double gimplification in C++ FE

[Aldy Hernandez]

> Yes, the gimplifier often makes several passes over the same trees to get 
> them completely lowered.  cp_gimplify_expr is a subroutine of the 
> gimplifier.

Good, I just wanted to make sure I wasn't off my rocker or anything.

> Sure.  Another alternative would be to leave the calls to gimplify_stmt (or 
> probably change them to gimplify_to_stmt_list) and return GS_ALL_DONE from 
> cp_gimplify_expr.

Yes, in a few places it definitely seems better to completely gimplify
the given statement and return GS_ALL_DONE.  Will do so when it's
easier.

Heads up.

Thanks.
Aldy