I think at least regarding concurrency, most developers need to rely on a model that is "good enough". You can't know everything, therefore you need to contend

I think at least regarding concurrency, most developers need to rely on a model that is "good enough". You can't know everything, therefore you need to contend with knowing at least enough that is necessary to do your work. Thinking that atomics will not be optimized by compiler is "good enough" in my opinion for almost, and I really mean almost, everybody. Heck, I interview people and atomics optimization is one of my staple questions (Tell me, what does volatile do in Java, exactly?). I have never heard a thorough answer to that question and yet people do work as developers and do produce working applications. The only real users of these optimizations are atomics primitives developers, and the use it to improve them a tiny bit in some special cases. You can technically contrive a test where you run an update that changes something to 1, then immediately to 2 on each iteration. Then you try to look at it from another core and you would expect that at least once in a blue moon you will see 1. But I just don't see any sanely written application to rely on that kind of behavior.