Atomic is available in C1X.
Yes, my motivation is that I've talked to multiple C++ compiler
developers lately and basically everyone is worried about how the new
memory model interacts with their optimizer. It's safe to say they'll be
flushing out subtle bugs for several years, but we could accelerate that
process.
What about inline? You will probably need to look at what kinds of
functions get inlined. There is lots of stuff you could stress,
eg, simplification when arguments are literal, optimization
opportunities in different calling contexts and stack handling
for different amounts of local storage.
Generating inline directive is a great idea, and (like "register") it's
totally free at generation time.