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Fix bug: BasicAA/2003-02-26-AccessSizeTest.ll

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5645 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-02-26 21:57:23 +00:00
parent 2271fddb6d
commit c330ee6f02
1 changed files with 36 additions and 11 deletions
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47
lib/Analysis/BasicAliasAnalysis.cpp
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@ -142,19 +142,44 @@ BasicAliasAnalysis::alias(const Value *V1, unsigned V1Size,
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;
}