https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86270
--- Comment #18 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:94d01a884702934bc03ccedff62e2c65515c8c83 commit r15-7637-g94d01a884702934bc03ccedff62e2c65515c8c83 Author: Richard Biener <rguent...@suse.de> Date: Wed Feb 12 11:20:10 2025 +0100 tree-optimization/86270 - improve SSA coalescing for loop exit test The PR indicates a very specific issue with regard to SSA coalescing failures because there's a pre IV increment loop exit test. While IVOPTs created the desired IL we later simplify the exit test into the undesirable form again. The following fixes this up during RTL expansion where we try to improve coalescing of IVs. That seems easier that trying to avoid the simplification with some weird heuristics (it could also have been written this way). PR tree-optimization/86270 * tree-outof-ssa.cc (insert_backedge_copies): Pattern match a single conflict in a loop condition and adjust that avoiding the conflict if possible. * gcc.target/i386/pr86270.c: Adjust to check for no reg-reg copies as well.
