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Fix bug where array malloc with unexpected computation of the size argument resulted in MallocHelper

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identifying the malloc as a non-array malloc.  This broke GlobalOpt's optimization of stores of mallocs 
to global variables.

The fix is to classify malloc's into 3 categories:
1. non-array mallocs
2. array mallocs whose array size can be determined
3. mallocs that cannot be determined to be of type 1 or 2 and cannot be optimized

getMallocArraySize() returns NULL for category 3, and all users of this function must avoid their 
malloc optimization if this function returns NULL.

Eventually, currently unexpected codegen for computing the malloc's size argument will be supported in
isArrayMalloc() and getMallocArraySize(), extending malloc optimizations to those examples.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84199 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Victor Hernandez
2009-10-15 20:14:52 +00:00
parent 5814fefc7f
commit 2491ce0353
4 changed files with 72 additions and 37 deletions
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lib/Analysis/PointerTracking.cpp
+3 -2
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@@ -102,8 +102,9 @@ const SCEV *PointerTracking::computeAllocationCount(Value *P,
if (CallInst *CI = extractMallocCall(V)) {
Value *arraySize = getMallocArraySize(CI, P->getContext(), TD);
Ty = getMallocAllocatedType(CI);
if (!Ty || !arraySize) return SE->getCouldNotCompute();
const Type* AllocTy = getMallocAllocatedType(CI);
if (!AllocTy || !arraySize) return SE->getCouldNotCompute();
Ty = AllocTy;
// arraySize elements of type Ty.
return SE->getSCEV(arraySize);
}