[Bug tree-optimization/127149] Wrong code with vectorisation of popcount of bitint

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127149

--- Comment #6 from GCC 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:431068af077e13f0113f3640385b7b6cfa0a3e68

commit r17-3855-g431068af077e13f0113f3640385b7b6cfa0a3e68
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Sep 2 11:27:11 2026 +0200

    vect-patterns: Fix up vect_recog_popcount_clz_ctz_ffs_pattern for non-mode
precision types [PR127149]

    The following testcase is miscompiled on aarch64-linux.  The problem is
that
    vect_recog_popcount_clz_ctz_ffs_pattern for builtins other than clz
    doesn't require type_has_mode_precision_p (lhs_type) and matches to an ifn
    with an argument with say _BitInt(7) type (as well as result) and we then
    happily vectorize it and match something that doesn't properly extend the
    padding bits.

    One possibility is to punt in this case (i.e.
      if (!type_has_mode_precision_p (lhs_type))
        return NULL;
    ), the following patch instead pattern matches it with a cast to/from
    the TREE_TYPE (vec_type), i.e. the actual mode precision type we'll use
    for the vectorization.

    2026-09-02  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/127149
            * tree-vect-patterns.cc (vect_recog_popcount_clz_ctz_ffs_pattern):
            Handle lhs_type without mode precision by adding casts.

            * gcc.dg/bitint-142.c: New test.

    Reviewed-by: Richard Biener <rguenth@suse.de>