[cpp-threads] Web site updated

[Peter Dimov]

Boehm, Hans wrote:
>> MMIO accesses, anyone?  Hardware timing analysis (especially
>> if there is a short loop between the two)?
>>
>> Let's please just outlaw that sort of optimization for
>> store_raw(), so that it can retain its full meaning.
>>
> My understanding is that we are constrained here as to what we can
> require in normative standards text.

Even if we aren't so constrained, do we really want to forbid these 
optimizations?

atomic_fetchadd_relaxed( &cnt, +1 );

// ordinary ops 1

atomic_fetchadd_relaxed( &cnt, +1 );

// ordinary ops 2

atomic_fetchadd_relaxed( &cnt, +1 );

I'd really like the MM to be enlightened/permissive enough as to allow

// ordinary ops 1+2

atomic_fetchadd_relaxed( &cnt, +3 );

here. (This should work even for _release because moving in one direction is 
still allowed; not for the various flavors of _ordered, though.)

Similarly,

atomic_fetchadd_relaxed( &cnt, r );
atomic_fetchadd_relaxed( &cnt, -r );

should be a noop, even for _ordered.

> I am less clear as to what we can reasonably suggest as nonbinding
> notes in the standard.

We are free to suggest pretty much anything in notes, examples and 
footnotes, as long as it doesn't contradict the normative text.