[Bug tree-optimization/54346] combine permutations

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54346

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

https://gcc.gnu.org/g:fa553ff26d96f6fecaa8f1b00649cfdc6cda5f5a

commit r13-3430-gfa553ff26d96f6fecaa8f1b00649cfdc6cda5f5a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Oct 21 09:16:44 2022 +0200

    match.pd: Fix up gcc.dg/pr54346.c on i686-linux [PR54346]

    The pr54346.c testcase FAILs on i686-linux (without -msse*) for multiple
    reasons.  One is the trivial missing -Wno-psabi which the following patch
    adds, but that isn't enough.  The thing is that without native vector
    support, we have VEC_PERM_EXPRs in the IL and are actually considering
    the nested VEC_PERM_EXPRs into one VEC_PERM_EXPR optimization, but punt
    because can_vec_perm_const_p (result_mode, op_mode, sel2, false) is false.

    Such a test makes sense to prevent "optimizing" two VEC_PERM_EXPRs
    that can be handled by the backend natively into one VEC_PERM_EXPR
    that can't be handled.  But if both of the original VEC_PERM_EXPRs
    can't be handled natively either, having just one VEC_PERM_EXPR that will
be
    lowered by generic vec lowering is IMHO still better than 2.
    Or even if we trade just one VEC_PERM_EXPR that can't be handled plus
    one that can to one that can't be handled.

    Also, removing the testcase's executable permissions...

    2022-10-21  <jakub@redhat.com>

            PR tree-optimization/54346
            * match.pd ((vec_perm (vec_perm@0 @1 @2 VECTOR_CST) @0
VECTOR_CST)):
            Optimize nested VEC_PERM_EXPRs even if target can't handle the
            new one provided we don't increase number of VEC_PERM_EXPRs the
            target can't handle.

            * gcc.dg/pr54346.c: Add -Wno-psabi to dg-options.