Re: [PATCH][WIP] dwarf2out: extend to output debug section directly to object file during debug_early phase

[Jan Hubicka <hubicka@ucw.cz>]

> > > +  output_data_to_object_file (1, 0);
> > > +  output_data_to_object_file (1, 0);
> >
> > So this basically renames dw2_asm_output_data to
> > output_data_to_object_file and similarly for other output functions.
> >
> > What would be main problems of making dw2_asm_* functions to do the
> > right thing when outputting to object file?
> > Either by conditionals or turning them to virtual functions/hooks as
> > Richi suggested?
> >
> I think it's doable via conditionals. Can you explain the second approach
> in more detail?

Basically you want to have output functions
like dw2_asm_output_data to do the right thing and either store
it to the LTO simple object section or the assembly file.
So either we can add conditionals to every dw2_asm_* function needed
of the form
  if (outputting_to_lto)
     ... new code ...
  else
     ... existing code ...

Or have a virtual table with two different dw2_asm implementations.
Older GCC code uses hooks which is essencially a structure holding
function pointers, mostly because it was implemented before we converted
source base to C++. Some newer code uses virtual functions for this.
> > > +struct lto_simple_object
> > lto_simple_object is declared in lto frontend.  Why do you need to
> > duplicate it here?
> >
> > It looks like adding relocations should be abstracted by lto API,
> > so you don't need to look inside this structure that is
> > lto/lto-object.cc only.
> >
> I should have taken this approach, but instead, I exposed simple objects to
> dwarf2out.
> That's the reason to duplicate the above struct. I will take care of this
> while refactoring
> and abstracting it by lto API

Yep, this should not be hard to do.

Thanks for all the work!
Honza
> 
> 
> >
> > > +/* Output one line number table into the .debug_line section.  */
> > > +
> > > +static void
> > > +output_one_line_info_table (dw_line_info_table *table)
> > It is hard to tell from the diff.  Did you just moved these functions
> > earlier in source file?
> >
> Yeah. I will refactor the dwarf2out soon to clear these confusions.
> 
> -- 
> Rishi
> 
> 
> >
> > Honza
> >