[Bug lto/105600] New: ICE with LTO when building Mumble from git on arm64

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105600

            Bug ID: 105600
           Summary: ICE with LTO when building Mumble from git on arm64
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sam at gentoo dot org
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

Reported this downstream at https://bugs.gentoo.org/843974 initially.

Apologies for not being able to give more information yet. I'm familiar with
reducing "normal" ICEs but I'm getting stuck with how to get more info because
of LTO.

One issue is it seems like I can't find a way to keep all the temporary files
required.

The bug seems similar to bug 102067 (same stacktrace?).

ICE occurs when building Mumble from their git repo
(https://github.com/mumble-voip/mumble) at
4f50172c5c8bc7c425efb350377106d3e83a7e79.

Needs LTO.

Occurs on arm64 with GCC 11.3.0 and GCC 12.1.0.

I've reduced it down to:
```
$ /usr/bin/c++ -freport-bug -flto=99 -o /dev/null -O2 -fsanitize=undefined -O3
-DNDEBUG -Wl,-z,relro -Wl,-z,now
/root/mumble/build/src/tests/TestSettingsJSONSerialization/CMakeFiles/TestSettingsJSONSerialization.dir/TestSettingsJSONSerialization.cpp.o
/root/mumble/build/src/tests/TestSettingsJSONSerialization/../../mumble/CMakeFiles/mumble_client_object_lib.dir/JSONSerialization.cpp.o
during IPA pass: icf
lto1: internal compiler error: Segmentation fault
0xb13af3 crash_signal
        /usr/src/debug/sys-devel/gcc-12.1.0/gcc-12.1.0/gcc/toplev.cc:322
0xdc3e64 varpool_node::get_constructor()
        /usr/src/debug/sys-devel/gcc-12.1.0/gcc-12.1.0/gcc/varpool.cc:300
0x15b8f53 ipa_icf::sem_variable::equals(ipa_icf::sem_item*,
hash_map<symtab_node*, ipa_icf::sem_item*,
simple_hashmap_traits<default_hash_traits<symtab_node*>, ipa_icf::sem_item*>
>&)
        /usr/src/debug/sys-devel/gcc-12.1.0/gcc-12.1.0/gcc/ipa-icf.cc:1695
0x15b9f67 ipa_icf::sem_item_optimizer::subdivide_classes_by_equality(bool)
        /usr/src/debug/sys-devel/gcc-12.1.0/gcc-12.1.0/gcc/ipa-icf.cc:2732
0x15c0683 ipa_icf::sem_item_optimizer::execute()
        /usr/src/debug/sys-devel/gcc-12.1.0/gcc-12.1.0/gcc/ipa-icf.cc:2464
0x15c1d6f ipa_icf_driver
        /usr/src/debug/sys-devel/gcc-12.1.0/gcc-12.1.0/gcc/ipa-icf.cc:3600
0x15c1d6f ipa_icf::pass_ipa_icf::execute(function*)
        /usr/src/debug/sys-devel/gcc-12.1.0/gcc-12.1.0/gcc/ipa-icf.cc:3647
Please submit a full bug report, with preprocessed source.
Please include the complete backtrace with any bug report.
See <https://bugs.gentoo.org/> for instructions.
lto-wrapper: fatal error: /usr/bin/c++ returned 1 exit status
compilation terminated.
/usr/lib/gcc/aarch64-unknown-linux-gnu/12.1.0/../../../../aarch64-unknown-linux-gnu/bin/ld:
error: lto-wrapper failed
collect2: error: ld returned 1 exit status
```

What more information do you need? I can give access to the environment if
required. Cheers.