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[VectorCombine] Fix invalid shuffle cost argument of foldShuffleOfSelects #130281

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Merged
merged 2 commits into from
Mar 7, 2025
Merged

[VectorCombine] Fix invalid shuffle cost argument of foldShuffleOfSelects #130281

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eb61e31
[VectorCombine] Fix invalid shuffle cost argument of foldShuffleOfSel…
ParkHanbum Mar 7, 2025
6027063
Fix invalid argument in getCmpSelInstrCost
ParkHanbum Mar 7, 2025
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21 changes: 11 additions & 10 deletions llvm/lib/Transforms/Vectorize/VectorCombine.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2037,7 +2037,6 @@ bool VectorCombine::foldShuffleOfSelects(Instruction &I) {
m_Mask(Mask))))
return false;

auto *DstVecTy = dyn_cast<FixedVectorType>(I.getType());
auto *C1VecTy = dyn_cast<FixedVectorType>(C1->getType());
auto *C2VecTy = dyn_cast<FixedVectorType>(C2->getType());
if (!C1VecTy || !C2VecTy || C1VecTy != C2VecTy)
Expand All @@ -2051,24 +2050,26 @@ bool VectorCombine::foldShuffleOfSelects(Instruction &I) {
(SI0FOp->getFastMathFlags() != SI1FOp->getFastMathFlags())))
return false;

auto *SrcVecTy = dyn_cast<FixedVectorType>(T1->getType());
auto *DstVecTy = dyn_cast<FixedVectorType>(I.getType());
auto SK = TargetTransformInfo::SK_PermuteTwoSrc;
auto SelOp = Instruction::Select;
InstructionCost OldCost = TTI.getCmpSelInstrCost(
SelOp, T1->getType(), C1VecTy, CmpInst::BAD_ICMP_PREDICATE, CostKind);
OldCost += TTI.getCmpSelInstrCost(SelOp, T2->getType(), C2VecTy,
SelOp, DstVecTy, C1VecTy, CmpInst::BAD_ICMP_PREDICATE, CostKind);
OldCost += TTI.getCmpSelInstrCost(SelOp, DstVecTy, C2VecTy,
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@RKSimon RKSimon Mar 7, 2025

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Should still be SrcVecTy for the getCmpSelInstrCost calls?

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@ParkHanbum ParkHanbum Mar 7, 2025 •
edited
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I see that SelectInst takes a DestVecTy as an argument,
I referenced it from VPlanRecipes.cpp:2192, LoopVectorize.cpp:3398, LoopVectorize.cpp-6581
am I wrong?

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@RKSimon RKSimon Mar 7, 2025

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DstVecTy in this case is the result of the shuffle, SrcVecTy is the result of the select

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@ParkHanbum ParkHanbum Mar 7, 2025

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ahhh..! you right!

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@ParkHanbum ParkHanbum Mar 7, 2025

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I've fixed the my stupid mistake, thank you.

CmpInst::BAD_ICMP_PREDICATE, CostKind);
OldCost += TTI.getShuffleCost(SK, DstVecTy, Mask, CostKind, 0, nullptr,
OldCost += TTI.getShuffleCost(SK, SrcVecTy, Mask, CostKind, 0, nullptr,
{I.getOperand(0), I.getOperand(1)}, &I);

auto *C1C2VecTy = cast<FixedVectorType>(
toVectorTy(Type::getInt1Ty(I.getContext()), DstVecTy->getNumElements()));
InstructionCost NewCost =
TTI.getShuffleCost(SK, C1C2VecTy, Mask, CostKind, 0, nullptr, {C1, C2});
TTI.getShuffleCost(SK, C1VecTy, Mask, CostKind, 0, nullptr, {C1, C2});
NewCost +=
TTI.getShuffleCost(SK, DstVecTy, Mask, CostKind, 0, nullptr, {T1, T2});
TTI.getShuffleCost(SK, SrcVecTy, Mask, CostKind, 0, nullptr, {T1, T2});
NewCost +=
TTI.getShuffleCost(SK, DstVecTy, Mask, CostKind, 0, nullptr, {F1, F2});
NewCost += TTI.getCmpSelInstrCost(SelOp, DstVecTy, DstVecTy,
TTI.getShuffleCost(SK, SrcVecTy, Mask, CostKind, 0, nullptr, {F1, F2});
auto *C1C2ShuffledVecTy = cast<FixedVectorType>(
toVectorTy(Type::getInt1Ty(I.getContext()), DstVecTy->getNumElements()));
NewCost += TTI.getCmpSelInstrCost(SelOp, DstVecTy, C1C2ShuffledVecTy,
CmpInst::BAD_ICMP_PREDICATE, CostKind);

LLVM_DEBUG(dbgs() << "Found a shuffle feeding two selects: " << I
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