[arielb1]

> Compiler writers actually have it pretty easy once the language is defined, which is a real honest to god spec.

Compilers are typically developed in-parallel with the spec, exactly because you don't know what you want to spec before you try it out.

Optimizers have it even worse - they do not have much of a spec beyond "make it fast, quickly", so all development is trying to find interesting places in existing code.