Petr Sorfa's Dwarf 2 changes

[Daniel Berlin]

> Not only will they agree, I believe Petr and John had already finished
> doing this.

>
And I did it before them.
>  Doubtless there's still some room for improvement, but the
> functionality is there...  John, do you have that merged dwarf2read
> available?
If they don't, you should be able to find mine in the archives.
Unless i'm misremembering Petr's, it keeps all the CU's around all the 
time.
One thing I did was to make it so you could throw away CU's at will, 
and it would just reread them if/when necessary (IE it would just keep 
the last 10 used CU's or something as a cache).   Cuts down on memory 
usage significantly with almost no loss in speed.

PS I remember someone mentioning something about not needing to 
basically rewrite the dwarf2 reader to do this, though, which is what 
"pretty pervasive changes" sounds like. Not that i'm bitter, i just 
find it funny. :)
Though i'm aware the retort will be that i did more than necessary 
(like mmapping the symbol files, and the ever controversial duplicate 
removal).

Jim, you should be able to just rip the pieces from the dwarf2 reader 
rewrite i had done, or Petr did, without any trouble.
> [For instance, from Petr's July posting:
>         * dwarf2read.c (build_die_ref): New function that builds
>           a new die reference if necessary, will search across
>           multiple comp units to find the reference.
>           (find_die_ref): New function that searches for a die
>           reference for a given comp unit.
>           (find_cu_header_from_begin_offset): New function that
>           searches through a link list of comp unit headers for
>           a comp unit that matches the given offset.
>  ]
>
> -- 
> Daniel Jacobowitz
> MontaVista Software                         Debian GNU/Linux Developer