Author: Jinsong Ji Date: 2026-07-08T09:23:39-04:00 New Revision: 44858419d766322d9c51d85f4ac83501a5181597
URL: https://github.com/llvm/llvm-project/commit/44858419d766322d9c51d85f4ac83501a5181597 DIFF: https://github.com/llvm/llvm-project/commit/44858419d766322d9c51d85f4ac83501a5181597.diff LOG: Revert "[clang][AST] Inline StmtVisitor fallback methods" for STMT macro in debug builds (#208106) This partially reverts commit 8b50847a31f927d258cf22953035db206d42fc5d. The LLVM_ATTRIBUTE_ALWAYS_INLINE on STMT macro fallback methods caused stack overflow in debug builds when processing deeply nested expressions. The test many-logical-ops.c with 2000+ logical AND operators would crash in SequenceChecker due to excessive stack consumption. Introduce LLVM_ATTRIBUTE_ALWAYS_INLINE_UNLESS_DEBUG which expands to LLVM_ATTRIBUTE_ALWAYS_INLINE in release builds (preserving the binary size optimization) but to plain `inline` in debug builds (avoiding stack overflow). Apply this to the STMT macro while keeping LLVM_ATTRIBUTE_ALWAYS_INLINE on BINOP_FALLBACK, CAO_FALLBACK, and UNARYOP_FALLBACK. Fixes regressions in debug builds only: Clang :: C/C99/n590.c Clang :: Index/index-many-logical-ops.c Clang :: Sema/deep_recursion.c Clang :: Sema/many-logical-ops.c Co-Authored-By: Claude Sonnet 4.5 <[email protected]> --------- Co-authored-by: Claude Sonnet 4.5 <[email protected]> Added: Modified: clang/include/clang/AST/StmtVisitor.h llvm/include/llvm/Support/Compiler.h Removed: ################################################################################ diff --git a/clang/include/clang/AST/StmtVisitor.h b/clang/include/clang/AST/StmtVisitor.h index 45e203578c9fd..e4b3d35a9b16e 100644 --- a/clang/include/clang/AST/StmtVisitor.h +++ b/clang/include/clang/AST/StmtVisitor.h @@ -115,8 +115,10 @@ class StmtVisitorBase { // If the implementation chooses not to implement a certain visit method, fall // back on VisitExpr or whatever else is the superclass. + // Note: In debug builds, avoid ALWAYS_INLINE to prevent stack overflow with + // deeply nested expressions (e.g., 2000+ logical operators). #define STMT(CLASS, PARENT) \ - LLVM_ATTRIBUTE_ALWAYS_INLINE \ + LLVM_ATTRIBUTE_ALWAYS_INLINE_UNLESS_DEBUG \ RetTy Visit##CLASS(PTR(CLASS) S, ParamTys... P) { DISPATCH(PARENT, PARENT); } #include "clang/AST/StmtNodes.inc" diff --git a/llvm/include/llvm/Support/Compiler.h b/llvm/include/llvm/Support/Compiler.h index 35f92b2b51430..cffab778deeb4 100644 --- a/llvm/include/llvm/Support/Compiler.h +++ b/llvm/include/llvm/Support/Compiler.h @@ -358,6 +358,15 @@ #define LLVM_ATTRIBUTE_ALWAYS_INLINE inline #endif +/// LLVM_ATTRIBUTE_ALWAYS_INLINE_UNLESS_DEBUG - Like +/// LLVM_ATTRIBUTE_ALWAYS_INLINE but disabled in debug builds to avoid stack +/// overflow with deep recursion. +#if defined(NDEBUG) +#define LLVM_ATTRIBUTE_ALWAYS_INLINE_UNLESS_DEBUG LLVM_ATTRIBUTE_ALWAYS_INLINE +#else +#define LLVM_ATTRIBUTE_ALWAYS_INLINE_UNLESS_DEBUG inline +#endif + /// LLVM_ATTRIBUTE_NO_DEBUG - On compilers where we have a directive to do /// so, mark a method "no debug" because debug info makes the debugger /// experience worse. _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
