https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107087
--- Comment #5 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:2b9d76c1af189b918a9970f471e6d2e2c08f7e7d commit r13-6905-g2b9d76c1af189b918a9970f471e6d2e2c08f7e7d Author: Richard Biener <rguent...@suse.de> Date: Mon Mar 27 15:18:41 2023 +0200 tree-optimization/107087 - missed CCP after forwprop When forwprop simplifies the CFG the 2nd order opportunities by exposed degenerate PHIs are not realized. The following improves this by properly tracking executable edges and thus handling this for non-cyclic CFGs at least. This avoids the bogus diagnostic reported for the testcase in this PR. PR tree-optimization/107087 * tree-ssa-forwprop.cc (pass_forwprop::execute): Track executable regions to avoid useless work and to better propagate degenerate PHIs. * g++.dg/pr107087.C: New testcase.