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[MemCpyOpt] Look at any dependency -not just source- for memset+memcpy.

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This fixes another miscompile introduced by r235232: when there was a
dependency on the memcpy destination other than the memset, we would
ignore it, because we only looked at the source dependency.

It was a mistake to use SrcDepInfo.  Instead, just use DepInfo.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237066 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ahmed Bougacha
2015-05-11 23:09:46 +00:00
parent 12a7fbc55c
commit 6eb095d7ae
2 changed files with 25 additions and 6 deletions
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13
lib/Transforms/Scalar/MemCpyOptimizer.cpp
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@ -927,14 +927,12 @@ bool MemCpyOpt::processMemCpy(MemCpyInst *M) {
return true;
}
AliasAnalysis::Location SrcLoc = AliasAnalysis::getLocationForSource(M);
MemDepResult SrcDepInfo = MD->getPointerDependencyFrom(SrcLoc, true,
M, M->getParent());
MemDepResult DepInfo = MD->getDependency(M);
// Try to turn a partially redundant memset + memcpy into
// memcpy + smaller memset. We don't need the memcpy size for this.
if (SrcDepInfo.isClobber())
if (MemSetInst *MDep = dyn_cast<MemSetInst>(SrcDepInfo.getInst()))
if (DepInfo.isClobber())
if (MemSetInst *MDep = dyn_cast<MemSetInst>(DepInfo.getInst()))
if (processMemSetMemCpyDependence(M, MDep))
return true;
@ -948,7 +946,6 @@ bool MemCpyOpt::processMemCpy(MemCpyInst *M) {
// c) memcpy from freshly alloca'd space or space that has just started its
// lifetime copies undefined data, and we can therefore eliminate the
// memcpy in favor of the data that was already at the destination.
MemDepResult DepInfo = MD->getDependency(M);
if (DepInfo.isClobber()) {
if (CallInst *C = dyn_cast<CallInst>(DepInfo.getInst())) {
if (performCallSlotOptzn(M, M->getDest(), M->getSource(),
@ -961,6 +958,10 @@ bool MemCpyOpt::processMemCpy(MemCpyInst *M) {
}
}
AliasAnalysis::Location SrcLoc = AliasAnalysis::getLocationForSource(M);
MemDepResult SrcDepInfo = MD->getPointerDependencyFrom(SrcLoc, true,
M, M->getParent());
if (SrcDepInfo.isClobber()) {
if (MemCpyInst *MDep = dyn_cast<MemCpyInst>(SrcDepInfo.getInst()))
return processMemCpyMemCpyDependence(M, MDep, CopySize->getZExtValue());