[Bug tree-optimization/123417] [16 Regression] missing sink vs GCC 15

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123417

--- Comment #8 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Andrew Pinski <pinskia@gcc.gnu.org>:

https://gcc.gnu.org/g:3ebe697f32197ec4a429fbf8dd9cce3155c0c9ba

commit r16-6679-g3ebe697f32197ec4a429fbf8dd9cce3155c0c9ba
Author: Andrew Pinski <andrew.pinski@oss.qualcomm.com>
Date:   Fri Jan 9 02:02:01 2026 -0800

    cfgcleanup: Protect latches always [PR123417]

    So it turns out LOOPS_MAY_HAVE_MULTIPLE_LATCHES is set in places
    along compiling. Setting it only means there might be multiple
    latches currently. It does not mean let's go in an delete them
    all; which is what remove_forwarder_block does currently. This
    was happening before my set of patches too but since it was
    only happening in merge_phi pass, latches were not cleared away
    al of the time and then recreated.

    This solves the problem by protecting latches all of the time
    instead of depedent on LOOPS_MAY_HAVE_MULTIPLE_LATCHES not being set.

    vect-uncounted_7.c needs to be xfailed here because we no longer
    vectorize the code. Note the IR between GCC 15 and after this patch
    is the same so I think this was just a case were the testcase
    was added after the remove forwarder changes and should not have
    vectorized (or vectorize differently).

    Bootstrapped and tested on x86_64-linux-gnu.

            PR tree-optimization/123417
    gcc/ChangeLog:

            * tree-cfgcleanup.cc (maybe_remove_forwarder_block): Always
            protect latches.

    gcc/testsuite/ChangeLog:

            * gcc.dg/vect/vect-uncounted_7.c: xfail vect test.

    Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>