https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112963
--- Comment #14 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:fdce86c9f07eb4f95ba438491c2b151e94be7ef2 commit r14-6451-gfdce86c9f07eb4f95ba438491c2b151e94be7ef2 Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Dec 12 08:57:02 2023 +0100 libquadmath: Restore linking against -lm on most targets [PR112963] The r14-4825 change added AC_CHECK_LIBM to libquadmath configure.ac and replaced unconditional linking with -lm with linking with $(LIBM) determined by that. Unfortunately that broke bare metal targets because AC_CHECK_LIBM attempts to link against -lm and this was after (unconditional) GCC_NO_EXECUTABLES. Then r14-4863 partially reverted that change (no longer AC_CHECK_LIBM), but didn't revert the Makefile.am change of -lm to $(LIBM), which had the effect that libquadmath is not linked against -lm on any arch. That is a serious problem though e.g. on Linux, because libquadmath calls a few libm entrypoints and e.g. on powerpc64le the underlinking can cause crashes in IFUNC resolvers of libm. Instead of adding further reversion of the r14-4825 commit and use -lm unconditionally again, this patch adds an AC_CHECK_LIBM like substitutions with the *-ncr-sysv4.3* target handling removed (I think we don't support such targets, especially not in libquadmath) and with the default case replaced by simple using -lm. That is something in between using -lm unconditionally and what AC_CHECK_LIBM does if it would work on bare metal - we know from GCC 13 and earlier that we can link -lm on all targets libquadmath is built for, and just white list a couple of targets which we know don't have separate -lm and don't want to link against that (like Darwin, Cygwin, ...). 2023-12-12 Jakub Jelinek <ja...@redhat.com> PR libquadmath/112963 * configure.ac (LIBM): Readd AC_CHECK_LIBM-like check without doing AC_CHECK_LIB in it. * configure: Regenerated. * Makefile.in: Regenerated.
