atomic_cmpset_64 vs atomic_cas_64

[Mateusz Guzik]

On 10/4/19, Andriy Gapon <avg at freebsd.org> wrote:
>
> I see that almost all 64-bit platforms provide atomic_cmpset_64, but
> sparc64
> provides atomic_cas_64 (instead?).
> I think that the meanings of "cas" and "cmpset" are really the same, but I
> am
> not sure if there are any differences in that the functions do.
> Could anyone who knows that stuff (sparc64 assembly) please shed some
> light?
> Thanks!
>
> #define     atomic_cas_64(p, e, s)  casxa((p), (e), (s), __ASI_ATOMIC)
>

cas returns the found value, while cmpset throws it away.

static __inline int                                                     \
atomic_cmpset_ ## name(volatile ptype p, vtype e, vtype s)              \
{                                                                       \
        return (((vtype)atomic_cas((p), (e), (s), sz)) == (e));         \
}


Just use fcmpset instead.

-- 
Mateusz Guzik <mjguzik gmail.com>