DWARF2 vs. 64-bit MIPS

[Mark Mitchell <mark@codesourcery.com>]

The 64-bit IRIX6 use of DWARF2 does not follow the published DWARF
documents I found on Intel's web-site.  In particular, look at the
beginning of this DWARF2 section from the 64-bit crt1.o:

.debug_info:

           	0000  0000  0000  0140  0002  0000  0000  0000  
           	0000  0801  2f78  6c76  3535  2f6b  7564  7a75  

There are *eight* (rather than four) bytes, indicating the length of
the debugging information, two bytes (as required) of DWARF version
information, and *eight* (rather than four) bytes of address offset,
followed by the single-byte value indicating the address size.

Contrast with the N32 version:

.debug_info:

           	0000  0106  0002  0000  0000  0401  2f78  6c76  

In order to handle this situation, it would seem that we need
parse_comp_unit to take the address size as a parameter, rather than
calculating it from looking at the debugging information.  Of course,
if no such size is provided, it could fall back on the method it uses
now, which matches the DWARF2 documentation.

Objections to such a patch, or suggestions for other approaches?

--
Mark Mitchell                   mark@codesourcery.com
CodeSourcery, LLC               http://www.codesourcery.com