Hi Jason.  Hi Richard.

While adjusting the limbdo_die_list for early debug I noticed we weren't 
early generating C++ constructors/destructors.  This got me on a detour 
of sorts.

I noticed dwarf2out's gen_member_die() disallows generation of clones 
earlier, by design:

      /* Don't include clones in the member list.  */
      if (DECL_ABSTRACT_ORIGIN (member))
        continue;

I played around trying to disable this "feature", but my approach ran 
into various walls, and I decided instead to attack it from the 
front-end side. The attached patch generates early DIEs for the C++ 
clones in the C++ parser. I'd be (un)happy to revisit the dwarf2out 
approach if it's deemed more appropriate.

Now back to limbdo_die_list... My approach is to flush the limbo list, 
generically, after the front-ends have finished, by adding a new 
"early_finish" debug hook.  This gets rid of any permanence into LTO 
time.  Then I flush it out again, if the middle end (or LTO, etc) has 
added any limbo DIEs.  I wish we didn't need to flush the limbo list 
past the compilation proper, but some things like Cilk+ generate 
function trees way late in the game, so we end up generating limbo DIEs 
past where I'd like to.  Please see the comment in the source code.

All in all, this patch should get rid of any middle-end dependence on 
the early debug generated limbo DIEs.

Are you happy with this?  I'd like to get your input before committing 
to this approach.

Thanks.
Aldy