Fix bug: BasicAA/2003-02-26-AccessSizeTest.ll
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5645 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index a4465eb..2242d4f 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -142,19 +142,44 @@
std::swap(V1Size, V2Size);
}
- if (const GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V1)) {
- AliasResult R = alias(GEP->getOperand(0), V1Size, V2, V2Size);
- if (R == NoAlias) return NoAlias;
- if (R == MustAlias) {
- // If there is at least one non-zero constant index, we know they cannot
- // alias.
- for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
- if (const Constant *C = dyn_cast<Constant>(GEP->getOperand(i)))
- if (!C->isNullValue())
+ if (V1Size != ~0U && V2Size != ~0U)
+ if (const GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V1)) {
+ AliasResult R = alias(GEP->getOperand(0), V1Size, V2, V2Size);
+ if (R == NoAlias) return NoAlias;
+ if (R == MustAlias) {
+ // If there is at least one non-zero constant index, we know they cannot
+ // alias.
+ bool ConstantFound = false;
+ for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
+ if (const Constant *C = dyn_cast<Constant>(GEP->getOperand(i)))
+ if (!C->isNullValue()) {
+ ConstantFound = true;
+ break;
+ }
+ if (ConstantFound) {
+ if (V2Size <= 1 && V1Size <= 1) // Just pointer check?
return NoAlias;
+
+ // Otherwise we have to check to see that the distance is more than
+ // the size of the argument... build an index vector that is equal to
+ // the arguments provided, except substitute 0's for any variable
+ // indexes we find...
+
+ std::vector<Value*> Indices;
+ Indices.reserve(GEP->getNumOperands()-1);
+ for (unsigned i = 1; i != GEP->getNumOperands(); ++i)
+ if (const Constant *C = dyn_cast<Constant>(GEP->getOperand(i)))
+ Indices.push_back((Value*)C);
+ else
+ Indices.push_back(Constant::getNullValue(Type::LongTy));
+ const Type *Ty = GEP->getOperand(0)->getType();
+ int Offset = getTargetData().getIndexedOffset(Ty, Indices);
+ if (Offset >= (int)V2Size || Offset <= -(int)V1Size)
+ return NoAlias;
+ }
+ }
}
- }
-
+
return MayAlias;
}