https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126404
--- Comment #9 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-16 branch has been updated by Richard Biener <[email protected]>: https://gcc.gnu.org/g:762b68f15e6442aca835f1bb6da5e483f4ad0c1c commit r16-9458-g762b68f15e6442aca835f1bb6da5e483f4ad0c1c Author: Richard Biener <[email protected]> Date: Tue Jul 28 14:21:15 2026 +0200 tree-optimization/126404 - CTZ pattern destroying reductions CTZ pattern recognition can recurse through a temporary pattern stmt but that will fail to be detected as part of a reduction because the setup is partial. This causes the reduction chain to break due to multiple uses. Avoid recursing in case the original pattern is for a reduction. PR tree-optimization/126404 * tree-vect-patterns.cc (vect_recog_popcount_clz_ctz_ffs_pattern): Avoid recursing to vect_recog_ctz_ffs_pattern with a reduction. * gcc.dg/vect/vect-pr126404.c: Adjust. (cherry picked from commit a97f2ef0d90d46144b39a8c9ea670b52dd13233a)
