Author: jyknight Date: Tue Oct 9 19:53:43 2018 New Revision: 344110 URL: http://llvm.org/viewvc/llvm-project?rev=344110&view=rev Log: ExprConstant: Make __builtin_object_size use EM_IgnoreSideEffects.
And, since EM_OffsetFold is now unused, remove it. While builtin_object_size intends to ignore the presence of side-effects in its argument, the EM_OffsetFold mode was NOT configured to ignore side-effects. Rather it was effectively identical to EM_ConstantFold -- its explanatory comment notwithstanding. However, currently, keepEvaluatingAfterSideEffect() is not always honored -- sometimes evaluation continues despite it returning false. Therefore, since the b_o_s code was only checking the return value from evaluation, and not additionally checking the HasSideEffects flag, side-effects _were_ in many cases actually being ignored. This change is a prerequisite cleanup towards fixing that issue. Differential Revision: https://reviews.llvm.org/D52924 Modified: cfe/trunk/lib/AST/ExprConstant.cpp Modified: cfe/trunk/lib/AST/ExprConstant.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=344110&r1=344109&r2=344110&view=diff ============================================================================== --- cfe/trunk/lib/AST/ExprConstant.cpp (original) +++ cfe/trunk/lib/AST/ExprConstant.cpp Tue Oct 9 19:53:43 2018 @@ -759,18 +759,6 @@ namespace { /// context we try to fold them immediately since the optimizer never /// gets a chance to look at it. EM_PotentialConstantExpressionUnevaluated, - - /// Evaluate as a constant expression. In certain scenarios, if: - /// - we find a MemberExpr with a base that can't be evaluated, or - /// - we find a variable initialized with a call to a function that has - /// the alloc_size attribute on it - /// then we may consider evaluation to have succeeded. - /// - /// In either case, the LValue returned shall have an invalid base; in the - /// former, the base will be the invalid MemberExpr, in the latter, the - /// base will be either the alloc_size CallExpr or a CastExpr wrapping - /// said CallExpr. - EM_OffsetFold, } EvalMode; /// Are we checking whether the expression is a potential constant @@ -874,7 +862,6 @@ namespace { case EM_PotentialConstantExpression: case EM_ConstantExpressionUnevaluated: case EM_PotentialConstantExpressionUnevaluated: - case EM_OffsetFold: HasActiveDiagnostic = false; return OptionalDiagnostic(); } @@ -966,7 +953,6 @@ namespace { case EM_ConstantExpression: case EM_ConstantExpressionUnevaluated: case EM_ConstantFold: - case EM_OffsetFold: return false; } llvm_unreachable("Missed EvalMode case"); @@ -985,7 +971,6 @@ namespace { case EM_EvaluateForOverflow: case EM_IgnoreSideEffects: case EM_ConstantFold: - case EM_OffsetFold: return true; case EM_PotentialConstantExpression: @@ -1021,7 +1006,6 @@ namespace { case EM_ConstantExpressionUnevaluated: case EM_ConstantFold: case EM_IgnoreSideEffects: - case EM_OffsetFold: return false; } llvm_unreachable("Missed EvalMode case"); @@ -1093,18 +1077,18 @@ namespace { } }; - /// RAII object used to treat the current evaluation as the correct pointer - /// offset fold for the current EvalMode - struct FoldOffsetRAII { + /// RAII object used to set the current evaluation mode to ignore + /// side-effects. + struct IgnoreSideEffectsRAII { EvalInfo &Info; EvalInfo::EvaluationMode OldMode; - explicit FoldOffsetRAII(EvalInfo &Info) + explicit IgnoreSideEffectsRAII(EvalInfo &Info) : Info(Info), OldMode(Info.EvalMode) { if (!Info.checkingPotentialConstantExpression()) - Info.EvalMode = EvalInfo::EM_OffsetFold; + Info.EvalMode = EvalInfo::EM_IgnoreSideEffects; } - ~FoldOffsetRAII() { Info.EvalMode = OldMode; } + ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; } }; /// RAII object used to optionally suppress diagnostics and side-effects from @@ -8049,7 +8033,7 @@ static bool tryEvaluateBuiltinObjectSize // If there are any, but we can determine the pointed-to object anyway, then // ignore the side-effects. SpeculativeEvaluationRAII SpeculativeEval(Info); - FoldOffsetRAII Fold(Info); + IgnoreSideEffectsRAII Fold(Info); if (E->isGLValue()) { // It's possible for us to be given GLValues if we're called via @@ -8117,7 +8101,6 @@ bool IntExprEvaluator::VisitBuiltinCallE case EvalInfo::EM_ConstantFold: case EvalInfo::EM_EvaluateForOverflow: case EvalInfo::EM_IgnoreSideEffects: - case EvalInfo::EM_OffsetFold: // Leave it to IR generation. return Error(E); case EvalInfo::EM_ConstantExpressionUnevaluated: _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits