[LLVMdev] Instructions on a target with no general purpose registers

[Edwin Amsler]

I've mentioned my sneaky plans to target the MOS6502 here before.

The big issue I think is that a lot of instructions don't really have a choice for output register. It all just goes into the accumulator, X index, or Y index based on the specific instruction.

So, my question is, when I'm defining my ins, outs and registers for these instructions, is it going to be a problem that different instructions outputs are defined by the function that is called? And I guess, how do I tell LLVM it can't pick any old register for a given instruction?

Thanks,

Edwin