This is the mail archive of the
gcc-help@gcc.gnu.org
mailing list for the GCC project.
Re: __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16 not defined on aarch64
On 29/06/17 15:05, Toebs Douglass wrote:
> I wrote:
>> I may be utterly, utterly wrong, but I think what's happened makes
>> perfect sense at each step of the way but has led to an outcome which
>> is crazy. I publish a lock-free data structure library and I must
>> specifically avoid libatomic.
>
> Sorry to be so unconstructive, though. I don't know enough about GCC
> and libatomic to be able to meaningfully make other proposals; I can
> only write as an end user.
Well, yeah. We can only really blame ARM for this: they provided a
double-word CAS but no way to define a double-word atomic load which
does not also store. I hesitate to place blame on the ARM architects,
a splendid and diligent bunch, but there it is. I have no idea why
LDXP doesn't work as an atomic load, but it does not.
--
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671