54.

No Sane Compiler Would Optimize Atomics

www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4455.html

The paper’s claim:

False.

Compilers do optimize atomics, memory accesses around atomics, and utilize architecture-specific knowledge. This paper illustrates a few such optimizations, and discusses their implications.

Interestingly, none of the optimizations proposed in the paper actually work on GCC or Clang.