diff options
author | Eli Friedman <eli.friedman@gmail.com> | 2012-04-16 19:23:57 +0000 |
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committer | Eli Friedman <eli.friedman@gmail.com> | 2012-04-16 19:23:57 +0000 |
commit | 2850376184b7e7aa81b5034ba44b001f8c55e07a (patch) | |
tree | c51e1f08f3dae46bbacd00330c6a909a035513bd /lib/AST/ExprConstant.cpp | |
parent | e9836a27cf93a58305ff3cf6d75ddc399c7d8ebf (diff) |
Per Richard's comments on r154794, add the checks necessary to handle constant-folding relational comparisons safely in case the user is using -fwrapv or equivalent.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@154849 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/AST/ExprConstant.cpp')
-rw-r--r-- | lib/AST/ExprConstant.cpp | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp index 4839c29976..66a88b065c 100644 --- a/lib/AST/ExprConstant.cpp +++ b/lib/AST/ExprConstant.cpp @@ -5090,8 +5090,6 @@ bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { // The comparison here must be unsigned, and performed with the same // width as the pointer. - // FIXME: Knowing the base is the same for the LHS and RHS isn't enough - // for relational operators. unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy); uint64_t CompareLHS = LHSOffset.getQuantity(); uint64_t CompareRHS = RHSOffset.getQuantity(); @@ -5100,6 +5098,19 @@ bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { CompareLHS &= Mask; CompareRHS &= Mask; + // If there is a base and this is a relational operator, we can only + // compare pointers within the object in question; otherwise, the result + // depends on where the object is located in memory. + if (!LHSValue.Base.isNull() && E->isRelationalOp()) { + QualType BaseTy = getType(LHSValue.Base); + if (BaseTy->isIncompleteType()) + return Error(E); + CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy); + uint64_t OffsetLimit = Size.getQuantity(); + if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit) + return Error(E); + } + switch (E->getOpcode()) { default: llvm_unreachable("missing comparison operator"); case BO_LT: return Success(CompareLHS < CompareRHS, E); |