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refactor the MemoryBuiltin analysis:

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- provide more extensive set of functions to detect library allocation functions (e.g., malloc, calloc, strdup, etc)
 - provide an API to compute the size and offset of an object pointed by

Move a few clients (GVN, AA, instcombine, ...) to the new API.
This implementation is a lot more aggressive than each of the custom implementations being replaced.

Patch reviewed by Nick Lewycky and Chandler Carruth, thanks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158919 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nuno Lopes
2012-06-21 15:45:28 +00:00
parent 2114a8aaba
commit 9e72a79ef4
11 changed files with 716 additions and 289 deletions
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lib/Analysis/BasicAliasAnalysis.cpp
+4 -41
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@@ -86,47 +86,10 @@ static bool isEscapeSource(const Value *V) {
/// UnknownSize if unknown.
static uint64_t getObjectSize(const Value *V, const TargetData &TD,
bool RoundToAlign = false) {
Type *AccessTy;
unsigned Align;
if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
if (!GV->hasDefinitiveInitializer())
return AliasAnalysis::UnknownSize;
AccessTy = GV->getType()->getElementType();
Align = GV->getAlignment();
} else if (const AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
if (!AI->isArrayAllocation())
AccessTy = AI->getType()->getElementType();
else
return AliasAnalysis::UnknownSize;
Align = AI->getAlignment();
} else if (const CallInst* CI = extractMallocCall(V)) {
if (!RoundToAlign && !isArrayMalloc(V, &TD))
// The size is the argument to the malloc call.
if (const ConstantInt* C = dyn_cast<ConstantInt>(CI->getArgOperand(0)))
return C->getZExtValue();
return AliasAnalysis::UnknownSize;
} else if (const Argument *A = dyn_cast<Argument>(V)) {
if (A->hasByValAttr()) {
AccessTy = cast<PointerType>(A->getType())->getElementType();
Align = A->getParamAlignment();
} else {
return AliasAnalysis::UnknownSize;
}
} else {
return AliasAnalysis::UnknownSize;
}
if (!AccessTy->isSized())
return AliasAnalysis::UnknownSize;
uint64_t Size = TD.getTypeAllocSize(AccessTy);
// If there is an explicitly specified alignment, and we need to
// take alignment into account, round up the size. (If the alignment
// is implicit, getTypeAllocSize is sufficient.)
if (RoundToAlign && Align)
Size = RoundUpToAlignment(Size, Align);
return Size;
uint64_t Size;
if (getObjectSize(V, Size, &TD, RoundToAlign))
return Size;
return AliasAnalysis::UnknownSize;
}
/// isObjectSmallerThan - Return true if we can prove that the object specified