[Bug ada/98228] [11 Regression] ICE: Assert_Failure atree.adb:931: Error detected at s-gearop.adb:382:34 [a-ngrear.adb:313:7 [a-nllrar.ads:18:1]] on s390x-linux-gnu

[mhillen at linux dot ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98228

Marius Hillenbrand <mhillen at linux dot ibm.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mhillen at linux dot ibm.com

--- Comment #6 from Marius Hillenbrand <mhillen at linux dot ibm.com> ---
I reproduced and bisected with the config shared by Matthias. The issue begins
with the introduction of ipa-modref. There is an inbetween range of commits
that fail with a different symptom, yet this commit is the first I found that
exactly fails as initially reported here:

commit d119f34c952f8718fdbabc63e2f369a16e92fa07
Author: Jan Hubicka <jh@suse.cz>
Date:   Sun Sep 20 07:25:16 2020 +0200

    New modref/ipa_modref optimization passes

    2020-09-19  David Cepelik  <d@dcepelik.cz>
                Jan Hubicka  <hubicka@ucw.cz>

            * Makefile.in: Add ipa-modref.c and ipa-modref-tree.c.
            * alias.c: (reference_alias_ptr_type_1): Export.
            * alias.h (reference_alias_ptr_type_1): Declare.
            * common.opt (fipa-modref): New.
            * gengtype.c (open_base_files): Add ipa-modref-tree.h and
ipa-modref.h
            * ipa-modref-tree.c: New file.
            * ipa-modref-tree.h: New file.
            * ipa-modref.c: New file.
            * ipa-modref.h: New file.
            * lto-section-in.c (lto_section_name): Add ipa_modref.
            * lto-streamer.h (enum lto_section_type): Add
LTO_section_ipa_modref.
            * opts.c (default_options_table): Enable ipa-modref at -O1+.
            * params.opt (-param=modref-max-bases, -param=modref-max-refs,
            -param=modref-max-tests): New params.
            * passes.def: Schedule pass_modref and pass_ipa_modref.
            * timevar.def (TV_IPA_MODREF): New timevar.
            (TV_TREE_MODREF): New timevar.
            * tree-pass.h (make_pass_modref): Declare.
            (make_pass_ipa_modref): Declare.
            * tree-ssa-alias.c (dump_alias_stats): Include ipa-modref-tree.h
            and ipa-modref.h
            (alias_stats): Add modref_use_may_alias, modref_use_no_alias,
            modref_clobber_may_alias, modref_clobber_no_alias, modref_tests.
            (dump_alias_stats): Dump new stats.
            (nonoverlapping_array_refs_p): Fix formating.
            (modref_may_conflict): New function.
            (ref_maybe_used_by_call_p_1): Use it.
            (call_may_clobber_ref_p_1): Use it.
            (call_may_clobber_ref_p): Update.
            (stmt_may_clobber_ref_p_1): Update.
            * tree-ssa-alias.h (call_may_clobber_ref_p_1): Update.