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[TTI] Check type legalization of both src and result for fpto{u|s}i.sat. #147657

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Merged
merged 5 commits into from
Jul 10, 2025
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[TTI] Check type legalization of both src and result for fpto{u|s}i.sat. #147657

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9253fc6
Precommit test case.
ElvisWang123 Jun 11, 2025
6b8397d
[TTI] Check type legalization of both src and result for fpto{u|s}i.sat.
ElvisWang123 Jul 9, 2025
31815b2
fixup undef value.
ElvisWang123 Jul 9, 2025
0972f9c
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ElvisWang123 Jul 10, 2025
23990c0
Update llvm/include/llvm/CodeGen/BasicTTIImpl.h
ElvisWang123 Jul 10, 2025
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15 changes: 11 additions & 4 deletions llvm/include/llvm/CodeGen/BasicTTIImpl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2486,11 +2486,18 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
ISD = ISD::UMULO;
break;
case Intrinsic::fptosi_sat:
ISD = ISD::FP_TO_SINT_SAT;
break;
case Intrinsic::fptoui_sat:
ISD = ISD::FP_TO_UINT_SAT;
case Intrinsic::fptoui_sat: {
std::pair<InstructionCost, MVT> SrcLT = getTypeLegalizationCost(Tys[0]);
std::pair<InstructionCost, MVT> RetLT = getTypeLegalizationCost(RetTy);

// For cast instructions, types are differnt between source and
// destination. Also need to check if the source type can be legalize.
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I don't understand this, any type should be legalizable. Why would this ever return an invalid cost?

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Some of the vector type might not be legalize if the target not support.

For example, fptoui.sat(<vscale x 1 x double> ...) is illegal type under riscv64, +zve32f (target only support f32 vectors no f64 vector support) and cannot be scalarize since the element counts is unknown at compile time. So the cost of fptoui.sat(<vscale x 1 x double> ...) should be invalid.

if (!SrcLT.first.isValid() || !RetLT.first.isValid())
return InstructionCost::getInvalid();
ISD = IID == Intrinsic::fptosi_sat ? ISD::FP_TO_SINT_SAT
: ISD::FP_TO_UINT_SAT;
break;
}
case Intrinsic::ctpop:
ISD = ISD::CTPOP;
// In case of legalization use TCC_Expensive. This is cheaper than a
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