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Generalize SROA to allow the first index of a GEP to be non-zero. Add a

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missing check that an array reference doesn't go past the end of the array,
and remove some redundant checks for in-bound array and vector references
that are no longer needed.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91897 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bob Wilson
2009-12-22 06:57:14 +00:00
parent 665e947740
commit f27a4cd783
2 changed files with 57 additions and 23 deletions
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27
lib/Transforms/Scalar/ScalarReplAggregates.cpp
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@@ -464,13 +464,6 @@ void SROA::isSafeGEP(GetElementPtrInst *GEPI, AllocaInst *AI,
if (GEPIt == E)
return;
// The first GEP index must be zero.
if (!isa<ConstantInt>(GEPIt.getOperand()) ||
!cast<ConstantInt>(GEPIt.getOperand())->isZero())
return MarkUnsafe(Info);
if (++GEPIt == E)
return;
// Walk through the GEP type indices, checking the types that this indexes
// into.
for (; GEPIt != E; ++GEPIt) {
@@ -481,24 +474,10 @@ void SROA::isSafeGEP(GetElementPtrInst *GEPI, AllocaInst *AI,
ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPIt.getOperand());
if (!IdxVal)
return MarkUnsafe(Info);
if (const ArrayType *AT = dyn_cast<ArrayType>(*GEPIt)) {
// This GEP indexes an array. Verify that this is an in-range constant
// integer. Specifically, consider A[0][i]. We cannot know that the user
// isn't doing invalid things like allowing i to index an out-of-range
// subscript that accesses A[1]. Because of this, we have to reject SROA
// of any accesses into structs where any of the components are variables.
if (IdxVal->getZExtValue() >= AT->getNumElements())
return MarkUnsafe(Info);
} else {
const VectorType *VT = cast<VectorType>(*GEPIt);
if (IdxVal->getZExtValue() >= VT->getNumElements())
return MarkUnsafe(Info);
}
}
// All the indices are safe. Now compute the offset due to this GEP and
// check if the alloca has a component element at that offset.
// Compute the offset due to this GEP and check if the alloca has a
// component element at that offset.
SmallVector<Value*, 8> Indices(GEPI->op_begin() + 1, GEPI->op_end());
Offset += TD->getIndexedOffset(GEPI->getPointerOperandType(),
&Indices[0], Indices.size());
@@ -552,6 +531,8 @@ bool SROA::TypeHasComponent(const Type *T, uint64_t Offset, uint64_t Size) {
} else if (const ArrayType *AT = dyn_cast<ArrayType>(T)) {
EltTy = AT->getElementType();
EltSize = TD->getTypeAllocSize(EltTy);
if (Offset >= AT->getNumElements() * EltSize)
return false;
Offset %= EltSize;
} else {
return false;