https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104172
--- Comment #16 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-11 branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:79b0091b13eb7dce0294407d9bd78750df10180d commit r11-9510-g79b0091b13eb7dce0294407d9bd78750df10180d Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Jan 25 05:49:05 2022 +0100 rs6000: Remove GCC 8.1 U10__float128 mangling compatibility [PR104172] In GCC 7.x and earlier, while it had -mabi=ieeelongdouble option, that option was undocumented and unsupported. In GCC 8.1 that option got documented and -mabi=ieeelongdouble long double started to be mangled as U10__float128. In GCC 9 and backported to before 8.2 release, that mangling changed to u9__ieee128 and a support for emitting compatibility mangling aliases have been added. Unfortunately, as mentioned in the PR, those don't really work well in many cases, the free_lang_data pass throws away important trees, so e.g. with -flto -ffat-lto-objects the compiler often ICEs on templates that involve IEEE quad long double arguments etc. because the mangling was done too late (at final time). Furthermore, lto1's mangler is not the C++ mangler, so with -flto it would often emit as "mangled identifiers" something that wasn't a valid assembler identifier, e.g. operator+ etc. While it is possible to do such mangling earlier, e.g. at the same time when the C++ FE emits its mangling aliases and untested proof of concept is in the PR, there seems to be agreement that we shouldn't bother with this ABI compatibility with something that probably nobody really used. GCC 8.2 already uses the new mangling, it was just a few months, but more importantly, libstdc++ support for IEEE quad long double on powerpc64le-linux was only added in GCC 11, and glibc support for that some weeks after 8.2 got released. So, the following patch just drops those aliases. 2022-01-25 Jakub Jelinek <ja...@redhat.com> PR target/104172 gcc/ * config/rs6000/rs6000-internal.h (rs6000_passes_ieee128): Don't declare. * config/rs6000/rs6000.c (rs6000_passes_ieee128, ieee128_mangling_gcc_8_1): Remove. (TARGET_ASM_GLOBALIZE_DECL_NAME): Don't redefine. (rs6000_mangle_type): Return "u9__ieee128" instead of ieee128_mangling_gcc_8_1 ? "U10__float128" : "u9__ieee128". (rs6000_globalize_decl_name): Remove. * config/rs6000/rs6000-call.c (init_cumulative_args, rs6000_function_arg_advance_1): Don't set rs6000_passes_ieee128. (cherry picked from commit f4ee27d3262fc4fc3e5d3535f195fdcf87d7ec77)
