> what's happening is that make_gen_semantics_list() is calling
> insn_list_insert() to insert the DMxC1_COP1Sb on to the semantics list
> (OK), but insn_list_insert finds that all of the keys it cares about
> are the same, thinks it's a duplicate of DMxC1_COP1Sa, and merges it
> into DMxC1_COP1Sa (not so OK), and as a result no semantic function is
> generated for DMxC1_COP1Sb.

Sounds like another key is needed (I keep adding them :-).

> I don't know what the right solution here is, but I figured others
> might want to be aware of the problem and might have comments.
> 
> Having talked w/ Andrew a bit about the future of the MIPS sim, it's
> going to move away from using -M like this, and instead use multiple
> igen runs to generate simulators for different machines.  So, this
> isn't something that I need a solution to.
> 
> I just wanted people who might care in the future to have a reference
> in the list archives.  If a solution comes out of this, well, that'd
> be fine by me, too.  8-)

Turns out that such instructions need to be given unique field-names as 
they would otherwise generate functions with the same name.  Just explot it.

See attached.  It works for your example.

	Andrew