https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114579
--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:bbe83599320288025a417c54d9afcb3885cb2766 commit r15-99-gbbe83599320288025a417c54d9afcb3885cb2766 Author: Richard Biener <rguent...@suse.de> Date: Thu Apr 4 14:00:10 2024 +0200 middle-end/114579 - speed up add_scope_conflicts The following speeds up stack variable conflict detection by recognizing that the all-to-all conflict recording is only necessary for CFG merges as it's the unioning of the live variable sets that doesn't come with explicit mentions we record conflicts for. If we employ this optimization we have to make sure to perform the all-to-all conflict recording for all CFG merges even those into empty blocks where we might previously have skipped this. I have reworded the comment before the all-to-all conflict recording since it seemed to be confusing and missing the point - but maybe I am also missing something here. Nevertheless for the testcase in the PR the compile-time spend in add_scope_conflicts at -O1 drops from previously 67s (39%) to 10s (9%). PR middle-end/114579 * cfgexpand.cc (add_scope_conflicts_1): Record all-to-all conflicts only when there's a CFG merge but for all CFG merges.
