By "the entire thing", do you mean an entire file, without knowing if all functions in it will be used? I'm just baffled because there are several posts here from V8 developers, and quotes from the FAQ, saying things of the form "this is like FullCodeGen, except X", and the "X" is never "FullCodeGen was not a JIT". Which suggests to me that the people closest to development of these things don't think of them in the same terms as you do, which is why I'm trying to understand your terms.