https://github.com/mugiwaraluffy56 created https://github.com/llvm/llvm-project/pull/178936
## Summary - Fix crash when passing non primitive types (structs) to `__builtin_infer_alloc_token` - The bytecode interpreter's discard loop dereferenced an empty `OptPrimType` for non primitive arguments ## Test plan - Added regression test in `clang/test/SemaCXX/alloc-token.cpp` - Existing tests continue to pass Fixes #178892 >From e35c3452f39c19855ede8937bd1bbd115e1e71d9 Mon Sep 17 00:00:00 2001 From: mugiwaraluffy56 <[email protected]> Date: Fri, 30 Jan 2026 23:59:32 +0530 Subject: [PATCH] [clang][bytecode] Fix crash on __builtin_infer_alloc_token with non-primitive arguments The discard loop assumed all arguments would have primitive types, but struct/class arguments are passed as pointers on the stack. Check if the type is classifiable before discarding. Fixes #178892 --- clang/lib/AST/ByteCode/InterpBuiltin.cpp | 8 ++++++-- clang/test/SemaCXX/alloc-token.cpp | 5 +++++ 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp index fb7c51608f85b..3e783953d3e64 100644 --- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp +++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp @@ -1398,8 +1398,12 @@ static bool interp__builtin_infer_alloc_token(InterpState &S, CodePtr OpPC, MaxTokensOpt.value_or(0) ? *MaxTokensOpt : (~0ULL >> (64 - BitWidth)); // We do not read any of the arguments; discard them. - for (int I = Call->getNumArgs() - 1; I >= 0; --I) - discard(S.Stk, *S.getContext().classify(Call->getArg(I))); + for (int I = Call->getNumArgs() - 1; I >= 0; --I) { + if (std::optional<PrimType> T = S.getContext().classify(Call->getArg(I))) + discard(S.Stk, *T); + else + S.Stk.discard<Pointer>(); // Non-primitive types are passed as pointers. + } // Note: Type inference from a surrounding cast is not supported in // constexpr evaluation. diff --git a/clang/test/SemaCXX/alloc-token.cpp b/clang/test/SemaCXX/alloc-token.cpp index 2a11e3366d5fb..aae25720d4329 100644 --- a/clang/test/SemaCXX/alloc-token.cpp +++ b/clang/test/SemaCXX/alloc-token.cpp @@ -79,4 +79,9 @@ void negative_tests() { negative_template_test<void>(); // expected-note {{in instantiation of function template specialization 'negative_template_test<void>' requested here}} constexpr auto inference_fail = __builtin_infer_alloc_token(123); // expected-error {{must be initialized by a constant expression}} \ // expected-note {{could not infer allocation type for __builtin_infer_alloc_token}} + + // PR178892: Ensure struct arguments don't crash the bytecode interpreter. + struct S {}; + constexpr auto struct_arg = __builtin_infer_alloc_token(S()); // expected-error {{must be initialized by a constant expression}} \ + // expected-note {{could not infer allocation type for __builtin_infer_alloc_token}} } _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
