Who's afraid of a big bad optimizing compiler?

I agree. Although I still don't understand why the C11/C++11 memory model chose to provide barriers not tied to variables in such an oddly defined way. IIRC - and it's been a while since I tried to parse the standard's language - you can't really use them to incrementally upgrade from compiler-specific barriers, without also converting all other memory to go through C11/C++11 atomics.