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constant fold extractelement with undef operands.

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llvm-svn: 27301
This commit is contained in:
Chris Lattner 2006-03-31 18:31:40 +00:00
parent 0af2e8be73
commit 8e584affdb
1 changed files with 7 additions and 1 deletions
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8
lib/VMCore/ConstantFolding.cpp
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@ -726,11 +726,17 @@ Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
const Constant *Idx) {
if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
return UndefValue::get(cast<PackedType>(Val->getType())->getElementType());
if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
if (const ConstantUInt *CIdx = dyn_cast<ConstantUInt>(Idx)) {
return const_cast<Constant*>(CVal->getOperand(CIdx->getValue()));
} else if (isa<UndefValue>(Idx)) {
// ee({w,x,y,z}, undef) -> w (an arbitrary value).
return const_cast<Constant*>(CVal->getOperand(0));
}
}
}
return 0;
}