================ @@ -908,6 +908,73 @@ void CodeGenFunction::EmitIfStmt(const IfStmt &S) { incrementProfileCounter(&S); } +bool CodeGenFunction::checkIfLoopMustProgress(const Expr *ControllingExpression, + bool IsTrivialCXXLoop) { + if (CGM.getCodeGenOpts().getFiniteLoops() == + CodeGenOptions::FiniteLoopsKind::Always) + return true; + if (CGM.getCodeGenOpts().getFiniteLoops() == + CodeGenOptions::FiniteLoopsKind::Never) + return false; + + // Now apply rules for plain C (see 6.8.5.6 in C11). + // Loops with constant conditions do not have to make progress in any C + // version. + // As an extension, we consisider loops whose constant expression + // can be constant-folded. + Expr::EvalResult Result; + bool CondIsConstInt = + !ControllingExpression || + (ControllingExpression->EvaluateAsInt(Result, getContext()) && + Result.Val.isInt()); + bool IsTrue = CondIsConstInt && + (!ControllingExpression || Result.Val.getInt().getBoolValue()); + + if (getLangOpts().C99 && CondIsConstInt) + return false; + + // Loops with non-constant conditions must make progress in C11 and later. + if (getLangOpts().C11) + return true; + + // [C++26][intro.progress] (DR) + // The implementation may assume that any thread will eventually do one of the + // following: + // [...] + // - continue execution of a trivial infinite loop ([stmt.iter.general]). + if (getLangOpts().CPlusPlus11) { + if (IsTrivialCXXLoop && IsTrue) { + CurFn->removeFnAttr(llvm::Attribute::MustProgress); ---------------- efriedma-quic wrote:
This doesn't have the effect you want. Even if you remove mustprogress from the current function, we'll re-infer it if the caller is mustprogress. You have two options here, I think: - Introduce a call to llvm.sideeffect() (which dodges the whole issue because it counts as a "side-effect" for mustprogress). - Remove the mustprogress attribute from everything, and just mark individual loops with mustprogress metadata, like we do in C. https://github.com/llvm/llvm-project/pull/90066 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits