Re: [RFA] Work around binutils/15021

[Doug Evans <dje@google.com>]

On Thu, Jan 17, 2013 at 9:52 AM, Tom Tromey <tromey@redhat.com> wrote:
>>>>>> "Doug" == Doug Evans <dje@google.com> writes:
>
> Doug> Regression tested with gdb-generated .gdb_index version 7 (by hacking the
> Doug> gdb-under-test to generate version 7), version 8, with dwz, and with gold.
>
> I think index version bumps require a documentation update and also a
> binutils patch.

Blech.  Must remember to type grep foo *.texinfo instead of *.texi.

> Doug>   Work around binutils/15021
>
> IIUC, the version bump is part of the workaround for the gold bug,
> right?  The idea being that gold will generate version 7 indices,
> causing gdb to take the "inclusion" path.  (I'm just trying to make sure
> I understand what is going on.)

Yeah.  In the end I may not be able to avoid always having to record
the inclusions.
But to handle an app with 10k CUs and 530k TUs I'd to know if I *can*
avoid it before something goes into a spec that makes it really hard
or impossible.

> Doug> +     This is also used to work around a difference between the way gold
> Doug> +     generates .gdb_index version <=7 and the way gdb does.  Arguably this
> Doug> +     is a gold bug.
>
> To me it doesn't seem arguable, but I'm curious to know what the case is
> for it not being a gold bug.

I don't have a strong enough opinion on this.

> Doug> @@ -19634,7 +19660,7 @@ dwarf2_per_objfile_free (struct objfile
>
> Doug>    for (ix = 0; ix < dwarf2_per_objfile->n_comp_units; ++ix)
> Doug>      VEC_free (dwarf2_per_cu_ptr,
> Doug> -       dwarf2_per_objfile->all_comp_units[ix]->s.imported_symtabs);
> Doug> +       dwarf2_per_objfile->all_comp_units[ix]->imported_symtabs);
>
> If follow_die_sig can be called when one TU refers to another TU, then
> it seems like the TU could have a non-empty 'imported_symtabs', meaning
> that the loop here should also iterate over TUs.

Ah, righto.  Revised patch to follow.