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[MemCpyOptimizer] hasUndefContents - only look for underlying object if we've found an alloca

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Provides an early-out if we fail to find an AllocaInst, and avoids a static analyzer warning about null dereferencing.
This commit is contained in:
Simon Pilgrim 2022-01-06 15:14:53 +00:00
parent 8399fa673b
commit 5bbcff6181
1 changed files with 8 additions and 6 deletions
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14
llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
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@ -1271,12 +1271,14 @@ static bool hasUndefContents(MemorySSA *MSSA, AliasAnalysis *AA, Value *V,
// does) and we're querying a pointer based on that alloca, then we know
// the memory is definitely undef, regardless of how exactly we alias.
// The size also doesn't matter, as an out-of-bounds access would be UB.
auto *Alloca = dyn_cast<AllocaInst>(getUnderlyingObject(V));
if (getUnderlyingObject(II->getArgOperand(1)) == Alloca) {
const DataLayout &DL = Alloca->getModule()->getDataLayout();
if (Optional<TypeSize> AllocaSize = Alloca->getAllocationSizeInBits(DL))
if (*AllocaSize == LTSize->getValue() * 8)
return true;
if (auto *Alloca = dyn_cast<AllocaInst>(getUnderlyingObject(V))) {
if (getUnderlyingObject(II->getArgOperand(1)) == Alloca) {
const DataLayout &DL = Alloca->getModule()->getDataLayout();
if (Optional<TypeSize> AllocaSize =
Alloca->getAllocationSizeInBits(DL))
if (*AllocaSize == LTSize->getValue() * 8)
return true;
}
}
}
}