[Bug tree-optimization/109011] missed optimization in presence of __builtin_ctz

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109011

--- Comment #21 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:705b0d2b62318b3935214f08a1cf023b1117acb8

commit r14-108-g705b0d2b62318b3935214f08a1cf023b1117acb8
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Apr 20 11:55:16 2023 +0200

    tree-vect-patterns: Pattern recognize ctz or ffs using clz, popcount or ctz
[PR109011]

    The following patch allows to vectorize __builtin_ffs*/.FFS even if
    we just have vector .CTZ support, or
__builtin_ffs*/.FFS/__builtin_ctz*/.CTZ
    if we just have vector .CLZ or .POPCOUNT support.
    It uses various expansions from Hacker's Delight book as well as GCC's
    expansion, in particular:
    .CTZ (X) = PREC - .CLZ ((X - 1) & ~X)
    .CTZ (X) = .POPCOUNT ((X - 1) & ~X)
    .CTZ (X) = (PREC - 1) - .CLZ (X & -X)
    .FFS (X) = PREC - .CLZ (X & -X)
    .CTZ (X) = PREC - .POPCOUNT (X | -X)
    .FFS (X) = (PREC + 1) - .POPCOUNT (X | -X)
    .FFS (X) = .CTZ (X) + 1
    where the first one can be only used if both CTZ and CLZ have value
    defined at zero (kind 2) and both have value of PREC there.
    If the original has value defined at zero and the latter doesn't
    for other forms or if it doesn't have matching value for that case,
    a COND_EXPR is added for that afterwards.

    The patch also modifies vect_recog_popcount_clz_ctz_ffs_pattern
    such that the two can work together.

    2023-04-20  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/109011
            * tree-vect-patterns.cc (vect_recog_ctz_ffs_pattern): New function.
            (vect_recog_popcount_clz_ctz_ffs_pattern): Move
vect_pattern_detected
            call later.  Don't punt for IFN_CTZ or IFN_FFS if it doesn't have
            direct optab support, but has instead IFN_CLZ, IFN_POPCOUNT or
            for IFN_FFS IFN_CTZ support, use vect_recog_ctz_ffs_pattern for
that
            case.
            (vect_vect_recog_func_ptrs): Add ctz_ffs entry.

            * gcc.dg/vect/pr109011-1.c: Remove -mpower9-vector from
            dg-additional-options.
            (baz, qux): Remove functions and corresponding dg-final.
            * gcc.dg/vect/pr109011-2.c: New test.
            * gcc.dg/vect/pr109011-3.c: New test.
            * gcc.dg/vect/pr109011-4.c: New test.
            * gcc.dg/vect/pr109011-5.c: New test.