[rfa] classes, partial symtabs, and DW_AT_specification

[David Carlton]

On Sun, 25 Jan 2004 12:00:31 -0500, Daniel Jacobowitz <drow@mvista.com> said:
> On Fri, Jan 23, 2004 at 04:40:48PM -0800, David Carlton wrote:

>> This is a serious design problem with our psymtab structure, which
>> we've known about for a while.  Either we need to add into it a
>> fast way to follow DW_AT_specification links _and_ then figure out
>> the parent of the die at the other end, or we need help from the
>> compiler, or something.  In any event, any correct solution would
>> be a major undertaking; the best way to deal with the situation for
>> now is to use demangled names when we run into this situation, just
>> like we would if the compiler weren't generating DW_TAG_namespace
>> at all.

> I have no objection to this as a workaround, although it makes me feel
> a bit filthy :)

I know the feeling...

>> OK to commit?  I guess I need symtab approval, though Daniel should
>> feel free to chime in as well. :-) And at some point we really need to
>> develop a plan of attack for DWARF-2 partial symbols - what
>> improvements can we do without GCC's help, what help do we want from
>> GCC?

> We don't need anything from GCC.  We have everything we need already;
> we just need to do things (very) differently.

Yeah.  For the issue I ran into, it's probably not _too_ hard to
solve: we could build up a die->parent table that only covered the
dies that we would want to parse while reading the psymtabs - the spec
die that I'm looking for should already be such a die.  But using this
as an excuse to step back and think about how we want dwarf2 psymtabs
to work in an ideal world would certainly be a good idea.

> I am working on inter-CU reference support again; if we can't find
> parents then there's no point in building psymtabs, since we won't
> be able to cope with the first reference to another CU that isn't
> nested directly under the CU DIE.

Ah.

> With a little tuning, I think this is a solvable problem.  It will
> probably take a speed hit, but smaller debug info will hopefully
> make up for a lot of that.  And then, if someone implements
> .debug_info_index, we can use that for psymtabs instead.

Do you have a reference for .debug_info_index?  I tried searching for
it, but nothing turned up; I couldn't find an archive for the dwarf2
mailing list.

David Carlton
carlton@kealia.com