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Stop using memdep for a check that didn't really make sense with memdep. In terms of specific issues, using memdep here checks irrelevant instructions and won't work properly once we start returning "unknown" more aggressively from memdep.

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llvm-svn: 133035
This commit is contained in:
Eli Friedman 2011-06-15 01:25:56 +00:00
parent 7624839811
commit a45cbb1743
1 changed files with 9 additions and 11 deletions
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20
lib/Transforms/Scalar/MemCpyOptimizer.cpp
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@ -487,7 +487,8 @@ bool MemCpyOpt::processStore(StoreInst *SI, BasicBlock::iterator &BBI) {
// happen to be using a load-store pair to implement it, rather than
// a memcpy.
if (LoadInst *LI = dyn_cast<LoadInst>(SI->getOperand(0))) {
if (!LI->isVolatile() && LI->hasOneUse()) {
if (!LI->isVolatile() && LI->hasOneUse() &&
LI->getParent() == SI->getParent()) {
MemDepResult ldep = MD->getDependency(LI);
CallInst *C = 0;
if (ldep.isClobber() && !isa<MemCpyInst>(ldep.getInst()))
@ -496,17 +497,14 @@ bool MemCpyOpt::processStore(StoreInst *SI, BasicBlock::iterator &BBI) {
if (C) {
// Check that nothing touches the dest of the "copy" between
// the call and the store.
MemDepResult sdep = MD->getDependency(SI);
if (!sdep.isNonLocal() && !sdep.isUnknown()) {
bool FoundCall = false;
for (BasicBlock::iterator I = SI, E = sdep.getInst(); I != E; --I) {
if (&*I == C) {
FoundCall = true;
break;
}
}
if (!FoundCall)
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
AliasAnalysis::Location StoreLoc = AA.getLocation(SI);
for (BasicBlock::iterator I = --BasicBlock::iterator(SI),
E = C; I != E; --I) {
if (AA.getModRefInfo(&*I, StoreLoc) != AliasAnalysis::NoModRef) {
C = 0;
break;
}
}
}