It’s misleading to say that register machines carry no liveness or that they defeat liveness. That’s a bit much. Computing liveness on a register machine with d

It’s misleading to say that register machines carry no liveness or that they defeat liveness. That’s a bit much. Computing liveness on a register machine with dense integer numbering of locals is not that expensive. It’s certainly cheaper than running a good backend. And a good backend will certainly modify the code in a way that requires liveness to be recomputed. It’s also misleading to say that register machines defeat SSA. It’s not hard to convert from a register machine to SSA - the algorithm is almost linear. Powerful backends (like WK’s B3) recompute SSA after some transformations anyway. I think that wasm combines elements of a stack machine and a register machine in a way that leads to a compact format and multiple reasonable paths to converting to the sort of IR you’d want for converting a platform agnostic form like wasm into any contemporary instruction set. I’m no wasm fanboy but as far as binary IRs for transporting code into optimizing compilers go, this one is pretty slick.