https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105562
--- Comment #15 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:844a5c8ca768dc0cc90c1a943756610832d686a8 commit r12-8400-g844a5c8ca768dc0cc90c1a943756610832d686a8 Author: Richard Biener <rguent...@suse.de> Date: Thu May 12 12:13:29 2022 +0200 tree-optimization/105562 - avoid uninit diagnostic with better FRE We can avoid some uninit diagnostics by making FRE disambiguate against CLOBBERs since any aliasing there would invoke undefined behavior for a read we are looking up. 2022-05-12 Richard Biener <rguent...@suse.de> PR tree-optimization/105562 * tree-ssa-sccvn.cc (vn_reference_lookup_3): Disambiguate against all CLOBBER defs if there's not an obvious must-alias and we are not doing redundant store elimination. (vn_walk_cb_data::redundant_store_removal_p): New field. (vn_reference_lookup_pieces): Initialize it. (vn_reference_lookup): Add argument to specify if we are doing redundant store removal. (eliminate_dom_walker::eliminate_stmt): Specify we do. * tree-ssa-sccvn.h (vn_reference_lookup): Adjust. * g++.dg/warn/uninit-pr105562.C: New testcase. (cherry picked from commit 94b8a37fa16f7638cc1965718f4ec71719506743)
