[Bug target/97513] [11 regression] aarch64 SVE regressions since r11-3822

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97513

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Sandiford <rsandifo@gcc.gnu.org>:

https://gcc.gnu.org/g:2f3d9104610cb2058cf091707a20c1c6eff8d470

commit r11-8030-g2f3d9104610cb2058cf091707a20c1c6eff8d470
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Wed Apr 7 15:21:56 2021 +0100

    vect: Restore variable-length SLP permutes [PR97513]

    Many of the gcc.target/sve/slp-perm*.c tests started failing
    after the introduction of separate SLP permute nodes.
    This patch adds variable-length support using a similar
    technique to vect_transform_slp_perm_load.

    As there, the idea is to detect when every permute mask vector
    is the same and can be generated using a regular stepped sequence.
    We can easily handle those cases for variable-length, but still
    need to restrict the general case to constant-length.

    Again copying vect_transform_slp_perm_load, the idea is to distinguish
    the two cases regardless of whether the length is variable or not,
    partly to increase testing coverage and partly because it avoids
    generating redundant trees.

    Doing this means that we can also use SLP for the two-vector
    permute in pr88834.c, which we couldn't before VEC_PERM_EXPR
    nodes were introduced.  The patch therefore makes pr88834.c
    check that we don't regress back to not using SLP and adds
    pr88834_ld3.c to check for the original problem in the PR.

    gcc/
            PR tree-optimization/97513
            * tree-vect-slp.c (vect_add_slp_permutation): New function,
            split out from...
            (vectorizable_slp_permutation): ...here.  Detect cases in which
            all VEC_PERM_EXPRs are guaranteed to have the same stepped
            permute vector and only generate one permute vector for that case.
            Extend that case to handle variable-length vectors.

    gcc/testsuite/
            * gcc.target/aarch64/sve/pr88834.c: Expect the vectorizer to use
SLP.
            * gcc.target/aarch64/sve/pr88834_ld3.c: New test.