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Fix a miscompilation of 188.ammp with the new CFE. 188.ammp is accessing

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arrays out of range in a horrible way, but we shouldn't break it anyway.
Details in the comments.

llvm-svn: 26606
This commit is contained in:
Chris Lattner 2006-03-08 01:05:29 +00:00
parent 24aa564456
commit 256eff3ac6
1 changed files with 19 additions and 3 deletions
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22
lib/Transforms/Scalar/ScalarReplAggregates.cpp
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@ -289,7 +289,7 @@ int SROA::isSafeUseOfAllocation(Instruction *User) {
GetElementPtrInst *GEPI = cast<GetElementPtrInst>(User);
gep_type_iterator I = gep_type_begin(GEPI), E = gep_type_end(GEPI);
// The GEP is safe to transform if it is of the form GEP <ptr>, 0, <cst>
// The GEP is not safe to transform if not of the form "GEP <ptr>, 0, <cst>".
if (I == E ||
I.getOperand() != Constant::getNullValue(I.getOperand()->getType()))
return 0;
@ -308,13 +308,29 @@ int SROA::isSafeUseOfAllocation(Instruction *User) {
if (cast<ConstantInt>(GEPI->getOperand(2))->getRawValue() >= NumElements)
return 0;
// We cannot scalar repl this level of the array unless any array
// sub-indices are in-range constants. In particular, 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].
//
// Scalar replacing *just* the outer index of the array is probably not
// going to be a win anyway, so just give up.
for (++I; I != E && isa<ArrayType>(*I); ++I) {
const ArrayType *SubArrayTy = cast<ArrayType>(*I);
uint64_t NumElements = SubArrayTy->getNumElements();
if (!isa<ConstantInt>(I.getOperand())) return 0;
if (cast<ConstantInt>(I.getOperand())->getRawValue() >= NumElements)
return 0;
}
} else {
// If this is an array index and the index is not constant, we cannot
// promote... that is unless the array has exactly one or two elements in
// it, in which case we CAN promote it, but we have to canonicalize this
// out if this is the only problem.
if (NumElements == 1 || NumElements == 2)
return AllUsersAreLoads(GEPI) ? 1 : 0; // Canonicalization required!
if ((NumElements == 1 || NumElements == 2) &&
AllUsersAreLoads(GEPI))
return 1; // Canonicalization required!
return 0;
}
}