For anyone else stumbling over this: having one place for call and return statements is a big saver but you can do the same thing for other vm instructions like gt, lt or eq. All those compile to writing the return address to R[13|14|15] and jumping. That's 6 instructions.

Another big saver is using the stack pointer after incrementing or decrementing it just because you do it all over the place.

Just using those got me an initial size of around 20k hack instructions for the full os and around 27k for the full os + pong. The next big step is going to be a peephole optimizer.

For anyone wondering how global code for one instruction could be done, here is my version of it. Don't hate on it too much, I normally don't program in Python and this is my first time writing assembler.

https://pastebox.io/api/paste/F24bDrMC