[olliej]

JITs have very different constraints (but also many advantages) vs AOT compilers, so I don't think in the general case a language compiler can "support" JITs directly. llvm/clang for instance have a jit mode... for compiling C/C++, not some other language.

Also obviously the compiler writers (AOT or JIT) need to know about and understand very minute details of how a cpu is behaving. I was responding to a person saying it was worrying that devs need that kind of knowledge and experience by saying that that isn't true because the tools exist (I feel that there's some analogy to what knowledge you need for a car: changing oil, servicing engine, replacing engine, designing an engine...). Once you are writing a JIT you're in the "making the tools" group, so you now need to know more than the vast majority of devs (not just more than the "average" dev) that's inescapable.