Re: gdb supports dwarf2 which is generated by ADS compiler?

[Jim Blandy <jimb@redhat.com>]

"Jang, Jaewoo" <jaewoo.jang@aromasoft.com> writes:
> I try to debug elf dwarf2 format whcih is generated by ADS 1.0.1 compiler.
> It seems that gdb support dwarf2 spec.
> But ARM dwarf2 spec is somehow modified from drawf2 spec.
> This is the reference of ARM dwar2 spec.
> http://www.linuxbase.org/spec/refspecs/dwarf/ARMDwarf2.pdf
> 
> I want to know whether gdb will support ARM dwarf2 format,
> or it is possible to patch gdb that support ARM dwarf format.
> Now I try to understand source codes that is part of reading elf format.
> It is hard to understand. :(

The differences described in section 4 of that document sound like
pretty serious divergences from the Dwarf 2 spec.  ARM Dwarf 2 creates
multiple .debug_info sections, one for each source file, with names
suffixed by the source file name.  This affects the way name lookup is
performed:

    This organisation makes the debugger's job in performing name lookup
    more complex. With a single debug table per object it need merely
    identify the place within the single table describing the function
    definition containing the current pc, and work backward and outward
    through the nested scopes described by the table. In the ARM DWARF2
    organisation, it needs to do that first, but then needs to look
    through the tables for files containing the function definition or
    included from those files, and the other debug sections describing
    sections generated from those files. This is possible because:

    - the .debug_line table in the set of tables describing a file
      contains both the name of the file and the names of the files it
      directly includes

    - the .debug_line table in the set of tables describing a code or data
      section contains the name of all files defining entities included in
      the section.

    The order of declarations and definitions can be reconstructed, since
    source position information is present for all definitions and
    declarations, and also the source position of #include directives is
    described in macro information tables.

GDB certainly can't read Dwarf 2 information arranged in this way at
the moment.