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TTI: Check legalization cost of mul overflow ISD nodes #100519

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Aug 8, 2024
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TTI: Check legalization cost of mul overflow ISD nodes #100519

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67 changes: 36 additions & 31 deletions llvm/include/llvm/CodeGen/BasicTTIImpl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2196,37 +2196,11 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
ISD = ISD::USUBO;
break;
case Intrinsic::smul_with_overflow:
case Intrinsic::umul_with_overflow: {
Type *MulTy = RetTy->getContainedType(0);
Type *OverflowTy = RetTy->getContainedType(1);
unsigned ExtSize = MulTy->getScalarSizeInBits() * 2;
Type *ExtTy = MulTy->getWithNewBitWidth(ExtSize);
bool IsSigned = IID == Intrinsic::smul_with_overflow;

unsigned ExtOp = IsSigned ? Instruction::SExt : Instruction::ZExt;
TTI::CastContextHint CCH = TTI::CastContextHint::None;

InstructionCost Cost = 0;
Cost += 2 * thisT()->getCastInstrCost(ExtOp, ExtTy, MulTy, CCH, CostKind);
Cost +=
thisT()->getArithmeticInstrCost(Instruction::Mul, ExtTy, CostKind);
Cost += 2 * thisT()->getCastInstrCost(Instruction::Trunc, MulTy, ExtTy,
CCH, CostKind);
Cost += thisT()->getArithmeticInstrCost(Instruction::LShr, ExtTy,
CostKind,
{TTI::OK_AnyValue, TTI::OP_None},
{TTI::OK_UniformConstantValue, TTI::OP_None});

if (IsSigned)
Cost += thisT()->getArithmeticInstrCost(Instruction::AShr, MulTy,
CostKind,
{TTI::OK_AnyValue, TTI::OP_None},
{TTI::OK_UniformConstantValue, TTI::OP_None});

Cost += thisT()->getCmpSelInstrCost(
BinaryOperator::ICmp, MulTy, OverflowTy, CmpInst::ICMP_NE, CostKind);
return Cost;
}
ISD = ISD::SMULO;
break;
case Intrinsic::umul_with_overflow:
ISD = ISD::UMULO;
break;
case Intrinsic::fptosi_sat:
case Intrinsic::fptoui_sat: {
if (Tys.empty())
Expand Down Expand Up @@ -2371,6 +2345,37 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
OverflowTy, Pred, CostKind);
return Cost;
}
case Intrinsic::smul_with_overflow:
case Intrinsic::umul_with_overflow: {
Type *MulTy = RetTy->getContainedType(0);
Type *OverflowTy = RetTy->getContainedType(1);
unsigned ExtSize = MulTy->getScalarSizeInBits() * 2;
Type *ExtTy = MulTy->getWithNewBitWidth(ExtSize);
bool IsSigned = IID == Intrinsic::smul_with_overflow;

unsigned ExtOp = IsSigned ? Instruction::SExt : Instruction::ZExt;
TTI::CastContextHint CCH = TTI::CastContextHint::None;

InstructionCost Cost = 0;
Cost += 2 * thisT()->getCastInstrCost(ExtOp, ExtTy, MulTy, CCH, CostKind);
Cost +=
thisT()->getArithmeticInstrCost(Instruction::Mul, ExtTy, CostKind);
Cost += 2 * thisT()->getCastInstrCost(Instruction::Trunc, MulTy, ExtTy,
CCH, CostKind);
Cost += thisT()->getArithmeticInstrCost(
Instruction::LShr, ExtTy, CostKind, {TTI::OK_AnyValue, TTI::OP_None},
{TTI::OK_UniformConstantValue, TTI::OP_None});

if (IsSigned)
Cost += thisT()->getArithmeticInstrCost(
Instruction::AShr, MulTy, CostKind,
{TTI::OK_AnyValue, TTI::OP_None},
{TTI::OK_UniformConstantValue, TTI::OP_None});

Cost += thisT()->getCmpSelInstrCost(
BinaryOperator::ICmp, MulTy, OverflowTy, CmpInst::ICMP_NE, CostKind);
return Cost;
}
case Intrinsic::sadd_sat:
case Intrinsic::ssub_sat: {
// Assume a default expansion.
Expand Down
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