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make memdep use the getModRefInfo method for stores instead of the

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low-level alias() method, allowing it to reason more aggressively
about pointers into constant memory.  PR4189


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72403 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2009-05-25 21:28:56 +00:00
parent d67a1666ec
commit ab9cf1282b
2 changed files with 22 additions and 1 deletions
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10
lib/Analysis/MemoryDependenceAnalysis.cpp
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@ -202,9 +202,17 @@ getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad,
}
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
// If alias analysis can tell that this store is guaranteed to not modify
// the query pointer, ignore it. Use getModRefInfo to handle cases where
// the query pointer points to constant memory etc.
if (AA->getModRefInfo(SI, MemPtr, MemSize) == AliasAnalysis::NoModRef)
continue;
// Ok, this store might clobber the query pointer. Check to see if it is
// a must alias: in this case, we want to return this as a def.
Value *Pointer = SI->getPointerOperand();
uint64_t PointerSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
// If we found a pointer, check if it could be the same as our pointer.
AliasAnalysis::AliasResult R =
AA->alias(Pointer, PointerSize, MemPtr, MemSize);