[Bug target/113059] [14 regression] fftw fails tests for -O3 -m32 -march=znver2 since r14-6210-ge44ed92dbbe9d4

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113059

--- Comment #24 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:d413df070ba5efadd2fb8b6c6aa6003b8cae617b

commit r14-8797-gd413df070ba5efadd2fb8b6c6aa6003b8cae617b
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Mon Feb 5 09:33:26 2024 +0100

    i386: Clear REG_UNUSED and REG_DEAD notes from the IL at the end of
vzeroupper pass [PR113059]

    The move of the vzeroupper pass from after reload pass to after
    postreload_cse helped only partially, CSE-like passes can still invalidate
    those notes (especially REG_UNUSED) if they use some earlier register
    holding some value later on in the IL.

    So, either we could try to move it one pass further after gcse2 and hope
    no later pass invalidates the notes, or the following patch attempts to
    restore the REG_DEAD/REG_UNUSED state from GCC 13 and earlier, where
    the LRA or reload passes remove all REG_DEAD/REG_UNUSED notes and the notes
    reappear only at the start of dse2 pass when it calls
      df_note_add_problem ();
      df_analyze ();
    So, effectively
              NEXT_PASS (pass_postreload_cse);
              NEXT_PASS (pass_gcse2);
              NEXT_PASS (pass_split_after_reload);
              NEXT_PASS (pass_ree);
              NEXT_PASS (pass_compare_elim_after_reload);
              NEXT_PASS (pass_thread_prologue_and_epilogue);
    passes operate without those notes in the IL.
    While in GCC 14 mode switching computes the notes problem at the start of
    vzeroupper, the patch below removes them at the end of the pass again, so
    that the above passes continue to operate without them.

    2024-02-05  Jakub Jelinek  <jakub@redhat.com>

            PR target/113059
            * config/i386/i386-features.cc (rest_of_handle_insert_vzeroupper):
            Remove REG_DEAD/REG_UNUSED notes at the end of the pass before
            df_analyze call.