atomic accesses

[Andrew Haley]

Segher Boessenkool wrote:
>> As I said before, I think any words of this form SHOULD NOT be added.
>> All it does is add words to the documentation that provide NO
>> guarantee of anything -- but in a way that will confuse those who
>> don't read it carefully enough into thinking that they DID get some
>> sort of guarantee.
> 
> The idea is to _do_ provide that guarantee.  If the GCC code does not agree
> with the GCC documentation, the code has a bug ;-)
> 
>> In other words, a statement like that has clear negative value.
> 
> I disagree.  People are relying on this undocumented GCC behaviour already,
> and when things break, chaos ensues.  If we change this to be documented
> behaviour, at least it is clear where the problem lies (namely, with the
> compiler), and things can be fixed easily.
> 
> The two big questions are:
> 
> 1) Do we *want* to guarantee any behaviour in this area?
> 
> 2) Exactly *what* behaviour?

This would ba a gcc extension.  History does not favour such extensions:
we've been unable to define them well enough, for one thing.

Andrew.