[Bug tree-optimization/126404] [16 Regression] ICE at -O2/3 on aarch64 during GIMPLE pass: vect

"cvs-commit at gcc dot gnu.org via Gcc-bugs" <[email protected]> Tue, 28 Jul 2026 13:20:59 +0000

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126404

--- Comment #7 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:a97f2ef0d90d46144b39a8c9ea670b52dd13233a

commit r17-2750-ga97f2ef0d90d46144b39a8c9ea670b52dd13233a
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.