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Subject: [Bug tree-optimization/103116] SLP vectoriser fails to peel for gaps
Date: Wed, 04 May 2022 13:12:42 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103116

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:52b7b86f8c72eb19e637f1e72ffd10f39b8cb829

commit r13-110-g52b7b86f8c72eb19e637f1e72ffd10f39b8cb829
Author: Richard Biener <rguenther@suse.de>
Date:   Wed May 4 10:43:07 2022 +0200

    tree-optimization/103116 - SLP permutes and peeling for gaps

    The testcase shows that we can end up with a contiguous access across
    loop iterations but by means of permutations the elements accessed
    might only cover parts of a vector.  In this case we end up with
    GROUP_GAP =3D=3D 0 but still need to avoid accessing excess elements
    in the last loop iterations.  Peeling for gaps is designed to cover
    this but a single scalar iteration might not cover all of the excess
    elements.  The following ensures peeling for gaps is done in this
    situation and when that isn't sufficient because we need to peel
    more than one iteration (gcc.dg/vect/pr103116-2.c), fail the SLP
    vectorization.

    2022-05-04  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/103116
            * tree-vect-stmts.cc (get_group_load_store_type): Handle the
            case we need peeling for gaps even though GROUP_GAP is zero.

            * gcc.dg/vect/pr103116-1.c: New testcase.
            * gcc.dg/vect/pr103116-2.c: Likewise.=