Mutation and the need for a register allocator

[ix]

A problem - it is theoretically possible with Lazyboy at present to mutate the value of a register as it is being used in something, such as a loop.

I'm writing this on a whim and not testing it, so it could have mistakes, but the general idea is the same.

.a_loop
  ;; some code that modifies A
  sub 1 ;; A--
  jr nz, .a_loop 

To prevent this we could track which registers are in use in a scope and prohibit mutable access to them. Alternatively, we could silently allow them to be mutated, but move the value they have into a free register or create a map-like structure. After the inner code is executed, we can then move the value back into them before it's needed again.

[ix]

I've been (slowly) learning about SSA and such, I'll come back to this soon, I just work full time now, so finding time is a little harder than it used to be.