"Whole-program analysis is not tractable (i.e., not scalable)," The search term for those who'd like to follow up is "Superoptimization", which is one of the p

"Whole-program analysis is not tractable (i.e., not scalable)," The search term for those who'd like to follow up is "Superoptimization", which is one of the perennial ideas that programmers get that will Change the World if it is "just" implemented and "why hasn't anyone else done it I guess maybe they're just stupid", except it turns out to not work in practice. In a nutshell, the complexity classes involved just get too high. (An interesting question I have is whether a language could be designed from the get-go to work with some useful subset of superoptimizations, but unfortunately, it's really hard to answer such questions when the bare minimum to have a good chance of success is 30 years of fairly specific experience before one even really stands a chance, and by then that's very unlikely to be what that person wants to work on.)