[Bug ipa/111157] [14 Regression] 416.gamess fails with a run-time abort when compiled with -O2 -flto after r14-3226-gd073e2d75d9ed4

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111157

--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Martin Jambor <jamborm@gcc.gnu.org>:

https://gcc.gnu.org/g:997c8219f020091d00fd225c81270aa551bfe9e4

commit r14-5017-g997c8219f020091d00fd225c81270aa551bfe9e4
Author: Martin Jambor <mjambor@suse.cz>
Date:   Mon Oct 30 18:34:59 2023 +0100

    ipa: Prune any IPA-CP aggregate constants known by modref to be killed
(111157)

    PR 111157 shows that IPA-modref and IPA-CP (when plugged into value
    numbering) can optimize out a store both before a call (because the
    call will overwrite it) and in the call (because the store is of the
    same value) and by eliminating both create miscompilation.

    This patch fixes that by pruning any constants from the list of IPA-CP
    aggregate value constants that it knows the contents of the memory can
    be "killed."  Unfortunately, doing so is tricky.  First, IPA-modref
    loads override kills and so only stores not loaded are truly not
    necessary.  Looking stuff up there means doing what most of what
    modref_may_alias may do but doing exactly what it does is tricky
    because it takes also aliasing into account and has bail-out counters.

    To err on the side of caution in order to avoid this miscompilation we
    have to prune a constant when in doubt.  However, pruning can
    interfere with the mechanism of how clone materialization
    distinguishes between the cases when a parameter was entirely removed
    and when it was both IPA-CPed and IPA-SRAed (in order to make up for
    the removal in debug info, which can bump into an assert when
    compiling g++.dg/torture/pr103669.C when we are not careful).

    Therefore this patch:

      1) marks constants that IPA-modref has in its kill list with a new
         "killed" flag, and
      2) prunes the list from entries with this flag after materialization
         and IPA-CP transformation is done using the template introduced in
         the previous patch

    It does not try to look up anything in the load lists, this will be
    done as a follow-up in order to ease review.

    gcc/ChangeLog:

    2023-10-27  Martin Jambor  <mjambor@suse.cz>

            PR ipa/111157
            * ipa-prop.h (struct ipa_argagg_value): Newf flag killed.
            * ipa-modref.cc (ipcp_argagg_and_kill_overlap_p): New function.
            (update_signature): Mark any any IPA-CP aggregate constants at
            positions known to be killed as killed.  Move check that there is
            clone_info after this pruning.
            * ipa-cp.cc (ipa_argagg_value_list::dump): Dump the killed flag.
            (ipa_argagg_value_list::push_adjusted_values): Clear the new flag.
            (push_agg_values_from_plats): Likewise.
            (ipa_push_agg_values_from_jfunc): Likewise.
            (estimate_local_effects): Likewise.
            (push_agg_values_for_index_from_edge): Likewise.
            * ipa-prop.cc (write_ipcp_transformation_info): Stream the killed
            flag.
            (read_ipcp_transformation_info): Likewise.
            (ipcp_get_aggregate_const): Update comment, assert that encountered
            record does not have killed flag set.
            (ipcp_transform_function): Prune all aggregate constants with
killed
            set.

    gcc/testsuite/ChangeLog:

    2023-09-18  Martin Jambor  <mjambor@suse.cz>

            PR ipa/111157
            * gcc.dg/lto/pr111157_0.c: New test.
            * gcc.dg/lto/pr111157_1.c: Second file of the same new test.