https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102498
--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-10 branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:0dcd7625b03a1bd5be927a4ade1ddf240587fc08 commit r10-10645-g0dcd7625b03a1bd5be927a4ade1ddf240587fc08 Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Sep 28 13:02:51 2021 +0200 i386: Don't emit fldpi etc. if -frounding-math [PR102498] i387 has instructions to store some transcedental numbers into the top of stack. The problem is that what exact bit in the last place one gets for those depends on the current rounding mode, the CPU knows the number with slightly higher precision. The compiler assumes rounding to nearest when comparing them against constants in the IL, but at runtime the rounding can be different and so some of these depending on rounding mode and the constant could be 1 ulp higher or smaller than expected. We only support changing the rounding mode at runtime if the non-default -frounding-mode option is used, so the following patch just disables using those constants if that flag is on. 2021-09-28 Jakub Jelinek <ja...@redhat.com> PR target/102498 * config/i386/i386.c (standard_80387_constant_p): Don't recognize special 80387 instruction XFmode constants if flag_rounding_math. * gcc.target/i386/pr102498.c: New test. (cherry picked from commit 3b7041e8345c2f1030e58620f28e22d64b2c196b)
