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Some minor comment changes in constant-folding comparisons. 

llvm-svn: 143391
This commit is contained in:
Eli Friedman 2011-10-31 22:54:30 +00:00
parent f1a7d2253a
commit 42fbd62d92
1 changed files with 6 additions and 2 deletions
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8
clang/lib/AST/ExprConstant.cpp
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@ -1983,12 +1983,13 @@ bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
return false;
// A constant address may compare equal to the address of a symbol.
// The one exception is that address of an object cannot compare equal
// to the null pointer.
// to a null pointer constant.
if ((!LHSValue.Base && !LHSValue.Offset.isZero()) ||
(!RHSValue.Base && !RHSValue.Offset.isZero()))
return false;
// It's implementation-defined whether distinct literals will have
// distinct addresses. We define it to be unspecified.
// distinct addresses. In clang, we do not guarantee the addresses are
// distinct.
if (IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue))
return false;
// We can't tell whether weak symbols will end up pointing to the same
@ -1996,6 +1997,9 @@ bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue))
return false;
// Pointers with different bases cannot represent the same object.
// (Note that clang defaults to -fmerge-all-constants, which can
// lead to inconsistent results for comparisons involving the address
// of a constant; this generally doesn't matter in practice.)
return Success(E->getOpcode() == BO_NE, E);
}