[llvm-commits] [llvm] r110120 - /llvm/trunk/lib/Analysis/AliasAnalysis.cpp
Dan Gohman
gohman at apple.com
Tue Aug 3 10:27:43 PDT 2010
Author: djg
Date: Tue Aug 3 12:27:43 2010
New Revision: 110120
URL: http://llvm.org/viewvc/llvm-project?rev=110120&view=rev
Log:
Make AliasAnalysis::getModRefInfo conservative in the face of volatility.
Modified:
llvm/trunk/lib/Analysis/AliasAnalysis.cpp
Modified: llvm/trunk/lib/Analysis/AliasAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/AliasAnalysis.cpp?rev=110120&r1=110119&r2=110120&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/AliasAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/AliasAnalysis.cpp Tue Aug 3 12:27:43 2010
@@ -78,8 +78,17 @@
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 @@
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
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