https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112281
--- Comment #7 from CVS 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:5ea2965b499f9e491e45db19fedbccfccb75076a commit r14-5444-g5ea2965b499f9e491e45db19fedbccfccb75076a Author: Richard Biener <rguent...@suse.de> Date: Tue Nov 14 11:37:13 2023 +0100 tree-optimization/112281 - loop distribution and zero dependence distances We currently distribute for (c = 2; c; c--) for (e = 0; e < 2; e++) { d[c] = b = d[c + 1]; d[c + 1].a = 0; } in a wrong way where the inner loop zero dependence distance should make us preserve stmt execution order. We fail to do so since we only look for a fully zero distance vector rather than looking at the innermost loop distance. This is somewhat similar to PR87022 where we instead looked at the outermost loop distance and changed this to what we do now. The following switches us to look at the innermost loop distance. PR tree-optimization/112281 * tree-loop-distribution.cc (pg_add_dependence_edges): Preserve stmt order when the innermost loop has exact overlap. * gcc.dg/torture/pr112281.c: New testcase.
