On Sat, Feb 15, 2014 at 9:45 AM, Torvald Riegel [off-list ref] wrote:

I think a major benefit of C11's memory model is that it gives a
*precise* specification for how a compiler is allowed to optimize.

Clearly it does *not*. This whole discussion is proof of that. It's
not at all clear, and the standard apparently is at least debatably
allowing things that shouldn't be allowed. It's also a whole lot more
complicated than "volatile", so the likelihood of a compiler writer
actually getting it right - even if the standard does - is lower.
They've gotten "volatile" wrong too, after all (particularly in C++).

           Linus