[PATCH] Clarify __atomic_compare_exchange_n docs

Jonathan Wakely jwakely@redhat.com
Thu Oct 1 18:35:00 GMT 2015


On 01/10/15 11:57 -0600, Sandra Loosemore wrote:
>Hmmmm, yes.  Looking at the section as a whole, is it a bug in the 
>implementation that the built-ins only "approximately match" the C++11 
>requirements?

AFAIK they exactly match, so I don't know why the docs say that.

>If there were an exact correspondence, it would only be 
>necessary to point at the standard (I think it would be more helpful 
>to mention <stdatomic.h> here than to cite a specific section number), 

That's the C11 header, the C++11 header is <atomic>.

>identify what C++11 names the built-ins map onto,

It's pretty straightforward, I'm not sure we need to say much:

__atomic_xxx(_n)? -> atomic_xxx


>and to document any 
>implementation-defined behavior allowed by the standard and GCC 
>extensions.

There is nothing implementation-defined in the atomics clause, just
some wooly requirements like "Implementations should make atomic
stores visible to atomic loads within a reasonable amount of time."



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