https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94589
--- Comment #22 from CVS 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:65061ea287a80cfb214e402cfd2373a14bfec95a commit r12-864-g65061ea287a80cfb214e402cfd2373a14bfec95a Author: Jakub Jelinek <ja...@redhat.com> Date: Tue May 18 10:08:51 2021 +0200 phiopt: Optimize partial_ordering spaceship >= 0 -ffinite-math-only [PR94589] As mentioned earlier, spaceship_replacement didn't optimize partial_ordering >= 0 comparisons, because the possible values are -1, 0, 1, 2 and the >= comparison is implemented as (res & 1) == res to choose the 0 and 1 cases from that. As we optimize that only with -ffinite-math-only, the 2 case is assumed not to happen and my earlier match.pd change optimizes (res & 1) == res into (res & ~1) == 0, so this patch pattern matches that case and handles it like res >= 0. 2021-05-18 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/94589 * tree-ssa-phiopt.c (spaceship_replacement): Pattern match phi result used in (res & ~1) == 0 comparison as res >= 0 as res == 2 would be UB with -ffinite-math-only. * g++.dg/opt/pr94589-2.C: Adjust scan-tree-dump count from 14 to 12.
