[Bug tree-optimization/110903] [12/13 Regression] Dead Code Elimination Regression

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110903

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[12/13/14 Regression] Dead  |[12/13 Regression] Dead
                   |Code Elimination Regression |Code Elimination Regression

--- Comment #5 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #4)
> (In reply to Thomas Koenig from comment #3)
> > The code from comment#2 and from comment#3 no longer calls foo
> > with current trunk, r14-5108-g751fc7bcdcdf25 .
> > 
> > Now, to see which commit fixed it...
> 
> My bet is on r14-4089-gd45ddc2c04e471 .

Weird thing is that I do see this on POWER (I often use gcc120 for
compiling because it is the beefiest machine I can lay my hands on).

However, this was actually fixed by r14-4141-gbf6b107e2a3423:

bf6b107e2a342319b3787ec960fc8014ef3aff91 is the first new commit
commit bf6b107e2a342319b3787ec960fc8014ef3aff91
Author: Andrew MacLeod <amacleod@redhat.com>
Date:   Wed Sep 13 11:52:15 2023 -0400

    New early __builtin_unreachable processing.

    in VRP passes before __builtin_unreachable MUST be removed, only remove it
    if all exports affected by the unreachable can have global values updated,
and
    do not involve loads from memory.

            PR tree-optimization/110080
            PR tree-optimization/110249
            gcc/
            * tree-vrp.cc (remove_unreachable::final_p): New.
            (remove_unreachable::maybe_register): Rename from
            maybe_register_block and call early or final routine.
            (fully_replaceable): New.
            (remove_unreachable::handle_early): New.
            (remove_unreachable::remove_and_update_globals): Remove
            non-final processing.
            (rvrp_folder::rvrp_folder): Add final flag to constructor.
            (rvrp_folder::post_fold_bb): Remove unreachable registration.
            (rvrp_folder::pre_fold_stmt): Move unreachable processing to here.
            (execute_ranger_vrp): Adjust some call parameters.

            gcc/testsuite/
            * g++.dg/pr110249.C: New.
            * gcc.dg/pr110080.c: New.
            * gcc.dg/pr93917.c: Adjust.