[llvm-dev] spill to register not stack?

[Bagel via llvm-dev]

Given an architecture with two classes of registers: A is general purpose and 
has an "adequate" number of registers, and C which is special purpose and has 
very few (e.g. one) register.  There are cheap instructions that directly copy 
from C to A and vice versa.

If we need another C register and they are all live, we need to spill one. 
Currently as far as I can tell, the only way to do that is spill to the stack. 
Is there a knob I can turn to get the spill from C to go to an A register?

Thanks,
brian