Re: more dwarf_output stumbling

[Mark Wielaard <mjw at redhat dot com>]

On Mon, 2011-02-14 at 17:26 -0800, Roland McGrath wrote: 
> > So I am now looking at only calculating the local hash when we currently
> > finalize, but don't put the items directly in the cache, but only after
> > we scanned over the whole CU. That way when we do put the item in the
> > cache, we can calculate the full hash because we can be sure that all
> > dies that the reference attributes (recursively) points at have their
> > local hash set.
> 
> I can't tell whether that sounds like exactly what I always thought the
> plan of the new algorithm was, or sounds like you're still not changing the
> old way of doing things enough.

I am probably not changing enough, trying to not disturb the current
setup too much.

> "When we currently finalize" is based on all the dismal hairy bookkeeping
> that we ought to be getting rid of.

yeah, I am probably just bad at splitting out the necessary versus
dismal hairy parts.

>   In initial cut of the new plan,
> nothing actually gets finalized until the whole CU is being finalized.

So, the reason that I didn't do that directly was because only when we
finalize, do we create a die_info, which is necessary to hold the local
hash for each input die we transform to an output die and put into the
collector.

On my branch I now delay finalization till the whole CU is done in
final_unit (). In defined_self () a die_info with the local hash is
created (at which point all children exist and have their local hash
set). Then when the entry gets finalized all referenced entries already
have a die_info with a local hash set which can be used in calculating
the final hash.

This works for the small examples in tests/dwarf_edit_output. The
attributes_type hash is now calculated using all the local hashes of the
referenced dies in the attributes.

For the bigger examples in the testsuite with dwarfcmp-test -T it will
fail with a logic_error since it dwarfcmp detects that the input and
dwarf_output aren't equal. Next up is looking into that (I believe most
of these self-tests with dwarfcmp did also fail before/on the dwarf
branch proper).

Cheers,

Mark