PR middle-end/18160

[Adam Nemet]

There is a mismatch between the front-end and the expander after this
patch by RTH:

2004-08-30  Richard Henderson  <rth@redhat.com> 
 
        * expr.c (expand_expr_addr_expr): New. 
        (expand_expr_real_1) <case ADDR_EXPR>: Use it. 

The patch seems to have removed the explicit handling of registers
from the expander.

The question is should the front-end mark the address expression of a
(local) register variable with an error_mark_node or should the
expander deal with it and assign it to memory like it used to.

I think it is the latter but I'd like to have some comments before I
prepare a patch.

Adam