[Patch] Use __GCC_HAVE_SYNC_COMPARE_AND_SWAP_*

[Peter Dimov]

Paolo Carlini wrote:
> Peter Dimov wrote:
>
>> There is an alternative; supply the __sync_..._{1,2,4,8} functions
>> (as weak symbols maybe?) for i386 and similar targets, implemented
>> with a spinlock pool, as suggested in N2145. This will have the
>> advantage of making user code "just work". One downside would be
>> that some users may not realize that they're getting an emulation.
>
> I see. In fact, as you may remember, I have been asking for an
> infrastructure providing an emulation layer transparent to the users
> for *years*...

I understand, but isn't the infrastructure now almost in place? The compiler 
support is present; is it not just the library support that is missing?

> Now, mid of 2007, with x86_64 becoming more and more
> common and old Sparcs less and less common, I'm not sure the effort
> still makes sense...

I wish I could share your optimism. :-) Sadly, 386 is as rare as an 
architecture can be, and 486 is as common as possible, and yet we still have 
i386 as the default.