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Simplify demanded bits of select sources where the condition is a constant vector

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160835 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Pete Cooper
2012-07-26 23:10:24 +00:00
parent 3ba90d9c0e
commit 7971de4178
3 changed files with 53 additions and 0 deletions
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11
lib/Transforms/InstCombine/InstCombineSelect.cpp
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@ -899,5 +899,16 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
return &SI;
}
if (VectorType* VecTy = dyn_cast<VectorType>(SI.getType())) {
unsigned VWidth = VecTy->getNumElements();
APInt UndefElts(VWidth, 0);
APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
if (Value *V = SimplifyDemandedVectorElts(&SI, AllOnesEltMask, UndefElts)) {
if (V != &SI)
return ReplaceInstUsesWith(SI, V);
return &SI;
}
}
return 0;
}