[lldb-dev] Problem with large sym files

[Greg Clayton]

> The problem is that we're back at square number one, I still get an error
> message from dsymutil while extracting the symbols from the main
> executable:
> 
> 	error: unable to restore file position to 0x00000c58 for section
> __DWARF.__debug_info
> 
> Any other ideas?

Does this happen every time? Or just some of the time? Mach files have a 4 GB limit of the section size, I hope you aren't getting close to that limit? 

dwarfdump has a really goofy option I added to track such issues where you can display file data for your executable and all .o files. You run this on your executable (not your dSYM):

% dwarfdump --show-children --file-stats a.out
 File       symtab            strtab            code data         DWARF debug       STABS debug       other             file
 ---------  ----------------- ----------------- ----------------- ----------------- ----------------- ----------------- ---------------------------------------
      9104        192   2.11%       166   1.82%      1187  13.04%         0   0.00%       202   2.22%      7357  80.81% a.out (i386)
      4040         84   2.08%        73   1.81%       915  22.65%       917  22.70%         0   0.00%      2051  50.77% /tmp/main.o (i386)
 =========  ================= ================= ================= ================= ================= ================= =======================================
     13144        276   2.10%       239   1.82%      2102  15.99%       917   6.98%       202   1.54%      9408  71.58%

It basically looks into your main executable and finds all of the .o files from the debug map and prints out stats at the end. You should run this on your main executable and see what the totals come out to. 

If you are able to get a dSYM file, you can view its section sizes:

% dwarfdump -R /tmp/large.dSYM
...
__debug_abbrev   __DWARF          011ac000 00002278 00379000 00000000 00000000 00000000 00000000 00000000 00000000    8.62K  0.00%
__debug_aranges  __DWARF          011ae278 0004b098 0037b278 00000000 00000000 00000000 00000000 00000000 00000000  300.15K  0.12%
__debug_frame    __DWARF          011f9310 0014fd24 003c6310 00000000 00000000 00000000 00000000 00000000 00000000    1.31M  0.52%
__debug_info     __DWARF          01349034 0bc4a338 00516034 00000000 00000000 00000000 00000000 00000000 00000000  188.29M 75.15%
__debug_inlined  __DWARF          0cf9336c 00229b4f 0c16036c 00000000 00000000 00000000 00000000 00000000 00000000    2.16M  0.86%
__debug_line     __DWARF          0d1bcebb 00822243 0c389ebb 00000000 00000000 00000000 00000000 00000000 00000000    8.13M  3.25%
__debug_loc      __DWARF          0d9df0fe 0068d8f4 0cbac0fe 00000000 00000000 00000000 00000000 00000000 00000000    6.55M  2.62%
__debug_pubnames __DWARF          0e06c9f2 002b42e1 0d2399f2 00000000 00000000 00000000 00000000 00000000 00000000    2.70M  1.08%
__debug_pubtypes __DWARF          0e320cd3 00eec229 0d4edcd3 00000000 00000000 00000000 00000000 00000000 00000000   14.92M  5.96%
__debug_ranges   __DWARF          0f20cefc 00484c78 0e3d9efc 00000000 00000000 00000000 00000000 00000000 00000000    4.52M  1.80%
__debug_str      __DWARF          0f691b74 00cee6d0 0e85eb74 00000000 00000000 00000000 00000000 00000000 00000000   12.93M  5.16%


Let me know how big things are on your end when you get the chance.

Greg Clayton