[Bug tree-optimization/126466] [17 Regression] popcount recognition doesn't validate one of the masks since r17-489

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D126466

--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Venkataramanan Kumar
<[email protected]>:

https://gcc.gnu.org/g:7decbb57670c3c0f6136be00456fe9c8a41f7aed

commit r17-2897-g7decbb57670c3c0f6136be00456fe9c8a41f7aed
Author: Reshma Roy <[email protected]>
Date:   Thu Jul 30 12:19:08 2026 +0530

    match: Fix incorrect identification of POPCOUNT pattern [PR126466]

    This fixes r17-489-g8ca1e887847e2f, which added a third 32-bit
    Hacker's Delight popcount matcher.  Its predicate checked
    compare_tree_int (@5, 0x0F0F0F0F) twice and never validated the
    final outer AND constant (@7), so any mask was accepted once the
    earlier constants matched.

    Require compare_tree_int (@7, 0x0000003F) so only the intended
    popcount idiom is folded to IFN_POPCOUNT.

    gcc/ChangeLog:

            PR tree-optimization/126466
            * match.pd: Fix incorrect POPCOUNT identification in the third
            32-bit Hacker's Delight matcher.

    gcc/testsuite/ChangeLog:

            * gcc.dg/tree-ssa/popcount10.c: New test.=