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[InstCombineVectorOps] Use poison instead of undef as placeholder [NFC]

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Undef was being used to populate unused vector lanes.
While at it, switch extractelement to use poison as the OOB value (per LangRef)
This commit is contained in:
Nuno Lopes
2023-07-20 08:14:43 +01:00
parent d76d5c7d89
commit 9324e1be07
1 changed files with 4 additions and 4 deletions
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8
llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
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@@ -546,7 +546,7 @@ Instruction *InstCombinerImpl::visitExtractElementInst(ExtractElementInst &EI) {
->getNumElements();
if (SrcIdx < 0)
return replaceInstUsesWith(EI, UndefValue::get(EI.getType()));
return replaceInstUsesWith(EI, PoisonValue::get(EI.getType()));
if (SrcIdx < (int)LHSWidth)
Src = SVI->getOperand(0);
else {
@@ -1480,10 +1480,10 @@ static Instruction *foldConstantInsEltIntoShuffle(InsertElementInst &InsElt) {
}
++ValI;
}
// Remaining values are filled with 'undef' values.
// Remaining values are filled with 'poison' values.
for (unsigned I = 0; I < NumElts; ++I) {
if (!Values[I]) {
Values[I] = UndefValue::get(InsElt.getType()->getElementType());
Values[I] = PoisonValue::get(InsElt.getType()->getElementType());
Mask[I] = I;
}
}
@@ -1704,7 +1704,7 @@ Instruction *InstCombinerImpl::visitInsertElementInst(InsertElementInst &IE) {
if (LR.first != &IE && LR.second != &IE) {
// We now have a shuffle of LHS, RHS, Mask.
if (LR.second == nullptr)
LR.second = UndefValue::get(LR.first->getType());
LR.second = PoisonValue::get(LR.first->getType());
return new ShuffleVectorInst(LR.first, LR.second, Mask);
}
}