Register names and dollar signs

[Greg McGary]

Basic question:

I wish to define a MIPS-like assembler syntax where register names and
numbers are prefixed with dollar signs, e.g., `$4' or `$a0'

I thought the proper way was via (indices keyword "$" ... ) in
define-hardware for the general registers, but it appears to have no
effect.  When I can change the prefix value and re-cgen, the files
don't change.  Smells like a bug?  What's the intended effect on the
output?  Set a prefix variable or macro?  Augment the register name
strings with the prefix?  I'll fix it if I know what it's supposed to
do.

Greg