[Patch libstdc++] Rewrite cpu/generic/atomic_word.h

[Jonathan Wakely]

On 12/06/15 10:30 +0100, Ramana Radhakrishnan wrote:
>On Fri, Jun 12, 2015 at 10:06 AM, Jonathan Wakely <jwakely@redhat.com> wrote:
>> On 11/06/15 23:56 +0200, Torvald Riegel wrote:
>>>>
>>>> > On Fri, 2015-05-22 at 12:37 +0100, Ramana Radhakrishnan wrote:
>>>> I don't think we can remove _GLIBCXX_READ_MEM_BARRIER and
>>>> _GLIBCXX_WRITE_MEM_BARRIER from atomic_word.h even though they are
>>>> superseded by the atomics as it is published in the documentation as
>>>> available macros.
>>>
>>>
>>> I see.  We should at least update the documentation of those, as the
>>> current one isn't a really portable specification.  If we can, I'd
>>> deprecate them.  Jonathan, what do you think?
>>
>>
>> Yes, I'm in favour of deprecating them. They are GCC-specific anyway,
>> so there is no reason to prefer them to std::atomic_ or __atomic_
>> fences.
>
>I'll treat it as a follow-up.

Sure.

>Can I get an ack for this patch though ? I could backport this as is
>to fix the problems on ARM / AArch64 (PR target/66200) - alternatively
>I'll provide header implementations of the same for the release
>branches.

Yes, OK for trunk, thanks.

I think it's safer if the backport only changes the ARM and AArch64
implementations, at least for now. If no problems are found on trunk
we could consider backporting the whole thing for all targets, but it
may not be worth it if the other targets are working OK.