[cpp-threads] C++ memory model

[Peter Dimov]

Nelson, Clark wrote:
> At this point it would be helpful if the person who wrote that
> sentence would please stand up and explain it. :-)

I didn't write the sentence, but I think I can explain it. It says that, 
while a finite sequence of atomic loads from the same location can be 
collapsed into a single atomic load from that location, an infinite sequence 
cannot be (similarly for stores of the same value to the same location).

The sentence is redundant and can be turned into a note if the previous 
sentence:

"Implementations should make atomic stores visible to atomic loads within a 
reasonable amount of time."

is made to use "shall" instead of "should".