port-sparc/58352: ld: /usr/lib/libubsan.so: undefined reference to `__sync_val_compare_and_swap_8'

[campbell+netbsd%mumble.net@localhost]

>Number:         58352
>Category:       port-sparc
>Synopsis:       ld: /usr/lib/libubsan.so: undefined reference to `__sync_val_compare_and_swap_8'
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-sparc-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jun 18 13:10:00 +0000 2024
>Originator:     Taylor R Campbell
>Release:        current
>Organization:
The NetBSD __sync_Foundation_8
>Environment:
NetBSD 10.99.10 (GENERIC) #0: Sun Jun 16 08:35:47 UTC 2024 root%babylon5.netbsd.org@localhost:/tmp/build/2024.06.16.00.12.33-sparc/obj/sys/arch/sparc/compile/GENERIC
>Description:
Since the gcc12 update, ubsan tests are failing with undefined references to __sync_val_compare_and_swap_8 -- presumably they previously didn't try to use 64-bit atomics and now they do, and sparc doesn't have 64-bit atomics (may affect other ports without 64-bit atomics too):

ld: /usr/lib/libubsan.so: undefined reference to `__sync_val_compare_and_swap_8'
Fail: regexp signed integer overflow not in stderr
execvp(./test) failed: No such file or directory

https://releng.netbsd.org/b5reports/sparc/2024/2024.06.16.00.12.33/test.html#usr.bin_c++_t_ubsan_int_add_overflow_int_add_overflow
>How-To-Repeat:
cd /usr/tests/usr.bin/c++
atf-run t_ubsan_int_add_overflow
>Fix:
Yes, please!