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[instcombine] Delete dead transform for reverse of binop #143967

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Merged
merged 3 commits into from
Jun 16, 2025
Merged

[instcombine] Delete dead transform for reverse of binop #143967

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95d8a50
[instcombine] Delete dead transform for rev(binop splat, rev(x))
preames Jun 12, 2025
fe299ec
Merge branch 'main' into pr-instcombine-reverse-dead-code
preames Jun 16, 2025
f605b39
Remove entire binop case
preames Jun 16, 2025
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29 changes: 5 additions & 24 deletions llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3555,32 +3555,13 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
break;
}
case Intrinsic::vector_reverse: {
Value *BO0, *BO1, *X, *Y;
Value *Vec = II->getArgOperand(0);
if (match(Vec, m_OneUse(m_BinOp(m_Value(BO0), m_Value(BO1))))) {
auto *OldBinOp = cast<BinaryOperator>(Vec);
if (match(BO0, m_VecReverse(m_Value(X)))) {
// rev(binop rev(X), rev(Y)) --> binop X, Y
if (match(BO1, m_VecReverse(m_Value(Y))))
return replaceInstUsesWith(CI, BinaryOperator::CreateWithCopiedFlags(
OldBinOp->getOpcode(), X, Y,
OldBinOp, OldBinOp->getName(),
II->getIterator()));
// rev(binop rev(X), BO1Splat) --> binop X, BO1Splat
if (isSplatValue(BO1))
return replaceInstUsesWith(CI, BinaryOperator::CreateWithCopiedFlags(
OldBinOp->getOpcode(), X, BO1,
OldBinOp, OldBinOp->getName(),
II->getIterator()));
}
// rev(binop BO0Splat, rev(Y)) --> binop BO0Splat, Y
if (match(BO1, m_VecReverse(m_Value(Y))) && isSplatValue(BO0))
return replaceInstUsesWith(CI,
BinaryOperator::CreateWithCopiedFlags(
OldBinOp->getOpcode(), BO0, Y, OldBinOp,
OldBinOp->getName(), II->getIterator()));
}
// Note: We canonicalize reverse after binops, so we don't need a
// corresponding binop case here. TODO: Consider canonicalizing
// reverse after fneg?

// rev(unop rev(X)) --> unop X
Value *X;
if (match(Vec, m_OneUse(m_UnOp(m_VecReverse(m_Value(X)))))) {
auto *OldUnOp = cast<UnaryOperator>(Vec);
auto *NewUnOp = UnaryOperator::CreateWithCopiedFlags(
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