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[X86] IsElementEquivalent - pull out exact matching for same index/op. #143367

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Merged
merged 2 commits into from
Jun 9, 2025
Merged

[X86] IsElementEquivalent - pull out exact matching for same index/op. #143367

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[X86] IsElementEquivalent - pull out exact matching for same index/op…
RKSimon Jun 9, 2025
33b76c3
Merge branch 'main' into x86-equivelt-exact
RKSimon Jun 9, 2025
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7 changes: 5 additions & 2 deletions llvm/lib/Target/X86/X86ISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9790,6 +9790,10 @@ static bool IsElementEquivalent(int MaskSize, SDValue Op, SDValue ExpectedOp,
(int)ExpectedVT.getVectorNumElements() != MaskSize)
return false;

// Exact match.
if (Idx == ExpectedIdx && Op == ExpectedOp)
return true;

switch (Op.getOpcode()) {
case ISD::BUILD_VECTOR:
// If the values are build vectors, we can look through them to find
Expand Down Expand Up @@ -9837,8 +9841,7 @@ static bool IsElementEquivalent(int MaskSize, SDValue Op, SDValue ExpectedOp,
SmallVector<int, 8> Mask;
DecodeVPERMMask(MaskSize, Op.getConstantOperandVal(1), Mask);
SDValue Src = Op.getOperand(0);
return (Mask[Idx] == Mask[ExpectedIdx]) ||
IsElementEquivalent(MaskSize, Src, Src, Mask[Idx],
return IsElementEquivalent(MaskSize, Src, Src, Mask[Idx],
Mask[ExpectedIdx]);
}
break;
Expand Down