[sroussey]

> We already have specialised hardware for register mapping (which could be done in software, by the compiler, but generally isn't)

Wait, what? I’ve been out of compiler design for a couple decades, but that definitely used to be a thing.

[namibj]

They're probably referring to AMD Zen's speculative lifting of stack slots into physical registers (due to x86, phased out with Zen3 though), and more generally to OoO cores with far more physical than architectural registers.

[wizzwizz4]

We do register allocation in compilers, yes, but that has surprisingly little bearing on the actual microarchitectural register allocation. The priority when allocating registers these days is, iirc, avoiding false dependencies, not anything else.