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llvm-project/polly/lib/CodeGen/BlockGenerators.cpp

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//===--- BlockGenerators.cpp - Generate code for statements -----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the BlockGenerator and VectorBlockGenerator classes,
// which generate sequential code and vectorized code for a polyhedral
// statement, respectively.
//
//===----------------------------------------------------------------------===//
#include "polly/ScopInfo.h"
#include "polly/CodeGen/BlockGenerators.h"
#include "polly/CodeGen/CodeGeneration.h"
#include "polly/CodeGen/IslExprBuilder.h"
#include "polly/CodeGen/RuntimeDebugBuilder.h"
#include "polly/Options.h"
#include "polly/Support/GICHelper.h"
#include "polly/Support/SCEVValidator.h"
#include "polly/Support/ScopHelper.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/RegionInfo.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "isl/aff.h"
#include "isl/ast.h"
#include "isl/ast_build.h"
#include "isl/set.h"
#include <deque>
using namespace llvm;
using namespace polly;
static cl::opt<bool> Aligned("enable-polly-aligned",
cl::desc("Assumed aligned memory accesses."),
cl::Hidden, cl::init(false), cl::ZeroOrMore,
cl::cat(PollyCategory));
static cl::opt<bool> DebugPrinting(
"polly-codegen-add-debug-printing",
cl::desc("Add printf calls that show the values loaded/stored."),
cl::Hidden, cl::init(false), cl::ZeroOrMore, cl::cat(PollyCategory));
bool polly::canSynthesize(const Value *V, const llvm::LoopInfo *LI,
ScalarEvolution *SE, const Region *R) {
if (!V || !SE->isSCEVable(V->getType()))
return false;
if (const SCEV *Scev = SE->getSCEV(const_cast<Value *>(V)))
if (!isa<SCEVCouldNotCompute>(Scev))
if (!hasScalarDepsInsideRegion(Scev, R))
return true;
return false;
}
bool polly::isIgnoredIntrinsic(const Value *V) {
if (auto *IT = dyn_cast<IntrinsicInst>(V)) {
switch (IT->getIntrinsicID()) {
// Lifetime markers are supported/ignored.
case llvm::Intrinsic::lifetime_start:
case llvm::Intrinsic::lifetime_end:
// Invariant markers are supported/ignored.
case llvm::Intrinsic::invariant_start:
case llvm::Intrinsic::invariant_end:
// Some misc annotations are supported/ignored.
case llvm::Intrinsic::var_annotation:
case llvm::Intrinsic::ptr_annotation:
case llvm::Intrinsic::annotation:
case llvm::Intrinsic::donothing:
case llvm::Intrinsic::assume:
case llvm::Intrinsic::expect:
// Some debug info intrisics are supported/ignored.
case llvm::Intrinsic::dbg_value:
case llvm::Intrinsic::dbg_declare:
return true;
default:
break;
}
}
return false;
}
BlockGenerator::BlockGenerator(PollyIRBuilder &B, LoopInfo &LI,
ScalarEvolution &SE, DominatorTree &DT,
ScalarAllocaMapTy &ScalarMap,
ScalarAllocaMapTy &PHIOpMap,
EscapeUsersAllocaMapTy &EscapeMap,
ValueToValueMap &GlobalMap,
IslExprBuilder *ExprBuilder)
: Builder(B), LI(LI), SE(SE), ExprBuilder(ExprBuilder), DT(DT),
EntryBB(nullptr), PHIOpMap(PHIOpMap), ScalarMap(ScalarMap),
EscapeMap(EscapeMap), GlobalMap(GlobalMap) {}
Value *BlockGenerator::getNewValue(ScopStmt &Stmt, const Value *Old,
ValueMapT &BBMap, LoopToScevMapT &LTS,
Loop *L) const {
// We assume constants never change.
// This avoids map lookups for many calls to this function.
if (isa<Constant>(Old))
return const_cast<Value *>(Old);
if (Value *New = GlobalMap.lookup(Old)) {
if (Old->getType()->getScalarSizeInBits() <
New->getType()->getScalarSizeInBits())
New = Builder.CreateTruncOrBitCast(New, Old->getType());
return New;
}
if (Value *New = BBMap.lookup(Old))
return New;
if (SE.isSCEVable(Old->getType()))
if (const SCEV *Scev = SE.getSCEVAtScope(const_cast<Value *>(Old), L)) {
if (!isa<SCEVCouldNotCompute>(Scev)) {
const SCEV *NewScev = apply(Scev, LTS, SE);
ValueToValueMap VTV;
VTV.insert(BBMap.begin(), BBMap.end());
VTV.insert(GlobalMap.begin(), GlobalMap.end());
NewScev = SCEVParameterRewriter::rewrite(NewScev, SE, VTV);
Scop &S = *Stmt.getParent();
const DataLayout &DL =
S.getRegion().getEntry()->getParent()->getParent()->getDataLayout();
auto IP = Builder.GetInsertPoint();
assert(IP != Builder.GetInsertBlock()->end() &&
"Only instructions can be insert points for SCEVExpander");
Value *Expanded =
expandCodeFor(S, SE, DL, "polly", NewScev, Old->getType(), IP);
BBMap[Old] = Expanded;
return Expanded;
}
}
// A scop-constant value defined by a global or a function parameter.
if (isa<GlobalValue>(Old) || isa<Argument>(Old))
return const_cast<Value *>(Old);
// A scop-constant value defined by an instruction executed outside the scop.
if (const Instruction *Inst = dyn_cast<Instruction>(Old))
if (!Stmt.getParent()->getRegion().contains(Inst->getParent()))
return const_cast<Value *>(Old);
// The scalar dependence is neither available nor SCEVCodegenable.
llvm_unreachable("Unexpected scalar dependence in region!");
return nullptr;
}
void BlockGenerator::copyInstScalar(ScopStmt &Stmt, const Instruction *Inst,
ValueMapT &BBMap, LoopToScevMapT &LTS) {
// We do not generate debug intrinsics as we did not investigate how to
// copy them correctly. At the current state, they just crash the code
// generation as the meta-data operands are not correctly copied.
if (isa<DbgInfoIntrinsic>(Inst))
return;
Instruction *NewInst = Inst->clone();
// Replace old operands with the new ones.
for (Value *OldOperand : Inst->operands()) {
Value *NewOperand =
getNewValue(Stmt, OldOperand, BBMap, LTS, getLoopForInst(Inst));
if (!NewOperand) {
assert(!isa<StoreInst>(NewInst) &&
"Store instructions are always needed!");
delete NewInst;
return;
}
NewInst->replaceUsesOfWith(OldOperand, NewOperand);
}
Builder.Insert(NewInst);
BBMap[Inst] = NewInst;
if (!NewInst->getType()->isVoidTy())
NewInst->setName("p_" + Inst->getName());
}
Value *BlockGenerator::generateLocationAccessed(
ScopStmt &Stmt, const Instruction *Inst, const Value *Pointer,
ValueMapT &BBMap, LoopToScevMapT &LTS, isl_id_to_ast_expr *NewAccesses) {
const MemoryAccess &MA = Stmt.getAccessFor(Inst);
isl_ast_expr *AccessExpr = isl_id_to_ast_expr_get(NewAccesses, MA.getId());
if (AccessExpr) {
AccessExpr = isl_ast_expr_address_of(AccessExpr);
auto Address = ExprBuilder->create(AccessExpr);
// Cast the address of this memory access to a pointer type that has the
// same element type as the original access, but uses the address space of
// the newly generated pointer.
auto OldPtrTy = MA.getAccessValue()->getType()->getPointerTo();
auto NewPtrTy = Address->getType();
OldPtrTy = PointerType::get(OldPtrTy->getElementType(),
NewPtrTy->getPointerAddressSpace());
if (OldPtrTy != NewPtrTy) {
assert(OldPtrTy->getPointerElementType()->getPrimitiveSizeInBits() ==
NewPtrTy->getPointerElementType()->getPrimitiveSizeInBits() &&
"Pointer types to elements with different size found");
Address = Builder.CreateBitOrPointerCast(Address, OldPtrTy);
}
return Address;
}
return getNewValue(Stmt, Pointer, BBMap, LTS, getLoopForInst(Inst));
}
Loop *BlockGenerator::getLoopForInst(const llvm::Instruction *Inst) {
return LI.getLoopFor(Inst->getParent());
}
Value *BlockGenerator::generateScalarLoad(ScopStmt &Stmt, const LoadInst *Load,
ValueMapT &BBMap, LoopToScevMapT &LTS,
isl_id_to_ast_expr *NewAccesses) {
const Value *Pointer = Load->getPointerOperand();
Value *NewPointer =
generateLocationAccessed(Stmt, Load, Pointer, BBMap, LTS, NewAccesses);
Value *ScalarLoad = Builder.CreateAlignedLoad(
NewPointer, Load->getAlignment(), Load->getName() + "_p_scalar_");
if (DebugPrinting)
RuntimeDebugBuilder::createCPUPrinter(Builder, "Load from ", NewPointer,
": ", ScalarLoad, "\n");
return ScalarLoad;
}
void BlockGenerator::generateScalarStore(ScopStmt &Stmt, const StoreInst *Store,
ValueMapT &BBMap, LoopToScevMapT &LTS,
isl_id_to_ast_expr *NewAccesses) {
const Value *Pointer = Store->getPointerOperand();
Value *NewPointer =
generateLocationAccessed(Stmt, Store, Pointer, BBMap, LTS, NewAccesses);
Value *ValueOperand = getNewValue(Stmt, Store->getValueOperand(), BBMap, LTS,
getLoopForInst(Store));
if (DebugPrinting)
RuntimeDebugBuilder::createCPUPrinter(Builder, "Store to ", NewPointer,
": ", ValueOperand, "\n");
Builder.CreateAlignedStore(ValueOperand, NewPointer, Store->getAlignment());
}
void BlockGenerator::copyInstruction(ScopStmt &Stmt, const Instruction *Inst,
ValueMapT &BBMap, LoopToScevMapT &LTS,
isl_id_to_ast_expr *NewAccesses) {
// First check for possible scalar dependences for this instruction.
generateScalarLoads(Stmt, Inst, BBMap);
// Terminator instructions control the control flow. They are explicitly
// expressed in the clast and do not need to be copied.
if (Inst->isTerminator())
return;
Loop *L = getLoopForInst(Inst);
if ((Stmt.isBlockStmt() || !Stmt.getRegion()->contains(L)) &&
canSynthesize(Inst, &LI, &SE, &Stmt.getParent()->getRegion())) {
// Synthesizable statements will be generated on-demand.
return;
}
if (const LoadInst *Load = dyn_cast<LoadInst>(Inst)) {
Value *NewLoad = generateScalarLoad(Stmt, Load, BBMap, LTS, NewAccesses);
// Compute NewLoad before its insertion in BBMap to make the insertion
// deterministic.
BBMap[Load] = NewLoad;
return;
}
if (const StoreInst *Store = dyn_cast<StoreInst>(Inst)) {
generateScalarStore(Stmt, Store, BBMap, LTS, NewAccesses);
return;
}
if (const PHINode *PHI = dyn_cast<PHINode>(Inst)) {
copyPHIInstruction(Stmt, PHI, BBMap, LTS);
return;
}
// Skip some special intrinsics for which we do not adjust the semantics to
// the new schedule. All others are handled like every other instruction.
if (isIgnoredIntrinsic(Inst))
return;
copyInstScalar(Stmt, Inst, BBMap, LTS);
}
void BlockGenerator::copyStmt(ScopStmt &Stmt, LoopToScevMapT &LTS,
isl_id_to_ast_expr *NewAccesses) {
assert(Stmt.isBlockStmt() &&
"Only block statements can be copied by the block generator");
ValueMapT BBMap;
BasicBlock *BB = Stmt.getBasicBlock();
copyBB(Stmt, BB, BBMap, LTS, NewAccesses);
}
BasicBlock *BlockGenerator::splitBB(BasicBlock *BB) {
BasicBlock *CopyBB =
SplitBlock(Builder.GetInsertBlock(), Builder.GetInsertPoint(), &DT, &LI);
CopyBB->setName("polly.stmt." + BB->getName());
return CopyBB;
}
BasicBlock *BlockGenerator::copyBB(ScopStmt &Stmt, BasicBlock *BB,
ValueMapT &BBMap, LoopToScevMapT &LTS,
isl_id_to_ast_expr *NewAccesses) {
BasicBlock *CopyBB = splitBB(BB);
copyBB(Stmt, BB, CopyBB, BBMap, LTS, NewAccesses);
return CopyBB;
}
void BlockGenerator::copyBB(ScopStmt &Stmt, BasicBlock *BB, BasicBlock *CopyBB,
ValueMapT &BBMap, LoopToScevMapT &LTS,
isl_id_to_ast_expr *NewAccesses) {
Builder.SetInsertPoint(CopyBB->begin());
EntryBB = &CopyBB->getParent()->getEntryBlock();
for (Instruction &Inst : *BB)
copyInstruction(Stmt, &Inst, BBMap, LTS, NewAccesses);
// After a basic block was copied store all scalars that escape this block
// in their alloca. First the scalars that have dependences inside the SCoP,
// then the ones that might escape the SCoP.
generateScalarStores(Stmt, BB, BBMap);
const Region &R = Stmt.getParent()->getRegion();
for (Instruction &Inst : *BB)
handleOutsideUsers(R, &Inst, BBMap[&Inst]);
}
Value *BlockGenerator::getOrCreateAlloca(Value *ScalarBase,
ScalarAllocaMapTy &Map,
const char *NameExt) {
// Check if an alloca was cached for the base instruction.
Value *&Addr = Map[ScalarBase];
// If no alloca was found create one and insert it in the entry block.
if (!Addr) {
auto *Ty = ScalarBase->getType();
auto NewAddr = new AllocaInst(Ty, ScalarBase->getName() + NameExt);
EntryBB = &Builder.GetInsertBlock()->getParent()->getEntryBlock();
NewAddr->insertBefore(EntryBB->getFirstInsertionPt());
Addr = NewAddr;
}
if (GlobalMap.count(Addr))
return GlobalMap[Addr];
return Addr;
}
Value *BlockGenerator::getOrCreateAlloca(MemoryAccess &Access) {
if (Access.getScopArrayInfo()->isPHI())
return getOrCreatePHIAlloca(Access.getBaseAddr());
else
return getOrCreateScalarAlloca(Access.getBaseAddr());
}
Value *BlockGenerator::getOrCreateScalarAlloca(Value *ScalarBase) {
return getOrCreateAlloca(ScalarBase, ScalarMap, ".s2a");
}
Value *BlockGenerator::getOrCreatePHIAlloca(Value *ScalarBase) {
return getOrCreateAlloca(ScalarBase, PHIOpMap, ".phiops");
}
void BlockGenerator::handleOutsideUsers(const Region &R, Instruction *Inst,
Value *InstCopy, Value *Address) {
// If there are escape users we get the alloca for this instruction and put it
// in the EscapeMap for later finalization. Lastly, if the instruction was
// copied multiple times we already did this and can exit.
if (EscapeMap.count(Inst))
return;
EscapeUserVectorTy EscapeUsers;
for (User *U : Inst->users()) {
// Non-instruction user will never escape.
Instruction *UI = dyn_cast<Instruction>(U);
if (!UI)
continue;
if (R.contains(UI))
continue;
EscapeUsers.push_back(UI);
}
// Exit if no escape uses were found.
if (EscapeUsers.empty())
return;
// Get or create an escape alloca for this instruction.
auto *ScalarAddr = Address ? Address : getOrCreateScalarAlloca(Inst);
// Remember that this instruction has escape uses and the escape alloca.
EscapeMap[Inst] = std::make_pair(ScalarAddr, std::move(EscapeUsers));
}
void BlockGenerator::generateScalarLoads(ScopStmt &Stmt,
const Instruction *Inst,
ValueMapT &BBMap) {
auto *MAL = Stmt.lookupAccessesFor(Inst);
if (!MAL)
return;
for (MemoryAccess *MA : *MAL) {
if (MA->isExplicit() || !MA->isRead())
continue;
auto *Address = getOrCreateAlloca(*MA);
BBMap[MA->getBaseAddr()] =
Builder.CreateLoad(Address, Address->getName() + ".reload");
}
}
Value *BlockGenerator::getNewScalarValue(Value *ScalarValue, const Region &R,
ValueMapT &BBMap) {
// If the value we want to store is an instruction we might have demoted it
// in order to make it accessible here. In such a case a reload is
// necessary. If it is no instruction it will always be a value that
// dominates the current point and we can just use it. In total there are 4
// options:
// (1) The value is no instruction ==> use the value.
// (2) The value is an instruction that was split out of the region prior to
// code generation ==> use the instruction as it dominates the region.
// (3) The value is an instruction:
// (a) The value was defined in the current block, thus a copy is in
// the BBMap ==> use the mapped value.
// (b) The value was defined in a previous block, thus we demoted it
// earlier ==> use the reloaded value.
Instruction *ScalarValueInst = dyn_cast<Instruction>(ScalarValue);
if (!ScalarValueInst)
return ScalarValue;
if (!R.contains(ScalarValueInst)) {
if (Value *ScalarValueCopy = GlobalMap.lookup(ScalarValueInst))
return /* Case (3a) */ ScalarValueCopy;
else
return /* Case 2 */ ScalarValue;
}
if (Value *ScalarValueCopy = BBMap.lookup(ScalarValueInst))
return /* Case (3a) */ ScalarValueCopy;
// Case (3b)
Value *Address = getOrCreateScalarAlloca(ScalarValueInst);
ScalarValue = Builder.CreateLoad(Address, Address->getName() + ".reload");
return ScalarValue;
}
void BlockGenerator::generateScalarStores(ScopStmt &Stmt, BasicBlock *BB,
ValueMapT &BBMap) {
const Region &R = Stmt.getParent()->getRegion();
assert(Stmt.isBlockStmt() && BB == Stmt.getBasicBlock() &&
"Region statements need to use the generateScalarStores() "
"function in the RegionGenerator");
for (MemoryAccess *MA : Stmt) {
if (MA->isExplicit() || MA->isRead())
continue;
Value *Val = MA->getAccessValue();
auto *Address = getOrCreateAlloca(*MA);
Val = getNewScalarValue(Val, R, BBMap);
Builder.CreateStore(Val, Address);
}
}
void BlockGenerator::createScalarInitialization(Scop &S) {
Region &R = S.getRegion();
// The split block __just before__ the region and optimized region.
BasicBlock *SplitBB = R.getEnteringBlock();
BranchInst *SplitBBTerm = cast<BranchInst>(SplitBB->getTerminator());
assert(SplitBBTerm->getNumSuccessors() == 2 && "Bad region entering block!");
// Get the start block of the __optimized__ region.
BasicBlock *StartBB = SplitBBTerm->getSuccessor(0);
if (StartBB == R.getEntry())
StartBB = SplitBBTerm->getSuccessor(1);
Builder.SetInsertPoint(StartBB->getTerminator());
for (auto &Pair : S.arrays()) {
auto &Array = Pair.second;
if (Array->getNumberOfDimensions() != 0)
continue;
if (Array->isPHI()) {
// For PHI nodes, the only values we need to store are the ones that
// reach the PHI node from outside the region. In general there should
// only be one such incoming edge and this edge should enter through
// 'SplitBB'.
auto PHI = cast<PHINode>(Array->getBasePtr());
for (auto BI = PHI->block_begin(), BE = PHI->block_end(); BI != BE; BI++)
if (!R.contains(*BI) && *BI != SplitBB)
llvm_unreachable("Incoming edges from outside the scop should always "
"come from SplitBB");
int Idx = PHI->getBasicBlockIndex(SplitBB);
if (Idx < 0)
continue;
Value *ScalarValue = PHI->getIncomingValue(Idx);
Builder.CreateStore(ScalarValue, getOrCreatePHIAlloca(PHI));
continue;
}
auto *Inst = dyn_cast<Instruction>(Array->getBasePtr());
if (Inst && R.contains(Inst))
continue;
// PHI nodes that are not marked as such in their SAI object are exit PHI
// nodes we model as common scalars but do not need to initialize.
if (Inst && isa<PHINode>(Inst))
continue;
ValueMapT EmptyMap;
Builder.CreateStore(Array->getBasePtr(),
getOrCreateScalarAlloca(Array->getBasePtr()));
}
}
void BlockGenerator::createScalarFinalization(Region &R) {
// The exit block of the __unoptimized__ region.
BasicBlock *ExitBB = R.getExitingBlock();
// The merge block __just after__ the region and the optimized region.
BasicBlock *MergeBB = R.getExit();
// The exit block of the __optimized__ region.
BasicBlock *OptExitBB = *(pred_begin(MergeBB));
if (OptExitBB == ExitBB)
OptExitBB = *(++pred_begin(MergeBB));
Builder.SetInsertPoint(OptExitBB->getTerminator());
for (const auto &EscapeMapping : EscapeMap) {
// Extract the escaping instruction and the escaping users as well as the
// alloca the instruction was demoted to.
Instruction *EscapeInst = EscapeMapping.getFirst();
const auto &EscapeMappingValue = EscapeMapping.getSecond();
const EscapeUserVectorTy &EscapeUsers = EscapeMappingValue.second;
Value *ScalarAddr = EscapeMappingValue.first;
// Reload the demoted instruction in the optimized version of the SCoP.
Instruction *EscapeInstReload =
Builder.CreateLoad(ScalarAddr, EscapeInst->getName() + ".final_reload");
// Create the merge PHI that merges the optimized and unoptimized version.
PHINode *MergePHI = PHINode::Create(EscapeInst->getType(), 2,
EscapeInst->getName() + ".merge");
MergePHI->insertBefore(MergeBB->getFirstInsertionPt());
// Add the respective values to the merge PHI.
MergePHI->addIncoming(EscapeInstReload, OptExitBB);
MergePHI->addIncoming(EscapeInst, ExitBB);
// The information of scalar evolution about the escaping instruction needs
// to be revoked so the new merged instruction will be used.
if (SE.isSCEVable(EscapeInst->getType()))
SE.forgetValue(EscapeInst);
// Replace all uses of the demoted instruction with the merge PHI.
for (Instruction *EUser : EscapeUsers)
EUser->replaceUsesOfWith(EscapeInst, MergePHI);
}
}
void BlockGenerator::finalizeSCoP(Scop &S) {
// Handle PHI nodes that were in the original exit and are now
// moved into the region exiting block.
if (!S.hasSingleExitEdge()) {
for (Instruction &I : *S.getRegion().getExitingBlock()) {
PHINode *PHI = dyn_cast<PHINode>(&I);
if (!PHI)
break;
assert(PHI->getNumUses() == 1);
assert(ScalarMap.count(PHI->user_back()));
handleOutsideUsers(S.getRegion(), PHI, nullptr,
ScalarMap[PHI->user_back()]);
}
}
createScalarInitialization(S);
createScalarFinalization(S.getRegion());
}
VectorBlockGenerator::VectorBlockGenerator(BlockGenerator &BlockGen,
std::vector<LoopToScevMapT> &VLTS,
isl_map *Schedule)
: BlockGenerator(BlockGen), VLTS(VLTS), Schedule(Schedule) {
assert(Schedule && "No statement domain provided");
}
Value *VectorBlockGenerator::getVectorValue(ScopStmt &Stmt, const Value *Old,
ValueMapT &VectorMap,
VectorValueMapT &ScalarMaps,
Loop *L) {
if (Value *NewValue = VectorMap.lookup(Old))
return NewValue;
int Width = getVectorWidth();
Value *Vector = UndefValue::get(VectorType::get(Old->getType(), Width));
for (int Lane = 0; Lane < Width; Lane++)
Vector = Builder.CreateInsertElement(
Vector, getNewValue(Stmt, Old, ScalarMaps[Lane], VLTS[Lane], L),
Builder.getInt32(Lane));
VectorMap[Old] = Vector;
return Vector;
}
Type *VectorBlockGenerator::getVectorPtrTy(const Value *Val, int Width) {
PointerType *PointerTy = dyn_cast<PointerType>(Val->getType());
assert(PointerTy && "PointerType expected");
Type *ScalarType = PointerTy->getElementType();
VectorType *VectorType = VectorType::get(ScalarType, Width);
return PointerType::getUnqual(VectorType);
}
Value *VectorBlockGenerator::generateStrideOneLoad(
ScopStmt &Stmt, const LoadInst *Load, VectorValueMapT &ScalarMaps,
__isl_keep isl_id_to_ast_expr *NewAccesses, bool NegativeStride = false) {
unsigned VectorWidth = getVectorWidth();
const Value *Pointer = Load->getPointerOperand();
Type *VectorPtrType = getVectorPtrTy(Pointer, VectorWidth);
unsigned Offset = NegativeStride ? VectorWidth - 1 : 0;
Value *NewPointer = nullptr;
NewPointer = generateLocationAccessed(Stmt, Load, Pointer, ScalarMaps[Offset],
VLTS[Offset], NewAccesses);
Value *VectorPtr =
Builder.CreateBitCast(NewPointer, VectorPtrType, "vector_ptr");
LoadInst *VecLoad =
Builder.CreateLoad(VectorPtr, Load->getName() + "_p_vec_full");
if (!Aligned)
VecLoad->setAlignment(8);
if (NegativeStride) {
SmallVector<Constant *, 16> Indices;
for (int i = VectorWidth - 1; i >= 0; i--)
Indices.push_back(ConstantInt::get(Builder.getInt32Ty(), i));
Constant *SV = llvm::ConstantVector::get(Indices);
Value *RevVecLoad = Builder.CreateShuffleVector(
VecLoad, VecLoad, SV, Load->getName() + "_reverse");
return RevVecLoad;
}
return VecLoad;
}
Value *VectorBlockGenerator::generateStrideZeroLoad(
ScopStmt &Stmt, const LoadInst *Load, ValueMapT &BBMap,
__isl_keep isl_id_to_ast_expr *NewAccesses) {
const Value *Pointer = Load->getPointerOperand();
Type *VectorPtrType = getVectorPtrTy(Pointer, 1);
Value *NewPointer = generateLocationAccessed(Stmt, Load, Pointer, BBMap,
VLTS[0], NewAccesses);
Value *VectorPtr = Builder.CreateBitCast(NewPointer, VectorPtrType,
Load->getName() + "_p_vec_p");
LoadInst *ScalarLoad =
Builder.CreateLoad(VectorPtr, Load->getName() + "_p_splat_one");
if (!Aligned)
ScalarLoad->setAlignment(8);
Constant *SplatVector = Constant::getNullValue(
VectorType::get(Builder.getInt32Ty(), getVectorWidth()));
Value *VectorLoad = Builder.CreateShuffleVector(
ScalarLoad, ScalarLoad, SplatVector, Load->getName() + "_p_splat");
return VectorLoad;
}
Value *VectorBlockGenerator::generateUnknownStrideLoad(
ScopStmt &Stmt, const LoadInst *Load, VectorValueMapT &ScalarMaps,
__isl_keep isl_id_to_ast_expr *NewAccesses
) {
int VectorWidth = getVectorWidth();
const Value *Pointer = Load->getPointerOperand();
VectorType *VectorType = VectorType::get(
dyn_cast<PointerType>(Pointer->getType())->getElementType(), VectorWidth);
Value *Vector = UndefValue::get(VectorType);
for (int i = 0; i < VectorWidth; i++) {
Value *NewPointer = generateLocationAccessed(
Stmt, Load, Pointer, ScalarMaps[i], VLTS[i], NewAccesses);
Value *ScalarLoad =
Builder.CreateLoad(NewPointer, Load->getName() + "_p_scalar_");
Vector = Builder.CreateInsertElement(
Vector, ScalarLoad, Builder.getInt32(i), Load->getName() + "_p_vec_");
}
return Vector;
}
void VectorBlockGenerator::generateLoad(
ScopStmt &Stmt, const LoadInst *Load, ValueMapT &VectorMap,
VectorValueMapT &ScalarMaps, __isl_keep isl_id_to_ast_expr *NewAccesses) {
if (!VectorType::isValidElementType(Load->getType())) {
for (int i = 0; i < getVectorWidth(); i++)
ScalarMaps[i][Load] =
generateScalarLoad(Stmt, Load, ScalarMaps[i], VLTS[i], NewAccesses);
return;
}
const MemoryAccess &Access = Stmt.getAccessFor(Load);
// Make sure we have scalar values available to access the pointer to
// the data location.
extractScalarValues(Load, VectorMap, ScalarMaps);
Value *NewLoad;
if (Access.isStrideZero(isl_map_copy(Schedule)))
NewLoad = generateStrideZeroLoad(Stmt, Load, ScalarMaps[0], NewAccesses);
else if (Access.isStrideOne(isl_map_copy(Schedule)))
NewLoad = generateStrideOneLoad(Stmt, Load, ScalarMaps, NewAccesses);
else if (Access.isStrideX(isl_map_copy(Schedule), -1))
NewLoad = generateStrideOneLoad(Stmt, Load, ScalarMaps, NewAccesses, true);
else
NewLoad = generateUnknownStrideLoad(Stmt, Load, ScalarMaps, NewAccesses);
VectorMap[Load] = NewLoad;
}
void VectorBlockGenerator::copyUnaryInst(ScopStmt &Stmt,
const UnaryInstruction *Inst,
ValueMapT &VectorMap,
VectorValueMapT &ScalarMaps) {
int VectorWidth = getVectorWidth();
Value *NewOperand = getVectorValue(Stmt, Inst->getOperand(0), VectorMap,
ScalarMaps, getLoopForInst(Inst));
assert(isa<CastInst>(Inst) && "Can not generate vector code for instruction");
const CastInst *Cast = dyn_cast<CastInst>(Inst);
VectorType *DestType = VectorType::get(Inst->getType(), VectorWidth);
VectorMap[Inst] = Builder.CreateCast(Cast->getOpcode(), NewOperand, DestType);
}
void VectorBlockGenerator::copyBinaryInst(ScopStmt &Stmt,
const BinaryOperator *Inst,
ValueMapT &VectorMap,
VectorValueMapT &ScalarMaps) {
Loop *L = getLoopForInst(Inst);
Value *OpZero = Inst->getOperand(0);
Value *OpOne = Inst->getOperand(1);
Value *NewOpZero, *NewOpOne;
NewOpZero = getVectorValue(Stmt, OpZero, VectorMap, ScalarMaps, L);
NewOpOne = getVectorValue(Stmt, OpOne, VectorMap, ScalarMaps, L);
Value *NewInst = Builder.CreateBinOp(Inst->getOpcode(), NewOpZero, NewOpOne,
Inst->getName() + "p_vec");
VectorMap[Inst] = NewInst;
}
void VectorBlockGenerator::copyStore(
ScopStmt &Stmt, const StoreInst *Store, ValueMapT &VectorMap,
VectorValueMapT &ScalarMaps, __isl_keep isl_id_to_ast_expr *NewAccesses) {
const MemoryAccess &Access = Stmt.getAccessFor(Store);
const Value *Pointer = Store->getPointerOperand();
Value *Vector = getVectorValue(Stmt, Store->getValueOperand(), VectorMap,
ScalarMaps, getLoopForInst(Store));
// Make sure we have scalar values available to access the pointer to
// the data location.
extractScalarValues(Store, VectorMap, ScalarMaps);
if (Access.isStrideOne(isl_map_copy(Schedule))) {
Type *VectorPtrType = getVectorPtrTy(Pointer, getVectorWidth());
Value *NewPointer = generateLocationAccessed(
Stmt, Store, Pointer, ScalarMaps[0], VLTS[0], NewAccesses);
Value *VectorPtr =
Builder.CreateBitCast(NewPointer, VectorPtrType, "vector_ptr");
StoreInst *Store = Builder.CreateStore(Vector, VectorPtr);
if (!Aligned)
Store->setAlignment(8);
} else {
for (unsigned i = 0; i < ScalarMaps.size(); i++) {
Value *Scalar = Builder.CreateExtractElement(Vector, Builder.getInt32(i));
Value *NewPointer = generateLocationAccessed(
Stmt, Store, Pointer, ScalarMaps[i], VLTS[i], NewAccesses);
Builder.CreateStore(Scalar, NewPointer);
}
}
}
bool VectorBlockGenerator::hasVectorOperands(const Instruction *Inst,
ValueMapT &VectorMap) {
for (Value *Operand : Inst->operands())
if (VectorMap.count(Operand))
return true;
return false;
}
bool VectorBlockGenerator::extractScalarValues(const Instruction *Inst,
ValueMapT &VectorMap,
VectorValueMapT &ScalarMaps) {
bool HasVectorOperand = false;
int VectorWidth = getVectorWidth();
for (Value *Operand : Inst->operands()) {
ValueMapT::iterator VecOp = VectorMap.find(Operand);
if (VecOp == VectorMap.end())
continue;
HasVectorOperand = true;
Value *NewVector = VecOp->second;
for (int i = 0; i < VectorWidth; ++i) {
ValueMapT &SM = ScalarMaps[i];
// If there is one scalar extracted, all scalar elements should have
// already been extracted by the code here. So no need to check for the
// existance of all of them.
if (SM.count(Operand))
break;
SM[Operand] =
Builder.CreateExtractElement(NewVector, Builder.getInt32(i));
}
}
return HasVectorOperand;
}
void VectorBlockGenerator::copyInstScalarized(
ScopStmt &Stmt, const Instruction *Inst, ValueMapT &VectorMap,
VectorValueMapT &ScalarMaps, __isl_keep isl_id_to_ast_expr *NewAccesses) {
bool HasVectorOperand;
int VectorWidth = getVectorWidth();
HasVectorOperand = extractScalarValues(Inst, VectorMap, ScalarMaps);
for (int VectorLane = 0; VectorLane < getVectorWidth(); VectorLane++)
BlockGenerator::copyInstruction(Stmt, Inst, ScalarMaps[VectorLane],
VLTS[VectorLane], NewAccesses);
if (!VectorType::isValidElementType(Inst->getType()) || !HasVectorOperand)
return;
// Make the result available as vector value.
VectorType *VectorType = VectorType::get(Inst->getType(), VectorWidth);
Value *Vector = UndefValue::get(VectorType);
for (int i = 0; i < VectorWidth; i++)
Vector = Builder.CreateInsertElement(Vector, ScalarMaps[i][Inst],
Builder.getInt32(i));
VectorMap[Inst] = Vector;
}
int VectorBlockGenerator::getVectorWidth() { return VLTS.size(); }
void VectorBlockGenerator::copyInstruction(
ScopStmt &Stmt, const Instruction *Inst, ValueMapT &VectorMap,
VectorValueMapT &ScalarMaps, __isl_keep isl_id_to_ast_expr *NewAccesses) {
// Terminator instructions control the control flow. They are explicitly
// expressed in the clast and do not need to be copied.
if (Inst->isTerminator())
return;
if (canSynthesize(Inst, &LI, &SE, &Stmt.getParent()->getRegion()))
return;
if (const LoadInst *Load = dyn_cast<LoadInst>(Inst)) {
generateLoad(Stmt, Load, VectorMap, ScalarMaps, NewAccesses);
return;
}
if (hasVectorOperands(Inst, VectorMap)) {
if (const StoreInst *Store = dyn_cast<StoreInst>(Inst)) {
copyStore(Stmt, Store, VectorMap, ScalarMaps, NewAccesses);
return;
}
if (const UnaryInstruction *Unary = dyn_cast<UnaryInstruction>(Inst)) {
copyUnaryInst(Stmt, Unary, VectorMap, ScalarMaps);
return;
}
if (const BinaryOperator *Binary = dyn_cast<BinaryOperator>(Inst)) {
copyBinaryInst(Stmt, Binary, VectorMap, ScalarMaps);
return;
}
// Falltrough: We generate scalar instructions, if we don't know how to
// generate vector code.
}
copyInstScalarized(Stmt, Inst, VectorMap, ScalarMaps, NewAccesses);
}
void VectorBlockGenerator::copyStmt(
ScopStmt &Stmt, __isl_keep isl_id_to_ast_expr *NewAccesses) {
assert(Stmt.isBlockStmt() && "TODO: Only block statements can be copied by "
"the vector block generator");
BasicBlock *BB = Stmt.getBasicBlock();
BasicBlock *CopyBB =
SplitBlock(Builder.GetInsertBlock(), Builder.GetInsertPoint(), &DT, &LI);
CopyBB->setName("polly.stmt." + BB->getName());
Builder.SetInsertPoint(CopyBB->begin());
// Create two maps that store the mapping from the original instructions of
// the old basic block to their copies in the new basic block. Those maps
// are basic block local.
//
// As vector code generation is supported there is one map for scalar values
// and one for vector values.
//
// In case we just do scalar code generation, the vectorMap is not used and
// the scalarMap has just one dimension, which contains the mapping.
//
// In case vector code generation is done, an instruction may either appear
// in the vector map once (as it is calculating >vectorwidth< values at a
// time. Or (if the values are calculated using scalar operations), it
// appears once in every dimension of the scalarMap.
VectorValueMapT ScalarBlockMap(getVectorWidth());
ValueMapT VectorBlockMap;
for (Instruction &Inst : *BB)
copyInstruction(Stmt, &Inst, VectorBlockMap, ScalarBlockMap, NewAccesses);
}
BasicBlock *RegionGenerator::repairDominance(BasicBlock *BB,
BasicBlock *BBCopy) {
BasicBlock *BBIDom = DT.getNode(BB)->getIDom()->getBlock();
BasicBlock *BBCopyIDom = BlockMap.lookup(BBIDom);
if (BBCopyIDom)
DT.changeImmediateDominator(BBCopy, BBCopyIDom);
return BBCopyIDom;
}
void RegionGenerator::copyStmt(ScopStmt &Stmt, LoopToScevMapT &LTS,
isl_id_to_ast_expr *IdToAstExp) {
assert(Stmt.isRegionStmt() &&
"Only region statements can be copied by the region generator");
// Forget all old mappings.
BlockMap.clear();
RegionMaps.clear();
IncompletePHINodeMap.clear();
// The region represented by the statement.
Region *R = Stmt.getRegion();
// Create a dedicated entry for the region where we can reload all demoted
// inputs.
BasicBlock *EntryBB = R->getEntry();
BasicBlock *EntryBBCopy =
SplitBlock(Builder.GetInsertBlock(), Builder.GetInsertPoint(), &DT, &LI);
EntryBBCopy->setName("polly.stmt." + EntryBB->getName() + ".entry");
Builder.SetInsertPoint(EntryBBCopy->begin());
for (auto PI = pred_begin(EntryBB), PE = pred_end(EntryBB); PI != PE; ++PI)
if (!R->contains(*PI))
BlockMap[*PI] = EntryBBCopy;
// Iterate over all blocks in the region in a breadth-first search.
std::deque<BasicBlock *> Blocks;
SmallPtrSet<BasicBlock *, 8> SeenBlocks;
Blocks.push_back(EntryBB);
SeenBlocks.insert(EntryBB);
while (!Blocks.empty()) {
BasicBlock *BB = Blocks.front();
Blocks.pop_front();
// First split the block and update dominance information.
BasicBlock *BBCopy = splitBB(BB);
BasicBlock *BBCopyIDom = repairDominance(BB, BBCopy);
// In order to remap PHI nodes we store also basic block mappings.
BlockMap[BB] = BBCopy;
// Get the mapping for this block and initialize it with the mapping
// available at its immediate dominator (in the new region).
ValueMapT &RegionMap = RegionMaps[BBCopy];
RegionMap = RegionMaps[BBCopyIDom];
// Copy the block with the BlockGenerator.
copyBB(Stmt, BB, BBCopy, RegionMap, LTS, IdToAstExp);
// In order to remap PHI nodes we store also basic block mappings.
BlockMap[BB] = BBCopy;
// Add values to incomplete PHI nodes waiting for this block to be copied.
for (const PHINodePairTy &PHINodePair : IncompletePHINodeMap[BB])
addOperandToPHI(Stmt, PHINodePair.first, PHINodePair.second, BB, LTS);
IncompletePHINodeMap[BB].clear();
// And continue with new successors inside the region.
for (auto SI = succ_begin(BB), SE = succ_end(BB); SI != SE; SI++)
if (R->contains(*SI) && SeenBlocks.insert(*SI).second)
Blocks.push_back(*SI);
}
// Now create a new dedicated region exit block and add it to the region map.
BasicBlock *ExitBBCopy =
SplitBlock(Builder.GetInsertBlock(), Builder.GetInsertPoint(), &DT, &LI);
ExitBBCopy->setName("polly.stmt." + R->getExit()->getName() + ".exit");
BlockMap[R->getExit()] = ExitBBCopy;
repairDominance(R->getExit(), ExitBBCopy);
// As the block generator doesn't handle control flow we need to add the
// region control flow by hand after all blocks have been copied.
for (BasicBlock *BB : SeenBlocks) {
BasicBlock *BBCopy = BlockMap[BB];
TerminatorInst *TI = BB->getTerminator();
if (isa<UnreachableInst>(TI)) {
while (!BBCopy->empty())
BBCopy->begin()->eraseFromParent();
new UnreachableInst(BBCopy->getContext(), BBCopy);
continue;
}
Instruction *BICopy = BBCopy->getTerminator();
ValueMapT &RegionMap = RegionMaps[BBCopy];
RegionMap.insert(BlockMap.begin(), BlockMap.end());
Builder.SetInsertPoint(BICopy);
copyInstScalar(Stmt, TI, RegionMap, LTS);
BICopy->eraseFromParent();
}
// Add counting PHI nodes to all loops in the region that can be used as
// replacement for SCEVs refering to the old loop.
for (BasicBlock *BB : SeenBlocks) {
Loop *L = LI.getLoopFor(BB);
if (L == nullptr || L->getHeader() != BB)
continue;
BasicBlock *BBCopy = BlockMap[BB];
Value *NullVal = Builder.getInt32(0);
PHINode *LoopPHI =
PHINode::Create(Builder.getInt32Ty(), 2, "polly.subregion.iv");
Instruction *LoopPHIInc = BinaryOperator::CreateAdd(
LoopPHI, Builder.getInt32(1), "polly.subregion.iv.inc");
LoopPHI->insertBefore(BBCopy->begin());
LoopPHIInc->insertBefore(BBCopy->getTerminator());
for (auto *PredBB : make_range(pred_begin(BB), pred_end(BB))) {
if (!R->contains(PredBB))
continue;
if (L->contains(PredBB))
LoopPHI->addIncoming(LoopPHIInc, BlockMap[PredBB]);
else
LoopPHI->addIncoming(NullVal, BlockMap[PredBB]);
}
for (auto *PredBBCopy : make_range(pred_begin(BBCopy), pred_end(BBCopy)))
if (LoopPHI->getBasicBlockIndex(PredBBCopy) < 0)
LoopPHI->addIncoming(NullVal, PredBBCopy);
LTS[L] = SE.getUnknown(LoopPHI);
}
// Reset the old insert point for the build.
Builder.SetInsertPoint(ExitBBCopy->begin());
}
void RegionGenerator::generateScalarLoads(ScopStmt &Stmt,
const Instruction *Inst,
ValueMapT &BBMap) {
// Inside a non-affine region PHI nodes are copied not demoted. Once the
// phi is copied it will reload all inputs from outside the region, hence
// we do not need to generate code for the read access of the operands of a
// PHI.
if (isa<PHINode>(Inst))
return;
return BlockGenerator::generateScalarLoads(Stmt, Inst, BBMap);
}
void RegionGenerator::generateScalarStores(ScopStmt &Stmt, BasicBlock *BB,
ValueMapT &BBMap) {
const Region &R = Stmt.getParent()->getRegion();
assert(Stmt.getRegion() &&
"Block statements need to use the generateScalarStores() "
"function in the BlockGenerator");
for (MemoryAccess *MA : Stmt) {
if (MA->isExplicit() || MA->isRead())
continue;
Instruction *ScalarInst = MA->getAccessInstruction();
// Only generate accesses that belong to this basic block.
if (ScalarInst->getParent() != BB)
continue;
Value *Val = MA->getAccessValue();
auto Address = getOrCreateAlloca(*MA);
Val = getNewScalarValue(Val, R, BBMap);
Builder.CreateStore(Val, Address);
}
}
void RegionGenerator::addOperandToPHI(ScopStmt &Stmt, const PHINode *PHI,
PHINode *PHICopy, BasicBlock *IncomingBB,
LoopToScevMapT &LTS) {
Region *StmtR = Stmt.getRegion();
// If the incoming block was not yet copied mark this PHI as incomplete.
// Once the block will be copied the incoming value will be added.
BasicBlock *BBCopy = BlockMap[IncomingBB];
if (!BBCopy) {
assert(StmtR->contains(IncomingBB) &&
"Bad incoming block for PHI in non-affine region");
IncompletePHINodeMap[IncomingBB].push_back(std::make_pair(PHI, PHICopy));
return;
}
Value *OpCopy = nullptr;
if (StmtR->contains(IncomingBB)) {
assert(RegionMaps.count(BBCopy) &&
"Incoming PHI block did not have a BBMap");
ValueMapT &BBCopyMap = RegionMaps[BBCopy];
Value *Op = PHI->getIncomingValueForBlock(IncomingBB);
OpCopy = getNewValue(Stmt, Op, BBCopyMap, LTS, getLoopForInst(PHI));
} else {
if (PHICopy->getBasicBlockIndex(BBCopy) >= 0)
return;
Value *PHIOpAddr = getOrCreatePHIAlloca(const_cast<PHINode *>(PHI));
OpCopy = new LoadInst(PHIOpAddr, PHIOpAddr->getName() + ".reload",
BlockMap[IncomingBB]->getTerminator());
}
assert(OpCopy && "Incoming PHI value was not copied properly");
assert(BBCopy && "Incoming PHI block was not copied properly");
PHICopy->addIncoming(OpCopy, BBCopy);
}
Value *RegionGenerator::copyPHIInstruction(ScopStmt &Stmt, const PHINode *PHI,
ValueMapT &BBMap,
LoopToScevMapT &LTS) {
unsigned NumIncoming = PHI->getNumIncomingValues();
PHINode *PHICopy =
Builder.CreatePHI(PHI->getType(), NumIncoming, "polly." + PHI->getName());
PHICopy->moveBefore(PHICopy->getParent()->getFirstNonPHI());
BBMap[PHI] = PHICopy;
for (unsigned u = 0; u < NumIncoming; u++)
addOperandToPHI(Stmt, PHI, PHICopy, PHI->getIncomingBlock(u), LTS);
return PHICopy;
}
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