Multiple ISAs for opcodes

[Doug Evans]

Ben Elliston writes:
 > Hi,
 > 
 > I posted a question to the list some weeks ago and received no responses of
 > substance -- that surprises me.  Rather than type my message again, here is
 > a link to the archived original:
 > 
 > 	http://sources.redhat.com/ml/cgen/2000-q4/msg00031.html
 > 
 > So -- any thoughts?

This is new ground (albeit barely).  What seems reasonable?

You could either have one enum that contains everything,
or you could generate two opc.h's, one for each ISA.
In and of itself, I prefer the latter.