Re: [PATCH] C++/DWARF : Add 'using' support - take 2

[Devang Patel <dpatel at apple dot com>]

On Jan 13, 2004, at 2:32 PM, Jason Merrill wrote:

> > > I'd prefer to do without all the changes to make gen_subprogram_die 
> > > return
> > > a value.  I don't see a good reason to break the convention of 
> > > "generate,
> > > then look up" for just this one variety of DIE.
> >
> > We do not equate abstract dies with decl number
>
> Huh?

Oops, I gave wrong reason. We do not equate declaration dies unless
it is for abstract functions. In force_decl_die() we do...

          if (DECL_INITIAL (decl) == NULL_TREE)
            /* Force die to represent this function declaration.  */
            decl_die = gen_subprogram_die (decl, context_die);

and in gen_subprogram_die() we have

  if (declaration)
    {
      if (!old_die || !get_AT (old_die, DW_AT_inline))
        {
          add_AT_flag (subr_die, DW_AT_declaration, 1);

          /* The first time we see a member function, it is in the 
context of
             the class to which it belongs.  We make sure of this by 
emitting
             the class first.  The next time is the definition, which is
             handled above.  The two may come from the same source 
text.  */
          if (DECL_CONTEXT (decl) || DECL_ABSTRACT (decl))
            equate_decl_number_to_die (decl, subr_die);
        }
    }

> > > You should handle this in the "else if (old_die)" block below, which 
> > > also
> > > deals with reusing a die.
> >
> > It handles reusing decl die as definition die. We need to complete 
> > this
> > die which is the else section after "else if (old_die)".
>
> What do you mean by "complete"?  The die created by force_decl_die 
> should
> be a declaration die, so reusing it as a definition die should be what 
> we
> want.

We also force abstract function dies.

> > > I don't see how checking die_definition makes any sense here.  What
> > > situation is this code trying to handle?
> >
> > If variable for forced out earlier than later on 
> > add_AT_specification()
> > aborts because die_definition is non-zero.
>
> Why is it non-zero?

Because die for variable is already forced out. I just need a check
to skip it next time.

> > > > ! force_decl_die (tree decl)
> > > > ! {
> > > > ...
> > > > ! 	  else if (DECL_INLINE (decl))
> > > > ! 	    /* Force die to represent this function as abstract
> > > > ! 	       function for our reference.  */
> > > > ! 	      dwarf2out_abstract_function (decl);
> > >
> > > I realize that I suggested this in my earlier review, but I think we
> > > shouldn't handle inline functions differently here.  If all we care 
> > > about
> > > is having a DIE to refer to, we don't need to emit the whole abstract
> > > function.
> >
> > so instead what do you suggest here?
>
> I think we want to force a declaration die in all cases, regardless of
> whether or not the function has been defined.  I'm reluctant to change 
> the
> order in which definition dies are emitted.

I think, I tried that but did not work out well for inlines hence
you suggested to emit die to represent abstract function. Anyway, I'll
give it another shot.

Thanks,
--
Devang