how to implement general macro-insn expansion?

[Doug Evans]

Greg McGary writes:
 > I was striving to reuse existing mechanisms, make local labels and
 > pseudo-ops easily usable, which is best achievable by having
 > md_assemble() return an expansion.  Can you live with that?

Dunno.  Are we talking gas implementation or cgen design?

If all of this is just how you're going to implement something
in gas I don't care (much).  But I'd like to see how this will appear in cgen.