[LTP] [PATCH v3 1/3] tst_atomic: drop legacy inline assembly and use __atomic or __sync builtins

[Li Wang]

On Fri, Jun 6, 2025 at 10:39 PM Petr Vorel <pvorel@suse.cz> wrote:

> Hi Li, Cyril,
>
> > Refactor tst_atomic.h to remove all legacy architecture-specific inline
> > assembly and fallback code paths. The new implementation supports only
> > two well-defined interfaces: __atomic_* built-ins (GCC ≥ 4.7) and
> __sync_*
> > built-ins (GCC ≥ 4.1).
>
> > This simplification improves maintainability, clarity, and portability
> > across platforms.
>
> > The memory order is explicitly set to __ATOMIC_SEQ_CST to preserve strict
> > sequential consistency, which aligns with the C++11 memory model.
>
> > Reference:
> https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html
> +1
>
> Thanks for the work!
> Reviewed-by: Petr Vorel <pvorel@suse.cz>
>
> > Signed-off-by: Li Wang <liwang@redhat.com>
> > Suggested-by: Cyril Hrubis <chrubis@suse.cz>
>
> > +
> > +/* Use __atomic built-ins (GCC >= 4.7), with sequential consistency. */
>
> +1 for documenting this. Hopefully these are old enough to not having to
> mention
> it in the docs. But if you think it's not that old, it might be worth
> later to
> document it in doc/users/supported_systems.rst.
>
> https://linux-test-project.readthedocs.io/en/latest/users/supported_systems.html
>
> In that case minimal clang version should be noted as well.
>
> BTW I tried to search, should it be clang 3.5?
> I tried to search but not found.
> https://clang.llvm.org/docs/LanguageExtensions.html#c11-atomic-builtins



https://releases.llvm.org/3.1/docs/ReleaseNotes.html
>From the release notes, Clang was implemented __atomic builtins in v3.1.

And you made a good point, we also need to note the minimal Clang version,
Something like:

  /* Use __atomic built-ins (GCC >= 4.7, Clang >= 3.1), with sequential
consistency. */


P.s.

The worth to mention github CI also passed with remove __sync built-ins,
but to be on safe side, I still keep them in, maybe for someone's use on
older
platform.

https://github.com/wangli5665/ltp/commit/3b1b81e662c49b04b79c2bdf807d818984a2dbd9


-- 
Regards,
Li Wang