On 3/06/2023 00:53, Gabriel Ravier wrote: > On 2/06/2023 14:59, Jakub Jelinek wrote: > >> Sure, some builtins are officially supported. >> Those are meant to be used directly by users. >> >> Then there are many builtins which are implementation detail for some >> other API that users should use instead. >> That includes e.g. builtins used under the hood for <*intrin.h> >> implementation - users should use the intrinsics from those headers, >> that is documented interface which is supported by multiple compilers, >> or builtins used under the hood inside of libstdc++ headers (again, >> users should use standard C++ APIs which are supported by multiple >> compilers instead of the builtins directly) etc. >> E.g. between GCC 3.4 and current trunk 62 __builtin_ia32_* builtins >> which were implementation details of the x86 intrinsic headers >> have been removed as the intrinsics got implemented some other way >> (e.g. using generic vectors etc.). > > Does it matter whether or not those builtins are documented ? It seems > like most of the __builtin_ia32_ builtins are explicitly documented in > the manual, despite the fact that these seem like those you're referring > to as being potentially removable at will whenever - and I see no > indication in the documentation that they are implementation details/may > be removed at any time for any reason. Hello Gabriel, As far as I understand, Jakub is merely saying: If a builtin is NOT documented, then it is NOT part of the API. https://gcc.gnu.org/onlinedocs/gcc.pdf *builtin_ia32_addcarry* appears nowhere in the manual, thus it is NOT documented, thus it is NOT part of the API. Regards
