[Bug ipa/91836] [10 Regression] Speed regression of 525.x264_r with -Ofast -march=native since r275982

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91836

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's likely been one of the vectorizer changes and fixed by

2019-09-20  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/91821
        * tree-vect-loop.c (check_reduction_path): Check we can compute
        reduc_idx.
        (vect_is_simple_reduction): Set STMT_VINFO_REDUC_IDX.
        * tree-vect-patterns.c (vect_reassociating_reduction_p): Return
        operands in canonical order.
        * tree-vectorizer.c (vec_info::new_stmt_vec_info): Initialize
        STMT_VINFO_REDUC_IDX.
        * tree-vectorizer.h (_stmt_vec_info::reduc_idx): New.
        (STMT_VINFO_REDUC_IDX): Likewise.