https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115823
--- Comment #1 from Gaius Mulley <gaius at gcc dot gnu.org> --- Created attachment 58626 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58626&action=edit Proposed fix Thanks for the bug report, confirmed and here is a proposed patch. The bug fix changes gcc/m2/gm2-gcc/m2builtins.c:m2builtins_BuiltinExists to recognise both __builtin_<functionname> and functionname as a builtin.