On Tue, Oct 4, 2022 at 10:13 AM Rich Felker <dalias@libc.org> wrote:

> If this is actually the case, it's disturbing that GCC does not seem
> to be getting it right either...
>

The __sync_* builtins are legacy and were never particularly well-defined
-- especially for non-x86 platforms. (Note that they don't include atomic
load/store operations, which are effectively unnecessary on x86, but vital
on most other architectures).

I would suggest that musl (and anyone else) really ought to migrate from
its homegrown atomics support to the standard C11 atomic memory model,
which _is_ well-defined and extensively studied. Such a migration will
certainly be a Project, of course...