Re: C++0x Memory model and gcc

[Albert Cohen <Albert dot Cohen at inria dot fr>]

Jean-Marc Bourguet wrote:
> >     -fmemory-model=single
> >         Assume single threaded execution, which also means no signal
> >         handlers.
> >     -fmemory-model=fast
> >         The user is responsible for all synchronization.  Accessing
> >         the same memory words from different threads may break
> >         unpredictably.
> >     -fmemory-model=safe
> >         The compiler will do its best to protect you.
>
> With that description, I'd think that "safe" lets the user code assumes
> the sequential consistency model.  I'd use -fmemory-model=conformant or
> something like that for the model where the compiler assumes that the user
> code respect the constraint led out for it by the standard.  As which
> constraints are put on user code depend on the languages -- Java has its
> own memory model which AFAIK is more constraining than C++ and I think Ada
> has its own but my Ada programming days are too far for me to comment on
> it -- one may prefer some other name.

I agree. Or even, =c++0x or =gnu++0x

On the other hand, I fail to see the differen between =single and =fast, 
and the explanation about "the same memory word" is not really relevant 
as memory models typically tell you about concurrent accesses to 
"different memory words".

Albert