forked from OSchip/llvm-project
1000 lines
41 KiB
C++
1000 lines
41 KiB
C++
//===-- TargetLowering.cpp - Implement the TargetLowering class -----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This implements the TargetLowering class.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Target/TargetLowering.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/MRegisterInfo.h"
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#include "llvm/CodeGen/SelectionDAG.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/Support/MathExtras.h"
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using namespace llvm;
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TargetLowering::TargetLowering(TargetMachine &tm)
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: TM(tm), TD(TM.getTargetData()) {
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assert(ISD::BUILTIN_OP_END <= 156 &&
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"Fixed size array in TargetLowering is not large enough!");
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// All operations default to being supported.
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memset(OpActions, 0, sizeof(OpActions));
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IsLittleEndian = TD.isLittleEndian();
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ShiftAmountTy = SetCCResultTy = PointerTy = getValueType(TD.getIntPtrType());
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ShiftAmtHandling = Undefined;
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memset(RegClassForVT, 0,MVT::LAST_VALUETYPE*sizeof(TargetRegisterClass*));
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memset(TargetDAGCombineArray, 0,
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sizeof(TargetDAGCombineArray)/sizeof(TargetDAGCombineArray[0]));
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maxStoresPerMemset = maxStoresPerMemcpy = maxStoresPerMemmove = 8;
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allowUnalignedMemoryAccesses = false;
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UseUnderscoreSetJmpLongJmp = false;
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IntDivIsCheap = false;
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Pow2DivIsCheap = false;
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StackPointerRegisterToSaveRestore = 0;
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SchedPreferenceInfo = SchedulingForLatency;
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}
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TargetLowering::~TargetLowering() {}
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/// setValueTypeAction - Set the action for a particular value type. This
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/// assumes an action has not already been set for this value type.
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static void SetValueTypeAction(MVT::ValueType VT,
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TargetLowering::LegalizeAction Action,
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TargetLowering &TLI,
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MVT::ValueType *TransformToType,
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TargetLowering::ValueTypeActionImpl &ValueTypeActions) {
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ValueTypeActions.setTypeAction(VT, Action);
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if (Action == TargetLowering::Promote) {
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MVT::ValueType PromoteTo;
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if (VT == MVT::f32)
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PromoteTo = MVT::f64;
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else {
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unsigned LargerReg = VT+1;
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while (!TLI.isTypeLegal((MVT::ValueType)LargerReg)) {
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++LargerReg;
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assert(MVT::isInteger((MVT::ValueType)LargerReg) &&
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"Nothing to promote to??");
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}
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PromoteTo = (MVT::ValueType)LargerReg;
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}
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assert(MVT::isInteger(VT) == MVT::isInteger(PromoteTo) &&
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MVT::isFloatingPoint(VT) == MVT::isFloatingPoint(PromoteTo) &&
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"Can only promote from int->int or fp->fp!");
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assert(VT < PromoteTo && "Must promote to a larger type!");
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TransformToType[VT] = PromoteTo;
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} else if (Action == TargetLowering::Expand) {
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assert((VT == MVT::Vector || MVT::isInteger(VT)) && VT > MVT::i8 &&
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"Cannot expand this type: target must support SOME integer reg!");
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// Expand to the next smaller integer type!
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TransformToType[VT] = (MVT::ValueType)(VT-1);
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}
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}
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/// computeRegisterProperties - Once all of the register classes are added,
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/// this allows us to compute derived properties we expose.
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void TargetLowering::computeRegisterProperties() {
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assert(MVT::LAST_VALUETYPE <= 32 &&
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"Too many value types for ValueTypeActions to hold!");
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// Everything defaults to one.
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for (unsigned i = 0; i != MVT::LAST_VALUETYPE; ++i)
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NumElementsForVT[i] = 1;
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// Find the largest integer register class.
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unsigned LargestIntReg = MVT::i128;
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for (; RegClassForVT[LargestIntReg] == 0; --LargestIntReg)
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assert(LargestIntReg != MVT::i1 && "No integer registers defined!");
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// Every integer value type larger than this largest register takes twice as
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// many registers to represent as the previous ValueType.
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unsigned ExpandedReg = LargestIntReg; ++LargestIntReg;
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for (++ExpandedReg; MVT::isInteger((MVT::ValueType)ExpandedReg);++ExpandedReg)
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NumElementsForVT[ExpandedReg] = 2*NumElementsForVT[ExpandedReg-1];
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// Inspect all of the ValueType's possible, deciding how to process them.
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for (unsigned IntReg = MVT::i1; IntReg <= MVT::i128; ++IntReg)
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// If we are expanding this type, expand it!
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if (getNumElements((MVT::ValueType)IntReg) != 1)
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SetValueTypeAction((MVT::ValueType)IntReg, Expand, *this, TransformToType,
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ValueTypeActions);
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else if (!isTypeLegal((MVT::ValueType)IntReg))
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// Otherwise, if we don't have native support, we must promote to a
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// larger type.
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SetValueTypeAction((MVT::ValueType)IntReg, Promote, *this,
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TransformToType, ValueTypeActions);
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else
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TransformToType[(MVT::ValueType)IntReg] = (MVT::ValueType)IntReg;
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// If the target does not have native support for F32, promote it to F64.
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if (!isTypeLegal(MVT::f32))
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SetValueTypeAction(MVT::f32, Promote, *this,
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TransformToType, ValueTypeActions);
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else
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TransformToType[MVT::f32] = MVT::f32;
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// Set MVT::Vector to always be Expanded
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SetValueTypeAction(MVT::Vector, Expand, *this, TransformToType,
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ValueTypeActions);
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// Loop over all of the legal vector value types, specifying an identity type
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// transformation.
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for (unsigned i = MVT::FIRST_VECTOR_VALUETYPE;
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i != MVT::LAST_VECTOR_VALUETYPE; ++i) {
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if (isTypeLegal((MVT::ValueType)i))
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TransformToType[i] = (MVT::ValueType)i;
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}
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assert(isTypeLegal(MVT::f64) && "Target does not support FP?");
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TransformToType[MVT::f64] = MVT::f64;
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}
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const char *TargetLowering::getTargetNodeName(unsigned Opcode) const {
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return NULL;
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}
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//===----------------------------------------------------------------------===//
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// Optimization Methods
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//===----------------------------------------------------------------------===//
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/// ShrinkDemandedConstant - Check to see if the specified operand of the
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/// specified instruction is a constant integer. If so, check to see if there
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/// are any bits set in the constant that are not demanded. If so, shrink the
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/// constant and return true.
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bool TargetLowering::TargetLoweringOpt::ShrinkDemandedConstant(SDOperand Op,
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uint64_t Demanded) {
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// FIXME: ISD::SELECT, ISD::SELECT_CC
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switch(Op.getOpcode()) {
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default: break;
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case ISD::AND:
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case ISD::OR:
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case ISD::XOR:
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if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1)))
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if ((~Demanded & C->getValue()) != 0) {
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MVT::ValueType VT = Op.getValueType();
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SDOperand New = DAG.getNode(Op.getOpcode(), VT, Op.getOperand(0),
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DAG.getConstant(Demanded & C->getValue(),
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VT));
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return CombineTo(Op, New);
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}
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break;
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}
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return false;
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}
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/// SimplifyDemandedBits - Look at Op. At this point, we know that only the
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/// DemandedMask bits of the result of Op are ever used downstream. If we can
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/// use this information to simplify Op, create a new simplified DAG node and
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/// return true, returning the original and new nodes in Old and New. Otherwise,
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/// analyze the expression and return a mask of KnownOne and KnownZero bits for
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/// the expression (used to simplify the caller). The KnownZero/One bits may
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/// only be accurate for those bits in the DemandedMask.
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bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
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uint64_t &KnownZero,
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uint64_t &KnownOne,
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TargetLoweringOpt &TLO,
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unsigned Depth) const {
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KnownZero = KnownOne = 0; // Don't know anything.
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// Other users may use these bits.
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if (!Op.Val->hasOneUse()) {
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if (Depth != 0) {
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// If not at the root, Just compute the KnownZero/KnownOne bits to
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// simplify things downstream.
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ComputeMaskedBits(Op, DemandedMask, KnownZero, KnownOne, Depth);
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return false;
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}
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// If this is the root being simplified, allow it to have multiple uses,
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// just set the DemandedMask to all bits.
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DemandedMask = MVT::getIntVTBitMask(Op.getValueType());
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} else if (DemandedMask == 0) {
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// Not demanding any bits from Op.
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if (Op.getOpcode() != ISD::UNDEF)
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return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::UNDEF, Op.getValueType()));
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return false;
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} else if (Depth == 6) { // Limit search depth.
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return false;
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}
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uint64_t KnownZero2, KnownOne2, KnownZeroOut, KnownOneOut;
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switch (Op.getOpcode()) {
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case ISD::Constant:
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// We know all of the bits for a constant!
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KnownOne = cast<ConstantSDNode>(Op)->getValue() & DemandedMask;
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KnownZero = ~KnownOne & DemandedMask;
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return false; // Don't fall through, will infinitely loop.
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case ISD::AND:
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// If the RHS is a constant, check to see if the LHS would be zero without
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// using the bits from the RHS. Below, we use knowledge about the RHS to
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// simplify the LHS, here we're using information from the LHS to simplify
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// the RHS.
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if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
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uint64_t LHSZero, LHSOne;
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ComputeMaskedBits(Op.getOperand(0), DemandedMask,
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LHSZero, LHSOne, Depth+1);
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// If the LHS already has zeros where RHSC does, this and is dead.
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if ((LHSZero & DemandedMask) == (~RHSC->getValue() & DemandedMask))
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return TLO.CombineTo(Op, Op.getOperand(0));
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// If any of the set bits in the RHS are known zero on the LHS, shrink
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// the constant.
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if (TLO.ShrinkDemandedConstant(Op, ~LHSZero & DemandedMask))
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return true;
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}
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if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero,
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KnownOne, TLO, Depth+1))
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return true;
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & ~KnownZero,
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KnownZero2, KnownOne2, TLO, Depth+1))
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return true;
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assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
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// If all of the demanded bits are known one on one side, return the other.
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// These bits cannot contribute to the result of the 'and'.
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if ((DemandedMask & ~KnownZero2 & KnownOne)==(DemandedMask & ~KnownZero2))
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return TLO.CombineTo(Op, Op.getOperand(0));
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if ((DemandedMask & ~KnownZero & KnownOne2)==(DemandedMask & ~KnownZero))
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return TLO.CombineTo(Op, Op.getOperand(1));
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// If all of the demanded bits in the inputs are known zeros, return zero.
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if ((DemandedMask & (KnownZero|KnownZero2)) == DemandedMask)
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return TLO.CombineTo(Op, TLO.DAG.getConstant(0, Op.getValueType()));
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// If the RHS is a constant, see if we can simplify it.
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if (TLO.ShrinkDemandedConstant(Op, DemandedMask & ~KnownZero2))
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return true;
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// Output known-1 bits are only known if set in both the LHS & RHS.
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KnownOne &= KnownOne2;
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// Output known-0 are known to be clear if zero in either the LHS | RHS.
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KnownZero |= KnownZero2;
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break;
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case ISD::OR:
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if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero,
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KnownOne, TLO, Depth+1))
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return true;
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & ~KnownOne,
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KnownZero2, KnownOne2, TLO, Depth+1))
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return true;
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assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
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// If all of the demanded bits are known zero on one side, return the other.
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// These bits cannot contribute to the result of the 'or'.
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if ((DemandedMask & ~KnownOne2 & KnownZero) == (DemandedMask & ~KnownOne2))
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return TLO.CombineTo(Op, Op.getOperand(0));
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if ((DemandedMask & ~KnownOne & KnownZero2) == (DemandedMask & ~KnownOne))
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return TLO.CombineTo(Op, Op.getOperand(1));
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// If all of the potentially set bits on one side are known to be set on
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// the other side, just use the 'other' side.
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if ((DemandedMask & (~KnownZero) & KnownOne2) ==
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(DemandedMask & (~KnownZero)))
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return TLO.CombineTo(Op, Op.getOperand(0));
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if ((DemandedMask & (~KnownZero2) & KnownOne) ==
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(DemandedMask & (~KnownZero2)))
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return TLO.CombineTo(Op, Op.getOperand(1));
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// If the RHS is a constant, see if we can simplify it.
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if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
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return true;
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// Output known-0 bits are only known if clear in both the LHS & RHS.
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KnownZero &= KnownZero2;
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// Output known-1 are known to be set if set in either the LHS | RHS.
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KnownOne |= KnownOne2;
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break;
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case ISD::XOR:
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if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero,
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KnownOne, TLO, Depth+1))
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return true;
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask, KnownZero2,
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KnownOne2, TLO, Depth+1))
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return true;
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assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
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// If all of the demanded bits are known zero on one side, return the other.
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// These bits cannot contribute to the result of the 'xor'.
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if ((DemandedMask & KnownZero) == DemandedMask)
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return TLO.CombineTo(Op, Op.getOperand(0));
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if ((DemandedMask & KnownZero2) == DemandedMask)
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return TLO.CombineTo(Op, Op.getOperand(1));
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// Output known-0 bits are known if clear or set in both the LHS & RHS.
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KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
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// Output known-1 are known to be set if set in only one of the LHS, RHS.
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KnownOneOut = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
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// If all of the unknown bits are known to be zero on one side or the other
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// (but not both) turn this into an *inclusive* or.
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// e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
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if (uint64_t UnknownBits = DemandedMask & ~(KnownZeroOut|KnownOneOut))
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if ((UnknownBits & (KnownZero|KnownZero2)) == UnknownBits)
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return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::OR, Op.getValueType(),
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Op.getOperand(0),
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Op.getOperand(1)));
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// If all of the demanded bits on one side are known, and all of the set
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// bits on that side are also known to be set on the other side, turn this
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// into an AND, as we know the bits will be cleared.
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// e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
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if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask) { // all known
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if ((KnownOne & KnownOne2) == KnownOne) {
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MVT::ValueType VT = Op.getValueType();
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SDOperand ANDC = TLO.DAG.getConstant(~KnownOne & DemandedMask, VT);
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return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::AND, VT, Op.getOperand(0),
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ANDC));
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}
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}
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// If the RHS is a constant, see if we can simplify it.
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// FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
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if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
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return true;
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KnownZero = KnownZeroOut;
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KnownOne = KnownOneOut;
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break;
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case ISD::SETCC:
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// If we know the result of a setcc has the top bits zero, use this info.
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if (getSetCCResultContents() == TargetLowering::ZeroOrOneSetCCResult)
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KnownZero |= (MVT::getIntVTBitMask(Op.getValueType()) ^ 1ULL);
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break;
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case ISD::SELECT:
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if (SimplifyDemandedBits(Op.getOperand(2), DemandedMask, KnownZero,
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KnownOne, TLO, Depth+1))
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return true;
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if (SimplifyDemandedBits(Op.getOperand(1), DemandedMask, KnownZero2,
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KnownOne2, TLO, Depth+1))
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return true;
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
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// If the operands are constants, see if we can simplify them.
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if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
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return true;
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// Only known if known in both the LHS and RHS.
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KnownOne &= KnownOne2;
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KnownZero &= KnownZero2;
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break;
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case ISD::SELECT_CC:
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if (SimplifyDemandedBits(Op.getOperand(3), DemandedMask, KnownZero,
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KnownOne, TLO, Depth+1))
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return true;
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if (SimplifyDemandedBits(Op.getOperand(2), DemandedMask, KnownZero2,
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KnownOne2, TLO, Depth+1))
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return true;
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
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// If the operands are constants, see if we can simplify them.
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if (TLO.ShrinkDemandedConstant(Op, DemandedMask))
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return true;
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// Only known if known in both the LHS and RHS.
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KnownOne &= KnownOne2;
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KnownZero &= KnownZero2;
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break;
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case ISD::SHL:
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if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
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if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask >> SA->getValue(),
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KnownZero, KnownOne, TLO, Depth+1))
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return true;
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KnownZero <<= SA->getValue();
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KnownOne <<= SA->getValue();
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KnownZero |= (1ULL << SA->getValue())-1; // low bits known zero.
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}
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break;
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case ISD::SRL:
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if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
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MVT::ValueType VT = Op.getValueType();
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unsigned ShAmt = SA->getValue();
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// Compute the new bits that are at the top now.
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uint64_t HighBits = (1ULL << ShAmt)-1;
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HighBits <<= MVT::getSizeInBits(VT) - ShAmt;
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uint64_t TypeMask = MVT::getIntVTBitMask(VT);
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if (SimplifyDemandedBits(Op.getOperand(0),
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(DemandedMask << ShAmt) & TypeMask,
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KnownZero, KnownOne, TLO, Depth+1))
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return true;
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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KnownZero &= TypeMask;
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KnownOne &= TypeMask;
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KnownZero >>= ShAmt;
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KnownOne >>= ShAmt;
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KnownZero |= HighBits; // high bits known zero.
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}
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break;
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case ISD::SRA:
|
|
if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
|
|
MVT::ValueType VT = Op.getValueType();
|
|
unsigned ShAmt = SA->getValue();
|
|
|
|
// Compute the new bits that are at the top now.
|
|
uint64_t HighBits = (1ULL << ShAmt)-1;
|
|
HighBits <<= MVT::getSizeInBits(VT) - ShAmt;
|
|
uint64_t TypeMask = MVT::getIntVTBitMask(VT);
|
|
|
|
if (SimplifyDemandedBits(Op.getOperand(0),
|
|
(DemandedMask << ShAmt) & TypeMask,
|
|
KnownZero, KnownOne, TLO, Depth+1))
|
|
return true;
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
KnownZero &= TypeMask;
|
|
KnownOne &= TypeMask;
|
|
KnownZero >>= SA->getValue();
|
|
KnownOne >>= SA->getValue();
|
|
|
|
// Handle the sign bits.
|
|
uint64_t SignBit = MVT::getIntVTSignBit(VT);
|
|
SignBit >>= SA->getValue(); // Adjust to where it is now in the mask.
|
|
|
|
// If the input sign bit is known to be zero, or if none of the top bits
|
|
// are demanded, turn this into an unsigned shift right.
|
|
if ((KnownZero & SignBit) || (HighBits & ~DemandedMask) == HighBits) {
|
|
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL, VT, Op.getOperand(0),
|
|
Op.getOperand(1)));
|
|
} else if (KnownOne & SignBit) { // New bits are known one.
|
|
KnownOne |= HighBits;
|
|
}
|
|
}
|
|
break;
|
|
case ISD::SIGN_EXTEND_INREG: {
|
|
MVT::ValueType VT = Op.getValueType();
|
|
MVT::ValueType EVT = cast<VTSDNode>(Op.getOperand(1))->getVT();
|
|
|
|
// Sign extension. Compute the demanded bits in the result that are not
|
|
// present in the input.
|
|
uint64_t NewBits = ~MVT::getIntVTBitMask(EVT) & DemandedMask;
|
|
|
|
// If none of the extended bits are demanded, eliminate the sextinreg.
|
|
if (NewBits == 0)
|
|
return TLO.CombineTo(Op, Op.getOperand(0));
|
|
|
|
uint64_t InSignBit = MVT::getIntVTSignBit(EVT);
|
|
int64_t InputDemandedBits = DemandedMask & MVT::getIntVTBitMask(EVT);
|
|
|
|
// Since the sign extended bits are demanded, we know that the sign
|
|
// bit is demanded.
|
|
InputDemandedBits |= InSignBit;
|
|
|
|
if (SimplifyDemandedBits(Op.getOperand(0), InputDemandedBits,
|
|
KnownZero, KnownOne, TLO, Depth+1))
|
|
return true;
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
|
|
// If the sign bit of the input is known set or clear, then we know the
|
|
// top bits of the result.
|
|
|
|
// If the input sign bit is known zero, convert this into a zero extension.
|
|
if (KnownZero & InSignBit)
|
|
return TLO.CombineTo(Op,
|
|
TLO.DAG.getZeroExtendInReg(Op.getOperand(0), EVT));
|
|
|
|
if (KnownOne & InSignBit) { // Input sign bit known set
|
|
KnownOne |= NewBits;
|
|
KnownZero &= ~NewBits;
|
|
} else { // Input sign bit unknown
|
|
KnownZero &= ~NewBits;
|
|
KnownOne &= ~NewBits;
|
|
}
|
|
break;
|
|
}
|
|
case ISD::CTTZ:
|
|
case ISD::CTLZ:
|
|
case ISD::CTPOP: {
|
|
MVT::ValueType VT = Op.getValueType();
|
|
unsigned LowBits = Log2_32(MVT::getSizeInBits(VT))+1;
|
|
KnownZero = ~((1ULL << LowBits)-1) & MVT::getIntVTBitMask(VT);
|
|
KnownOne = 0;
|
|
break;
|
|
}
|
|
case ISD::ZEXTLOAD: {
|
|
MVT::ValueType VT = cast<VTSDNode>(Op.getOperand(3))->getVT();
|
|
KnownZero |= ~MVT::getIntVTBitMask(VT) & DemandedMask;
|
|
break;
|
|
}
|
|
case ISD::ZERO_EXTEND: {
|
|
uint64_t InMask = MVT::getIntVTBitMask(Op.getOperand(0).getValueType());
|
|
|
|
// If none of the top bits are demanded, convert this into an any_extend.
|
|
uint64_t NewBits = (~InMask) & DemandedMask;
|
|
if (NewBits == 0)
|
|
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::ANY_EXTEND,
|
|
Op.getValueType(),
|
|
Op.getOperand(0)));
|
|
|
|
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & InMask,
|
|
KnownZero, KnownOne, TLO, Depth+1))
|
|
return true;
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
KnownZero |= NewBits;
|
|
break;
|
|
}
|
|
case ISD::SIGN_EXTEND: {
|
|
MVT::ValueType InVT = Op.getOperand(0).getValueType();
|
|
uint64_t InMask = MVT::getIntVTBitMask(InVT);
|
|
uint64_t InSignBit = MVT::getIntVTSignBit(InVT);
|
|
uint64_t NewBits = (~InMask) & DemandedMask;
|
|
|
|
// If none of the top bits are demanded, convert this into an any_extend.
|
|
if (NewBits == 0)
|
|
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::ANY_EXTEND,Op.getValueType(),
|
|
Op.getOperand(0)));
|
|
|
|
// Since some of the sign extended bits are demanded, we know that the sign
|
|
// bit is demanded.
|
|
uint64_t InDemandedBits = DemandedMask & InMask;
|
|
InDemandedBits |= InSignBit;
|
|
|
|
if (SimplifyDemandedBits(Op.getOperand(0), InDemandedBits, KnownZero,
|
|
KnownOne, TLO, Depth+1))
|
|
return true;
|
|
|
|
// If the sign bit is known zero, convert this to a zero extend.
|
|
if (KnownZero & InSignBit)
|
|
return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::ZERO_EXTEND,
|
|
Op.getValueType(),
|
|
Op.getOperand(0)));
|
|
|
|
// If the sign bit is known one, the top bits match.
|
|
if (KnownOne & InSignBit) {
|
|
KnownOne |= NewBits;
|
|
KnownZero &= ~NewBits;
|
|
} else { // Otherwise, top bits aren't known.
|
|
KnownOne &= ~NewBits;
|
|
KnownZero &= ~NewBits;
|
|
}
|
|
break;
|
|
}
|
|
case ISD::ANY_EXTEND: {
|
|
uint64_t InMask = MVT::getIntVTBitMask(Op.getOperand(0).getValueType());
|
|
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & InMask,
|
|
KnownZero, KnownOne, TLO, Depth+1))
|
|
return true;
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
break;
|
|
}
|
|
case ISD::AssertZext: {
|
|
MVT::ValueType VT = cast<VTSDNode>(Op.getOperand(1))->getVT();
|
|
uint64_t InMask = MVT::getIntVTBitMask(VT);
|
|
if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask & InMask,
|
|
KnownZero, KnownOne, TLO, Depth+1))
|
|
return true;
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
KnownZero |= ~InMask & DemandedMask;
|
|
break;
|
|
}
|
|
case ISD::ADD:
|
|
case ISD::SUB:
|
|
// Just use ComputeMaskedBits to compute output bits, there are no
|
|
// simplifications that can be done here, and sub always demands all input
|
|
// bits.
|
|
ComputeMaskedBits(Op, DemandedMask, KnownZero, KnownOne, Depth);
|
|
break;
|
|
}
|
|
|
|
// If we know the value of all of the demanded bits, return this as a
|
|
// constant.
|
|
if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask)
|
|
return TLO.CombineTo(Op, TLO.DAG.getConstant(KnownOne, Op.getValueType()));
|
|
|
|
return false;
|
|
}
|
|
|
|
/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
|
|
/// this predicate to simplify operations downstream. Mask is known to be zero
|
|
/// for bits that V cannot have.
|
|
bool TargetLowering::MaskedValueIsZero(SDOperand Op, uint64_t Mask,
|
|
unsigned Depth) const {
|
|
uint64_t KnownZero, KnownOne;
|
|
ComputeMaskedBits(Op, Mask, KnownZero, KnownOne, Depth);
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
return (KnownZero & Mask) == Mask;
|
|
}
|
|
|
|
/// ComputeMaskedBits - Determine which of the bits specified in Mask are
|
|
/// known to be either zero or one and return them in the KnownZero/KnownOne
|
|
/// bitsets. This code only analyzes bits in Mask, in order to short-circuit
|
|
/// processing.
|
|
void TargetLowering::ComputeMaskedBits(SDOperand Op, uint64_t Mask,
|
|
uint64_t &KnownZero, uint64_t &KnownOne,
|
|
unsigned Depth) const {
|
|
KnownZero = KnownOne = 0; // Don't know anything.
|
|
if (Depth == 6 || Mask == 0)
|
|
return; // Limit search depth.
|
|
|
|
uint64_t KnownZero2, KnownOne2;
|
|
|
|
switch (Op.getOpcode()) {
|
|
case ISD::Constant:
|
|
// We know all of the bits for a constant!
|
|
KnownOne = cast<ConstantSDNode>(Op)->getValue() & Mask;
|
|
KnownZero = ~KnownOne & Mask;
|
|
return;
|
|
case ISD::AND:
|
|
// If either the LHS or the RHS are Zero, the result is zero.
|
|
ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
|
|
Mask &= ~KnownZero;
|
|
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
|
|
|
|
// Output known-1 bits are only known if set in both the LHS & RHS.
|
|
KnownOne &= KnownOne2;
|
|
// Output known-0 are known to be clear if zero in either the LHS | RHS.
|
|
KnownZero |= KnownZero2;
|
|
return;
|
|
case ISD::OR:
|
|
ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
|
|
Mask &= ~KnownOne;
|
|
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
|
|
|
|
// Output known-0 bits are only known if clear in both the LHS & RHS.
|
|
KnownZero &= KnownZero2;
|
|
// Output known-1 are known to be set if set in either the LHS | RHS.
|
|
KnownOne |= KnownOne2;
|
|
return;
|
|
case ISD::XOR: {
|
|
ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
|
|
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
|
|
|
|
// Output known-0 bits are known if clear or set in both the LHS & RHS.
|
|
uint64_t KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
|
|
// Output known-1 are known to be set if set in only one of the LHS, RHS.
|
|
KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
|
|
KnownZero = KnownZeroOut;
|
|
return;
|
|
}
|
|
case ISD::SELECT:
|
|
ComputeMaskedBits(Op.getOperand(2), Mask, KnownZero, KnownOne, Depth+1);
|
|
ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero2, KnownOne2, Depth+1);
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
|
|
|
|
// Only known if known in both the LHS and RHS.
|
|
KnownOne &= KnownOne2;
|
|
KnownZero &= KnownZero2;
|
|
return;
|
|
case ISD::SELECT_CC:
|
|
ComputeMaskedBits(Op.getOperand(3), Mask, KnownZero, KnownOne, Depth+1);
|
|
ComputeMaskedBits(Op.getOperand(2), Mask, KnownZero2, KnownOne2, Depth+1);
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
|
|
|
|
// Only known if known in both the LHS and RHS.
|
|
KnownOne &= KnownOne2;
|
|
KnownZero &= KnownZero2;
|
|
return;
|
|
case ISD::SETCC:
|
|
// If we know the result of a setcc has the top bits zero, use this info.
|
|
if (getSetCCResultContents() == TargetLowering::ZeroOrOneSetCCResult)
|
|
KnownZero |= (MVT::getIntVTBitMask(Op.getValueType()) ^ 1ULL);
|
|
return;
|
|
case ISD::SHL:
|
|
// (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
|
|
if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
|
|
Mask >>= SA->getValue();
|
|
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
KnownZero <<= SA->getValue();
|
|
KnownOne <<= SA->getValue();
|
|
KnownZero |= (1ULL << SA->getValue())-1; // low bits known zero.
|
|
}
|
|
return;
|
|
case ISD::SRL:
|
|
// (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
|
|
if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
|
|
uint64_t HighBits = (1ULL << SA->getValue())-1;
|
|
HighBits <<= MVT::getSizeInBits(Op.getValueType())-SA->getValue();
|
|
Mask <<= SA->getValue();
|
|
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
KnownZero >>= SA->getValue();
|
|
KnownOne >>= SA->getValue();
|
|
KnownZero |= HighBits; // high bits known zero.
|
|
}
|
|
return;
|
|
case ISD::SRA:
|
|
if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
|
|
uint64_t HighBits = (1ULL << SA->getValue())-1;
|
|
HighBits <<= MVT::getSizeInBits(Op.getValueType())-SA->getValue();
|
|
Mask <<= SA->getValue();
|
|
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
|
|
assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
|
|
KnownZero >>= SA->getValue();
|
|
KnownOne >>= SA->getValue();
|
|
|
|
// Handle the sign bits.
|
|
uint64_t SignBit = 1ULL << (MVT::getSizeInBits(Op.getValueType())-1);
|
|
SignBit >>= SA->getValue(); // Adjust to where it is now in the mask.
|
|
|
|
if (KnownZero & SignBit) { // New bits are known zero.
|
|
KnownZero |= HighBits;
|
|
} else if (KnownOne & SignBit) { // New bits are known one.
|
|
KnownOne |= HighBits;
|
|
}
|
|
}
|
|
return;
|
|
case ISD::SIGN_EXTEND_INREG: {
|
|
MVT::ValueType VT = Op.getValueType();
|
|
MVT::ValueType EVT = cast<VTSDNode>(Op.getOperand(1))->getVT();
|
|
|
|
// Sign extension. Compute the demanded bits in the result that are not
|
|
// present in the input.
|
|
uint64_t NewBits = ~MVT::getIntVTBitMask(EVT) & Mask;
|
|
|
|
uint64_t InSignBit = MVT::getIntVTSignBit(EVT);
|
|
int64_t InputDemandedBits = Mask & MVT::getIntVTBitMask(EVT);
|
|
|
|
// If the sign extended bits are demanded, we know that the sign
|
|
// bit is demanded.
|
|
if (NewBits)
|
|
InputDemandedBits |= InSignBit;
|
|
|
|
ComputeMaskedBits(Op.getOperand(0), InputDemandedBits,
|
|
KnownZero, KnownOne, Depth+1);
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
|
|
// If the sign bit of the input is known set or clear, then we know the
|
|
// top bits of the result.
|
|
if (KnownZero & InSignBit) { // Input sign bit known clear
|
|
KnownZero |= NewBits;
|
|
KnownOne &= ~NewBits;
|
|
} else if (KnownOne & InSignBit) { // Input sign bit known set
|
|
KnownOne |= NewBits;
|
|
KnownZero &= ~NewBits;
|
|
} else { // Input sign bit unknown
|
|
KnownZero &= ~NewBits;
|
|
KnownOne &= ~NewBits;
|
|
}
|
|
return;
|
|
}
|
|
case ISD::CTTZ:
|
|
case ISD::CTLZ:
|
|
case ISD::CTPOP: {
|
|
MVT::ValueType VT = Op.getValueType();
|
|
unsigned LowBits = Log2_32(MVT::getSizeInBits(VT))+1;
|
|
KnownZero = ~((1ULL << LowBits)-1) & MVT::getIntVTBitMask(VT);
|
|
KnownOne = 0;
|
|
return;
|
|
}
|
|
case ISD::ZEXTLOAD: {
|
|
MVT::ValueType VT = cast<VTSDNode>(Op.getOperand(3))->getVT();
|
|
KnownZero |= ~MVT::getIntVTBitMask(VT) & Mask;
|
|
return;
|
|
}
|
|
case ISD::ZERO_EXTEND: {
|
|
uint64_t InMask = MVT::getIntVTBitMask(Op.getOperand(0).getValueType());
|
|
uint64_t NewBits = (~InMask) & Mask;
|
|
ComputeMaskedBits(Op.getOperand(0), Mask & InMask, KnownZero,
|
|
KnownOne, Depth+1);
|
|
KnownZero |= NewBits & Mask;
|
|
KnownOne &= ~NewBits;
|
|
return;
|
|
}
|
|
case ISD::SIGN_EXTEND: {
|
|
MVT::ValueType InVT = Op.getOperand(0).getValueType();
|
|
unsigned InBits = MVT::getSizeInBits(InVT);
|
|
uint64_t InMask = MVT::getIntVTBitMask(InVT);
|
|
uint64_t InSignBit = 1ULL << (InBits-1);
|
|
uint64_t NewBits = (~InMask) & Mask;
|
|
uint64_t InDemandedBits = Mask & InMask;
|
|
|
|
// If any of the sign extended bits are demanded, we know that the sign
|
|
// bit is demanded.
|
|
if (NewBits & Mask)
|
|
InDemandedBits |= InSignBit;
|
|
|
|
ComputeMaskedBits(Op.getOperand(0), InDemandedBits, KnownZero,
|
|
KnownOne, Depth+1);
|
|
// If the sign bit is known zero or one, the top bits match.
|
|
if (KnownZero & InSignBit) {
|
|
KnownZero |= NewBits;
|
|
KnownOne &= ~NewBits;
|
|
} else if (KnownOne & InSignBit) {
|
|
KnownOne |= NewBits;
|
|
KnownZero &= ~NewBits;
|
|
} else { // Otherwise, top bits aren't known.
|
|
KnownOne &= ~NewBits;
|
|
KnownZero &= ~NewBits;
|
|
}
|
|
return;
|
|
}
|
|
case ISD::ANY_EXTEND: {
|
|
MVT::ValueType VT = Op.getOperand(0).getValueType();
|
|
ComputeMaskedBits(Op.getOperand(0), Mask & MVT::getIntVTBitMask(VT),
|
|
KnownZero, KnownOne, Depth+1);
|
|
return;
|
|
}
|
|
case ISD::AssertZext: {
|
|
MVT::ValueType VT = cast<VTSDNode>(Op.getOperand(1))->getVT();
|
|
uint64_t InMask = MVT::getIntVTBitMask(VT);
|
|
ComputeMaskedBits(Op.getOperand(0), Mask & InMask, KnownZero,
|
|
KnownOne, Depth+1);
|
|
KnownZero |= (~InMask) & Mask;
|
|
return;
|
|
}
|
|
case ISD::ADD: {
|
|
// If either the LHS or the RHS are Zero, the result is zero.
|
|
ComputeMaskedBits(Op.getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
|
|
ComputeMaskedBits(Op.getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
|
|
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
|
|
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
|
|
|
|
// Output known-0 bits are known if clear or set in both the low clear bits
|
|
// common to both LHS & RHS. For example, 8+(X<<3) is known to have the
|
|
// low 3 bits clear.
|
|
uint64_t KnownZeroOut = std::min(CountTrailingZeros_64(~KnownZero),
|
|
CountTrailingZeros_64(~KnownZero2));
|
|
|
|
KnownZero = (1ULL << KnownZeroOut) - 1;
|
|
KnownOne = 0;
|
|
return;
|
|
}
|
|
case ISD::SUB: {
|
|
ConstantSDNode *CLHS = dyn_cast<ConstantSDNode>(Op.getOperand(0));
|
|
if (!CLHS) return;
|
|
|
|
// We know that the top bits of C-X are clear if X contains less bits
|
|
// than C (i.e. no wrap-around can happen). For example, 20-X is
|
|
// positive if we can prove that X is >= 0 and < 16.
|
|
MVT::ValueType VT = CLHS->getValueType(0);
|
|
if ((CLHS->getValue() & MVT::getIntVTSignBit(VT)) == 0) { // sign bit clear
|
|
unsigned NLZ = CountLeadingZeros_64(CLHS->getValue()+1);
|
|
uint64_t MaskV = (1ULL << (63-NLZ))-1; // NLZ can't be 64 with no sign bit
|
|
MaskV = ~MaskV & MVT::getIntVTBitMask(VT);
|
|
ComputeMaskedBits(Op.getOperand(1), MaskV, KnownZero, KnownOne, Depth+1);
|
|
|
|
// If all of the MaskV bits are known to be zero, then we know the output
|
|
// top bits are zero, because we now know that the output is from [0-C].
|
|
if ((KnownZero & MaskV) == MaskV) {
|
|
unsigned NLZ2 = CountLeadingZeros_64(CLHS->getValue());
|
|
KnownZero = ~((1ULL << (64-NLZ2))-1) & Mask; // Top bits known zero.
|
|
KnownOne = 0; // No one bits known.
|
|
} else {
|
|
KnownOne = KnownOne = 0; // Otherwise, nothing known.
|
|
}
|
|
}
|
|
return;
|
|
}
|
|
default:
|
|
// Allow the target to implement this method for its nodes.
|
|
if (Op.getOpcode() >= ISD::BUILTIN_OP_END)
|
|
computeMaskedBitsForTargetNode(Op, Mask, KnownZero, KnownOne);
|
|
return;
|
|
}
|
|
}
|
|
|
|
/// computeMaskedBitsForTargetNode - Determine which of the bits specified
|
|
/// in Mask are known to be either zero or one and return them in the
|
|
/// KnownZero/KnownOne bitsets.
|
|
void TargetLowering::computeMaskedBitsForTargetNode(const SDOperand Op,
|
|
uint64_t Mask,
|
|
uint64_t &KnownZero,
|
|
uint64_t &KnownOne,
|
|
unsigned Depth) const {
|
|
assert(Op.getOpcode() >= ISD::BUILTIN_OP_END &&
|
|
"Should use MaskedValueIsZero if you don't know whether Op"
|
|
" is a target node!");
|
|
KnownZero = 0;
|
|
KnownOne = 0;
|
|
}
|
|
|
|
SDOperand TargetLowering::
|
|
PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const {
|
|
// Default implementation: no optimization.
|
|
return SDOperand();
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Inline Assembler Implementation Methods
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
TargetLowering::ConstraintType
|
|
TargetLowering::getConstraintType(char ConstraintLetter) const {
|
|
// FIXME: lots more standard ones to handle.
|
|
switch (ConstraintLetter) {
|
|
default: return C_Unknown;
|
|
case 'r': return C_RegisterClass;
|
|
case 'm': // memory
|
|
case 'o': // offsetable
|
|
case 'V': // not offsetable
|
|
return C_Memory;
|
|
case 'i': // Simple Integer or Relocatable Constant
|
|
case 'n': // Simple Integer
|
|
case 's': // Relocatable Constant
|
|
case 'I': // Target registers.
|
|
case 'J':
|
|
case 'K':
|
|
case 'L':
|
|
case 'M':
|
|
case 'N':
|
|
case 'O':
|
|
case 'P':
|
|
return C_Other;
|
|
}
|
|
}
|
|
|
|
bool TargetLowering::isOperandValidForConstraint(SDOperand Op,
|
|
char ConstraintLetter) {
|
|
switch (ConstraintLetter) {
|
|
default: return false;
|
|
case 'i': // Simple Integer or Relocatable Constant
|
|
case 'n': // Simple Integer
|
|
case 's': // Relocatable Constant
|
|
return true; // FIXME: not right.
|
|
}
|
|
}
|
|
|
|
|
|
std::vector<unsigned> TargetLowering::
|
|
getRegClassForInlineAsmConstraint(const std::string &Constraint,
|
|
MVT::ValueType VT) const {
|
|
return std::vector<unsigned>();
|
|
}
|
|
|
|
|
|
std::pair<unsigned, const TargetRegisterClass*> TargetLowering::
|
|
getRegForInlineAsmConstraint(const std::string &Constraint,
|
|
MVT::ValueType VT) const {
|
|
if (Constraint[0] != '{')
|
|
return std::pair<unsigned, const TargetRegisterClass*>(0, 0);
|
|
assert(*(Constraint.end()-1) == '}' && "Not a brace enclosed constraint?");
|
|
|
|
// Remove the braces from around the name.
|
|
std::string RegName(Constraint.begin()+1, Constraint.end()-1);
|
|
|
|
// Figure out which register class contains this reg.
|
|
const MRegisterInfo *RI = TM.getRegisterInfo();
|
|
for (MRegisterInfo::regclass_iterator RCI = RI->regclass_begin(),
|
|
E = RI->regclass_end(); RCI != E; ++RCI) {
|
|
const TargetRegisterClass *RC = *RCI;
|
|
|
|
// If none of the the value types for this register class are valid, we
|
|
// can't use it. For example, 64-bit reg classes on 32-bit targets.
|
|
bool isLegal = false;
|
|
for (TargetRegisterClass::vt_iterator I = RC->vt_begin(), E = RC->vt_end();
|
|
I != E; ++I) {
|
|
if (isTypeLegal(*I)) {
|
|
isLegal = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (!isLegal) continue;
|
|
|
|
for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
|
|
I != E; ++I) {
|
|
if (StringsEqualNoCase(RegName, RI->get(*I).Name))
|
|
return std::make_pair(*I, RC);
|
|
}
|
|
}
|
|
|
|
return std::pair<unsigned, const TargetRegisterClass*>(0, 0);
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Loop Strength Reduction hooks
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// isLegalAddressImmediate - Return true if the integer value or
|
|
/// GlobalValue can be used as the offset of the target addressing mode.
|
|
bool TargetLowering::isLegalAddressImmediate(int64_t V) const {
|
|
return false;
|
|
}
|
|
bool TargetLowering::isLegalAddressImmediate(GlobalValue *GV) const {
|
|
return false;
|
|
}
|