Hello,
I just pushed a somewhat big commit to the CPS branch. It didn't have much content, but it moved register allocation to its own file. It also tries to move in the direction of making logically separate operations into their own passes, which Andy wanted.
I think it's mostly good, but I would be interested in reviews of the interface between allocate-registers-and-labels and the rest of the program. The trouble is, it sets a lot of different properties, and therefore returns six values. I could make labels and registers into a separate pass, but we'd still have one pass returning two values and another pass returning four.
Another possibility is packaging everything up into a struct. The reason I didn't do that is that the first thing I would do with that struct is extract all of its elements, so it seemed like extra work for not much benefit. I don't know of any reason we need to be able to store the state of a partially-run compiler right now.
The old way of handling this was having a bunch of global variables, but this seems cleaner and more functional. There might also be a fourth way that I haven't thought of, or maybe one of these three ways is clearly best. This isn't a big issue now, but it's going to be important to organize passes well as the compiler grows more and more of them.
Thanks,
Noah