https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106922
--- Comment #23 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-12 branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:e364e27b6636ba09755790358910f199d07194b3 commit r12-8820-ge364e27b6636ba09755790358910f199d07194b3 Author: Richard Biener <rguent...@suse.de> Date: Thu Sep 15 13:33:23 2022 +0200 tree-optimization/106922 - PRE and virtual operand translation PRE implicitely keeps virtual operands at the blocks incoming version but the explicit updating point during PHI translation fails to trigger when there are no PHIs at all in a block. Later lazy updating then fails because of a too lose block check. A similar issues plagues reference invalidation when checking the ANTIC_OUT to ANTIC_IN translation. The following fixes both and makes the lazy updating work. The diagnostic testcase unfortunately requires boost so the testcase is the one I reduced for a missed optimization in PRE. The testcase fails with -m32 on x86_64 because we optimize too much before PRE which causes PRE to not trigger so we fail to eliminate a full redundancy. I'm going to open a separate bug for this. Hopefully the !lp64 selector is good enough. PR tree-optimization/106922 * tree-ssa-pre.cc (translate_vuse_through_block): Only keep the VUSE if its def dominates PHIBLOCK. (prune_clobbered_mems): Rewrite logic so we check whether a value dies in a block when the VUSE def doesn't dominate it. * g++.dg/tree-ssa/pr106922.C: New testcase. (cherry picked from commit 5edf02ed2b6de024f83a023d046a6a18f645bc83)
