Re: [patch] Fix uninitialized section index internal error

[Elena Zannoni <ezannoni@cygnus.com>]

Joel Brobecker writes:
 > Hi Elena,
 > 
 >   thank you very much for reviewing this patch.
 > 
 > > I see what's happening, your symbol is in section scSBss and not in scBss.
 > > This macro in mdebugread.c:
 > > SC_IS_BSS(sc) ((sc) == scBss || (sc) == scSBss)
 > > 
 > > evaluates to true, so you get to execute:
 > > 
 > > 	  else if (SC_IS_BSS (ext_in->asym.sc))
 > > 	    {
 > > 	      ms_type = mst_bss;
 > > 	      svalue += ANOFFSET (objfile->section_offsets, SECT_OFF_BSS (objfile));
 > > 
 > > or (a few lines below):
 > > 
 > > 	  else if (SC_IS_BSS (ext_in->asym.sc))
 > > 	    {
 > > 	      ms_type = mst_file_bss;
 > > 	      svalue += ANOFFSET (objfile->section_offsets, SECT_OFF_BSS (objfile));
 > > 	    }
 > > 
 > > 
 > > The SECT_OFF_BSS then is -1. It shouldn't be used in this case,
 > > because the symbol may not be in the bss section.
 > > 
 > > That said, may I suggest a different approach?  I think the bug is
 > > really in mdebugread.c, not symfile.c.  I think the SC_IS_BSS macro
 > > should be split in 2 separate ones: a proper SC_IS_BSS and another
 > > SC_IS_SBSS for your case.  Then the above code would work ok, if you
 > > don't have the .bss section, because it wouldn't trigger.  As for the
 > > SC_IS_SBSS case, you would have to figure out what the correct value
 > > to be added to svalue needs to be, and for this you need to find the
 > > index of the .sbss section.
 > 
 >   Ok, our patch was based on the assumption that the .bss and .sbss
 > sections were mutually exclusive. Your approach is more solid. 
 > 
 > May I suggest then to go a little further with your approach, which
 > cries out for the addition of a new sect_index_sbss in the objfile
 > structure:
 >   - in struct objfile (objfiles.h), add a new section index called
 >     sect_index_sbss
 >   - still in objfiles.h, add a new SECT_OFF_SBSS macro
 >   - initialize the sbss section index in default_symfile_offset
 >     (symfile.c) at the same time we're initializing the indexes of
 >     the other common sections
 >   - in mdebugread.c, fix the SC_IS_BSS macro, add a new SC_IS_SBSS
 >     macro, and then update the parse_partial_symbols () procedure
 >     to use the .sbss section if the symbol is there
 > 
 > If you agree with this approach, I'll then submit the new patch.

Joel,
Sorry, but we are trying to move away from having gdb knowing that
some sections are special. Adding a new SECT_OFF_SBSS macro, would not
be in line with that. Would you mind just doing that bit I suggested?
That would solve your immediate problem, right?

Thanks a bunch

Elena


 > 
 > Thanks,
 > -- 
 > Joel
 >