RFC: Variables in blocks of registers

[Daniel Berlin]

>
> However, right now GCC doesn't generate this.  Probably because it
> would kill us.  If I have any mental energy left after location lists,
> I may implement support for DW_OP_piece.

Err, the location list patch does.
Even without it, you can get them in one specific case (If you have
CONCAT's in RTL).
So GCC *does* generate it, right now.

CONCATS only pop up when we are using complex numbers, as far as a quick
grep of the gcc code shows.

--Dan