https://gcc.gnu.org/bugzilla/show_bug.cgi?id=128209
--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <[email protected]>: https://gcc.gnu.org/g:def63f7c26207e4dfefcf5e92c07ea2582474dc5 commit r17-5658-gdef63f7c26207e4dfefcf5e92c07ea2582474dc5 Author: Richard Biener <[email protected]> Date: Tue Oct 27 17:02:58 2026 +0100 tree-optimization/128209 - fix uninitialized read of bb_to_rpo The following fixes the uninitialized read of bb_to_rpo introduced by the PR123298 fix. The issue is that nothing prevents walk_non_aliased_vuses to walk outside of the region and thus the backedge queries go where we do not have the information. To fix this we're marking the region with a local BB flag and conservatively treat out-of-region edges as backedges (apart from the entry edge which is known forward). PR tree-optimization/128209 * tree-ssa-sccvn.cc (vn_bb_in_region_flag, vn_entry_edge): New globals. (vn_is_backedge): Treat out-of-region edges conservatively. (do_rpo_vn_1): Split out region marking from verification-only to be always done.
