[Bug target/111784] [14 Regression] aarch64: ldp_stp_{15,16,17,18}.c test failures since r14-4579

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111784

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Kewen Lin <linkw@gcc.gnu.org>:

https://gcc.gnu.org/g:1908775f7982bd2de36df5d94396eca0865bad9a

commit r14-4842-g1908775f7982bd2de36df5d94396eca0865bad9a
Author: Kewen Lin <linkw@linux.ibm.com>
Date:   Sun Oct 22 21:18:40 2023 -0500

    vect: Cost adjacent vector loads/stores together [PR111784]

    As comments[1][2], this patch is to change the costing way
    on some adjacent vector loads/stores from costing one by
    one to costing them together with the total number once.

    It helps to fix the exposed regression PR111784 on aarch64,
    as aarch64 specific costing could make different decisions
    according to the different costing ways (counting with total
    number vs. counting one by one).  Based on a reduced test
    case from PR111784, only considering vec_num can fix the
    regression already, but vector loads/stores in regard to
    ncopies are also adjacent accesses, so they are considered
    as well.

    btw, this patch leaves the costing on dr_explicit_realign
    and dr_explicit_realign_optimized alone to make it simple.
    The costing way change can cause the differences for them
    since there is one costing depending on targetm.vectorize.
    builtin_mask_for_load and it's costed according to the
    calling times.  IIUC, these two dr_alignment_support are
    mainly used for old Power? (only having 16 bytes aligned
    vector load/store but no unaligned vector load/store).

    [1] https://gcc.gnu.org/pipermail/gcc-patches/2023-September/630742.html
    [2] https://gcc.gnu.org/pipermail/gcc-patches/2023-September/630744.html

            PR tree-optimization/111784

    gcc/ChangeLog:

            * tree-vect-stmts.cc (vectorizable_store): Adjust costing way for
            adjacent vector stores, by costing them with the total number
            rather than costing them one by one.
            (vectorizable_load): Adjust costing way for adjacent vector
            loads, by costing them with the total number rather than costing
            them one by one.