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author | Dan Gohman <gohman@apple.com> | 2010-08-03 17:27:43 +0000 |
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committer | Dan Gohman <gohman@apple.com> | 2010-08-03 17:27:43 +0000 |
commit | 14a498a48677eb1eaddd8329330df073224f9575 (patch) | |
tree | 355cf241a06355f4c6bf338c224c88c0d262da11 | |
parent | bae696956b74680a7fedafb7fea70628d1ef14df (diff) | |
download | external_llvm-14a498a48677eb1eaddd8329330df073224f9575.zip external_llvm-14a498a48677eb1eaddd8329330df073224f9575.tar.gz external_llvm-14a498a48677eb1eaddd8329330df073224f9575.tar.bz2 |
Make AliasAnalysis::getModRefInfo conservative in the face of volatility.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110120 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/Analysis/AliasAnalysis.cpp | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/lib/Analysis/AliasAnalysis.cpp b/lib/Analysis/AliasAnalysis.cpp index 503fbbd..60ea2b4 100644 --- a/lib/Analysis/AliasAnalysis.cpp +++ b/lib/Analysis/AliasAnalysis.cpp @@ -78,8 +78,17 @@ AliasAnalysis::getModRefInfo(CallSite CS1, CallSite CS2) { AliasAnalysis::ModRefResult AliasAnalysis::getModRefInfo(LoadInst *L, Value *P, unsigned Size) { - return alias(L->getOperand(0), getTypeStoreSize(L->getType()), - P, Size) ? Ref : NoModRef; + // If the load address doesn't alias the given address, it doesn't read + // or write the specified memory. + if (!alias(L->getOperand(0), getTypeStoreSize(L->getType()), P, Size)) + return NoModRef; + + // Be conservative in the face of volatile. + if (L->isVolatile()) + return ModRef; + + // Otherwise, a load just reads. + return Ref; } AliasAnalysis::ModRefResult @@ -90,9 +99,17 @@ AliasAnalysis::getModRefInfo(StoreInst *S, Value *P, unsigned Size) { getTypeStoreSize(S->getOperand(0)->getType()), P, Size)) return NoModRef; + // Be conservative in the face of volatile. + if (S->isVolatile()) + return ModRef; + // If the pointer is a pointer to constant memory, then it could not have been // modified by this store. - return pointsToConstantMemory(P) ? NoModRef : Mod; + if (pointsToConstantMemory(P)) + return NoModRef; + + // Otherwise, a store just writes. + return Mod; } AliasAnalysis::ModRefBehavior |