SVT, Op);
TruncOps.push_back(TruncOp);
}
return DAG.getBuildVector(VT, DL, TruncOps);
}
// Fold a series of buildvector, bitcast, and truncate if possible.
// For example fold
// (2xi32 trunc (bitcast ((4xi32)buildvector x, x, y, y) 2xi64)) to
// (2xi32 (buildvector x, y)).
if (Level == AfterLegalizeVectorOps && VT.isVector() &&
N0.getOpcode() == ISD::BITCAST && N0.hasOneUse() &&
N0.getOperand(0).getOpcode() == ISD::BUILD_VECTOR &&
N0.getOperand(0).hasOneUse()) {
SDValue BuildVect = N0.getOperand(0);
EVT BuildVectEltTy = BuildVect.getValueType().getVectorElementType();
EVT TruncVecEltTy = VT.getVectorElementType();
// Check that the element types match.
if (BuildVectEltTy == TruncVecEltTy) {
// Now we only need to compute the offset of the truncated elements.
unsigned BuildVecNumElts = BuildVect.getNumOperands();
unsigned TruncVecNumElts = VT.getVectorNumElements();
unsigned TruncEltOffset = BuildVecNumElts / TruncVecNumElts;
assert((BuildVecNumElts % TruncVecNumElts) == 0 &&
"Invalid number of elements");
SmallVector<SDValue, 8> Opnds;
for (unsigned i = 0, e = BuildVecNumElts; i != e; i += TruncEltOffset)
Opnds.push_back(BuildVect.getOperand(i));
return DAG.getBuildVector(VT, SDLoc(N), Opnds);
}
}
// See if we can simplify the input to this truncate through knowledge that
// only the low bits are being used.
// For example "trunc (or (shl x, 8), y)" // -> trunc y
// Currently we only perform this optimization on scalars because vectors
// may have different active low bits.
if (!VT.isVector()) {
APInt Mask =
APInt::getLowBitsSet(N0.getValueSizeInBits(), VT.getSizeInBits());
if (SDValue Shorter = DAG.GetDemandedBits(N0, Mask))
return DAG.getNode(ISD::TRUNCATE, SDLoc(N), VT, Shorter);
}
// fold (truncate (load x)) -> (smaller load x)
// fold (truncate (srl (load x), c)) -> (smaller load (x+c/evtbits))
if (!LegalTypes || TLI.isTypeDesirableForOp(N0.getOpcode(), VT)) {
if (SDValue Reduced = reduceLoadWidth(N))
return Reduced;
// Handle the case where the load remains an extending load even
// after truncation.
if (N0.hasOneUse() && ISD::isUNINDEXEDLoad(N0.getNode())) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
if (LN0->isSimple() && LN0->getMemoryVT().bitsLT(VT)) {
SDValue NewLoad = DAG.getExtLoad(LN0->getExtensionType(), SDLoc(LN0),
VT, LN0->getChain(), LN0->getBasePtr(),
LN0->getMemoryVT(),
LN0->getMemOperand());
DAG.ReplaceAllUsesOfValueWith(N0.getValue(1), NewLoad.getValue(1));
return NewLoad;
}
}
}
// fold (trunc (concat ... x ...)) -> (concat ..., (trunc x), ...)),
// where ... are all 'undef'.
if (N0.getOpcode() == ISD::CONCAT_VECTORS && !LegalTypes) {
SmallVector<EVT, 8> VTs;
SDValue V;
unsigned Idx = 0;
unsigned NumDefs = 0;
for (unsigned i = 0, e = N0.getNumOperands(); i != e; ++i) {
SDValue X = N0.getOperand(i);
if (!X.isUndef()) {
V = X;
Idx = i;
NumDefs++;
}
// Stop if more than one members are non-undef.
if (NumDefs > 1)
break;
VTs.push_back(EVT::getVectorVT(*DAG.getContext(),
VT.getVectorElementType(),
X.getValueType().getVectorElementCount()));
}
if (NumDefs == 0)
return DAG.getUNDEF(VT);
if (NumDefs == 1) {
assert(V.getNode() && "The single defined operand is empty!");
SmallVector<SDValue, 8> Opnds;
for (unsigned i = 0, e = VTs.size(); i != e; ++i) {
if (i != Idx) {
Opnds.push_back(DAG.getUNDEF(VTs[i]));
continue;
}
SDValue NV = DAG.getNode(ISD::TRUNCATE, SDLoc(V), VTs[i], V);
AddToWorklist(NV.getNode());
Opnds.push_back(NV);
}
return DAG.getNode(ISD::CONCAT_VECTORS, SDLoc(N), VT, Opnds);
}
}
// Fold truncate of a bitcast of a vector to an extract of the low vector
// element.
//
// e.g. trunc (i64 (bitcast v2i32:x)) -> extract_vector_elt v2i32:x, idx
if (N0.getOpcode() == ISD::BITCAST && !VT.isVector()) {
SDValue VecSrc = N0.getOperand(0);
EVT VecSrcVT = VecSrc.getValueType();
if (VecSrcVT.isVector() && VecSrcVT.getScalarType() == VT &&
(!LegalOperations ||
TLI.isOperationLegal(ISD::EXTRACT_VECTOR_ELT, VecSrcVT))) {
SDLoc SL(N);
unsigned Idx = isLE ? 0 : VecSrcVT.getVectorNumElements() - 1;
return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, SL, VT, VecSrc,
DAG.getVectorIdxConstant(Idx, SL));
}
}
// Simplify the operands using demanded-bits information.
if (SimplifyDemandedBits(SDValue(N, 0)))
return SDValue(N, 0);
// (trunc adde(X, Y, Carry)) -> (adde trunc(X), trunc(Y), Carry)
// (trunc addcarry(X, Y, Carry)) -> (addcarry trunc(X), trunc(Y), Carry)
// When the adde's carry is not used.
if ((N0.getOpcode() == ISD::ADDE || N0.getOpcode() == ISD::ADDCARRY) &&
N0.hasOneUse() && !N0->hasAnyUseOfValue(1) &&
// We only do for addcarry before legalize operation
((!LegalOperations && N0.getOpcode() == ISD::ADDCARRY) ||
TLI.isOperationLegal(N0.getOpcode(), VT))) {
SDLoc SL(N);
auto X = DAG.getNode(ISD::TRUNCATE, SL, VT, N0.getOperand(0));
auto Y = DAG.getNode(ISD::TRUNCATE, SL, VT, N0.getOperand(1));
auto VTs = DAG.getVTList(VT, N0->getValueType(1));
return DAG.getNode(N0.getOpcode(), SL, VTs, X, Y, N0.getOperand(2));
}
// fold (truncate (extract_subvector(ext x))) ->
// (extract_subvector x)
// TODO: This can be generalized to cover cases where the truncate and extract
// do not fully cancel each other out.
if (!LegalTypes && N0.getOpcode() == ISD::EXTRACT_SUBVECTOR) {
SDValue N00 = N0.getOperand(0);
if (N00.getOpcode() == ISD::SIGN_EXTEND ||
N00.getOpcode() == ISD::ZERO_EXTEND ||
N00.getOpcode() == ISD::ANY_EXTEND) {
if (N00.getOperand(0)->getValueType(0).getVectorElementType() ==
VT.getVectorElementType())
return DAG.getNode(ISD::EXTRACT_SUBVECTOR, SDLoc(N0->getOperand(0)), VT,
N00.getOperand(0), N0.getOperand(1));
}
}
if (SDValue NewVSel = matchVSelectOpSizesWithSetCC(N))
return NewVSel;
// Narrow a suitable binary operation with a non-opaque constant operand by
// moving it ahead of the truncate. This is limited to pre-legalization
// because targets may prefer a wider type during later combines and invert
// this transform.
switch (N0.getOpcode()) {
case ISD::ADD:
case ISD::SUB:
case ISD::MUL:
case ISD::AND:
case ISD::OR:
case ISD::XOR:
if (!LegalOperations && N0.hasOneUse() &&
(isConstantOrConstantVector(N0.getOperand(0), true) ||
isConstantOrConstantVector(N0.getOperand(1), true))) {
// TODO: We already restricted this to pre-legalization, but for vectors
// we are extra cautious to not create an unsupported operation.
// Target-specific changes are likely needed to avoid regressions here.
if (VT.isScalarInteger() || TLI.isOperationLegal(N0.getOpcode(), VT)) {
SDLoc DL(N);
SDValue NarrowL = DAG.getNode(ISD::TRUNCATE, DL, VT, N0.getOperand(0));
SDValue NarrowR = DAG.getNode(ISD::TRUNCATE, DL, VT, N0.getOperand(1));
return DAG.getNode(N0.getOpcode(), DL, VT, NarrowL, NarrowR);
}
}
break;
case ISD::USUBSAT:
// Truncate the USUBSAT only if LHS is a known zero-extension, its not
// enough to know that the upper bits are zero we must ensure that we don't
// introduce an extra truncate.
if (!LegalOperations && N0.hasOneUse() &&
N0.getOperand(0).getOpcode() == ISD::ZERO_EXTEND &&
N0.getOperand(0).getOperand(0).getScalarValueSizeInBits() <=
VT.getScalarSizeInBits() &&
hasOperation(N0.getOpcode(), VT)) {
return getTruncatedUSUBSAT(VT, SrcVT, N0.getOperand(0), N0.getOperand(1),
DAG, SDLoc(N));
}
break;
}
return SDValue();
}
static SDNode *getBuildPairElt(SDNode *N, unsigned i) {
SDValue Elt = N->getOperand(i);
if (Elt.getOpcode() != ISD::MERGE_VALUES)
return Elt.getNode();
return Elt.getOperand(Elt.getResNo()).getNode();
}
/// build_pair (load, load) -> load
/// if load locations are consecutive.
SDValue DAGCombiner::CombineConsecutiveLoads(SDNode *N, EVT VT) {
assert(N->getOpcode() == ISD::BUILD_PAIR);
auto *LD1 = dyn_cast<LoadSDNode>(getBuildPairElt(N, 0));
auto *LD2 = dyn_cast<LoadSDNode>(getBuildPairElt(N, 1));
// A BUILD_PAIR is always having the least significant part in elt 0 and the
// most significant part in elt 1. So when combining into one large load, we
// need to consider the endianness.
if (DAG.getDataLayout().isBigEndian())
std::swap(LD1, LD2);
if (!LD1 || !LD2 || !ISD::isNON_EXTLoad(LD1) || !ISD::isNON_EXTLoad(LD2) ||
!LD1->hasOneUse() || !LD2->hasOneUse() ||
LD1->getAddressSpace() != LD2->getAddressSpace())
return SDValue();
bool LD1Fast = false;
EVT LD1VT = LD1->getValueType(0);
unsigned LD1Bytes = LD1VT.getStoreSize();
if ((!LegalOperations || TLI.isOperationLegal(ISD::LOAD, VT)) &&
DAG.areNonVolatileConsecutiveLoads(LD2, LD1, LD1Bytes, 1) &&
TLI.allowsMemoryAccess(*DAG.getContext(), DAG.getDataLayout(), VT,
*LD1->getMemOperand(), &LD1Fast) && LD1Fast)
return DAG.getLoad(VT, SDLoc(N), LD1->getChain(), LD1->getBasePtr(),
LD1->getPointerInfo(), LD1->getAlign());
return SDValue();
}
static unsigned getPPCf128HiElementSelector(const SelectionDAG &DAG) {
// On little-endian machines, bitcasting from ppcf128 to i128 does swap the Hi
// and Lo parts; on big-endian machines it doesn't.
return DAG.getDataLayout().isBigEndian() ? 1 : 0;
}
static SDValue foldBitcastedFPLogic(SDNode *N, SelectionDAG &DAG,
const TargetLowering &TLI) {
// If this is not a bitcast to an FP type or if the target doesn't have
// IEEE754-compliant FP logic, we're done.
EVT VT = N->getValueType(0);
if (!VT.isFloatingPoint() || !TLI.hasBitPreservingFPLogic(VT))
return SDValue();
// TODO: Handle cases where the integer constant is a different scalar
// bitwidth to the FP.
SDValue N0 = N->getOperand(0);
EVT SourceVT = N0.getValueType();
if (VT.getScalarSizeInBits() != SourceVT.getScalarSizeInBits())
return SDValue();
unsigned FPOpcode;
APInt SignMask;
switch (N0.getOpcode()) {
case ISD::AND:
FPOpcode = ISD::FABS;
SignMask = ~APInt::getSignMask(SourceVT.getScalarSizeInBits());
break;
case ISD::XOR:
FPOpcode = ISD::FNEG;
SignMask = APInt::getSignMask(SourceVT.getScalarSizeInBits());
break;
case ISD::OR:
FPOpcode = ISD::FABS;
SignMask = APInt::getSignMask(SourceVT.getScalarSizeInBits());
break;
default:
return SDValue();
}
// Fold (bitcast int (and (bitcast fp X to int), 0x7fff...) to fp) -> fabs X
// Fold (bitcast int (xor (bitcast fp X to int), 0x8000...) to fp) -> fneg X
// Fold (bitcast int (or (bitcast fp X to int), 0x8000...) to fp) ->
// fneg (fabs X)
SDValue LogicOp0 = N0.getOperand(0);
ConstantSDNode *LogicOp1 = isConstOrConstSplat(N0.getOperand(1), true);
if (LogicOp1 && LogicOp1->getAPIntValue() == SignMask &&
LogicOp0.getOpcode() == ISD::BITCAST &&
LogicOp0.getOperand(0).getValueType() == VT) {
SDValue FPOp = DAG.getNode(FPOpcode, SDLoc(N), VT, LogicOp0.getOperand(0));
NumFPLogicOpsConv++;
if (N0.getOpcode() == ISD::OR)
return DAG.getNode(ISD::FNEG, SDLoc(N), VT, FPOp);
return FPOp;
}
return SDValue();
}
SDValue DAGCombiner::visitBITCAST(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
if (N0.isUndef())
return DAG.getUNDEF(VT);
// If the input is a BUILD_VECTOR with all constant elements, fold this now.
// Only do this before legalize types, unless both types are integer and the
// scalar type is legal. Only do this before legalize ops, since the target
// maybe depending on the bitcast.
// First check to see if this is all constant.
// TODO: Support FP bitcasts after legalize types.
if (VT.isVector() &&
(!LegalTypes ||
(!LegalOperations && VT.isInteger() && N0.getValueType().isInteger() &&
TLI.isTypeLegal(VT.getVectorElementType()))) &&
N0.getOpcode() == ISD::BUILD_VECTOR && N0->hasOneUse() &&
cast<BuildVectorSDNode>(N0)->isConstant())
return ConstantFoldBITCASTofBUILD_VECTOR(N0.getNode(),
VT.getVectorElementType());
// If the input is a constant, let getNode fold it.
if (isIntOrFPConstant(N0)) {
// If we can't allow illegal operations, we need to check that this is just
// a fp -> int or int -> conversion and that the resulting operation will
// be legal.
if (!LegalOperations ||
(isa<ConstantSDNode>(N0) && VT.isFloatingPoint() && !VT.isVector() &&
TLI.isOperationLegal(ISD::ConstantFP, VT)) ||
(isa<ConstantFPSDNode>(N0) && VT.isInteger() && !VT.isVector() &&
TLI.isOperationLegal(ISD::Constant, VT))) {
SDValue C = DAG.getBitcast(VT, N0);
if (C.getNode() != N)
return C;
}
}
// (conv (conv x, t1), t2) -> (conv x, t2)
if (N0.getOpcode() == ISD::BITCAST)
return DAG.getBitcast(VT, N0.getOperand(0));
// fold (conv (load x)) -> (load (conv*)x)
// If the resultant load doesn't need a higher alignment than the original!
if (ISD::isNormalLoad(N0.getNode()) && N0.hasOneUse() &&
// Do not remove the cast if the types differ in endian layout.
TLI.hasBigEndianPartOrdering(N0.getValueType(), DAG.getDataLayout()) ==
TLI.hasBigEndianPartOrdering(VT, DAG.getDataLayout()) &&
// If the load is volatile, we only want to change the load type if the
// resulting load is legal. Otherwise we might increase the number of
// memory accesses. We don't care if the original type was legal or not
// as we assume software couldn't rely on the number of accesses of an
// illegal type.
((!LegalOperations && cast<LoadSDNode>(N0)->isSimple()) ||
TLI.isOperationLegal(ISD::LOAD, VT))) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
if (TLI.isLoadBitCastBeneficial(N0.getValueType(), VT, DAG,
*LN0->getMemOperand())) {
SDValue Load =
DAG.getLoad(VT, SDLoc(N), LN0->getChain(), LN0->getBasePtr(),
LN0->getPointerInfo(), LN0->getAlign(),
LN0->getMemOperand()->getFlags(), LN0->getAAInfo());
DAG.ReplaceAllUsesOfValueWith(N0.getValue(1), Load.getValue(1));
return Load;
}
}
if (SDValue V = foldBitcastedFPLogic(N, DAG, TLI))
return V;
// fold (bitconvert (fneg x)) -> (xor (bitconvert x), signbit)
// fold (bitconvert (fabs x)) -> (and (bitconvert x), (not signbit))
//
// For ppc_fp128:
// fold (bitcast (fneg x)) ->
// flipbit = signbit
// (xor (bitcast x) (build_pair flipbit, flipbit))
//
// fold (bitcast (fabs x)) ->
// flipbit = (and (extract_element (bitcast x), 0), signbit)
// (xor (bitcast x) (build_pair flipbit, flipbit))
// This often reduces constant pool loads.
if (((N0.getOpcode() == ISD::FNEG && !TLI.isFNegFree(N0.getValueType())) ||
(N0.getOpcode() == ISD::FABS && !TLI.isFAbsFree(N0.getValueType()))) &&
N0->hasOneUse() && VT.isInteger() && !VT.isVector() &&
!N0.getValueType().isVector()) {
SDValue NewConv = DAG.getBitcast(VT, N0.getOperand(0));
AddToWorklist(NewConv.getNode());
SDLoc DL(N);
if (N0.getValueType() == MVT::ppcf128 && !LegalTypes) {
assert(VT.getSizeInBits() == 128);
SDValue SignBit = DAG.getConstant(
APInt::getSignMask(VT.getSizeInBits() / 2), SDLoc(N0), MVT::i64);
SDValue FlipBit;
if (N0.getOpcode() == ISD::FNEG) {
FlipBit = SignBit;
AddToWorklist(FlipBit.getNode());
} else {
assert(N0.getOpcode() == ISD::FABS);
SDValue Hi =
DAG.getNode(ISD::EXTRACT_ELEMENT, SDLoc(NewConv), MVT::i64, NewConv,
DAG.getIntPtrConstant(getPPCf128HiElementSelector(DAG),
SDLoc(NewConv)));
AddToWorklist(Hi.getNode());
FlipBit = DAG.getNode(ISD::AND, SDLoc(N0), MVT::i64, Hi, SignBit);
AddToWorklist(FlipBit.getNode());
}
SDValue FlipBits =
DAG.getNode(ISD::BUILD_PAIR, SDLoc(N0), VT, FlipBit, FlipBit);
AddToWorklist(FlipBits.getNode());
return DAG.getNode(ISD::XOR, DL, VT, NewConv, FlipBits);
}
APInt SignBit = APInt::getSignMask(VT.getSizeInBits());
if (N0.getOpcode() == ISD::FNEG)
return DAG.getNode(ISD::XOR, DL, VT,
NewConv, DAG.getConstant(SignBit, DL, VT));
assert(N0.getOpcode() == ISD::FABS);
return DAG.getNode(ISD::AND, DL, VT,
NewConv, DAG.getConstant(~SignBit, DL, VT));
}
// fold (bitconvert (fcopysign cst, x)) ->
// (or (and (bitconvert x), sign), (and cst, (not sign)))
// Note that we don't handle (copysign x, cst) because this can always be
// folded to an fneg or fabs.
//
// For ppc_fp128:
// fold (bitcast (fcopysign cst, x)) ->
// flipbit = (and (extract_element
// (xor (bitcast cst), (bitcast x)), 0),
// signbit)
// (xor (bitcast cst) (build_pair flipbit, flipbit))
if (N0.getOpcode() == ISD::FCOPYSIGN && N0->hasOneUse() &&
isa<ConstantFPSDNode>(N0.getOperand(0)) && VT.isInteger() &&
!VT.isVector()) {
unsigned OrigXWidth = N0.getOperand(1).getValueSizeInBits();
EVT IntXVT = EVT::getIntegerVT(*DAG.getContext(), OrigXWidth);
if (isTypeLegal(IntXVT)) {
SDValue X = DAG.getBitcast(IntXVT, N0.getOperand(1));
AddToWorklist(X.getNode());
// If X has a different width than the result/lhs, sext it or truncate it.
unsigned VTWidth = VT.getSizeInBits();
if (OrigXWidth < VTWidth) {
X = DAG.getNode(ISD::SIGN_EXTEND, SDLoc(N), VT, X);
AddToWorklist(X.getNode());
} else if (OrigXWidth > VTWidth) {
// To get the sign bit in the right place, we have to shift it right
// before truncating.
SDLoc DL(X);
X = DAG.getNode(ISD::SRL, DL,
X.getValueType(), X,
DAG.getConstant(OrigXWidth-VTWidth, DL,
X.getValueType()));
AddToWorklist(X.getNode());
X = DAG.getNode(ISD::TRUNCATE, SDLoc(X), VT, X);
AddToWorklist(X.getNode());
}
if (N0.getValueType() == MVT::ppcf128 && !LegalTypes) {
APInt SignBit = APInt::getSignMask(VT.getSizeInBits() / 2);
SDValue Cst = DAG.getBitcast(VT, N0.getOperand(0));
AddToWorklist(Cst.getNode());
SDValue X = DAG.getBitcast(VT, N0.getOperand(1));
AddToWorklist(X.getNode());
SDValue XorResult = DAG.getNode(ISD::XOR, SDLoc(N0), VT, Cst, X);
AddToWorklist(XorResult.getNode());
SDValue XorResult64 = DAG.getNode(
ISD::EXTRACT_ELEMENT, SDLoc(XorResult), MVT::i64, XorResult,
DAG.getIntPtrConstant(getPPCf128HiElementSelector(DAG),
SDLoc(XorResult)));
AddToWorklist(XorResult64.getNode());
SDValue FlipBit =
DAG.getNode(ISD::AND, SDLoc(XorResult64), MVT::i64, XorResult64,
DAG.getConstant(SignBit, SDLoc(XorResult64), MVT::i64));
AddToWorklist(FlipBit.getNode());
SDValue FlipBits =
DAG.getNode(ISD::BUILD_PAIR, SDLoc(N0), VT, FlipBit, FlipBit);
AddToWorklist(FlipBits.getNode());
return DAG.getNode(ISD::XOR, SDLoc(N), VT, Cst, FlipBits);
}
APInt SignBit = APInt::getSignMask(VT.getSizeInBits());
X = DAG.getNode(ISD::AND, SDLoc(X), VT,
X, DAG.getConstant(SignBit, SDLoc(X), VT));
AddToWorklist(X.getNode());
SDValue Cst = DAG.getBitcast(VT, N0.getOperand(0));
Cst = DAG.getNode(ISD::AND, SDLoc(Cst), VT,
Cst, DAG.getConstant(~SignBit, SDLoc(Cst), VT));
AddToWorklist(Cst.getNode());
return DAG.getNode(ISD::OR, SDLoc(N), VT, X, Cst);
}
}
// bitconvert(build_pair(ld, ld)) -> ld iff load locations are consecutive.
if (N0.getOpcode() == ISD::BUILD_PAIR)
if (SDValue CombineLD = CombineConsecutiveLoads(N0.getNode(), VT))
return CombineLD;
// Remove double bitcasts from shuffles - this is often a legacy of
// XformToShuffleWithZero being used to combine bitmaskings (of
// float vectors bitcast to integer vectors) into shuffles.
// bitcast(shuffle(bitcast(s0),bitcast(s1))) -> shuffle(s0,s1)
if (Level < AfterLegalizeDAG && TLI.isTypeLegal(VT) && VT.isVector() &&
N0->getOpcode() == ISD::VECTOR_SHUFFLE && N0.hasOneUse() &&
VT.getVectorNumElements() >= N0.getValueType().getVectorNumElements() &&
!(VT.getVectorNumElements() % N0.getValueType().getVectorNumElements())) {
ShuffleVectorSDNode *SVN = cast<ShuffleVectorSDNode>(N0);
// If operands are a bitcast, peek through if it casts the original VT.
// If operands are a constant, just bitcast back to original VT.
auto PeekThroughBitcast = [&](SDValue Op) {
if (Op.getOpcode() == ISD::BITCAST &&
Op.getOperand(0).getValueType() == VT)
return SDValue(Op.getOperand(0));
if (Op.isUndef() || isAnyConstantBuildVector(Op))
return DAG.getBitcast(VT, Op);
return SDValue();
};
// FIXME: If either input vector is bitcast, try to convert the shuffle to
// the result type of this bitcast. This would eliminate at least one
// bitcast. See the transform in InstCombine.
SDValue SV0 = PeekThroughBitcast(N0->getOperand(0));
SDValue SV1 = PeekThroughBitcast(N0->getOperand(1));
if (!(SV0 && SV1))
return SDValue();
int MaskScale =
VT.getVectorNumElements() / N0.getValueType().getVectorNumElements();
SmallVector<int, 8> NewMask;
for (int M : SVN->getMask())
for (int i = 0; i != MaskScale; ++i)
NewMask.push_back(M < 0 ? -1 : M * MaskScale + i);
SDValue LegalShuffle =
TLI.buildLegalVectorShuffle(VT, SDLoc(N), SV0, SV1, NewMask, DAG);
if (LegalShuffle)
return LegalShuffle;
}
return SDValue();
}
SDValue DAGCombiner::visitBUILD_PAIR(SDNode *N) {
EVT VT = N->getValueType(0);
return CombineConsecutiveLoads(N, VT);
}
SDValue DAGCombiner::visitFREEZE(SDNode *N) {
SDValue N0 = N->getOperand(0);
if (DAG.isGuaranteedNotToBeUndefOrPoison(N0, /*PoisonOnly*/ false))
return N0;
// Fold freeze(bitcast(x)) -> bitcast(freeze(x)).
// TODO: Replace with pushFreezeToPreventPoisonFromPropagating fold.
if (N0.getOpcode() == ISD::BITCAST)
return DAG.getBitcast(N->getValueType(0),
DAG.getNode(ISD::FREEZE, SDLoc(N0),
N0.getOperand(0).getValueType(),
N0.getOperand(0)));
return SDValue();
}
/// We know that BV is a build_vector node with Constant, ConstantFP or Undef
/// operands. DstEltVT indicates the destination element value type.
SDValue DAGCombiner::
ConstantFoldBITCASTofBUILD_VECTOR(SDNode *BV, EVT DstEltVT) {
EVT SrcEltVT = BV->getValueType(0).getVectorElementType();
// If this is already the right type, we're done.
if (SrcEltVT == DstEltVT) return SDValue(BV, 0);
unsigned SrcBitSize = SrcEltVT.getSizeInBits();
unsigned DstBitSize = DstEltVT.getSizeInBits();
// If this is a conversion of N elements of one type to N elements of another
// type, convert each element. This handles FP<->INT cases.
if (SrcBitSize == DstBitSize) {
SmallVector<SDValue, 8> Ops;
for (SDValue Op : BV->op_values()) {
// If the vector element type is not legal, the BUILD_VECTOR operands
// are promoted and implicitly truncated. Make that explicit here.
if (Op.getValueType() != SrcEltVT)
Op = DAG.getNode(ISD::TRUNCATE, SDLoc(BV), SrcEltVT, Op);
Ops.push_back(DAG.getBitcast(DstEltVT, Op));
AddToWorklist(Ops.back().getNode());
}
EVT VT = EVT::getVectorVT(*DAG.getContext(), DstEltVT,
BV->getValueType(0).getVectorNumElements());
return DAG.getBuildVector(VT, SDLoc(BV), Ops);
}
// Otherwise, we're growing or shrinking the elements. To avoid having to
// handle annoying details of growing/shrinking FP values, we convert them to
// int first.
if (SrcEltVT.isFloatingPoint()) {
// Convert the input float vector to a int vector where the elements are the
// same sizes.
EVT IntVT = EVT::getIntegerVT(*DAG.getContext(), SrcEltVT.getSizeInBits());
BV = ConstantFoldBITCASTofBUILD_VECTOR(BV, IntVT).getNode();
SrcEltVT = IntVT;
}
// Now we know the input is an integer vector. If the output is a FP type,
// convert to integer first, then to FP of the right size.
if (DstEltVT.isFloatingPoint()) {
EVT TmpVT = EVT::getIntegerVT(*DAG.getContext(), DstEltVT.getSizeInBits());
SDNode *Tmp = ConstantFoldBITCASTofBUILD_VECTOR(BV, TmpVT).getNode();
// Next, convert to FP elements of the same size.
return ConstantFoldBITCASTofBUILD_VECTOR(Tmp, DstEltVT);
}
// Okay, we know the src/dst types are both integers of differing types.
assert(SrcEltVT.isInteger() && DstEltVT.isInteger());
// TODO: Should ConstantFoldBITCASTofBUILD_VECTOR always take a
// BuildVectorSDNode?
auto *BVN = cast<BuildVectorSDNode>(BV);
// Extract the constant raw bit data.
BitVector UndefElements;
SmallVector<APInt> RawBits;
bool IsLE = DAG.getDataLayout().isLittleEndian();
if (!BVN->getConstantRawBits(IsLE, DstBitSize, RawBits, UndefElements))
return SDValue();
SDLoc DL(BV);
SmallVector<SDValue, 8> Ops;
for (unsigned I = 0, E = RawBits.size(); I != E; ++I) {
if (UndefElements[I])
Ops.push_back(DAG.getUNDEF(DstEltVT));
else
Ops.push_back(DAG.getConstant(RawBits[I], DL, DstEltVT));
}
EVT VT = EVT::getVectorVT(*DAG.getContext(), DstEltVT, Ops.size());
return DAG.getBuildVector(VT, DL, Ops);
}
// Returns true if floating point contraction is allowed on the FMUL-SDValue
// `N`
static bool isContractableFMUL(const TargetOptions &Options, SDValue N) {
assert(N.getOpcode() == ISD::FMUL);
return Options.AllowFPOpFusion == FPOpFusion::Fast || Options.UnsafeFPMath ||
N->getFlags().hasAllowContract();
}
// Returns true if `N` can assume no infinities involved in its computation.
static bool hasNoInfs(const TargetOptions &Options, SDValue N) {
return Options.NoInfsFPMath || N->getFlags().hasNoInfs();
}
/// Try to perform FMA combining on a given FADD node.
SDValue DAGCombiner::visitFADDForFMACombine(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
SDLoc SL(N);
const TargetOptions &Options = DAG.getTarget().Options;
// Floating-point multiply-add with intermediate rounding.
bool HasFMAD = (LegalOperations && TLI.isFMADLegal(DAG, N));
// Floating-point multiply-add without intermediate rounding.
bool HasFMA =
TLI.isFMAFasterThanFMulAndFAdd(DAG.getMachineFunction(), VT) &&
(!LegalOperations || TLI.isOperationLegalOrCustom(ISD::FMA, VT));
// No valid opcode, do not combine.
if (!HasFMAD && !HasFMA)
return SDValue();
bool CanReassociate =
Options.UnsafeFPMath || N->getFlags().hasAllowReassociation();
bool AllowFusionGlobally = (Options.AllowFPOpFusion == FPOpFusion::Fast ||
Options.UnsafeFPMath || HasFMAD);
// If the addition is not contractable, do not combine.
if (!AllowFusionGlobally && !N->getFlags().hasAllowContract())
return SDValue();
if (TLI.generateFMAsInMachineCombiner(VT, OptLevel))
return SDValue();
// Always prefer FMAD to FMA for precision.
unsigned PreferredFusedOpcode = HasFMAD ? ISD::FMAD : ISD::FMA;
bool Aggressive = TLI.enableAggressiveFMAFusion(VT);
auto isFusedOp = [&](SDValue N) {
unsigned Opcode = N.getOpcode();
return Opcode == ISD::FMA || Opcode == ISD::FMAD;
};
// Is the node an FMUL and contractable either due to global flags or
// SDNodeFlags.
auto isContractableFMUL = [AllowFusionGlobally](SDValue N) {
if (N.getOpcode() != ISD::FMUL)
return false;
return AllowFusionGlobally || N->getFlags().hasAllowContract();
};
// If we have two choices trying to fold (fadd (fmul u, v), (fmul x, y)),
// prefer to fold the multiply with fewer uses.
if (Aggressive && isContractableFMUL(N0) && isContractableFMUL(N1)) {
if (N0->use_size() > N1->use_size())
std::swap(N0, N1);
}
// fold (fadd (fmul x, y), z) -> (fma x, y, z)
if (isContractableFMUL(N0) && (Aggressive || N0->hasOneUse())) {
return DAG.getNode(PreferredFusedOpcode, SL, VT, N0.getOperand(0),
N0.getOperand(1), N1);
}
// fold (fadd x, (fmul y, z)) -> (fma y, z, x)
// Note: Commutes FADD operands.
if (isContractableFMUL(N1) && (Aggressive || N1->hasOneUse())) {
return DAG.getNode(PreferredFusedOpcode, SL, VT, N1.getOperand(0),
N1.getOperand(1), N0);
}
// fadd (fma A, B, (fmul C, D)), E --> fma A, B, (fma C, D, E)
// fadd E, (fma A, B, (fmul C, D)) --> fma A, B, (fma C, D, E)
// This requires reassociation because it changes the order of operations.
SDValue FMA, E;
if (CanReassociate && isFusedOp(N0) &&
N0.getOperand(2).getOpcode() == ISD::FMUL && N0.hasOneUse() &&
N0.getOperand(2).hasOneUse()) {
FMA = N0;
E = N1;
} else if (CanReassociate && isFusedOp(N1) &&
N1.getOperand(2).getOpcode() == ISD::FMUL && N1.hasOneUse() &&
N1.getOperand(2).hasOneUse()) {
FMA = N1;
E = N0;
}
if (FMA && E) {
SDValue A = FMA.getOperand(0);
SDValue B = FMA.getOperand(1);
SDValue C = FMA.getOperand(2).getOperand(0);
SDValue D = FMA.getOperand(2).getOperand(1);
SDValue CDE = DAG.getNode(PreferredFusedOpcode, SL, VT, C, D, E);
return DAG.getNode(PreferredFusedOpcode, SL, VT, A, B, CDE);
}
// Look through FP_EXTEND nodes to do more combining.
// fold (fadd (fpext (fmul x, y)), z) -> (fma (fpext x), (fpext y), z)
if (N0.getOpcode() == ISD::FP_EXTEND) {
SDValue N00 = N0.getOperand(0);
if (isContractableFMUL(N00) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N00.getValueType())) {
return DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, N00.getOperand(0)),
DAG.getNode(ISD::FP_EXTEND, SL, VT, N00.getOperand(1)),
N1);
}
}
// fold (fadd x, (fpext (fmul y, z))) -> (fma (fpext y), (fpext z), x)
// Note: Commutes FADD operands.
if (N1.getOpcode() == ISD::FP_EXTEND) {
SDValue N10 = N1.getOperand(0);
if (isContractableFMUL(N10) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N10.getValueType())) {
return DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, N10.getOperand(0)),
DAG.getNode(ISD::FP_EXTEND, SL, VT, N10.getOperand(1)),
N0);
}
}
// More folding opportunities when target permits.
if (Aggressive) {
// fold (fadd (fma x, y, (fpext (fmul u, v))), z)
// -> (fma x, y, (fma (fpext u), (fpext v), z))
auto FoldFAddFMAFPExtFMul = [&](SDValue X, SDValue Y, SDValue U, SDValue V,
SDValue Z) {
return DAG.getNode(PreferredFusedOpcode, SL, VT, X, Y,
DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, U),
DAG.getNode(ISD::FP_EXTEND, SL, VT, V),
Z));
};
if (isFusedOp(N0)) {
SDValue N02 = N0.getOperand(2);
if (N02.getOpcode() == ISD::FP_EXTEND) {
SDValue N020 = N02.getOperand(0);
if (isContractableFMUL(N020) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N020.getValueType())) {
return FoldFAddFMAFPExtFMul(N0.getOperand(0), N0.getOperand(1),
N020.getOperand(0), N020.getOperand(1),
N1);
}
}
}
// fold (fadd (fpext (fma x, y, (fmul u, v))), z)
// -> (fma (fpext x), (fpext y), (fma (fpext u), (fpext v), z))
// FIXME: This turns two single-precision and one double-precision
// operation into two double-precision operations, which might not be
// interesting for all targets, especially GPUs.
auto FoldFAddFPExtFMAFMul = [&](SDValue X, SDValue Y, SDValue U, SDValue V,
SDValue Z) {
return DAG.getNode(
PreferredFusedOpcode, SL, VT, DAG.getNode(ISD::FP_EXTEND, SL, VT, X),
DAG.getNode(ISD::FP_EXTEND, SL, VT, Y),
DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, U),
DAG.getNode(ISD::FP_EXTEND, SL, VT, V), Z));
};
if (N0.getOpcode() == ISD::FP_EXTEND) {
SDValue N00 = N0.getOperand(0);
if (isFusedOp(N00)) {
SDValue N002 = N00.getOperand(2);
if (isContractableFMUL(N002) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N00.getValueType())) {
return FoldFAddFPExtFMAFMul(N00.getOperand(0), N00.getOperand(1),
N002.getOperand(0), N002.getOperand(1),
N1);
}
}
}
// fold (fadd x, (fma y, z, (fpext (fmul u, v)))
// -> (fma y, z, (fma (fpext u), (fpext v), x))
if (isFusedOp(N1)) {
SDValue N12 = N1.getOperand(2);
if (N12.getOpcode() == ISD::FP_EXTEND) {
SDValue N120 = N12.getOperand(0);
if (isContractableFMUL(N120) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N120.getValueType())) {
return FoldFAddFMAFPExtFMul(N1.getOperand(0), N1.getOperand(1),
N120.getOperand(0), N120.getOperand(1),
N0);
}
}
}
// fold (fadd x, (fpext (fma y, z, (fmul u, v)))
// -> (fma (fpext y), (fpext z), (fma (fpext u), (fpext v), x))
// FIXME: This turns two single-precision and one double-precision
// operation into two double-precision operations, which might not be
// interesting for all targets, especially GPUs.
if (N1.getOpcode() == ISD::FP_EXTEND) {
SDValue N10 = N1.getOperand(0);
if (isFusedOp(N10)) {
SDValue N102 = N10.getOperand(2);
if (isContractableFMUL(N102) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N10.getValueType())) {
return FoldFAddFPExtFMAFMul(N10.getOperand(0), N10.getOperand(1),
N102.getOperand(0), N102.getOperand(1),
N0);
}
}
}
}
return SDValue();
}
/// Try to perform FMA combining on a given FSUB node.
SDValue DAGCombiner::visitFSUBForFMACombine(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
SDLoc SL(N);
const TargetOptions &Options = DAG.getTarget().Options;
// Floating-point multiply-add with intermediate rounding.
bool HasFMAD = (LegalOperations && TLI.isFMADLegal(DAG, N));
// Floating-point multiply-add without intermediate rounding.
bool HasFMA =
TLI.isFMAFasterThanFMulAndFAdd(DAG.getMachineFunction(), VT) &&
(!LegalOperations || TLI.isOperationLegalOrCustom(ISD::FMA, VT));
// No valid opcode, do not combine.
if (!HasFMAD && !HasFMA)
return SDValue();
const SDNodeFlags Flags = N->getFlags();
bool AllowFusionGlobally = (Options.AllowFPOpFusion == FPOpFusion::Fast ||
Options.UnsafeFPMath || HasFMAD);
// If the subtraction is not contractable, do not combine.
if (!AllowFusionGlobally && !N->getFlags().hasAllowContract())
return SDValue();
if (TLI.generateFMAsInMachineCombiner(VT, OptLevel))
return SDValue();
// Always prefer FMAD to FMA for precision.
unsigned PreferredFusedOpcode = HasFMAD ? ISD::FMAD : ISD::FMA;
bool Aggressive = TLI.enableAggressiveFMAFusion(VT);
bool NoSignedZero = Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros();
// Is the node an FMUL and contractable either due to global flags or
// SDNodeFlags.
auto isContractableFMUL = [AllowFusionGlobally](SDValue N) {
if (N.getOpcode() != ISD::FMUL)
return false;
return AllowFusionGlobally || N->getFlags().hasAllowContract();
};
// fold (fsub (fmul x, y), z) -> (fma x, y, (fneg z))
auto tryToFoldXYSubZ = [&](SDValue XY, SDValue Z) {
if (isContractableFMUL(XY) && (Aggressive || XY->hasOneUse())) {
return DAG.getNode(PreferredFusedOpcode, SL, VT, XY.getOperand(0),
XY.getOperand(1), DAG.getNode(ISD::FNEG, SL, VT, Z));
}
return SDValue();
};
// fold (fsub x, (fmul y, z)) -> (fma (fneg y), z, x)
// Note: Commutes FSUB operands.
auto tryToFoldXSubYZ = [&](SDValue X, SDValue YZ) {
if (isContractableFMUL(YZ) && (Aggressive || YZ->hasOneUse())) {
return DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FNEG, SL, VT, YZ.getOperand(0)),
YZ.getOperand(1), X);
}
return SDValue();
};
// If we have two choices trying to fold (fsub (fmul u, v), (fmul x, y)),
// prefer to fold the multiply with fewer uses.
if (isContractableFMUL(N0) && isContractableFMUL(N1) &&
(N0->use_size() > N1->use_size())) {
// fold (fsub (fmul a, b), (fmul c, d)) -> (fma (fneg c), d, (fmul a, b))
if (SDValue V = tryToFoldXSubYZ(N0, N1))
return V;
// fold (fsub (fmul a, b), (fmul c, d)) -> (fma a, b, (fneg (fmul c, d)))
if (SDValue V = tryToFoldXYSubZ(N0, N1))
return V;
} else {
// fold (fsub (fmul x, y), z) -> (fma x, y, (fneg z))
if (SDValue V = tryToFoldXYSubZ(N0, N1))
return V;
// fold (fsub x, (fmul y, z)) -> (fma (fneg y), z, x)
if (SDValue V = tryToFoldXSubYZ(N0, N1))
return V;
}
// fold (fsub (fneg (fmul, x, y)), z) -> (fma (fneg x), y, (fneg z))
if (N0.getOpcode() == ISD::FNEG && isContractableFMUL(N0.getOperand(0)) &&
(Aggressive || (N0->hasOneUse() && N0.getOperand(0).hasOneUse()))) {
SDValue N00 = N0.getOperand(0).getOperand(0);
SDValue N01 = N0.getOperand(0).getOperand(1);
return DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FNEG, SL, VT, N00), N01,
DAG.getNode(ISD::FNEG, SL, VT, N1));
}
// Look through FP_EXTEND nodes to do more combining.
// fold (fsub (fpext (fmul x, y)), z)
// -> (fma (fpext x), (fpext y), (fneg z))
if (N0.getOpcode() == ISD::FP_EXTEND) {
SDValue N00 = N0.getOperand(0);
if (isContractableFMUL(N00) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N00.getValueType())) {
return DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, N00.getOperand(0)),
DAG.getNode(ISD::FP_EXTEND, SL, VT, N00.getOperand(1)),
DAG.getNode(ISD::FNEG, SL, VT, N1));
}
}
// fold (fsub x, (fpext (fmul y, z)))
// -> (fma (fneg (fpext y)), (fpext z), x)
// Note: Commutes FSUB operands.
if (N1.getOpcode() == ISD::FP_EXTEND) {
SDValue N10 = N1.getOperand(0);
if (isContractableFMUL(N10) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N10.getValueType())) {
return DAG.getNode(
PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FNEG, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, N10.getOperand(0))),
DAG.getNode(ISD::FP_EXTEND, SL, VT, N10.getOperand(1)), N0);
}
}
// fold (fsub (fpext (fneg (fmul, x, y))), z)
// -> (fneg (fma (fpext x), (fpext y), z))
// Note: This could be removed with appropriate canonicalization of the
// input expression into (fneg (fadd (fpext (fmul, x, y)), z). However, the
// orthogonal flags -fp-contract=fast and -enable-unsafe-fp-math prevent
// from implementing the canonicalization in visitFSUB.
if (N0.getOpcode() == ISD::FP_EXTEND) {
SDValue N00 = N0.getOperand(0);
if (N00.getOpcode() == ISD::FNEG) {
SDValue N000 = N00.getOperand(0);
if (isContractableFMUL(N000) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N00.getValueType())) {
return DAG.getNode(
ISD::FNEG, SL, VT,
DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, N000.getOperand(0)),
DAG.getNode(ISD::FP_EXTEND, SL, VT, N000.getOperand(1)),
N1));
}
}
}
// fold (fsub (fneg (fpext (fmul, x, y))), z)
// -> (fneg (fma (fpext x)), (fpext y), z)
// Note: This could be removed with appropriate canonicalization of the
// input expression into (fneg (fadd (fpext (fmul, x, y)), z). However, the
// orthogonal flags -fp-contract=fast and -enable-unsafe-fp-math prevent
// from implementing the canonicalization in visitFSUB.
if (N0.getOpcode() == ISD::FNEG) {
SDValue N00 = N0.getOperand(0);
if (N00.getOpcode() == ISD::FP_EXTEND) {
SDValue N000 = N00.getOperand(0);
if (isContractableFMUL(N000) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N000.getValueType())) {
return DAG.getNode(
ISD::FNEG, SL, VT,
DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, N000.getOperand(0)),
DAG.getNode(ISD::FP_EXTEND, SL, VT, N000.getOperand(1)),
N1));
}
}
}
auto isReassociable = [Options](SDNode *N) {
return Options.UnsafeFPMath || N->getFlags().hasAllowReassociation();
};
auto isContractableAndReassociableFMUL = [isContractableFMUL,
isReassociable](SDValue N) {
return isContractableFMUL(N) && isReassociable(N.getNode());
};
auto isFusedOp = [&](SDValue N) {
unsigned Opcode = N.getOpcode();
return Opcode == ISD::FMA || Opcode == ISD::FMAD;
};
// More folding opportunities when target permits.
if (Aggressive && isReassociable(N)) {
bool CanFuse = Options.UnsafeFPMath || N->getFlags().hasAllowContract();
// fold (fsub (fma x, y, (fmul u, v)), z)
// -> (fma x, y (fma u, v, (fneg z)))
if (CanFuse && isFusedOp(N0) &&
isContractableAndReassociableFMUL(N0.getOperand(2)) &&
N0->hasOneUse() && N0.getOperand(2)->hasOneUse()) {
return DAG.getNode(PreferredFusedOpcode, SL, VT, N0.getOperand(0),
N0.getOperand(1),
DAG.getNode(PreferredFusedOpcode, SL, VT,
N0.getOperand(2).getOperand(0),
N0.getOperand(2).getOperand(1),
DAG.getNode(ISD::FNEG, SL, VT, N1)));
}
// fold (fsub x, (fma y, z, (fmul u, v)))
// -> (fma (fneg y), z, (fma (fneg u), v, x))
if (CanFuse && isFusedOp(N1) &&
isContractableAndReassociableFMUL(N1.getOperand(2)) &&
N1->hasOneUse() && NoSignedZero) {
SDValue N20 = N1.getOperand(2).getOperand(0);
SDValue N21 = N1.getOperand(2).getOperand(1);
return DAG.getNode(
PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FNEG, SL, VT, N1.getOperand(0)), N1.getOperand(1),
DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FNEG, SL, VT, N20), N21, N0));
}
// fold (fsub (fma x, y, (fpext (fmul u, v))), z)
// -> (fma x, y (fma (fpext u), (fpext v), (fneg z)))
if (isFusedOp(N0) && N0->hasOneUse()) {
SDValue N02 = N0.getOperand(2);
if (N02.getOpcode() == ISD::FP_EXTEND) {
SDValue N020 = N02.getOperand(0);
if (isContractableAndReassociableFMUL(N020) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N020.getValueType())) {
return DAG.getNode(
PreferredFusedOpcode, SL, VT, N0.getOperand(0), N0.getOperand(1),
DAG.getNode(
PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, N020.getOperand(0)),
DAG.getNode(ISD::FP_EXTEND, SL, VT, N020.getOperand(1)),
DAG.getNode(ISD::FNEG, SL, VT, N1)));
}
}
}
// fold (fsub (fpext (fma x, y, (fmul u, v))), z)
// -> (fma (fpext x), (fpext y),
// (fma (fpext u), (fpext v), (fneg z)))
// FIXME: This turns two single-precision and one double-precision
// operation into two double-precision operations, which might not be
// interesting for all targets, especially GPUs.
if (N0.getOpcode() == ISD::FP_EXTEND) {
SDValue N00 = N0.getOperand(0);
if (isFusedOp(N00)) {
SDValue N002 = N00.getOperand(2);
if (isContractableAndReassociableFMUL(N002) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N00.getValueType())) {
return DAG.getNode(
PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, N00.getOperand(0)),
DAG.getNode(ISD::FP_EXTEND, SL, VT, N00.getOperand(1)),
DAG.getNode(
PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, N002.getOperand(0)),
DAG.getNode(ISD::FP_EXTEND, SL, VT, N002.getOperand(1)),
DAG.getNode(ISD::FNEG, SL, VT, N1)));
}
}
}
// fold (fsub x, (fma y, z, (fpext (fmul u, v))))
// -> (fma (fneg y), z, (fma (fneg (fpext u)), (fpext v), x))
if (isFusedOp(N1) && N1.getOperand(2).getOpcode() == ISD::FP_EXTEND &&
N1->hasOneUse()) {
SDValue N120 = N1.getOperand(2).getOperand(0);
if (isContractableAndReassociableFMUL(N120) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
N120.getValueType())) {
SDValue N1200 = N120.getOperand(0);
SDValue N1201 = N120.getOperand(1);
return DAG.getNode(
PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FNEG, SL, VT, N1.getOperand(0)), N1.getOperand(1),
DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FNEG, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, N1200)),
DAG.getNode(ISD::FP_EXTEND, SL, VT, N1201), N0));
}
}
// fold (fsub x, (fpext (fma y, z, (fmul u, v))))
// -> (fma (fneg (fpext y)), (fpext z),
// (fma (fneg (fpext u)), (fpext v), x))
// FIXME: This turns two single-precision and one double-precision
// operation into two double-precision operations, which might not be
// interesting for all targets, especially GPUs.
if (N1.getOpcode() == ISD::FP_EXTEND && isFusedOp(N1.getOperand(0))) {
SDValue CvtSrc = N1.getOperand(0);
SDValue N100 = CvtSrc.getOperand(0);
SDValue N101 = CvtSrc.getOperand(1);
SDValue N102 = CvtSrc.getOperand(2);
if (isContractableAndReassociableFMUL(N102) &&
TLI.isFPExtFoldable(DAG, PreferredFusedOpcode, VT,
CvtSrc.getValueType())) {
SDValue N1020 = N102.getOperand(0);
SDValue N1021 = N102.getOperand(1);
return DAG.getNode(
PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FNEG, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, N100)),
DAG.getNode(ISD::FP_EXTEND, SL, VT, N101),
DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FNEG, SL, VT,
DAG.getNode(ISD::FP_EXTEND, SL, VT, N1020)),
DAG.getNode(ISD::FP_EXTEND, SL, VT, N1021), N0));
}
}
}
return SDValue();
}
/// Try to perform FMA combining on a given FMUL node based on the distributive
/// law x * (y + 1) = x * y + x and variants thereof (commuted versions,
/// subtraction instead of addition).
SDValue DAGCombiner::visitFMULForFMADistributiveCombine(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
SDLoc SL(N);
assert(N->getOpcode() == ISD::FMUL && "Expected FMUL Operation");
const TargetOptions &Options = DAG.getTarget().Options;
// The transforms below are incorrect when x == 0 and y == inf, because the
// intermediate multiplication produces a nan.
SDValue FAdd = N0.getOpcode() == ISD::FADD ? N0 : N1;
if (!hasNoInfs(Options, FAdd))
return SDValue();
// Floating-point multiply-add without intermediate rounding.
bool HasFMA =
isContractableFMUL(Options, SDValue(N, 0)) &&
TLI.isFMAFasterThanFMulAndFAdd(DAG.getMachineFunction(), VT) &&
(!LegalOperations || TLI.isOperationLegalOrCustom(ISD::FMA, VT));
// Floating-point multiply-add with intermediate rounding. This can result
// in a less precise result due to the changed rounding order.
bool HasFMAD = Options.UnsafeFPMath &&
(LegalOperations && TLI.isFMADLegal(DAG, N));
// No valid opcode, do not combine.
if (!HasFMAD && !HasFMA)
return SDValue();
// Always prefer FMAD to FMA for precision.
unsigned PreferredFusedOpcode = HasFMAD ? ISD::FMAD : ISD::FMA;
bool Aggressive = TLI.enableAggressiveFMAFusion(VT);
// fold (fmul (fadd x0, +1.0), y) -> (fma x0, y, y)
// fold (fmul (fadd x0, -1.0), y) -> (fma x0, y, (fneg y))
auto FuseFADD = [&](SDValue X, SDValue Y) {
if (X.getOpcode() == ISD::FADD && (Aggressive || X->hasOneUse())) {
if (auto *C = isConstOrConstSplatFP(X.getOperand(1), true)) {
if (C->isExactlyValue(+1.0))
return DAG.getNode(PreferredFusedOpcode, SL, VT, X.getOperand(0), Y,
Y);
if (C->isExactlyValue(-1.0))
return DAG.getNode(PreferredFusedOpcode, SL, VT, X.getOperand(0), Y,
DAG.getNode(ISD::FNEG, SL, VT, Y));
}
}
return SDValue();
};
if (SDValue FMA = FuseFADD(N0, N1))
return FMA;
if (SDValue FMA = FuseFADD(N1, N0))
return FMA;
// fold (fmul (fsub +1.0, x1), y) -> (fma (fneg x1), y, y)
// fold (fmul (fsub -1.0, x1), y) -> (fma (fneg x1), y, (fneg y))
// fold (fmul (fsub x0, +1.0), y) -> (fma x0, y, (fneg y))
// fold (fmul (fsub x0, -1.0), y) -> (fma x0, y, y)
auto FuseFSUB = [&](SDValue X, SDValue Y) {
if (X.getOpcode() == ISD::FSUB && (Aggressive || X->hasOneUse())) {
if (auto *C0 = isConstOrConstSplatFP(X.getOperand(0), true)) {
if (C0->isExactlyValue(+1.0))
return DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FNEG, SL, VT, X.getOperand(1)), Y,
Y);
if (C0->isExactlyValue(-1.0))
return DAG.getNode(PreferredFusedOpcode, SL, VT,
DAG.getNode(ISD::FNEG, SL, VT, X.getOperand(1)), Y,
DAG.getNode(ISD::FNEG, SL, VT, Y));
}
if (auto *C1 = isConstOrConstSplatFP(X.getOperand(1), true)) {
if (C1->isExactlyValue(+1.0))
return DAG.getNode(PreferredFusedOpcode, SL, VT, X.getOperand(0), Y,
DAG.getNode(ISD::FNEG, SL, VT, Y));
if (C1->isExactlyValue(-1.0))
return DAG.getNode(PreferredFusedOpcode, SL, VT, X.getOperand(0), Y,
Y);
}
}
return SDValue();
};
if (SDValue FMA = FuseFSUB(N0, N1))
return FMA;
if (SDValue FMA = FuseFSUB(N1, N0))
return FMA;
return SDValue();
}
SDValue DAGCombiner::visitFADD(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
bool N0CFP = DAG.isConstantFPBuildVectorOrConstantFP(N0);
bool N1CFP = DAG.isConstantFPBuildVectorOrConstantFP(N1);
EVT VT = N->getValueType(0);
SDLoc DL(N);
const TargetOptions &Options = DAG.getTarget().Options;
SDNodeFlags Flags = N->getFlags();
SelectionDAG::FlagInserter FlagsInserter(DAG, N);
if (SDValue R = DAG.simplifyFPBinop(N->getOpcode(), N0, N1, Flags))
return R;
// fold (fadd c1, c2) -> c1 + c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::FADD, DL, VT, {N0, N1}))
return C;
// canonicalize constant to RHS
if (N0CFP && !N1CFP)
return DAG.getNode(ISD::FADD, DL, VT, N1, N0);
// fold vector ops
if (VT.isVector())
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
// N0 + -0.0 --> N0 (also allowed with +0.0 and fast-math)
ConstantFPSDNode *N1C = isConstOrConstSplatFP(N1, true);
if (N1C && N1C->isZero())
if (N1C->isNegative() || Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros())
return N0;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
// fold (fadd A, (fneg B)) -> (fsub A, B)
if (!LegalOperations || TLI.isOperationLegalOrCustom(ISD::FSUB, VT))
if (SDValue NegN1 = TLI.getCheaperNegatedExpression(
N1, DAG, LegalOperations, ForCodeSize))
return DAG.getNode(ISD::FSUB, DL, VT, N0, NegN1);
// fold (fadd (fneg A), B) -> (fsub B, A)
if (!LegalOperations || TLI.isOperationLegalOrCustom(ISD::FSUB, VT))
if (SDValue NegN0 = TLI.getCheaperNegatedExpression(
N0, DAG, LegalOperations, ForCodeSize))
return DAG.getNode(ISD::FSUB, DL, VT, N1, NegN0);
auto isFMulNegTwo = [](SDValue FMul) {
if (!FMul.hasOneUse() || FMul.getOpcode() != ISD::FMUL)
return false;
auto *C = isConstOrConstSplatFP(FMul.getOperand(1), true);
return C && C->isExactlyValue(-2.0);
};
// fadd (fmul B, -2.0), A --> fsub A, (fadd B, B)
if (isFMulNegTwo(N0)) {
SDValue B = N0.getOperand(0);
SDValue Add = DAG.getNode(ISD::FADD, DL, VT, B, B);
return DAG.getNode(ISD::FSUB, DL, VT, N1, Add);
}
// fadd A, (fmul B, -2.0) --> fsub A, (fadd B, B)
if (isFMulNegTwo(N1)) {
SDValue B = N1.getOperand(0);
SDValue Add = DAG.getNode(ISD::FADD, DL, VT, B, B);
return DAG.getNode(ISD::FSUB, DL, VT, N0, Add);
}
// No FP constant should be created after legalization as Instruction
// Selection pass has a hard time dealing with FP constants.
bool AllowNewConst = (Level < AfterLegalizeDAG);
// If nnan is enabled, fold lots of things.
if ((Options.NoNaNsFPMath || Flags.hasNoNaNs()) && AllowNewConst) {
// If allowed, fold (fadd (fneg x), x) -> 0.0
if (N0.getOpcode() == ISD::FNEG && N0.getOperand(0) == N1)
return DAG.getConstantFP(0.0, DL, VT);
// If allowed, fold (fadd x, (fneg x)) -> 0.0
if (N1.getOpcode() == ISD::FNEG && N1.getOperand(0) == N0)
return DAG.getConstantFP(0.0, DL, VT);
}
// If 'unsafe math' or reassoc and nsz, fold lots of things.
// TODO: break out portions of the transformations below for which Unsafe is
// considered and which do not require both nsz and reassoc
if (((Options.UnsafeFPMath && Options.NoSignedZerosFPMath) ||
(Flags.hasAllowReassociation() && Flags.hasNoSignedZeros())) &&
AllowNewConst) {
// fadd (fadd x, c1), c2 -> fadd x, c1 + c2
if (N1CFP && N0.getOpcode() == ISD::FADD &&
DAG.isConstantFPBuildVectorOrConstantFP(N0.getOperand(1))) {
SDValue NewC = DAG.getNode(ISD::FADD, DL, VT, N0.getOperand(1), N1);
return DAG.getNode(ISD::FADD, DL, VT, N0.getOperand(0), NewC);
}
// We can fold chains of FADD's of the same value into multiplications.
// This transform is not safe in general because we are reducing the number
// of rounding steps.
if (TLI.isOperationLegalOrCustom(ISD::FMUL, VT) && !N0CFP && !N1CFP) {
if (N0.getOpcode() == ISD::FMUL) {
bool CFP00 = DAG.isConstantFPBuildVectorOrConstantFP(N0.getOperand(0));
bool CFP01 = DAG.isConstantFPBuildVectorOrConstantFP(N0.getOperand(1));
// (fadd (fmul x, c), x) -> (fmul x, c+1)
if (CFP01 && !CFP00 && N0.getOperand(0) == N1) {
SDValue NewCFP = DAG.getNode(ISD::FADD, DL, VT, N0.getOperand(1),
DAG.getConstantFP(1.0, DL, VT));
return DAG.getNode(ISD::FMUL, DL, VT, N1, NewCFP);
}
// (fadd (fmul x, c), (fadd x, x)) -> (fmul x, c+2)
if (CFP01 && !CFP00 && N1.getOpcode() == ISD::FADD &&
N1.getOperand(0) == N1.getOperand(1) &&
N0.getOperand(0) == N1.getOperand(0)) {
SDValue NewCFP = DAG.getNode(ISD::FADD, DL, VT, N0.getOperand(1),
DAG.getConstantFP(2.0, DL, VT));
return DAG.getNode(ISD::FMUL, DL, VT, N0.getOperand(0), NewCFP);
}
}
if (N1.getOpcode() == ISD::FMUL) {
bool CFP10 = DAG.isConstantFPBuildVectorOrConstantFP(N1.getOperand(0));
bool CFP11 = DAG.isConstantFPBuildVectorOrConstantFP(N1.getOperand(1));
// (fadd x, (fmul x, c)) -> (fmul x, c+1)
if (CFP11 && !CFP10 && N1.getOperand(0) == N0) {
SDValue NewCFP = DAG.getNode(ISD::FADD, DL, VT, N1.getOperand(1),
DAG.getConstantFP(1.0, DL, VT));
return DAG.getNode(ISD::FMUL, DL, VT, N0, NewCFP);
}
// (fadd (fadd x, x), (fmul x, c)) -> (fmul x, c+2)
if (CFP11 && !CFP10 && N0.getOpcode() == ISD::FADD &&
N0.getOperand(0) == N0.getOperand(1) &&
N1.getOperand(0) == N0.getOperand(0)) {
SDValue NewCFP = DAG.getNode(ISD::FADD, DL, VT, N1.getOperand(1),
DAG.getConstantFP(2.0, DL, VT));
return DAG.getNode(ISD::FMUL, DL, VT, N1.getOperand(0), NewCFP);
}
}
if (N0.getOpcode() == ISD::FADD) {
bool CFP00 = DAG.isConstantFPBuildVectorOrConstantFP(N0.getOperand(0));
// (fadd (fadd x, x), x) -> (fmul x, 3.0)
if (!CFP00 && N0.getOperand(0) == N0.getOperand(1) &&
(N0.getOperand(0) == N1)) {
return DAG.getNode(ISD::FMUL, DL, VT, N1,
DAG.getConstantFP(3.0, DL, VT));
}
}
if (N1.getOpcode() == ISD::FADD) {
bool CFP10 = DAG.isConstantFPBuildVectorOrConstantFP(N1.getOperand(0));
// (fadd x, (fadd x, x)) -> (fmul x, 3.0)
if (!CFP10 && N1.getOperand(0) == N1.getOperand(1) &&
N1.getOperand(0) == N0) {
return DAG.getNode(ISD::FMUL, DL, VT, N0,
DAG.getConstantFP(3.0, DL, VT));
}
}
// (fadd (fadd x, x), (fadd x, x)) -> (fmul x, 4.0)
if (N0.getOpcode() == ISD::FADD && N1.getOpcode() == ISD::FADD &&
N0.getOperand(0) == N0.getOperand(1) &&
N1.getOperand(0) == N1.getOperand(1) &&
N0.getOperand(0) == N1.getOperand(0)) {
return DAG.getNode(ISD::FMUL, DL, VT, N0.getOperand(0),
DAG.getConstantFP(4.0, DL, VT));
}
}
} // enable-unsafe-fp-math
// FADD -> FMA combines:
if (SDValue Fused = visitFADDForFMACombine(N)) {
AddToWorklist(Fused.getNode());
return Fused;
}
return SDValue();
}
SDValue DAGCombiner::visitSTRICT_FADD(SDNode *N) {
SDValue Chain = N->getOperand(0);
SDValue N0 = N->getOperand(1);
SDValue N1 = N->getOperand(2);
EVT VT = N->getValueType(0);
EVT ChainVT = N->getValueType(1);
SDLoc DL(N);
SelectionDAG::FlagInserter FlagsInserter(DAG, N);
// fold (strict_fadd A, (fneg B)) -> (strict_fsub A, B)
if (!LegalOperations || TLI.isOperationLegalOrCustom(ISD::STRICT_FSUB, VT))
if (SDValue NegN1 = TLI.getCheaperNegatedExpression(
N1, DAG, LegalOperations, ForCodeSize)) {
return DAG.getNode(ISD::STRICT_FSUB, DL, DAG.getVTList(VT, ChainVT),
{Chain, N0, NegN1});
}
// fold (strict_fadd (fneg A), B) -> (strict_fsub B, A)
if (!LegalOperations || TLI.isOperationLegalOrCustom(ISD::STRICT_FSUB, VT))
if (SDValue NegN0 = TLI.getCheaperNegatedExpression(
N0, DAG, LegalOperations, ForCodeSize)) {
return DAG.getNode(ISD::STRICT_FSUB, DL, DAG.getVTList(VT, ChainVT),
{Chain, N1, NegN0});
}
return SDValue();
}
SDValue DAGCombiner::visitFSUB(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
ConstantFPSDNode *N0CFP = isConstOrConstSplatFP(N0, true);
ConstantFPSDNode *N1CFP = isConstOrConstSplatFP(N1, true);
EVT VT = N->getValueType(0);
SDLoc DL(N);
const TargetOptions &Options = DAG.getTarget().Options;
const SDNodeFlags Flags = N->getFlags();
SelectionDAG::FlagInserter FlagsInserter(DAG, N);
if (SDValue R = DAG.simplifyFPBinop(N->getOpcode(), N0, N1, Flags))
return R;
// fold (fsub c1, c2) -> c1-c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::FSUB, DL, VT, {N0, N1}))
return C;
// fold vector ops
if (VT.isVector())
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
// (fsub A, 0) -> A
if (N1CFP && N1CFP->isZero()) {
if (!N1CFP->isNegative() || Options.NoSignedZerosFPMath ||
Flags.hasNoSignedZeros()) {
return N0;
}
}
if (N0 == N1) {
// (fsub x, x) -> 0.0
if (Options.NoNaNsFPMath || Flags.hasNoNaNs())
return DAG.getConstantFP(0.0f, DL, VT);
}
// (fsub -0.0, N1) -> -N1
if (N0CFP && N0CFP->isZero()) {
if (N0CFP->isNegative() ||
(Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros())) {
// We cannot replace an FSUB(+-0.0,X) with FNEG(X) when denormals are
// flushed to zero, unless all users treat denorms as zero (DAZ).
// FIXME: This transform will change the sign of a NaN and the behavior
// of a signaling NaN. It is only valid when a NoNaN flag is present.
DenormalMode DenormMode = DAG.getDenormalMode(VT);
if (DenormMode == DenormalMode::getIEEE()) {
if (SDValue NegN1 =
TLI.getNegatedExpression(N1, DAG, LegalOperations, ForCodeSize))
return NegN1;
if (!LegalOperations || TLI.isOperationLegal(ISD::FNEG, VT))
return DAG.getNode(ISD::FNEG, DL, VT, N1);
}
}
}
if (((Options.UnsafeFPMath && Options.NoSignedZerosFPMath) ||
(Flags.hasAllowReassociation() && Flags.hasNoSignedZeros())) &&
N1.getOpcode() == ISD::FADD) {
// X - (X + Y) -> -Y
if (N0 == N1->getOperand(0))
return DAG.getNode(ISD::FNEG, DL, VT, N1->getOperand(1));
// X - (Y + X) -> -Y
if (N0 == N1->getOperand(1))
return DAG.getNode(ISD::FNEG, DL, VT, N1->getOperand(0));
}
// fold (fsub A, (fneg B)) -> (fadd A, B)
if (SDValue NegN1 =
TLI.getNegatedExpression(N1, DAG, LegalOperations, ForCodeSize))
return DAG.getNode(ISD::FADD, DL, VT, N0, NegN1);
// FSUB -> FMA combines:
if (SDValue Fused = visitFSUBForFMACombine(N)) {
AddToWorklist(Fused.getNode());
return Fused;
}
return SDValue();
}
SDValue DAGCombiner::visitFMUL(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
ConstantFPSDNode *N1CFP = isConstOrConstSplatFP(N1, true);
EVT VT = N->getValueType(0);
SDLoc DL(N);
const TargetOptions &Options = DAG.getTarget().Options;
const SDNodeFlags Flags = N->getFlags();
SelectionDAG::FlagInserter FlagsInserter(DAG, N);
if (SDValue R = DAG.simplifyFPBinop(N->getOpcode(), N0, N1, Flags))
return R;
// fold (fmul c1, c2) -> c1*c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::FMUL, DL, VT, {N0, N1}))
return C;
// canonicalize constant to RHS
if (DAG.isConstantFPBuildVectorOrConstantFP(N0) &&
!DAG.isConstantFPBuildVectorOrConstantFP(N1))
return DAG.getNode(ISD::FMUL, DL, VT, N1, N0);
// fold vector ops
if (VT.isVector())
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
if (Options.UnsafeFPMath || Flags.hasAllowReassociation()) {
// fmul (fmul X, C1), C2 -> fmul X, C1 * C2
if (DAG.isConstantFPBuildVectorOrConstantFP(N1) &&
N0.getOpcode() == ISD::FMUL) {
SDValue N00 = N0.getOperand(0);
SDValue N01 = N0.getOperand(1);
// Avoid an infinite loop by making sure that N00 is not a constant
// (the inner multiply has not been constant folded yet).
if (DAG.isConstantFPBuildVectorOrConstantFP(N01) &&
!DAG.isConstantFPBuildVectorOrConstantFP(N00)) {
SDValue MulConsts = DAG.getNode(ISD::FMUL, DL, VT, N01, N1);
return DAG.getNode(ISD::FMUL, DL, VT, N00, MulConsts);
}
}
// Match a special-case: we convert X * 2.0 into fadd.
// fmul (fadd X, X), C -> fmul X, 2.0 * C
if (N0.getOpcode() == ISD::FADD && N0.hasOneUse() &&
N0.getOperand(0) == N0.getOperand(1)) {
const SDValue Two = DAG.getConstantFP(2.0, DL, VT);
SDValue MulConsts = DAG.getNode(ISD::FMUL, DL, VT, Two, N1);
return DAG.getNode(ISD::FMUL, DL, VT, N0.getOperand(0), MulConsts);
}
}
// fold (fmul X, 2.0) -> (fadd X, X)
if (N1CFP && N1CFP->isExactlyValue(+2.0))
return DAG.getNode(ISD::FADD, DL, VT, N0, N0);
// fold (fmul X, -1.0) -> (fsub -0.0, X)
if (N1CFP && N1CFP->isExactlyValue(-1.0)) {
if (!LegalOperations || TLI.isOperationLegal(ISD::FSUB, VT)) {
return DAG.getNode(ISD::FSUB, DL, VT,
DAG.getConstantFP(-0.0, DL, VT), N0, Flags);
}
}
// -N0 * -N1 --> N0 * N1
TargetLowering::NegatibleCost CostN0 =
TargetLowering::NegatibleCost::Expensive;
TargetLowering::NegatibleCost CostN1 =
TargetLowering::NegatibleCost::Expensive;
SDValue NegN0 =
TLI.getNegatedExpression(N0, DAG, LegalOperations, ForCodeSize, CostN0);
SDValue NegN1 =
TLI.getNegatedExpression(N1, DAG, LegalOperations, ForCodeSize, CostN1);
if (NegN0 && NegN1 &&
(CostN0 == TargetLowering::NegatibleCost::Cheaper ||
CostN1 == TargetLowering::NegatibleCost::Cheaper))
return DAG.getNode(ISD::FMUL, DL, VT, NegN0, NegN1);
// fold (fmul X, (select (fcmp X > 0.0), -1.0, 1.0)) -> (fneg (fabs X))
// fold (fmul X, (select (fcmp X > 0.0), 1.0, -1.0)) -> (fabs X)
if (Flags.hasNoNaNs() && Flags.hasNoSignedZeros() &&
(N0.getOpcode() == ISD::SELECT || N1.getOpcode() == ISD::SELECT) &&
TLI.isOperationLegal(ISD::FABS, VT)) {
SDValue Select = N0, X = N1;
if (Select.getOpcode() != ISD::SELECT)
std::swap(Select, X);
SDValue Cond = Select.getOperand(0);
auto TrueOpnd = dyn_cast<ConstantFPSDNode>(Select.getOperand(1));
auto FalseOpnd = dyn_cast<ConstantFPSDNode>(Select.getOperand(2));
if (TrueOpnd && FalseOpnd &&
Cond.getOpcode() == ISD::SETCC && Cond.getOperand(0) == X &&
isa<ConstantFPSDNode>(Cond.getOperand(1)) &&
cast<ConstantFPSDNode>(Cond.getOperand(1))->isExactlyValue(0.0)) {
ISD::CondCode CC = cast<CondCodeSDNode>(Cond.getOperand(2))->get();
switch (CC) {
default: break;
case ISD::SETOLT:
case ISD::SETULT:
case ISD::SETOLE:
case ISD::SETULE:
case ISD::SETLT:
case ISD::SETLE:
std::swap(TrueOpnd, FalseOpnd);
LLVM_FALLTHROUGH;
case ISD::SETOGT:
case ISD::SETUGT:
case ISD::SETOGE:
case ISD::SETUGE:
case ISD::SETGT:
case ISD::SETGE:
if (TrueOpnd->isExactlyValue(-1.0) && FalseOpnd->isExactlyValue(1.0) &&
TLI.isOperationLegal(ISD::FNEG, VT))
return DAG.getNode(ISD::FNEG, DL, VT,
DAG.getNode(ISD::FABS, DL, VT, X));
if (TrueOpnd->isExactlyValue(1.0) && FalseOpnd->isExactlyValue(-1.0))
return DAG.getNode(ISD::FABS, DL, VT, X);
break;
}
}
}
// FMUL -> FMA combines:
if (SDValue Fused = visitFMULForFMADistributiveCombine(N)) {
AddToWorklist(Fused.getNode());
return Fused;
}
return SDValue();
}
SDValue DAGCombiner::visitFMA(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1);
EVT VT = N->getValueType(0);
SDLoc DL(N);
const TargetOptions &Options = DAG.getTarget().Options;
// FMA nodes have flags that propagate to the created nodes.
SelectionDAG::FlagInserter FlagsInserter(DAG, N);
bool UnsafeFPMath =
Options.UnsafeFPMath || N->getFlags().hasAllowReassociation();
// Constant fold FMA.
if (isa<ConstantFPSDNode>(N0) &&
isa<ConstantFPSDNode>(N1) &&
isa<ConstantFPSDNode>(N2)) {
return DAG.getNode(ISD::FMA, DL, VT, N0, N1, N2);
}
// (-N0 * -N1) + N2 --> (N0 * N1) + N2
TargetLowering::NegatibleCost CostN0 =
TargetLowering::NegatibleCost::Expensive;
TargetLowering::NegatibleCost CostN1 =
TargetLowering::NegatibleCost::Expensive;
SDValue NegN0 =
TLI.getNegatedExpression(N0, DAG, LegalOperations, ForCodeSize, CostN0);
SDValue NegN1 =
TLI.getNegatedExpression(N1, DAG, LegalOperations, ForCodeSize, CostN1);
if (NegN0 && NegN1 &&
(CostN0 == TargetLowering::NegatibleCost::Cheaper ||
CostN1 == TargetLowering::NegatibleCost::Cheaper))
return DAG.getNode(ISD::FMA, DL, VT, NegN0, NegN1, N2);
if (UnsafeFPMath) {
if (N0CFP && N0CFP->isZero())
return N2;
if (N1CFP && N1CFP->isZero())
return N2;
}
if (N0CFP && N0CFP->isExactlyValue(1.0))
return DAG.getNode(ISD::FADD, SDLoc(N), VT, N1, N2);
if (N1CFP && N1CFP->isExactlyValue(1.0))
return DAG.getNode(ISD::FADD, SDLoc(N), VT, N0, N2);
// Canonicalize (fma c, x, y) -> (fma x, c, y)
if (DAG.isConstantFPBuildVectorOrConstantFP(N0) &&
!DAG.isConstantFPBuildVectorOrConstantFP(N1))
return DAG.getNode(ISD::FMA, SDLoc(N), VT, N1, N0, N2);
if (UnsafeFPMath) {
// (fma x, c1, (fmul x, c2)) -> (fmul x, c1+c2)
if (N2.getOpcode() == ISD::FMUL && N0 == N2.getOperand(0) &&
DAG.isConstantFPBuildVectorOrConstantFP(N1) &&
DAG.isConstantFPBuildVectorOrConstantFP(N2.getOperand(1))) {
return DAG.getNode(ISD::FMUL, DL, VT, N0,
DAG.getNode(ISD::FADD, DL, VT, N1, N2.getOperand(1)));
}
// (fma (fmul x, c1), c2, y) -> (fma x, c1*c2, y)
if (N0.getOpcode() == ISD::FMUL &&
DAG.isConstantFPBuildVectorOrConstantFP(N1) &&
DAG.isConstantFPBuildVectorOrConstantFP(N0.getOperand(1))) {
return DAG.getNode(ISD::FMA, DL, VT, N0.getOperand(0),
DAG.getNode(ISD::FMUL, DL, VT, N1, N0.getOperand(1)),
N2);
}
}
// (fma x, -1, y) -> (fadd (fneg x), y)
if (N1CFP) {
if (N1CFP->isExactlyValue(1.0))
return DAG.getNode(ISD::FADD, DL, VT, N0, N2);
if (N1CFP->isExactlyValue(-1.0) &&
(!LegalOperations || TLI.isOperationLegal(ISD::FNEG, VT))) {
SDValue RHSNeg = DAG.getNode(ISD::FNEG, DL, VT, N0);
AddToWorklist(RHSNeg.getNode());
return DAG.getNode(ISD::FADD, DL, VT, N2, RHSNeg);
}
// fma (fneg x), K, y -> fma x -K, y
if (N0.getOpcode() == ISD::FNEG &&
(TLI.isOperationLegal(ISD::ConstantFP, VT) ||
(N1.hasOneUse() && !TLI.isFPImmLegal(N1CFP->getValueAPF(), VT,
ForCodeSize)))) {
return DAG.getNode(ISD::FMA, DL, VT, N0.getOperand(0),
DAG.getNode(ISD::FNEG, DL, VT, N1), N2);
}
}
if (UnsafeFPMath) {
// (fma x, c, x) -> (fmul x, (c+1))
if (N1CFP && N0 == N2) {
return DAG.getNode(
ISD::FMUL, DL, VT, N0,
DAG.getNode(ISD::FADD, DL, VT, N1, DAG.getConstantFP(1.0, DL, VT)));
}
// (fma x, c, (fneg x)) -> (fmul x, (c-1))
if (N1CFP && N2.getOpcode() == ISD::FNEG && N2.getOperand(0) == N0) {
return DAG.getNode(
ISD::FMUL, DL, VT, N0,
DAG.getNode(ISD::FADD, DL, VT, N1, DAG.getConstantFP(-1.0, DL, VT)));
}
}
// fold ((fma (fneg X), Y, (fneg Z)) -> fneg (fma X, Y, Z))
// fold ((fma X, (fneg Y), (fneg Z)) -> fneg (fma X, Y, Z))
if (!TLI.isFNegFree(VT))
if (SDValue Neg = TLI.getCheaperNegatedExpression(
SDValue(N, 0), DAG, LegalOperations, ForCodeSize))
return DAG.getNode(ISD::FNEG, DL, VT, Neg);
return SDValue();
}
// Combine multiple FDIVs with the same divisor into multiple FMULs by the
// reciprocal.
// E.g., (a / D; b / D;) -> (recip = 1.0 / D; a * recip; b * recip)
// Notice that this is not always beneficial. One reason is different targets
// may have different costs for FDIV and FMUL, so sometimes the cost of two
// FDIVs may be lower than the cost of one FDIV and two FMULs. Another reason
// is the critical path is increased from "one FDIV" to "one FDIV + one FMUL".
SDValue DAGCombiner::combineRepeatedFPDivisors(SDNode *N) {
// TODO: Limit this transform based on optsize/minsize - it always creates at
// least 1 extra instruction. But the perf win may be substantial enough
// that only minsize should restrict this.
bool UnsafeMath = DAG.getTarget().Options.UnsafeFPMath;
const SDNodeFlags Flags = N->getFlags();
if (LegalDAG || (!UnsafeMath && !Flags.hasAllowReciprocal()))
return SDValue();
// Skip if current node is a reciprocal/fneg-reciprocal.
SDValue N0 = N->getOperand(0), N1 = N->getOperand(1);
ConstantFPSDNode *N0CFP = isConstOrConstSplatFP(N0, /* AllowUndefs */ true);
if (N0CFP && (N0CFP->isExactlyValue(1.0) || N0CFP->isExactlyValue(-1.0)))
return SDValue();
// Exit early if the target does not want this transform or if there can't
// possibly be enough uses of the divisor to make the transform worthwhile.
unsigned MinUses = TLI.combineRepeatedFPDivisors();
// For splat vectors, scale the number of uses by the splat factor. If we can
// convert the division into a scalar op, that will likely be much faster.
unsigned NumElts = 1;
EVT VT = N->getValueType(0);
if (VT.isVector() && DAG.isSplatValue(N1))
NumElts = VT.getVectorMinNumElements();
if (!MinUses || (N1->use_size() * NumElts) < MinUses)
return SDValue();
// Find all FDIV users of the same divisor.
// Use a set because duplicates may be present in the user list.
SetVector<SDNode *> Users;
for (auto *U : N1->uses()) {
if (U->getOpcode() == ISD::FDIV && U->getOperand(1) == N1) {
// Skip X/sqrt(X) that has not been simplified to sqrt(X) yet.
if (U->getOperand(1).getOpcode() == ISD::FSQRT &&
U->getOperand(0) == U->getOperand(1).getOperand(0) &&
U->getFlags().hasAllowReassociation() &&
U->getFlags().hasNoSignedZeros())
continue;
// This division is eligible for optimization only if global unsafe math
// is enabled or if this division allows reciprocal formation.
if (UnsafeMath || U->getFlags().hasAllowReciprocal())
Users.insert(U);
}
}
// Now that we have the actual number of divisor uses, make sure it meets
// the minimum threshold specified by the target.
if ((Users.size() * NumElts) < MinUses)
return SDValue();
SDLoc DL(N);
SDValue FPOne = DAG.getConstantFP(1.0, DL, VT);
SDValue Reciprocal = DAG.getNode(ISD::FDIV, DL, VT, FPOne, N1, Flags);
// Dividend / Divisor -> Dividend * Reciprocal
for (auto *U : Users) {
SDValue Dividend = U->getOperand(0);
if (Dividend != FPOne) {
SDValue NewNode = DAG.getNode(ISD::FMUL, SDLoc(U), VT, Dividend,
Reciprocal, Flags);
CombineTo(U, NewNode);
} else if (U != Reciprocal.getNode()) {
// In the absence of fast-math-flags, this user node is always the
// same node as Reciprocal, but with FMF they may be different nodes.
CombineTo(U, Reciprocal);
}
}
return SDValue(N, 0); // N was replaced.
}
SDValue DAGCombiner::visitFDIV(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
SDLoc DL(N);
const TargetOptions &Options = DAG.getTarget().Options;
SDNodeFlags Flags = N->getFlags();
SelectionDAG::FlagInserter FlagsInserter(DAG, N);
if (SDValue R = DAG.simplifyFPBinop(N->getOpcode(), N0, N1, Flags))
return R;
// fold (fdiv c1, c2) -> c1/c2
if (SDValue C = DAG.FoldConstantArithmetic(ISD::FDIV, DL, VT, {N0, N1}))
return C;
// fold vector ops
if (VT.isVector())
if (SDValue FoldedVOp = SimplifyVBinOp(N, DL))
return FoldedVOp;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
if (SDValue V = combineRepeatedFPDivisors(N))
return V;
if (Options.UnsafeFPMath || Flags.hasAllowReciprocal()) {
// fold (fdiv X, c2) -> fmul X, 1/c2 if losing precision is acceptable.
if (auto *N1CFP = dyn_cast<ConstantFPSDNode>(N1)) {
// Compute the reciprocal 1.0 / c2.
const APFloat &N1APF = N1CFP->getValueAPF();
APFloat Recip(N1APF.getSemantics(), 1); // 1.0
APFloat::opStatus st = Recip.divide(N1APF, APFloat::rmNearestTiesToEven);
// Only do the transform if the reciprocal is a legal fp immediate that
// isn't too nasty (eg NaN, denormal, ...).
if ((st == APFloat::opOK || st == APFloat::opInexact) && // Not too nasty
(!LegalOperations ||
// FIXME: custom lowering of ConstantFP might fail (see e.g. ARM
// backend)... we should handle this gracefully after Legalize.
// TLI.isOperationLegalOrCustom(ISD::ConstantFP, VT) ||
TLI.isOperationLegal(ISD::ConstantFP, VT) ||
TLI.isFPImmLegal(Recip, VT, ForCodeSize)))
return DAG.getNode(ISD::FMUL, DL, VT, N0,
DAG.getConstantFP(Recip, DL, VT));
}
// If this FDIV is part of a reciprocal square root, it may be folded
// into a target-specific square root estimate instruction.
if (N1.getOpcode() == ISD::FSQRT) {
if (SDValue RV = buildRsqrtEstimate(N1.getOperand(0), Flags))
return DAG.getNode(ISD::FMUL, DL, VT, N0, RV);
} else if (N1.getOpcode() == ISD::FP_EXTEND &&
N1.getOperand(0).getOpcode() == ISD::FSQRT) {
if (SDValue RV =
buildRsqrtEstimate(N1.getOperand(0).getOperand(0), Flags)) {
RV = DAG.getNode(ISD::FP_EXTEND, SDLoc(N1), VT, RV);
AddToWorklist(RV.getNode());
return DAG.getNode(ISD::FMUL, DL, VT, N0, RV);
}
} else if (N1.getOpcode() == ISD::FP_ROUND &&
N1.getOperand(0).getOpcode() == ISD::FSQRT) {
if (SDValue RV =
buildRsqrtEstimate(N1.getOperand(0).getOperand(0), Flags)) {
RV = DAG.getNode(ISD::FP_ROUND, SDLoc(N1), VT, RV, N1.getOperand(1));
AddToWorklist(RV.getNode());
return DAG.getNode(ISD::FMUL, DL, VT, N0, RV);
}
} else if (N1.getOpcode() == ISD::FMUL) {
// Look through an FMUL. Even though this won't remove the FDIV directly,
// it's still worthwhile to get rid of the FSQRT if possible.
SDValue Sqrt, Y;
if (N1.getOperand(0).getOpcode() == ISD::FSQRT) {
Sqrt = N1.getOperand(0);
Y = N1.getOperand(1);
} else if (N1.getOperand(1).getOpcode() == ISD::FSQRT) {
Sqrt = N1.getOperand(1);
Y = N1.getOperand(0);
}
if (Sqrt.getNode()) {
// If the other multiply operand is known positive, pull it into the
// sqrt. That will eliminate the division if we convert to an estimate.
if (Flags.hasAllowReassociation() && N1.hasOneUse() &&
N1->getFlags().hasAllowReassociation() && Sqrt.hasOneUse()) {
SDValue A;
if (Y.getOpcode() == ISD::FABS && Y.hasOneUse())
A = Y.getOperand(0);
else if (Y == Sqrt.getOperand(0))
A = Y;
if (A) {
// X / (fabs(A) * sqrt(Z)) --> X / sqrt(A*A*Z) --> X * rsqrt(A*A*Z)
// X / (A * sqrt(A)) --> X / sqrt(A*A*A) --> X * rsqrt(A*A*A)
SDValue AA = DAG.getNode(ISD::FMUL, DL, VT, A, A);
SDValue AAZ =
DAG.getNode(ISD::FMUL, DL, VT, AA, Sqrt.getOperand(0));
if (SDValue Rsqrt = buildRsqrtEstimate(AAZ, Flags))
return DAG.getNode(ISD::FMUL, DL, VT, N0, Rsqrt);
// Estimate creation failed. Clean up speculatively created nodes.
recursivelyDeleteUnusedNodes(AAZ.getNode());
}
}
// We found a FSQRT, so try to make this fold:
// X / (Y * sqrt(Z)) -> X * (rsqrt(Z) / Y)
if (SDValue Rsqrt = buildRsqrtEstimate(Sqrt.getOperand(0), Flags)) {
SDValue Div = DAG.getNode(ISD::FDIV, SDLoc(N1), VT, Rsqrt, Y);
AddToWorklist(Div.getNode());
return DAG.getNode(ISD::FMUL, DL, VT, N0, Div);
}
}
}
// Fold into a reciprocal estimate and multiply instead of a real divide.
if (Options.NoInfsFPMath || Flags.hasNoInfs())
if (SDValue RV = BuildDivEstimate(N0, N1, Flags))
return RV;
}
// Fold X/Sqrt(X) -> Sqrt(X)
if ((Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros()) &&
(Options.UnsafeFPMath || Flags.hasAllowReassociation()))
if (N1.getOpcode() == ISD::FSQRT && N0 == N1.getOperand(0))
return N1;
// (fdiv (fneg X), (fneg Y)) -> (fdiv X, Y)
TargetLowering::NegatibleCost CostN0 =
TargetLowering::NegatibleCost::Expensive;
TargetLowering::NegatibleCost CostN1 =
TargetLowering::NegatibleCost::Expensive;
SDValue NegN0 =
TLI.getNegatedExpression(N0, DAG, LegalOperations, ForCodeSize, CostN0);
SDValue NegN1 =
TLI.getNegatedExpression(N1, DAG, LegalOperations, ForCodeSize, CostN1);
if (NegN0 && NegN1 &&
(CostN0 == TargetLowering::NegatibleCost::Cheaper ||
CostN1 == TargetLowering::NegatibleCost::Cheaper))
return DAG.getNode(ISD::FDIV, SDLoc(N), VT, NegN0, NegN1);
return SDValue();
}
SDValue DAGCombiner::visitFREM(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
SDNodeFlags Flags = N->getFlags();
SelectionDAG::FlagInserter FlagsInserter(DAG, N);
if (SDValue R = DAG.simplifyFPBinop(N->getOpcode(), N0, N1, Flags))
return R;
// fold (frem c1, c2) -> fmod(c1,c2)
if (SDValue C = DAG.FoldConstantArithmetic(ISD::FREM, SDLoc(N), VT, {N0, N1}))
return C;
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
return SDValue();
}
SDValue DAGCombiner::visitFSQRT(SDNode *N) {
SDNodeFlags Flags = N->getFlags();
const TargetOptions &Options = DAG.getTarget().Options;
// Require 'ninf' flag since sqrt(+Inf) = +Inf, but the estimation goes as:
// sqrt(+Inf) == rsqrt(+Inf) * +Inf = 0 * +Inf = NaN
if (!Flags.hasApproximateFuncs() ||
(!Options.NoInfsFPMath && !Flags.hasNoInfs()))
return SDValue();
SDValue N0 = N->getOperand(0);
if (TLI.isFsqrtCheap(N0, DAG))
return SDValue();
// FSQRT nodes have flags that propagate to the created nodes.
// TODO: If this is N0/sqrt(N0), and we reach this node before trying to
// transform the fdiv, we may produce a sub-optimal estimate sequence
// because the reciprocal calculation may not have to filter out a
// 0.0 input.
return buildSqrtEstimate(N0, Flags);
}
/// copysign(x, fp_extend(y)) -> copysign(x, y)
/// copysign(x, fp_round(y)) -> copysign(x, y)
static inline bool CanCombineFCOPYSIGN_EXTEND_ROUND(SDNode *N) {
SDValue N1 = N->getOperand(1);
if ((N1.getOpcode() == ISD::FP_EXTEND ||
N1.getOpcode() == ISD::FP_ROUND)) {
EVT N1VT = N1->getValueType(0);
EVT N1Op0VT = N1->getOperand(0).getValueType();
// Always fold no-op FP casts.
if (N1VT == N1Op0VT)
return true;
// Do not optimize out type conversion of f128 type yet.
// For some targets like x86_64, configuration is changed to keep one f128
// value in one SSE register, but instruction selection cannot handle
// FCOPYSIGN on SSE registers yet.
if (N1Op0VT == MVT::f128)
return false;
// Avoid mismatched vector operand types, for better instruction selection.
if (N1Op0VT.isVector())
return false;
return true;
}
return false;
}
SDValue DAGCombiner::visitFCOPYSIGN(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
// fold (fcopysign c1, c2) -> fcopysign(c1,c2)
if (SDValue C =
DAG.FoldConstantArithmetic(ISD::FCOPYSIGN, SDLoc(N), VT, {N0, N1}))
return C;
if (ConstantFPSDNode *N1C = isConstOrConstSplatFP(N->getOperand(1))) {
const APFloat &V = N1C->getValueAPF();
// copysign(x, c1) -> fabs(x) iff ispos(c1)
// copysign(x, c1) -> fneg(fabs(x)) iff isneg(c1)
if (!V.isNegative()) {
if (!LegalOperations || TLI.isOperationLegal(ISD::FABS, VT))
return DAG.getNode(ISD::FABS, SDLoc(N), VT, N0);
} else {
if (!LegalOperations || TLI.isOperationLegal(ISD::FNEG, VT))
return DAG.getNode(ISD::FNEG, SDLoc(N), VT,
DAG.getNode(ISD::FABS, SDLoc(N0), VT, N0));
}
}
// copysign(fabs(x), y) -> copysign(x, y)
// copysign(fneg(x), y) -> copysign(x, y)
// copysign(copysign(x,z), y) -> copysign(x, y)
if (N0.getOpcode() == ISD::FABS || N0.getOpcode() == ISD::FNEG ||
N0.getOpcode() == ISD::FCOPYSIGN)
return DAG.getNode(ISD::FCOPYSIGN, SDLoc(N), VT, N0.getOperand(0), N1);
// copysign(x, abs(y)) -> abs(x)
if (N1.getOpcode() == ISD::FABS)
return DAG.getNode(ISD::FABS, SDLoc(N), VT, N0);
// copysign(x, copysign(y,z)) -> copysign(x, z)
if (N1.getOpcode() == ISD::FCOPYSIGN)
return DAG.getNode(ISD::FCOPYSIGN, SDLoc(N), VT, N0, N1.getOperand(1));
// copysign(x, fp_extend(y)) -> copysign(x, y)
// copysign(x, fp_round(y)) -> copysign(x, y)
if (CanCombineFCOPYSIGN_EXTEND_ROUND(N))
return DAG.getNode(ISD::FCOPYSIGN, SDLoc(N), VT, N0, N1.getOperand(0));
return SDValue();
}
SDValue DAGCombiner::visitFPOW(SDNode *N) {
ConstantFPSDNode *ExponentC = isConstOrConstSplatFP(N->getOperand(1));
if (!ExponentC)
return SDValue();
SelectionDAG::FlagInserter FlagsInserter(DAG, N);
// Try to convert x ** (1/3) into cube root.
// TODO: Handle the various flavors of long double.
// TODO: Since we're approximating, we don't need an exact 1/3 exponent.
// Some range near 1/3 should be fine.
EVT VT = N->getValueType(0);
if ((VT == MVT::f32 && ExponentC->getValueAPF().isExactlyValue(1.0f/3.0f)) ||
(VT == MVT::f64 && ExponentC->getValueAPF().isExactlyValue(1.0/3.0))) {
// pow(-0.0, 1/3) = +0.0; cbrt(-0.0) = -0.0.
// pow(-inf, 1/3) = +inf; cbrt(-inf) = -inf.
// pow(-val, 1/3) = nan; cbrt(-val) = -num.
// For regular numbers, rounding may cause the results to differ.
// Therefore, we require { nsz ninf nnan afn } for this transform.
// TODO: We could select out the special cases if we don't have nsz/ninf.
SDNodeFlags Flags = N->getFlags();
if (!Flags.hasNoSignedZeros() || !Flags.hasNoInfs() || !Flags.hasNoNaNs() ||
!Flags.hasApproximateFuncs())
return SDValue();
// Do not create a cbrt() libcall if the target does not have it, and do not
// turn a pow that has lowering support into a cbrt() libcall.
if (!DAG.getLibInfo().has(LibFunc_cbrt) ||
(!DAG.getTargetLoweringInfo().isOperationExpand(ISD::FPOW, VT) &&
DAG.getTargetLoweringInfo().isOperationExpand(ISD::FCBRT, VT)))
return SDValue();
return DAG.getNode(ISD::FCBRT, SDLoc(N), VT, N->getOperand(0));
}
// Try to convert x ** (1/4) and x ** (3/4) into square roots.
// x ** (1/2) is canonicalized to sqrt, so we do not bother with that case.
// TODO: This could be extended (using a target hook) to handle smaller
// power-of-2 fractional exponents.
bool ExponentIs025 = ExponentC->getValueAPF().isExactlyValue(0.25);
bool ExponentIs075 = ExponentC->getValueAPF().isExactlyValue(0.75);
if (ExponentIs025 || ExponentIs075) {
// pow(-0.0, 0.25) = +0.0; sqrt(sqrt(-0.0)) = -0.0.
// pow(-inf, 0.25) = +inf; sqrt(sqrt(-inf)) = NaN.
// pow(-0.0, 0.75) = +0.0; sqrt(-0.0) * sqrt(sqrt(-0.0)) = +0.0.
// pow(-inf, 0.75) = +inf; sqrt(-inf) * sqrt(sqrt(-inf)) = NaN.
// For regular numbers, rounding may cause the results to differ.
// Therefore, we require { nsz ninf afn } for this transform.
// TODO: We could select out the special cases if we don't have nsz/ninf.
SDNodeFlags Flags = N->getFlags();
// We only need no signed zeros for the 0.25 case.
if ((!Flags.hasNoSignedZeros() && ExponentIs025) || !Flags.hasNoInfs() ||
!Flags.hasApproximateFuncs())
return SDValue();
// Don't double the number of libcalls. We are trying to inline fast code.
if (!DAG.getTargetLoweringInfo().isOperationLegalOrCustom(ISD::FSQRT, VT))
return SDValue();
// Assume that libcalls are the smallest code.
// TODO: This restriction should probably be lifted for vectors.
if (ForCodeSize)
return SDValue();
// pow(X, 0.25) --> sqrt(sqrt(X))
SDLoc DL(N);
SDValue Sqrt = DAG.getNode(ISD::FSQRT, DL, VT, N->getOperand(0));
SDValue SqrtSqrt = DAG.getNode(ISD::FSQRT, DL, VT, Sqrt);
if (ExponentIs025)
return SqrtSqrt;
// pow(X, 0.75) --> sqrt(X) * sqrt(sqrt(X))
return DAG.getNode(ISD::FMUL, DL, VT, Sqrt, SqrtSqrt);
}
return SDValue();
}
static SDValue foldFPToIntToFP(SDNode *N, SelectionDAG &DAG,
const TargetLowering &TLI) {
// We only do this if the target has legal ftrunc. Otherwise, we'd likely be
// replacing casts with a libcall. We also must be allowed to ignore -0.0
// because FTRUNC will return -0.0 for (-1.0, -0.0), but using integer
// conversions would return +0.0.
// FIXME: We should be able to use node-level FMF here.
// TODO: If strict math, should we use FABS (+ range check for signed cast)?
EVT VT = N->getValueType(0);
if (!TLI.isOperationLegal(ISD::FTRUNC, VT) ||
!DAG.getTarget().Options.NoSignedZerosFPMath)
return SDValue();
// fptosi/fptoui round towards zero, so converting from FP to integer and
// back is the same as an 'ftrunc': [us]itofp (fpto[us]i X) --> ftrunc X
SDValue N0 = N->getOperand(0);
if (N->getOpcode() == ISD::SINT_TO_FP && N0.getOpcode() == ISD::FP_TO_SINT &&
N0.getOperand(0).getValueType() == VT)
return DAG.getNode(ISD::FTRUNC, SDLoc(N), VT, N0.getOperand(0));
if (N->getOpcode() == ISD::UINT_TO_FP && N0.getOpcode() == ISD::FP_TO_UINT &&
N0.getOperand(0).getValueType() == VT)
return DAG.getNode(ISD::FTRUNC, SDLoc(N), VT, N0.getOperand(0));
return SDValue();
}
SDValue DAGCombiner::visitSINT_TO_FP(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
EVT OpVT = N0.getValueType();
// [us]itofp(undef) = 0, because the result value is bounded.
if (N0.isUndef())
return DAG.getConstantFP(0.0, SDLoc(N), VT);
// fold (sint_to_fp c1) -> c1fp
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
// ...but only if the target supports immediate floating-point values
(!LegalOperations ||
TLI.isOperationLegalOrCustom(ISD::ConstantFP, VT)))
return DAG.getNode(ISD::SINT_TO_FP, SDLoc(N), VT, N0);
// If the input is a legal type, and SINT_TO_FP is not legal on this target,
// but UINT_TO_FP is legal on this target, try to convert.
if (!hasOperation(ISD::SINT_TO_FP, OpVT) &&
hasOperation(ISD::UINT_TO_FP, OpVT)) {
// If the sign bit is known to be zero, we can change this to UINT_TO_FP.
if (DAG.SignBitIsZero(N0))
return DAG.getNode(ISD::UINT_TO_FP, SDLoc(N), VT, N0);
}
// The next optimizations are desirable only if SELECT_CC can be lowered.
// fold (sint_to_fp (setcc x, y, cc)) -> (select (setcc x, y, cc), -1.0, 0.0)
if (N0.getOpcode() == ISD::SETCC && N0.getValueType() == MVT::i1 &&
!VT.isVector() &&
(!LegalOperations || TLI.isOperationLegalOrCustom(ISD::ConstantFP, VT))) {
SDLoc DL(N);
return DAG.getSelect(DL, VT, N0, DAG.getConstantFP(-1.0, DL, VT),
DAG.getConstantFP(0.0, DL, VT));
}
// fold (sint_to_fp (zext (setcc x, y, cc))) ->
// (select (setcc x, y, cc), 1.0, 0.0)
if (N0.getOpcode() == ISD::ZERO_EXTEND &&
N0.getOperand(0).getOpcode() == ISD::SETCC && !VT.isVector() &&
(!LegalOperations || TLI.isOperationLegalOrCustom(ISD::ConstantFP, VT))) {
SDLoc DL(N);
return DAG.getSelect(DL, VT, N0.getOperand(0),
DAG.getConstantFP(1.0, DL, VT),
DAG.getConstantFP(0.0, DL, VT));
}
if (SDValue FTrunc = foldFPToIntToFP(N, DAG, TLI))
return FTrunc;
return SDValue();
}
SDValue DAGCombiner::visitUINT_TO_FP(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
EVT OpVT = N0.getValueType();
// [us]itofp(undef) = 0, because the result value is bounded.
if (N0.isUndef())
return DAG.getConstantFP(0.0, SDLoc(N), VT);
// fold (uint_to_fp c1) -> c1fp
if (DAG.isConstantIntBuildVectorOrConstantInt(N0) &&
// ...but only if the target supports immediate floating-point values
(!LegalOperations ||
TLI.isOperationLegalOrCustom(ISD::ConstantFP, VT)))
return DAG.getNode(ISD::UINT_TO_FP, SDLoc(N), VT, N0);
// If the input is a legal type, and UINT_TO_FP is not legal on this target,
// but SINT_TO_FP is legal on this target, try to convert.
if (!hasOperation(ISD::UINT_TO_FP, OpVT) &&
hasOperation(ISD::SINT_TO_FP, OpVT)) {
// If the sign bit is known to be zero, we can change this to SINT_TO_FP.
if (DAG.SignBitIsZero(N0))
return DAG.getNode(ISD::SINT_TO_FP, SDLoc(N), VT, N0);
}
// fold (uint_to_fp (setcc x, y, cc)) -> (select (setcc x, y, cc), 1.0, 0.0)
if (N0.getOpcode() == ISD::SETCC && !VT.isVector() &&
(!LegalOperations || TLI.isOperationLegalOrCustom(ISD::ConstantFP, VT))) {
SDLoc DL(N);
return DAG.getSelect(DL, VT, N0, DAG.getConstantFP(1.0, DL, VT),
DAG.getConstantFP(0.0, DL, VT));
}
if (SDValue FTrunc = foldFPToIntToFP(N, DAG, TLI))
return FTrunc;
return SDValue();
}
// Fold (fp_to_{s/u}int ({s/u}int_to_fpx)) -> zext x, sext x, trunc x, or x
static SDValue FoldIntToFPToInt(SDNode *N, SelectionDAG &DAG) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
if (N0.getOpcode() != ISD::UINT_TO_FP && N0.getOpcode() != ISD::SINT_TO_FP)
return SDValue();
SDValue Src = N0.getOperand(0);
EVT SrcVT = Src.getValueType();
bool IsInputSigned = N0.getOpcode() == ISD::SINT_TO_FP;
bool IsOutputSigned = N->getOpcode() == ISD::FP_TO_SINT;
// We can safely assume the conversion won't overflow the output range,
// because (for example) (uint8_t)18293.f is undefined behavior.
// Since we can assume the conversion won't overflow, our decision as to
// whether the input will fit in the float should depend on the minimum
// of the input range and output range.
// This means this is also safe for a signed input and unsigned output, since
// a negative input would lead to undefined behavior.
unsigned InputSize = (int)SrcVT.getScalarSizeInBits() - IsInputSigned;
unsigned OutputSize = (int)VT.getScalarSizeInBits();
unsigned ActualSize = std::min(InputSize, OutputSize);
const fltSemantics &sem = DAG.EVTToAPFloatSemantics(N0.getValueType());
// We can only fold away the float conversion if the input range can be
// represented exactly in the float range.
if (APFloat::semanticsPrecision(sem) >= ActualSize) {
if (VT.getScalarSizeInBits() > SrcVT.getScalarSizeInBits()) {
unsigned ExtOp = IsInputSigned && IsOutputSigned ? ISD::SIGN_EXTEND
: ISD::ZERO_EXTEND;
return DAG.getNode(ExtOp, SDLoc(N), VT, Src);
}
if (VT.getScalarSizeInBits() < SrcVT.getScalarSizeInBits())
return DAG.getNode(ISD::TRUNCATE, SDLoc(N), VT, Src);
return DAG.getBitcast(VT, Src);
}
return SDValue();
}
SDValue DAGCombiner::visitFP_TO_SINT(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (fp_to_sint undef) -> undef
if (N0.isUndef())
return DAG.getUNDEF(VT);
// fold (fp_to_sint c1fp) -> c1
if (DAG.isConstantFPBuildVectorOrConstantFP(N0))
return DAG.getNode(ISD::FP_TO_SINT, SDLoc(N), VT, N0);
return FoldIntToFPToInt(N, DAG);
}
SDValue DAGCombiner::visitFP_TO_UINT(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (fp_to_uint undef) -> undef
if (N0.isUndef())
return DAG.getUNDEF(VT);
// fold (fp_to_uint c1fp) -> c1
if (DAG.isConstantFPBuildVectorOrConstantFP(N0))
return DAG.getNode(ISD::FP_TO_UINT, SDLoc(N), VT, N0);
return FoldIntToFPToInt(N, DAG);
}
SDValue DAGCombiner::visitFP_ROUND(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
EVT VT = N->getValueType(0);
// fold (fp_round c1fp) -> c1fp
if (N0CFP)
return DAG.getNode(ISD::FP_ROUND, SDLoc(N), VT, N0, N1);
// fold (fp_round (fp_extend x)) -> x
if (N0.getOpcode() == ISD::FP_EXTEND && VT == N0.getOperand(0).getValueType())
return N0.getOperand(0);
// fold (fp_round (fp_round x)) -> (fp_round x)
if (N0.getOpcode() == ISD::FP_ROUND) {
const bool NIsTrunc = N->getConstantOperandVal(1) == 1;
const bool N0IsTrunc = N0.getConstantOperandVal(1) == 1;
// Skip this folding if it results in an fp_round from f80 to f16.
//
// f80 to f16 always generates an expensive (and as yet, unimplemented)
// libcall to __truncxfhf2 instead of selecting native f16 conversion
// instructions from f32 or f64. Moreover, the first (value-preserving)
// fp_round from f80 to either f32 or f64 may become a NOP in platforms like
// x86.
if (N0.getOperand(0).getValueType() == MVT::f80 && VT == MVT::f16)
return SDValue();
// If the first fp_round isn't a value preserving truncation, it might
// introduce a tie in the second fp_round, that wouldn't occur in the
// single-step fp_round we want to fold to.
// In other words, double rounding isn't the same as rounding.
// Also, this is a value preserving truncation iff both fp_round's are.
if (DAG.getTarget().Options.UnsafeFPMath || N0IsTrunc) {
SDLoc DL(N);
return DAG.getNode(ISD::FP_ROUND, DL, VT, N0.getOperand(0),
DAG.getIntPtrConstant(NIsTrunc && N0IsTrunc, DL));
}
}
// fold (fp_round (copysign X, Y)) -> (copysign (fp_round X), Y)
if (N0.getOpcode() == ISD::FCOPYSIGN && N0->hasOneUse()) {
SDValue Tmp = DAG.getNode(ISD::FP_ROUND, SDLoc(N0), VT,
N0.getOperand(0), N1);
AddToWorklist(Tmp.getNode());
return DAG.getNode(ISD::FCOPYSIGN, SDLoc(N), VT,
Tmp, N0.getOperand(1));
}
if (SDValue NewVSel = matchVSelectOpSizesWithSetCC(N))
return NewVSel;
return SDValue();
}
SDValue DAGCombiner::visitFP_EXTEND(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// If this is fp_round(fpextend), don't fold it, allow ourselves to be folded.
if (N->hasOneUse() &&
N->use_begin()->getOpcode() == ISD::FP_ROUND)
return SDValue();
// fold (fp_extend c1fp) -> c1fp
if (DAG.isConstantFPBuildVectorOrConstantFP(N0))
return DAG.getNode(ISD::FP_EXTEND, SDLoc(N), VT, N0);
// fold (fp_extend (fp16_to_fp op)) -> (fp16_to_fp op)
if (N0.getOpcode() == ISD::FP16_TO_FP &&
TLI.getOperationAction(ISD::FP16_TO_FP, VT) == TargetLowering::Legal)
return DAG.getNode(ISD::FP16_TO_FP, SDLoc(N), VT, N0.getOperand(0));
// Turn fp_extend(fp_round(X, 1)) -> x since the fp_round doesn't affect the
// value of X.
if (N0.getOpcode() == ISD::FP_ROUND
&& N0.getConstantOperandVal(1) == 1) {
SDValue In = N0.getOperand(0);
if (In.getValueType() == VT) return In;
if (VT.bitsLT(In.getValueType()))
return DAG.getNode(ISD::FP_ROUND, SDLoc(N), VT,
In, N0.getOperand(1));
return DAG.getNode(ISD::FP_EXTEND, SDLoc(N), VT, In);
}
// fold (fpext (load x)) -> (fpext (fptrunc (extload x)))
if (ISD::isNormalLoad(N0.getNode()) && N0.hasOneUse() &&
TLI.isLoadExtLegalOrCustom(ISD::EXTLOAD, VT, N0.getValueType())) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
SDValue ExtLoad = DAG.getExtLoad(ISD::EXTLOAD, SDLoc(N), VT,
LN0->getChain(),
LN0->getBasePtr(), N0.getValueType(),
LN0->getMemOperand());
CombineTo(N, ExtLoad);
CombineTo(N0.getNode(),
DAG.getNode(ISD::FP_ROUND, SDLoc(N0),
N0.getValueType(), ExtLoad,
DAG.getIntPtrConstant(1, SDLoc(N0))),
ExtLoad.getValue(1));
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
if (SDValue NewVSel = matchVSelectOpSizesWithSetCC(N))
return NewVSel;
return SDValue();
}
SDValue DAGCombiner::visitFCEIL(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (fceil c1) -> fceil(c1)
if (DAG.isConstantFPBuildVectorOrConstantFP(N0))
return DAG.getNode(ISD::FCEIL, SDLoc(N), VT, N0);
return SDValue();
}
SDValue DAGCombiner::visitFTRUNC(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (ftrunc c1) -> ftrunc(c1)
if (DAG.isConstantFPBuildVectorOrConstantFP(N0))
return DAG.getNode(ISD::FTRUNC, SDLoc(N), VT, N0);
// fold ftrunc (known rounded int x) -> x
// ftrunc is a part of fptosi/fptoui expansion on some targets, so this is
// likely to be generated to extract integer from a rounded floating value.
switch (N0.getOpcode()) {
default: break;
case ISD::FRINT:
case ISD::FTRUNC:
case ISD::FNEARBYINT:
case ISD::FFLOOR:
case ISD::FCEIL:
return N0;
}
return SDValue();
}
SDValue DAGCombiner::visitFFLOOR(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (ffloor c1) -> ffloor(c1)
if (DAG.isConstantFPBuildVectorOrConstantFP(N0))
return DAG.getNode(ISD::FFLOOR, SDLoc(N), VT, N0);
return SDValue();
}
SDValue DAGCombiner::visitFNEG(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
SelectionDAG::FlagInserter FlagsInserter(DAG, N);
// Constant fold FNEG.
if (DAG.isConstantFPBuildVectorOrConstantFP(N0))
return DAG.getNode(ISD::FNEG, SDLoc(N), VT, N0);
if (SDValue NegN0 =
TLI.getNegatedExpression(N0, DAG, LegalOperations, ForCodeSize))
return NegN0;
// -(X-Y) -> (Y-X) is unsafe because when X==Y, -0.0 != +0.0
// FIXME: This is duplicated in getNegatibleCost, but getNegatibleCost doesn't
// know it was called from a context with a nsz flag if the input fsub does
// not.
if (N0.getOpcode() == ISD::FSUB &&
(DAG.getTarget().Options.NoSignedZerosFPMath ||
N->getFlags().hasNoSignedZeros()) && N0.hasOneUse()) {
return DAG.getNode(ISD::FSUB, SDLoc(N), VT, N0.getOperand(1),
N0.getOperand(0));
}
if (SDValue Cast = foldSignChangeInBitcast(N))
return Cast;
return SDValue();
}
SDValue DAGCombiner::visitFMinMax(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
EVT VT = N->getValueType(0);
const SDNodeFlags Flags = N->getFlags();
unsigned Opc = N->getOpcode();
bool PropagatesNaN = Opc == ISD::FMINIMUM || Opc == ISD::FMAXIMUM;
bool IsMin = Opc == ISD::FMINNUM || Opc == ISD::FMINIMUM;
SelectionDAG::FlagInserter FlagsInserter(DAG, N);
// Constant fold.
if (SDValue C = DAG.FoldConstantArithmetic(Opc, SDLoc(N), VT, {N0, N1}))
return C;
// Canonicalize to constant on RHS.
if (DAG.isConstantFPBuildVectorOrConstantFP(N0) &&
!DAG.isConstantFPBuildVectorOrConstantFP(N1))
return DAG.getNode(N->getOpcode(), SDLoc(N), VT, N1, N0);
if (const ConstantFPSDNode *N1CFP = isConstOrConstSplatFP(N1)) {
const APFloat &AF = N1CFP->getValueAPF();
// minnum(X, nan) -> X
// maxnum(X, nan) -> X
// minimum(X, nan) -> nan
// maximum(X, nan) -> nan
if (AF.isNaN())
return PropagatesNaN ? N->getOperand(1) : N->getOperand(0);
// In the following folds, inf can be replaced with the largest finite
// float, if the ninf flag is set.
if (AF.isInfinity() || (Flags.hasNoInfs() && AF.isLargest())) {
// minnum(X, -inf) -> -inf
// maxnum(X, +inf) -> +inf
// minimum(X, -inf) -> -inf if nnan
// maximum(X, +inf) -> +inf if nnan
if (IsMin == AF.isNegative() && (!PropagatesNaN || Flags.hasNoNaNs()))
return N->getOperand(1);
// minnum(X, +inf) -> X if nnan
// maxnum(X, -inf) -> X if nnan
// minimum(X, +inf) -> X
// maximum(X, -inf) -> X
if (IsMin != AF.isNegative() && (PropagatesNaN || Flags.hasNoNaNs()))
return N->getOperand(0);
}
}
return SDValue();
}
SDValue DAGCombiner::visitFABS(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
// fold (fabs c1) -> fabs(c1)
if (DAG.isConstantFPBuildVectorOrConstantFP(N0))
return DAG.getNode(ISD::FABS, SDLoc(N), VT, N0);
// fold (fabs (fabs x)) -> (fabs x)
if (N0.getOpcode() == ISD::FABS)
return N->getOperand(0);
// fold (fabs (fneg x)) -> (fabs x)
// fold (fabs (fcopysign x, y)) -> (fabs x)
if (N0.getOpcode() == ISD::FNEG || N0.getOpcode() == ISD::FCOPYSIGN)
return DAG.getNode(ISD::FABS, SDLoc(N), VT, N0.getOperand(0));
if (SDValue Cast = foldSignChangeInBitcast(N))
return Cast;
return SDValue();
}
SDValue DAGCombiner::visitBRCOND(SDNode *N) {
SDValue Chain = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
// BRCOND(FREEZE(cond)) is equivalent to BRCOND(cond) (both are
// nondeterministic jumps).
if (N1->getOpcode() == ISD::FREEZE && N1.hasOneUse()) {
return DAG.getNode(ISD::BRCOND, SDLoc(N), MVT::Other, Chain,
N1->getOperand(0), N2);
}
// If N is a constant we could fold this into a fallthrough or unconditional
// branch. However that doesn't happen very often in normal code, because
// Instcombine/SimplifyCFG should have handled the available opportunities.
// If we did this folding here, it would be necessary to update the
// MachineBasicBlock CFG, which is awkward.
// fold a brcond with a setcc condition into a BR_CC node if BR_CC is legal
// on the target.
if (N1.getOpcode() == ISD::SETCC &&
TLI.isOperationLegalOrCustom(ISD::BR_CC,
N1.getOperand(0).getValueType())) {
return DAG.getNode(ISD::BR_CC, SDLoc(N), MVT::Other,
Chain, N1.getOperand(2),
N1.getOperand(0), N1.getOperand(1), N2);
}
if (N1.hasOneUse()) {
// rebuildSetCC calls visitXor which may change the Chain when there is a
// STRICT_FSETCC/STRICT_FSETCCS involved. Use a handle to track changes.
HandleSDNode ChainHandle(Chain);
if (SDValue NewN1 = rebuildSetCC(N1))
return DAG.getNode(ISD::BRCOND, SDLoc(N), MVT::Other,
ChainHandle.getValue(), NewN1, N2);
}
return SDValue();
}
SDValue DAGCombiner::rebuildSetCC(SDValue N) {
if (N.getOpcode() == ISD::SRL ||
(N.getOpcode() == ISD::TRUNCATE &&
(N.getOperand(0).hasOneUse() &&
N.getOperand(0).getOpcode() == ISD::SRL))) {
// Look pass the truncate.
if (N.getOpcode() == ISD::TRUNCATE)
N = N.getOperand(0);
// Match this pattern so that we can generate simpler code:
//
// %a = ...
// %b = and i32 %a, 2
// %c = srl i32 %b, 1
// brcond i32 %c ...
//
// into
//
// %a = ...
// %b = and i32 %a, 2
// %c = setcc eq %b, 0
// brcond %c ...
//
// This applies only when the AND constant value has one bit set and the
// SRL constant is equal to the log2 of the AND constant. The back-end is
// smart enough to convert the result into a TEST/JMP sequence.
SDValue Op0 = N.getOperand(0);
SDValue Op1 = N.getOperand(1);
if (Op0.getOpcode() == ISD::AND && Op1.getOpcode() == ISD::Constant) {
SDValue AndOp1 = Op0.getOperand(1);
if (AndOp1.getOpcode() == ISD::Constant) {
const APInt &AndConst = cast<ConstantSDNode>(AndOp1)->getAPIntValue();
if (AndConst.isPowerOf2() &&
cast<ConstantSDNode>(Op1)->getAPIntValue() == AndConst.logBase2()) {
SDLoc DL(N);
return DAG.getSetCC(DL, getSetCCResultType(Op0.getValueType()),
Op0, DAG.getConstant(0, DL, Op0.getValueType()),
ISD::SETNE);
}
}
}
}
// Transform (brcond (xor x, y)) -> (brcond (setcc, x, y, ne))
// Transform (brcond (xor (xor x, y), -1)) -> (brcond (setcc, x, y, eq))
if (N.getOpcode() == ISD::XOR) {
// Because we may call this on a speculatively constructed
// SimplifiedSetCC Node, we need to simplify this node first.
// Ideally this should be folded into SimplifySetCC and not
// here. For now, grab a handle to N so we don't lose it from
// replacements interal to the visit.
HandleSDNode XORHandle(N);
while (N.getOpcode() == ISD::XOR) {
SDValue Tmp = visitXOR(N.getNode());
// No simplification done.
if (!Tmp.getNode())
break;
// Returning N is form in-visit replacement that may invalidated
// N. Grab value from Handle.
if (Tmp.getNode() == N.getNode())
N = XORHandle.getValue();
else // Node simplified. Try simplifying again.
N = Tmp;
}
if (N.getOpcode() != ISD::XOR)
return N;
SDValue Op0 = N->getOperand(0);
SDValue Op1 = N->getOperand(1);
if (Op0.getOpcode() != ISD::SETCC && Op1.getOpcode() != ISD::SETCC) {
bool Equal = false;
// (brcond (xor (xor x, y), -1)) -> (brcond (setcc x, y, eq))
if (isBitwiseNot(N) && Op0.hasOneUse() && Op0.getOpcode() == ISD::XOR &&
Op0.getValueType() == MVT::i1) {
N = Op0;
Op0 = N->getOperand(0);
Op1 = N->getOperand(1);
Equal = true;
}
EVT SetCCVT = N.getValueType();
if (LegalTypes)
SetCCVT = getSetCCResultType(SetCCVT);
// Replace the uses of XOR with SETCC
return DAG.getSetCC(SDLoc(N), SetCCVT, Op0, Op1,
Equal ? ISD::SETEQ : ISD::SETNE);
}
}
return SDValue();
}
// Operand List for BR_CC: Chain, CondCC, CondLHS, CondRHS, DestBB.
//
SDValue DAGCombiner::visitBR_CC(SDNode *N) {
CondCodeSDNode *CC = cast<CondCodeSDNode>(N->getOperand(1));
SDValue CondLHS = N->getOperand(2), CondRHS = N->getOperand(3);
// If N is a constant we could fold this into a fallthrough or unconditional
// branch. However that doesn't happen very often in normal code, because
// Instcombine/SimplifyCFG should have handled the available opportunities.
// If we did this folding here, it would be necessary to update the
// MachineBasicBlock CFG, which is awkward.
// Use SimplifySetCC to simplify SETCC's.
SDValue Simp = SimplifySetCC(getSetCCResultType(CondLHS.getValueType()),
CondLHS, CondRHS, CC->get(), SDLoc(N),
false);
if (Simp.getNode()) AddToWorklist(Simp.getNode());
// fold to a simpler setcc
if (Simp.getNode() && Simp.getOpcode() == ISD::SETCC)
return DAG.getNode(ISD::BR_CC, SDLoc(N), MVT::Other,
N->getOperand(0), Simp.getOperand(2),
Simp.getOperand(0), Simp.getOperand(1),
N->getOperand(4));
return SDValue();
}
static bool getCombineLoadStoreParts(SDNode *N, unsigned Inc, unsigned Dec,
bool &IsLoad, bool &IsMasked, SDValue &Ptr,
const TargetLowering &TLI) {
if (LoadSDNode *LD = dyn_cast<LoadSDNode>(N)) {
if (LD->isIndexed())
return false;
EVT VT = LD->getMemoryVT();
if (!TLI.isIndexedLoadLegal(Inc, VT) && !TLI.isIndexedLoadLegal(Dec, VT))
return false;
Ptr = LD->getBasePtr();
} else if (StoreSDNode *ST = dyn_cast<StoreSDNode>(N)) {
if (ST->isIndexed())
return false;
EVT VT = ST->getMemoryVT();
if (!TLI.isIndexedStoreLegal(Inc, VT) && !TLI.isIndexedStoreLegal(Dec, VT))
return false;
Ptr = ST->getBasePtr();
IsLoad = false;
} else if (MaskedLoadSDNode *LD = dyn_cast<MaskedLoadSDNode>(N)) {
if (LD->isIndexed())
return false;
EVT VT = LD->getMemoryVT();
if (!TLI.isIndexedMaskedLoadLegal(Inc, VT) &&
!TLI.isIndexedMaskedLoadLegal(Dec, VT))
return false;
Ptr = LD->getBasePtr();
IsMasked = true;
} else if (MaskedStoreSDNode *ST = dyn_cast<MaskedStoreSDNode>(N)) {
if (ST->isIndexed())
return false;
EVT VT = ST->getMemoryVT();
if (!TLI.isIndexedMaskedStoreLegal(Inc, VT) &&
!TLI.isIndexedMaskedStoreLegal(Dec, VT))
return false;
Ptr = ST->getBasePtr();
IsLoad = false;
IsMasked = true;
} else {
return false;
}
return true;
}
/// Try turning a load/store into a pre-indexed load/store when the base
/// pointer is an add or subtract and it has other uses besides the load/store.
/// After the transformation, the new indexed load/store has effectively folded
/// the add/subtract in and all of its other uses are redirected to the
/// new load/store.
bool DAGCombiner::CombineToPreIndexedLoadStore(SDNode *N) {
if (Level < AfterLegalizeDAG)
return false;
bool IsLoad = true;
bool IsMasked = false;
SDValue Ptr;
if (!getCombineLoadStoreParts(N, ISD::PRE_INC, ISD::PRE_DEC, IsLoad, IsMasked,
Ptr, TLI))
return false;
// If the pointer is not an add/sub, or if it doesn't have multiple uses, bail
// out. There is no reason to make this a preinc/predec.
if ((Ptr.getOpcode() != ISD::ADD && Ptr.getOpcode() != ISD::SUB) ||
Ptr->hasOneUse())
return false;
// Ask the target to do addressing mode selection.
SDValue BasePtr;
SDValue Offset;
ISD::MemIndexedMode AM = ISD::UNINDEXED;
if (!TLI.getPreIndexedAddressParts(N, BasePtr, Offset, AM, DAG))
return false;
// Backends without true r+i pre-indexed forms may need to pass a
// constant base with a variable offset so that constant coercion
// will work with the patterns in canonical form.
bool Swapped = false;
if (isa<ConstantSDNode>(BasePtr)) {
std::swap(BasePtr, Offset);
Swapped = true;
}
// Don't create a indexed load / store with zero offset.
if (isNullConstant(Offset))
return false;
// Try turning it into a pre-indexed load / store except when:
// 1) The new base ptr is a frame index.
// 2) If N is a store and the new base ptr is either the same as or is a
// predecessor of the value being stored.
// 3) Another use of old base ptr is a predecessor of N. If ptr is folded
// that would create a cycle.
// 4) All uses are load / store ops that use it as old base ptr.
// Check #1. Preinc'ing a frame index would require copying the stack pointer
// (plus the implicit offset) to a register to preinc anyway.
if (isa<FrameIndexSDNode>(BasePtr) || isa<RegisterSDNode>(BasePtr))
return false;
// Check #2.
if (!IsLoad) {
SDValue Val = IsMasked ? cast<MaskedStoreSDNode>(N)->getValue()
: cast<StoreSDNode>(N)->getValue();
// Would require a copy.
if (Val == BasePtr)
return false;
// Would create a cycle.
if (Val == Ptr || Ptr->isPredecessorOf(Val.getNode()))
return false;
}
// Caches for hasPredecessorHelper.
SmallPtrSet<const SDNode *, 32> Visited;
SmallVector<const SDNode *, 16> Worklist;
Worklist.push_back(N);
// If the offset is a constant, there may be other adds of constants that
// can be folded with this one. We should do this to avoid having to keep
// a copy of the original base pointer.
SmallVector<SDNode *, 16> OtherUses;
if (isa<ConstantSDNode>(Offset))
for (SDNode::use_iterator UI = BasePtr->use_begin(),
UE = BasePtr->use_end();
UI != UE; ++UI) {
SDUse &Use = UI.getUse();
// Skip the use that is Ptr and uses of other results from BasePtr's
// node (important for nodes that return multiple results).
if (Use.getUser() == Ptr.getNode() || Use != BasePtr)
continue;
if (SDNode::hasPredecessorHelper(Use.getUser(), Visited, Worklist))
continue;
if (Use.getUser()->getOpcode() != ISD::ADD &&
Use.getUser()->getOpcode() != ISD::SUB) {
OtherUses.clear();
break;
}
SDValue Op1 = Use.getUser()->getOperand((UI.getOperandNo() + 1) & 1);
if (!isa<ConstantSDNode>(Op1)) {
OtherUses.clear();
break;
}
// FIXME: In some cases, we can be smarter about this.
if (Op1.getValueType() != Offset.getValueType()) {
OtherUses.clear();
break;
}
OtherUses.push_back(Use.getUser());
}
if (Swapped)
std::swap(BasePtr, Offset);
// Now check for #3 and #4.
bool RealUse = false;
for (SDNode *Use : Ptr->uses()) {
if (Use == N)
continue;
if (SDNode::hasPredecessorHelper(Use, Visited, Worklist))
return false;
// If Ptr may be folded in addressing mode of other use, then it's
// not profitable to do this transformation.
if (!canFoldInAddressingMode(Ptr.getNode(), Use, DAG, TLI))
RealUse = true;
}
if (!RealUse)
return false;
SDValue Result;
if (!IsMasked) {
if (IsLoad)
Result = DAG.getIndexedLoad(SDValue(N, 0), SDLoc(N), BasePtr, Offset, AM);
else
Result =
DAG.getIndexedStore(SDValue(N, 0), SDLoc(N), BasePtr, Offset, AM);
} else {
if (IsLoad)
Result = DAG.getIndexedMaskedLoad(SDValue(N, 0), SDLoc(N), BasePtr,
Offset, AM);
else
Result = DAG.getIndexedMaskedStore(SDValue(N, 0), SDLoc(N), BasePtr,
Offset, AM);
}
++PreIndexedNodes;
++NodesCombined;
LLVM_DEBUG(dbgs() << "\nReplacing.4 "; N->dump(&DAG); dbgs() << "\nWith: ";
Result.dump(&DAG); dbgs() << '\n');
WorklistRemover DeadNodes(*this);
if (IsLoad) {
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result.getValue(0));
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), Result.getValue(2));
} else {
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result.getValue(1));
}
// Finally, since the node is now dead, remove it from the graph.
deleteAndRecombine(N);
if (Swapped)
std::swap(BasePtr, Offset);
// Replace other uses of BasePtr that can be updated to use Ptr
for (unsigned i = 0, e = OtherUses.size(); i != e; ++i) {
unsigned OffsetIdx = 1;
if (OtherUses[i]->getOperand(OffsetIdx).getNode() == BasePtr.getNode())
OffsetIdx = 0;
assert(OtherUses[i]->getOperand(!OffsetIdx).getNode() ==
BasePtr.getNode() && "Expected BasePtr operand");
// We need to replace ptr0 in the following expression:
// x0 * offset0 + y0 * ptr0 = t0
// knowing that
// x1 * offset1 + y1 * ptr0 = t1 (the indexed load/store)
//
// where x0, x1, y0 and y1 in {-1, 1} are given by the types of the
// indexed load/store and the expression that needs to be re-written.
//
// Therefore, we have:
// t0 = (x0 * offset0 - x1 * y0 * y1 *offset1) + (y0 * y1) * t1
auto *CN = cast<ConstantSDNode>(OtherUses[i]->getOperand(OffsetIdx));
const APInt &Offset0 = CN->getAPIntValue();
const APInt &Offset1 = cast<ConstantSDNode>(Offset)->getAPIntValue();
int X0 = (OtherUses[i]->getOpcode() == ISD::SUB && OffsetIdx == 1) ? -1 : 1;
int Y0 = (OtherUses[i]->getOpcode() == ISD::SUB && OffsetIdx == 0) ? -1 : 1;
int X1 = (AM == ISD::PRE_DEC && !Swapped) ? -1 : 1;
int Y1 = (AM == ISD::PRE_DEC && Swapped) ? -1 : 1;
unsigned Opcode = (Y0 * Y1 < 0) ? ISD::SUB : ISD::ADD;
APInt CNV = Offset0;
if (X0 < 0) CNV = -CNV;
if (X1 * Y0 * Y1 < 0) CNV = CNV + Offset1;
else CNV = CNV - Offset1;
SDLoc DL(OtherUses[i]);
// We can now generate the new expression.
SDValue NewOp1 = DAG.getConstant(CNV, DL, CN->getValueType(0));
SDValue NewOp2 = Result.getValue(IsLoad ? 1 : 0);
SDValue NewUse = DAG.getNode(Opcode,
DL,
OtherUses[i]->getValueType(0), NewOp1, NewOp2);
DAG.ReplaceAllUsesOfValueWith(SDValue(OtherUses[i], 0), NewUse);
deleteAndRecombine(OtherUses[i]);
}
// Replace the uses of Ptr with uses of the updated base value.
DAG.ReplaceAllUsesOfValueWith(Ptr, Result.getValue(IsLoad ? 1 : 0));
deleteAndRecombine(Ptr.getNode());
AddToWorklist(Result.getNode());
return true;
}
static bool shouldCombineToPostInc(SDNode *N, SDValue Ptr, SDNode *PtrUse,
SDValue &BasePtr, SDValue &Offset,
ISD::MemIndexedMode &AM,
SelectionDAG &DAG,
const TargetLowering &TLI) {
if (PtrUse == N ||
(PtrUse->getOpcode() != ISD::ADD && PtrUse->getOpcode() != ISD::SUB))
return false;
if (!TLI.getPostIndexedAddressParts(N, PtrUse, BasePtr, Offset, AM, DAG))
return false;
// Don't create a indexed load / store with zero offset.
if (isNullConstant(Offset))
return false;
if (isa<FrameIndexSDNode>(BasePtr) || isa<RegisterSDNode>(BasePtr))
return false;
SmallPtrSet<const SDNode *, 32> Visited;
for (SDNode *Use : BasePtr->uses()) {
if (Use == Ptr.getNode())
continue;
// No if there's a later user which could perform the index instead.
if (isa<MemSDNode>(Use)) {
bool IsLoad = true;
bool IsMasked = false;
SDValue OtherPtr;
if (getCombineLoadStoreParts(Use, ISD::POST_INC, ISD::POST_DEC, IsLoad,
IsMasked, OtherPtr, TLI)) {
SmallVector<const SDNode *, 2> Worklist;
Worklist.push_back(Use);
if (SDNode::hasPredecessorHelper(N, Visited, Worklist))
return false;
}
}
// If all the uses are load / store addresses, then don't do the
// transformation.
if (Use->getOpcode() == ISD::ADD || Use->getOpcode() == ISD::SUB) {
for (SDNode *UseUse : Use->uses())
if (canFoldInAddressingMode(Use, UseUse, DAG, TLI))
return false;
}
}
return true;
}
static SDNode *getPostIndexedLoadStoreOp(SDNode *N, bool &IsLoad,
bool &IsMasked, SDValue &Ptr,
SDValue &BasePtr, SDValue &Offset,
ISD::MemIndexedMode &AM,
SelectionDAG &DAG,
const TargetLowering &TLI) {
if (!getCombineLoadStoreParts(N, ISD::POST_INC, ISD::POST_DEC, IsLoad,
IsMasked, Ptr, TLI) ||
Ptr->hasOneUse())
return nullptr;
// Try turning it into a post-indexed load / store except when
// 1) All uses are load / store ops that use it as base ptr (and
// it may be folded as addressing mmode).
// 2) Op must be independent of N, i.e. Op is neither a predecessor
// nor a successor of N. Otherwise, if Op is folded that would
// create a cycle.
for (SDNode *Op : Ptr->uses()) {
// Check for #1.
if (!shouldCombineToPostInc(N, Ptr, Op, BasePtr, Offset, AM, DAG, TLI))
continue;
// Check for #2.
SmallPtrSet<const SDNode *, 32> Visited;
SmallVector<const SDNode *, 8> Worklist;
// Ptr is predecessor to both N and Op.
Visited.insert(Ptr.getNode());
Worklist.push_back(N);
Worklist.push_back(Op);
if (!SDNode::hasPredecessorHelper(N, Visited, Worklist) &&
!SDNode::hasPredecessorHelper(Op, Visited, Worklist))
return Op;
}
return nullptr;
}
/// Try to combine a load/store with a add/sub of the base pointer node into a
/// post-indexed load/store. The transformation folded the add/subtract into the
/// new indexed load/store effectively and all of its uses are redirected to the
/// new load/store.
bool DAGCombiner::CombineToPostIndexedLoadStore(SDNode *N) {
if (Level < AfterLegalizeDAG)
return false;
bool IsLoad = true;
bool IsMasked = false;
SDValue Ptr;
SDValue BasePtr;
SDValue Offset;
ISD::MemIndexedMode AM = ISD::UNINDEXED;
SDNode *Op = getPostIndexedLoadStoreOp(N, IsLoad, IsMasked, Ptr, BasePtr,
Offset, AM, DAG, TLI);
if (!Op)
return false;
SDValue Result;
if (!IsMasked)
Result = IsLoad ? DAG.getIndexedLoad(SDValue(N, 0), SDLoc(N), BasePtr,
Offset, AM)
: DAG.getIndexedStore(SDValue(N, 0), SDLoc(N),
BasePtr, Offset, AM);
else
Result = IsLoad ? DAG.getIndexedMaskedLoad(SDValue(N, 0), SDLoc(N),
BasePtr, Offset, AM)
: DAG.getIndexedMaskedStore(SDValue(N, 0), SDLoc(N),
BasePtr, Offset, AM);
++PostIndexedNodes;
++NodesCombined;
LLVM_DEBUG(dbgs() << "\nReplacing.5 "; N->dump(&DAG); dbgs() << "\nWith: ";
Result.dump(&DAG); dbgs() << '\n');
WorklistRemover DeadNodes(*this);
if (IsLoad) {
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result.getValue(0));
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), Result.getValue(2));
} else {
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result.getValue(1));
}
// Finally, since the node is now dead, remove it from the graph.
deleteAndRecombine(N);
// Replace the uses of Use with uses of the updated base value.
DAG.ReplaceAllUsesOfValueWith(SDValue(Op, 0),
Result.getValue(IsLoad ? 1 : 0));
deleteAndRecombine(Op);
return true;
}
/// Return the base-pointer arithmetic from an indexed \p LD.
SDValue DAGCombiner::SplitIndexingFromLoad(LoadSDNode *LD) {
ISD::MemIndexedMode AM = LD->getAddressingMode();
assert(AM != ISD::UNINDEXED);
SDValue BP = LD->getOperand(1);
SDValue Inc = LD->getOperand(2);
// Some backends use TargetConstants for load offsets, but don't expect
// TargetConstants in general ADD nodes. We can convert these constants into
// regular Constants (if the constant is not opaque).
assert((Inc.getOpcode() != ISD::TargetConstant ||
!cast<ConstantSDNode>(Inc)->isOpaque()) &&
"Cannot split out indexing using opaque target constants");
if (Inc.getOpcode() == ISD::TargetConstant) {
ConstantSDNode *ConstInc = cast<ConstantSDNode>(Inc);
Inc = DAG.getConstant(*ConstInc->getConstantIntValue(), SDLoc(Inc),
ConstInc->getValueType(0));
}
unsigned Opc =
(AM == ISD::PRE_INC || AM == ISD::POST_INC ? ISD::ADD : ISD::SUB);
return DAG.getNode(Opc, SDLoc(LD), BP.getSimpleValueType(), BP, Inc);
}
static inline ElementCount numVectorEltsOrZero(EVT T) {
return T.isVector() ? T.getVectorElementCount() : ElementCount::getFixed(0);
}
bool DAGCombiner::getTruncatedStoreValue(StoreSDNode *ST, SDValue &Val) {
Val = ST->getValue();
EVT STType = Val.getValueType();
EVT STMemType = ST->getMemoryVT();
if (STType == STMemType)
return true;
if (isTypeLegal(STMemType))
return false; // fail.
if (STType.isFloatingPoint() && STMemType.isFloatingPoint() &&
TLI.isOperationLegal(ISD::FTRUNC, STMemType)) {
Val = DAG.getNode(ISD::FTRUNC, SDLoc(ST), STMemType, Val);
return true;
}
if (numVectorEltsOrZero(STType) == numVectorEltsOrZero(STMemType) &&
STType.isInteger() && STMemType.isInteger()) {
Val = DAG.getNode(ISD::TRUNCATE, SDLoc(ST), STMemType, Val);
return true;
}
if (STType.getSizeInBits() == STMemType.getSizeInBits()) {
Val = DAG.getBitcast(STMemType, Val);
return true;
}
return false; // fail.
}
bool DAGCombiner::extendLoadedValueToExtension(LoadSDNode *LD, SDValue &Val) {
EVT LDMemType = LD->getMemoryVT();
EVT LDType = LD->getValueType(0);
assert(Val.getValueType() == LDMemType &&
"Attempting to extend value of non-matching type");
if (LDType == LDMemType)
return true;
if (LDMemType.isInteger() && LDType.isInteger()) {
switch (LD->getExtensionType()) {
case ISD::NON_EXTLOAD:
Val = DAG.getBitcast(LDType, Val);
return true;
case ISD::EXTLOAD:
Val = DAG.getNode(ISD::ANY_EXTEND, SDLoc(LD), LDType, Val);
return true;
case ISD::SEXTLOAD:
Val = DAG.getNode(ISD::SIGN_EXTEND, SDLoc(LD), LDType, Val);
return true;
case ISD::ZEXTLOAD:
Val = DAG.getNode(ISD::ZERO_EXTEND, SDLoc(LD), LDType, Val);
return true;
}
}
return false;
}
SDValue DAGCombiner::ForwardStoreValueToDirectLoad(LoadSDNode *LD) {
if (OptLevel == CodeGenOpt::None || !LD->isSimple())
return SDValue();
SDValue Chain = LD->getOperand(0);
StoreSDNode *ST = dyn_cast<StoreSDNode>(Chain.getNode());
// TODO: Relax this restriction for unordered atomics (see D66309)
if (!ST || !ST->isSimple())
return SDValue();
EVT LDType = LD->getValueType(0);
EVT LDMemType = LD->getMemoryVT();
EVT STMemType = ST->getMemoryVT();
EVT STType = ST->getValue().getValueType();
// There are two cases to consider here:
// 1. The store is fixed width and the load is scalable. In this case we
// don't know at compile time if the store completely envelops the load
// so we abandon the optimisation.
// 2. The store is scalable and the load is fixed width. We could
// potentially support a limited number of cases here, but there has been
// no cost-benefit analysis to prove it's worth it.
bool LdStScalable = LDMemType.isScalableVector();
if (LdStScalable != STMemType.isScalableVector())
return SDValue();
// If we are dealing with scalable vectors on a big endian platform the
// calculation of offsets below becomes trickier, since we do not know at
// compile time the absolute size of the vector. Until we've done more
// analysis on big-endian platforms it seems better to bail out for now.
if (LdStScalable && DAG.getDataLayout().isBigEndian())
return SDValue();
BaseIndexOffset BasePtrLD = BaseIndexOffset::match(LD, DAG);
BaseIndexOffset BasePtrST = BaseIndexOffset::match(ST, DAG);
int64_t Offset;
if (!BasePtrST.equalBaseIndex(BasePtrLD, DAG, Offset))
return SDValue();
// Normalize for Endianness. After this Offset=0 will denote that the least
// significant bit in the loaded value maps to the least significant bit in
// the stored value). With Offset=n (for n > 0) the loaded value starts at the
// n:th least significant byte of the stored value.
if (DAG.getDataLayout().isBigEndian())
Offset = ((int64_t)STMemType.getStoreSizeInBits().getFixedSize() -
(int64_t)LDMemType.getStoreSizeInBits().getFixedSize()) /
8 -
Offset;
// Check that the stored value cover all bits that are loaded.
bool STCoversLD;
TypeSize LdMemSize = LDMemType.getSizeInBits();
TypeSize StMemSize = STMemType.getSizeInBits();
if (LdStScalable)
STCoversLD = (Offset == 0) && LdMemSize == StMemSize;
else
STCoversLD = (Offset >= 0) && (Offset * 8 + LdMemSize.getFixedSize() <=
StMemSize.getFixedSize());
auto ReplaceLd = [&](LoadSDNode *LD, SDValue Val, SDValue Chain) -> SDValue {
if (LD->isIndexed()) {
// Cannot handle opaque target constants and we must respect the user's
// request not to split indexes from loads.
if (!canSplitIdx(LD))
return SDValue();
SDValue Idx = SplitIndexingFromLoad(LD);
SDValue Ops[] = {Val, Idx, Chain};
return CombineTo(LD, Ops, 3);
}
return CombineTo(LD, Val, Chain);
};
if (!STCoversLD)
return SDValue();
// Memory as copy space (potentially masked).
if (Offset == 0 && LDType == STType && STMemType == LDMemType) {
// Simple case: Direct non-truncating forwarding
if (LDType.getSizeInBits() == LdMemSize)
return ReplaceLd(LD, ST->getValue(), Chain);
// Can we model the truncate and extension with an and mask?
if (STType.isInteger() && LDMemType.isInteger() && !STType.isVector() &&
!LDMemType.isVector() && LD->getExtensionType() != ISD::SEXTLOAD) {
// Mask to size of LDMemType
auto Mask =
DAG.getConstant(APInt::getLowBitsSet(STType.getFixedSizeInBits(),
StMemSize.getFixedSize()),
SDLoc(ST), STType);
auto Val = DAG.getNode(ISD::AND, SDLoc(LD), LDType, ST->getValue(), Mask);
return ReplaceLd(LD, Val, Chain);
}
}
// TODO: Deal with nonzero offset.
if (LD->getBasePtr().isUndef() || Offset != 0)
return SDValue();
// Model necessary truncations / extenstions.
SDValue Val;
// Truncate Value To Stored Memory Size.
do {
if (!getTruncatedStoreValue(ST, Val))
continue;
if (!isTypeLegal(LDMemType))
continue;
if (STMemType != LDMemType) {
// TODO: Support vectors? This requires extract_subvector/bitcast.
if (!STMemType.isVector() && !LDMemType.isVector() &&
STMemType.isInteger() && LDMemType.isInteger())
Val = DAG.getNode(ISD::TRUNCATE, SDLoc(LD), LDMemType, Val);
else
continue;
}
if (!extendLoadedValueToExtension(LD, Val))
continue;
return ReplaceLd(LD, Val, Chain);
} while (false);
// On failure, cleanup dead nodes we may have created.
if (Val->use_empty())
deleteAndRecombine(Val.getNode());
return SDValue();
}
SDValue DAGCombiner::visitLOAD(SDNode *N) {
LoadSDNode *LD = cast<LoadSDNode>(N);
SDValue Chain = LD->getChain();
SDValue Ptr = LD->getBasePtr();
// If load is not volatile and there are no uses of the loaded value (and
// the updated indexed value in case of indexed loads), change uses of the
// chain value into uses of the chain input (i.e. delete the dead load).
// TODO: Allow this for unordered atomics (see D66309)
if (LD->isSimple()) {
if (N->getValueType(1) == MVT::Other) {
// Unindexed loads.
if (!N->hasAnyUseOfValue(0)) {
// It's not safe to use the two value CombineTo variant here. e.g.
// v1, chain2 = load chain1, loc
// v2, chain3 = load chain2, loc
// v3 = add v2, c
// Now we replace use of chain2 with chain1. This makes the second load
// isomorphic to the one we are deleting, and thus makes this load live.
LLVM_DEBUG(dbgs() << "\nReplacing.6 "; N->dump(&DAG);
dbgs() << "\nWith chain: "; Chain.dump(&DAG);
dbgs() << "\n");
WorklistRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), Chain);
AddUsersToWorklist(Chain.getNode());
if (N->use_empty())
deleteAndRecombine(N);
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
} else {
// Indexed loads.
assert(N->getValueType(2) == MVT::Other && "Malformed indexed loads?");
// If this load has an opaque TargetConstant offset, then we cannot split
// the indexing into an add/sub directly (that TargetConstant may not be
// valid for a different type of node, and we cannot convert an opaque
// target constant into a regular constant).
bool CanSplitIdx = canSplitIdx(LD);
if (!N->hasAnyUseOfValue(0) && (CanSplitIdx || !N->hasAnyUseOfValue(1))) {
SDValue Undef = DAG.getUNDEF(N->getValueType(0));
SDValue Index;
if (N->hasAnyUseOfValue(1) && CanSplitIdx) {
Index = SplitIndexingFromLoad(LD);
// Try to fold the base pointer arithmetic into subsequent loads and
// stores.
AddUsersToWorklist(N);
} else
Index = DAG.getUNDEF(N->getValueType(1));
LLVM_DEBUG(dbgs() << "\nReplacing.7 "; N->dump(&DAG);
dbgs() << "\nWith: "; Undef.dump(&DAG);
dbgs() << " and 2 other values\n");
WorklistRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Undef);
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), Index);
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 2), Chain);
deleteAndRecombine(N);
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
}
}
// If this load is directly stored, replace the load value with the stored
// value.
if (auto V = ForwardStoreValueToDirectLoad(LD))
return V;
// Try to infer better alignment information than the load already has.
if (OptLevel != CodeGenOpt::None && LD->isUnindexed() && !LD->isAtomic()) {
if (MaybeAlign Alignment = DAG.InferPtrAlign(Ptr)) {
if (*Alignment > LD->getAlign() &&
isAligned(*Alignment, LD->getSrcValueOffset())) {
SDValue NewLoad = DAG.getExtLoad(
LD->getExtensionType(), SDLoc(N), LD->getValueType(0), Chain, Ptr,
LD->getPointerInfo(), LD->getMemoryVT(), *Alignment,
LD->getMemOperand()->getFlags(), LD->getAAInfo());
// NewLoad will always be N as we are only refining the alignment
assert(NewLoad.getNode() == N);
(void)NewLoad;
}
}
}
if (LD->isUnindexed()) {
// Walk up chain skipping non-aliasing memory nodes.
SDValue BetterChain = FindBetterChain(LD, Chain);
// If there is a better chain.
if (Chain != BetterChain) {
SDValue ReplLoad;
// Replace the chain to void dependency.
if (LD->getExtensionType() == ISD::NON_EXTLOAD) {
ReplLoad = DAG.getLoad(N->getValueType(0), SDLoc(LD),
BetterChain, Ptr, LD->getMemOperand());
} else {
ReplLoad = DAG.getExtLoad(LD->getExtensionType(), SDLoc(LD),
LD->getValueType(0),
BetterChain, Ptr, LD->getMemoryVT(),
LD->getMemOperand());
}
// Create token factor to keep old chain connected.
SDValue Token = DAG.getNode(ISD::TokenFactor, SDLoc(N),
MVT::Other, Chain, ReplLoad.getValue(1));
// Replace uses with load result and token factor
return CombineTo(N, ReplLoad.getValue(0), Token);
}
}
// Try transforming N to an indexed load.
if (CombineToPreIndexedLoadStore(N) || CombineToPostIndexedLoadStore(N))
return SDValue(N, 0);
// Try to slice up N to more direct loads if the slices are mapped to
// different register banks or pairing can take place.
if (SliceUpLoad(N))
return SDValue(N, 0);
return SDValue();
}
namespace {
/// Helper structure used to slice a load in smaller loads.
/// Basically a slice is obtained from the following sequence:
/// Origin = load Ty1, Base
/// Shift = srl Ty1 Origin, CstTy Amount
/// Inst = trunc Shift to Ty2
///
/// Then, it will be rewritten into:
/// Slice = load SliceTy, Base + SliceOffset
/// [Inst = zext Slice to Ty2], only if SliceTy <> Ty2
///
/// SliceTy is deduced from the number of bits that are actually used to
/// build Inst.
struct LoadedSlice {
/// Helper structure used to compute the cost of a slice.
struct Cost {
/// Are we optimizing for code size.
bool ForCodeSize = false;
/// Various cost.
unsigned Loads = 0;
unsigned Truncates = 0;
unsigned CrossRegisterBanksCopies = 0;
unsigned ZExts = 0;
unsigned Shift = 0;
explicit Cost(bool ForCodeSize) : ForCodeSize(ForCodeSize) {}
/// Get the cost of one isolated slice.
Cost(const LoadedSlice &LS, bool ForCodeSize)
: ForCodeSize(ForCodeSize), Loads(1) {
EVT TruncType = LS.Inst->getValueType(0);
EVT LoadedType = LS.getLoadedType();
if (TruncType != LoadedType &&
!LS.DAG->getTargetLoweringInfo().isZExtFree(LoadedType, TruncType))
ZExts = 1;
}
/// Account for slicing gain in the current cost.
/// Slicing provide a few gains like removing a shift or a
/// truncate. This method allows to grow the cost of the original
/// load with the gain from this slice.
void addSliceGain(const LoadedSlice &LS) {
// Each slice saves a truncate.
const TargetLowering &TLI = LS.DAG->getTargetLoweringInfo();
if (!TLI.isTruncateFree(LS.Inst->getOperand(0).getValueType(),
LS.Inst->getValueType(0)))
++Truncates;
// If there is a shift amount, this slice gets rid of it.
if (LS.Shift)
++Shift;
// If this slice can merge a cross register bank copy, account for it.
if (LS.canMergeExpensiveCrossRegisterBankCopy())
++CrossRegisterBanksCopies;
}
Cost &operator+=(const Cost &RHS) {
Loads += RHS.Loads;
Truncates += RHS.Truncates;
CrossRegisterBanksCopies += RHS.CrossRegisterBanksCopies;
ZExts += RHS.ZExts;
Shift += RHS.Shift;
return *this;
}
bool operator==(const Cost &RHS) const {
return Loads == RHS.Loads && Truncates == RHS.Truncates &&
CrossRegisterBanksCopies == RHS.CrossRegisterBanksCopies &&
ZExts == RHS.ZExts && Shift == RHS.Shift;
}
bool operator!=(const Cost &RHS) const { return !(*this == RHS); }
bool operator<(const Cost &RHS) const {
// Assume cross register banks copies are as expensive as loads.
// FIXME: Do we want some more target hooks?
unsigned ExpensiveOpsLHS = Loads + CrossRegisterBanksCopies;
unsigned ExpensiveOpsRHS = RHS.Loads + RHS.CrossRegisterBanksCopies;
// Unless we are optimizing for code size, consider the
// expensive operation first.
if (!ForCodeSize && ExpensiveOpsLHS != ExpensiveOpsRHS)
return ExpensiveOpsLHS < ExpensiveOpsRHS;
return (Truncates + ZExts + Shift + ExpensiveOpsLHS) <
(RHS.Truncates + RHS.ZExts + RHS.Shift + ExpensiveOpsRHS);
}
bool operator>(const Cost &RHS) const { return RHS < *this; }
bool operator<=(const Cost &RHS) const { return !(RHS < *this); }
bool operator>=(const Cost &RHS) const { return !(*this < RHS); }
};
// The last instruction that represent the slice. This should be a
// truncate instruction.
SDNode *Inst;
// The original load instruction.
LoadSDNode *Origin;
// The right shift amount in bits from the original load.
unsigned Shift;
// The DAG from which Origin came from.
// This is used to get some contextual information about legal types, etc.
SelectionDAG *DAG;
LoadedSlice(SDNode *Inst = nullptr, LoadSDNode *Origin = nullptr,
unsigned Shift = 0, SelectionDAG *DAG = nullptr)
: Inst(Inst), Origin(Origin), Shift(Shift), DAG(DAG) {}
/// Get the bits used in a chunk of bits \p BitWidth large.
/// \return Result is \p BitWidth and has used bits set to 1 and
/// not used bits set to 0.
APInt getUsedBits() const {
// Reproduce the trunc(lshr) sequence:
// - Start from the truncated value.
// - Zero extend to the desired bit width.
// - Shift left.
assert(Origin && "No original load to compare against.");
unsigned BitWidth = Origin->getValueSizeInBits(0);
assert(Inst && "This slice is not bound to an instruction");
assert(Inst->getValueSizeInBits(0) <= BitWidth &&
"Extracted slice is bigger than the whole type!");
APInt UsedBits(Inst->getValueSizeInBits(0), 0);
UsedBits.setAllBits();
UsedBits = UsedBits.zext(BitWidth);
UsedBits <<= Shift;
return UsedBits;
}
/// Get the size of the slice to be loaded in bytes.
unsigned getLoadedSize() const {
unsigned SliceSize = getUsedBits().countPopulation();
assert(!(SliceSize & 0x7) && "Size is not a multiple of a byte.");
return SliceSize / 8;
}
/// Get the type that will be loaded for this slice.
/// Note: This may not be the final type for the slice.
EVT getLoadedType() const {
assert(DAG && "Missing context");
LLVMContext &Ctxt = *DAG->getContext();
return EVT::getIntegerVT(Ctxt, getLoadedSize() * 8);
}
/// Get the alignment of the load used for this slice.
Align getAlign() const {
Align Alignment = Origin->getAlign();
uint64_t Offset = getOffsetFromBase();
if (Offset != 0)
Alignment = commonAlignment(Alignment, Alignment.value() + Offset);
return Alignment;
}
/// Check if this slice can be rewritten with legal operations.
bool isLegal() const {
// An invalid slice is not legal.
if (!Origin || !Inst || !DAG)
return false;
// Offsets are for indexed load only, we do not handle that.
if (!Origin->getOffset().isUndef())
return false;
const TargetLowering &TLI = DAG->getTargetLoweringInfo();
// Check that the type is legal.
EVT SliceType = getLoadedType();
if (!TLI.isTypeLegal(SliceType))
return false;
// Check that the load is legal for this type.
if (!TLI.isOperationLegal(ISD::LOAD, SliceType))
return false;
// Check that the offset can be computed.
// 1. Check its type.
EVT PtrType = Origin->getBasePtr().getValueType();
if (PtrType == MVT::Untyped || PtrType.isExtended())
return false;
// 2. Check that it fits in the immediate.
if (!TLI.isLegalAddImmediate(getOffsetFromBase()))
return false;
// 3. Check that the computation is legal.
if (!TLI.isOperationLegal(ISD::ADD, PtrType))
return false;
// Check that the zext is legal if it needs one.
EVT TruncateType = Inst->getValueType(0);
if (TruncateType != SliceType &&
!TLI.isOperationLegal(ISD::ZERO_EXTEND, TruncateType))
return false;
return true;
}
/// Get the offset in bytes of this slice in the original chunk of
/// bits.
/// \pre DAG != nullptr.
uint64_t getOffsetFromBase() const {
assert(DAG && "Missing context.");
bool IsBigEndian = DAG->getDataLayout().isBigEndian();
assert(!(Shift & 0x7) && "Shifts not aligned on Bytes are not supported.");
uint64_t Offset = Shift / 8;
unsigned TySizeInBytes = Origin->getValueSizeInBits(0) / 8;
assert(!(Origin->getValueSizeInBits(0) & 0x7) &&
"The size of the original loaded type is not a multiple of a"
" byte.");
// If Offset is bigger than TySizeInBytes, it means we are loading all
// zeros. This should have been optimized before in the process.
assert(TySizeInBytes > Offset &&
"Invalid shift amount for given loaded size");
if (IsBigEndian)
Offset = TySizeInBytes - Offset - getLoadedSize();
return Offset;
}
/// Generate the sequence of instructions to load the slice
/// represented by this object and redirect the uses of this slice to
/// this new sequence of instructions.
/// \pre this->Inst && this->Origin are valid Instructions and this
/// object passed the legal check: LoadedSlice::isLegal returned true.
/// \return The last instruction of the sequence used to load the slice.
SDValue loadSlice() const {
assert(Inst && Origin && "Unable to replace a non-existing slice.");
const SDValue &OldBaseAddr = Origin->getBasePtr();
SDValue BaseAddr = OldBaseAddr;
// Get the offset in that chunk of bytes w.r.t. the endianness.
int64_t Offset = static_cast<int64_t>(getOffsetFromBase());
assert(Offset >= 0 && "Offset too big to fit in int64_t!");
if (Offset) {
// BaseAddr = BaseAddr + Offset.
EVT ArithType = BaseAddr.getValueType();
SDLoc DL(Origin);
BaseAddr = DAG->getNode(ISD::ADD, DL, ArithType, BaseAddr,
DAG->getConstant(Offset, DL, ArithType));
}
// Create the type of the loaded slice according to its size.
EVT SliceType = getLoadedType();
// Create the load for the slice.
SDValue LastInst =
DAG->getLoad(SliceType, SDLoc(Origin), Origin->getChain(), BaseAddr,
Origin->getPointerInfo().getWithOffset(Offset), getAlign(),
Origin->getMemOperand()->getFlags());
// If the final type is not the same as the loaded type, this means that
// we have to pad with zero. Create a zero extend for that.
EVT FinalType = Inst->getValueType(0);
if (SliceType != FinalType)
LastInst =
DAG->getNode(ISD::ZERO_EXTEND, SDLoc(LastInst), FinalType, LastInst);
return LastInst;
}
/// Check if this slice can be merged with an expensive cross register
/// bank copy. E.g.,
/// i = load i32
/// f = bitcast i32 i to float
bool canMergeExpensiveCrossRegisterBankCopy() const {
if (!Inst || !Inst->hasOneUse())
return false;
SDNode *Use = *Inst->use_begin();
if (Use->getOpcode() != ISD::BITCAST)
return false;
assert(DAG && "Missing context");
const TargetLowering &TLI = DAG->getTargetLoweringInfo();
EVT ResVT = Use->getValueType(0);
const TargetRegisterClass *ResRC =
TLI.getRegClassFor(ResVT.getSimpleVT(), Use->isDivergent());
const TargetRegisterClass *ArgRC =
TLI.getRegClassFor(Use->getOperand(0).getValueType().getSimpleVT(),
Use->getOperand(0)->isDivergent());
if (ArgRC == ResRC || !TLI.isOperationLegal(ISD::LOAD, ResVT))
return false;
// At this point, we know that we perform a cross-register-bank copy.
// Check if it is expensive.
const TargetRegisterInfo *TRI = DAG->getSubtarget().getRegisterInfo();
// Assume bitcasts are cheap, unless both register classes do not
// explicitly share a common sub class.
if (!TRI || TRI->getCommonSubClass(ArgRC, ResRC))
return false;
// Check if it will be merged with the load.
// 1. Check the alignment / fast memory access constraint.
bool IsFast = false;
if (!TLI.allowsMemoryAccess(*DAG->getContext(), DAG->getDataLayout(), ResVT,
Origin->getAddressSpace(), getAlign(),
Origin->getMemOperand()->getFlags(), &IsFast) ||
!IsFast)
return false;
// 2. Check that the load is a legal operation for that type.
if (!TLI.isOperationLegal(ISD::LOAD, ResVT))
return false;
// 3. Check that we do not have a zext in the way.
if (Inst->getValueType(0) != getLoadedType())
return false;
return true;
}
};
} // end anonymous namespace
/// Check that all bits set in \p UsedBits form a dense region, i.e.,
/// \p UsedBits looks like 0..0 1..1 0..0.
static bool areUsedBitsDense(const APInt &UsedBits) {
// If all the bits are one, this is dense!
if (UsedBits.isAllOnes())
return true;
// Get rid of the unused bits on the right.
APInt NarrowedUsedBits = UsedBits.lshr(UsedBits.countTrailingZeros());
// Get rid of the unused bits on the left.
if (NarrowedUsedBits.countLeadingZeros())
NarrowedUsedBits = NarrowedUsedBits.trunc(NarrowedUsedBits.getActiveBits());
// Check that the chunk of bits is completely used.
return NarrowedUsedBits.isAllOnes();
}
/// Check whether or not \p First and \p Second are next to each other
/// in memory. This means that there is no hole between the bits loaded
/// by \p First and the bits loaded by \p Second.
static bool areSlicesNextToEachOther(const LoadedSlice &First,
const LoadedSlice &Second) {
assert(First.Origin == Second.Origin && First.Origin &&
"Unable to match different memory origins.");
APInt UsedBits = First.getUsedBits();
assert((UsedBits & Second.getUsedBits()) == 0 &&
"Slices are not supposed to overlap.");
UsedBits |= Second.getUsedBits();
return areUsedBitsDense(UsedBits);
}
/// Adjust the \p GlobalLSCost according to the target
/// paring capabilities and the layout of the slices.
/// \pre \p GlobalLSCost should account for at least as many loads as
/// there is in the slices in \p LoadedSlices.
static void adjustCostForPairing(SmallVectorImpl<LoadedSlice> &LoadedSlices,
LoadedSlice::Cost &GlobalLSCost) {
unsigned NumberOfSlices = LoadedSlices.size();
// If there is less than 2 elements, no pairing is possible.
if (NumberOfSlices < 2)
return;
// Sort the slices so that elements that are likely to be next to each
// other in memory are next to each other in the list.
llvm::sort(LoadedSlices, [](const LoadedSlice &LHS, const LoadedSlice &RHS) {
assert(LHS.Origin == RHS.Origin && "Different bases not implemented.");
return LHS.getOffsetFromBase() < RHS.getOffsetFromBase();
});
const TargetLowering &TLI = LoadedSlices[0].DAG->getTargetLoweringInfo();
// First (resp. Second) is the first (resp. Second) potentially candidate
// to be placed in a paired load.
const LoadedSlice *First = nullptr;
const LoadedSlice *Second = nullptr;
for (unsigned CurrSlice = 0; CurrSlice < NumberOfSlices; ++CurrSlice,
// Set the beginning of the pair.
First = Second) {
Second = &LoadedSlices[CurrSlice];
// If First is NULL, it means we start a new pair.
// Get to the next slice.
if (!First)
continue;
EVT LoadedType = First->getLoadedType();
// If the types of the slices are different, we cannot pair them.
if (LoadedType != Second->getLoadedType())
continue;
// Check if the target supplies paired loads for this type.
Align RequiredAlignment;
if (!TLI.hasPairedLoad(LoadedType, RequiredAlignment)) {
// move to the next pair, this type is hopeless.
Second = nullptr;
continue;
}
// Check if we meet the alignment requirement.
if (First->getAlign() < RequiredAlignment)
continue;
// Check that both loads are next to each other in memory.
if (!areSlicesNextToEachOther(*First, *Second))
continue;
assert(GlobalLSCost.Loads > 0 && "We save more loads than we created!");
--GlobalLSCost.Loads;
// Move to the next pair.
Second = nullptr;
}
}
/// Check the profitability of all involved LoadedSlice.
/// Currently, it is considered profitable if there is exactly two
/// involved slices (1) which are (2) next to each other in memory, and
/// whose cost (\see LoadedSlice::Cost) is smaller than the original load (3).
///
/// Note: The order of the elements in \p LoadedSlices may be modified, but not
/// the elements themselves.
///
/// FIXME: When the cost model will be mature enough, we can relax
/// constraints (1) and (2).
static bool isSlicingProfitable(SmallVectorImpl<LoadedSlice> &LoadedSlices,
const APInt &UsedBits, bool ForCodeSize) {
unsigned NumberOfSlices = LoadedSlices.size();
if (StressLoadSlicing)
return NumberOfSlices > 1;
// Check (1).
if (NumberOfSlices != 2)
return false;
// Check (2).
if (!areUsedBitsDense(UsedBits))
return false;
// Check (3).
LoadedSlice::Cost OrigCost(ForCodeSize), GlobalSlicingCost(ForCodeSize);
// The original code has one big load.
OrigCost.Loads = 1;
for (unsigned CurrSlice = 0; CurrSlice < NumberOfSlices; ++CurrSlice) {
const LoadedSlice &LS = LoadedSlices[CurrSlice];
// Accumulate the cost of all the slices.
LoadedSlice::Cost SliceCost(LS, ForCodeSize);
GlobalSlicingCost += SliceCost;
// Account as cost in the original configuration the gain obtained
// with the current slices.
OrigCost.addSliceGain(LS);
}
// If the target supports paired load, adjust the cost accordingly.
adjustCostForPairing(LoadedSlices, GlobalSlicingCost);
return OrigCost > GlobalSlicingCost;
}
/// If the given load, \p LI, is used only by trunc or trunc(lshr)
/// operations, split it in the various pieces being extracted.
///
/// This sort of thing is introduced by SROA.
/// This slicing takes care not to insert overlapping loads.
/// \pre LI is a simple load (i.e., not an atomic or volatile load).
bool DAGCombiner::SliceUpLoad(SDNode *N) {
if (Level < AfterLegalizeDAG)
return false;
LoadSDNode *LD = cast<LoadSDNode>(N);
if (!LD->isSimple() || !ISD::isNormalLoad(LD) ||
!LD->getValueType(0).isInteger())
return false;
// The algorithm to split up a load of a scalable vector into individual
// elements currently requires knowing the length of the loaded type,
// so will need adjusting to work on scalable vectors.
if (LD->getValueType(0).isScalableVector())
return false;
// Keep track of already used bits to detect overlapping values.
// In that case, we will just abort the transformation.
APInt UsedBits(LD->getValueSizeInBits(0), 0);
SmallVector<LoadedSlice, 4> LoadedSlices;
// Check if this load is used as several smaller chunks of bits.
// Basically, look for uses in trunc or trunc(lshr) and record a new chain
// of computation for each trunc.
for (SDNode::use_iterator UI = LD->use_begin(), UIEnd = LD->use_end();
UI != UIEnd; ++UI) {
// Skip the uses of the chain.
if (UI.getUse().getResNo() != 0)
continue;
SDNode *User = *UI;
unsigned Shift = 0;
// Check if this is a trunc(lshr).
if (User->getOpcode() == ISD::SRL && User->hasOneUse() &&
isa<ConstantSDNode>(User->getOperand(1))) {
Shift = User->getConstantOperandVal(1);
User = *User->use_begin();
}
// At this point, User is a Truncate, iff we encountered, trunc or
// trunc(lshr).
if (User->getOpcode() != ISD::TRUNCATE)
return false;
// The width of the type must be a power of 2 and greater than 8-bits.
// Otherwise the load cannot be represented in LLVM IR.
// Moreover, if we shifted with a non-8-bits multiple, the slice
// will be across several bytes. We do not support that.
unsigned Width = User->getValueSizeInBits(0);
if (Width < 8 || !isPowerOf2_32(Width) || (Shift & 0x7))
return false;
// Build the slice for this chain of computations.
LoadedSlice LS(User, LD, Shift, &DAG);
APInt CurrentUsedBits = LS.getUsedBits();
// Check if this slice overlaps with another.
if ((CurrentUsedBits & UsedBits) != 0)
return false;
// Update the bits used globally.
UsedBits |= CurrentUsedBits;
// Check if the new slice would be legal.
if (!LS.isLegal())
return false;
// Record the slice.
LoadedSlices.push_back(LS);
}
// Abort slicing if it does not seem to be profitable.
if (!isSlicingProfitable(LoadedSlices, UsedBits, ForCodeSize))
return false;
++SlicedLoads;
// Rewrite each chain to use an independent load.
// By construction, each chain can be represented by a unique load.
// Prepare the argument for the new token factor for all the slices.
SmallVector<SDValue, 8> ArgChains;
for (const LoadedSlice &LS : LoadedSlices) {
SDValue SliceInst = LS.loadSlice();
CombineTo(LS.Inst, SliceInst, true);
if (SliceInst.getOpcode() != ISD::LOAD)
SliceInst = SliceInst.getOperand(0);
assert(SliceInst->getOpcode() == ISD::LOAD &&
"It takes more than a zext to get to the loaded slice!!");
ArgChains.push_back(SliceInst.getValue(1));
}
SDValue Chain = DAG.getNode(ISD::TokenFactor, SDLoc(LD), MVT::Other,
ArgChains);
DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), Chain);
AddToWorklist(Chain.getNode());
return true;
}
/// Check to see if V is (and load (ptr), imm), where the load is having
/// specific bytes cleared out. If so, return the byte size being masked out
/// and the shift amount.
static std::pair<unsigned, unsigned>
CheckForMaskedLoad(SDValue V, SDValue Ptr, SDValue Chain) {
std::pair<unsigned, unsigned> Result(0, 0);
// Check for the structure we're looking for.
if (V->getOpcode() != ISD::AND ||
!isa<ConstantSDNode>(V->getOperand(1)) ||
!ISD::isNormalLoad(V->getOperand(0).getNode()))
return Result;
// Check the chain and pointer.
LoadSDNode *LD = cast<LoadSDNode>(V->getOperand(0));
if (LD->getBasePtr() != Ptr) return Result; // Not from same pointer.
// This only handles simple types.
if (V.getValueType() != MVT::i16 &&
V.getValueType() != MVT::i32 &&
V.getValueType() != MVT::i64)
return Result;
// Check the constant mask. Invert it so that the bits being masked out are
// 0 and the bits being kept are 1. Use getSExtValue so that leading bits
// follow the sign bit for uniformity.
uint64_t NotMask = ~cast<ConstantSDNode>(V->getOperand(1))->getSExtValue();
unsigned NotMaskLZ = countLeadingZeros(NotMask);
if (NotMaskLZ & 7) return Result; // Must be multiple of a byte.
unsigned NotMaskTZ = countTrailingZeros(NotMask);
if (NotMaskTZ & 7) return Result; // Must be multiple of a byte.
if (NotMaskLZ == 64) return Result; // All zero mask.
// See if we have a continuous run of bits. If so, we have 0*1+0*
if (countTrailingOnes(NotMask >> NotMaskTZ) + NotMaskTZ + NotMaskLZ != 64)
return Result;
// Adjust NotMaskLZ down to be from the actual size of the int instead of i64.
if (V.getValueType() != MVT::i64 && NotMaskLZ)
NotMaskLZ -= 64-V.getValueSizeInBits();
unsigned MaskedBytes = (V.getValueSizeInBits()-NotMaskLZ-NotMaskTZ)/8;
switch (MaskedBytes) {
case 1:
case 2:
case 4: break;
default: return Result; // All one mask, or 5-byte mask.
}
// Verify that the first bit starts at a multiple of mask so that the access
// is aligned the same as the access width.
if (NotMaskTZ && NotMaskTZ/8 % MaskedBytes) return Result;
// For narrowing to be valid, it must be the case that the load the
// immediately preceding memory operation before the store.
if (LD == Chain.getNode())
; // ok.
else if (Chain->getOpcode() == ISD::TokenFactor &&
SDValue(LD, 1).hasOneUse()) {
// LD has only 1 chain use so they are no indirect dependencies.
if (!LD->isOperandOf(Chain.getNode()))
return Result;
} else
return Result; // Fail.
Result.first = MaskedBytes;
Result.second = NotMaskTZ/8;
return Result;
}
/// Check to see if IVal is something that provides a value as specified by
/// MaskInfo. If so, replace the specified store with a narrower store of
/// truncated IVal.
static SDValue
ShrinkLoadReplaceStoreWithStore(const std::pair<unsigned, unsigned> &MaskInfo,
SDValue IVal, StoreSDNode *St,
DAGCombiner *DC) {
unsigned NumBytes = MaskInfo.first;
unsigned ByteShift = MaskInfo.second;
SelectionDAG &DAG = DC->getDAG();
// Check to see if IVal is all zeros in the part being masked in by the 'or'
// that uses this. If not, this is not a replacement.
APInt Mask = ~APInt::getBitsSet(IVal.getValueSizeInBits(),
ByteShift*8, (ByteShift+NumBytes)*8);
if (!DAG.MaskedValueIsZero(IVal, Mask)) return SDValue();
// Check that it is legal on the target to do this. It is legal if the new
// VT we're shrinking to (i8/i16/i32) is legal or we're still before type
// legalization (and the target doesn't explicitly think this is a bad idea).
MVT VT = MVT::getIntegerVT(NumBytes * 8);
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
if (!DC->isTypeLegal(VT))
return SDValue();
if (St->getMemOperand() &&
!TLI.allowsMemoryAccess(*DAG.getContext(), DAG.getDataLayout(), VT,
*St->getMemOperand()))
return SDValue();
// Okay, we can do this! Replace the 'St' store with a store of IVal that is
// shifted by ByteShift and truncated down to NumBytes.
if (ByteShift) {
SDLoc DL(IVal);
IVal = DAG.getNode(ISD::SRL, DL, IVal.getValueType(), IVal,
DAG.getConstant(ByteShift*8, DL,
DC->getShiftAmountTy(IVal.getValueType())));
}
// Figure out the offset for the store and the alignment of the access.
unsigned StOffset;
if (DAG.getDataLayout().isLittleEndian())
StOffset = ByteShift;
else
StOffset = IVal.getValueType().getStoreSize() - ByteShift - NumBytes;
SDValue Ptr = St->getBasePtr();
if (StOffset) {
SDLoc DL(IVal);
Ptr = DAG.getMemBasePlusOffset(Ptr, TypeSize::Fixed(StOffset), DL);
}
// Truncate down to the new size.
IVal = DAG.getNode(ISD::TRUNCATE, SDLoc(IVal), VT, IVal);
++OpsNarrowed;
return DAG
.getStore(St->getChain(), SDLoc(St), IVal, Ptr,
St->getPointerInfo().getWithOffset(StOffset),
St->getOriginalAlign());
}
/// Look for sequence of load / op / store where op is one of 'or', 'xor', and
/// 'and' of immediates. If 'op' is only touching some of the loaded bits, try
/// narrowing the load and store if it would end up being a win for performance
/// or code size.
SDValue DAGCombiner::ReduceLoadOpStoreWidth(SDNode *N) {
StoreSDNode *ST = cast<StoreSDNode>(N);
if (!ST->isSimple())
return SDValue();
SDValue Chain = ST->getChain();
SDValue Value = ST->getValue();
SDValue Ptr = ST->getBasePtr();
EVT VT = Value.getValueType();
if (ST->isTruncatingStore() || VT.isVector())
return SDValue();
unsigned Opc = Value.getOpcode();
if ((Opc != ISD::OR && Opc != ISD::XOR && Opc != ISD::AND) ||
!Value.hasOneUse())
return SDValue();
// If this is "store (or X, Y), P" and X is "(and (load P), cst)", where cst
// is a byte mask indicating a consecutive number of bytes, check to see if
// Y is known to provide just those bytes. If so, we try to replace the
// load + replace + store sequence with a single (narrower) store, which makes
// the load dead.
if (Opc == ISD::OR && EnableShrinkLoadReplaceStoreWithStore) {
std::pair<unsigned, unsigned> MaskedLoad;
MaskedLoad = CheckForMaskedLoad(Value.getOperand(0), Ptr, Chain);
if (MaskedLoad.first)
if (SDValue NewST = ShrinkLoadReplaceStoreWithStore(MaskedLoad,
Value.getOperand(1), ST,this))
return NewST;
// Or is commutative, so try swapping X and Y.
MaskedLoad = CheckForMaskedLoad(Value.getOperand(1), Ptr, Chain);
if (MaskedLoad.first)
if (SDValue NewST = ShrinkLoadReplaceStoreWithStore(MaskedLoad,
Value.getOperand(0), ST,this))
return NewST;
}
if (!EnableReduceLoadOpStoreWidth)
return SDValue();
if (Value.getOperand(1).getOpcode() != ISD::Constant)
return SDValue();
SDValue N0 = Value.getOperand(0);
if (ISD::isNormalLoad(N0.getNode()) && N0.hasOneUse() &&
Chain == SDValue(N0.getNode(), 1)) {
LoadSDNode *LD = cast<LoadSDNode>(N0);
if (LD->getBasePtr() != Ptr ||
LD->getPointerInfo().getAddrSpace() !=
ST->getPointerInfo().getAddrSpace())
return SDValue();
// Find the type to narrow it the load / op / store to.
SDValue N1 = Value.getOperand(1);
unsigned BitWidth = N1.getValueSizeInBits();
APInt Imm = cast<ConstantSDNode>(N1)->getAPIntValue();
if (Opc == ISD::AND)
Imm ^= APInt::getAllOnes(BitWidth);
if (Imm == 0 || Imm.isAllOnes())
return SDValue();
unsigned ShAmt = Imm.countTrailingZeros();
unsigned MSB = BitWidth - Imm.countLeadingZeros() - 1;
unsigned NewBW = NextPowerOf2(MSB - ShAmt);
EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), NewBW);
// The narrowing should be profitable, the load/store operation should be
// legal (or custom) and the store size should be equal to the NewVT width.
while (NewBW < BitWidth &&
(NewVT.getStoreSizeInBits() != NewBW ||
!TLI.isOperationLegalOrCustom(Opc, NewVT) ||
!TLI.isNarrowingProfitable(VT, NewVT))) {
NewBW = NextPowerOf2(NewBW);
NewVT = EVT::getIntegerVT(*DAG.getContext(), NewBW);
}
if (NewBW >= BitWidth)
return SDValue();
// If the lsb changed does not start at the type bitwidth boundary,
// start at the previous one.
if (ShAmt % NewBW)
ShAmt = (((ShAmt + NewBW - 1) / NewBW) * NewBW) - NewBW;
APInt Mask = APInt::getBitsSet(BitWidth, ShAmt,
std::min(BitWidth, ShAmt + NewBW));
if ((Imm & Mask) == Imm) {
APInt NewImm = (Imm & Mask).lshr(ShAmt).trunc(NewBW);
if (Opc == ISD::AND)
NewImm ^= APInt::getAllOnes(NewBW);
uint64_t PtrOff = ShAmt / 8;
// For big endian targets, we need to adjust the offset to the pointer to
// load the correct bytes.
if (DAG.getDataLayout().isBigEndian())
PtrOff = (BitWidth + 7 - NewBW) / 8 - PtrOff;
bool IsFast = false;
Align NewAlign = commonAlignment(LD->getAlign(), PtrOff);
if (!TLI.allowsMemoryAccess(*DAG.getContext(), DAG.getDataLayout(), NewVT,
LD->getAddressSpace(), NewAlign,
LD->getMemOperand()->getFlags(), &IsFast) ||
!IsFast)
return SDValue();
SDValue NewPtr =
DAG.getMemBasePlusOffset(Ptr, TypeSize::Fixed(PtrOff), SDLoc(LD));
SDValue NewLD =
DAG.getLoad(NewVT, SDLoc(N0), LD->getChain(), NewPtr,
LD->getPointerInfo().getWithOffset(PtrOff), NewAlign,
LD->getMemOperand()->getFlags(), LD->getAAInfo());
SDValue NewVal = DAG.getNode(Opc, SDLoc(Value), NewVT, NewLD,
DAG.getConstant(NewImm, SDLoc(Value),
NewVT));
SDValue NewST =
DAG.getStore(Chain, SDLoc(N), NewVal, NewPtr,
ST->getPointerInfo().getWithOffset(PtrOff), NewAlign);
AddToWorklist(NewPtr.getNode());
AddToWorklist(NewLD.getNode());
AddToWorklist(NewVal.getNode());
WorklistRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(N0.getValue(1), NewLD.getValue(1));
++OpsNarrowed;
return NewST;
}
}
return SDValue();
}
/// For a given floating point load / store pair, if the load value isn't used
/// by any other operations, then consider transforming the pair to integer
/// load / store operations if the target deems the transformation profitable.
SDValue DAGCombiner::TransformFPLoadStorePair(SDNode *N) {
StoreSDNode *ST = cast<StoreSDNode>(N);
SDValue Value = ST->getValue();
if (ISD::isNormalStore(ST) && ISD::isNormalLoad(Value.getNode()) &&
Value.hasOneUse()) {
LoadSDNode *LD = cast<LoadSDNode>(Value);
EVT VT = LD->getMemoryVT();
if (!VT.isFloatingPoint() ||
VT != ST->getMemoryVT() ||
LD->isNonTemporal() ||
ST->isNonTemporal() ||
LD->getPointerInfo().getAddrSpace() != 0 ||
ST->getPointerInfo().getAddrSpace() != 0)
return SDValue();
TypeSize VTSize = VT.getSizeInBits();
// We don't know the size of scalable types at compile time so we cannot
// create an integer of the equivalent size.
if (VTSize.isScalable())
return SDValue();
bool FastLD = false, FastST = false;
EVT IntVT = EVT::getIntegerVT(*DAG.getContext(), VTSize.getFixedSize());
if (!TLI.isOperationLegal(ISD::LOAD, IntVT) ||
!TLI.isOperationLegal(ISD::STORE, IntVT) ||
!TLI.isDesirableToTransformToIntegerOp(ISD::LOAD, VT) ||
!TLI.isDesirableToTransformToIntegerOp(ISD::STORE, VT) ||
!TLI.allowsMemoryAccess(*DAG.getContext(), DAG.getDataLayout(), IntVT,
*LD->getMemOperand(), &FastLD) ||
!TLI.allowsMemoryAccess(*DAG.getContext(), DAG.getDataLayout(), IntVT,
*ST->getMemOperand(), &FastST) ||
!FastLD || !FastST)
return SDValue();
SDValue NewLD =
DAG.getLoad(IntVT, SDLoc(Value), LD->getChain(), LD->getBasePtr(),
LD->getPointerInfo(), LD->getAlign());
SDValue NewST =
DAG.getStore(ST->getChain(), SDLoc(N), NewLD, ST->getBasePtr(),
ST->getPointerInfo(), ST->getAlign());
AddToWorklist(NewLD.getNode());
AddToWorklist(NewST.getNode());
WorklistRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(Value.getValue(1), NewLD.getValue(1));
++LdStFP2Int;
return NewST;
}
return SDValue();
}
// This is a helper function for visitMUL to check the profitability
// of folding (mul (add x, c1), c2) -> (add (mul x, c2), c1*c2).
// MulNode is the original multiply, AddNode is (add x, c1),
// and ConstNode is c2.
//
// If the (add x, c1) has multiple uses, we could increase
// the number of adds if we make this transformation.
// It would only be worth doing this if we can remove a
// multiply in the process. Check for that here.
// To illustrate:
// (A + c1) * c3
// (A + c2) * c3
// We're checking for cases where we have common "c3 * A" expressions.
bool DAGCombiner::isMulAddWithConstProfitable(SDNode *MulNode, SDValue AddNode,
SDValue ConstNode) {
APInt Val;
// If the add only has one use, and the target thinks the folding is
// profitable or does not lead to worse code, this would be OK to do.
if (AddNode->hasOneUse() &&
TLI.isMulAddWithConstProfitable(AddNode, ConstNode))
return true;
// Walk all the users of the constant with which we're multiplying.
for (SDNode *Use : ConstNode->uses()) {
if (Use == MulNode) // This use is the one we're on right now. Skip it.
continue;
if (Use->getOpcode() == ISD::MUL) { // We have another multiply use.
SDNode *OtherOp;
SDNode *MulVar = AddNode.getOperand(0).getNode();
// OtherOp is what we're multiplying against the constant.
if (Use->getOperand(0) == ConstNode)
OtherOp = Use->getOperand(1).getNode();
else
OtherOp = Use->getOperand(0).getNode();
// Check to see if multiply is with the same operand of our "add".
//
// ConstNode = CONST
// Use = ConstNode * A <-- visiting Use. OtherOp is A.
// ...
// AddNode = (A + c1) <-- MulVar is A.
// = AddNode * ConstNode <-- current visiting instruction.
//
// If we make this transformation, we will have a common
// multiply (ConstNode * A) that we can save.
if (OtherOp == MulVar)
return true;
// Now check to see if a future expansion will give us a common
// multiply.
//
// ConstNode = CONST
// AddNode = (A + c1)
// ... = AddNode * ConstNode <-- current visiting instruction.
// ...
// OtherOp = (A + c2)
// Use = OtherOp * ConstNode <-- visiting Use.
//
// If we make this transformation, we will have a common
// multiply (CONST * A) after we also do the same transformation
// to the "t2" instruction.
if (OtherOp->getOpcode() == ISD::ADD &&
DAG.isConstantIntBuildVectorOrConstantInt(OtherOp->getOperand(1)) &&
OtherOp->getOperand(0).getNode() == MulVar)
return true;
}
}
// Didn't find a case where this would be profitable.
return false;
}
SDValue DAGCombiner::getMergeStoreChains(SmallVectorImpl<MemOpLink> &StoreNodes,
unsigned NumStores) {
SmallVector<SDValue, 8> Chains;
SmallPtrSet<const SDNode *, 8> Visited;
SDLoc StoreDL(StoreNodes[0].MemNode);
for (unsigned i = 0; i < NumStores; ++i) {
Visited.insert(StoreNodes[i].MemNode);
}
// don't include nodes that are children or repeated nodes.
for (unsigned i = 0; i < NumStores; ++i) {
if (Visited.insert(StoreNodes[i].MemNode->getChain().getNode()).second)
Chains.push_back(StoreNodes[i].MemNode->getChain());
}
assert(Chains.size() > 0 && "Chain should have generated a chain");
return DAG.getTokenFactor(StoreDL, Chains);
}
bool DAGCombiner::mergeStoresOfConstantsOrVecElts(
SmallVectorImpl<MemOpLink> &StoreNodes, EVT MemVT, unsigned NumStores,
bool IsConstantSrc, bool UseVector, bool UseTrunc) {
// Make sure we have something to merge.
if (NumStores < 2)
return false;
assert((!UseTrunc || !UseVector) &&
"This optimization cannot emit a vector truncating store");
// The latest Node in the DAG.
SDLoc DL(StoreNodes[0].MemNode);
TypeSize ElementSizeBits = MemVT.getStoreSizeInBits();
unsigned SizeInBits = NumStores * ElementSizeBits;
unsigned NumMemElts = MemVT.isVector() ? MemVT.getVectorNumElements() : 1;
Optional<MachineMemOperand::Flags> Flags;
AAMDNodes AAInfo;
for (unsigned I = 0; I != NumStores; ++I) {
StoreSDNode *St = cast<StoreSDNode>(StoreNodes[I].MemNode);
if (!Flags) {
Flags = St->getMemOperand()->getFlags();
AAInfo = St->getAAInfo();
continue;
}
// Skip merging if there's an inconsistent flag.
if (Flags != St->getMemOperand()->getFlags())
return false;
// Concatenate AA metadata.
AAInfo = AAInfo.concat(St->getAAInfo());
}
EVT StoreTy;
if (UseVector) {
unsigned Elts = NumStores * NumMemElts;
// Get the type for the merged vector store.
StoreTy = EVT::getVectorVT(*DAG.getContext(), MemVT.getScalarType(), Elts);
} else
StoreTy = EVT::getIntegerVT(*DAG.getContext(), SizeInBits);
SDValue StoredVal;
if (UseVector) {
if (IsConstantSrc) {
SmallVector<SDValue, 8> BuildVector;
for (unsigned I = 0; I != NumStores; ++I) {
StoreSDNode *St = cast<StoreSDNode>(StoreNodes[I].MemNode);
SDValue Val = St->getValue();
// If constant is of the wrong type, convert it now.
if (MemVT != Val.getValueType()) {
Val = peekThroughBitcasts(Val);
// Deal with constants of wrong size.
if (ElementSizeBits != Val.getValueSizeInBits()) {
EVT IntMemVT =
EVT::getIntegerVT(*DAG.getContext(), MemVT.getSizeInBits());
if (isa<ConstantFPSDNode>(Val)) {
// Not clear how to truncate FP values.
return false;
}
if (auto *C = dyn_cast<ConstantSDNode>(Val))
Val = DAG.getConstant(C->getAPIntValue()
.zextOrTrunc(Val.getValueSizeInBits())
.zextOrTrunc(ElementSizeBits),
SDLoc(C), IntMemVT);
}
// Make sure correctly size type is the correct type.
Val = DAG.getBitcast(MemVT, Val);
}
BuildVector.push_back(Val);
}
StoredVal = DAG.getNode(MemVT.isVector() ? ISD::CONCAT_VECTORS
: ISD::BUILD_VECTOR,
DL, StoreTy, BuildVector);
} else {
SmallVector<SDValue, 8> Ops;
for (unsigned i = 0; i < NumStores; ++i) {
StoreSDNode *St = cast<StoreSDNode>(StoreNodes[i].MemNode);
SDValue Val = peekThroughBitcasts(St->getValue());
// All operands of BUILD_VECTOR / CONCAT_VECTOR must be of
// type MemVT. If the underlying value is not the correct
// type, but it is an extraction of an appropriate vector we
// can recast Val to be of the correct type. This may require
// converting between EXTRACT_VECTOR_ELT and
// EXTRACT_SUBVECTOR.
if ((MemVT != Val.getValueType()) &&
(Val.getOpcode() == ISD::EXTRACT_VECTOR_ELT ||
Val.getOpcode() == ISD::EXTRACT_SUBVECTOR)) {
EVT MemVTScalarTy = MemVT.getScalarType();
// We may need to add a bitcast here to get types to line up.
if (MemVTScalarTy != Val.getValueType().getScalarType()) {
Val = DAG.getBitcast(MemVT, Val);
} else {
unsigned OpC = MemVT.isVector() ? ISD::EXTRACT_SUBVECTOR
: ISD::EXTRACT_VECTOR_ELT;
SDValue Vec = Val.getOperand(0);
SDValue Idx = Val.getOperand(1);
Val = DAG.getNode(OpC, SDLoc(Val), MemVT, Vec, Idx);
}
}
Ops.push_back(Val);
}
// Build the extracted vector elements back into a vector.
StoredVal = DAG.getNode(MemVT.isVector() ? ISD::CONCAT_VECTORS
: ISD::BUILD_VECTOR,
DL, StoreTy, Ops);
}
} else {
// We should always use a vector store when merging extracted vector
// elements, so this path implies a store of constants.
assert(IsConstantSrc && "Merged vector elements should use vector store");
APInt StoreInt(SizeInBits, 0);
// Construct a single integer constant which is made of the smaller
// constant inputs.
bool IsLE = DAG.getDataLayout().isLittleEndian();
for (unsigned i = 0; i < NumStores; ++i) {
unsigned Idx = IsLE ? (NumStores - 1 - i) : i;
StoreSDNode *St = cast<StoreSDNode>(StoreNodes[Idx].MemNode);
SDValue Val = St->getValue();
Val = peekThroughBitcasts(Val);
StoreInt <<= ElementSizeBits;
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Val)) {
StoreInt |= C->getAPIntValue()
.zextOrTrunc(ElementSizeBits)
.zextOrTrunc(SizeInBits);
} else if (ConstantFPSDNode *C = dyn_cast<ConstantFPSDNode>(Val)) {
StoreInt |= C->getValueAPF()
.bitcastToAPInt()
.zextOrTrunc(ElementSizeBits)
.zextOrTrunc(SizeInBits);
// If fp truncation is necessary give up for now.
if (MemVT.getSizeInBits() != ElementSizeBits)
return false;
} else {
llvm_unreachable("Invalid constant element type");
}
}
// Create the new Load and Store operations.
StoredVal = DAG.getConstant(StoreInt, DL, StoreTy);
}
LSBaseSDNode *FirstInChain = StoreNodes[0].MemNode;
SDValue NewChain = getMergeStoreChains(StoreNodes, NumStores);
// make sure we use trunc store if it's necessary to be legal.
SDValue NewStore;
if (!UseTrunc) {
NewStore = DAG.getStore(NewChain, DL, StoredVal, FirstInChain->getBasePtr(),
FirstInChain->getPointerInfo(),
FirstInChain->getAlign(), Flags.getValue(), AAInfo);
} else { // Must be realized as a trunc store
EVT LegalizedStoredValTy =
TLI.getTypeToTransformTo(*DAG.getContext(), StoredVal.getValueType());
unsigned LegalizedStoreSize = LegalizedStoredValTy.getSizeInBits();
ConstantSDNode *C = cast<ConstantSDNode>(StoredVal);
SDValue ExtendedStoreVal =
DAG.getConstant(C->getAPIntValue().zextOrTrunc(LegalizedStoreSize), DL,
LegalizedStoredValTy);
NewStore = DAG.getTruncStore(
NewChain, DL, ExtendedStoreVal, FirstInChain->getBasePtr(),
FirstInChain->getPointerInfo(), StoredVal.getValueType() /*TVT*/,
FirstInChain->getAlign(), Flags.getValue(), AAInfo);
}
// Replace all merged stores with the new store.
for (unsigned i = 0; i < NumStores; ++i)
CombineTo(StoreNodes[i].MemNode, NewStore);
AddToWorklist(NewChain.getNode());
return true;
}
void DAGCombiner::getStoreMergeCandidates(
StoreSDNode *St, SmallVectorImpl<MemOpLink> &StoreNodes,
SDNode *&RootNode) {
// This holds the base pointer, index, and the offset in bytes from the base
// pointer. We must have a base and an offset. Do not handle stores to undef
// base pointers.
BaseIndexOffset BasePtr = BaseIndexOffset::match(St, DAG);
if (!BasePtr.getBase().getNode() || BasePtr.getBase().isUndef())
return;
SDValue Val = peekThroughBitcasts(St->getValue());
StoreSource StoreSrc = getStoreSource(Val);
assert(StoreSrc != StoreSource::Unknown && "Expected known source for store");
// Match on loadbaseptr if relevant.
EVT MemVT = St->getMemoryVT();
BaseIndexOffset LBasePtr;
EVT LoadVT;
if (StoreSrc == StoreSource::Load) {
auto *Ld = cast<LoadSDNode>(Val);
LBasePtr = BaseIndexOffset::match(Ld, DAG);
LoadVT = Ld->getMemoryVT();
// Load and store should be the same type.
if (MemVT != LoadVT)
return;
// Loads must only have one use.
if (!Ld->hasNUsesOfValue(1, 0))
return;
// The memory operands must not be volatile/indexed/atomic.
// TODO: May be able to relax for unordered atomics (see D66309)
if (!Ld->isSimple() || Ld->isIndexed())
return;
}
auto CandidateMatch = [&](StoreSDNode *Other, BaseIndexOffset &Ptr,
int64_t &Offset) -> bool {
// The memory operands must not be volatile/indexed/atomic.
// TODO: May be able to relax for unordered atomics (see D66309)
if (!Other->isSimple() || Other->isIndexed())
return false;
// Don't mix temporal stores with non-temporal stores.
if (St->isNonTemporal() != Other->isNonTemporal())
return false;
SDValue OtherBC = peekThroughBitcasts(Other->getValue());
// Allow merging constants of different types as integers.
bool NoTypeMatch = (MemVT.isInteger()) ? !MemVT.bitsEq(Other->getMemoryVT())
: Other->getMemoryVT() != MemVT;
switch (StoreSrc) {
case StoreSource::Load: {
if (NoTypeMatch)
return false;
// The Load's Base Ptr must also match.
auto *OtherLd = dyn_cast<LoadSDNode>(OtherBC);
if (!OtherLd)
return false;
BaseIndexOffset LPtr = BaseIndexOffset::match(OtherLd, DAG);
if (LoadVT != OtherLd->getMemoryVT())
return false;
// Loads must only have one use.
if (!OtherLd->hasNUsesOfValue(1, 0))
return false;
// The memory operands must not be volatile/indexed/atomic.
// TODO: May be able to relax for unordered atomics (see D66309)
if (!OtherLd->isSimple() || OtherLd->isIndexed())
return false;
// Don't mix temporal loads with non-temporal loads.
if (cast<LoadSDNode>(Val)->isNonTemporal() != OtherLd->isNonTemporal())
return false;
if (!(LBasePtr.equalBaseIndex(LPtr, DAG)))
return false;
break;
}
case StoreSource::Constant:
if (NoTypeMatch)
return false;
if (!isIntOrFPConstant(OtherBC))
return false;
break;
case StoreSource::Extract:
// Do not merge truncated stores here.
if (Other->isTruncatingStore())
return false;
if (!MemVT.bitsEq(OtherBC.getValueType()))
return false;
if (OtherBC.getOpcode() != ISD::EXTRACT_VECTOR_ELT &&
OtherBC.getOpcode() != ISD::EXTRACT_SUBVECTOR)
return false;
break;
default:
llvm_unreachable("Unhandled store source for merging");
}
Ptr = BaseIndexOffset::match(Other, DAG);
return (BasePtr.equalBaseIndex(Ptr, DAG, Offset));
};
// Check if the pair of StoreNode and the RootNode already bail out many
// times which is over the limit in dependence check.
auto OverLimitInDependenceCheck = [&](SDNode *StoreNode,
SDNode *RootNode) -> bool {
auto RootCount = StoreRootCountMap.find(StoreNode);
return RootCount != StoreRootCountMap.end() &&
RootCount->second.first == RootNode &&
RootCount->second.second > StoreMergeDependenceLimit;
};
auto TryToAddCandidate = [&](SDNode::use_iterator UseIter) {
// This must be a chain use.
if (UseIter.getOperandNo() != 0)
return;
if (auto *OtherStore = dyn_cast<StoreSDNode>(*UseIter)) {
BaseIndexOffset Ptr;
int64_t PtrDiff;
if (CandidateMatch(OtherStore, Ptr, PtrDiff) &&
!OverLimitInDependenceCheck(OtherStore, RootNode))
StoreNodes.push_back(MemOpLink(OtherStore, PtrDiff));
}
};
// We looking for a root node which is an ancestor to all mergable
// stores. We search up through a load, to our root and then down
// through all children. For instance we will find Store{1,2,3} if
// St is Store1, Store2. or Store3 where the root is not a load
// which always true for nonvolatile ops. TODO: Expand
// the search to find all valid candidates through multiple layers of loads.
//
// Root
// |-------|-------|
// Load Load Store3
// | |
// Store1 Store2
//
// FIXME: We should be able to climb and
// descend TokenFactors to find candidates as well.
RootNode = St->getChain().getNode();
unsigned NumNodesExplored = 0;
const unsigned MaxSearchNodes = 1024;
if (auto *Ldn = dyn_cast<LoadSDNode>(RootNode)) {
RootNode = Ldn->getChain().getNode();
for (auto I = RootNode->use_begin(), E = RootNode->use_end();
I != E && NumNodesExplored < MaxSearchNodes; ++I, ++NumNodesExplored) {
if (I.getOperandNo() == 0 && isa<LoadSDNode>(*I)) { // walk down chain
for (auto I2 = (*I)->use_begin(), E2 = (*I)->use_end(); I2 != E2; ++I2)
TryToAddCandidate(I2);
}
// Check stores that depend on the root (e.g. Store 3 in the chart above).
if (I.getOperandNo() == 0 && isa<StoreSDNode>(*I)) {
TryToAddCandidate(I);
}
}
} else {
for (auto I = RootNode->use_begin(), E = RootNode->use_end();
I != E && NumNodesExplored < MaxSearchNodes; ++I, ++NumNodesExplored)
TryToAddCandidate(I);
}
}
// We need to check that merging these stores does not cause a loop in the
// DAG. Any store candidate may depend on another candidate indirectly through
// its operands. Check in parallel by searching up from operands of candidates.
bool DAGCombiner::checkMergeStoreCandidatesForDependencies(
SmallVectorImpl<MemOpLink> &StoreNodes, unsigned NumStores,
SDNode *RootNode) {
// FIXME: We should be able to truncate a full search of
// predecessors by doing a BFS and keeping tabs the originating
// stores from which worklist nodes come from in a similar way to
// TokenFactor simplfication.
SmallPtrSet<const SDNode *, 32> Visited;
SmallVector<const SDNode *, 8> Worklist;
// RootNode is a predecessor to all candidates so we need not search
// past it. Add RootNode (peeking through TokenFactors). Do not count
// these towards size check.
Worklist.push_back(RootNode);
while (!Worklist.empty()) {
auto N = Worklist.pop_back_val();
if (!Visited.insert(N).second)
continue; // Already present in Visited.
if (N->getOpcode() == ISD::TokenFactor) {
for (SDValue Op : N->ops())
Worklist.push_back(Op.getNode());
}
}
// Don't count pruning nodes towards max.
unsigned int Max = 1024 + Visited.size();
// Search Ops of store candidates.
for (unsigned i = 0; i < NumStores; ++i) {
SDNode *N = StoreNodes[i].MemNode;
// Of the 4 Store Operands:
// * Chain (Op 0) -> We have already considered these
// in candidate selection, but only by following the
// chain dependencies. We could still have a chain
// dependency to a load, that has a non-chain dep to
// another load, that depends on a store, etc. So it is
// possible to have dependencies that consist of a mix
// of chain and non-chain deps, and we need to include
// chain operands in the analysis here..
// * Value (Op 1) -> Cycles may happen (e.g. through load chains)
// * Address (Op 2) -> Merged addresses may only vary by a fixed constant,
// but aren't necessarily fromt the same base node, so
// cycles possible (e.g. via indexed store).
// * (Op 3) -> Represents the pre or post-indexing offset (or undef for
// non-indexed stores). Not constant on all targets (e.g. ARM)
// and so can participate in a cycle.
for (unsigned j = 0; j < N->getNumOperands(); ++j)
Worklist.push_back(N->getOperand(j).getNode());
}
// Search through DAG. We can stop early if we find a store node.
for (unsigned i = 0; i < NumStores; ++i)
if (SDNode::hasPredecessorHelper(StoreNodes[i].MemNode, Visited, Worklist,
Max)) {
// If the searching bail out, record the StoreNode and RootNode in the
// StoreRootCountMap. If we have seen the pair many times over a limit,
// we won't add the StoreNode into StoreNodes set again.
if (Visited.size() >= Max) {
auto &RootCount = StoreRootCountMap[StoreNodes[i].MemNode];
if (RootCount.first == RootNode)
RootCount.second++;
else
RootCount = {RootNode, 1};
}
return false;
}
return true;
}
unsigned
DAGCombiner::getConsecutiveStores(SmallVectorImpl<MemOpLink> &StoreNodes,
int64_t ElementSizeBytes) const {
while (true) {
// Find a store past the width of the first store.
size_t StartIdx = 0;
while ((StartIdx + 1 < StoreNodes.size()) &&
StoreNodes[StartIdx].OffsetFromBase + ElementSizeBytes !=
StoreNodes[StartIdx + 1].OffsetFromBase)
++StartIdx;
// Bail if we don't have enough candidates to merge.
if (StartIdx + 1 >= StoreNodes.size())
return 0;
// Trim stores that overlapped with the first store.
if (StartIdx)
StoreNodes.erase(StoreNodes.begin(), StoreNodes.begin() + StartIdx);
// Scan the memory operations on the chain and find the first
// non-consecutive store memory address.
unsigned NumConsecutiveStores = 1;
int64_t StartAddress = StoreNodes[0].OffsetFromBase;
// Check that the addresses are consecutive starting from the second
// element in the list of stores.
for (unsigned i = 1, e = StoreNodes.size(); i < e; ++i) {
int64_t CurrAddress = StoreNodes[i].OffsetFromBase;
if (CurrAddress - StartAddress != (ElementSizeBytes * i))
break;
NumConsecutiveStores = i + 1;
}
if (NumConsecutiveStores > 1)
return NumConsecutiveStores;
// There are no consecutive stores at the start of the list.
// Remove the first store and try again.
StoreNodes.erase(StoreNodes.begin(), StoreNodes.begin() + 1);
}
}
bool DAGCombiner::tryStoreMergeOfConstants(
SmallVectorImpl<MemOpLink> &StoreNodes, unsigned NumConsecutiveStores,
EVT MemVT, SDNode *RootNode, bool AllowVectors) {
LLVMContext &Context = *DAG.getContext();
const DataLayout &DL = DAG.getDataLayout();
int64_t ElementSizeBytes = MemVT.getStoreSize();
unsigned NumMemElts = MemVT.isVector() ? MemVT.getVectorNumElements() : 1;
bool MadeChange = false;
// Store the constants into memory as one consecutive store.
while (NumConsecutiveStores >= 2) {
LSBaseSDNode *FirstInChain = StoreNodes[0].MemNode;
unsigned FirstStoreAS = FirstInChain->getAddressSpace();
Align FirstStoreAlign = FirstInChain->getAlign();
unsigned LastLegalType = 1;
unsigned LastLegalVectorType = 1;
bool LastIntegerTrunc = false;
bool NonZero = false;
unsigned FirstZeroAfterNonZero = NumConsecutiveStores;
for (unsigned i = 0; i < NumConsecutiveStores; ++i) {
StoreSDNode *ST = cast<StoreSDNode>(StoreNodes[i].MemNode);
SDValue StoredVal = ST->getValue();
bool IsElementZero = false;
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(StoredVal))
IsElementZero = C->isZero();
else if (ConstantFPSDNode *C = dyn_cast<ConstantFPSDNode>(StoredVal))
IsElementZero = C->getConstantFPValue()->isNullValue();
if (IsElementZero) {
if (NonZero && FirstZeroAfterNonZero == NumConsecutiveStores)
FirstZeroAfterNonZero = i;
}
NonZero |= !IsElementZero;
// Find a legal type for the constant store.
unsigned SizeInBits = (i + 1) * ElementSizeBytes * 8;
EVT StoreTy = EVT::getIntegerVT(Context, SizeInBits);
bool IsFast = false;
// Break early when size is too large to be legal.
if (StoreTy.getSizeInBits() > MaximumLegalStoreInBits)
break;
if (TLI.isTypeLegal(StoreTy) &&
TLI.canMergeStoresTo(FirstStoreAS, StoreTy,
DAG.getMachineFunction()) &&
TLI.allowsMemoryAccess(Context, DL, StoreTy,
*FirstInChain->getMemOperand(), &IsFast) &&
IsFast) {
LastIntegerTrunc = false;
LastLegalType = i + 1;
// Or check whether a truncstore is legal.
} else if (TLI.getTypeAction(Context, StoreTy) ==
TargetLowering::TypePromoteInteger) {
EVT LegalizedStoredValTy =
TLI.getTypeToTransformTo(Context, StoredVal.getValueType());
if (TLI.isTruncStoreLegal(LegalizedStoredValTy, StoreTy) &&
TLI.canMergeStoresTo(FirstStoreAS, LegalizedStoredValTy,
DAG.getMachineFunction()) &&
TLI.allowsMemoryAccess(Context, DL, StoreTy,
*FirstInChain->getMemOperand(), &IsFast) &&
IsFast) {
LastIntegerTrunc = true;
LastLegalType = i + 1;
}
}
// We only use vectors if the constant is known to be zero or the
// target allows it and the function is not marked with the
// noimplicitfloat attribute.
if ((!NonZero ||
TLI.storeOfVectorConstantIsCheap(MemVT, i + 1, FirstStoreAS)) &&
AllowVectors) {
// Find a legal type for the vector store.
unsigned Elts = (i + 1) * NumMemElts;
EVT Ty = EVT::getVectorVT(Context, MemVT.getScalarType(), Elts);
if (TLI.isTypeLegal(Ty) && TLI.isTypeLegal(MemVT) &&
TLI.canMergeStoresTo(FirstStoreAS, Ty, DAG.getMachineFunction()) &&
TLI.allowsMemoryAccess(Context, DL, Ty,
*FirstInChain->getMemOperand(), &IsFast) &&
IsFast)
LastLegalVectorType = i + 1;
}
}
bool UseVector = (LastLegalVectorType > LastLegalType) && AllowVectors;
unsigned NumElem = (UseVector) ? LastLegalVectorType : LastLegalType;
bool UseTrunc = LastIntegerTrunc && !UseVector;
// Check if we found a legal integer type that creates a meaningful
// merge.
if (NumElem < 2) {
// We know that candidate stores are in order and of correct
// shape. While there is no mergeable sequence from the
// beginning one may start later in the sequence. The only
// reason a merge of size N could have failed where another of
// the same size would not have, is if the alignment has
// improved or we've dropped a non-zero value. Drop as many
// candidates as we can here.
unsigned NumSkip = 1;
while ((NumSkip < NumConsecutiveStores) &&
(NumSkip < FirstZeroAfterNonZero) &&
(StoreNodes[NumSkip].MemNode->getAlign() <= FirstStoreAlign))
NumSkip++;
StoreNodes.erase(StoreNodes.begin(), StoreNodes.begin() + NumSkip);
NumConsecutiveStores -= NumSkip;
continue;
}
// Check that we can merge these candidates without causing a cycle.
if (!checkMergeStoreCandidatesForDependencies(StoreNodes, NumElem,
RootNode)) {
StoreNodes.erase(StoreNodes.begin(), StoreNodes.begin() + NumElem);
NumConsecutiveStores -= NumElem;
continue;
}
MadeChange |= mergeStoresOfConstantsOrVecElts(StoreNodes, MemVT, NumElem,
/*IsConstantSrc*/ true,
UseVector, UseTrunc);
// Remove merged stores for next iteration.
StoreNodes.erase(StoreNodes.begin(), StoreNodes.begin() + NumElem);
NumConsecutiveStores -= NumElem;
}
return MadeChange;
}
bool DAGCombiner::tryStoreMergeOfExtracts(
SmallVectorImpl<MemOpLink> &StoreNodes, unsigned NumConsecutiveStores,
EVT MemVT, SDNode *RootNode) {
LLVMContext &Context = *DAG.getContext();
const DataLayout &DL = DAG.getDataLayout();
unsigned NumMemElts = MemVT.isVector() ? MemVT.getVectorNumElements() : 1;
bool MadeChange = false;
// Loop on Consecutive Stores on success.
while (NumConsecutiveStores >= 2) {
LSBaseSDNode *FirstInChain = StoreNodes[0].MemNode;
unsigned FirstStoreAS = FirstInChain->getAddressSpace();
Align FirstStoreAlign = FirstInChain->getAlign();
unsigned NumStoresToMerge = 1;
for (unsigned i = 0; i < NumConsecutiveStores; ++i) {
// Find a legal type for the vector store.
unsigned Elts = (i + 1) * NumMemElts;
EVT Ty = EVT::getVectorVT(*DAG.getContext(), MemVT.getScalarType(), Elts);
bool IsFast = false;
// Break early when size is too large to be legal.
if (Ty.getSizeInBits() > MaximumLegalStoreInBits)
break;
if (TLI.isTypeLegal(Ty) &&
TLI.canMergeStoresTo(FirstStoreAS, Ty, DAG.getMachineFunction()) &&
TLI.allowsMemoryAccess(Context, DL, Ty,
*FirstInChain->getMemOperand(), &IsFast) &&
IsFast)
NumStoresToMerge = i + 1;
}
// Check if we found a legal integer type creating a meaningful
// merge.
if (NumStoresToMerge < 2) {
// We know that candidate stores are in order and of correct
// shape. While there is no mergeable sequence from the
// beginning one may start later in the sequence. The only
// reason a merge of size N could have failed where another of
// the same size would not have, is if the alignment has
// improved. Drop as many candidates as we can here.
unsigned NumSkip = 1;
while ((NumSkip < NumConsecutiveStores) &&
(StoreNodes[NumSkip].MemNode->getAlign() <= FirstStoreAlign))
NumSkip++;
StoreNodes.erase(StoreNodes.begin(), StoreNodes.begin() + NumSkip);
NumConsecutiveStores -= NumSkip;
continue;
}
// Check that we can merge these candidates without causing a cycle.
if (!checkMergeStoreCandidatesForDependencies(StoreNodes, NumStoresToMerge,
RootNode)) {
StoreNodes.erase(StoreNodes.begin(),
StoreNodes.begin() + NumStoresToMerge);
NumConsecutiveStores -= NumStoresToMerge;
continue;
}
MadeChange |= mergeStoresOfConstantsOrVecElts(
StoreNodes, MemVT, NumStoresToMerge, /*IsConstantSrc*/ false,
/*UseVector*/ true, /*UseTrunc*/ false);
StoreNodes.erase(StoreNodes.begin(), StoreNodes.begin() + NumStoresToMerge);
NumConsecutiveStores -= NumStoresToMerge;
}
return MadeChange;
}
bool DAGCombiner::tryStoreMergeOfLoads(SmallVectorImpl<MemOpLink> &StoreNodes,
unsigned NumConsecutiveStores, EVT MemVT,
SDNode *RootNode, bool AllowVectors,
bool IsNonTemporalStore,
bool IsNonTemporalLoad) {
LLVMContext &Context = *DAG.getContext();
const DataLayout &DL = DAG.getDataLayout();
int64_t ElementSizeBytes = MemVT.getStoreSize();
unsigned NumMemElts = MemVT.isVector() ? MemVT.getVectorNumElements() : 1;
bool MadeChange = false;
// Look for load nodes which are used by the stored values.
SmallVector<MemOpLink, 8> LoadNodes;
// Find acceptable loads. Loads need to have the same chain (token factor),
// must not be zext, volatile, indexed, and they must be consecutive.
BaseIndexOffset LdBasePtr;
for (unsigned i = 0; i < NumConsecutiveStores; ++i) {
StoreSDNode *St = cast<StoreSDNode>(StoreNodes[i].MemNode);
SDValue Val = peekThroughBitcasts(St->getValue());
LoadSDNode *Ld = cast<LoadSDNode>(Val);
BaseIndexOffset LdPtr = BaseIndexOffset::match(Ld, DAG);
// If this is not the first ptr that we check.
int64_t LdOffset = 0;
if (LdBasePtr.getBase().getNode()) {
// The base ptr must be the same.
if (!LdBasePtr.equalBaseIndex(LdPtr, DAG, LdOffset))
break;
} else {
// Check that all other base pointers are the same as this one.
LdBasePtr = LdPtr;
}
// We found a potential memory operand to merge.
LoadNodes.push_back(MemOpLink(Ld, LdOffset));
}
while (NumConsecutiveStores >= 2 && LoadNodes.size() >= 2) {
Align RequiredAlignment;
bool NeedRotate = false;
if (LoadNodes.size() == 2) {
// If we have load/store pair instructions and we only have two values,
// don't bother merging.
if (TLI.hasPairedLoad(MemVT, RequiredAlignment) &&
StoreNodes[0].MemNode->getAlign() >= RequiredAlignment) {
StoreNodes.erase(StoreNodes.begin(), StoreNodes.begin() + 2);
LoadNodes.erase(LoadNodes.begin(), LoadNodes.begin() + 2);
break;
}
// If the loads are reversed, see if we can rotate the halves into place.
int64_t Offset0 = LoadNodes[0].OffsetFromBase;
int64_t Offset1 = LoadNodes[1].OffsetFromBase;
EVT PairVT = EVT::getIntegerVT(Context, ElementSizeBytes * 8 * 2);
if (Offset0 - Offset1 == ElementSizeBytes &&
(hasOperation(ISD::ROTL, PairVT) ||
hasOperation(ISD::ROTR, PairVT))) {
std::swap(LoadNodes[0], LoadNodes[1]);
NeedRotate = true;
}
}
LSBaseSDNode *FirstInChain = StoreNodes[0].MemNode;
unsigned FirstStoreAS = FirstInChain->getAddressSpace();
Align FirstStoreAlign = FirstInChain->getAlign();
LoadSDNode *FirstLoad = cast<LoadSDNode>(LoadNodes[0].MemNode);
// Scan the memory operations on the chain and find the first
// non-consecutive load memory address. These variables hold the index in
// the store node array.
unsigned LastConsecutiveLoad = 1;
// This variable refers to the size and not index in the array.
unsigned LastLegalVectorType = 1;
unsigned LastLegalIntegerType = 1;
bool isDereferenceable = true;
bool DoIntegerTruncate = false;
int64_t StartAddress = LoadNodes[0].OffsetFromBase;
SDValue LoadChain = FirstLoad->getChain();
for (unsigned i = 1; i < LoadNodes.size(); ++i) {
// All loads must share the same chain.
if (LoadNodes[i].MemNode->getChain() != LoadChain)
break;
int64_t CurrAddress = LoadNodes[i].OffsetFromBase;
if (CurrAddress - StartAddress != (ElementSizeBytes * i))
break;
LastConsecutiveLoad = i;
if (isDereferenceable && !LoadNodes[i].MemNode->isDereferenceable())
isDereferenceable = false;
// Find a legal type for the vector store.
unsigned Elts = (i + 1) * NumMemElts;
EVT StoreTy = EVT::getVectorVT(Context, MemVT.getScalarType(), Elts);
// Break early when size is too large to be legal.
if (StoreTy.getSizeInBits() > MaximumLegalStoreInBits)
break;
bool IsFastSt = false;
bool IsFastLd = false;
// Don't try vector types if we need a rotate. We may still fail the
// legality checks for the integer type, but we can't handle the rotate
// case with vectors.
// FIXME: We could use a shuffle in place of the rotate.
if (!NeedRotate && TLI.isTypeLegal(StoreTy) &&
TLI.canMergeStoresTo(FirstStoreAS, StoreTy,
DAG.getMachineFunction()) &&
TLI.allowsMemoryAccess(Context, DL, StoreTy,
*FirstInChain->getMemOperand(), &IsFastSt) &&
IsFastSt &&
TLI.allowsMemoryAccess(Context, DL, StoreTy,
*FirstLoad->getMemOperand(), &IsFastLd) &&
IsFastLd) {
LastLegalVectorType = i + 1;
}
// Find a legal type for the integer store.
unsigned SizeInBits = (i + 1) * ElementSizeBytes * 8;
StoreTy = EVT::getIntegerVT(Context, SizeInBits);
if (TLI.isTypeLegal(StoreTy) &&
TLI.canMergeStoresTo(FirstStoreAS, StoreTy,
DAG.getMachineFunction()) &&
TLI.allowsMemoryAccess(Context, DL, StoreTy,
*FirstInChain->getMemOperand(), &IsFastSt) &&
IsFastSt &&
TLI.allowsMemoryAccess(Context, DL, StoreTy,
*FirstLoad->getMemOperand(), &IsFastLd) &&
IsFastLd) {
LastLegalIntegerType = i + 1;
DoIntegerTruncate = false;
// Or check whether a truncstore and extload is legal.
} else if (TLI.getTypeAction(Context, StoreTy) ==
TargetLowering::TypePromoteInteger) {
EVT LegalizedStoredValTy = TLI.getTypeToTransformTo(Context, StoreTy);
if (TLI.isTruncStoreLegal(LegalizedStoredValTy, StoreTy) &&
TLI.canMergeStoresTo(FirstStoreAS, LegalizedStoredValTy,
DAG.getMachineFunction()) &&
TLI.isLoadExtLegal(ISD::ZEXTLOAD, LegalizedStoredValTy, StoreTy) &&
TLI.isLoadExtLegal(ISD::SEXTLOAD, LegalizedStoredValTy, StoreTy) &&
TLI.isLoadExtLegal(ISD::EXTLOAD, LegalizedStoredValTy, StoreTy) &&
TLI.allowsMemoryAccess(Context, DL, StoreTy,
*FirstInChain->getMemOperand(), &IsFastSt) &&
IsFastSt &&
TLI.allowsMemoryAccess(Context, DL, StoreTy,
*FirstLoad->getMemOperand(), &IsFastLd) &&
IsFastLd) {
LastLegalIntegerType = i + 1;
DoIntegerTruncate = true;
}
}
}
// Only use vector types if the vector type is larger than the integer
// type. If they are the same, use integers.
bool UseVectorTy =
LastLegalVectorType > LastLegalIntegerType && AllowVectors;
unsigned LastLegalType =
std::max(LastLegalVectorType, LastLegalIntegerType);
// We add +1 here because the LastXXX variables refer to location while
// the NumElem refers to array/index size.
unsigned NumElem = std::min(NumConsecutiveStores, LastConsecutiveLoad + 1);
NumElem = std::min(LastLegalType, NumElem);
Align FirstLoadAlign = FirstLoad->getAlign();
if (NumElem < 2) {
// We know that candidate stores are in order and of correct
// shape. While there is no mergeable sequence from the
// beginning one may start later in the sequence. The only
// reason a merge of size N could have failed where another of
// the same size would not have is if the alignment or either
// the load or store has improved. Drop as many candidates as we
// can here.
unsigned NumSkip = 1;
while ((NumSkip < LoadNodes.size()) &&
(LoadNodes[NumSkip].MemNode->getAlign() <= FirstLoadAlign) &&
(StoreNodes[NumSkip].MemNode->getAlign() <= FirstStoreAlign))
NumSkip++;
StoreNodes.erase(StoreNodes.begin(), StoreNodes.begin() + NumSkip);
LoadNodes.erase(LoadNodes.begin(), LoadNodes.begin() + NumSkip);
NumConsecutiveStores -= NumSkip;
continue;
}
// Check that we can merge these candidates without causing a cycle.
if (!checkMergeStoreCandidatesForDependencies(StoreNodes, NumElem,
RootNode)) {
StoreNodes.erase(StoreNodes.begin(), StoreNodes.begin() + NumElem);
LoadNodes.erase(LoadNodes.begin(), LoadNodes.begin() + NumElem);
NumConsecutiveStores -= NumElem;
continue;
}
// Find if it is better to use vectors or integers to load and store
// to memory.
EVT JointMemOpVT;
if (UseVectorTy) {
// Find a legal type for the vector store.
unsigned Elts = NumElem * NumMemElts;
JointMemOpVT = EVT::getVectorVT(Context, MemVT.getScalarType(), Elts);
} else {
unsigned SizeInBits = NumElem * ElementSizeBytes * 8;
JointMemOpVT = EVT::getIntegerVT(Context, SizeInBits);
}
SDLoc LoadDL(LoadNodes[0].MemNode);
SDLoc StoreDL(StoreNodes[0].MemNode);
// The merged loads are required to have the same incoming chain, so
// using the first's chain is acceptable.
SDValue NewStoreChain = getMergeStoreChains(StoreNodes, NumElem);
AddToWorklist(NewStoreChain.getNode());
MachineMemOperand::Flags LdMMOFlags =
isDereferenceable ? MachineMemOperand::MODereferenceable
: MachineMemOperand::MONone;
if (IsNonTemporalLoad)
LdMMOFlags |= MachineMemOperand::MONonTemporal;
MachineMemOperand::Flags StMMOFlags = IsNonTemporalStore
? MachineMemOperand::MONonTemporal
: MachineMemOperand::MONone;
SDValue NewLoad, NewStore;
if (UseVectorTy || !DoIntegerTruncate) {
NewLoad = DAG.getLoad(
JointMemOpVT, LoadDL, FirstLoad->getChain(), FirstLoad->getBasePtr(),
FirstLoad->getPointerInfo(), FirstLoadAlign, LdMMOFlags);
SDValue StoreOp = NewLoad;
if (NeedRotate) {
unsigned LoadWidth = ElementSizeBytes * 8 * 2;
assert(JointMemOpVT == EVT::getIntegerVT(Context, LoadWidth) &&
"Unexpected type for rotate-able load pair");
SDValue RotAmt =
DAG.getShiftAmountConstant(LoadWidth / 2, JointMemOpVT, LoadDL);
// Target can convert to the identical ROTR if it does not have ROTL.
StoreOp = DAG.getNode(ISD::ROTL, LoadDL, JointMemOpVT, NewLoad, RotAmt);
}
NewStore = DAG.getStore(
NewStoreChain, StoreDL, StoreOp, FirstInChain->getBasePtr(),
FirstInChain->getPointerInfo(), FirstStoreAlign, StMMOFlags);
} else { // This must be the truncstore/extload case
EVT ExtendedTy =
TLI.getTypeToTransformTo(*DAG.getContext(), JointMemOpVT);
NewLoad = DAG.getExtLoad(ISD::EXTLOAD, LoadDL, ExtendedTy,
FirstLoad->getChain(), FirstLoad->getBasePtr(),
FirstLoad->getPointerInfo(), JointMemOpVT,
FirstLoadAlign, LdMMOFlags);
NewStore = DAG.getTruncStore(
NewStoreChain, StoreDL, NewLoad, FirstInChain->getBasePtr(),
FirstInChain->getPointerInfo(), JointMemOpVT,
FirstInChain->getAlign(), FirstInChain->getMemOperand()->getFlags());
}
// Transfer chain users from old loads to the new load.
for (unsigned i = 0; i < NumElem; ++i) {
LoadSDNode *Ld = cast<LoadSDNode>(LoadNodes[i].MemNode);
DAG.ReplaceAllUsesOfValueWith(SDValue(Ld, 1),
SDValue(NewLoad.getNode(), 1));
}
// Replace all stores with the new store. Recursively remove corresponding
// values if they are no longer used.
for (unsigned i = 0; i < NumElem; ++i) {
SDValue Val = StoreNodes[i].MemNode->getOperand(1);
CombineTo(StoreNodes[i].MemNode, NewStore);
if (Val->use_empty())
recursivelyDeleteUnusedNodes(Val.getNode());
}
MadeChange = true;
StoreNodes.erase(StoreNodes.begin(), StoreNodes.begin() + NumElem);
LoadNodes.erase(LoadNodes.begin(), LoadNodes.begin() + NumElem);
NumConsecutiveStores -= NumElem;
}
return MadeChange;
}
bool DAGCombiner::mergeConsecutiveStores(StoreSDNode *St) {
if (OptLevel == CodeGenOpt::None || !EnableStoreMerging)
return false;
// TODO: Extend this function to merge stores of scalable vectors.
// (i.e. two <vscale x 8 x i8> stores can be merged to one <vscale x 16 x i8>
// store since we know <vscale x 16 x i8> is exactly twice as large as
// <vscale x 8 x i8>). Until then, bail out for scalable vectors.
EVT MemVT = St->getMemoryVT();
if (MemVT.isScalableVector())
return false;
if (!MemVT.isSimple() || MemVT.getSizeInBits() * 2 > MaximumLegalStoreInBits)
return false;
// This function cannot currently deal with non-byte-sized memory sizes.
int64_t ElementSizeBytes = MemVT.getStoreSize();
if (ElementSizeBytes * 8 != (int64_t)MemVT.getSizeInBits())
return false;
// Do not bother looking at stored values that are not constants, loads, or
// extracted vector elements.
SDValue StoredVal = peekThroughBitcasts(St->getValue());
const StoreSource StoreSrc = getStoreSource(StoredVal);
if (StoreSrc == StoreSource::Unknown)
return false;
SmallVector<MemOpLink, 8> StoreNodes;
SDNode *RootNode;
// Find potential store merge candidates by searching through chain sub-DAG
getStoreMergeCandidates(St, StoreNodes, RootNode);
// Check if there is anything to merge.
if (StoreNodes.size() < 2)
return false;
// Sort the memory operands according to their distance from the
// base pointer.
llvm::sort(StoreNodes, [](MemOpLink LHS, MemOpLink RHS) {
return LHS.OffsetFromBase < RHS.OffsetFromBase;
});
bool AllowVectors = !DAG.getMachineFunction().getFunction().hasFnAttribute(
Attribute::NoImplicitFloat);
bool IsNonTemporalStore = St->isNonTemporal();
bool IsNonTemporalLoad = StoreSrc == StoreSource::Load &&
cast<LoadSDNode>(StoredVal)->isNonTemporal();
// Store Merge attempts to merge the lowest stores. This generally
// works out as if successful, as the remaining stores are checked
// after the first collection of stores is merged. However, in the
// case that a non-mergeable store is found first, e.g., {p[-2],
// p[0], p[1], p[2], p[3]}, we would fail and miss the subsequent
// mergeable cases. To prevent this, we prune such stores from the
// front of StoreNodes here.
bool MadeChange = false;
while (StoreNodes.size() > 1) {
unsigned NumConsecutiveStores =
getConsecutiveStores(StoreNodes, ElementSizeBytes);
// There are no more stores in the list to examine.
if (NumConsecutiveStores == 0)
return MadeChange;
// We have at least 2 consecutive stores. Try to merge them.
assert(NumConsecutiveStores >= 2 && "Expected at least 2 stores");
switch (StoreSrc) {
case StoreSource::Constant:
MadeChange |= tryStoreMergeOfConstants(StoreNodes, NumConsecutiveStores,
MemVT, RootNode, AllowVectors);
break;
case StoreSource::Extract:
MadeChange |= tryStoreMergeOfExtracts(StoreNodes, NumConsecutiveStores,
MemVT, RootNode);
break;
case StoreSource::Load:
MadeChange |= tryStoreMergeOfLoads(StoreNodes, NumConsecutiveStores,
MemVT, RootNode, AllowVectors,
IsNonTemporalStore, IsNonTemporalLoad);
break;
default:
llvm_unreachable("Unhandled store source type");
}
}
return MadeChange;
}
SDValue DAGCombiner::replaceStoreChain(StoreSDNode *ST, SDValue BetterChain) {
SDLoc SL(ST);
SDValue ReplStore;
// Replace the chain to avoid dependency.
if (ST->isTruncatingStore()) {
ReplStore = DAG.getTruncStore(BetterChain, SL, ST->getValue(),
ST->getBasePtr(), ST->getMemoryVT(),
ST->getMemOperand());
} else {
ReplStore = DAG.getStore(BetterChain, SL, ST->getValue(), ST->getBasePtr(),
ST->getMemOperand());
}
// Create token to keep both nodes around.
SDValue Token = DAG.getNode(ISD::TokenFactor, SL,
MVT::Other, ST->getChain(), ReplStore);
// Make sure the new and old chains are cleaned up.
AddToWorklist(Token.getNode());
// Don't add users to work list.
return CombineTo(ST, Token, false);
}
SDValue DAGCombiner::replaceStoreOfFPConstant(StoreSDNode *ST) {
SDValue Value = ST->getValue();
if (Value.getOpcode() == ISD::TargetConstantFP)
return SDValue();
if (!ISD::isNormalStore(ST))
return SDValue();
SDLoc DL(ST);
SDValue Chain = ST->getChain();
SDValue Ptr = ST->getBasePtr();
const ConstantFPSDNode *CFP = cast<ConstantFPSDNode>(Value);
// NOTE: If the original store is volatile, this transform must not increase
// the number of stores. For example, on x86-32 an f64 can be stored in one
// processor operation but an i64 (which is not legal) requires two. So the
// transform should not be done in this case.
SDValue Tmp;
switch (CFP->getSimpleValueType(0).SimpleTy) {
default:
llvm_unreachable("Unknown FP type");
case MVT::f16: // We don't do this for these yet.
case MVT::bf16:
case MVT::f80:
case MVT::f128:
case MVT::ppcf128:
return SDValue();
case MVT::f32:
if ((isTypeLegal(MVT::i32) && !LegalOperations && ST->isSimple()) ||
TLI.isOperationLegalOrCustom(ISD::STORE, MVT::i32)) {
Tmp = DAG.getConstant((uint32_t)CFP->getValueAPF().
bitcastToAPInt().getZExtValue(), SDLoc(CFP),
MVT::i32);
return DAG.getStore(Chain, DL, Tmp, Ptr, ST->getMemOperand());
}
return SDValue();
case MVT::f64:
if ((TLI.isTypeLegal(MVT::i64) && !LegalOperations &&
ST->isSimple()) ||
TLI.isOperationLegalOrCustom(ISD::STORE, MVT::i64)) {
Tmp = DAG.getConstant(CFP->getValueAPF().bitcastToAPInt().
getZExtValue(), SDLoc(CFP), MVT::i64);
return DAG.getStore(Chain, DL, Tmp,
Ptr, ST->getMemOperand());
}
if (ST->isSimple() &&
TLI.isOperationLegalOrCustom(ISD::STORE, MVT::i32)) {
// Many FP stores are not made apparent until after legalize, e.g. for
// argument passing. Since this is so common, custom legalize the
// 64-bit integer store into two 32-bit stores.
uint64_t Val = CFP->getValueAPF().bitcastToAPInt().getZExtValue();
SDValue Lo = DAG.getConstant(Val & 0xFFFFFFFF, SDLoc(CFP), MVT::i32);
SDValue Hi = DAG.getConstant(Val >> 32, SDLoc(CFP), MVT::i32);
if (DAG.getDataLayout().isBigEndian())
std::swap(Lo, Hi);
MachineMemOperand::Flags MMOFlags = ST->getMemOperand()->getFlags();
AAMDNodes AAInfo = ST->getAAInfo();
SDValue St0 = DAG.getStore(Chain, DL, Lo, Ptr, ST->getPointerInfo(),
ST->getOriginalAlign(), MMOFlags, AAInfo);
Ptr = DAG.getMemBasePlusOffset(Ptr, TypeSize::Fixed(4), DL);
SDValue St1 = DAG.getStore(Chain, DL, Hi, Ptr,
ST->getPointerInfo().getWithOffset(4),
ST->getOriginalAlign(), MMOFlags, AAInfo);
return DAG.getNode(ISD::TokenFactor, DL, MVT::Other,
St0, St1);
}
return SDValue();
}
}
SDValue DAGCombiner::visitSTORE(SDNode *N) {
StoreSDNode *ST = cast<StoreSDNode>(N);
SDValue Chain = ST->getChain();
SDValue Value = ST->getValue();
SDValue Ptr = ST->getBasePtr();
// If this is a store of a bit convert, store the input value if the
// resultant store does not need a higher alignment than the original.
if (Value.getOpcode() == ISD::BITCAST && !ST->isTruncatingStore() &&
ST->isUnindexed()) {
EVT SVT = Value.getOperand(0).getValueType();
// If the store is volatile, we only want to change the store type if the
// resulting store is legal. Otherwise we might increase the number of
// memory accesses. We don't care if the original type was legal or not
// as we assume software couldn't rely on the number of accesses of an
// illegal type.
// TODO: May be able to relax for unordered atomics (see D66309)
if (((!LegalOperations && ST->isSimple()) ||
TLI.isOperationLegal(ISD::STORE, SVT)) &&
TLI.isStoreBitCastBeneficial(Value.getValueType(), SVT,
DAG, *ST->getMemOperand())) {
return DAG.getStore(Chain, SDLoc(N), Value.getOperand(0), Ptr,
ST->getMemOperand());
}
}
// Turn 'store undef, Ptr' -> nothing.
if (Value.isUndef() && ST->isUnindexed())
return Chain;
// Try to infer better alignment information than the store already has.
if (OptLevel != CodeGenOpt::None && ST->isUnindexed() && !ST->isAtomic()) {
if (MaybeAlign Alignment = DAG.InferPtrAlign(Ptr)) {
if (*Alignment > ST->getAlign() &&
isAligned(*Alignment, ST->getSrcValueOffset())) {
SDValue NewStore =
DAG.getTruncStore(Chain, SDLoc(N), Value, Ptr, ST->getPointerInfo(),
ST->getMemoryVT(), *Alignment,
ST->getMemOperand()->getFlags(), ST->getAAInfo());
// NewStore will always be N as we are only refining the alignment
assert(NewStore.getNode() == N);
(void)NewStore;
}
}
}
// Try transforming a pair floating point load / store ops to integer
// load / store ops.
if (SDValue NewST = TransformFPLoadStorePair(N))
return NewST;
// Try transforming several stores into STORE (BSWAP).
if (SDValue Store = mergeTruncStores(ST))
return Store;
if (ST->isUnindexed()) {
// Walk up chain skipping non-aliasing memory nodes, on this store and any
// adjacent stores.
if (findBetterNeighborChains(ST)) {
// replaceStoreChain uses CombineTo, which handled all of the worklist
// manipulation. Return the original node to not do anything else.
return SDValue(ST, 0);
}
Chain = ST->getChain();
}
// FIXME: is there such a thing as a truncating indexed store?
if (ST->isTruncatingStore() && ST->isUnindexed() &&
Value.getValueType().isInteger() &&
(!isa<ConstantSDNode>(Value) ||
!cast<ConstantSDNode>(Value)->isOpaque())) {
// Convert a truncating store of a extension into a standard store.
if ((Value.getOpcode() == ISD::ZERO_EXTEND ||
Value.getOpcode() == ISD::SIGN_EXTEND ||
Value.getOpcode() == ISD::ANY_EXTEND) &&
Value.getOperand(0).getValueType() == ST->getMemoryVT() &&
TLI.isOperationLegalOrCustom(ISD::STORE, ST->getMemoryVT()))
return DAG.getStore(Chain, SDLoc(N), Value.getOperand(0), Ptr,
ST->getMemOperand());
APInt TruncDemandedBits =
APInt::getLowBitsSet(Value.getScalarValueSizeInBits(),
ST->getMemoryVT().getScalarSizeInBits());
// See if we can simplify the input to this truncstore with knowledge that
// only the low bits are being used. For example:
// "truncstore (or (shl x, 8), y), i8" -> "truncstore y, i8"
AddToWorklist(Value.getNode());
if (SDValue Shorter = DAG.GetDemandedBits(Value, TruncDemandedBits))
return DAG.getTruncStore(Chain, SDLoc(N), Shorter, Ptr, ST->getMemoryVT(),
ST->getMemOperand());
// Otherwise, see if we can simplify the operation with
// SimplifyDemandedBits, which only works if the value has a single use.
if (SimplifyDemandedBits(Value, TruncDemandedBits)) {
// Re-visit the store if anything changed and the store hasn't been merged
// with another node (N is deleted) SimplifyDemandedBits will add Value's
// node back to the worklist if necessary, but we also need to re-visit
// the Store node itself.
if (N->getOpcode() != ISD::DELETED_NODE)
AddToWorklist(N);
return SDValue(N, 0);
}
}
// If this is a load followed by a store to the same location, then the store
// is dead/noop.
// TODO: Can relax for unordered atomics (see D66309)
if (LoadSDNode *Ld = dyn_cast<LoadSDNode>(Value)) {
if (Ld->getBasePtr() == Ptr && ST->getMemoryVT() == Ld->getMemoryVT() &&
ST->isUnindexed() && ST->isSimple() &&
Ld->getAddressSpace() == ST->getAddressSpace() &&
// There can't be any side effects between the load and store, such as
// a call or store.
Chain.reachesChainWithoutSideEffects(SDValue(Ld, 1))) {
// The store is dead, remove it.
return Chain;
}
}
// TODO: Can relax for unordered atomics (see D66309)
if (StoreSDNode *ST1 = dyn_cast<StoreSDNode>(Chain)) {
if (ST->isUnindexed() && ST->isSimple() &&
ST1->isUnindexed() && ST1->isSimple()) {
if (OptLevel != CodeGenOpt::None && ST1->getBasePtr() == Ptr &&
ST1->getValue() == Value && ST->getMemoryVT() == ST1->getMemoryVT() &&
ST->getAddressSpace() == ST1->getAddressSpace()) {
// If this is a store followed by a store with the same value to the
// same location, then the store is dead/noop.
return Chain;
}
if (OptLevel != CodeGenOpt::None && ST1->hasOneUse() &&
!ST1->getBasePtr().isUndef() &&
// BaseIndexOffset and the code below requires knowing the size
// of a vector, so bail out if MemoryVT is scalable.
!ST->getMemoryVT().isScalableVector() &&
!ST1->getMemoryVT().isScalableVector() &&
ST->getAddressSpace() == ST1->getAddressSpace()) {
const BaseIndexOffset STBase = BaseIndexOffset::match(ST, DAG);
const BaseIndexOffset ChainBase = BaseIndexOffset::match(ST1, DAG);
unsigned STBitSize = ST->getMemoryVT().getFixedSizeInBits();
unsigned ChainBitSize = ST1->getMemoryVT().getFixedSizeInBits();
// If this is a store who's preceding store to a subset of the current
// location and no one other node is chained to that store we can
// effectively drop the store. Do not remove stores to undef as they may
// be used as data sinks.
if (STBase.contains(DAG, STBitSize, ChainBase, ChainBitSize)) {
CombineTo(ST1, ST1->getChain());
return SDValue();
}
}
}
}
// If this is an FP_ROUND or TRUNC followed by a store, fold this into a
// truncating store. We can do this even if this is already a truncstore.
if ((Value.getOpcode() == ISD::FP_ROUND ||
Value.getOpcode() == ISD::TRUNCATE) &&
Value->hasOneUse() && ST->isUnindexed() &&
TLI.canCombineTruncStore(Value.getOperand(0).getValueType(),
ST->getMemoryVT(), LegalOperations)) {
return DAG.getTruncStore(Chain, SDLoc(N), Value.getOperand(0),
Ptr, ST->getMemoryVT(), ST->getMemOperand());
}
// Always perform this optimization before types are legal. If the target
// prefers, also try this after legalization to catch stores that were created
// by intrinsics or other nodes.
if (!LegalTypes || (TLI.mergeStoresAfterLegalization(ST->getMemoryVT()))) {
while (true) {
// There can be multiple store sequences on the same chain.
// Keep trying to merge store sequences until we are unable to do so
// or until we merge the last store on the chain.
bool Changed = mergeConsecutiveStores(ST);
if (!Changed) break;
// Return N as merge only uses CombineTo and no worklist clean
// up is necessary.
if (N->getOpcode() == ISD::DELETED_NODE || !isa<StoreSDNode>(N))
return SDValue(N, 0);
}
}
// Try transforming N to an indexed store.
if (CombineToPreIndexedLoadStore(N) || CombineToPostIndexedLoadStore(N))
return SDValue(N, 0);
// Turn 'store float 1.0, Ptr' -> 'store int 0x12345678, Ptr'
//
// Make sure to do this only after attempting to merge stores in order to
// avoid changing the types of some subset of stores due to visit order,
// preventing their merging.
if (isa<ConstantFPSDNode>(ST->getValue())) {
if (SDValue NewSt = replaceStoreOfFPConstant(ST))
return NewSt;
}
if (SDValue NewSt = splitMergedValStore(ST))
return NewSt;
return ReduceLoadOpStoreWidth(N);
}
SDValue DAGCombiner::visitLIFETIME_END(SDNode *N) {
const auto *LifetimeEnd = cast<LifetimeSDNode>(N);
if (!LifetimeEnd->hasOffset())
return SDValue();
const BaseIndexOffset LifetimeEndBase(N->getOperand(1), SDValue(),
LifetimeEnd->getOffset(), false);
// We walk up the chains to find stores.
SmallVector<SDValue, 8> Chains = {N->getOperand(0)};
while (!Chains.empty()) {
SDValue Chain = Chains.pop_back_val();
if (!Chain.hasOneUse())
continue;
switch (Chain.getOpcode()) {
case ISD::TokenFactor:
for (unsigned Nops = Chain.getNumOperands(); Nops;)
Chains.push_back(Chain.getOperand(--Nops));
break;
case ISD::LIFETIME_START:
case ISD::LIFETIME_END:
// We can forward past any lifetime start/end that can be proven not to
// alias the node.
if (!mayAlias(Chain.getNode(), N))
Chains.push_back(Chain.getOperand(0));
break;
case ISD::STORE: {
StoreSDNode *ST = dyn_cast<StoreSDNode>(Chain);
// TODO: Can relax for unordered atomics (see D66309)
if (!ST->isSimple() || ST->isIndexed())
continue;
const TypeSize StoreSize = ST->getMemoryVT().getStoreSize();
// The bounds of a scalable store are not known until runtime, so this
// store cannot be elided.
if (StoreSize.isScalable())
continue;
const BaseIndexOffset StoreBase = BaseIndexOffset::match(ST, DAG);
// If we store purely within object bounds just before its lifetime ends,
// we can remove the store.
if (LifetimeEndBase.contains(DAG, LifetimeEnd->getSize() * 8, StoreBase,
StoreSize.getFixedSize() * 8)) {
LLVM_DEBUG(dbgs() << "\nRemoving store:"; StoreBase.dump();
dbgs() << "\nwithin LIFETIME_END of : ";
LifetimeEndBase.dump(); dbgs() << "\n");
CombineTo(ST, ST->getChain());
return SDValue(N, 0);
}
}
}
}
return SDValue();
}
/// For the instruction sequence of store below, F and I values
/// are bundled together as an i64 value before being stored into memory.
/// Sometimes it is more efficent to generate separate stores for F and I,
/// which can remove the bitwise instructions or sink them to colder places.
///
/// (store (or (zext (bitcast F to i32) to i64),
/// (shl (zext I to i64), 32)), addr) -->
/// (store F, addr) and (store I, addr+4)
///
/// Similarly, splitting for other merged store can also be beneficial, like:
/// For pair of {i32, i32}, i64 store --> two i32 stores.
/// For pair of {i32, i16}, i64 store --> two i32 stores.
/// For pair of {i16, i16}, i32 store --> two i16 stores.
/// For pair of {i16, i8}, i32 store --> two i16 stores.
/// For pair of {i8, i8}, i16 store --> two i8 stores.
///
/// We allow each target to determine specifically which kind of splitting is
/// supported.
///
/// The store patterns are commonly seen from the simple code snippet below
/// if only std::make_pair(...) is sroa transformed before inlined into hoo.
/// void goo(const std::pair<int, float> &);
/// hoo() {
/// ...
/// goo(std::make_pair(tmp, ftmp));
/// ...
/// }
///
SDValue DAGCombiner::splitMergedValStore(StoreSDNode *ST) {
if (OptLevel == CodeGenOpt::None)
return SDValue();
// Can't change the number of memory accesses for a volatile store or break
// atomicity for an atomic one.
if (!ST->isSimple())
return SDValue();
SDValue Val = ST->getValue();
SDLoc DL(ST);
// Match OR operand.
if (!Val.getValueType().isScalarInteger() || Val.getOpcode() != ISD::OR)
return SDValue();
// Match SHL operand and get Lower and Higher parts of Val.
SDValue Op1 = Val.getOperand(0);
SDValue Op2 = Val.getOperand(1);
SDValue Lo, Hi;
if (Op1.getOpcode() != ISD::SHL) {
std::swap(Op1, Op2);
if (Op1.getOpcode() != ISD::SHL)
return SDValue();
}
Lo = Op2;
Hi = Op1.getOperand(0);
if (!Op1.hasOneUse())
return SDValue();
// Match shift amount to HalfValBitSize.
unsigned HalfValBitSize = Val.getValueSizeInBits() / 2;
ConstantSDNode *ShAmt = dyn_cast<ConstantSDNode>(Op1.getOperand(1));
if (!ShAmt || ShAmt->getAPIntValue() != HalfValBitSize)
return SDValue();
// Lo and Hi are zero-extended from int with size less equal than 32
// to i64.
if (Lo.getOpcode() != ISD::ZERO_EXTEND || !Lo.hasOneUse() ||
!Lo.getOperand(0).getValueType().isScalarInteger() ||
Lo.getOperand(0).getValueSizeInBits() > HalfValBitSize ||
Hi.getOpcode() != ISD::ZERO_EXTEND || !Hi.hasOneUse() ||
!Hi.getOperand(0).getValueType().isScalarInteger() ||
Hi.getOperand(0).getValueSizeInBits() > HalfValBitSize)
return SDValue();
// Use the EVT of low and high parts before bitcast as the input
// of target query.
EVT LowTy = (Lo.getOperand(0).getOpcode() == ISD::BITCAST)
? Lo.getOperand(0).getValueType()
: Lo.getValueType();
EVT HighTy = (Hi.getOperand(0).getOpcode() == ISD::BITCAST)
? Hi.getOperand(0).getValueType()
: Hi.getValueType();
if (!TLI.isMultiStoresCheaperThanBitsMerge(LowTy, HighTy))
return SDValue();
// Start to split store.
MachineMemOperand::Flags MMOFlags = ST->getMemOperand()->getFlags();
AAMDNodes AAInfo = ST->getAAInfo();
// Change the sizes of Lo and Hi's value types to HalfValBitSize.
EVT VT = EVT::getIntegerVT(*DAG.getContext(), HalfValBitSize);
Lo = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, Lo.getOperand(0));
Hi = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, Hi.getOperand(0));
SDValue Chain = ST->getChain();
SDValue Ptr = ST->getBasePtr();
// Lower value store.
SDValue St0 = DAG.getStore(Chain, DL, Lo, Ptr, ST->getPointerInfo(),
ST->getOriginalAlign(), MMOFlags, AAInfo);
Ptr = DAG.getMemBasePlusOffset(Ptr, TypeSize::Fixed(HalfValBitSize / 8), DL);
// Higher value store.
SDValue St1 = DAG.getStore(
St0, DL, Hi, Ptr, ST->getPointerInfo().getWithOffset(HalfValBitSize / 8),
ST->getOriginalAlign(), MMOFlags, AAInfo);
return St1;
}
/// Convert a disguised subvector insertion into a shuffle:
SDValue DAGCombiner::combineInsertEltToShuffle(SDNode *N, unsigned InsIndex) {
assert(N->getOpcode() == ISD::INSERT_VECTOR_ELT &&
"Expected extract_vector_elt");
SDValue InsertVal = N->getOperand(1);
SDValue Vec = N->getOperand(0);
// (insert_vector_elt (vector_shuffle X, Y), (extract_vector_elt X, N),
// InsIndex)
// --> (vector_shuffle X, Y) and variations where shuffle operands may be
// CONCAT_VECTORS.
if (Vec.getOpcode() == ISD::VECTOR_SHUFFLE && Vec.hasOneUse() &&
InsertVal.getOpcode() == ISD::EXTRACT_VECTOR_ELT &&
isa<ConstantSDNode>(InsertVal.getOperand(1))) {
ShuffleVectorSDNode *SVN = cast<ShuffleVectorSDNode>(Vec.getNode());
ArrayRef<int> Mask = SVN->getMask();
SDValue X = Vec.getOperand(0);
SDValue Y = Vec.getOperand(1);
// Vec's operand 0 is using indices from 0 to N-1 and
// operand 1 from N to 2N - 1, where N is the number of
// elements in the vectors.
SDValue InsertVal0 = InsertVal.getOperand(0);
int ElementOffset = -1;
// We explore the inputs of the shuffle in order to see if we find the
// source of the extract_vector_elt. If so, we can use it to modify the
// shuffle rather than perform an insert_vector_elt.
SmallVector<std::pair<int, SDValue>, 8> ArgWorkList;
ArgWorkList.emplace_back(Mask.size(), Y);
ArgWorkList.emplace_back(0, X);
while (!ArgWorkList.empty()) {
int ArgOffset;
SDValue ArgVal;
std::tie(ArgOffset, ArgVal) = ArgWorkList.pop_back_val();
if (ArgVal == InsertVal0) {
ElementOffset = ArgOffset;
break;
}
// Peek through concat_vector.
if (ArgVal.getOpcode() == ISD::CONCAT_VECTORS) {
int CurrentArgOffset =
ArgOffset + ArgVal.getValueType().getVectorNumElements();
int Step = ArgVal.getOperand(0).getValueType().getVectorNumElements();
for (SDValue Op : reverse(ArgVal->ops())) {
CurrentArgOffset -= Step;
ArgWorkList.emplace_back(CurrentArgOffset, Op);
}
// Make sure we went through all the elements and did not screw up index
// computation.
assert(CurrentArgOffset == ArgOffset);
}
}
// If we failed to find a match, see if we can replace an UNDEF shuffle
// operand.
if (ElementOffset == -1 && Y.isUndef() &&
InsertVal0.getValueType() == Y.getValueType()) {
ElementOffset = Mask.size();
Y = InsertVal0;
}
if (ElementOffset != -1) {
SmallVector<int, 16> NewMask(Mask.begin(), Mask.end());
auto *ExtrIndex = cast<ConstantSDNode>(InsertVal.getOperand(1));
NewMask[InsIndex] = ElementOffset + ExtrIndex->getZExtValue();
assert(NewMask[InsIndex] <
(int)(2 * Vec.getValueType().getVectorNumElements()) &&
NewMask[InsIndex] >= 0 && "NewMask[InsIndex] is out of bound");
SDValue LegalShuffle =
TLI.buildLegalVectorShuffle(Vec.getValueType(), SDLoc(N), X,
Y, NewMask, DAG);
if (LegalShuffle)
return LegalShuffle;
}
}
// insert_vector_elt V, (bitcast X from vector type), IdxC -->
// bitcast(shuffle (bitcast V), (extended X), Mask)
// Note: We do not use an insert_subvector node because that requires a
// legal subvector type.
if (InsertVal.getOpcode() != ISD::BITCAST || !InsertVal.hasOneUse() ||
!InsertVal.getOperand(0).getValueType().isVector())
return SDValue();
SDValue SubVec = InsertVal.getOperand(0);
SDValue DestVec = N->getOperand(0);
EVT SubVecVT = SubVec.getValueType();
EVT VT = DestVec.getValueType();
unsigned NumSrcElts = SubVecVT.getVectorNumElements();
// If the source only has a single vector element, the cost of creating adding
// it to a vector is likely to exceed the cost of a insert_vector_elt.
if (NumSrcElts == 1)
return SDValue();
unsigned ExtendRatio = VT.getSizeInBits() / SubVecVT.getSizeInBits();
unsigned NumMaskVals = ExtendRatio * NumSrcElts;
// Step 1: Create a shuffle mask that implements this insert operation. The
// vector that we are inserting into will be operand 0 of the shuffle, so
// those elements are just 'i'. The inserted subvector is in the first
// positions of operand 1 of the shuffle. Example:
// insert v4i32 V, (v2i16 X), 2 --> shuffle v8i16 V', X', {0,1,2,3,8,9,6,7}
SmallVector<int, 16> Mask(NumMaskVals);
for (unsigned i = 0; i != NumMaskVals; ++i) {
if (i / NumSrcElts == InsIndex)
Mask[i] = (i % NumSrcElts) + NumMaskVals;
else
Mask[i] = i;
}
// Bail out if the target can not handle the shuffle we want to create.
EVT SubVecEltVT = SubVecVT.getVectorElementType();
EVT ShufVT = EVT::getVectorVT(*DAG.getContext(), SubVecEltVT, NumMaskVals);
if (!TLI.isShuffleMaskLegal(Mask, ShufVT))
return SDValue();
// Step 2: Create a wide vector from the inserted source vector by appending
// undefined elements. This is the same size as our destination vector.
SDLoc DL(N);
SmallVector<SDValue, 8> ConcatOps(ExtendRatio, DAG.getUNDEF(SubVecVT));
ConcatOps[0] = SubVec;
SDValue PaddedSubV = DAG.getNode(ISD::CONCAT_VECTORS, DL, ShufVT, ConcatOps);
// Step 3: Shuffle in the padded subvector.
SDValue DestVecBC = DAG.getBitcast(ShufVT, DestVec);
SDValue Shuf = DAG.getVectorShuffle(ShufVT, DL, DestVecBC, PaddedSubV, Mask);
AddToWorklist(PaddedSubV.getNode());
AddToWorklist(DestVecBC.getNode());
AddToWorklist(Shuf.getNode());
return DAG.getBitcast(VT, Shuf);
}
SDValue DAGCombiner::visitINSERT_VECTOR_ELT(SDNode *N) {
SDValue InVec = N->getOperand(0);
SDValue InVal = N->getOperand(1);
SDValue EltNo = N->getOperand(2);
SDLoc DL(N);
EVT VT = InVec.getValueType();
auto *IndexC = dyn_cast<ConstantSDNode>(EltNo);
// Insert into out-of-bounds element is undefined.
if (IndexC && VT.isFixedLengthVector() &&
IndexC->getZExtValue() >= VT.getVectorNumElements())
return DAG.getUNDEF(VT);
// Remove redundant insertions:
// (insert_vector_elt x (extract_vector_elt x idx) idx) -> x
if (InVal.getOpcode() == ISD::EXTRACT_VECTOR_ELT &&
InVec == InVal.getOperand(0) && EltNo == InVal.getOperand(1))
return InVec;
if (!IndexC) {
// If this is variable insert to undef vector, it might be better to splat:
// inselt undef, InVal, EltNo --> build_vector < InVal, InVal, ... >
if (InVec.isUndef() && TLI.shouldSplatInsEltVarIndex(VT)) {
if (VT.isScalableVector())
return DAG.getSplatVector(VT, DL, InVal);
SmallVector<SDValue, 8> Ops(VT.getVectorNumElements(), InVal);
return DAG.getBuildVector(VT, DL, Ops);
}
return SDValue();
}
if (VT.isScalableVector())
return SDValue();
unsigned NumElts = VT.getVectorNumElements();
// We must know which element is being inserted for folds below here.
unsigned Elt = IndexC->getZExtValue();
if (SDValue Shuf = combineInsertEltToShuffle(N, Elt))
return Shuf;
// Handle <1 x ???> vector insertion special cases.
if (VT.getVectorNumElements() == 1) {
// insert_vector_elt(x, extract_vector_elt(y, 0), 0) -> y
if (InVal.getOpcode() == ISD::EXTRACT_VECTOR_ELT &&
InVal.getOperand(0).getValueType() == VT &&
isNullConstant(InVal.getOperand(1)))
return InVal.getOperand(0);
}
// Canonicalize insert_vector_elt dag nodes.
// Example:
// (insert_vector_elt (insert_vector_elt A, Idx0), Idx1)
// -> (insert_vector_elt (insert_vector_elt A, Idx1), Idx0)
//
// Do this only if the child insert_vector node has one use; also
// do this only if indices are both constants and Idx1 < Idx0.
if (InVec.getOpcode() == ISD::INSERT_VECTOR_ELT && InVec.hasOneUse()
&& isa<ConstantSDNode>(InVec.getOperand(2))) {
unsigned OtherElt = InVec.getConstantOperandVal(2);
if (Elt < OtherElt) {
// Swap nodes.
SDValue NewOp = DAG.getNode(ISD::INSERT_VECTOR_ELT, DL, VT,
InVec.getOperand(0), InVal, EltNo);
AddToWorklist(NewOp.getNode());
return DAG.getNode(ISD::INSERT_VECTOR_ELT, SDLoc(InVec.getNode()),
VT, NewOp, InVec.getOperand(1), InVec.getOperand(2));
}
}
// Attempt to fold the insertion into a legal BUILD_VECTOR.
if (!LegalOperations || TLI.isOperationLegal(ISD::BUILD_VECTOR, VT)) {
auto UpdateBuildVector = [&](SmallVectorImpl<SDValue> &Ops) {
assert(Ops.size() == NumElts && "Unexpected vector size");
// Insert the element
if (Elt < Ops.size()) {
// All the operands of BUILD_VECTOR must have the same type;
// we enforce that here.
EVT OpVT = Ops[0].getValueType();
Ops[Elt] =
OpVT.isInteger() ? DAG.getAnyExtOrTrunc(InVal, DL, OpVT) : InVal;
}
// Return the new vector
return DAG.getBuildVector(VT, DL, Ops);
};
// Check that the operand is a BUILD_VECTOR (or UNDEF, which can essentially
// be converted to a BUILD_VECTOR). Fill in the Ops vector with the
// vector elements.
SmallVector<SDValue, 8> Ops;
// Do not combine these two vectors if the output vector will not replace
// the input vector.
if (InVec.getOpcode() == ISD::BUILD_VECTOR && InVec.hasOneUse()) {
Ops.append(InVec->op_begin(), InVec->op_end());
return UpdateBuildVector(Ops);
}
if (InVec.getOpcode() == ISD::SCALAR_TO_VECTOR && InVec.hasOneUse()) {
Ops.push_back(InVec.getOperand(0));
Ops.append(NumElts - 1, DAG.getUNDEF(InVec.getOperand(0).getValueType()));
return UpdateBuildVector(Ops);
}
if (InVec.isUndef()) {
Ops.append(NumElts, DAG.getUNDEF(InVal.getValueType()));
return UpdateBuildVector(Ops);
}
// If we're inserting into the end of a vector as part of an sequence, see
// if we can create a BUILD_VECTOR by following the sequence back up the
// chain.
if (Elt == (NumElts - 1)) {
SmallVector<SDValue> ReverseInsertions;
ReverseInsertions.push_back(InVal);
EVT MaxEltVT = InVal.getValueType();
SDValue CurVec = InVec;
for (unsigned I = 1; I != NumElts; ++I) {
if (CurVec.getOpcode() != ISD::INSERT_VECTOR_ELT || !CurVec.hasOneUse())
break;
auto *CurIdx = dyn_cast<ConstantSDNode>(CurVec.getOperand(2));
if (!CurIdx || CurIdx->getAPIntValue() != ((NumElts - 1) - I))
break;
SDValue CurVal = CurVec.getOperand(1);
ReverseInsertions.push_back(CurVal);
if (VT.isInteger()) {
EVT CurValVT = CurVal.getValueType();
MaxEltVT = MaxEltVT.bitsGE(CurValVT) ? MaxEltVT : CurValVT;
}
CurVec = CurVec.getOperand(0);
}
if (ReverseInsertions.size() == NumElts) {
for (unsigned I = 0; I != NumElts; ++I) {
SDValue Val = ReverseInsertions[(NumElts - 1) - I];
Val = VT.isInteger() ? DAG.getAnyExtOrTrunc(Val, DL, MaxEltVT) : Val;
Ops.push_back(Val);
}
return DAG.getBuildVector(VT, DL, Ops);
}
}
}
return SDValue();
}
SDValue DAGCombiner::scalarizeExtractedVectorLoad(SDNode *EVE, EVT InVecVT,
SDValue EltNo,
LoadSDNode *OriginalLoad) {
assert(OriginalLoad->isSimple());
EVT ResultVT = EVE->getValueType(0);
EVT VecEltVT = InVecVT.getVectorElementType();
// If the vector element type is not a multiple of a byte then we are unable
// to correctly compute an address to load only the extracted element as a
// scalar.
if (!VecEltVT.isByteSized())
return SDValue();
ISD::LoadExtType ExtTy =
ResultVT.bitsGT(VecEltVT) ? ISD::NON_EXTLOAD : ISD::EXTLOAD;
if (!TLI.isOperationLegalOrCustom(ISD::LOAD, VecEltVT) ||
!TLI.shouldReduceLoadWidth(OriginalLoad, ExtTy, VecEltVT))
return SDValue();
Align Alignment = OriginalLoad->getAlign();
MachinePointerInfo MPI;
SDLoc DL(EVE);
if (auto *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo)) {
int Elt = ConstEltNo->getZExtValue();
unsigned PtrOff = VecEltVT.getSizeInBits() * Elt / 8;
MPI = OriginalLoad->getPointerInfo().getWithOffset(PtrOff);
Alignment = commonAlignment(Alignment, PtrOff);
} else {
// Discard the pointer info except the address space because the memory
// operand can't represent this new access since the offset is variable.
MPI = MachinePointerInfo(OriginalLoad->getPointerInfo().getAddrSpace());
Alignment = commonAlignment(Alignment, VecEltVT.getSizeInBits() / 8);
}
bool IsFast = false;
if (!TLI.allowsMemoryAccess(*DAG.getContext(), DAG.getDataLayout(), VecEltVT,
OriginalLoad->getAddressSpace(), Alignment,
OriginalLoad->getMemOperand()->getFlags(),
&IsFast) ||
!IsFast)
return SDValue();
SDValue NewPtr = TLI.getVectorElementPointer(DAG, OriginalLoad->getBasePtr(),
InVecVT, EltNo);
// We are replacing a vector load with a scalar load. The new load must have
// identical memory op ordering to the original.
SDValue Load;
if (ResultVT.bitsGT(VecEltVT)) {
// If the result type of vextract is wider than the load, then issue an
// extending load instead.
ISD::LoadExtType ExtType =
TLI.isLoadExtLegal(ISD::ZEXTLOAD, ResultVT, VecEltVT) ? ISD::ZEXTLOAD
: ISD::EXTLOAD;
Load = DAG.getExtLoad(ExtType, DL, ResultVT, OriginalLoad->getChain(),
NewPtr, MPI, VecEltVT, Alignment,
OriginalLoad->getMemOperand()->getFlags(),
OriginalLoad->getAAInfo());
DAG.makeEquivalentMemoryOrdering(OriginalLoad, Load);
} else {
// The result type is narrower or the same width as the vector element
Load = DAG.getLoad(VecEltVT, DL, OriginalLoad->getChain(), NewPtr, MPI,
Alignment, OriginalLoad->getMemOperand()->getFlags(),
OriginalLoad->getAAInfo());
DAG.makeEquivalentMemoryOrdering(OriginalLoad, Load);
if (ResultVT.bitsLT(VecEltVT))
Load = DAG.getNode(ISD::TRUNCATE, DL, ResultVT, Load);
else
Load = DAG.getBitcast(ResultVT, Load);
}
++OpsNarrowed;
return Load;
}
/// Transform a vector binary operation into a scalar binary operation by moving
/// the math/logic after an extract element of a vector.
static SDValue scalarizeExtractedBinop(SDNode *ExtElt, SelectionDAG &DAG,
bool LegalOperations) {
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
SDValue Vec = ExtElt->getOperand(0);
SDValue Index = ExtElt->getOperand(1);
auto *IndexC = dyn_cast<ConstantSDNode>(Index);
if (!IndexC || !TLI.isBinOp(Vec.getOpcode()) || !Vec.hasOneUse() ||
Vec->getNumValues() != 1)
return SDValue();
// Targets may want to avoid this to prevent an expensive register transfer.
if (!TLI.shouldScalarizeBinop(Vec))
return SDValue();
// Extracting an element of a vector constant is constant-folded, so this
// transform is just replacing a vector op with a scalar op while moving the
// extract.
SDValue Op0 = Vec.getOperand(0);
SDValue Op1 = Vec.getOperand(1);
if (isAnyConstantBuildVector(Op0, true) ||
isAnyConstantBuildVector(Op1, true)) {
// extractelt (binop X, C), IndexC --> binop (extractelt X, IndexC), C'
// extractelt (binop C, X), IndexC --> binop C', (extractelt X, IndexC)
SDLoc DL(ExtElt);
EVT VT = ExtElt->getValueType(0);
SDValue Ext0 = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, VT, Op0, Index);
SDValue Ext1 = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, VT, Op1, Index);
return DAG.getNode(Vec.getOpcode(), DL, VT, Ext0, Ext1);
}
return SDValue();
}
SDValue DAGCombiner::visitEXTRACT_VECTOR_ELT(SDNode *N) {
SDValue VecOp = N->getOperand(0);
SDValue Index = N->getOperand(1);
EVT ScalarVT = N->getValueType(0);
EVT VecVT = VecOp.getValueType();
if (VecOp.isUndef())
return DAG.getUNDEF(ScalarVT);
// extract_vector_elt (insert_vector_elt vec, val, idx), idx) -> val
//
// This only really matters if the index is non-constant since other combines
// on the constant elements already work.
SDLoc DL(N);
if (VecOp.getOpcode() == ISD::INSERT_VECTOR_ELT &&
Index == VecOp.getOperand(2)) {
SDValue Elt = VecOp.getOperand(1);
return VecVT.isInteger() ? DAG.getAnyExtOrTrunc(Elt, DL, ScalarVT) : Elt;
}
// (vextract (scalar_to_vector val, 0) -> val
if (VecOp.getOpcode() == ISD::SCALAR_TO_VECTOR) {
// Only 0'th element of SCALAR_TO_VECTOR is defined.
if (DAG.isKnownNeverZero(Index))
return DAG.getUNDEF(ScalarVT);
// Check if the result type doesn't match the inserted element type. A
// SCALAR_TO_VECTOR may truncate the inserted element and the
// EXTRACT_VECTOR_ELT may widen the extracted vector.
SDValue InOp = VecOp.getOperand(0);
if (InOp.getValueType() != ScalarVT) {
assert(InOp.getValueType().isInteger() && ScalarVT.isInteger() &&
InOp.getValueType().bitsGT(ScalarVT));
return DAG.getNode(ISD::TRUNCATE, DL, ScalarVT, InOp);
}
return InOp;
}
// extract_vector_elt of out-of-bounds element -> UNDEF
auto *IndexC = dyn_cast<ConstantSDNode>(Index);
if (IndexC && VecVT.isFixedLengthVector() &&
IndexC->getAPIntValue().uge(VecVT.getVectorNumElements()))
return DAG.getUNDEF(ScalarVT);
// extract_vector_elt (build_vector x, y), 1 -> y
if (((IndexC && VecOp.getOpcode() == ISD::BUILD_VECTOR) ||
VecOp.getOpcode() == ISD::SPLAT_VECTOR) &&
TLI.isTypeLegal(VecVT) &&
(VecOp.hasOneUse() || TLI.aggressivelyPreferBuildVectorSources(VecVT))) {
assert((VecOp.getOpcode() != ISD::BUILD_VECTOR ||
VecVT.isFixedLengthVector()) &&
"BUILD_VECTOR used for scalable vectors");
unsigned IndexVal =
VecOp.getOpcode() == ISD::BUILD_VECTOR ? IndexC->getZExtValue() : 0;
SDValue Elt = VecOp.getOperand(IndexVal);
EVT InEltVT = Elt.getValueType();
// Sometimes build_vector's scalar input types do not match result type.
if (ScalarVT == InEltVT)
return Elt;
// TODO: It may be useful to truncate if free if the build_vector implicitly
// converts.
}
if (VecVT.isScalableVector())
return SDValue();
// All the code from this point onwards assumes fixed width vectors, but it's
// possible that some of the combinations could be made to work for scalable
// vectors too.
unsigned NumElts = VecVT.getVectorNumElements();
unsigned VecEltBitWidth = VecVT.getScalarSizeInBits();
// TODO: These transforms should not require the 'hasOneUse' restriction, but
// there are regressions on multiple targets without it. We can end up with a
// mess of scalar and vector code if we reduce only part of the DAG to scalar.
if (IndexC && VecOp.getOpcode() == ISD::BITCAST && VecVT.isInteger() &&
VecOp.hasOneUse()) {
// The vector index of the LSBs of the source depend on the endian-ness.
bool IsLE = DAG.getDataLayout().isLittleEndian();
unsigned ExtractIndex = IndexC->getZExtValue();
// extract_elt (v2i32 (bitcast i64:x)), BCTruncElt -> i32 (trunc i64:x)
unsigned BCTruncElt = IsLE ? 0 : NumElts - 1;
SDValue BCSrc = VecOp.getOperand(0);
if (ExtractIndex == BCTruncElt && BCSrc.getValueType().isScalarInteger())
return DAG.getNode(ISD::TRUNCATE, DL, ScalarVT, BCSrc);
if (LegalTypes && BCSrc.getValueType().isInteger() &&
BCSrc.getOpcode() == ISD::SCALAR_TO_VECTOR) {
// ext_elt (bitcast (scalar_to_vec i64 X to v2i64) to v4i32), TruncElt -->
// trunc i64 X to i32
SDValue X = BCSrc.getOperand(0);
assert(X.getValueType().isScalarInteger() && ScalarVT.isScalarInteger() &&
"Extract element and scalar to vector can't change element type "
"from FP to integer.");
unsigned XBitWidth = X.getValueSizeInBits();
BCTruncElt = IsLE ? 0 : XBitWidth / VecEltBitWidth - 1;
// An extract element return value type can be wider than its vector
// operand element type. In that case, the high bits are undefined, so
// it's possible that we may need to extend rather than truncate.
if (ExtractIndex == BCTruncElt && XBitWidth > VecEltBitWidth) {
assert(XBitWidth % VecEltBitWidth == 0 &&
"Scalar bitwidth must be a multiple of vector element bitwidth");
return DAG.getAnyExtOrTrunc(X, DL, ScalarVT);
}
}
}
if (SDValue BO = scalarizeExtractedBinop(N, DAG, LegalOperations))
return BO;
// Transform: (EXTRACT_VECTOR_ELT( VECTOR_SHUFFLE )) -> EXTRACT_VECTOR_ELT.
// We only perform this optimization before the op legalization phase because
// we may introduce new vector instructions which are not backed by TD
// patterns. For example on AVX, extracting elements from a wide vector
// without using extract_subvector. However, if we can find an underlying
// scalar value, then we can always use that.
if (IndexC && VecOp.getOpcode() == ISD::VECTOR_SHUFFLE) {
auto *Shuf = cast<ShuffleVectorSDNode>(VecOp);
// Find the new index to extract from.
int OrigElt = Shuf->getMaskElt(IndexC->getZExtValue());
// Extracting an undef index is undef.
if (OrigElt == -1)
return DAG.getUNDEF(ScalarVT);
// Select the right vector half to extract from.
SDValue SVInVec;
if (OrigElt < (int)NumElts) {
SVInVec = VecOp.getOperand(0);
} else {
SVInVec = VecOp.getOperand(1);
OrigElt -= NumElts;
}
if (SVInVec.getOpcode() == ISD::BUILD_VECTOR) {
SDValue InOp = SVInVec.getOperand(OrigElt);
if (InOp.getValueType() != ScalarVT) {
assert(InOp.getValueType().isInteger() && ScalarVT.isInteger());
InOp = DAG.getSExtOrTrunc(InOp, DL, ScalarVT);
}
return InOp;
}
// FIXME: We should handle recursing on other vector shuffles and
// scalar_to_vector here as well.
if (!LegalOperations ||
// FIXME: Should really be just isOperationLegalOrCustom.
TLI.isOperationLegal(ISD::EXTRACT_VECTOR_ELT, VecVT) ||
TLI.isOperationExpand(ISD::VECTOR_SHUFFLE, VecVT)) {
return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, ScalarVT, SVInVec,
DAG.getVectorIdxConstant(OrigElt, DL));
}
}
// If only EXTRACT_VECTOR_ELT nodes use the source vector we can
// simplify it based on the (valid) extraction indices.
if (llvm::all_of(VecOp->uses(), [&](SDNode *Use) {
return Use->getOpcode() == ISD::EXTRACT_VECTOR_ELT &&
Use->getOperand(0) == VecOp &&
isa<ConstantSDNode>(Use->getOperand(1));
})) {
APInt DemandedElts = APInt::getZero(NumElts);
for (SDNode *Use : VecOp->uses()) {
auto *CstElt = cast<ConstantSDNode>(Use->getOperand(1));
if (CstElt->getAPIntValue().ult(NumElts))
DemandedElts.setBit(CstElt->getZExtValue());
}
if (SimplifyDemandedVectorElts(VecOp, DemandedElts, true)) {
// We simplified the vector operand of this extract element. If this
// extract is not dead, visit it again so it is folded properly.
if (N->getOpcode() != ISD::DELETED_NODE)
AddToWorklist(N);
return SDValue(N, 0);
}
APInt DemandedBits = APInt::getAllOnes(VecEltBitWidth);
if (SimplifyDemandedBits(VecOp, DemandedBits, DemandedElts, true)) {
// We simplified the vector operand of this extract element. If this
// extract is not dead, visit it again so it is folded properly.
if (N->getOpcode() != ISD::DELETED_NODE)
AddToWorklist(N);
return SDValue(N, 0);
}
}
// Everything under here is trying to match an extract of a loaded value.
// If the result of load has to be truncated, then it's not necessarily
// profitable.
bool BCNumEltsChanged = false;
EVT ExtVT = VecVT.getVectorElementType();
EVT LVT = ExtVT;
if (ScalarVT.bitsLT(LVT) && !TLI.isTruncateFree(LVT, ScalarVT))
return SDValue();
if (VecOp.getOpcode() == ISD::BITCAST) {
// Don't duplicate a load with other uses.
if (!VecOp.hasOneUse())
return SDValue();
EVT BCVT = VecOp.getOperand(0).getValueType();
if (!BCVT.isVector() || ExtVT.bitsGT(BCVT.getVectorElementType()))
return SDValue();
if (NumElts != BCVT.getVectorNumElements())
BCNumEltsChanged = true;
VecOp = VecOp.getOperand(0);
ExtVT = BCVT.getVectorElementType();
}
// extract (vector load $addr), i --> load $addr + i * size
if (!LegalOperations && !IndexC && VecOp.hasOneUse() &&
ISD::isNormalLoad(VecOp.getNode()) &&
!Index->hasPredecessor(VecOp.getNode())) {
auto *VecLoad = dyn_cast<LoadSDNode>(VecOp);
if (VecLoad && VecLoad->isSimple())
return scalarizeExtractedVectorLoad(N, VecVT, Index, VecLoad);
}
// Perform only after legalization to ensure build_vector / vector_shuffle
// optimizations have already been done.
if (!LegalOperations || !IndexC)
return SDValue();
// (vextract (v4f32 load $addr), c) -> (f32 load $addr+c*size)
// (vextract (v4f32 s2v (f32 load $addr)), c) -> (f32 load $addr+c*size)
// (vextract (v4f32 shuffle (load $addr), <1,u,u,u>), 0) -> (f32 load $addr)
int Elt = IndexC->getZExtValue();
LoadSDNode *LN0 = nullptr;
if (ISD::isNormalLoad(VecOp.getNode())) {
LN0 = cast<LoadSDNode>(VecOp);
} else if (VecOp.getOpcode() == ISD::SCALAR_TO_VECTOR &&
VecOp.getOperand(0).getValueType() == ExtVT &&
ISD::isNormalLoad(VecOp.getOperand(0).getNode())) {
// Don't duplicate a load with other uses.
if (!VecOp.hasOneUse())
return SDValue();
LN0 = cast<LoadSDNode>(VecOp.getOperand(0));
}
if (auto *Shuf = dyn_cast<ShuffleVectorSDNode>(VecOp)) {
// (vextract (vector_shuffle (load $addr), v2, <1, u, u, u>), 1)
// =>
// (load $addr+1*size)
// Don't duplicate a load with other uses.
if (!VecOp.hasOneUse())
return SDValue();
// If the bit convert changed the number of elements, it is unsafe
// to examine the mask.
if (BCNumEltsChanged)
return SDValue();
// Select the input vector, guarding against out of range extract vector.
int Idx = (Elt > (int)NumElts) ? -1 : Shuf->getMaskElt(Elt);
VecOp = (Idx < (int)NumElts) ? VecOp.getOperand(0) : VecOp.getOperand(1);
if (VecOp.getOpcode() == ISD::BITCAST) {
// Don't duplicate a load with other uses.
if (!VecOp.hasOneUse())
return SDValue();
VecOp = VecOp.getOperand(0);
}
if (ISD::isNormalLoad(VecOp.getNode())) {
LN0 = cast<LoadSDNode>(VecOp);
Elt = (Idx < (int)NumElts) ? Idx : Idx - (int)NumElts;
Index = DAG.getConstant(Elt, DL, Index.getValueType());
}
} else if (VecOp.getOpcode() == ISD::CONCAT_VECTORS && !BCNumEltsChanged &&
VecVT.getVectorElementType() == ScalarVT &&
(!LegalTypes ||
TLI.isTypeLegal(
VecOp.getOperand(0).getValueType().getVectorElementType()))) {
// extract_vector_elt (concat_vectors v2i16:a, v2i16:b), 0
// -> extract_vector_elt a, 0
// extract_vector_elt (concat_vectors v2i16:a, v2i16:b), 1
// -> extract_vector_elt a, 1
// extract_vector_elt (concat_vectors v2i16:a, v2i16:b), 2
// -> extract_vector_elt b, 0
// extract_vector_elt (concat_vectors v2i16:a, v2i16:b), 3
// -> extract_vector_elt b, 1
SDLoc SL(N);
EVT ConcatVT = VecOp.getOperand(0).getValueType();
unsigned ConcatNumElts = ConcatVT.getVectorNumElements();
SDValue NewIdx = DAG.getConstant(Elt % ConcatNumElts, SL,
Index.getValueType());
SDValue ConcatOp = VecOp.getOperand(Elt / ConcatNumElts);
SDValue Elt = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, SL,
ConcatVT.getVectorElementType(),
ConcatOp, NewIdx);
return DAG.getNode(ISD::BITCAST, SL, ScalarVT, Elt);
}
// Make sure we found a non-volatile load and the extractelement is
// the only use.
if (!LN0 || !LN0->hasNUsesOfValue(1,0) || !LN0->isSimple())
return SDValue();
// If Idx was -1 above, Elt is going to be -1, so just return undef.
if (Elt == -1)
return DAG.getUNDEF(LVT);
return scalarizeExtractedVectorLoad(N, VecVT, Index, LN0);
}
// Simplify (build_vec (ext )) to (bitcast (build_vec ))
SDValue DAGCombiner::reduceBuildVecExtToExtBuildVec(SDNode *N) {
// We perform this optimization post type-legalization because
// the type-legalizer often scalarizes integer-promoted vectors.
// Performing this optimization before may create bit-casts which
// will be type-legalized to complex code sequences.
// We perform this optimization only before the operation legalizer because we
// may introduce illegal operations.
if (Level != AfterLegalizeVectorOps && Level != AfterLegalizeTypes)
return SDValue();
unsigned NumInScalars = N->getNumOperands();
SDLoc DL(N);
EVT VT = N->getValueType(0);
// Check to see if this is a BUILD_VECTOR of a bunch of values
// which come from any_extend or zero_extend nodes. If so, we can create
// a new BUILD_VECTOR using bit-casts which may enable other BUILD_VECTOR
// optimizations. We do not handle sign-extend because we can't fill the sign
// using shuffles.
EVT SourceType = MVT::Other;
bool AllAnyExt = true;
for (unsigned i = 0; i != NumInScalars; ++i) {
SDValue In = N->getOperand(i);
// Ignore undef inputs.
if (In.isUndef()) continue;
bool AnyExt = In.getOpcode() == ISD::ANY_EXTEND;
bool ZeroExt = In.getOpcode() == ISD::ZERO_EXTEND;
// Abort if the element is not an extension.
if (!ZeroExt && !AnyExt) {
SourceType = MVT::Other;
break;
}
// The input is a ZeroExt or AnyExt. Check the original type.
EVT InTy = In.getOperand(0).getValueType();
// Check that all of the widened source types are the same.
if (SourceType == MVT::Other)
// First time.
SourceType = InTy;
else if (InTy != SourceType) {
// Multiple income types. Abort.
SourceType = MVT::Other;
break;
}
// Check if all of the extends are ANY_EXTENDs.
AllAnyExt &= AnyExt;
}
// In order to have valid types, all of the inputs must be extended from the
// same source type and all of the inputs must be any or zero extend.
// Scalar sizes must be a power of two.
EVT OutScalarTy = VT.getScalarType();
bool ValidTypes = SourceType != MVT::Other &&
isPowerOf2_32(OutScalarTy.getSizeInBits()) &&
isPowerOf2_32(SourceType.getSizeInBits());
// Create a new simpler BUILD_VECTOR sequence which other optimizations can
// turn into a single shuffle instruction.
if (!ValidTypes)
return SDValue();
// If we already have a splat buildvector, then don't fold it if it means
// introducing zeros.
if (!AllAnyExt && DAG.isSplatValue(SDValue(N, 0), /*AllowUndefs*/ true))
return SDValue();
bool isLE = DAG.getDataLayout().isLittleEndian();
unsigned ElemRatio = OutScalarTy.getSizeInBits()/SourceType.getSizeInBits();
assert(ElemRatio > 1 && "Invalid element size ratio");
SDValue Filler = AllAnyExt ? DAG.getUNDEF(SourceType):
DAG.getConstant(0, DL, SourceType);
unsigned NewBVElems = ElemRatio * VT.getVectorNumElements();
SmallVector<SDValue, 8> Ops(NewBVElems, Filler);
// Populate the new build_vector
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
SDValue Cast = N->getOperand(i);
assert((Cast.getOpcode() == ISD::ANY_EXTEND ||
Cast.getOpcode() == ISD::ZERO_EXTEND ||
Cast.isUndef()) && "Invalid cast opcode");
SDValue In;
if (Cast.isUndef())
In = DAG.getUNDEF(SourceType);
else
In = Cast->getOperand(0);
unsigned Index = isLE ? (i * ElemRatio) :
(i * ElemRatio + (ElemRatio - 1));
assert(Index < Ops.size() && "Invalid index");
Ops[Index] = In;
}
// The type of the new BUILD_VECTOR node.
EVT VecVT = EVT::getVectorVT(*DAG.getContext(), SourceType, NewBVElems);
assert(VecVT.getSizeInBits() == VT.getSizeInBits() &&
"Invalid vector size");
// Check if the new vector type is legal.
if (!isTypeLegal(VecVT) ||
(!TLI.isOperationLegal(ISD::BUILD_VECTOR, VecVT) &&
TLI.isOperationLegal(ISD::BUILD_VECTOR, VT)))
return SDValue();
// Make the new BUILD_VECTOR.
SDValue BV = DAG.getBuildVector(VecVT, DL, Ops);
// The new BUILD_VECTOR node has the potential to be further optimized.
AddToWorklist(BV.getNode());
// Bitcast to the desired type.
return DAG.getBitcast(VT, BV);
}
// Simplify (build_vec (trunc $1)
// (trunc (srl $1 half-width))
// (trunc (srl $1 (2 * half-width))) …)
// to (bitcast $1)
SDValue DAGCombiner::reduceBuildVecTruncToBitCast(SDNode *N) {
assert(N->getOpcode() == ISD::BUILD_VECTOR && "Expected build vector");
// Only for little endian
if (!DAG.getDataLayout().isLittleEndian())
return SDValue();
SDLoc DL(N);
EVT VT = N->getValueType(0);
EVT OutScalarTy = VT.getScalarType();
uint64_t ScalarTypeBitsize = OutScalarTy.getSizeInBits();
// Only for power of two types to be sure that bitcast works well
if (!isPowerOf2_64(ScalarTypeBitsize))
return SDValue();
unsigned NumInScalars = N->getNumOperands();
// Look through bitcasts
auto PeekThroughBitcast = [](SDValue Op) {
if (Op.getOpcode() == ISD::BITCAST)
return Op.getOperand(0);
return Op;
};
// The source value where all the parts are extracted.
SDValue Src;
for (unsigned i = 0; i != NumInScalars; ++i) {
SDValue In = PeekThroughBitcast(N->getOperand(i));
// Ignore undef inputs.
if (In.isUndef()) continue;
if (In.getOpcode() != ISD::TRUNCATE)
return SDValue();
In = PeekThroughBitcast(In.getOperand(0));
if (In.getOpcode() != ISD::SRL) {
// For now only build_vec without shuffling, handle shifts here in the
// future.
if (i != 0)
return SDValue();
Src = In;
} else {
// In is SRL
SDValue part = PeekThroughBitcast(In.getOperand(0));
if (!Src) {
Src = part;
} else if (Src != part) {
// Vector parts do not stem from the same variable
return SDValue();
}
SDValue ShiftAmtVal = In.getOperand(1);
if (!isa<ConstantSDNode>(ShiftAmtVal))
return SDValue();
uint64_t ShiftAmt = In.getConstantOperandVal(1);
// The extracted value is not extracted at the right position
if (ShiftAmt != i * ScalarTypeBitsize)
return SDValue();
}
}
// Only cast if the size is the same
if (Src.getValueType().getSizeInBits() != VT.getSizeInBits())
return SDValue();
return DAG.getBitcast(VT, Src);
}
SDValue DAGCombiner::createBuildVecShuffle(const SDLoc &DL, SDNode *N,
ArrayRef<int> VectorMask,
SDValue VecIn1, SDValue VecIn2,
unsigned LeftIdx, bool DidSplitVec) {
SDValue ZeroIdx = DAG.getVectorIdxConstant(0, DL);
EVT VT = N->getValueType(0);
EVT InVT1 = VecIn1.getValueType();
EVT InVT2 = VecIn2.getNode() ? VecIn2.getValueType() : InVT1;
unsigned NumElems = VT.getVectorNumElements();
unsigned ShuffleNumElems = NumElems;
// If we artificially split a vector in two already, then the offsets in the
// operands will all be based off of VecIn1, even those in VecIn2.
unsigned Vec2Offset = DidSplitVec ? 0 : InVT1.getVectorNumElements();
uint64_t VTSize = VT.getFixedSizeInBits();
uint64_t InVT1Size = InVT1.getFixedSizeInBits();
uint64_t InVT2Size = InVT2.getFixedSizeInBits();
assert(InVT2Size <= InVT1Size &&
"Inputs must be sorted to be in non-increasing vector size order.");
// We can't generate a shuffle node with mismatched input and output types.
// Try to make the types match the type of the output.
if (InVT1 != VT || InVT2 != VT) {
if ((VTSize % InVT1Size == 0) && InVT1 == InVT2) {
// If the output vector length is a multiple of both input lengths,
// we can concatenate them and pad the rest with undefs.
unsigned NumConcats = VTSize / InVT1Size;
assert(NumConcats >= 2 && "Concat needs at least two inputs!");
SmallVector<SDValue, 2> ConcatOps(NumConcats, DAG.getUNDEF(InVT1));
ConcatOps[0] = VecIn1;
ConcatOps[1] = VecIn2 ? VecIn2 : DAG.getUNDEF(InVT1);
VecIn1 = DAG.getNode(ISD::CONCAT_VECTORS, DL, VT, ConcatOps);
VecIn2 = SDValue();
} else if (InVT1Size == VTSize * 2) {
if (!TLI.isExtractSubvectorCheap(VT, InVT1, NumElems))
return SDValue();
if (!VecIn2.getNode()) {
// If we only have one input vector, and it's twice the size of the
// output, split it in two.
VecIn2 = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, VT, VecIn1,
DAG.getVectorIdxConstant(NumElems, DL));
VecIn1 = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, VT, VecIn1, ZeroIdx);
// Since we now have shorter input vectors, adjust the offset of the
// second vector's start.
Vec2Offset = NumElems;
} else {
assert(InVT2Size <= InVT1Size &&
"Second input is not going to be larger than the first one.");
// VecIn1 is wider than the output, and we have another, possibly
// smaller input. Pad the smaller input with undefs, shuffle at the
// input vector width, and extract the output.
// The shuffle type is different than VT, so check legality again.
if (LegalOperations &&
!TLI.isOperationLegal(ISD::VECTOR_SHUFFLE, InVT1))
return SDValue();
// Legalizing INSERT_SUBVECTOR is tricky - you basically have to
// lower it back into a BUILD_VECTOR. So if the inserted type is
// illegal, don't even try.
if (InVT1 != InVT2) {
if (!TLI.isTypeLegal(InVT2))
return SDValue();
VecIn2 = DAG.getNode(ISD::INSERT_SUBVECTOR, DL, InVT1,
DAG.getUNDEF(InVT1), VecIn2, ZeroIdx);
}
ShuffleNumElems = NumElems * 2;
}
} else if (InVT2Size * 2 == VTSize && InVT1Size == VTSize) {
SmallVector<SDValue, 2> ConcatOps(2, DAG.getUNDEF(InVT2));
ConcatOps[0] = VecIn2;
VecIn2 = DAG.getNode(ISD::CONCAT_VECTORS, DL, VT, ConcatOps);
} else {
// TODO: Support cases where the length mismatch isn't exactly by a
// factor of 2.
// TODO: Move this check upwards, so that if we have bad type
// mismatches, we don't create any DAG nodes.
return SDValue();
}
}
// Initialize mask to undef.
SmallVector<int, 8> Mask(ShuffleNumElems, -1);
// Only need to run up to the number of elements actually used, not the
// total number of elements in the shuffle - if we are shuffling a wider
// vector, the high lanes should be set to undef.
for (unsigned i = 0; i != NumElems; ++i) {
if (VectorMask[i] <= 0)
continue;
unsigned ExtIndex = N->getOperand(i).getConstantOperandVal(1);
if (VectorMask[i] == (int)LeftIdx) {
Mask[i] = ExtIndex;
} else if (VectorMask[i] == (int)LeftIdx + 1) {
Mask[i] = Vec2Offset + ExtIndex;
}
}
// The type the input vectors may have changed above.
InVT1 = VecIn1.getValueType();
// If we already have a VecIn2, it should have the same type as VecIn1.
// If we don't, get an undef/zero vector of the appropriate type.
VecIn2 = VecIn2.getNode() ? VecIn2 : DAG.getUNDEF(InVT1);
assert(InVT1 == VecIn2.getValueType() && "Unexpected second input type.");
SDValue Shuffle = DAG.getVectorShuffle(InVT1, DL, VecIn1, VecIn2, Mask);
if (ShuffleNumElems > NumElems)
Shuffle = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, VT, Shuffle, ZeroIdx);
return Shuffle;
}
static SDValue reduceBuildVecToShuffleWithZero(SDNode *BV, SelectionDAG &DAG) {
assert(BV->getOpcode() == ISD::BUILD_VECTOR && "Expected build vector");
// First, determine where the build vector is not undef.
// TODO: We could extend this to handle zero elements as well as undefs.
int NumBVOps = BV->getNumOperands();
int ZextElt = -1;
for (int i = 0; i != NumBVOps; ++i) {
SDValue Op = BV->getOperand(i);
if (Op.isUndef())
continue;
if (ZextElt == -1)
ZextElt = i;
else
return SDValue();
}
// Bail out if there's no non-undef element.
if (ZextElt == -1)
return SDValue();
// The build vector contains some number of undef elements and exactly
// one other element. That other element must be a zero-extended scalar
// extracted from a vector at a constant index to turn this into a shuffle.
// Also, require that the build vector does not implicitly truncate/extend
// its elements.
// TODO: This could be enhanced to allow ANY_EXTEND as well as ZERO_EXTEND.
EVT VT = BV->getValueType(0);
SDValue Zext = BV->getOperand(ZextElt);
if (Zext.getOpcode() != ISD::ZERO_EXTEND || !Zext.hasOneUse() ||
Zext.getOperand(0).getOpcode() != ISD::EXTRACT_VECTOR_ELT ||
!isa<ConstantSDNode>(Zext.getOperand(0).getOperand(1)) ||
Zext.getValueSizeInBits() != VT.getScalarSizeInBits())
return SDValue();
// The zero-extend must be a multiple of the source size, and we must be
// building a vector of the same size as the source of the extract element.
SDValue Extract = Zext.getOperand(0);
unsigned DestSize = Zext.getValueSizeInBits();
unsigned SrcSize = Extract.getValueSizeInBits();
if (DestSize % SrcSize != 0 ||
Extract.getOperand(0).getValueSizeInBits() != VT.getSizeInBits())
return SDValue();
// Create a shuffle mask that will combine the extracted element with zeros
// and undefs.
int ZextRatio = DestSize / SrcSize;
int NumMaskElts = NumBVOps * ZextRatio;
SmallVector<int, 32> ShufMask(NumMaskElts, -1);
for (int i = 0; i != NumMaskElts; ++i) {
if (i / ZextRatio == ZextElt) {
// The low bits of the (potentially translated) extracted element map to
// the source vector. The high bits map to zero. We will use a zero vector
// as the 2nd source operand of the shuffle, so use the 1st element of
// that vector (mask value is number-of-elements) for the high bits.
if (i % ZextRatio == 0)
ShufMask[i] = Extract.getConstantOperandVal(1);
else
ShufMask[i] = NumMaskElts;
}
// Undef elements of the build vector remain undef because we initialize
// the shuffle mask with -1.
}
// buildvec undef, ..., (zext (extractelt V, IndexC)), undef... -->
// bitcast (shuffle V, ZeroVec, VectorMask)
SDLoc DL(BV);
EVT VecVT = Extract.getOperand(0).getValueType();
SDValue ZeroVec = DAG.getConstant(0, DL, VecVT);
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
SDValue Shuf = TLI.buildLegalVectorShuffle(VecVT, DL, Extract.getOperand(0),
ZeroVec, ShufMask, DAG);
if (!Shuf)
return SDValue();
return DAG.getBitcast(VT, Shuf);
}
// FIXME: promote to STLExtras.
template <typename R, typename T>
static auto getFirstIndexOf(R &&Range, const T &Val) {
auto I = find(Range, Val);
if (I == Range.end())
return static_cast<decltype(std::distance(Range.begin(), I))>(-1);
return std::distance(Range.begin(), I);
}
// Check to see if this is a BUILD_VECTOR of a bunch of EXTRACT_VECTOR_ELT
// operations. If the types of the vectors we're extracting from allow it,
// turn this into a vector_shuffle node.
SDValue DAGCombiner::reduceBuildVecToShuffle(SDNode *N) {
SDLoc DL(N);
EVT VT = N->getValueType(0);
// Only type-legal BUILD_VECTOR nodes are converted to shuffle nodes.
if (!isTypeLegal(VT))
return SDValue();
if (SDValue V = reduceBuildVecToShuffleWithZero(N, DAG))
return V;
// May only combine to shuffle after legalize if shuffle is legal.
if (LegalOperations && !TLI.isOperationLegal(ISD::VECTOR_SHUFFLE, VT))
return SDValue();
bool UsesZeroVector = false;
unsigned NumElems = N->getNumOperands();
// Record, for each element of the newly built vector, which input vector
// that element comes from. -1 stands for undef, 0 for the zero vector,
// and positive values for the input vectors.
// VectorMask maps each element to its vector number, and VecIn maps vector
// numbers to their initial SDValues.
SmallVector<int, 8> VectorMask(NumElems, -1);
SmallVector<SDValue, 8> VecIn;
VecIn.push_back(SDValue());
for (unsigned i = 0; i != NumElems; ++i) {
SDValue Op = N->getOperand(i);
if (Op.isUndef())
continue;
// See if we can use a blend with a zero vector.
// TODO: Should we generalize this to a blend with an arbitrary constant
// vector?
if (isNullConstant(Op) || isNullFPConstant(Op)) {
UsesZeroVector = true;
VectorMask[i] = 0;
continue;
}
// Not an undef or zero. If the input is something other than an
// EXTRACT_VECTOR_ELT with an in-range constant index, bail out.
if (Op.getOpcode() != ISD::EXTRACT_VECTOR_ELT ||
!isa<ConstantSDNode>(Op.getOperand(1)))
return SDValue();
SDValue ExtractedFromVec = Op.getOperand(0);
if (ExtractedFromVec.getValueType().isScalableVector())
return SDValue();
const APInt &ExtractIdx = Op.getConstantOperandAPInt(1);
if (ExtractIdx.uge(ExtractedFromVec.getValueType().getVectorNumElements()))
return SDValue();
// All inputs must have the same element type as the output.
if (VT.getVectorElementType() !=
ExtractedFromVec.getValueType().getVectorElementType())
return SDValue();
// Have we seen this input vector before?
// The vectors are expected to be tiny (usually 1 or 2 elements), so using
// a map back from SDValues to numbers isn't worth it.
int Idx = getFirstIndexOf(VecIn, ExtractedFromVec);
if (Idx == -1) { // A new source vector?
Idx = VecIn.size();
VecIn.push_back(ExtractedFromVec);
}
VectorMask[i] = Idx;
}
// If we didn't find at least one input vector, bail out.
if (VecIn.size() < 2)
return SDValue();
// If all the Operands of BUILD_VECTOR extract from same
// vector, then split the vector efficiently based on the maximum
// vector access index and adjust the VectorMask and
// VecIn accordingly.
bool DidSplitVec = false;
if (VecIn.size() == 2) {
unsigned MaxIndex = 0;
unsigned NearestPow2 = 0;
SDValue Vec = VecIn.back();
EVT InVT = Vec.getValueType();
SmallVector<unsigned, 8> IndexVec(NumElems, 0);
for (unsigned i = 0; i < NumElems; i++) {
if (VectorMask[i] <= 0)
continue;
unsigned Index = N->getOperand(i).getConstantOperandVal(1);
IndexVec[i] = Index;
MaxIndex = std::max(MaxIndex, Index);
}
NearestPow2 = PowerOf2Ceil(MaxIndex);
if (InVT.isSimple() && NearestPow2 > 2 && MaxIndex < NearestPow2 &&
NumElems * 2 < NearestPow2) {
unsigned SplitSize = NearestPow2 / 2;
EVT SplitVT = EVT::getVectorVT(*DAG.getContext(),
InVT.getVectorElementType(), SplitSize);
if (TLI.isTypeLegal(SplitVT) &&
SplitSize + SplitVT.getVectorNumElements() <=
InVT.getVectorNumElements()) {
SDValue VecIn2 = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, SplitVT, Vec,
DAG.getVectorIdxConstant(SplitSize, DL));
SDValue VecIn1 = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, SplitVT, Vec,
DAG.getVectorIdxConstant(0, DL));
VecIn.pop_back();
VecIn.push_back(VecIn1);
VecIn.push_back(VecIn2);
DidSplitVec = true;
for (unsigned i = 0; i < NumElems; i++) {
if (VectorMask[i] <= 0)
continue;
VectorMask[i] = (IndexVec[i] < SplitSize) ? 1 : 2;
}
}
}
}
// Sort input vectors by decreasing vector element count,
// while preserving the relative order of equally-sized vectors.
// Note that we keep the first "implicit zero vector as-is.
SmallVector<SDValue, 8> SortedVecIn(VecIn);
llvm::stable_sort(MutableArrayRef<SDValue>(SortedVecIn).drop_front(),
[](const SDValue &a, const SDValue &b) {
return a.getValueType().getVectorNumElements() >
b.getValueType().getVectorNumElements();
});
// We now also need to rebuild the VectorMask, because it referenced element
// order in VecIn, and we just sorted them.
for (int &SourceVectorIndex : VectorMask) {
if (SourceVectorIndex <= 0)
continue;
unsigned Idx = getFirstIndexOf(SortedVecIn, VecIn[SourceVectorIndex]);
assert(Idx > 0 && Idx < SortedVecIn.size() &&
VecIn[SourceVectorIndex] == SortedVecIn[Idx] && "Remapping failure");
SourceVectorIndex = Idx;
}
VecIn = std::move(SortedVecIn);
// TODO: Should this fire if some of the input vectors has illegal type (like
// it does now), or should we let legalization run its course first?
// Shuffle phase:
// Take pairs of vectors, and shuffle them so that the result has elements
// from these vectors in the correct places.
// For example, given:
// t10: i32 = extract_vector_elt t1, Constant:i64<0>
// t11: i32 = extract_vector_elt t2, Constant:i64<0>
// t12: i32 = extract_vector_elt t3, Constant:i64<0>
// t13: i32 = extract_vector_elt t1, Constant:i64<1>
// t14: v4i32 = BUILD_VECTOR t10, t11, t12, t13
// We will generate:
// t20: v4i32 = vector_shuffle<0,4,u,1> t1, t2
// t21: v4i32 = vector_shuffle<u,u,0,u> t3, undef
SmallVector<SDValue, 4> Shuffles;
for (unsigned In = 0, Len = (VecIn.size() / 2); In < Len; ++In) {
unsigned LeftIdx = 2 * In + 1;
SDValue VecLeft = VecIn[LeftIdx];
SDValue VecRight =
(LeftIdx + 1) < VecIn.size() ? VecIn[LeftIdx + 1] : SDValue();
if (SDValue Shuffle = createBuildVecShuffle(DL, N, VectorMask, VecLeft,
VecRight, LeftIdx, DidSplitVec))
Shuffles.push_back(Shuffle);
else
return SDValue();
}
// If we need the zero vector as an "ingredient" in the blend tree, add it
// to the list of shuffles.
if (UsesZeroVector)
Shuffles.push_back(VT.isInteger() ? DAG.getConstant(0, DL, VT)
: DAG.getConstantFP(0.0, DL, VT));
// If we only have one shuffle, we're done.
if (Shuffles.size() == 1)
return Shuffles[0];
// Update the vector mask to point to the post-shuffle vectors.
for (int &Vec : VectorMask)
if (Vec == 0)
Vec = Shuffles.size() - 1;
else
Vec = (Vec - 1) / 2;
// More than one shuffle. Generate a binary tree of blends, e.g. if from
// the previous step we got the set of shuffles t10, t11, t12, t13, we will
// generate:
// t10: v8i32 = vector_shuffle<0,8,u,u,u,u,u,u> t1, t2
// t11: v8i32 = vector_shuffle<u,u,0,8,u,u,u,u> t3, t4
// t12: v8i32 = vector_shuffle<u,u,u,u,0,8,u,u> t5, t6
// t13: v8i32 = vector_shuffle<u,u,u,u,u,u,0,8> t7, t8
// t20: v8i32 = vector_shuffle<0,1,10,11,u,u,u,u> t10, t11
// t21: v8i32 = vector_shuffle<u,u,u,u,4,5,14,15> t12, t13
// t30: v8i32 = vector_shuffle<0,1,2,3,12,13,14,15> t20, t21
// Make sure the initial size of the shuffle list is even.
if (Shuffles.size() % 2)
Shuffles.push_back(DAG.getUNDEF(VT));
for (unsigned CurSize = Shuffles.size(); CurSize > 1; CurSize /= 2) {
if (CurSize % 2) {
Shuffles[CurSize] = DAG.getUNDEF(VT);
CurSize++;
}
for (unsigned In = 0, Len = CurSize / 2; In < Len; ++In) {
int Left = 2 * In;
int Right = 2 * In + 1;
SmallVector<int, 8> Mask(NumElems, -1);
SDValue L = Shuffles[Left];
ArrayRef<int> LMask;
bool IsLeftShuffle = L.getOpcode() == ISD::VECTOR_SHUFFLE &&
L.use_empty() && L.getOperand(1).isUndef() &&
L.getOperand(0).getValueType() == L.getValueType();
if (IsLeftShuffle) {
LMask = cast<ShuffleVectorSDNode>(L.getNode())->getMask();
L = L.getOperand(0);
}
SDValue R = Shuffles[Right];
ArrayRef<int> RMask;
bool IsRightShuffle = R.getOpcode() == ISD::VECTOR_SHUFFLE &&
R.use_empty() && R.getOperand(1).isUndef() &&
R.getOperand(0).getValueType() == R.getValueType();
if (IsRightShuffle) {
RMask = cast<ShuffleVectorSDNode>(R.getNode())->getMask();
R = R.getOperand(0);
}
for (unsigned I = 0; I != NumElems; ++I) {
if (VectorMask[I] == Left) {
Mask[I] = I;
if (IsLeftShuffle)
Mask[I] = LMask[I];
VectorMask[I] = In;
} else if (VectorMask[I] == Right) {
Mask[I] = I + NumElems;
if (IsRightShuffle)
Mask[I] = RMask[I] + NumElems;
VectorMask[I] = In;
}
}
Shuffles[In] = DAG.getVectorShuffle(VT, DL, L, R, Mask);
}
}
return Shuffles[0];
}
// Try to turn a build vector of zero extends of extract vector elts into a
// a vector zero extend and possibly an extract subvector.
// TODO: Support sign extend?
// TODO: Allow undef elements?
SDValue DAGCombiner::convertBuildVecZextToZext(SDNode *N) {
if (LegalOperations)
return SDValue();
EVT VT = N->getValueType(0);
bool FoundZeroExtend = false;
SDValue Op0 = N->getOperand(0);
auto checkElem = [&](SDValue Op) -> int64_t {
unsigned Opc = Op.getOpcode();
FoundZeroExtend |= (Opc == ISD::ZERO_EXTEND);
if ((Opc == ISD::ZERO_EXTEND || Opc == ISD::ANY_EXTEND) &&
Op.getOperand(0).getOpcode() == ISD::EXTRACT_VECTOR_ELT &&
Op0.getOperand(0).getOperand(0) == Op.getOperand(0).getOperand(0))
if (auto *C = dyn_cast<ConstantSDNode>(Op.getOperand(0).getOperand(1)))
return C->getZExtValue();
return -1;
};
// Make sure the first element matches
// (zext (extract_vector_elt X, C))
// Offset must be a constant multiple of the
// known-minimum vector length of the result type.
int64_t Offset = checkElem(Op0);
if (Offset < 0 || (Offset % VT.getVectorNumElements()) != 0)
return SDValue();
unsigned NumElems = N->getNumOperands();
SDValue In = Op0.getOperand(0).getOperand(0);
EVT InSVT = In.getValueType().getScalarType();
EVT InVT = EVT::getVectorVT(*DAG.getContext(), InSVT, NumElems);
// Don't create an illegal input type after type legalization.
if (LegalTypes && !TLI.isTypeLegal(InVT))
return SDValue();
// Ensure all the elements come from the same vector and are adjacent.
for (unsigned i = 1; i != NumElems; ++i) {
if ((Offset + i) != checkElem(N->getOperand(i)))
return SDValue();
}
SDLoc DL(N);
In = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, InVT, In,
Op0.getOperand(0).getOperand(1));
return DAG.getNode(FoundZeroExtend ? ISD::ZERO_EXTEND : ISD::ANY_EXTEND, DL,
VT, In);
}
SDValue DAGCombiner::visitBUILD_VECTOR(SDNode *N) {
EVT VT = N->getValueType(0);
// A vector built entirely of undefs is undef.
if (ISD::allOperandsUndef(N))
return DAG.getUNDEF(VT);
// If this is a splat of a bitcast from another vector, change to a
// concat_vector.
// For example:
// (build_vector (i64 (bitcast (v2i32 X))), (i64 (bitcast (v2i32 X)))) ->
// (v2i64 (bitcast (concat_vectors (v2i32 X), (v2i32 X))))
//
// If X is a build_vector itself, the concat can become a larger build_vector.
// TODO: Maybe this is useful for non-splat too?
if (!LegalOperations) {
if (SDValue Splat = cast<BuildVectorSDNode>(N)->getSplatValue()) {
Splat = peekThroughBitcasts(Splat);
EVT SrcVT = Splat.getValueType();
if (SrcVT.isVector()) {
unsigned NumElts = N->getNumOperands() * SrcVT.getVectorNumElements();
EVT NewVT = EVT::getVectorVT(*DAG.getContext(),
SrcVT.getVectorElementType(), NumElts);
if (!LegalTypes || TLI.isTypeLegal(NewVT)) {
SmallVector<SDValue, 8> Ops(N->getNumOperands(), Splat);
SDValue Concat = DAG.getNode(ISD::CONCAT_VECTORS, SDLoc(N),
NewVT, Ops);
return DAG.getBitcast(VT, Concat);
}
}
}
}
// Check if we can express BUILD VECTOR via subvector extract.
if (!LegalTypes && (N->getNumOperands() > 1)) {
SDValue Op0 = N->getOperand(0);
auto checkElem = [&](SDValue Op) -> uint64_t {
if ((Op.getOpcode() == ISD::EXTRACT_VECTOR_ELT) &&
(Op0.getOperand(0) == Op.getOperand(0)))
if (auto CNode = dyn_cast<ConstantSDNode>(Op.getOperand(1)))
return CNode->getZExtValue();
return -1;
};
int Offset = checkElem(Op0);
for (unsigned i = 0; i < N->getNumOperands(); ++i) {
if (Offset + i != checkElem(N->getOperand(i))) {
Offset = -1;
break;
}
}
if ((Offset == 0) &&
(Op0.getOperand(0).getValueType() == N->getValueType(0)))
return Op0.getOperand(0);
if ((Offset != -1) &&
((Offset % N->getValueType(0).getVectorNumElements()) ==
0)) // IDX must be multiple of output size.
return DAG.getNode(ISD::EXTRACT_SUBVECTOR, SDLoc(N), N->getValueType(0),
Op0.getOperand(0), Op0.getOperand(1));
}
if (SDValue V = convertBuildVecZextToZext(N))
return V;
if (SDValue V = reduceBuildVecExtToExtBuildVec(N))
return V;
if (SDValue V = reduceBuildVecTruncToBitCast(N))
return V;
if (SDValue V = reduceBuildVecToShuffle(N))
return V;
// A splat of a single element is a SPLAT_VECTOR if supported on the target.
// Do this late as some of the above may replace the splat.
if (TLI.getOperationAction(ISD::SPLAT_VECTOR, VT) != TargetLowering::Expand)
if (SDValue V = cast<BuildVectorSDNode>(N)->getSplatValue()) {
assert(!V.isUndef() && "Splat of undef should have been handled earlier");
return DAG.getNode(ISD::SPLAT_VECTOR, SDLoc(N), VT, V);
}
return SDValue();
}
static SDValue combineConcatVectorOfScalars(SDNode *N, SelectionDAG &DAG) {
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
EVT OpVT = N->getOperand(0).getValueType();
// If the operands are legal vectors, leave them alone.
if (TLI.isTypeLegal(OpVT))
return SDValue();
SDLoc DL(N);
EVT VT = N->getValueType(0);
SmallVector<SDValue, 8> Ops;
EVT SVT = EVT::getIntegerVT(*DAG.getContext(), OpVT.getSizeInBits());
SDValue ScalarUndef = DAG.getNode(ISD::UNDEF, DL, SVT);
// Keep track of what we encounter.
bool AnyInteger = false;
bool AnyFP = false;
for (const SDValue &Op : N->ops()) {
if (ISD::BITCAST == Op.getOpcode() &&
!Op.getOperand(0).getValueType().isVector())
Ops.push_back(Op.getOperand(0));
else if (ISD::UNDEF == Op.getOpcode())
Ops.push_back(ScalarUndef);
else
return SDValue();
// Note whether we encounter an integer or floating point scalar.
// If it's neither, bail out, it could be something weird like x86mmx.
EVT LastOpVT = Ops.back().getValueType();
if (LastOpVT.isFloatingPoint())
AnyFP = true;
else if (LastOpVT.isInteger())
AnyInteger = true;
else
return SDValue();
}
// If any of the operands is a floating point scalar bitcast to a vector,
// use floating point types throughout, and bitcast everything.
// Replace UNDEFs by another scalar UNDEF node, of the final desired type.
if (AnyFP) {
SVT = EVT::getFloatingPointVT(OpVT.getSizeInBits());
ScalarUndef = DAG.getNode(ISD::UNDEF, DL, SVT);
if (AnyInteger) {
for (SDValue &Op : Ops) {
if (Op.getValueType() == SVT)
continue;
if (Op.isUndef())
Op = ScalarUndef;
else
Op = DAG.getBitcast(SVT, Op);
}
}
}
EVT VecVT = EVT::getVectorVT(*DAG.getContext(), SVT,
VT.getSizeInBits() / SVT.getSizeInBits());
return DAG.getBitcast(VT, DAG.getBuildVector(VecVT, DL, Ops));
}
// Attempt to merge nested concat_vectors/undefs.
// Fold concat_vectors(concat_vectors(x,y,z,w),u,u,concat_vectors(a,b,c,d))
// --> concat_vectors(x,y,z,w,u,u,u,u,u,u,u,u,a,b,c,d)
static SDValue combineConcatVectorOfConcatVectors(SDNode *N,
SelectionDAG &DAG) {
EVT VT = N->getValueType(0);
// Ensure we're concatenating UNDEF and CONCAT_VECTORS nodes of similar types.
EVT SubVT;
SDValue FirstConcat;
for (const SDValue &Op : N->ops()) {
if (Op.isUndef())
continue;
if (Op.getOpcode() != ISD::CONCAT_VECTORS)
return SDValue();
if (!FirstConcat) {
SubVT = Op.getOperand(0).getValueType();
if (!DAG.getTargetLoweringInfo().isTypeLegal(SubVT))
return SDValue();
FirstConcat = Op;
continue;
}
if (SubVT != Op.getOperand(0).getValueType())
return SDValue();
}
assert(FirstConcat && "Concat of all-undefs found");
SmallVector<SDValue> ConcatOps;
for (const SDValue &Op : N->ops()) {
if (Op.isUndef()) {
ConcatOps.append(FirstConcat->getNumOperands(), DAG.getUNDEF(SubVT));
continue;
}
ConcatOps.append(Op->op_begin(), Op->op_end());
}
return DAG.getNode(ISD::CONCAT_VECTORS, SDLoc(N), VT, ConcatOps);
}
// Check to see if this is a CONCAT_VECTORS of a bunch of EXTRACT_SUBVECTOR
// operations. If so, and if the EXTRACT_SUBVECTOR vector inputs come from at
// most two distinct vectors the same size as the result, attempt to turn this
// into a legal shuffle.
static SDValue combineConcatVectorOfExtracts(SDNode *N, SelectionDAG &DAG) {
EVT VT = N->getValueType(0);
EVT OpVT = N->getOperand(0).getValueType();
// We currently can't generate an appropriate shuffle for a scalable vector.
if (VT.isScalableVector())
return SDValue();
int NumElts = VT.getVectorNumElements();
int NumOpElts = OpVT.getVectorNumElements();
SDValue SV0 = DAG.getUNDEF(VT), SV1 = DAG.getUNDEF(VT);
SmallVector<int, 8> Mask;
for (SDValue Op : N->ops()) {
Op = peekThroughBitcasts(Op);
// UNDEF nodes convert to UNDEF shuffle mask values.
if (Op.isUndef()) {
Mask.append((unsigned)NumOpElts, -1);
continue;
}
if (Op.getOpcode() != ISD::EXTRACT_SUBVECTOR)
return SDValue();
// What vector are we extracting the subvector from and at what index?
SDValue ExtVec = Op.getOperand(0);
int ExtIdx = Op.getConstantOperandVal(1);
// We want the EVT of the original extraction to correctly scale the
// extraction index.
EVT ExtVT = ExtVec.getValueType();
ExtVec = peekThroughBitcasts(ExtVec);
// UNDEF nodes convert to UNDEF shuffle mask values.
if (ExtVec.isUndef()) {
Mask.append((unsigned)NumOpElts, -1);
continue;
}
// Ensure that we are extracting a subvector from a vector the same
// size as the result.
if (ExtVT.getSizeInBits() != VT.getSizeInBits())
return SDValue();
// Scale the subvector index to account for any bitcast.
int NumExtElts = ExtVT.getVectorNumElements();
if (0 == (NumExtElts % NumElts))
ExtIdx /= (NumExtElts / NumElts);
else if (0 == (NumElts % NumExtElts))
ExtIdx *= (NumElts / NumExtElts);
else
return SDValue();
// At most we can reference 2 inputs in the final shuffle.
if (SV0.isUndef() || SV0 == ExtVec) {
SV0 = ExtVec;
for (int i = 0; i != NumOpElts; ++i)
Mask.push_back(i + ExtIdx);
} else if (SV1.isUndef() || SV1 == ExtVec) {
SV1 = ExtVec;
for (int i = 0; i != NumOpElts; ++i)
Mask.push_back(i + ExtIdx + NumElts);
} else {
return SDValue();
}
}
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
return TLI.buildLegalVectorShuffle(VT, SDLoc(N), DAG.getBitcast(VT, SV0),
DAG.getBitcast(VT, SV1), Mask, DAG);
}
static SDValue combineConcatVectorOfCasts(SDNode *N, SelectionDAG &DAG) {
unsigned CastOpcode = N->getOperand(0).getOpcode();
switch (CastOpcode) {
case ISD::SINT_TO_FP:
case ISD::UINT_TO_FP:
case ISD::FP_TO_SINT:
case ISD::FP_TO_UINT:
// TODO: Allow more opcodes?
// case ISD::BITCAST:
// case ISD::TRUNCATE:
// case ISD::ZERO_EXTEND:
// case ISD::SIGN_EXTEND:
// case ISD::FP_EXTEND:
break;
default:
return SDValue();
}
EVT SrcVT = N->getOperand(0).getOperand(0).getValueType();
if (!SrcVT.isVector())
return SDValue();
// All operands of the concat must be the same kind of cast from the same
// source type.
SmallVector<SDValue, 4> SrcOps;
for (SDValue Op : N->ops()) {
if (Op.getOpcode() != CastOpcode || !Op.hasOneUse() ||
Op.getOperand(0).getValueType() != SrcVT)
return SDValue();
SrcOps.push_back(Op.getOperand(0));
}
// The wider cast must be supported by the target. This is unusual because
// the operation support type parameter depends on the opcode. In addition,
// check the other type in the cast to make sure this is really legal.
EVT VT = N->getValueType(0);
EVT SrcEltVT = SrcVT.getVectorElementType();
ElementCount NumElts = SrcVT.getVectorElementCount() * N->getNumOperands();
EVT ConcatSrcVT = EVT::getVectorVT(*DAG.getContext(), SrcEltVT, NumElts);
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
switch (CastOpcode) {
case ISD::SINT_TO_FP:
case ISD::UINT_TO_FP:
if (!TLI.isOperationLegalOrCustom(CastOpcode, ConcatSrcVT) ||
!TLI.isTypeLegal(VT))
return SDValue();
break;
case ISD::FP_TO_SINT:
case ISD::FP_TO_UINT:
if (!TLI.isOperationLegalOrCustom(CastOpcode, VT) ||
!TLI.isTypeLegal(ConcatSrcVT))
return SDValue();
break;
default:
llvm_unreachable("Unexpected cast opcode");
}
// concat (cast X), (cast Y)... -> cast (concat X, Y...)
SDLoc DL(N);
SDValue NewConcat = DAG.getNode(ISD::CONCAT_VECTORS, DL, ConcatSrcVT, SrcOps);
return DAG.getNode(CastOpcode, DL, VT, NewConcat);
}
SDValue DAGCombiner::visitCONCAT_VECTORS(SDNode *N) {
// If we only have one input vector, we don't need to do any concatenation.
if (N->getNumOperands() == 1)
return N->getOperand(0);
// Check if all of the operands are undefs.
EVT VT = N->getValueType(0);
if (ISD::allOperandsUndef(N))
return DAG.getUNDEF(VT);
// Optimize concat_vectors where all but the first of the vectors are undef.
if (all_of(drop_begin(N->ops()),
[](const SDValue &Op) { return Op.isUndef(); })) {
SDValue In = N->getOperand(0);
assert(In.getValueType().isVector() && "Must concat vectors");
// If the input is a concat_vectors, just make a larger concat by padding
// with smaller undefs.
if (In.getOpcode() == ISD::CONCAT_VECTORS && In.hasOneUse()) {
unsigned NumOps = N->getNumOperands() * In.getNumOperands();
SmallVector<SDValue, 4> Ops(In->op_begin(), In->op_end());
Ops.resize(NumOps, DAG.getUNDEF(Ops[0].getValueType()));
return DAG.getNode(ISD::CONCAT_VECTORS, SDLoc(N), VT, Ops);
}
SDValue Scalar = peekThroughOneUseBitcasts(In);
// concat_vectors(scalar_to_vector(scalar), undef) ->
// scalar_to_vector(scalar)
if (!LegalOperations && Scalar.getOpcode() == ISD::SCALAR_TO_VECTOR &&
Scalar.hasOneUse()) {
EVT SVT = Scalar.getValueType().getVectorElementType();
if (SVT == Scalar.getOperand(0).getValueType())
Scalar = Scalar.getOperand(0);
}
// concat_vectors(scalar, undef) -> scalar_to_vector(scalar)
if (!Scalar.getValueType().isVector()) {
// If the bitcast type isn't legal, it might be a trunc of a legal type;
// look through the trunc so we can still do the transform:
// concat_vectors(trunc(scalar), undef) -> scalar_to_vector(scalar)
if (Scalar->getOpcode() == ISD::TRUNCATE &&
!TLI.isTypeLegal(Scalar.getValueType()) &&
TLI.isTypeLegal(Scalar->getOperand(0).getValueType()))
Scalar = Scalar->getOperand(0);
EVT SclTy = Scalar.getValueType();
if (!SclTy.isFloatingPoint() && !SclTy.isInteger())
return SDValue();
// Bail out if the vector size is not a multiple of the scalar size.
if (VT.getSizeInBits() % SclTy.getSizeInBits())
return SDValue();
unsigned VNTNumElms = VT.getSizeInBits() / SclTy.getSizeInBits();
if (VNTNumElms < 2)
return SDValue();
EVT NVT = EVT::getVectorVT(*DAG.getContext(), SclTy, VNTNumElms);
if (!TLI.isTypeLegal(NVT) || !TLI.isTypeLegal(Scalar.getValueType()))
return SDValue();
SDValue Res = DAG.getNode(ISD::SCALAR_TO_VECTOR, SDLoc(N), NVT, Scalar);
return DAG.getBitcast(VT, Res);
}
}
// Fold any combination of BUILD_VECTOR or UNDEF nodes into one BUILD_VECTOR.
// We have already tested above for an UNDEF only concatenation.
// fold (concat_vectors (BUILD_VECTOR A, B, ...), (BUILD_VECTOR C, D, ...))
// -> (BUILD_VECTOR A, B, ..., C, D, ...)
auto IsBuildVectorOrUndef = [](const SDValue &Op) {
return ISD::UNDEF == Op.getOpcode() || ISD::BUILD_VECTOR == Op.getOpcode();
};
if (llvm::all_of(N->ops(), IsBuildVectorOrUndef)) {
SmallVector<SDValue, 8> Opnds;
EVT SVT = VT.getScalarType();
EVT MinVT = SVT;
if (!SVT.isFloatingPoint()) {
// If BUILD_VECTOR are from built from integer, they may have different
// operand types. Get the smallest type and truncate all operands to it.
bool FoundMinVT = false;
for (const SDValue &Op : N->ops())
if (ISD::BUILD_VECTOR == Op.getOpcode()) {
EVT OpSVT = Op.getOperand(0).getValueType();
MinVT = (!FoundMinVT || OpSVT.bitsLE(MinVT)) ? OpSVT : MinVT;
FoundMinVT = true;
}
assert(FoundMinVT && "Concat vector type mismatch");
}
for (const SDValue &Op : N->ops()) {
EVT OpVT = Op.getValueType();
unsigned NumElts = OpVT.getVectorNumElements();
if (ISD::UNDEF == Op.getOpcode())
Opnds.append(NumElts, DAG.getUNDEF(MinVT));
if (ISD::BUILD_VECTOR == Op.getOpcode()) {
if (SVT.isFloatingPoint()) {
assert(SVT == OpVT.getScalarType() && "Concat vector type mismatch");
Opnds.append(Op->op_begin(), Op->op_begin() + NumElts);
} else {
for (unsigned i = 0; i != NumElts; ++i)
Opnds.push_back(
DAG.getNode(ISD::TRUNCATE, SDLoc(N), MinVT, Op.getOperand(i)));
}
}
}
assert(VT.getVectorNumElements() == Opnds.size() &&
"Concat vector type mismatch");
return DAG.getBuildVector(VT, SDLoc(N), Opnds);
}
// Fold CONCAT_VECTORS of only bitcast scalars (or undef) to BUILD_VECTOR.
// FIXME: Add support for concat_vectors(bitcast(vec0),bitcast(vec1),...).
if (SDValue V = combineConcatVectorOfScalars(N, DAG))
return V;
if (Level < AfterLegalizeVectorOps && TLI.isTypeLegal(VT)) {
// Fold CONCAT_VECTORS of CONCAT_VECTORS (or undef) to VECTOR_SHUFFLE.
if (SDValue V = combineConcatVectorOfConcatVectors(N, DAG))
return V;
// Fold CONCAT_VECTORS of EXTRACT_SUBVECTOR (or undef) to VECTOR_SHUFFLE.
if (SDValue V = combineConcatVectorOfExtracts(N, DAG))
return V;
}
if (SDValue V = combineConcatVectorOfCasts(N, DAG))
return V;
// Type legalization of vectors and DAG canonicalization of SHUFFLE_VECTOR
// nodes often generate nop CONCAT_VECTOR nodes. Scan the CONCAT_VECTOR
// operands and look for a CONCAT operations that place the incoming vectors
// at the exact same location.
//
// For scalable vectors, EXTRACT_SUBVECTOR indexes are implicitly scaled.
SDValue SingleSource = SDValue();
unsigned PartNumElem =
N->getOperand(0).getValueType().getVectorMinNumElements();
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
SDValue Op = N->getOperand(i);
if (Op.isUndef())
continue;
// Check if this is the identity extract:
if (Op.getOpcode() != ISD::EXTRACT_SUBVECTOR)
return SDValue();
// Find the single incoming vector for the extract_subvector.
if (SingleSource.getNode()) {
if (Op.getOperand(0) != SingleSource)
return SDValue();
} else {
SingleSource = Op.getOperand(0);
// Check the source type is the same as the type of the result.
// If not, this concat may extend the vector, so we can not
// optimize it away.
if (SingleSource.getValueType() != N->getValueType(0))
return SDValue();
}
// Check that we are reading from the identity index.
unsigned IdentityIndex = i * PartNumElem;
if (Op.getConstantOperandAPInt(1) != IdentityIndex)
return SDValue();
}
if (SingleSource.getNode())
return SingleSource;
return SDValue();
}
// Helper that peeks through INSERT_SUBVECTOR/CONCAT_VECTORS to find
// if the subvector can be sourced for free.
static SDValue getSubVectorSrc(SDValue V, SDValue Index, EVT SubVT) {
if (V.getOpcode() == ISD::INSERT_SUBVECTOR &&
V.getOperand(1).getValueType() == SubVT && V.getOperand(2) == Index) {
return V.getOperand(1);
}
auto *IndexC = dyn_cast<ConstantSDNode>(Index);
if (IndexC && V.getOpcode() == ISD::CONCAT_VECTORS &&
V.getOperand(0).getValueType() == SubVT &&
(IndexC->getZExtValue() % SubVT.getVectorMinNumElements()) == 0) {
uint64_t SubIdx = IndexC->getZExtValue() / SubVT.getVectorMinNumElements();
return V.getOperand(SubIdx);
}
return SDValue();
}
static SDValue narrowInsertExtractVectorBinOp(SDNode *Extract,
SelectionDAG &DAG,
bool LegalOperations) {
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
SDValue BinOp = Extract->getOperand(0);
unsigned BinOpcode = BinOp.getOpcode();
if (!TLI.isBinOp(BinOpcode) || BinOp->getNumValues() != 1)
return SDValue();
EVT VecVT = BinOp.getValueType();
SDValue Bop0 = BinOp.getOperand(0), Bop1 = BinOp.getOperand(1);
if (VecVT != Bop0.getValueType() || VecVT != Bop1.getValueType())
return SDValue();
SDValue Index = Extract->getOperand(1);
EVT SubVT = Extract->getValueType(0);
if (!TLI.isOperationLegalOrCustom(BinOpcode, SubVT, LegalOperations))
return SDValue();
SDValue Sub0 = getSubVectorSrc(Bop0, Index, SubVT);
SDValue Sub1 = getSubVectorSrc(Bop1, Index, SubVT);
// TODO: We could handle the case where only 1 operand is being inserted by
// creating an extract of the other operand, but that requires checking
// number of uses and/or costs.
if (!Sub0 || !Sub1)
return SDValue();
// We are inserting both operands of the wide binop only to extract back
// to the narrow vector size. Eliminate all of the insert/extract:
// ext (binop (ins ?, X, Index), (ins ?, Y, Index)), Index --> binop X, Y
return DAG.getNode(BinOpcode, SDLoc(Extract), SubVT, Sub0, Sub1,
BinOp->getFlags());
}
/// If we are extracting a subvector produced by a wide binary operator try
/// to use a narrow binary operator and/or avoid concatenation and extraction.
static SDValue narrowExtractedVectorBinOp(SDNode *Extract, SelectionDAG &DAG,
bool LegalOperations) {
// TODO: Refactor with the caller (visitEXTRACT_SUBVECTOR), so we can share
// some of these bailouts with other transforms.
if (SDValue V = narrowInsertExtractVectorBinOp(Extract, DAG, LegalOperations))
return V;
// The extract index must be a constant, so we can map it to a concat operand.
auto *ExtractIndexC = dyn_cast<ConstantSDNode>(Extract->getOperand(1));
if (!ExtractIndexC)
return SDValue();
// We are looking for an optionally bitcasted wide vector binary operator
// feeding an extract subvector.
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
SDValue BinOp = peekThroughBitcasts(Extract->getOperand(0));
unsigned BOpcode = BinOp.getOpcode();
if (!TLI.isBinOp(BOpcode) || BinOp->getNumValues() != 1)
return SDValue();
// Exclude the fake form of fneg (fsub -0.0, x) because that is likely to be
// reduced to the unary fneg when it is visited, and we probably want to deal
// with fneg in a target-specific way.
if (BOpcode == ISD::FSUB) {
auto *C = isConstOrConstSplatFP(BinOp.getOperand(0), /*AllowUndefs*/ true);
if (C && C->getValueAPF().isNegZero())
return SDValue();
}
// The binop must be a vector type, so we can extract some fraction of it.
EVT WideBVT = BinOp.getValueType();
// The optimisations below currently assume we are dealing with fixed length
// vectors. It is possible to add support for scalable vectors, but at the
// moment we've done no analysis to prove whether they are profitable or not.
if (!WideBVT.isFixedLengthVector())
return SDValue();
EVT VT = Extract->getValueType(0);
unsigned ExtractIndex = ExtractIndexC->getZExtValue();
assert(ExtractIndex % VT.getVectorNumElements() == 0 &&
"Extract index is not a multiple of the vector length.");
// Bail out if this is not a proper multiple width extraction.
unsigned WideWidth = WideBVT.getSizeInBits();
unsigned NarrowWidth = VT.getSizeInBits();
if (WideWidth % NarrowWidth != 0)
return SDValue();
// Bail out if we are extracting a fraction of a single operation. This can
// occur because we potentially looked through a bitcast of the binop.
unsigned NarrowingRatio = WideWidth / NarrowWidth;
unsigned WideNumElts = WideBVT.getVectorNumElements();
if (WideNumElts % NarrowingRatio != 0)
return SDValue();
// Bail out if the target does not support a narrower version of the binop.
EVT NarrowBVT = EVT::getVectorVT(*DAG.getContext(), WideBVT.getScalarType(),
WideNumElts / NarrowingRatio);
if (!TLI.isOperationLegalOrCustomOrPromote(BOpcode, NarrowBVT))
return SDValue();
// If extraction is cheap, we don't need to look at the binop operands
// for concat ops. The narrow binop alone makes this transform profitable.
// We can't just reuse the original extract index operand because we may have
// bitcasted.
unsigned ConcatOpNum = ExtractIndex / VT.getVectorNumElements();
unsigned ExtBOIdx = ConcatOpNum * NarrowBVT.getVectorNumElements();
if (TLI.isExtractSubvectorCheap(NarrowBVT, WideBVT, ExtBOIdx) &&
BinOp.hasOneUse() && Extract->getOperand(0)->hasOneUse()) {
// extract (binop B0, B1), N --> binop (extract B0, N), (extract B1, N)
SDLoc DL(Extract);
SDValue NewExtIndex = DAG.getVectorIdxConstant(ExtBOIdx, DL);
SDValue X = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, NarrowBVT,
BinOp.getOperand(0), NewExtIndex);
SDValue Y = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, NarrowBVT,
BinOp.getOperand(1), NewExtIndex);
SDValue NarrowBinOp =
DAG.getNode(BOpcode, DL, NarrowBVT, X, Y, BinOp->getFlags());
return DAG.getBitcast(VT, NarrowBinOp);
}
// Only handle the case where we are doubling and then halving. A larger ratio
// may require more than two narrow binops to replace the wide binop.
if (NarrowingRatio != 2)
return SDValue();
// TODO: The motivating case for this transform is an x86 AVX1 target. That
// target has temptingly almost legal versions of bitwise logic ops in 256-bit
// flavors, but no other 256-bit integer support. This could be extended to
// handle any binop, but that may require fixing/adding other folds to avoid
// codegen regressions.
if (BOpcode != ISD::AND && BOpcode != ISD::OR && BOpcode != ISD::XOR)
return SDValue();
// We need at least one concatenation operation of a binop operand to make
// this transform worthwhile. The concat must double the input vector sizes.
auto GetSubVector = [ConcatOpNum](SDValue V) -> SDValue {
if (V.getOpcode() == ISD::CONCAT_VECTORS && V.getNumOperands() == 2)
return V.getOperand(ConcatOpNum);
return SDValue();
};
SDValue SubVecL = GetSubVector(peekThroughBitcasts(BinOp.getOperand(0)));
SDValue SubVecR = GetSubVector(peekThroughBitcasts(BinOp.getOperand(1)));
if (SubVecL || SubVecR) {
// If a binop operand was not the result of a concat, we must extract a
// half-sized operand for our new narrow binop:
// extract (binop (concat X1, X2), (concat Y1, Y2)), N --> binop XN, YN
// extract (binop (concat X1, X2), Y), N --> binop XN, (extract Y, IndexC)
// extract (binop X, (concat Y1, Y2)), N --> binop (extract X, IndexC), YN
SDLoc DL(Extract);
SDValue IndexC = DAG.getVectorIdxConstant(ExtBOIdx, DL);
SDValue X = SubVecL ? DAG.getBitcast(NarrowBVT, SubVecL)
: DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, NarrowBVT,
BinOp.getOperand(0), IndexC);
SDValue Y = SubVecR ? DAG.getBitcast(NarrowBVT, SubVecR)
: DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, NarrowBVT,
BinOp.getOperand(1), IndexC);
SDValue NarrowBinOp = DAG.getNode(BOpcode, DL, NarrowBVT, X, Y);
return DAG.getBitcast(VT, NarrowBinOp);
}
return SDValue();
}
/// If we are extracting a subvector from a wide vector load, convert to a
/// narrow load to eliminate the extraction:
/// (extract_subvector (load wide vector)) --> (load narrow vector)
static SDValue narrowExtractedVectorLoad(SDNode *Extract, SelectionDAG &DAG) {
// TODO: Add support for big-endian. The offset calculation must be adjusted.
if (DAG.getDataLayout().isBigEndian())
return SDValue();
auto *Ld = dyn_cast<LoadSDNode>(Extract->getOperand(0));
if (!Ld || Ld->getExtensionType() || !Ld->isSimple())
return SDValue();
// Allow targets to opt-out.
EVT VT = Extract->getValueType(0);
// We can only create byte sized loads.
if (!VT.isByteSized())
return SDValue();
unsigned Index = Extract->getConstantOperandVal(1);
unsigned NumElts = VT.getVectorMinNumElements();
// The definition of EXTRACT_SUBVECTOR states that the index must be a
// multiple of the minimum number of elements in the result type.
assert(Index % NumElts == 0 && "The extract subvector index is not a "
"multiple of the result's element count");
// It's fine to use TypeSize here as we know the offset will not be negative.
TypeSize Offset = VT.getStoreSize() * (Index / NumElts);
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
if (!TLI.shouldReduceLoadWidth(Ld, Ld->getExtensionType(), VT))
return SDValue();
// The narrow load will be offset from the base address of the old load if
// we are extracting from something besides index 0 (little-endian).
SDLoc DL(Extract);
// TODO: Use "BaseIndexOffset" to make this more effective.
SDValue NewAddr = DAG.getMemBasePlusOffset(Ld->getBasePtr(), Offset, DL);
uint64_t StoreSize = MemoryLocation::getSizeOrUnknown(VT.getStoreSize());
MachineFunction &MF = DAG.getMachineFunction();
MachineMemOperand *MMO;
if (Offset.isScalable()) {
MachinePointerInfo MPI =
MachinePointerInfo(Ld->getPointerInfo().getAddrSpace());
MMO = MF.getMachineMemOperand(Ld->getMemOperand(), MPI, StoreSize);
} else
MMO = MF.getMachineMemOperand(Ld->getMemOperand(), Offset.getFixedSize(),
StoreSize);
SDValue NewLd = DAG.getLoad(VT, DL, Ld->getChain(), NewAddr, MMO);
DAG.makeEquivalentMemoryOrdering(Ld, NewLd);
return NewLd;
}
/// Given EXTRACT_SUBVECTOR(VECTOR_SHUFFLE(Op0, Op1, Mask)),
/// try to produce VECTOR_SHUFFLE(EXTRACT_SUBVECTOR(Op?, ?),
/// EXTRACT_SUBVECTOR(Op?, ?),
/// Mask'))
/// iff it is legal and profitable to do so. Notably, the trimmed mask
/// (containing only the elements that are extracted)
/// must reference at most two subvectors.
static SDValue foldExtractSubvectorFromShuffleVector(SDNode *N,
SelectionDAG &DAG,
const TargetLowering &TLI,
bool LegalOperations) {
assert(N->getOpcode() == ISD::EXTRACT_SUBVECTOR &&
"Must only be called on EXTRACT_SUBVECTOR's");
SDValue N0 = N->getOperand(0);
// Only deal with non-scalable vectors.
EVT NarrowVT = N->getValueType(0);
EVT WideVT = N0.getValueType();
if (!NarrowVT.isFixedLengthVector() || !WideVT.isFixedLengthVector())
return SDValue();
// The operand must be a shufflevector.
auto *WideShuffleVector = dyn_cast<ShuffleVectorSDNode>(N0);
if (!WideShuffleVector)
return SDValue();
// The old shuffleneeds to go away.
if (!WideShuffleVector->hasOneUse())
return SDValue();
// And the narrow shufflevector that we'll form must be legal.
if (LegalOperations &&
!TLI.isOperationLegalOrCustom(ISD::VECTOR_SHUFFLE, NarrowVT))
return SDValue();
uint64_t FirstExtractedEltIdx = N->getConstantOperandVal(1);
int NumEltsExtracted = NarrowVT.getVectorNumElements();
assert((FirstExtractedEltIdx % NumEltsExtracted) == 0 &&
"Extract index is not a multiple of the output vector length.");
int WideNumElts = WideVT.getVectorNumElements();
SmallVector<int, 16> NewMask;
NewMask.reserve(NumEltsExtracted);
SmallSetVector<std::pair<SDValue /*Op*/, int /*SubvectorIndex*/>, 2>
DemandedSubvectors;
// Try to decode the wide mask into narrow mask from at most two subvectors.
for (int M : WideShuffleVector->getMask().slice(FirstExtractedEltIdx,
NumEltsExtracted)) {
assert((M >= -1) && (M < (2 * WideNumElts)) &&
"Out-of-bounds shuffle mask?");
if (M < 0) {
// Does not depend on operands, does not require adjustment.
NewMask.emplace_back(M);
continue;
}
// From which operand of the shuffle does this shuffle mask element pick?
int WideShufOpIdx = M / WideNumElts;
// Which element of that operand is picked?
int OpEltIdx = M % WideNumElts;
assert((OpEltIdx + WideShufOpIdx * WideNumElts) == M &&
"Shuffle mask vector decomposition failure.");
// And which NumEltsExtracted-sized subvector of that operand is that?
int OpSubvecIdx = OpEltIdx / NumEltsExtracted;
// And which element within that subvector of that operand is that?
int OpEltIdxInSubvec = OpEltIdx % NumEltsExtracted;
assert((OpEltIdxInSubvec + OpSubvecIdx * NumEltsExtracted) == OpEltIdx &&
"Shuffle mask subvector decomposition failure.");
assert((OpEltIdxInSubvec + OpSubvecIdx * NumEltsExtracted +
WideShufOpIdx * WideNumElts) == M &&
"Shuffle mask full decomposition failure.");
SDValue Op = WideShuffleVector->getOperand(WideShufOpIdx);
if (Op.isUndef()) {
// Picking from an undef operand. Let's adjust mask instead.
NewMask.emplace_back(-1);
continue;
}
// Profitability check: only deal with extractions from the first subvector.
if (OpSubvecIdx != 0)
return SDValue();
const std::pair<SDValue, int> DemandedSubvector =
std::make_pair(Op, OpSubvecIdx);
if (DemandedSubvectors.insert(DemandedSubvector)) {
if (DemandedSubvectors.size() > 2)
return SDValue(); // We can't handle more than two subvectors.
// How many elements into the WideVT does this subvector start?
int Index = NumEltsExtracted * OpSubvecIdx;
// Bail out if the extraction isn't going to be cheap.
if (!TLI.isExtractSubvectorCheap(NarrowVT, WideVT, Index))
return SDValue();
}
// Ok, but from which operand of the new shuffle will this element pick?
int NewOpIdx =
getFirstIndexOf(DemandedSubvectors.getArrayRef(), DemandedSubvector);
assert((NewOpIdx == 0 || NewOpIdx == 1) && "Unexpected operand index.");
int AdjM = OpEltIdxInSubvec + NewOpIdx * NumEltsExtracted;
NewMask.emplace_back(AdjM);
}
assert(NewMask.size() == (unsigned)NumEltsExtracted && "Produced bad mask.");
assert(DemandedSubvectors.size() <= 2 &&
"Should have ended up demanding at most two subvectors.");
// Did we discover that the shuffle does not actually depend on operands?
if (DemandedSubvectors.empty())
return DAG.getUNDEF(NarrowVT);
// We still perform the exact same EXTRACT_SUBVECTOR, just on different
// operand[s]/index[es], so there is no point in checking for it's legality.
// Do not turn a legal shuffle into an illegal one.
if (TLI.isShuffleMaskLegal(WideShuffleVector->getMask(), WideVT) &&
!TLI.isShuffleMaskLegal(NewMask, NarrowVT))
return SDValue();
SDLoc DL(N);
SmallVector<SDValue, 2> NewOps;
for (const std::pair<SDValue /*Op*/, int /*SubvectorIndex*/>
&DemandedSubvector : DemandedSubvectors) {
// How many elements into the WideVT does this subvector start?
int Index = NumEltsExtracted * DemandedSubvector.second;
SDValue IndexC = DAG.getVectorIdxConstant(Index, DL);
NewOps.emplace_back(DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, NarrowVT,
DemandedSubvector.first, IndexC));
}
assert((NewOps.size() == 1 || NewOps.size() == 2) &&
"Should end up with either one or two ops");
// If we ended up with only one operand, pad with an undef.
if (NewOps.size() == 1)
NewOps.emplace_back(DAG.getUNDEF(NarrowVT));
return DAG.getVectorShuffle(NarrowVT, DL, NewOps[0], NewOps[1], NewMask);
}
SDValue DAGCombiner::visitEXTRACT_SUBVECTOR(SDNode *N) {
EVT NVT = N->getValueType(0);
SDValue V = N->getOperand(0);
uint64_t ExtIdx = N->getConstantOperandVal(1);
// Extract from UNDEF is UNDEF.
if (V.isUndef())
return DAG.getUNDEF(NVT);
if (TLI.isOperationLegalOrCustomOrPromote(ISD::LOAD, NVT))
if (SDValue NarrowLoad = narrowExtractedVectorLoad(N, DAG))
return NarrowLoad;
// Combine an extract of an extract into a single extract_subvector.
// ext (ext X, C), 0 --> ext X, C
if (ExtIdx == 0 && V.getOpcode() == ISD::EXTRACT_SUBVECTOR && V.hasOneUse()) {
if (TLI.isExtractSubvectorCheap(NVT, V.getOperand(0).getValueType(),
V.getConstantOperandVal(1)) &&
TLI.isOperationLegalOrCustom(ISD::EXTRACT_SUBVECTOR, NVT)) {
return DAG.getNode(ISD::EXTRACT_SUBVECTOR, SDLoc(N), NVT, V.getOperand(0),
V.getOperand(1));
}
}
// ty1 extract_vector(ty2 splat(V))) -> ty1 splat(V)
if (V.getOpcode() == ISD::SPLAT_VECTOR)
if (DAG.isConstantValueOfAnyType(V.getOperand(0)) || V.hasOneUse())
if (!LegalOperations || TLI.isOperationLegal(ISD::SPLAT_VECTOR, NVT))
return DAG.getSplatVector(NVT, SDLoc(N), V.getOperand(0));
// Try to move vector bitcast after extract_subv by scaling extraction index:
// extract_subv (bitcast X), Index --> bitcast (extract_subv X, Index')
if (V.getOpcode() == ISD::BITCAST &&
V.getOperand(0).getValueType().isVector() &&
(!LegalOperations || TLI.isOperationLegal(ISD::BITCAST, NVT))) {
SDValue SrcOp = V.getOperand(0);
EVT SrcVT = SrcOp.getValueType();
unsigned SrcNumElts = SrcVT.getVectorMinNumElements();
unsigned DestNumElts = V.getValueType().getVectorMinNumElements();
if ((SrcNumElts % DestNumElts) == 0) {
unsigned SrcDestRatio = SrcNumElts / DestNumElts;
ElementCount NewExtEC = NVT.getVectorElementCount() * SrcDestRatio;
EVT NewExtVT = EVT::getVectorVT(*DAG.getContext(), SrcVT.getScalarType(),
NewExtEC);
if (TLI.isOperationLegalOrCustom(ISD::EXTRACT_SUBVECTOR, NewExtVT)) {
SDLoc DL(N);
SDValue NewIndex = DAG.getVectorIdxConstant(ExtIdx * SrcDestRatio, DL);
SDValue NewExtract = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, NewExtVT,
V.getOperand(0), NewIndex);
return DAG.getBitcast(NVT, NewExtract);
}
}
if ((DestNumElts % SrcNumElts) == 0) {
unsigned DestSrcRatio = DestNumElts / SrcNumElts;
if (NVT.getVectorElementCount().isKnownMultipleOf(DestSrcRatio)) {
ElementCount NewExtEC =
NVT.getVectorElementCount().divideCoefficientBy(DestSrcRatio);
EVT ScalarVT = SrcVT.getScalarType();
if ((ExtIdx % DestSrcRatio) == 0) {
SDLoc DL(N);
unsigned IndexValScaled = ExtIdx / DestSrcRatio;
EVT NewExtVT =
EVT::getVectorVT(*DAG.getContext(), ScalarVT, NewExtEC);
if (TLI.isOperationLegalOrCustom(ISD::EXTRACT_SUBVECTOR, NewExtVT)) {
SDValue NewIndex = DAG.getVectorIdxConstant(IndexValScaled, DL);
SDValue NewExtract =
DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, NewExtVT,
V.getOperand(0), NewIndex);
return DAG.getBitcast(NVT, NewExtract);
}
if (NewExtEC.isScalar() &&
TLI.isOperationLegalOrCustom(ISD::EXTRACT_VECTOR_ELT, ScalarVT)) {
SDValue NewIndex = DAG.getVectorIdxConstant(IndexValScaled, DL);
SDValue NewExtract =
DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, ScalarVT,
V.getOperand(0), NewIndex);
return DAG.getBitcast(NVT, NewExtract);
}
}
}
}
}
if (V.getOpcode() == ISD::CONCAT_VECTORS) {
unsigned ExtNumElts = NVT.getVectorMinNumElements();
EVT ConcatSrcVT = V.getOperand(0).getValueType();
assert(ConcatSrcVT.getVectorElementType() == NVT.getVectorElementType() &&
"Concat and extract subvector do not change element type");
assert((ExtIdx % ExtNumElts) == 0 &&
"Extract index is not a multiple of the input vector length.");
unsigned ConcatSrcNumElts = ConcatSrcVT.getVectorMinNumElements();
unsigned ConcatOpIdx = ExtIdx / ConcatSrcNumElts;
// If the concatenated source types match this extract, it's a direct
// simplification:
// extract_subvec (concat V1, V2, ...), i --> Vi
if (NVT.getVectorElementCount() == ConcatSrcVT.getVectorElementCount())
return V.getOperand(ConcatOpIdx);
// If the concatenated source vectors are a multiple length of this extract,
// then extract a fraction of one of those source vectors directly from a
// concat operand. Example:
// v2i8 extract_subvec (v16i8 concat (v8i8 X), (v8i8 Y), 14 -->
// v2i8 extract_subvec v8i8 Y, 6
if (NVT.isFixedLengthVector() && ConcatSrcVT.isFixedLengthVector() &&
ConcatSrcNumElts % ExtNumElts == 0) {
SDLoc DL(N);
unsigned NewExtIdx = ExtIdx - ConcatOpIdx * ConcatSrcNumElts;
assert(NewExtIdx + ExtNumElts <= ConcatSrcNumElts &&
"Trying to extract from >1 concat operand?");
assert(NewExtIdx % ExtNumElts == 0 &&
"Extract index is not a multiple of the input vector length.");
SDValue NewIndexC = DAG.getVectorIdxConstant(NewExtIdx, DL);
return DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, NVT,
V.getOperand(ConcatOpIdx), NewIndexC);
}
}
if (SDValue V =
foldExtractSubvectorFromShuffleVector(N, DAG, TLI, LegalOperations))
return V;
V = peekThroughBitcasts(V);
// If the input is a build vector. Try to make a smaller build vector.
if (V.getOpcode() == ISD::BUILD_VECTOR) {
EVT InVT = V.getValueType();
unsigned ExtractSize = NVT.getSizeInBits();
unsigned EltSize = InVT.getScalarSizeInBits();
// Only do this if we won't split any elements.
if (ExtractSize % EltSize == 0) {
unsigned NumElems = ExtractSize / EltSize;
EVT EltVT = InVT.getVectorElementType();
EVT ExtractVT =
NumElems == 1 ? EltVT
: EVT::getVectorVT(*DAG.getContext(), EltVT, NumElems);
if ((Level < AfterLegalizeDAG ||
(NumElems == 1 ||
TLI.isOperationLegal(ISD::BUILD_VECTOR, ExtractVT))) &&
(!LegalTypes || TLI.isTypeLegal(ExtractVT))) {
unsigned IdxVal = (ExtIdx * NVT.getScalarSizeInBits()) / EltSize;
if (NumElems == 1) {
SDValue Src = V->getOperand(IdxVal);
if (EltVT != Src.getValueType())
Src = DAG.getNode(ISD::TRUNCATE, SDLoc(N), InVT, Src);
return DAG.getBitcast(NVT, Src);
}
// Extract the pieces from the original build_vector.
SDValue BuildVec = DAG.getBuildVector(ExtractVT, SDLoc(N),
V->ops().slice(IdxVal, NumElems));
return DAG.getBitcast(NVT, BuildVec);
}
}
}
if (V.getOpcode() == ISD::INSERT_SUBVECTOR) {
// Handle only simple case where vector being inserted and vector
// being extracted are of same size.
EVT SmallVT = V.getOperand(1).getValueType();
if (!NVT.bitsEq(SmallVT))
return SDValue();
// Combine:
// (extract_subvec (insert_subvec V1, V2, InsIdx), ExtIdx)
// Into:
// indices are equal or bit offsets are equal => V1
// otherwise => (extract_subvec V1, ExtIdx)
uint64_t InsIdx = V.getConstantOperandVal(2);
if (InsIdx * SmallVT.getScalarSizeInBits() ==
ExtIdx * NVT.getScalarSizeInBits()) {
if (LegalOperations && !TLI.isOperationLegal(ISD::BITCAST, NVT))
return SDValue();
return DAG.getBitcast(NVT, V.getOperand(1));
}
return DAG.getNode(
ISD::EXTRACT_SUBVECTOR, SDLoc(N), NVT,
DAG.getBitcast(N->getOperand(0).getValueType(), V.getOperand(0)),
N->getOperand(1));
}
if (SDValue NarrowBOp = narrowExtractedVectorBinOp(N, DAG, LegalOperations))
return NarrowBOp;
if (SimplifyDemandedVectorElts(SDValue(N, 0)))
return SDValue(N, 0);
return SDValue();
}
/// Try to convert a wide shuffle of concatenated vectors into 2 narrow shuffles
/// followed by concatenation. Narrow vector ops may have better performance
/// than wide ops, and this can unlock further narrowing of other vector ops.
/// Targets can invert this transform later if it is not profitable.
static SDValue foldShuffleOfConcatUndefs(ShuffleVectorSDNode *Shuf,
SelectionDAG &DAG) {
SDValue N0 = Shuf->getOperand(0), N1 = Shuf->getOperand(1);
if (N0.getOpcode() != ISD::CONCAT_VECTORS || N0.getNumOperands() != 2 ||
N1.getOpcode() != ISD::CONCAT_VECTORS || N1.getNumOperands() != 2 ||
!N0.getOperand(1).isUndef() || !N1.getOperand(1).isUndef())
return SDValue();
// Split the wide shuffle mask into halves. Any mask element that is accessing
// operand 1 is offset down to account for narrowing of the vectors.
ArrayRef<int> Mask = Shuf->getMask();
EVT VT = Shuf->getValueType(0);
unsigned NumElts = VT.getVectorNumElements();
unsigned HalfNumElts = NumElts / 2;
SmallVector<int, 16> Mask0(HalfNumElts, -1);
SmallVector<int, 16> Mask1(HalfNumElts, -1);
for (unsigned i = 0; i != NumElts; ++i) {
if (Mask[i] == -1)
continue;
// If we reference the upper (undef) subvector then the element is undef.
if ((Mask[i] % NumElts) >= HalfNumElts)
continue;
int M = Mask[i] < (int)NumElts ? Mask[i] : Mask[i] - (int)HalfNumElts;
if (i < HalfNumElts)
Mask0[i] = M;
else
Mask1[i - HalfNumElts] = M;
}
// Ask the target if this is a valid transform.
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
EVT HalfVT = EVT::getVectorVT(*DAG.getContext(), VT.getScalarType(),
HalfNumElts);
if (!TLI.isShuffleMaskLegal(Mask0, HalfVT) ||
!TLI.isShuffleMaskLegal(Mask1, HalfVT))
return SDValue();
// shuffle (concat X, undef), (concat Y, undef), Mask -->
// concat (shuffle X, Y, Mask0), (shuffle X, Y, Mask1)
SDValue X = N0.getOperand(0), Y = N1.getOperand(0);
SDLoc DL(Shuf);
SDValue Shuf0 = DAG.getVectorShuffle(HalfVT, DL, X, Y, Mask0);
SDValue Shuf1 = DAG.getVectorShuffle(HalfVT, DL, X, Y, Mask1);
return DAG.getNode(ISD::CONCAT_VECTORS, DL, VT, Shuf0, Shuf1);
}
// Tries to turn a shuffle of two CONCAT_VECTORS into a single concat,
// or turn a shuffle of a single concat into simpler shuffle then concat.
static SDValue partitionShuffleOfConcats(SDNode *N, SelectionDAG &DAG) {
EVT VT = N->getValueType(0);
unsigned NumElts = VT.getVectorNumElements();
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
ShuffleVectorSDNode *SVN = cast<ShuffleVectorSDNode>(N);
ArrayRef<int> Mask = SVN->getMask();
SmallVector<SDValue, 4> Ops;
EVT ConcatVT = N0.getOperand(0).getValueType();
unsigned NumElemsPerConcat = ConcatVT.getVectorNumElements();
unsigned NumConcats = NumElts / NumElemsPerConcat;
auto IsUndefMaskElt = [](int i) { return i == -1; };
// Special case: shuffle(concat(A,B)) can be more efficiently represented
// as concat(shuffle(A,B),UNDEF) if the shuffle doesn't set any of the high
// half vector elements.
if (NumElemsPerConcat * 2 == NumElts && N1.isUndef() &&
llvm::all_of(Mask.slice(NumElemsPerConcat, NumElemsPerConcat),
IsUndefMaskElt)) {
N0 = DAG.getVectorShuffle(ConcatVT, SDLoc(N), N0.getOperand(0),
N0.getOperand(1),
Mask.slice(0, NumElemsPerConcat));
N1 = DAG.getUNDEF(ConcatVT);
return DAG.getNode(ISD::CONCAT_VECTORS, SDLoc(N), VT, N0, N1);
}
// Look at every vector that's inserted. We're looking for exact
// subvector-sized copies from a concatenated vector
for (unsigned I = 0; I != NumConcats; ++I) {
unsigned Begin = I * NumElemsPerConcat;
ArrayRef<int> SubMask = Mask.slice(Begin, NumElemsPerConcat);
// Make sure we're dealing with a copy.
if (llvm::all_of(SubMask, IsUndefMaskElt)) {
Ops.push_back(DAG.getUNDEF(ConcatVT));
continue;
}
int OpIdx = -1;
for (int i = 0; i != (int)NumElemsPerConcat; ++i) {
if (IsUndefMaskElt(SubMask[i]))
continue;
if ((SubMask[i] % (int)NumElemsPerConcat) != i)
return SDValue();
int EltOpIdx = SubMask[i] / NumElemsPerConcat;
if (0 <= OpIdx && EltOpIdx != OpIdx)
return SDValue();
OpIdx = EltOpIdx;
}
assert(0 <= OpIdx && "Unknown concat_vectors op");
if (OpIdx < (int)N0.getNumOperands())
Ops.push_back(N0.getOperand(OpIdx));
else
Ops.push_back(N1.getOperand(OpIdx - N0.getNumOperands()));
}
return DAG.getNode(ISD::CONCAT_VECTORS, SDLoc(N), VT, Ops);
}
// Attempt to combine a shuffle of 2 inputs of 'scalar sources' -
// BUILD_VECTOR or SCALAR_TO_VECTOR into a single BUILD_VECTOR.
//
// SHUFFLE(BUILD_VECTOR(), BUILD_VECTOR()) -> BUILD_VECTOR() is always
// a simplification in some sense, but it isn't appropriate in general: some
// BUILD_VECTORs are substantially cheaper than others. The general case
// of a BUILD_VECTOR requires inserting each element individually (or
// performing the equivalent in a temporary stack variable). A BUILD_VECTOR of
// all constants is a single constant pool load. A BUILD_VECTOR where each
// element is identical is a splat. A BUILD_VECTOR where most of the operands
// are undef lowers to a small number of element insertions.
//
// To deal with this, we currently use a bunch of mostly arbitrary heuristics.
// We don't fold shuffles where one side is a non-zero constant, and we don't
// fold shuffles if the resulting (non-splat) BUILD_VECTOR would have duplicate
// non-constant operands. This seems to work out reasonably well in practice.
static SDValue combineShuffleOfScalars(ShuffleVectorSDNode *SVN,
SelectionDAG &DAG,
const TargetLowering &TLI) {
EVT VT = SVN->getValueType(0);
unsigned NumElts = VT.getVectorNumElements();
SDValue N0 = SVN->getOperand(0);
SDValue N1 = SVN->getOperand(1);
if (!N0->hasOneUse())
return SDValue();
// If only one of N1,N2 is constant, bail out if it is not ALL_ZEROS as
// discussed above.
if (!N1.isUndef()) {
if (!N1->hasOneUse())
return SDValue();
bool N0AnyConst = isAnyConstantBuildVector(N0);
bool N1AnyConst = isAnyConstantBuildVector(N1);
if (N0AnyConst && !N1AnyConst && !ISD::isBuildVectorAllZeros(N0.getNode()))
return SDValue();
if (!N0AnyConst && N1AnyConst && !ISD::isBuildVectorAllZeros(N1.getNode()))
return SDValue();
}
// If both inputs are splats of the same value then we can safely merge this
// to a single BUILD_VECTOR with undef elements based on the shuffle mask.
bool IsSplat = false;
auto *BV0 = dyn_cast<BuildVectorSDNode>(N0);
auto *BV1 = dyn_cast<BuildVectorSDNode>(N1);
if (BV0 && BV1)
if (SDValue Splat0 = BV0->getSplatValue())
IsSplat = (Splat0 == BV1->getSplatValue());
SmallVector<SDValue, 8> Ops;
SmallSet<SDValue, 16> DuplicateOps;
for (int M : SVN->getMask()) {
SDValue Op = DAG.getUNDEF(VT.getScalarType());
if (M >= 0) {
int Idx = M < (int)NumElts ? M : M - NumElts;
SDValue &S = (M < (int)NumElts ? N0 : N1);
if (S.getOpcode() == ISD::BUILD_VECTOR) {
Op = S.getOperand(Idx);
} else if (S.getOpcode() == ISD::SCALAR_TO_VECTOR) {
SDValue Op0 = S.getOperand(0);
Op = Idx == 0 ? Op0 : DAG.getUNDEF(Op0.getValueType());
} else {
// Operand can't be combined - bail out.
return SDValue();
}
}
// Don't duplicate a non-constant BUILD_VECTOR operand unless we're
// generating a splat; semantically, this is fine, but it's likely to
// generate low-quality code if the target can't reconstruct an appropriate
// shuffle.
if (!Op.isUndef() && !isIntOrFPConstant(Op))
if (!IsSplat && !DuplicateOps.insert(Op).second)
return SDValue();
Ops.push_back(Op);
}
// BUILD_VECTOR requires all inputs to be of the same type, find the
// maximum type and extend them all.
EVT SVT = VT.getScalarType();
if (SVT.isInteger())
for (SDValue &Op : Ops)
SVT = (SVT.bitsLT(Op.getValueType()) ? Op.getValueType() : SVT);
if (SVT != VT.getScalarType())
for (SDValue &Op : Ops)
Op = Op.isUndef() ? DAG.getUNDEF(SVT)
: (TLI.isZExtFree(Op.getValueType(), SVT)
? DAG.getZExtOrTrunc(Op, SDLoc(SVN), SVT)
: DAG.getSExtOrTrunc(Op, SDLoc(SVN), SVT));
return DAG.getBuildVector(VT, SDLoc(SVN), Ops);
}
// Match shuffles that can be converted to any_vector_extend_in_reg.
// This is often generated during legalization.
// e.g. v4i32 <0,u,1,u> -> (v2i64 any_vector_extend_in_reg(v4i32 src))
// TODO Add support for ZERO_EXTEND_VECTOR_INREG when we have a test case.
static SDValue combineShuffleToVectorExtend(ShuffleVectorSDNode *SVN,
SelectionDAG &DAG,
const TargetLowering &TLI,
bool LegalOperations) {
EVT VT = SVN->getValueType(0);
bool IsBigEndian = DAG.getDataLayout().isBigEndian();
// TODO Add support for big-endian when we have a test case.
if (!VT.isInteger() || IsBigEndian)
return SDValue();
unsigned NumElts = VT.getVectorNumElements();
unsigned EltSizeInBits = VT.getScalarSizeInBits();
ArrayRef<int> Mask = SVN->getMask();
SDValue N0 = SVN->getOperand(0);
// shuffle<0,-1,1,-1> == (v2i64 anyextend_vector_inreg(v4i32))
auto isAnyExtend = [&Mask, &NumElts](unsigned Scale) {
for (unsigned i = 0; i != NumElts; ++i) {
if (Mask[i] < 0)
continue;
if ((i % Scale) == 0 && Mask[i] == (int)(i / Scale))
continue;
return false;
}
return true;
};
// Attempt to match a '*_extend_vector_inreg' shuffle, we just search for
// power-of-2 extensions as they are the most likely.
for (unsigned Scale = 2; Scale < NumElts; Scale *= 2) {
// Check for non power of 2 vector sizes
if (NumElts % Scale != 0)
continue;
if (!isAnyExtend(Scale))
continue;
EVT OutSVT = EVT::getIntegerVT(*DAG.getContext(), EltSizeInBits * Scale);
EVT OutVT = EVT::getVectorVT(*DAG.getContext(), OutSVT, NumElts / Scale);
// Never create an illegal type. Only create unsupported operations if we
// are pre-legalization.
if (TLI.isTypeLegal(OutVT))
if (!LegalOperations ||
TLI.isOperationLegalOrCustom(ISD::ANY_EXTEND_VECTOR_INREG, OutVT))
return DAG.getBitcast(VT,
DAG.getNode(ISD::ANY_EXTEND_VECTOR_INREG,
SDLoc(SVN), OutVT, N0));
}
return SDValue();
}
// Detect 'truncate_vector_inreg' style shuffles that pack the lower parts of
// each source element of a large type into the lowest elements of a smaller
// destination type. This is often generated during legalization.
// If the source node itself was a '*_extend_vector_inreg' node then we should
// then be able to remove it.
static SDValue combineTruncationShuffle(ShuffleVectorSDNode *SVN,
SelectionDAG &DAG) {
EVT VT = SVN->getValueType(0);
bool IsBigEndian = DAG.getDataLayout().isBigEndian();
// TODO Add support for big-endian when we have a test case.
if (!VT.isInteger() || IsBigEndian)
return SDValue();
SDValue N0 = peekThroughBitcasts(SVN->getOperand(0));
unsigned Opcode = N0.getOpcode();
if (Opcode != ISD::ANY_EXTEND_VECTOR_INREG &&
Opcode != ISD::SIGN_EXTEND_VECTOR_INREG &&
Opcode != ISD::ZERO_EXTEND_VECTOR_INREG)
return SDValue();
SDValue N00 = N0.getOperand(0);
ArrayRef<int> Mask = SVN->getMask();
unsigned NumElts = VT.getVectorNumElements();
unsigned EltSizeInBits = VT.getScalarSizeInBits();
unsigned ExtSrcSizeInBits = N00.getScalarValueSizeInBits();
unsigned ExtDstSizeInBits = N0.getScalarValueSizeInBits();
if (ExtDstSizeInBits % ExtSrcSizeInBits != 0)
return SDValue();
unsigned ExtScale = ExtDstSizeInBits / ExtSrcSizeInBits;
// (v4i32 truncate_vector_inreg(v2i64)) == shuffle<0,2-1,-1>
// (v8i16 truncate_vector_inreg(v4i32)) == shuffle<0,2,4,6,-1,-1,-1,-1>
// (v8i16 truncate_vector_inreg(v2i64)) == shuffle<0,4,-1,-1,-1,-1,-1,-1>
auto isTruncate = [&Mask, &NumElts](unsigned Scale) {
for (unsigned i = 0; i != NumElts; ++i) {
if (Mask[i] < 0)
continue;
if ((i * Scale) < NumElts && Mask[i] == (int)(i * Scale))
continue;
return false;
}
return true;
};
// At the moment we just handle the case where we've truncated back to the
// same size as before the extension.
// TODO: handle more extension/truncation cases as cases arise.
if (EltSizeInBits != ExtSrcSizeInBits)
return SDValue();
// We can remove *extend_vector_inreg only if the truncation happens at
// the same scale as the extension.
if (isTruncate(ExtScale))
return DAG.getBitcast(VT, N00);
return SDValue();
}
// Combine shuffles of splat-shuffles of the form:
// shuffle (shuffle V, undef, splat-mask), undef, M
// If splat-mask contains undef elements, we need to be careful about
// introducing undef's in the folded mask which are not the result of composing
// the masks of the shuffles.
static SDValue combineShuffleOfSplatVal(ShuffleVectorSDNode *Shuf,
SelectionDAG &DAG) {
if (!Shuf->getOperand(1).isUndef())
return SDValue();
// If the inner operand is a known splat with no undefs, just return that directly.
// TODO: Create DemandedElts mask from Shuf's mask.
// TODO: Allow undef elements and merge with the shuffle code below.
if (DAG.isSplatValue(Shuf->getOperand(0), /*AllowUndefs*/ false))
return Shuf->getOperand(0);
auto *Splat = dyn_cast<ShuffleVectorSDNode>(Shuf->getOperand(0));
if (!Splat || !Splat->isSplat())
return SDValue();
ArrayRef<int> ShufMask = Shuf->getMask();
ArrayRef<int> SplatMask = Splat->getMask();
assert(ShufMask.size() == SplatMask.size() && "Mask length mismatch");
// Prefer simplifying to the splat-shuffle, if possible. This is legal if
// every undef mask element in the splat-shuffle has a corresponding undef
// element in the user-shuffle's mask or if the composition of mask elements
// would result in undef.
// Examples for (shuffle (shuffle v, undef, SplatMask), undef, UserMask):
// * UserMask=[0,2,u,u], SplatMask=[2,u,2,u] -> [2,2,u,u]
// In this case it is not legal to simplify to the splat-shuffle because we
// may be exposing the users of the shuffle an undef element at index 1
// which was not there before the combine.
// * UserMask=[0,u,2,u], SplatMask=[2,u,2,u] -> [2,u,2,u]
// In this case the composition of masks yields SplatMask, so it's ok to
// simplify to the splat-shuffle.
// * UserMask=[3,u,2,u], SplatMask=[2,u,2,u] -> [u,u,2,u]
// In this case the composed mask includes all undef elements of SplatMask
// and in addition sets element zero to undef. It is safe to simplify to
// the splat-shuffle.
auto CanSimplifyToExistingSplat = [](ArrayRef<int> UserMask,
ArrayRef<int> SplatMask) {
for (unsigned i = 0, e = UserMask.size(); i != e; ++i)
if (UserMask[i] != -1 && SplatMask[i] == -1 &&
SplatMask[UserMask[i]] != -1)
return false;
return true;
};
if (CanSimplifyToExistingSplat(ShufMask, SplatMask))
return Shuf->getOperand(0);
// Create a new shuffle with a mask that is composed of the two shuffles'
// masks.
SmallVector<int, 32> NewMask;
for (int Idx : ShufMask)
NewMask.push_back(Idx == -1 ? -1 : SplatMask[Idx]);
return DAG.getVectorShuffle(Splat->getValueType(0), SDLoc(Splat),
Splat->getOperand(0), Splat->getOperand(1),
NewMask);
}
// Combine shuffles of bitcasts into a shuffle of the bitcast type, providing
// the mask can be treated as a larger type.
static SDValue combineShuffleOfBitcast(ShuffleVectorSDNode *SVN,
SelectionDAG &DAG,
const TargetLowering &TLI,
bool LegalOperations) {
SDValue Op0 = SVN->getOperand(0);
SDValue Op1 = SVN->getOperand(1);
EVT VT = SVN->getValueType(0);
if (Op0.getOpcode() != ISD::BITCAST)
return SDValue();
EVT InVT = Op0.getOperand(0).getValueType();
if (!InVT.isVector() ||
(!Op1.isUndef() && (Op1.getOpcode() != ISD::BITCAST ||
Op1.getOperand(0).getValueType() != InVT)))
return SDValue();
if (isAnyConstantBuildVector(Op0.getOperand(0)) &&
(Op1.isUndef() || isAnyConstantBuildVector(Op1.getOperand(0))))
return SDValue();
int VTLanes = VT.getVectorNumElements();
int InLanes = InVT.getVectorNumElements();
if (VTLanes <= InLanes || VTLanes % InLanes != 0 ||
(LegalOperations &&
!TLI.isOperationLegalOrCustom(ISD::VECTOR_SHUFFLE, InVT)))
return SDValue();
int Factor = VTLanes / InLanes;
// Check that each group of lanes in the mask are either undef or make a valid
// mask for the wider lane type.
ArrayRef<int> Mask = SVN->getMask();
SmallVector<int> NewMask;
if (!widenShuffleMaskElts(Factor, Mask, NewMask))
return SDValue();
if (!TLI.isShuffleMaskLegal(NewMask, InVT))
return SDValue();
// Create the new shuffle with the new mask and bitcast it back to the
// original type.
SDLoc DL(SVN);
Op0 = Op0.getOperand(0);
Op1 = Op1.isUndef() ? DAG.getUNDEF(InVT) : Op1.getOperand(0);
SDValue NewShuf = DAG.getVectorShuffle(InVT, DL, Op0, Op1, NewMask);
return DAG.getBitcast(VT, NewShuf);
}
/// Combine shuffle of shuffle of the form:
/// shuf (shuf X, undef, InnerMask), undef, OuterMask --> splat X
static SDValue formSplatFromShuffles(ShuffleVectorSDNode *OuterShuf,
SelectionDAG &DAG) {
if (!OuterShuf->getOperand(1).isUndef())
return SDValue();
auto *InnerShuf = dyn_cast<ShuffleVectorSDNode>(OuterShuf->getOperand(0));
if (!InnerShuf || !InnerShuf->getOperand(1).isUndef())
return SDValue();
ArrayRef<int> OuterMask = OuterShuf->getMask();
ArrayRef<int> InnerMask = InnerShuf->getMask();
unsigned NumElts = OuterMask.size();
assert(NumElts == InnerMask.size() && "Mask length mismatch");
SmallVector<int, 32> CombinedMask(NumElts, -1);
int SplatIndex = -1;
for (unsigned i = 0; i != NumElts; ++i) {
// Undef lanes remain undef.
int OuterMaskElt = OuterMask[i];
if (OuterMaskElt == -1)
continue;
// Peek through the shuffle masks to get the underlying source element.
int InnerMaskElt = InnerMask[OuterMaskElt];
if (InnerMaskElt == -1)
continue;
// Initialize the splatted element.
if (SplatIndex == -1)
SplatIndex = InnerMaskElt;
// Non-matching index - this is not a splat.
if (SplatIndex != InnerMaskElt)
return SDValue();
CombinedMask[i] = InnerMaskElt;
}
assert((all_of(CombinedMask, [](int M) { return M == -1; }) ||
getSplatIndex(CombinedMask) != -1) &&
"Expected a splat mask");
// TODO: The transform may be a win even if the mask is not legal.
EVT VT = OuterShuf->getValueType(0);
assert(VT == InnerShuf->getValueType(0) && "Expected matching shuffle types");
if (!DAG.getTargetLoweringInfo().isShuffleMaskLegal(CombinedMask, VT))
return SDValue();
return DAG.getVectorShuffle(VT, SDLoc(OuterShuf), InnerShuf->getOperand(0),
InnerShuf->getOperand(1), CombinedMask);
}
/// If the shuffle mask is taking exactly one element from the first vector
/// operand and passing through all other elements from the second vector
/// operand, return the index of the mask element that is choosing an element
/// from the first operand. Otherwise, return -1.
static int getShuffleMaskIndexOfOneElementFromOp0IntoOp1(ArrayRef<int> Mask) {
int MaskSize = Mask.size();
int EltFromOp0 = -1;
// TODO: This does not match if there are undef elements in the shuffle mask.
// Should we ignore undefs in the shuffle mask instead? The trade-off is
// removing an instruction (a shuffle), but losing the knowledge that some
// vector lanes are not needed.
for (int i = 0; i != MaskSize; ++i) {
if (Mask[i] >= 0 && Mask[i] < MaskSize) {
// We're looking for a shuffle of exactly one element from operand 0.
if (EltFromOp0 != -1)
return -1;
EltFromOp0 = i;
} else if (Mask[i] != i + MaskSize) {
// Nothing from operand 1 can change lanes.
return -1;
}
}
return EltFromOp0;
}
/// If a shuffle inserts exactly one element from a source vector operand into
/// another vector operand and we can access the specified element as a scalar,
/// then we can eliminate the shuffle.
static SDValue replaceShuffleOfInsert(ShuffleVectorSDNode *Shuf,
SelectionDAG &DAG) {
// First, check if we are taking one element of a vector and shuffling that
// element into another vector.
ArrayRef<int> Mask = Shuf->getMask();
SmallVector<int, 16> CommutedMask(Mask.begin(), Mask.end());
SDValue Op0 = Shuf->getOperand(0);
SDValue Op1 = Shuf->getOperand(1);
int ShufOp0Index = getShuffleMaskIndexOfOneElementFromOp0IntoOp1(Mask);
if (ShufOp0Index == -1) {
// Commute mask and check again.
ShuffleVectorSDNode::commuteMask(CommutedMask);
ShufOp0Index = getShuffleMaskIndexOfOneElementFromOp0IntoOp1(CommutedMask);
if (ShufOp0Index == -1)
return SDValue();
// Commute operands to match the commuted shuffle mask.
std::swap(Op0, Op1);
Mask = CommutedMask;
}
// The shuffle inserts exactly one element from operand 0 into operand 1.
// Now see if we can access that element as a scalar via a real insert element
// instruction.
// TODO: We can try harder to locate the element as a scalar. Examples: it
// could be an operand of SCALAR_TO_VECTOR, BUILD_VECTOR, or a constant.
assert(Mask[ShufOp0Index] >= 0 && Mask[ShufOp0Index] < (int)Mask.size() &&
"Shuffle mask value must be from operand 0");
if (Op0.getOpcode() != ISD::INSERT_VECTOR_ELT)
return SDValue();
auto *InsIndexC = dyn_cast<ConstantSDNode>(Op0.getOperand(2));
if (!InsIndexC || InsIndexC->getSExtValue() != Mask[ShufOp0Index])
return SDValue();
// There's an existing insertelement with constant insertion index, so we
// don't need to check the legality/profitability of a replacement operation
// that differs at most in the constant value. The target should be able to
// lower any of those in a similar way. If not, legalization will expand this
// to a scalar-to-vector plus shuffle.
//
// Note that the shuffle may move the scalar from the position that the insert
// element used. Therefore, our new insert element occurs at the shuffle's
// mask index value, not the insert's index value.
// shuffle (insertelt v1, x, C), v2, mask --> insertelt v2, x, C'
SDValue NewInsIndex = DAG.getVectorIdxConstant(ShufOp0Index, SDLoc(Shuf));
return DAG.getNode(ISD::INSERT_VECTOR_ELT, SDLoc(Shuf), Op0.getValueType(),
Op1, Op0.getOperand(1), NewInsIndex);
}
/// If we have a unary shuffle of a shuffle, see if it can be folded away
/// completely. This has the potential to lose undef knowledge because the first
/// shuffle may not have an undef mask element where the second one does. So
/// only call this after doing simplifications based on demanded elements.
static SDValue simplifyShuffleOfShuffle(ShuffleVectorSDNode *Shuf) {
// shuf (shuf0 X, Y, Mask0), undef, Mask
auto *Shuf0 = dyn_cast<ShuffleVectorSDNode>(Shuf->getOperand(0));
if (!Shuf0 || !Shuf->getOperand(1).isUndef())
return SDValue();
ArrayRef<int> Mask = Shuf->getMask();
ArrayRef<int> Mask0 = Shuf0->getMask();
for (int i = 0, e = (int)Mask.size(); i != e; ++i) {
// Ignore undef elements.
if (Mask[i] == -1)
continue;
assert(Mask[i] >= 0 && Mask[i] < e && "Unexpected shuffle mask value");
// Is the element of the shuffle operand chosen by this shuffle the same as
// the element chosen by the shuffle operand itself?
if (Mask0[Mask[i]] != Mask0[i])
return SDValue();
}
// Every element of this shuffle is identical to the result of the previous
// shuffle, so we can replace this value.
return Shuf->getOperand(0);
}
SDValue DAGCombiner::visitVECTOR_SHUFFLE(SDNode *N) {
EVT VT = N->getValueType(0);
unsigned NumElts = VT.getVectorNumElements();
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
assert(N0.getValueType() == VT && "Vector shuffle must be normalized in DAG");
// Canonicalize shuffle undef, undef -> undef
if (N0.isUndef() && N1.isUndef())
return DAG.getUNDEF(VT);
ShuffleVectorSDNode *SVN = cast<ShuffleVectorSDNode>(N);
// Canonicalize shuffle v, v -> v, undef
if (N0 == N1)
return DAG.getVectorShuffle(VT, SDLoc(N), N0, DAG.getUNDEF(VT),
createUnaryMask(SVN->getMask(), NumElts));
// Canonicalize shuffle undef, v -> v, undef. Commute the shuffle mask.
if (N0.isUndef())
return DAG.getCommutedVectorShuffle(*SVN);
// Remove references to rhs if it is undef
if (N1.isUndef()) {
bool Changed = false;
SmallVector<int, 8> NewMask;
for (unsigned i = 0; i != NumElts; ++i) {
int Idx = SVN->getMaskElt(i);
if (Idx >= (int)NumElts) {
Idx = -1;
Changed = true;
}
NewMask.push_back(Idx);
}
if (Changed)
return DAG.getVectorShuffle(VT, SDLoc(N), N0, N1, NewMask);
}
if (SDValue InsElt = replaceShuffleOfInsert(SVN, DAG))
return InsElt;
// A shuffle of a single vector that is a splatted value can always be folded.
if (SDValue V = combineShuffleOfSplatVal(SVN, DAG))
return V;
if (SDValue V = formSplatFromShuffles(SVN, DAG))
return V;
// If it is a splat, check if the argument vector is another splat or a
// build_vector.
if (SVN->isSplat() && SVN->getSplatIndex() < (int)NumElts) {
int SplatIndex = SVN->getSplatIndex();
if (N0.hasOneUse() && TLI.isExtractVecEltCheap(VT, SplatIndex) &&
TLI.isBinOp(N0.getOpcode()) && N0->getNumValues() == 1) {
// splat (vector_bo L, R), Index -->
// splat (scalar_bo (extelt L, Index), (extelt R, Index))
SDValue L = N0.getOperand(0), R = N0.getOperand(1);
SDLoc DL(N);
EVT EltVT = VT.getScalarType();
SDValue Index = DAG.getVectorIdxConstant(SplatIndex, DL);
SDValue ExtL = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, EltVT, L, Index);
SDValue ExtR = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, EltVT, R, Index);
SDValue NewBO =
DAG.getNode(N0.getOpcode(), DL, EltVT, ExtL, ExtR, N0->getFlags());
SDValue Insert = DAG.getNode(ISD::SCALAR_TO_VECTOR, DL, VT, NewBO);
SmallVector<int, 16> ZeroMask(VT.getVectorNumElements(), 0);
return DAG.getVectorShuffle(VT, DL, Insert, DAG.getUNDEF(VT), ZeroMask);
}
// splat(scalar_to_vector(x), 0) -> build_vector(x,...,x)
// splat(insert_vector_elt(v, x, c), c) -> build_vector(x,...,x)
if ((!LegalOperations || TLI.isOperationLegal(ISD::BUILD_VECTOR, VT)) &&
N0.hasOneUse()) {
if (N0.getOpcode() == ISD::SCALAR_TO_VECTOR && SplatIndex == 0)
return DAG.getSplatBuildVector(VT, SDLoc(N), N0.getOperand(0));
if (N0.getOpcode() == ISD::INSERT_VECTOR_ELT)
if (auto *Idx = dyn_cast<ConstantSDNode>(N0.getOperand(2)))
if (Idx->getAPIntValue() == SplatIndex)
return DAG.getSplatBuildVector(VT, SDLoc(N), N0.getOperand(1));
}
// If this is a bit convert that changes the element type of the vector but
// not the number of vector elements, look through it. Be careful not to
// look though conversions that change things like v4f32 to v2f64.
SDNode *V = N0.getNode();
if (V->getOpcode() == ISD::BITCAST) {
SDValue ConvInput = V->getOperand(0);
if (ConvInput.getValueType().isVector() &&
ConvInput.getValueType().getVectorNumElements() == NumElts)
V = ConvInput.getNode();
}
if (V->getOpcode() == ISD::BUILD_VECTOR) {
assert(V->getNumOperands() == NumElts &&
"BUILD_VECTOR has wrong number of operands");
SDValue Base;
bool AllSame = true;
for (unsigned i = 0; i != NumElts; ++i) {
if (!V->getOperand(i).isUndef()) {
Base = V->getOperand(i);
break;
}
}
// Splat of <u, u, u, u>, return <u, u, u, u>
if (!Base.getNode())
return N0;
for (unsigned i = 0; i != NumElts; ++i) {
if (V->getOperand(i) != Base) {
AllSame = false;
break;
}
}
// Splat of <x, x, x, x>, return <x, x, x, x>
if (AllSame)
return N0;
// Canonicalize any other splat as a build_vector.
SDValue Splatted = V->getOperand(SplatIndex);
SmallVector<SDValue, 8> Ops(NumElts, Splatted);
SDValue NewBV = DAG.getBuildVector(V->getValueType(0), SDLoc(N), Ops);
// We may have jumped through bitcasts, so the type of the
// BUILD_VECTOR may not match the type of the shuffle.
if (V->getValueType(0) != VT)
NewBV = DAG.getBitcast(VT, NewBV);
return NewBV;
}
}
// Simplify source operands based on shuffle mask.
if (SimplifyDemandedVectorElts(SDValue(N, 0)))
return SDValue(N, 0);
// This is intentionally placed after demanded elements simplification because
// it could eliminate knowledge of undef elements created by this shuffle.
if (SDValue ShufOp = simplifyShuffleOfShuffle(SVN))
return ShufOp;
// Match shuffles that can be converted to any_vector_extend_in_reg.
if (SDValue V = combineShuffleToVectorExtend(SVN, DAG, TLI, LegalOperations))
return V;
// Combine "truncate_vector_in_reg" style shuffles.
if (SDValue V = combineTruncationShuffle(SVN, DAG))
return V;
if (N0.getOpcode() == ISD::CONCAT_VECTORS &&
Level < AfterLegalizeVectorOps &&
(N1.isUndef() ||
(N1.getOpcode() == ISD::CONCAT_VECTORS &&
N0.getOperand(0).getValueType() == N1.getOperand(0).getValueType()))) {
if (SDValue V = partitionShuffleOfConcats(N, DAG))
return V;
}
// A shuffle of a concat of the same narrow vector can be reduced to use
// only low-half elements of a concat with undef:
// shuf (concat X, X), undef, Mask --> shuf (concat X, undef), undef, Mask'
if (N0.getOpcode() == ISD::CONCAT_VECTORS && N1.isUndef() &&
N0.getNumOperands() == 2 &&
N0.getOperand(0) == N0.getOperand(1)) {
int HalfNumElts = (int)NumElts / 2;
SmallVector<int, 8> NewMask;
for (unsigned i = 0; i != NumElts; ++i) {
int Idx = SVN->getMaskElt(i);
if (Idx >= HalfNumElts) {
assert(Idx < (int)NumElts && "Shuffle mask chooses undef op");
Idx -= HalfNumElts;
}
NewMask.push_back(Idx);
}
if (TLI.isShuffleMaskLegal(NewMask, VT)) {
SDValue UndefVec = DAG.getUNDEF(N0.getOperand(0).getValueType());
SDValue NewCat = DAG.getNode(ISD::CONCAT_VECTORS, SDLoc(N), VT,
N0.getOperand(0), UndefVec);
return DAG.getVectorShuffle(VT, SDLoc(N), NewCat, N1, NewMask);
}
}
// See if we can replace a shuffle with an insert_subvector.
// e.g. v2i32 into v8i32:
// shuffle(lhs,concat(rhs0,rhs1,rhs2,rhs3),0,1,2,3,10,11,6,7).
// --> insert_subvector(lhs,rhs1,4).
if (Level < AfterLegalizeVectorOps && TLI.isTypeLegal(VT) &&
TLI.isOperationLegalOrCustom(ISD::INSERT_SUBVECTOR, VT)) {
auto ShuffleToInsert = [&](SDValue LHS, SDValue RHS, ArrayRef<int> Mask) {
// Ensure RHS subvectors are legal.
assert(RHS.getOpcode() == ISD::CONCAT_VECTORS && "Can't find subvectors");
EVT SubVT = RHS.getOperand(0).getValueType();
int NumSubVecs = RHS.getNumOperands();
int NumSubElts = SubVT.getVectorNumElements();
assert((NumElts % NumSubElts) == 0 && "Subvector mismatch");
if (!TLI.isTypeLegal(SubVT))
return SDValue();
// Don't bother if we have an unary shuffle (matches undef + LHS elts).
if (all_of(Mask, [NumElts](int M) { return M < (int)NumElts; }))
return SDValue();
// Search [NumSubElts] spans for RHS sequence.
// TODO: Can we avoid nested loops to increase performance?
SmallVector<int> InsertionMask(NumElts);
for (int SubVec = 0; SubVec != NumSubVecs; ++SubVec) {
for (int SubIdx = 0; SubIdx != (int)NumElts; SubIdx += NumSubElts) {
// Reset mask to identity.
std::iota(InsertionMask.begin(), InsertionMask.end(), 0);
// Add subvector insertion.
std::iota(InsertionMask.begin() + SubIdx,
InsertionMask.begin() + SubIdx + NumSubElts,
NumElts + (SubVec * NumSubElts));
// See if the shuffle mask matches the reference insertion mask.
bool MatchingShuffle = true;
for (int i = 0; i != (int)NumElts; ++i) {
int ExpectIdx = InsertionMask[i];
int ActualIdx = Mask[i];
if (0 <= ActualIdx && ExpectIdx != ActualIdx) {
MatchingShuffle = false;
break;
}
}
if (MatchingShuffle)
return DAG.getNode(ISD::INSERT_SUBVECTOR, SDLoc(N), VT, LHS,
RHS.getOperand(SubVec),
DAG.getVectorIdxConstant(SubIdx, SDLoc(N)));
}
}
return SDValue();
};
ArrayRef<int> Mask = SVN->getMask();
if (N1.getOpcode() == ISD::CONCAT_VECTORS)
if (SDValue InsertN1 = ShuffleToInsert(N0, N1, Mask))
return InsertN1;
if (N0.getOpcode() == ISD::CONCAT_VECTORS) {
SmallVector<int> CommuteMask(Mask.begin(), Mask.end());
ShuffleVectorSDNode::commuteMask(CommuteMask);
if (SDValue InsertN0 = ShuffleToInsert(N1, N0, CommuteMask))
return InsertN0;
}
}
// Attempt to combine a shuffle of 2 inputs of 'scalar sources' -
// BUILD_VECTOR or SCALAR_TO_VECTOR into a single BUILD_VECTOR.
if (Level < AfterLegalizeDAG && TLI.isTypeLegal(VT))
if (SDValue Res = combineShuffleOfScalars(SVN, DAG, TLI))
return Res;
// If this shuffle only has a single input that is a bitcasted shuffle,
// attempt to merge the 2 shuffles and suitably bitcast the inputs/output
// back to their original types.
if (N0.getOpcode() == ISD::BITCAST && N0.hasOneUse() &&
N1.isUndef() && Level < AfterLegalizeVectorOps &&
TLI.isTypeLegal(VT)) {
SDValue BC0 = peekThroughOneUseBitcasts(N0);
if (BC0.getOpcode() == ISD::VECTOR_SHUFFLE && BC0.hasOneUse()) {
EVT SVT = VT.getScalarType();
EVT InnerVT = BC0->getValueType(0);
EVT InnerSVT = InnerVT.getScalarType();
// Determine which shuffle works with the smaller scalar type.
EVT ScaleVT = SVT.bitsLT(InnerSVT) ? VT : InnerVT;
EVT ScaleSVT = ScaleVT.getScalarType();
if (TLI.isTypeLegal(ScaleVT) &&
0 == (InnerSVT.getSizeInBits() % ScaleSVT.getSizeInBits()) &&
0 == (SVT.getSizeInBits() % ScaleSVT.getSizeInBits())) {
int InnerScale = InnerSVT.getSizeInBits() / ScaleSVT.getSizeInBits();
int OuterScale = SVT.getSizeInBits() / ScaleSVT.getSizeInBits();
// Scale the shuffle masks to the smaller scalar type.
ShuffleVectorSDNode *InnerSVN = cast<ShuffleVectorSDNode>(BC0);
SmallVector<int, 8> InnerMask;
SmallVector<int, 8> OuterMask;
narrowShuffleMaskElts(InnerScale, InnerSVN->getMask(), InnerMask);
narrowShuffleMaskElts(OuterScale, SVN->getMask(), OuterMask);
// Merge the shuffle masks.
SmallVector<int, 8> NewMask;
for (int M : OuterMask)
NewMask.push_back(M < 0 ? -1 : InnerMask[M]);
// Test for shuffle mask legality over both commutations.
SDValue SV0 = BC0->getOperand(0);
SDValue SV1 = BC0->getOperand(1);
bool LegalMask = TLI.isShuffleMaskLegal(NewMask, ScaleVT);
if (!LegalMask) {
std::swap(SV0, SV1);
ShuffleVectorSDNode::commuteMask(NewMask);
LegalMask = TLI.isShuffleMaskLegal(NewMask, ScaleVT);
}
if (LegalMask) {
SV0 = DAG.getBitcast(ScaleVT, SV0);
SV1 = DAG.getBitcast(ScaleVT, SV1);
return DAG.getBitcast(
VT, DAG.getVectorShuffle(ScaleVT, SDLoc(N), SV0, SV1, NewMask));
}
}
}
}
// Match shuffles of bitcasts, so long as the mask can be treated as the
// larger type.
if (SDValue V = combineShuffleOfBitcast(SVN, DAG, TLI, LegalOperations))
return V;
// Compute the combined shuffle mask for a shuffle with SV0 as the first
// operand, and SV1 as the second operand.
// i.e. Merge SVN(OtherSVN, N1) -> shuffle(SV0, SV1, Mask) iff Commute = false
// Merge SVN(N1, OtherSVN) -> shuffle(SV0, SV1, Mask') iff Commute = true
auto MergeInnerShuffle =
[NumElts, &VT](bool Commute, ShuffleVectorSDNode *SVN,
ShuffleVectorSDNode *OtherSVN, SDValue N1,
const TargetLowering &TLI, SDValue &SV0, SDValue &SV1,
SmallVectorImpl<int> &Mask) -> bool {
// Don't try to fold splats; they're likely to simplify somehow, or they
// might be free.
if (OtherSVN->isSplat())
return false;
SV0 = SV1 = SDValue();
Mask.clear();
for (unsigned i = 0; i != NumElts; ++i) {
int Idx = SVN->getMaskElt(i);
if (Idx < 0) {
// Propagate Undef.
Mask.push_back(Idx);
continue;
}
if (Commute)
Idx = (Idx < (int)NumElts) ? (Idx + NumElts) : (Idx - NumElts);
SDValue CurrentVec;
if (Idx < (int)NumElts) {
// This shuffle index refers to the inner shuffle N0. Lookup the inner
// shuffle mask to identify which vector is actually referenced.
Idx = OtherSVN->getMaskElt(Idx);
if (Idx < 0) {
// Propagate Undef.
Mask.push_back(Idx);
continue;
}
CurrentVec = (Idx < (int)NumElts) ? OtherSVN->getOperand(0)
: OtherSVN->getOperand(1);
} else {
// This shuffle index references an element within N1.
CurrentVec = N1;
}
// Simple case where 'CurrentVec' is UNDEF.
if (CurrentVec.isUndef()) {
Mask.push_back(-1);
continue;
}
// Canonicalize the shuffle index. We don't know yet if CurrentVec
// will be the first or second operand of the combined shuffle.
Idx = Idx % NumElts;
if (!SV0.getNode() || SV0 == CurrentVec) {
// Ok. CurrentVec is the left hand side.
// Update the mask accordingly.
SV0 = CurrentVec;
Mask.push_back(Idx);
continue;
}
if (!SV1.getNode() || SV1 == CurrentVec) {
// Ok. CurrentVec is the right hand side.
// Update the mask accordingly.
SV1 = CurrentVec;
Mask.push_back(Idx + NumElts);
continue;
}
// Last chance - see if the vector is another shuffle and if it
// uses one of the existing candidate shuffle ops.
if (auto *CurrentSVN = dyn_cast<ShuffleVectorSDNode>(CurrentVec)) {
int InnerIdx = CurrentSVN->getMaskElt(Idx);
if (InnerIdx < 0) {
Mask.push_back(-1);
continue;
}
SDValue InnerVec = (InnerIdx < (int)NumElts)
? CurrentSVN->getOperand(0)
: CurrentSVN->getOperand(1);
if (InnerVec.isUndef()) {
Mask.push_back(-1);
continue;
}
InnerIdx %= NumElts;
if (InnerVec == SV0) {
Mask.push_back(InnerIdx);
continue;
}
if (InnerVec == SV1) {
Mask.push_back(InnerIdx + NumElts);
continue;
}
}
// Bail out if we cannot convert the shuffle pair into a single shuffle.
return false;
}
if (llvm::all_of(Mask, [](int M) { return M < 0; }))
return true;
// Avoid introducing shuffles with illegal mask.
// shuffle(shuffle(A, B, M0), C, M1) -> shuffle(A, B, M2)
// shuffle(shuffle(A, B, M0), C, M1) -> shuffle(A, C, M2)
// shuffle(shuffle(A, B, M0), C, M1) -> shuffle(B, C, M2)
// shuffle(shuffle(A, B, M0), C, M1) -> shuffle(B, A, M2)
// shuffle(shuffle(A, B, M0), C, M1) -> shuffle(C, A, M2)
// shuffle(shuffle(A, B, M0), C, M1) -> shuffle(C, B, M2)
if (TLI.isShuffleMaskLegal(Mask, VT))
return true;
std::swap(SV0, SV1);
ShuffleVectorSDNode::commuteMask(Mask);
return TLI.isShuffleMaskLegal(Mask, VT);
};
if (Level < AfterLegalizeDAG && TLI.isTypeLegal(VT)) {
// Canonicalize shuffles according to rules:
// shuffle(A, shuffle(A, B)) -> shuffle(shuffle(A,B), A)
// shuffle(B, shuffle(A, B)) -> shuffle(shuffle(A,B), B)
// shuffle(B, shuffle(A, Undef)) -> shuffle(shuffle(A, Undef), B)
if (N1.getOpcode() == ISD::VECTOR_SHUFFLE &&
N0.getOpcode() != ISD::VECTOR_SHUFFLE) {
// The incoming shuffle must be of the same type as the result of the
// current shuffle.
assert(N1->getOperand(0).getValueType() == VT &&
"Shuffle types don't match");
SDValue SV0 = N1->getOperand(0);
SDValue SV1 = N1->getOperand(1);
bool HasSameOp0 = N0 == SV0;
bool IsSV1Undef = SV1.isUndef();
if (HasSameOp0 || IsSV1Undef || N0 == SV1)
// Commute the operands of this shuffle so merging below will trigger.
return DAG.getCommutedVectorShuffle(*SVN);
}
// Canonicalize splat shuffles to the RHS to improve merging below.
// shuffle(splat(A,u), shuffle(C,D)) -> shuffle'(shuffle(C,D), splat(A,u))
if (N0.getOpcode() == ISD::VECTOR_SHUFFLE &&
N1.getOpcode() == ISD::VECTOR_SHUFFLE &&
cast<ShuffleVectorSDNode>(N0)->isSplat() &&
!cast<ShuffleVectorSDNode>(N1)->isSplat()) {
return DAG.getCommutedVectorShuffle(*SVN);
}
// Try to fold according to rules:
// shuffle(shuffle(A, B, M0), C, M1) -> shuffle(A, B, M2)
// shuffle(shuffle(A, B, M0), C, M1) -> shuffle(A, C, M2)
// shuffle(shuffle(A, B, M0), C, M1) -> shuffle(B, C, M2)
// Don't try to fold shuffles with illegal type.
// Only fold if this shuffle is the only user of the other shuffle.
// Try matching shuffle(C,shuffle(A,B)) commutted patterns as well.
for (int i = 0; i != 2; ++i) {
if (N->getOperand(i).getOpcode() == ISD::VECTOR_SHUFFLE &&
N->isOnlyUserOf(N->getOperand(i).getNode())) {
// The incoming shuffle must be of the same type as the result of the
// current shuffle.
auto *OtherSV = cast<ShuffleVectorSDNode>(N->getOperand(i));
assert(OtherSV->getOperand(0).getValueType() == VT &&
"Shuffle types don't match");
SDValue SV0, SV1;
SmallVector<int, 4> Mask;
if (MergeInnerShuffle(i != 0, SVN, OtherSV, N->getOperand(1 - i), TLI,
SV0, SV1, Mask)) {
// Check if all indices in Mask are Undef. In case, propagate Undef.
if (llvm::all_of(Mask, [](int M) { return M < 0; }))
return DAG.getUNDEF(VT);
return DAG.getVectorShuffle(VT, SDLoc(N),
SV0 ? SV0 : DAG.getUNDEF(VT),
SV1 ? SV1 : DAG.getUNDEF(VT), Mask);
}
}
}
// Merge shuffles through binops if we are able to merge it with at least
// one other shuffles.
// shuffle(bop(shuffle(x,y),shuffle(z,w)),undef)
// shuffle(bop(shuffle(x,y),shuffle(z,w)),bop(shuffle(a,b),shuffle(c,d)))
unsigned SrcOpcode = N0.getOpcode();
if (TLI.isBinOp(SrcOpcode) && N->isOnlyUserOf(N0.getNode()) &&
(N1.isUndef() ||
(SrcOpcode == N1.getOpcode() && N->isOnlyUserOf(N1.getNode())))) {
// Get binop source ops, or just pass on the undef.
SDValue Op00 = N0.getOperand(0);
SDValue Op01 = N0.getOperand(1);
SDValue Op10 = N1.isUndef() ? N1 : N1.getOperand(0);
SDValue Op11 = N1.isUndef() ? N1 : N1.getOperand(1);
// TODO: We might be able to relax the VT check but we don't currently
// have any isBinOp() that has different result/ops VTs so play safe until
// we have test coverage.
if (Op00.getValueType() == VT && Op10.getValueType() == VT &&
Op01.getValueType() == VT && Op11.getValueType() == VT &&
(Op00.getOpcode() == ISD::VECTOR_SHUFFLE ||
Op10.getOpcode() == ISD::VECTOR_SHUFFLE ||
Op01.getOpcode() == ISD::VECTOR_SHUFFLE ||
Op11.getOpcode() == ISD::VECTOR_SHUFFLE)) {
auto CanMergeInnerShuffle = [&](SDValue &SV0, SDValue &SV1,
SmallVectorImpl<int> &Mask, bool LeftOp,
bool Commute) {
SDValue InnerN = Commute ? N1 : N0;
SDValue Op0 = LeftOp ? Op00 : Op01;
SDValue Op1 = LeftOp ? Op10 : Op11;
if (Commute)
std::swap(Op0, Op1);
// Only accept the merged shuffle if we don't introduce undef elements,
// or the inner shuffle already contained undef elements.
auto *SVN0 = dyn_cast<ShuffleVectorSDNode>(Op0);
return SVN0 && InnerN->isOnlyUserOf(SVN0) &&
MergeInnerShuffle(Commute, SVN, SVN0, Op1, TLI, SV0, SV1,
Mask) &&
(llvm::any_of(SVN0->getMask(), [](int M) { return M < 0; }) ||
llvm::none_of(Mask, [](int M) { return M < 0; }));
};
// Ensure we don't increase the number of shuffles - we must merge a
// shuffle from at least one of the LHS and RHS ops.
bool MergedLeft = false;
SDValue LeftSV0, LeftSV1;
SmallVector<int, 4> LeftMask;
if (CanMergeInnerShuffle(LeftSV0, LeftSV1, LeftMask, true, false) ||
CanMergeInnerShuffle(LeftSV0, LeftSV1, LeftMask, true, true)) {
MergedLeft = true;
} else {
LeftMask.assign(SVN->getMask().begin(), SVN->getMask().end());
LeftSV0 = Op00, LeftSV1 = Op10;
}
bool MergedRight = false;
SDValue RightSV0, RightSV1;
SmallVector<int, 4> RightMask;
if (CanMergeInnerShuffle(RightSV0, RightSV1, RightMask, false, false) ||
CanMergeInnerShuffle(RightSV0, RightSV1, RightMask, false, true)) {
MergedRight = true;
} else {
RightMask.assign(SVN->getMask().begin(), SVN->getMask().end());
RightSV0 = Op01, RightSV1 = Op11;
}
if (MergedLeft || MergedRight) {
SDLoc DL(N);
SDValue LHS = DAG.getVectorShuffle(
VT, DL, LeftSV0 ? LeftSV0 : DAG.getUNDEF(VT),
LeftSV1 ? LeftSV1 : DAG.getUNDEF(VT), LeftMask);
SDValue RHS = DAG.getVectorShuffle(
VT, DL, RightSV0 ? RightSV0 : DAG.getUNDEF(VT),
RightSV1 ? RightSV1 : DAG.getUNDEF(VT), RightMask);
return DAG.getNode(SrcOpcode, DL, VT, LHS, RHS);
}
}
}
}
if (SDValue V = foldShuffleOfConcatUndefs(SVN, DAG))
return V;
return SDValue();
}
SDValue DAGCombiner::visitSCALAR_TO_VECTOR(SDNode *N) {
SDValue InVal = N->getOperand(0);
EVT VT = N->getValueType(0);
// Replace a SCALAR_TO_VECTOR(EXTRACT_VECTOR_ELT(V,C0)) pattern
// with a VECTOR_SHUFFLE and possible truncate.
if (InVal.getOpcode() == ISD::EXTRACT_VECTOR_ELT &&
VT.isFixedLengthVector() &&
InVal->getOperand(0).getValueType().isFixedLengthVector()) {
SDValue InVec = InVal->getOperand(0);
SDValue EltNo = InVal->getOperand(1);
auto InVecT = InVec.getValueType();
if (ConstantSDNode *C0 = dyn_cast<ConstantSDNode>(EltNo)) {
SmallVector<int, 8> NewMask(InVecT.getVectorNumElements(), -1);
int Elt = C0->getZExtValue();
NewMask[0] = Elt;
// If we have an implict truncate do truncate here as long as it's legal.
// if it's not legal, this should
if (VT.getScalarType() != InVal.getValueType() &&
InVal.getValueType().isScalarInteger() &&
isTypeLegal(VT.getScalarType())) {
SDValue Val =
DAG.getNode(ISD::TRUNCATE, SDLoc(InVal), VT.getScalarType(), InVal);
return DAG.getNode(ISD::SCALAR_TO_VECTOR, SDLoc(N), VT, Val);
}
if (VT.getScalarType() == InVecT.getScalarType() &&
VT.getVectorNumElements() <= InVecT.getVectorNumElements()) {
SDValue LegalShuffle =
TLI.buildLegalVectorShuffle(InVecT, SDLoc(N), InVec,
DAG.getUNDEF(InVecT), NewMask, DAG);
if (LegalShuffle) {
// If the initial vector is the correct size this shuffle is a
// valid result.
if (VT == InVecT)
return LegalShuffle;
// If not we must truncate the vector.
if (VT.getVectorNumElements() != InVecT.getVectorNumElements()) {
SDValue ZeroIdx = DAG.getVectorIdxConstant(0, SDLoc(N));
EVT SubVT = EVT::getVectorVT(*DAG.getContext(),
InVecT.getVectorElementType(),
VT.getVectorNumElements());
return DAG.getNode(ISD::EXTRACT_SUBVECTOR, SDLoc(N), SubVT,
LegalShuffle, ZeroIdx);
}
}
}
}
}
return SDValue();
}
SDValue DAGCombiner::visitINSERT_SUBVECTOR(SDNode *N) {
EVT VT = N->getValueType(0);
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
uint64_t InsIdx = N->getConstantOperandVal(2);
// If inserting an UNDEF, just return the original vector.
if (N1.isUndef())
return N0;
// If this is an insert of an extracted vector into an undef vector, we can
// just use the input to the extract.
if (N0.isUndef() && N1.getOpcode() == ISD::EXTRACT_SUBVECTOR &&
N1.getOperand(1) == N2 && N1.getOperand(0).getValueType() == VT)
return N1.getOperand(0);
// Simplify scalar inserts into an undef vector:
// insert_subvector undef, (splat X), N2 -> splat X
if (N0.isUndef() && N1.getOpcode() == ISD::SPLAT_VECTOR)
return DAG.getNode(ISD::SPLAT_VECTOR, SDLoc(N), VT, N1.getOperand(0));
// If we are inserting a bitcast value into an undef, with the same
// number of elements, just use the bitcast input of the extract.
// i.e. INSERT_SUBVECTOR UNDEF (BITCAST N1) N2 ->
// BITCAST (INSERT_SUBVECTOR UNDEF N1 N2)
if (N0.isUndef() && N1.getOpcode() == ISD::BITCAST &&
N1.getOperand(0).getOpcode() == ISD::EXTRACT_SUBVECTOR &&
N1.getOperand(0).getOperand(1) == N2 &&
N1.getOperand(0).getOperand(0).getValueType().getVectorElementCount() ==
VT.getVectorElementCount() &&
N1.getOperand(0).getOperand(0).getValueType().getSizeInBits() ==
VT.getSizeInBits()) {
return DAG.getBitcast(VT, N1.getOperand(0).getOperand(0));
}
// If both N1 and N2 are bitcast values on which insert_subvector
// would makes sense, pull the bitcast through.
// i.e. INSERT_SUBVECTOR (BITCAST N0) (BITCAST N1) N2 ->
// BITCAST (INSERT_SUBVECTOR N0 N1 N2)
if (N0.getOpcode() == ISD::BITCAST && N1.getOpcode() == ISD::BITCAST) {
SDValue CN0 = N0.getOperand(0);
SDValue CN1 = N1.getOperand(0);
EVT CN0VT = CN0.getValueType();
EVT CN1VT = CN1.getValueType();
if (CN0VT.isVector() && CN1VT.isVector() &&
CN0VT.getVectorElementType() == CN1VT.getVectorElementType() &&
CN0VT.getVectorElementCount() == VT.getVectorElementCount()) {
SDValue NewINSERT = DAG.getNode(ISD::INSERT_SUBVECTOR, SDLoc(N),
CN0.getValueType(), CN0, CN1, N2);
return DAG.getBitcast(VT, NewINSERT);
}
}
// Combine INSERT_SUBVECTORs where we are inserting to the same index.
// INSERT_SUBVECTOR( INSERT_SUBVECTOR( Vec, SubOld, Idx ), SubNew, Idx )
// --> INSERT_SUBVECTOR( Vec, SubNew, Idx )
if (N0.getOpcode() == ISD::INSERT_SUBVECTOR &&
N0.getOperand(1).getValueType() == N1.getValueType() &&
N0.getOperand(2) == N2)
return DAG.getNode(ISD::INSERT_SUBVECTOR, SDLoc(N), VT, N0.getOperand(0),
N1, N2);
// Eliminate an intermediate insert into an undef vector:
// insert_subvector undef, (insert_subvector undef, X, 0), N2 -->
// insert_subvector undef, X, N2
if (N0.isUndef() && N1.getOpcode() == ISD::INSERT_SUBVECTOR &&
N1.getOperand(0).isUndef() && isNullConstant(N1.getOperand(2)))
return DAG.getNode(ISD::INSERT_SUBVECTOR, SDLoc(N), VT, N0,
N1.getOperand(1), N2);
// Push subvector bitcasts to the output, adjusting the index as we go.
// insert_subvector(bitcast(v), bitcast(s), c1)
// -> bitcast(insert_subvector(v, s, c2))
if ((N0.isUndef() || N0.getOpcode() == ISD::BITCAST) &&
N1.getOpcode() == ISD::BITCAST) {
SDValue N0Src = peekThroughBitcasts(N0);
SDValue N1Src = peekThroughBitcasts(N1);
EVT N0SrcSVT = N0Src.getValueType().getScalarType();
EVT N1SrcSVT = N1Src.getValueType().getScalarType();
if ((N0.isUndef() || N0SrcSVT == N1SrcSVT) &&
N0Src.getValueType().isVector() && N1Src.getValueType().isVector()) {
EVT NewVT;
SDLoc DL(N);
SDValue NewIdx;
LLVMContext &Ctx = *DAG.getContext();
ElementCount NumElts = VT.getVectorElementCount();
unsigned EltSizeInBits = VT.getScalarSizeInBits();
if ((EltSizeInBits % N1SrcSVT.getSizeInBits()) == 0) {
unsigned Scale = EltSizeInBits / N1SrcSVT.getSizeInBits();
NewVT = EVT::getVectorVT(Ctx, N1SrcSVT, NumElts * Scale);
NewIdx = DAG.getVectorIdxConstant(InsIdx * Scale, DL);
} else if ((N1SrcSVT.getSizeInBits() % EltSizeInBits) == 0) {
unsigned Scale = N1SrcSVT.getSizeInBits() / EltSizeInBits;
if (NumElts.isKnownMultipleOf(Scale) && (InsIdx % Scale) == 0) {
NewVT = EVT::getVectorVT(Ctx, N1SrcSVT,
NumElts.divideCoefficientBy(Scale));
NewIdx = DAG.getVectorIdxConstant(InsIdx / Scale, DL);
}
}
if (NewIdx && hasOperation(ISD::INSERT_SUBVECTOR, NewVT)) {
SDValue Res = DAG.getBitcast(NewVT, N0Src);
Res = DAG.getNode(ISD::INSERT_SUBVECTOR, DL, NewVT, Res, N1Src, NewIdx);
return DAG.getBitcast(VT, Res);
}
}
}
// Canonicalize insert_subvector dag nodes.
// Example:
// (insert_subvector (insert_subvector A, Idx0), Idx1)
// -> (insert_subvector (insert_subvector A, Idx1), Idx0)
if (N0.getOpcode() == ISD::INSERT_SUBVECTOR && N0.hasOneUse() &&
N1.getValueType() == N0.getOperand(1).getValueType()) {
unsigned OtherIdx = N0.getConstantOperandVal(2);
if (InsIdx < OtherIdx) {
// Swap nodes.
SDValue NewOp = DAG.getNode(ISD::INSERT_SUBVECTOR, SDLoc(N), VT,
N0.getOperand(0), N1, N2);
AddToWorklist(NewOp.getNode());
return DAG.getNode(ISD::INSERT_SUBVECTOR, SDLoc(N0.getNode()),
VT, NewOp, N0.getOperand(1), N0.getOperand(2));
}
}
// If the input vector is a concatenation, and the insert replaces
// one of the pieces, we can optimize into a single concat_vectors.
if (N0.getOpcode() == ISD::CONCAT_VECTORS && N0.hasOneUse() &&
N0.getOperand(0).getValueType() == N1.getValueType() &&
N0.getOperand(0).getValueType().isScalableVector() ==
N1.getValueType().isScalableVector()) {
unsigned Factor = N1.getValueType().getVectorMinNumElements();
SmallVector<SDValue, 8> Ops(N0->op_begin(), N0->op_end());
Ops[InsIdx / Factor] = N1;
return DAG.getNode(ISD::CONCAT_VECTORS, SDLoc(N), VT, Ops);
}
// Simplify source operands based on insertion.
if (SimplifyDemandedVectorElts(SDValue(N, 0)))
return SDValue(N, 0);
return SDValue();
}
SDValue DAGCombiner::visitFP_TO_FP16(SDNode *N) {
SDValue N0 = N->getOperand(0);
// fold (fp_to_fp16 (fp16_to_fp op)) -> op
if (N0->getOpcode() == ISD::FP16_TO_FP)
return N0->getOperand(0);
return SDValue();
}
SDValue DAGCombiner::visitFP16_TO_FP(SDNode *N) {
SDValue N0 = N->getOperand(0);
// fold fp16_to_fp(op & 0xffff) -> fp16_to_fp(op)
if (!TLI.shouldKeepZExtForFP16Conv() && N0->getOpcode() == ISD::AND) {
ConstantSDNode *AndConst = getAsNonOpaqueConstant(N0.getOperand(1));
if (AndConst && AndConst->getAPIntValue() == 0xffff) {
return DAG.getNode(ISD::FP16_TO_FP, SDLoc(N), N->getValueType(0),
N0.getOperand(0));
}
}
return SDValue();
}
SDValue DAGCombiner::visitFP_TO_BF16(SDNode *N) {
SDValue N0 = N->getOperand(0);
// fold (fp_to_bf16 (bf16_to_fp op)) -> op
if (N0->getOpcode() == ISD::BF16_TO_FP)
return N0->getOperand(0);
return SDValue();
}
SDValue DAGCombiner::visitVECREDUCE(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N0.getValueType();
unsigned Opcode = N->getOpcode();
// VECREDUCE over 1-element vector is just an extract.
if (VT.getVectorElementCount().isScalar()) {
SDLoc dl(N);
SDValue Res =
DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, VT.getVectorElementType(), N0,
DAG.getVectorIdxConstant(0, dl));
if (Res.getValueType() != N->getValueType(0))
Res = DAG.getNode(ISD::ANY_EXTEND, dl, N->getValueType(0), Res);
return Res;
}
// On an boolean vector an and/or reduction is the same as a umin/umax
// reduction. Convert them if the latter is legal while the former isn't.
if (Opcode == ISD::VECREDUCE_AND || Opcode == ISD::VECREDUCE_OR) {
unsigned NewOpcode = Opcode == ISD::VECREDUCE_AND
? ISD::VECREDUCE_UMIN : ISD::VECREDUCE_UMAX;
if (!TLI.isOperationLegalOrCustom(Opcode, VT) &&
TLI.isOperationLegalOrCustom(NewOpcode, VT) &&
DAG.ComputeNumSignBits(N0) == VT.getScalarSizeInBits())
return DAG.getNode(NewOpcode, SDLoc(N), N->getValueType(0), N0);
}
// vecreduce_or(insert_subvector(zero or undef, val)) -> vecreduce_or(val)
// vecreduce_and(insert_subvector(ones or undef, val)) -> vecreduce_and(val)
if (N0.getOpcode() == ISD::INSERT_SUBVECTOR &&
TLI.isTypeLegal(N0.getOperand(1).getValueType())) {
SDValue Vec = N0.getOperand(0);
SDValue Subvec = N0.getOperand(1);
if ((Opcode == ISD::VECREDUCE_OR &&
(N0.getOperand(0).isUndef() || isNullOrNullSplat(Vec))) ||
(Opcode == ISD::VECREDUCE_AND &&
(N0.getOperand(0).isUndef() || isAllOnesOrAllOnesSplat(Vec))))
return DAG.getNode(Opcode, SDLoc(N), N->getValueType(0), Subvec);
}
return SDValue();
}
SDValue DAGCombiner::visitVPOp(SDNode *N) {
// VP operations in which all vector elements are disabled - either by
// determining that the mask is all false or that the EVL is 0 - can be
// eliminated.
bool AreAllEltsDisabled = false;
if (auto EVLIdx = ISD::getVPExplicitVectorLengthIdx(N->getOpcode()))
AreAllEltsDisabled |= isNullConstant(N->getOperand(*EVLIdx));
if (auto MaskIdx = ISD::getVPMaskIdx(N->getOpcode()))
AreAllEltsDisabled |=
ISD::isConstantSplatVectorAllZeros(N->getOperand(*MaskIdx).getNode());
// This is the only generic VP combine we support for now.
if (!AreAllEltsDisabled)
return SDValue();
// Binary operations can be replaced by UNDEF.
if (ISD::isVPBinaryOp(N->getOpcode()))
return DAG.getUNDEF(N->getValueType(0));
// VP Memory operations can be replaced by either the chain (stores) or the
// chain + undef (loads).
if (const auto *MemSD = dyn_cast<MemSDNode>(N)) {
if (MemSD->writeMem())
return MemSD->getChain();
return CombineTo(N, DAG.getUNDEF(N->getValueType(0)), MemSD->getChain());
}
// Reduction operations return the start operand when no elements are active.
if (ISD::isVPReduction(N->getOpcode()))
return N->getOperand(0);
return SDValue();
}
/// Returns a vector_shuffle if it able to transform an AND to a vector_shuffle
/// with the destination vector and a zero vector.
/// e.g. AND V, <0xffffffff, 0, 0xffffffff, 0>. ==>
/// vector_shuffle V, Zero, <0, 4, 2, 4>
SDValue DAGCombiner::XformToShuffleWithZero(SDNode *N) {
assert(N->getOpcode() == ISD::AND && "Unexpected opcode!");
EVT VT = N->getValueType(0);
SDValue LHS = N->getOperand(0);
SDValue RHS = peekThroughBitcasts(N->getOperand(1));
SDLoc DL(N);
// Make sure we're not running after operation legalization where it
// may have custom lowered the vector shuffles.
if (LegalOperations)
return SDValue();
if (RHS.getOpcode() != ISD::BUILD_VECTOR)
return SDValue();
EVT RVT = RHS.getValueType();
unsigned NumElts = RHS.getNumOperands();
// Attempt to create a valid clear mask, splitting the mask into
// sub elements and checking to see if each is
// all zeros or all ones - suitable for shuffle masking.
auto BuildClearMask = [&](int Split) {
int NumSubElts = NumElts * Split;
int NumSubBits = RVT.getScalarSizeInBits() / Split;
SmallVector<int, 8> Indices;
for (int i = 0; i != NumSubElts; ++i) {
int EltIdx = i / Split;
int SubIdx = i % Split;
SDValue Elt = RHS.getOperand(EltIdx);
// X & undef --> 0 (not undef). So this lane must be converted to choose
// from the zero constant vector (same as if the element had all 0-bits).
if (Elt.isUndef()) {
Indices.push_back(i + NumSubElts);
continue;
}
APInt Bits;
if (isa<ConstantSDNode>(Elt))
Bits = cast<ConstantSDNode>(Elt)->getAPIntValue();
else if (isa<ConstantFPSDNode>(Elt))
Bits = cast<ConstantFPSDNode>(Elt)->getValueAPF().bitcastToAPInt();
else
return SDValue();
// Extract the sub element from the constant bit mask.
if (DAG.getDataLayout().isBigEndian())
Bits = Bits.extractBits(NumSubBits, (Split - SubIdx - 1) * NumSubBits);
else
Bits = Bits.extractBits(NumSubBits, SubIdx * NumSubBits);
if (Bits.isAllOnes())
Indices.push_back(i);
else if (Bits == 0)
Indices.push_back(i + NumSubElts);
else
return SDValue();
}
// Let's see if the target supports this vector_shuffle.
EVT ClearSVT = EVT::getIntegerVT(*DAG.getContext(), NumSubBits);
EVT ClearVT = EVT::getVectorVT(*DAG.getContext(), ClearSVT, NumSubElts);
if (!TLI.isVectorClearMaskLegal(Indices, ClearVT))
return SDValue();
SDValue Zero = DAG.getConstant(0, DL, ClearVT);
return DAG.getBitcast(VT, DAG.getVectorShuffle(ClearVT, DL,
DAG.getBitcast(ClearVT, LHS),
Zero, Indices));
};
// Determine maximum split level (byte level masking).
int MaxSplit = 1;
if (RVT.getScalarSizeInBits() % 8 == 0)
MaxSplit = RVT.getScalarSizeInBits() / 8;
for (int Split = 1; Split <= MaxSplit; ++Split)
if (RVT.getScalarSizeInBits() % Split == 0)
if (SDValue S = BuildClearMask(Split))
return S;
return SDValue();
}
/// If a vector binop is performed on splat values, it may be profitable to
/// extract, scalarize, and insert/splat.
static SDValue scalarizeBinOpOfSplats(SDNode *N, SelectionDAG &DAG,
const SDLoc &DL) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
unsigned Opcode = N->getOpcode();
EVT VT = N->getValueType(0);
EVT EltVT = VT.getVectorElementType();
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
// TODO: Remove/replace the extract cost check? If the elements are available
// as scalars, then there may be no extract cost. Should we ask if
// inserting a scalar back into a vector is cheap instead?
int Index0, Index1;
SDValue Src0 = DAG.getSplatSourceVector(N0, Index0);
SDValue Src1 = DAG.getSplatSourceVector(N1, Index1);
if (!Src0 || !Src1 || Index0 != Index1 ||
Src0.getValueType().getVectorElementType() != EltVT ||
Src1.getValueType().getVectorElementType() != EltVT ||
!TLI.isExtractVecEltCheap(VT, Index0) ||
!TLI.isOperationLegalOrCustom(Opcode, EltVT))
return SDValue();
SDValue IndexC = DAG.getVectorIdxConstant(Index0, DL);
SDValue X = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, EltVT, Src0, IndexC);
SDValue Y = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, EltVT, Src1, IndexC);
SDValue ScalarBO = DAG.getNode(Opcode, DL, EltVT, X, Y, N->getFlags());
// If all lanes but 1 are undefined, no need to splat the scalar result.
// TODO: Keep track of undefs and use that info in the general case.
if (N0.getOpcode() == ISD::BUILD_VECTOR && N0.getOpcode() == N1.getOpcode() &&
count_if(N0->ops(), [](SDValue V) { return !V.isUndef(); }) == 1 &&
count_if(N1->ops(), [](SDValue V) { return !V.isUndef(); }) == 1) {
// bo (build_vec ..undef, X, undef...), (build_vec ..undef, Y, undef...) -->
// build_vec ..undef, (bo X, Y), undef...
SmallVector<SDValue, 8> Ops(VT.getVectorNumElements(), DAG.getUNDEF(EltVT));
Ops[Index0] = ScalarBO;
return DAG.getBuildVector(VT, DL, Ops);
}
// bo (splat X, Index), (splat Y, Index) --> splat (bo X, Y), Index
SmallVector<SDValue, 8> Ops(VT.getVectorNumElements(), ScalarBO);
return DAG.getBuildVector(VT, DL, Ops);
}
/// Visit a binary vector operation, like ADD.
SDValue DAGCombiner::SimplifyVBinOp(SDNode *N, const SDLoc &DL) {
EVT VT = N->getValueType(0);
assert(VT.isVector() && "SimplifyVBinOp only works on vectors!");
SDValue LHS = N->getOperand(0);
SDValue RHS = N->getOperand(1);
unsigned Opcode = N->getOpcode();
SDNodeFlags Flags = N->getFlags();
// Move unary shuffles with identical masks after a vector binop:
// VBinOp (shuffle A, Undef, Mask), (shuffle B, Undef, Mask))
// --> shuffle (VBinOp A, B), Undef, Mask
// This does not require type legality checks because we are creating the
// same types of operations that are in the original sequence. We do have to
// restrict ops like integer div that have immediate UB (eg, div-by-zero)
// though. This code is adapted from the identical transform in instcombine.
if (Opcode != ISD::UDIV && Opcode != ISD::SDIV &&
Opcode != ISD::UREM && Opcode != ISD::SREM &&
Opcode != ISD::UDIVREM && Opcode != ISD::SDIVREM) {
auto *Shuf0 = dyn_cast<ShuffleVectorSDNode>(LHS);
auto *Shuf1 = dyn_cast<ShuffleVectorSDNode>(RHS);
if (Shuf0 && Shuf1 && Shuf0->getMask().equals(Shuf1->getMask()) &&
LHS.getOperand(1).isUndef() && RHS.getOperand(1).isUndef() &&
(LHS.hasOneUse() || RHS.hasOneUse() || LHS == RHS)) {
SDValue NewBinOp = DAG.getNode(Opcode, DL, VT, LHS.getOperand(0),
RHS.getOperand(0), Flags);
SDValue UndefV = LHS.getOperand(1);
return DAG.getVectorShuffle(VT, DL, NewBinOp, UndefV, Shuf0->getMask());
}
// Try to sink a splat shuffle after a binop with a uniform constant.
// This is limited to cases where neither the shuffle nor the constant have
// undefined elements because that could be poison-unsafe or inhibit
// demanded elements analysis. It is further limited to not change a splat
// of an inserted scalar because that may be optimized better by
// load-folding or other target-specific behaviors.
if (isConstOrConstSplat(RHS) && Shuf0 && is_splat(Shuf0->getMask()) &&
Shuf0->hasOneUse() && Shuf0->getOperand(1).isUndef() &&
Shuf0->getOperand(0).getOpcode() != ISD::INSERT_VECTOR_ELT) {
// binop (splat X), (splat C) --> splat (binop X, C)
SDValue X = Shuf0->getOperand(0);
SDValue NewBinOp = DAG.getNode(Opcode, DL, VT, X, RHS, Flags);
return DAG.getVectorShuffle(VT, DL, NewBinOp, DAG.getUNDEF(VT),
Shuf0->getMask());
}
if (isConstOrConstSplat(LHS) && Shuf1 && is_splat(Shuf1->getMask()) &&
Shuf1->hasOneUse() && Shuf1->getOperand(1).isUndef() &&
Shuf1->getOperand(0).getOpcode() != ISD::INSERT_VECTOR_ELT) {
// binop (splat C), (splat X) --> splat (binop C, X)
SDValue X = Shuf1->getOperand(0);
SDValue NewBinOp = DAG.getNode(Opcode, DL, VT, LHS, X, Flags);
return DAG.getVectorShuffle(VT, DL, NewBinOp, DAG.getUNDEF(VT),
Shuf1->getMask());
}
}
// The following pattern is likely to emerge with vector reduction ops. Moving
// the binary operation ahead of insertion may allow using a narrower vector
// instruction that has better performance than the wide version of the op:
// VBinOp (ins undef, X, Z), (ins undef, Y, Z) --> ins VecC, (VBinOp X, Y), Z
if (LHS.getOpcode() == ISD::INSERT_SUBVECTOR && LHS.getOperand(0).isUndef() &&
RHS.getOpcode() == ISD::INSERT_SUBVECTOR && RHS.getOperand(0).isUndef() &&
LHS.getOperand(2) == RHS.getOperand(2) &&
(LHS.hasOneUse() || RHS.hasOneUse())) {
SDValue X = LHS.getOperand(1);
SDValue Y = RHS.getOperand(1);
SDValue Z = LHS.getOperand(2);
EVT NarrowVT = X.getValueType();
if (NarrowVT == Y.getValueType() &&
TLI.isOperationLegalOrCustomOrPromote(Opcode, NarrowVT,
LegalOperations)) {
// (binop undef, undef) may not return undef, so compute that result.
SDValue VecC =
DAG.getNode(Opcode, DL, VT, DAG.getUNDEF(VT), DAG.getUNDEF(VT));
SDValue NarrowBO = DAG.getNode(Opcode, DL, NarrowVT, X, Y);
return DAG.getNode(ISD::INSERT_SUBVECTOR, DL, VT, VecC, NarrowBO, Z);
}
}
// Make sure all but the first op are undef or constant.
auto ConcatWithConstantOrUndef = [](SDValue Concat) {
return Concat.getOpcode() == ISD::CONCAT_VECTORS &&
all_of(drop_begin(Concat->ops()), [](const SDValue &Op) {
return Op.isUndef() ||
ISD::isBuildVectorOfConstantSDNodes(Op.getNode());
});
};
// The following pattern is likely to emerge with vector reduction ops. Moving
// the binary operation ahead of the concat may allow using a narrower vector
// instruction that has better performance than the wide version of the op:
// VBinOp (concat X, undef/constant), (concat Y, undef/constant) -->
// concat (VBinOp X, Y), VecC
if (ConcatWithConstantOrUndef(LHS) && ConcatWithConstantOrUndef(RHS) &&
(LHS.hasOneUse() || RHS.hasOneUse())) {
EVT NarrowVT = LHS.getOperand(0).getValueType();
if (NarrowVT == RHS.getOperand(0).getValueType() &&
TLI.isOperationLegalOrCustomOrPromote(Opcode, NarrowVT)) {
unsigned NumOperands = LHS.getNumOperands();
SmallVector<SDValue, 4> ConcatOps;
for (unsigned i = 0; i != NumOperands; ++i) {
// This constant fold for operands 1 and up.
ConcatOps.push_back(DAG.getNode(Opcode, DL, NarrowVT, LHS.getOperand(i),
RHS.getOperand(i)));
}
return DAG.getNode(ISD::CONCAT_VECTORS, DL, VT, ConcatOps);
}
}
if (SDValue V = scalarizeBinOpOfSplats(N, DAG, DL))
return V;
return SDValue();
}
SDValue DAGCombiner::SimplifySelect(const SDLoc &DL, SDValue N0, SDValue N1,
SDValue N2) {
assert(N0.getOpcode() ==ISD::SETCC && "First argument must be a SetCC node!");
SDValue SCC = SimplifySelectCC(DL, N0.getOperand(0), N0.getOperand(1), N1, N2,
cast<CondCodeSDNode>(N0.getOperand(2))->get());
// If we got a simplified select_cc node back from SimplifySelectCC, then
// break it down into a new SETCC node, and a new SELECT node, and then return
// the SELECT node, since we were called with a SELECT node.
if (SCC.getNode()) {
// Check to see if we got a select_cc back (to turn into setcc/select).
// Otherwise, just return whatever node we got back, like fabs.
if (SCC.getOpcode() == ISD::SELECT_CC) {
const SDNodeFlags Flags = N0->getFlags();
SDValue SETCC = DAG.getNode(ISD::SETCC, SDLoc(N0),
N0.getValueType(),
SCC.getOperand(0), SCC.getOperand(1),
SCC.getOperand(4), Flags);
AddToWorklist(SETCC.getNode());
SDValue SelectNode = DAG.getSelect(SDLoc(SCC), SCC.getValueType(), SETCC,
SCC.getOperand(2), SCC.getOperand(3));
SelectNode->setFlags(Flags);
return SelectNode;
}
return SCC;
}
return SDValue();
}
/// Given a SELECT or a SELECT_CC node, where LHS and RHS are the two values
/// being selected between, see if we can simplify the select. Callers of this
/// should assume that TheSelect is deleted if this returns true. As such, they
/// should return the appropriate thing (e.g. the node) back to the top-level of
/// the DAG combiner loop to avoid it being looked at.
bool DAGCombiner::SimplifySelectOps(SDNode *TheSelect, SDValue LHS,
SDValue RHS) {
// fold (select (setcc x, [+-]0.0, *lt), NaN, (fsqrt x))
// The select + setcc is redundant, because fsqrt returns NaN for X < 0.
if (const ConstantFPSDNode *NaN = isConstOrConstSplatFP(LHS)) {
if (NaN->isNaN() && RHS.getOpcode() == ISD::FSQRT) {
// We have: (select (setcc ?, ?, ?), NaN, (fsqrt ?))
SDValue Sqrt = RHS;
ISD::CondCode CC;
SDValue CmpLHS;
const ConstantFPSDNode *Zero = nullptr;
if (TheSelect->getOpcode() == ISD::SELECT_CC) {
CC = cast<CondCodeSDNode>(TheSelect->getOperand(4))->get();
CmpLHS = TheSelect->getOperand(0);
Zero = isConstOrConstSplatFP(TheSelect->getOperand(1));
} else {
// SELECT or VSELECT
SDValue Cmp = TheSelect->getOperand(0);
if (Cmp.getOpcode() == ISD::SETCC) {
CC = cast<CondCodeSDNode>(Cmp.getOperand(2))->get();
CmpLHS = Cmp.getOperand(0);
Zero = isConstOrConstSplatFP(Cmp.getOperand(1));
}
}
if (Zero && Zero->isZero() &&
Sqrt.getOperand(0) == CmpLHS && (CC == ISD::SETOLT ||
CC == ISD::SETULT || CC == ISD::SETLT)) {
// We have: (select (setcc x, [+-]0.0, *lt), NaN, (fsqrt x))
CombineTo(TheSelect, Sqrt);
return true;
}
}
}
// Cannot simplify select with vector condition
if (TheSelect->getOperand(0).getValueType().isVector()) return false;
// If this is a select from two identical things, try to pull the operation
// through the select.
if (LHS.getOpcode() != RHS.getOpcode() ||
!LHS.hasOneUse() || !RHS.hasOneUse())
return false;
// If this is a load and the token chain is identical, replace the select
// of two loads with a load through a select of the address to load from.
// This triggers in things like "select bool X, 10.0, 123.0" after the FP
// constants have been dropped into the constant pool.
if (LHS.getOpcode() == ISD::LOAD) {
LoadSDNode *LLD = cast<LoadSDNode>(LHS);
LoadSDNode *RLD = cast<LoadSDNode>(RHS);
// Token chains must be identical.
if (LHS.getOperand(0) != RHS.getOperand(0) ||
// Do not let this transformation reduce the number of volatile loads.
// Be conservative for atomics for the moment
// TODO: This does appear to be legal for unordered atomics (see D66309)
!LLD->isSimple() || !RLD->isSimple() ||
// FIXME: If either is a pre/post inc/dec load,
// we'd need to split out the address adjustment.
LLD->isIndexed() || RLD->isIndexed() ||
// If this is an EXTLOAD, the VT's must match.
LLD->getMemoryVT() != RLD->getMemoryVT() ||
// If this is an EXTLOAD, the kind of extension must match.
(LLD->getExtensionType() != RLD->getExtensionType() &&
// The only exception is if one of the extensions is anyext.
LLD->getExtensionType() != ISD::EXTLOAD &&
RLD->getExtensionType() != ISD::EXTLOAD) ||
// FIXME: this discards src value information. This is
// over-conservative. It would be beneficial to be able to remember
// both potential memory locations. Since we are discarding
// src value info, don't do the transformation if the memory
// locations are not in the default address space.
LLD->getPointerInfo().getAddrSpace() != 0 ||
RLD->getPointerInfo().getAddrSpace() != 0 ||
// We can't produce a CMOV of a TargetFrameIndex since we won't
// generate the address generation required.
LLD->getBasePtr().getOpcode() == ISD::TargetFrameIndex ||
RLD->getBasePtr().getOpcode() == ISD::TargetFrameIndex ||
!TLI.isOperationLegalOrCustom(TheSelect->getOpcode(),
LLD->getBasePtr().getValueType()))
return false;
// The loads must not depend on one another.
if (LLD->isPredecessorOf(RLD) || RLD->isPredecessorOf(LLD))
return false;
// Check that the select condition doesn't reach either load. If so,
// folding this will induce a cycle into the DAG. If not, this is safe to
// xform, so create a select of the addresses.
SmallPtrSet<const SDNode *, 32> Visited;
SmallVector<const SDNode *, 16> Worklist;
// Always fail if LLD and RLD are not independent. TheSelect is a
// predecessor to all Nodes in question so we need not search past it.
Visited.insert(TheSelect);
Worklist.push_back(LLD);
Worklist.push_back(RLD);
if (SDNode::hasPredecessorHelper(LLD, Visited, Worklist) ||
SDNode::hasPredecessorHelper(RLD, Visited, Worklist))
return false;
SDValue Addr;
if (TheSelect->getOpcode() == ISD::SELECT) {
// We cannot do this optimization if any pair of {RLD, LLD} is a
// predecessor to {RLD, LLD, CondNode}. As we've already compared the
// Loads, we only need to check if CondNode is a successor to one of the
// loads. We can further avoid this if there's no use of their chain
// value.
SDNode *CondNode = TheSelect->getOperand(0).getNode();
Worklist.push_back(CondNode);
if ((LLD->hasAnyUseOfValue(1) &&
SDNode::hasPredecessorHelper(LLD, Visited, Worklist)) ||
(RLD->hasAnyUseOfValue(1) &&
SDNode::hasPredecessorHelper(RLD, Visited, Worklist)))
return false;
Addr = DAG.getSelect(SDLoc(TheSelect),
LLD->getBasePtr().getValueType(),
TheSelect->getOperand(0), LLD->getBasePtr(),
RLD->getBasePtr());
} else { // Otherwise SELECT_CC
// We cannot do this optimization if any pair of {RLD, LLD} is a
// predecessor to {RLD, LLD, CondLHS, CondRHS}. As we've already compared
// the Loads, we only need to check if CondLHS/CondRHS is a successor to
// one of the loads. We can further avoid this if there's no use of their
// chain value.
SDNode *CondLHS = TheSelect->getOperand(0).getNode();
SDNode *CondRHS = TheSelect->getOperand(1).getNode();
Worklist.push_back(CondLHS);
Worklist.push_back(CondRHS);
if ((LLD->hasAnyUseOfValue(1) &&
SDNode::hasPredecessorHelper(LLD, Visited, Worklist)) ||
(RLD->hasAnyUseOfValue(1) &&
SDNode::hasPredecessorHelper(RLD, Visited, Worklist)))
return false;
Addr = DAG.getNode(ISD::SELECT_CC, SDLoc(TheSelect),
LLD->getBasePtr().getValueType(),
TheSelect->getOperand(0),
TheSelect->getOperand(1),
LLD->getBasePtr(), RLD->getBasePtr(),
TheSelect->getOperand(4));
}
SDValue Load;
// It is safe to replace the two loads if they have different alignments,
// but the new load must be the minimum (most restrictive) alignment of the
// inputs.
Align Alignment = std::min(LLD->getAlign(), RLD->getAlign());
MachineMemOperand::Flags MMOFlags = LLD->getMemOperand()->getFlags();
if (!RLD->isInvariant())
MMOFlags &= ~MachineMemOperand::MOInvariant;
if (!RLD->isDereferenceable())
MMOFlags &= ~MachineMemOperand::MODereferenceable;
if (LLD->getExtensionType() == ISD::NON_EXTLOAD) {
// FIXME: Discards pointer and AA info.
Load = DAG.getLoad(TheSelect->getValueType(0), SDLoc(TheSelect),
LLD->getChain(), Addr, MachinePointerInfo(), Alignment,
MMOFlags);
} else {
// FIXME: Discards pointer and AA info.
Load = DAG.getExtLoad(
LLD->getExtensionType() == ISD::EXTLOAD ? RLD->getExtensionType()
: LLD->getExtensionType(),
SDLoc(TheSelect), TheSelect->getValueType(0), LLD->getChain(), Addr,
MachinePointerInfo(), LLD->getMemoryVT(), Alignment, MMOFlags);
}
// Users of the select now use the result of the load.
CombineTo(TheSelect, Load);
// Users of the old loads now use the new load's chain. We know the
// old-load value is dead now.
CombineTo(LHS.getNode(), Load.getValue(0), Load.getValue(1));
CombineTo(RHS.getNode(), Load.getValue(0), Load.getValue(1));
return true;
}
return false;
}
/// Try to fold an expression of the form (N0 cond N1) ? N2 : N3 to a shift and
/// bitwise 'and'.
SDValue DAGCombiner::foldSelectCCToShiftAnd(const SDLoc &DL, SDValue N0,
SDValue N1, SDValue N2, SDValue N3,
ISD::CondCode CC) {
// If this is a select where the false operand is zero and the compare is a
// check of the sign bit, see if we can perform the "gzip trick":
// select_cc setlt X, 0, A, 0 -> and (sra X, size(X)-1), A
// select_cc setgt X, 0, A, 0 -> and (not (sra X, size(X)-1)), A
EVT XType = N0.getValueType();
EVT AType = N2.getValueType();
if (!isNullConstant(N3) || !XType.bitsGE(AType))
return SDValue();
// If the comparison is testing for a positive value, we have to invert
// the sign bit mask, so only do that transform if the target has a bitwise
// 'and not' instruction (the invert is free).
if (CC == ISD::SETGT && TLI.hasAndNot(N2)) {
// (X > -1) ? A : 0
// (X > 0) ? X : 0 <-- This is canonical signed max.
if (!(isAllOnesConstant(N1) || (isNullConstant(N1) && N0 == N2)))
return SDValue();
} else if (CC == ISD::SETLT) {
// (X < 0) ? A : 0
// (X < 1) ? X : 0 <-- This is un-canonicalized signed min.
if (!(isNullConstant(N1) || (isOneConstant(N1) && N0 == N2)))
return SDValue();
} else {
return SDValue();
}
// and (sra X, size(X)-1), A -> "and (srl X, C2), A" iff A is a single-bit
// constant.
EVT ShiftAmtTy = getShiftAmountTy(N0.getValueType());
auto *N2C = dyn_cast<ConstantSDNode>(N2.getNode());
if (N2C && ((N2C->getAPIntValue() & (N2C->getAPIntValue() - 1)) == 0)) {
unsigned ShCt = XType.getSizeInBits() - N2C->getAPIntValue().logBase2() - 1;
if (!TLI.shouldAvoidTransformToShift(XType, ShCt)) {
SDValue ShiftAmt = DAG.getConstant(ShCt, DL, ShiftAmtTy);
SDValue Shift = DAG.getNode(ISD::SRL, DL, XType, N0, ShiftAmt);
AddToWorklist(Shift.getNode());
if (XType.bitsGT(AType)) {
Shift = DAG.getNode(ISD::TRUNCATE, DL, AType, Shift);
AddToWorklist(Shift.getNode());
}
if (CC == ISD::SETGT)
Shift = DAG.getNOT(DL, Shift, AType);
return DAG.getNode(ISD::AND, DL, AType, Shift, N2);
}
}
unsigned ShCt = XType.getSizeInBits() - 1;
if (TLI.shouldAvoidTransformToShift(XType, ShCt))
return SDValue();
SDValue ShiftAmt = DAG.getConstant(ShCt, DL, ShiftAmtTy);
SDValue Shift = DAG.getNode(ISD::SRA, DL, XType, N0, ShiftAmt);
AddToWorklist(Shift.getNode());
if (XType.bitsGT(AType)) {
Shift = DAG.getNode(ISD::TRUNCATE, DL, AType, Shift);
AddToWorklist(Shift.getNode());
}
if (CC == ISD::SETGT)
Shift = DAG.getNOT(DL, Shift, AType);
return DAG.getNode(ISD::AND, DL, AType, Shift, N2);
}
// Fold select(cc, binop(), binop()) -> binop(select(), select()) etc.
SDValue DAGCombiner::foldSelectOfBinops(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
SDValue N2 = N->getOperand(2);
EVT VT = N->getValueType(0);
SDLoc DL(N);
unsigned BinOpc = N1.getOpcode();
if (!TLI.isBinOp(BinOpc) || (N2.getOpcode() != BinOpc))
return SDValue();
// The use checks are intentionally on SDNode because we may be dealing
// with opcodes that produce more than one SDValue.
// TODO: Do we really need to check N0 (the condition operand of the select)?
// But removing that clause could cause an infinite loop...
if (!N0->hasOneUse() || !N1->hasOneUse() || !N2->hasOneUse())
return SDValue();
// Binops may include opcodes that return multiple values, so all values
// must be created/propagated from the newly created binops below.
SDVTList OpVTs = N1->getVTList();
// Fold select(cond, binop(x, y), binop(z, y))
// --> binop(select(cond, x, z), y)
if (N1.getOperand(1) == N2.getOperand(1)) {
SDValue NewSel =
DAG.getSelect(DL, VT, N0, N1.getOperand(0), N2.getOperand(0));
SDValue NewBinOp = DAG.getNode(BinOpc, DL, OpVTs, NewSel, N1.getOperand(1));
NewBinOp->setFlags(N1->getFlags());
NewBinOp->intersectFlagsWith(N2->getFlags());
return NewBinOp;
}
// Fold select(cond, binop(x, y), binop(x, z))
// --> binop(x, select(cond, y, z))
// Second op VT might be different (e.g. shift amount type)
if (N1.getOperand(0) == N2.getOperand(0) &&
VT == N1.getOperand(1).getValueType() &&
VT == N2.getOperand(1).getValueType()) {
SDValue NewSel =
DAG.getSelect(DL, VT, N0, N1.getOperand(1), N2.getOperand(1));
SDValue NewBinOp = DAG.getNode(BinOpc, DL, OpVTs, N1.getOperand(0), NewSel);
NewBinOp->setFlags(N1->getFlags());
NewBinOp->intersectFlagsWith(N2->getFlags());
return NewBinOp;
}
// TODO: Handle isCommutativeBinOp patterns as well?
return SDValue();
}
// Transform (fneg/fabs (bitconvert x)) to avoid loading constant pool values.
SDValue DAGCombiner::foldSignChangeInBitcast(SDNode *N) {
SDValue N0 = N->getOperand(0);
EVT VT = N->getValueType(0);
bool IsFabs = N->getOpcode() == ISD::FABS;
bool IsFree = IsFabs ? TLI.isFAbsFree(VT) : TLI.isFNegFree(VT);
if (IsFree || N0.getOpcode() != ISD::BITCAST || !N0.hasOneUse())
return SDValue();
SDValue Int = N0.getOperand(0);
EVT IntVT = Int.getValueType();
// The operand to cast should be integer.
if (!IntVT.isInteger() || IntVT.isVector())
return SDValue();
// (fneg (bitconvert x)) -> (bitconvert (xor x sign))
// (fabs (bitconvert x)) -> (bitconvert (and x ~sign))
APInt SignMask;
if (N0.getValueType().isVector()) {
// For vector, create a sign mask (0x80...) or its inverse (for fabs,
// 0x7f...) per element and splat it.
SignMask = APInt::getSignMask(N0.getScalarValueSizeInBits());
if (IsFabs)
SignMask = ~SignMask;
SignMask = APInt::getSplat(IntVT.getSizeInBits(), SignMask);
} else {
// For scalar, just use the sign mask (0x80... or the inverse, 0x7f...)
SignMask = APInt::getSignMask(IntVT.getSizeInBits());
if (IsFabs)
SignMask = ~SignMask;
}
SDLoc DL(N0);
Int = DAG.getNode(IsFabs ? ISD::AND : ISD::XOR, DL, IntVT, Int,
DAG.getConstant(SignMask, DL, IntVT));
AddToWorklist(Int.getNode());
return DAG.getBitcast(VT, Int);
}
/// Turn "(a cond b) ? 1.0f : 2.0f" into "load (tmp + ((a cond b) ? 0 : 4)"
/// where "tmp" is a constant pool entry containing an array with 1.0 and 2.0
/// in it. This may be a win when the constant is not otherwise available
/// because it replaces two constant pool loads with one.
SDValue DAGCombiner::convertSelectOfFPConstantsToLoadOffset(
const SDLoc &DL, SDValue N0, SDValue N1, SDValue N2, SDValue N3,
ISD::CondCode CC) {
if (!TLI.reduceSelectOfFPConstantLoads(N0.getValueType()))
return SDValue();
// If we are before legalize types, we want the other legalization to happen
// first (for example, to avoid messing with soft float).
auto *TV = dyn_cast<ConstantFPSDNode>(N2);
auto *FV = dyn_cast<ConstantFPSDNode>(N3);
EVT VT = N2.getValueType();
if (!TV || !FV || !TLI.isTypeLegal(VT))
return SDValue();
// If a constant can be materialized without loads, this does not make sense.
if (TLI.getOperationAction(ISD::ConstantFP, VT) == TargetLowering::Legal ||
TLI.isFPImmLegal(TV->getValueAPF(), TV->getValueType(0), ForCodeSize) ||
TLI.isFPImmLegal(FV->getValueAPF(), FV->getValueType(0), ForCodeSize))
return SDValue();
// If both constants have multiple uses, then we won't need to do an extra
// load. The values are likely around in registers for other users.
if (!TV->hasOneUse() && !FV->hasOneUse())
return SDValue();
Constant *Elts[] = { const_cast<ConstantFP*>(FV->getConstantFPValue()),
const_cast<ConstantFP*>(TV->getConstantFPValue()) };
Type *FPTy = Elts[0]->getType();
const DataLayout &TD = DAG.getDataLayout();
// Create a ConstantArray of the two constants.
Constant *CA = ConstantArray::get(ArrayType::get(FPTy, 2), Elts);
SDValue CPIdx = DAG.getConstantPool(CA, TLI.getPointerTy(DAG.getDataLayout()),
TD.getPrefTypeAlign(FPTy));
Align Alignment = cast<ConstantPoolSDNode>(CPIdx)->getAlign();
// Get offsets to the 0 and 1 elements of the array, so we can select between
// them.
SDValue Zero = DAG.getIntPtrConstant(0, DL);
unsigned EltSize = (unsigned)TD.getTypeAllocSize(Elts[0]->getType());
SDValue One = DAG.getIntPtrConstant(EltSize, SDLoc(FV));
SDValue Cond =
DAG.getSetCC(DL, getSetCCResultType(N0.getValueType()), N0, N1, CC);
AddToWorklist(Cond.getNode());
SDValue CstOffset = DAG.getSelect(DL, Zero.getValueType(), Cond, One, Zero);
AddToWorklist(CstOffset.getNode());
CPIdx = DAG.getNode(ISD::ADD, DL, CPIdx.getValueType(), CPIdx, CstOffset);
AddToWorklist(CPIdx.getNode());
return DAG.getLoad(TV->getValueType(0), DL, DAG.getEntryNode(), CPIdx,
MachinePointerInfo::getConstantPool(
DAG.getMachineFunction()), Alignment);
}
/// Simplify an expression of the form (N0 cond N1) ? N2 : N3
/// where 'cond' is the comparison specified by CC.
SDValue DAGCombiner::SimplifySelectCC(const SDLoc &DL, SDValue N0, SDValue N1,
SDValue N2, SDValue N3, ISD::CondCode CC,
bool NotExtCompare) {
// (x ? y : y) -> y.
if (N2 == N3) return N2;
EVT CmpOpVT = N0.getValueType();
EVT CmpResVT = getSetCCResultType(CmpOpVT);
EVT VT = N2.getValueType();
auto *N1C = dyn_cast<ConstantSDNode>(N1.getNode());
auto *N2C = dyn_cast<ConstantSDNode>(N2.getNode());
auto *N3C = dyn_cast<ConstantSDNode>(N3.getNode());
// Determine if the condition we're dealing with is constant.
if (SDValue SCC = DAG.FoldSetCC(CmpResVT, N0, N1, CC, DL)) {
AddToWorklist(SCC.getNode());
if (auto *SCCC = dyn_cast<ConstantSDNode>(SCC)) {
// fold select_cc true, x, y -> x
// fold select_cc false, x, y -> y
return !(SCCC->isZero()) ? N2 : N3;
}
}
if (SDValue V =
convertSelectOfFPConstantsToLoadOffset(DL, N0, N1, N2, N3, CC))
return V;
if (SDValue V = foldSelectCCToShiftAnd(DL, N0, N1, N2, N3, CC))
return V;
// fold (select_cc seteq (and x, y), 0, 0, A) -> (and (shr (shl x)) A)
// where y is has a single bit set.
// A plaintext description would be, we can turn the SELECT_CC into an AND
// when the condition can be materialized as an all-ones register. Any
// single bit-test can be materialized as an all-ones register with
// shift-left and shift-right-arith.
if (CC == ISD::SETEQ && N0->getOpcode() == ISD::AND &&
N0->getValueType(0) == VT && isNullConstant(N1) && isNullConstant(N2)) {
SDValue AndLHS = N0->getOperand(0);
auto *ConstAndRHS = dyn_cast<ConstantSDNode>(N0->getOperand(1));
if (ConstAndRHS && ConstAndRHS->getAPIntValue().countPopulation() == 1) {
// Shift the tested bit over the sign bit.
const APInt &AndMask = ConstAndRHS->getAPIntValue();
unsigned ShCt = AndMask.getBitWidth() - 1;
if (!TLI.shouldAvoidTransformToShift(VT, ShCt)) {
SDValue ShlAmt =
DAG.getConstant(AndMask.countLeadingZeros(), SDLoc(AndLHS),
getShiftAmountTy(AndLHS.getValueType()));
SDValue Shl = DAG.getNode(ISD::SHL, SDLoc(N0), VT, AndLHS, ShlAmt);
// Now arithmetic right shift it all the way over, so the result is
// either all-ones, or zero.
SDValue ShrAmt =
DAG.getConstant(ShCt, SDLoc(Shl),
getShiftAmountTy(Shl.getValueType()));
SDValue Shr = DAG.getNode(ISD::SRA, SDLoc(N0), VT, Shl, ShrAmt);
return DAG.getNode(ISD::AND, DL, VT, Shr, N3);
}
}
}
// fold select C, 16, 0 -> shl C, 4
bool Fold = N2C && isNullConstant(N3) && N2C->getAPIntValue().isPowerOf2();
bool Swap = N3C && isNullConstant(N2) && N3C->getAPIntValue().isPowerOf2();
if ((Fold || Swap) &&
TLI.getBooleanContents(CmpOpVT) ==
TargetLowering::ZeroOrOneBooleanContent &&
(!LegalOperations || TLI.isOperationLegal(ISD::SETCC, CmpOpVT))) {
if (Swap) {
CC = ISD::getSetCCInverse(CC, CmpOpVT);
std::swap(N2C, N3C);
}
// If the caller doesn't want us to simplify this into a zext of a compare,
// don't do it.
if (NotExtCompare && N2C->isOne())
return SDValue();
SDValue Temp, SCC;
// zext (setcc n0, n1)
if (LegalTypes) {
SCC = DAG.getSetCC(DL, CmpResVT, N0, N1, CC);
if (VT.bitsLT(SCC.getValueType()))
Temp = DAG.getZeroExtendInReg(SCC, SDLoc(N2), VT);
else
Temp = DAG.getNode(ISD::ZERO_EXTEND, SDLoc(N2), VT, SCC);
} else {
SCC = DAG.getSetCC(SDLoc(N0), MVT::i1, N0, N1, CC);
Temp = DAG.getNode(ISD::ZERO_EXTEND, SDLoc(N2), VT, SCC);
}
AddToWorklist(SCC.getNode());
AddToWorklist(Temp.getNode());
if (N2C->isOne())
return Temp;
unsigned ShCt = N2C->getAPIntValue().logBase2();
if (TLI.shouldAvoidTransformToShift(VT, ShCt))
return SDValue();
// shl setcc result by log2 n2c
return DAG.getNode(ISD::SHL, DL, N2.getValueType(), Temp,
DAG.getConstant(ShCt, SDLoc(Temp),
getShiftAmountTy(Temp.getValueType())));
}
// select_cc seteq X, 0, sizeof(X), ctlz(X) -> ctlz(X)
// select_cc seteq X, 0, sizeof(X), ctlz_zero_undef(X) -> ctlz(X)
// select_cc seteq X, 0, sizeof(X), cttz(X) -> cttz(X)
// select_cc seteq X, 0, sizeof(X), cttz_zero_undef(X) -> cttz(X)
// select_cc setne X, 0, ctlz(X), sizeof(X) -> ctlz(X)
// select_cc setne X, 0, ctlz_zero_undef(X), sizeof(X) -> ctlz(X)
// select_cc setne X, 0, cttz(X), sizeof(X) -> cttz(X)
// select_cc setne X, 0, cttz_zero_undef(X), sizeof(X) -> cttz(X)
if (N1C && N1C->isZero() && (CC == ISD::SETEQ || CC == ISD::SETNE)) {
SDValue ValueOnZero = N2;
SDValue Count = N3;
// If the condition is NE instead of E, swap the operands.
if (CC == ISD::SETNE)
std::swap(ValueOnZero, Count);
// Check if the value on zero is a constant equal to the bits in the type.
if (auto *ValueOnZeroC = dyn_cast<ConstantSDNode>(ValueOnZero)) {
if (ValueOnZeroC->getAPIntValue() == VT.getSizeInBits()) {
// If the other operand is cttz/cttz_zero_undef of N0, and cttz is
// legal, combine to just cttz.
if ((Count.getOpcode() == ISD::CTTZ ||
Count.getOpcode() == ISD::CTTZ_ZERO_UNDEF) &&
N0 == Count.getOperand(0) &&
(!LegalOperations || TLI.isOperationLegal(ISD::CTTZ, VT)))
return DAG.getNode(ISD::CTTZ, DL, VT, N0);
// If the other operand is ctlz/ctlz_zero_undef of N0, and ctlz is
// legal, combine to just ctlz.
if ((Count.getOpcode() == ISD::CTLZ ||
Count.getOpcode() == ISD::CTLZ_ZERO_UNDEF) &&
N0 == Count.getOperand(0) &&
(!LegalOperations || TLI.isOperationLegal(ISD::CTLZ, VT)))
return DAG.getNode(ISD::CTLZ, DL, VT, N0);
}
}
}
// Fold select_cc setgt X, -1, C, ~C -> xor (ashr X, BW-1), C
// Fold select_cc setlt X, 0, C, ~C -> xor (ashr X, BW-1), ~C
if (!NotExtCompare && N1C && N2C && N3C &&
N2C->getAPIntValue() == ~N3C->getAPIntValue() &&
((N1C->isAllOnes() && CC == ISD::SETGT) ||
(N1C->isZero() && CC == ISD::SETLT)) &&
!TLI.shouldAvoidTransformToShift(VT, CmpOpVT.getScalarSizeInBits() - 1)) {
SDValue ASR = DAG.getNode(
ISD::SRA, DL, CmpOpVT, N0,
DAG.getConstant(CmpOpVT.getScalarSizeInBits() - 1, DL, CmpOpVT));
return DAG.getNode(ISD::XOR, DL, VT, DAG.getSExtOrTrunc(ASR, DL, VT),
DAG.getSExtOrTrunc(CC == ISD::SETLT ? N3 : N2, DL, VT));
}
if (SDValue S = PerformMinMaxFpToSatCombine(N0, N1, N2, N3, CC, DAG))
return S;
if (SDValue S = PerformUMinFpToSatCombine(N0, N1, N2, N3, CC, DAG))
return S;
return SDValue();
}
/// This is a stub for TargetLowering::SimplifySetCC.
SDValue DAGCombiner::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
ISD::CondCode Cond, const SDLoc &DL,
bool foldBooleans) {
TargetLowering::DAGCombinerInfo
DagCombineInfo(DAG, Level, false, this);
return TLI.SimplifySetCC(VT, N0, N1, Cond, foldBooleans, DagCombineInfo, DL);
}
/// Given an ISD::SDIV node expressing a divide by constant, return
/// a DAG expression to select that will generate the same value by multiplying
/// by a magic number.
/// Ref: "Hacker's Delight" or "The PowerPC Compiler Writer's Guide".
SDValue DAGCombiner::BuildSDIV(SDNode *N) {
// when optimising for minimum size, we don't want to expand a div to a mul
// and a shift.
if (DAG.getMachineFunction().getFunction().hasMinSize())
return SDValue();
SmallVector<SDNode *, 8> Built;
if (SDValue S = TLI.BuildSDIV(N, DAG, LegalOperations, Built)) {
for (SDNode *N : Built)
AddToWorklist(N);
return S;
}
return SDValue();
}
/// Given an ISD::SDIV node expressing a divide by constant power of 2, return a
/// DAG expression that will generate the same value by right shifting.
SDValue DAGCombiner::BuildSDIVPow2(SDNode *N) {
ConstantSDNode *C = isConstOrConstSplat(N->getOperand(1));
if (!C)
return SDValue();
// Avoid division by zero.
if (C->isZero())
return SDValue();
SmallVector<SDNode *, 8> Built;
if (SDValue S = TLI.BuildSDIVPow2(N, C->getAPIntValue(), DAG, Built)) {
for (SDNode *N : Built)
AddToWorklist(N);
return S;
}
return SDValue();
}
/// Given an ISD::UDIV node expressing a divide by constant, return a DAG
/// expression that will generate the same value by multiplying by a magic
/// number.
/// Ref: "Hacker's Delight" or "The PowerPC Compiler Writer's Guide".
SDValue DAGCombiner::BuildUDIV(SDNode *N) {
// when optimising for minimum size, we don't want to expand a div to a mul
// and a shift.
if (DAG.getMachineFunction().getFunction().hasMinSize())
return SDValue();
SmallVector<SDNode *, 8> Built;
if (SDValue S = TLI.BuildUDIV(N, DAG, LegalOperations, Built)) {
for (SDNode *N : Built)
AddToWorklist(N);
return S;
}
return SDValue();
}
/// Given an ISD::SREM node expressing a remainder by constant power of 2,
/// return a DAG expression that will generate the same value.
SDValue DAGCombiner::BuildSREMPow2(SDNode *N) {
ConstantSDNode *C = isConstOrConstSplat(N->getOperand(1));
if (!C)
return SDValue();
// Avoid division by zero.
if (C->isZero())
return SDValue();
SmallVector<SDNode *, 8> Built;
if (SDValue S = TLI.BuildSREMPow2(N, C->getAPIntValue(), DAG, Built)) {
for (SDNode *N : Built)
AddToWorklist(N);
return S;
}
return SDValue();
}
/// Determines the LogBase2 value for a non-null input value using the
/// transform: LogBase2(V) = (EltBits - 1) - ctlz(V).
SDValue DAGCombiner::BuildLogBase2(SDValue V, const SDLoc &DL) {
EVT VT = V.getValueType();
SDValue Ctlz = DAG.getNode(ISD::CTLZ, DL, VT, V);
SDValue Base = DAG.getConstant(VT.getScalarSizeInBits() - 1, DL, VT);
SDValue LogBase2 = DAG.getNode(ISD::SUB, DL, VT, Base, Ctlz);
return LogBase2;
}
/// Newton iteration for a function: F(X) is X_{i+1} = X_i - F(X_i)/F'(X_i)
/// For the reciprocal, we need to find the zero of the function:
/// F(X) = 1/X - A [which has a zero at X = 1/A]
/// =>
/// X_{i+1} = X_i (2 - A X_i) = X_i + X_i (1 - A X_i) [this second form
/// does not require additional intermediate precision]
/// For the last iteration, put numerator N into it to gain more precision:
/// Result = N X_i + X_i (N - N A X_i)
SDValue DAGCombiner::BuildDivEstimate(SDValue N, SDValue Op,
SDNodeFlags Flags) {
if (LegalDAG)
return SDValue();
// TODO: Handle extended types?
EVT VT = Op.getValueType();
if (VT.getScalarType() != MVT::f16 && VT.getScalarType() != MVT::f32 &&
VT.getScalarType() != MVT::f64)
return SDValue();
// If estimates are explicitly disabled for this function, we're done.
MachineFunction &MF = DAG.getMachineFunction();
int Enabled = TLI.getRecipEstimateDivEnabled(VT, MF);
if (Enabled == TLI.ReciprocalEstimate::Disabled)
return SDValue();
// Estimates may be explicitly enabled for this type with a custom number of
// refinement steps.
int Iterations = TLI.getDivRefinementSteps(VT, MF);
if (SDValue Est = TLI.getRecipEstimate(Op, DAG, Enabled, Iterations)) {
AddToWorklist(Est.getNode());
SDLoc DL(Op);
if (Iterations) {
SDValue FPOne = DAG.getConstantFP(1.0, DL, VT);
// Newton iterations: Est = Est + Est (N - Arg * Est)
// If this is the last iteration, also multiply by the numerator.
for (int i = 0; i < Iterations; ++i) {
SDValue MulEst = Est;
if (i == Iterations - 1) {
MulEst = DAG.getNode(ISD::FMUL, DL, VT, N, Est, Flags);
AddToWorklist(MulEst.getNode());
}
SDValue NewEst = DAG.getNode(ISD::FMUL, DL, VT, Op, MulEst, Flags);
AddToWorklist(NewEst.getNode());
NewEst = DAG.getNode(ISD::FSUB, DL, VT,
(i == Iterations - 1 ? N : FPOne), NewEst, Flags);
AddToWorklist(NewEst.getNode());
NewEst = DAG.getNode(ISD::FMUL, DL, VT, Est, NewEst, Flags);
AddToWorklist(NewEst.getNode());
Est = DAG.getNode(ISD::FADD, DL, VT, MulEst, NewEst, Flags);
AddToWorklist(Est.getNode());
}
} else {
// If no iterations are available, multiply with N.
Est = DAG.getNode(ISD::FMUL, DL, VT, Est, N, Flags);
AddToWorklist(Est.getNode());
}
return Est;
}
return SDValue();
}
/// Newton iteration for a function: F(X) is X_{i+1} = X_i - F(X_i)/F'(X_i)
/// For the reciprocal sqrt, we need to find the zero of the function:
/// F(X) = 1/X^2 - A [which has a zero at X = 1/sqrt(A)]
/// =>
/// X_{i+1} = X_i (1.5 - A X_i^2 / 2)
/// As a result, we precompute A/2 prior to the iteration loop.
SDValue DAGCombiner::buildSqrtNROneConst(SDValue Arg, SDValue Est,
unsigned Iterations,
SDNodeFlags Flags, bool Reciprocal) {
EVT VT = Arg.getValueType();
SDLoc DL(Arg);
SDValue ThreeHalves = DAG.getConstantFP(1.5, DL, VT);
// We now need 0.5 * Arg which we can write as (1.5 * Arg - Arg) so that
// this entire sequence requires only one FP constant.
SDValue HalfArg = DAG.getNode(ISD::FMUL, DL, VT, ThreeHalves, Arg, Flags);
HalfArg = DAG.getNode(ISD::FSUB, DL, VT, HalfArg, Arg, Flags);
// Newton iterations: Est = Est * (1.5 - HalfArg * Est * Est)
for (unsigned i = 0; i < Iterations; ++i) {
SDValue NewEst = DAG.getNode(ISD::FMUL, DL, VT, Est, Est, Flags);
NewEst = DAG.getNode(ISD::FMUL, DL, VT, HalfArg, NewEst, Flags);
NewEst = DAG.getNode(ISD::FSUB, DL, VT, ThreeHalves, NewEst, Flags);
Est = DAG.getNode(ISD::FMUL, DL, VT, Est, NewEst, Flags);
}
// If non-reciprocal square root is requested, multiply the result by Arg.
if (!Reciprocal)
Est = DAG.getNode(ISD::FMUL, DL, VT, Est, Arg, Flags);
return Est;
}
/// Newton iteration for a function: F(X) is X_{i+1} = X_i - F(X_i)/F'(X_i)
/// For the reciprocal sqrt, we need to find the zero of the function:
/// F(X) = 1/X^2 - A [which has a zero at X = 1/sqrt(A)]
/// =>
/// X_{i+1} = (-0.5 * X_i) * (A * X_i * X_i + (-3.0))
SDValue DAGCombiner::buildSqrtNRTwoConst(SDValue Arg, SDValue Est,
unsigned Iterations,
SDNodeFlags Flags, bool Reciprocal) {
EVT VT = Arg.getValueType();
SDLoc DL(Arg);
SDValue MinusThree = DAG.getConstantFP(-3.0, DL, VT);
SDValue MinusHalf = DAG.getConstantFP(-0.5, DL, VT);
// This routine must enter the loop below to work correctly
// when (Reciprocal == false).
assert(Iterations > 0);
// Newton iterations for reciprocal square root:
// E = (E * -0.5) * ((A * E) * E + -3.0)
for (unsigned i = 0; i < Iterations; ++i) {
SDValue AE = DAG.getNode(ISD::FMUL, DL, VT, Arg, Est, Flags);
SDValue AEE = DAG.getNode(ISD::FMUL, DL, VT, AE, Est, Flags);
SDValue RHS = DAG.getNode(ISD::FADD, DL, VT, AEE, MinusThree, Flags);
// When calculating a square root at the last iteration build:
// S = ((A * E) * -0.5) * ((A * E) * E + -3.0)
// (notice a common subexpression)
SDValue LHS;
if (Reciprocal || (i + 1) < Iterations) {
// RSQRT: LHS = (E * -0.5)
LHS = DAG.getNode(ISD::FMUL, DL, VT, Est, MinusHalf, Flags);
} else {
// SQRT: LHS = (A * E) * -0.5
LHS = DAG.getNode(ISD::FMUL, DL, VT, AE, MinusHalf, Flags);
}
Est = DAG.getNode(ISD::FMUL, DL, VT, LHS, RHS, Flags);
}
return Est;
}
/// Build code to calculate either rsqrt(Op) or sqrt(Op). In the latter case
/// Op*rsqrt(Op) is actually computed, so additional postprocessing is needed if
/// Op can be zero.
SDValue DAGCombiner::buildSqrtEstimateImpl(SDValue Op, SDNodeFlags Flags,
bool Reciprocal) {
if (LegalDAG)
return SDValue();
// TODO: Handle extended types?
EVT VT = Op.getValueType();
if (VT.getScalarType() != MVT::f16 && VT.getScalarType() != MVT::f32 &&
VT.getScalarType() != MVT::f64)
return SDValue();
// If estimates are explicitly disabled for this function, we're done.
MachineFunction &MF = DAG.getMachineFunction();
int Enabled = TLI.getRecipEstimateSqrtEnabled(VT, MF);
if (Enabled == TLI.ReciprocalEstimate::Disabled)
return SDValue();
// Estimates may be explicitly enabled for this type with a custom number of
// refinement steps.
int Iterations = TLI.getSqrtRefinementSteps(VT, MF);
bool UseOneConstNR = false;
if (SDValue Est =
TLI.getSqrtEstimate(Op, DAG, Enabled, Iterations, UseOneConstNR,
Reciprocal)) {
AddToWorklist(Est.getNode());
if (Iterations)
Est = UseOneConstNR
? buildSqrtNROneConst(Op, Est, Iterations, Flags, Reciprocal)
: buildSqrtNRTwoConst(Op, Est, Iterations, Flags, Reciprocal);
if (!Reciprocal) {
SDLoc DL(Op);
// Try the target specific test first.
SDValue Test = TLI.getSqrtInputTest(Op, DAG, DAG.getDenormalMode(VT));
// The estimate is now completely wrong if the input was exactly 0.0 or
// possibly a denormal. Force the answer to 0.0 or value provided by
// target for those cases.
Est = DAG.getNode(
Test.getValueType().isVector() ? ISD::VSELECT : ISD::SELECT, DL, VT,
Test, TLI.getSqrtResultForDenormInput(Op, DAG), Est);
}
return Est;
}
return SDValue();
}
SDValue DAGCombiner::buildRsqrtEstimate(SDValue Op, SDNodeFlags Flags) {
return buildSqrtEstimateImpl(Op, Flags, true);
}
SDValue DAGCombiner::buildSqrtEstimate(SDValue Op, SDNodeFlags Flags) {
return buildSqrtEstimateImpl(Op, Flags, false);
}
/// Return true if there is any possibility that the two addresses overlap.
bool DAGCombiner::mayAlias(SDNode *Op0, SDNode *Op1) const {
struct MemUseCharacteristics {
bool IsVolatile;
bool IsAtomic;
SDValue BasePtr;
int64_t Offset;
Optional<int64_t> NumBytes;
MachineMemOperand *MMO;
};
auto getCharacteristics = [](SDNode *N) -> MemUseCharacteristics {
if (const auto *LSN = dyn_cast<LSBaseSDNode>(N)) {
int64_t Offset = 0;
if (auto *C = dyn_cast<ConstantSDNode>(LSN->getOffset()))
Offset = (LSN->getAddressingMode() == ISD::PRE_INC)
? C->getSExtValue()
: (LSN->getAddressingMode() == ISD::PRE_DEC)
? -1 * C->getSExtValue()
: 0;
uint64_t Size =
MemoryLocation::getSizeOrUnknown(LSN->getMemoryVT().getStoreSize());
return {LSN->isVolatile(), LSN->isAtomic(), LSN->getBasePtr(),
Offset /*base offset*/,
Optional<int64_t>(Size),
LSN->getMemOperand()};
}
if (const auto *LN = cast<LifetimeSDNode>(N))
return {false /*isVolatile*/, /*isAtomic*/ false, LN->getOperand(1),
(LN->hasOffset()) ? LN->getOffset() : 0,
(LN->hasOffset()) ? Optional<int64_t>(LN->getSize())
: Optional<int64_t>(),
(MachineMemOperand *)nullptr};
// Default.
return {false /*isvolatile*/, /*isAtomic*/ false, SDValue(),
(int64_t)0 /*offset*/,
Optional<int64_t>() /*size*/, (MachineMemOperand *)nullptr};
};
MemUseCharacteristics MUC0 = getCharacteristics(Op0),
MUC1 = getCharacteristics(Op1);
// If they are to the same address, then they must be aliases.
if (MUC0.BasePtr.getNode() && MUC0.BasePtr == MUC1.BasePtr &&
MUC0.Offset == MUC1.Offset)
return true;
// If they are both volatile then they cannot be reordered.
if (MUC0.IsVolatile && MUC1.IsVolatile)
return true;
// Be conservative about atomics for the moment
// TODO: This is way overconservative for unordered atomics (see D66309)
if (MUC0.IsAtomic && MUC1.IsAtomic)
return true;
if (MUC0.MMO && MUC1.MMO) {
if ((MUC0.MMO->isInvariant() && MUC1.MMO->isStore()) ||
(MUC1.MMO->isInvariant() && MUC0.MMO->isStore()))
return false;
}
// Try to prove that there is aliasing, or that there is no aliasing. Either
// way, we can return now. If nothing can be proved, proceed with more tests.
bool IsAlias;
if (BaseIndexOffset::computeAliasing(Op0, MUC0.NumBytes, Op1, MUC1.NumBytes,
DAG, IsAlias))
return IsAlias;
// The following all rely on MMO0 and MMO1 being valid. Fail conservatively if
// either are not known.
if (!MUC0.MMO || !MUC1.MMO)
return true;
// If one operation reads from invariant memory, and the other may store, they
// cannot alias. These should really be checking the equivalent of mayWrite,
// but it only matters for memory nodes other than load /store.
if ((MUC0.MMO->isInvariant() && MUC1.MMO->isStore()) ||
(MUC1.MMO->isInvariant() && MUC0.MMO->isStore()))
return false;
// If we know required SrcValue1 and SrcValue2 have relatively large
// alignment compared to the size and offset of the access, we may be able
// to prove they do not alias. This check is conservative for now to catch
// cases created by splitting vector types, it only works when the offsets are
// multiples of the size of the data.
int64_t SrcValOffset0 = MUC0.MMO->getOffset();
int64_t SrcValOffset1 = MUC1.MMO->getOffset();
Align OrigAlignment0 = MUC0.MMO->getBaseAlign();
Align OrigAlignment1 = MUC1.MMO->getBaseAlign();
auto &Size0 = MUC0.NumBytes;
auto &Size1 = MUC1.NumBytes;
if (OrigAlignment0 == OrigAlignment1 && SrcValOffset0 != SrcValOffset1 &&
Size0.hasValue() && Size1.hasValue() && *Size0 == *Size1 &&
OrigAlignment0 > *Size0 && SrcValOffset0 % *Size0 == 0 &&
SrcValOffset1 % *Size1 == 0) {
int64_t OffAlign0 = SrcValOffset0 % OrigAlignment0.value();
int64_t OffAlign1 = SrcValOffset1 % OrigAlignment1.value();
// There is no overlap between these relatively aligned accesses of
// similar size. Return no alias.
if ((OffAlign0 + *Size0) <= OffAlign1 || (OffAlign1 + *Size1) <= OffAlign0)
return false;
}
bool UseAA = CombinerGlobalAA.getNumOccurrences() > 0
? CombinerGlobalAA
: DAG.getSubtarget().useAA();
#ifndef NDEBUG
if (CombinerAAOnlyFunc.getNumOccurrences() &&
CombinerAAOnlyFunc != DAG.getMachineFunction().getName())
UseAA = false;
#endif
if (UseAA && AA && MUC0.MMO->getValue() && MUC1.MMO->getValue() &&
Size0.hasValue() && Size1.hasValue()) {
// Use alias analysis information.
int64_t MinOffset = std::min(SrcValOffset0, SrcValOffset1);
int64_t Overlap0 = *Size0 + SrcValOffset0 - MinOffset;
int64_t Overlap1 = *Size1 + SrcValOffset1 - MinOffset;
if (AA->isNoAlias(
MemoryLocation(MUC0.MMO->getValue(), Overlap0,
UseTBAA ? MUC0.MMO->getAAInfo() : AAMDNodes()),
MemoryLocation(MUC1.MMO->getValue(), Overlap1,
UseTBAA ? MUC1.MMO->getAAInfo() : AAMDNodes())))
return false;
}
// Otherwise we have to assume they alias.
return true;
}
/// Walk up chain skipping non-aliasing memory nodes,
/// looking for aliasing nodes and adding them to the Aliases vector.
void DAGCombiner::GatherAllAliases(SDNode *N, SDValue OriginalChain,
SmallVectorImpl<SDValue> &Aliases) {
SmallVector<SDValue, 8> Chains; // List of chains to visit.
SmallPtrSet<SDNode *, 16> Visited; // Visited node set.
// Get alias information for node.
// TODO: relax aliasing for unordered atomics (see D66309)
const bool IsLoad = isa<LoadSDNode>(N) && cast<LoadSDNode>(N)->isSimple();
// Starting off.
Chains.push_back(OriginalChain);
unsigned Depth = 0;
// Attempt to improve chain by a single step
auto ImproveChain = [&](SDValue &C) -> bool {
switch (C.getOpcode()) {
case ISD::EntryToken:
// No need to mark EntryToken.
C = SDValue();
return true;
case ISD::LOAD:
case ISD::STORE: {
// Get alias information for C.
// TODO: Relax aliasing for unordered atomics (see D66309)
bool IsOpLoad = isa<LoadSDNode>(C.getNode()) &&
cast<LSBaseSDNode>(C.getNode())->isSimple();
if ((IsLoad && IsOpLoad) || !mayAlias(N, C.getNode())) {
// Look further up the chain.
C = C.getOperand(0);
return true;
}
// Alias, so stop here.
return false;
}
case ISD::CopyFromReg:
// Always forward past past CopyFromReg.
C = C.getOperand(0);
return true;
case ISD::LIFETIME_START:
case ISD::LIFETIME_END: {
// We can forward past any lifetime start/end that can be proven not to
// alias the memory access.
if (!mayAlias(N, C.getNode())) {
// Look further up the chain.
C = C.getOperand(0);
return true;
}
return false;
}
default:
return false;
}
};
// Look at each chain and determine if it is an alias. If so, add it to the
// aliases list. If not, then continue up the chain looking for the next
// candidate.
while (!Chains.empty()) {
SDValue Chain = Chains.pop_back_val();
// Don't bother if we've seen Chain before.
if (!Visited.insert(Chain.getNode()).second)
continue;
// For TokenFactor nodes, look at each operand and only continue up the
// chain until we reach the depth limit.
//
// FIXME: The depth check could be made to return the last non-aliasing
// chain we found before we hit a tokenfactor rather than the original
// chain.
if (Depth > TLI.getGatherAllAliasesMaxDepth()) {
Aliases.clear();
Aliases.push_back(OriginalChain);
return;
}
if (Chain.getOpcode() == ISD::TokenFactor) {
// We have to check each of the operands of the token factor for "small"
// token factors, so we queue them up. Adding the operands to the queue
// (stack) in reverse order maintains the original order and increases the
// likelihood that getNode will find a matching token factor (CSE.)
if (Chain.getNumOperands() > 16) {
Aliases.push_back(Chain);
continue;
}
for (unsigned n = Chain.getNumOperands(); n;)
Chains.push_back(Chain.getOperand(--n));
++Depth;
continue;
}
// Everything else
if (ImproveChain(Chain)) {
// Updated Chain Found, Consider new chain if one exists.
if (Chain.getNode())
Chains.push_back(Chain);
++Depth;
continue;
}
// No Improved Chain Possible, treat as Alias.
Aliases.push_back(Chain);
}
}
/// Walk up chain skipping non-aliasing memory nodes, looking for a better chain
/// (aliasing node.)
SDValue DAGCombiner::FindBetterChain(SDNode *N, SDValue OldChain) {
if (OptLevel == CodeGenOpt::None)
return OldChain;
// Ops for replacing token factor.
SmallVector<SDValue, 8> Aliases;
// Accumulate all the aliases to this node.
GatherAllAliases(N, OldChain, Aliases);
// If no operands then chain to entry token.
if (Aliases.size() == 0)
return DAG.getEntryNode();
// If a single operand then chain to it. We don't need to revisit it.
if (Aliases.size() == 1)
return Aliases[0];
// Construct a custom tailored token factor.
return DAG.getTokenFactor(SDLoc(N), Aliases);
}
namespace {
// TODO: Replace with with std::monostate when we move to C++17.
struct UnitT { } Unit;
bool operator==(const UnitT &, const UnitT &) { return true; }
bool operator!=(const UnitT &, const UnitT &) { return false; }
} // namespace
// This function tries to collect a bunch of potentially interesting
// nodes to improve the chains of, all at once. This might seem
// redundant, as this function gets called when visiting every store
// node, so why not let the work be done on each store as it's visited?
//
// I believe this is mainly important because mergeConsecutiveStores
// is unable to deal with merging stores of different sizes, so unless
// we improve the chains of all the potential candidates up-front
// before running mergeConsecutiveStores, it might only see some of
// the nodes that will eventually be candidates, and then not be able
// to go from a partially-merged state to the desired final
// fully-merged state.
bool DAGCombiner::parallelizeChainedStores(StoreSDNode *St) {
SmallVector<StoreSDNode *, 8> ChainedStores;
StoreSDNode *STChain = St;
// Intervals records which offsets from BaseIndex have been covered. In
// the common case, every store writes to the immediately previous address
// space and thus merged with the previous interval at insertion time.
using IMap =
llvm::IntervalMap<int64_t, UnitT, 8, IntervalMapHalfOpenInfo<int64_t>>;
IMap::Allocator A;
IMap Intervals(A);
// This holds the base pointer, index, and the offset in bytes from the base
// pointer.
const BaseIndexOffset BasePtr = BaseIndexOffset::match(St, DAG);
// We must have a base and an offset.
if (!BasePtr.getBase().getNode())
return false;
// Do not handle stores to undef base pointers.
if (BasePtr.getBase().isUndef())
return false;
// Do not handle stores to opaque types
if (St->getMemoryVT().isZeroSized())
return false;
// BaseIndexOffset assumes that offsets are fixed-size, which
// is not valid for scalable vectors where the offsets are
// scaled by `vscale`, so bail out early.
if (St->getMemoryVT().isScalableVector())
return false;
// Add ST's interval.
Intervals.insert(0, (St->getMemoryVT().getSizeInBits() + 7) / 8, Unit);
while (StoreSDNode *Chain = dyn_cast<StoreSDNode>(STChain->getChain())) {
if (Chain->getMemoryVT().isScalableVector())
return false;
// If the chain has more than one use, then we can't reorder the mem ops.
if (!SDValue(Chain, 0)->hasOneUse())
break;
// TODO: Relax for unordered atomics (see D66309)
if (!Chain->isSimple() || Chain->isIndexed())
break;
// Find the base pointer and offset for this memory node.
const BaseIndexOffset Ptr = BaseIndexOffset::match(Chain, DAG);
// Check that the base pointer is the same as the original one.
int64_t Offset;
if (!BasePtr.equalBaseIndex(Ptr, DAG, Offset))
break;
int64_t Length = (Chain->getMemoryVT().getSizeInBits() + 7) / 8;
// Make sure we don't overlap with other intervals by checking the ones to
// the left or right before inserting.
auto I = Intervals.find(Offset);
// If there's a next interval, we should end before it.
if (I != Intervals.end() && I.start() < (Offset + Length))
break;
// If there's a previous interval, we should start after it.
if (I != Intervals.begin() && (--I).stop() <= Offset)
break;
Intervals.insert(Offset, Offset + Length, Unit);
ChainedStores.push_back(Chain);
STChain = Chain;
}
// If we didn't find a chained store, exit.
if (ChainedStores.size() == 0)
return false;
// Improve all chained stores (St and ChainedStores members) starting from
// where the store chain ended and return single TokenFactor.
SDValue NewChain = STChain->getChain();
SmallVector<SDValue, 8> TFOps;
for (unsigned I = ChainedStores.size(); I;) {
StoreSDNode *S = ChainedStores[--I];
SDValue BetterChain = FindBetterChain(S, NewChain);
S = cast<StoreSDNode>(DAG.UpdateNodeOperands(
S, BetterChain, S->getOperand(1), S->getOperand(2), S->getOperand(3)));
TFOps.push_back(SDValue(S, 0));
ChainedStores[I] = S;
}
// Improve St's chain. Use a new node to avoid creating a loop from CombineTo.
SDValue BetterChain = FindBetterChain(St, NewChain);
SDValue NewST;
if (St->isTruncatingStore())
NewST = DAG.getTruncStore(BetterChain, SDLoc(St), St->getValue(),
St->getBasePtr(), St->getMemoryVT(),
St->getMemOperand());
else
NewST = DAG.getStore(BetterChain, SDLoc(St), St->getValue(),
St->getBasePtr(), St->getMemOperand());
TFOps.push_back(NewST);
// If we improved every element of TFOps, then we've lost the dependence on
// NewChain to successors of St and we need to add it back to TFOps. Do so at
// the beginning to keep relative order consistent with FindBetterChains.
auto hasImprovedChain = [&](SDValue ST) -> bool {
return ST->getOperand(0) != NewChain;
};
bool AddNewChain = llvm::all_of(TFOps, hasImprovedChain);
if (AddNewChain)
TFOps.insert(TFOps.begin(), NewChain);
SDValue TF = DAG.getTokenFactor(SDLoc(STChain), TFOps);
CombineTo(St, TF);
// Add TF and its operands to the worklist.
AddToWorklist(TF.getNode());
for (const SDValue &Op : TF->ops())
AddToWorklist(Op.getNode());
AddToWorklist(STChain);
return true;
}
bool DAGCombiner::findBetterNeighborChains(StoreSDNode *St) {
if (OptLevel == CodeGenOpt::None)
return false;
const BaseIndexOffset BasePtr = BaseIndexOffset::match(St, DAG);
// We must have a base and an offset.
if (!BasePtr.getBase().getNode())
return false;
// Do not handle stores to undef base pointers.
if (BasePtr.getBase().isUndef())
return false;
// Directly improve a chain of disjoint stores starting at St.
if (parallelizeChainedStores(St))
return true;
// Improve St's Chain..
SDValue BetterChain = FindBetterChain(St, St->getChain());
if (St->getChain() != BetterChain) {
replaceStoreChain(St, BetterChain);
return true;
}
return false;
}
/// This is the entry point for the file.
void SelectionDAG::Combine(CombineLevel Level, AliasAnalysis *AA,
CodeGenOpt::Level OptLevel) {
/// This is the main entry point to this class.
DAGCombiner(*this, AA, OptLevel).Run(Level);
}
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