Changes in directory llvm/lib/Transforms/Scalar:
ScalarReplAggregates.cpp updated: 1.36 -> 1.37
---
Log message:
Fix a miscompilation of 188.ammp with the new CFE. 188.ammp is accessing
arrays out of range in a horrible way, but we shouldn't break it anyway.
Details in the comments.
---
Diffs of the changes: (+19 -3)
ScalarReplAggregates.cpp | 22 +++++++++++++++++++---
1 files changed, 19 insertions(+), 3 deletions(-)
Index: llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp
diff -u llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp:1.36
llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp:1.37
--- llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp:1.36 Tue Jan 24
13:36:27 2006
+++ llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp Tue Mar 7 19:05:29 2006
@@ -289,7 +289,7 @@
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 @@
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;
}
}
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