Re: Limited success with 3.0 branch on AIX

[Elena Zannoni <ezannoni at cygnus dot com>]

Jim is away from his mail at the moment, but I just talked with him on
the phone about this. 

We were thinking about C_INFO as a possibility. Whether we use C_GSYM
or C_INFO, xcoffread.c will have to get the name of the symbol, but
C_INFO is much less likely to occur, thus the overhead would be less.

The definition of C_INFO is in /usr/include/storclass.h on an AIX
machine.  I saw it mentioned in a patch by Tom Rix on the binutils
mailing list, as well:
http://sources.redhat.com/ml/binutils/2001-01/msg00448.html

For the C_INFO, if we chose to go with that, we would have to write
similar code to what dbxread.c, process_one_symbol() does for N_OPT,
and that would go in xcoffread.c, read_xcoff_symtab() instead:

      /* We use N_OPT to carry the gcc2_compiled flag.  Sun uses it
         for a bunch of other flags, too.  Someday we may parse their
         flags; for now we ignore theirs and hope they'll ignore ours.  */
    case N_OPT:		/* Solaris 2:  Compiler options */
      if (name)
	{
	  if (STREQ (name, GCC2_COMPILED_FLAG_SYMBOL))
	    {
	      processing_gcc_compilation = 2;
#if 0				/* Works, but is experimental.  -fnf */
	      /* For now, stay with AUTO_DEMANGLING for g++ output, as we don't
		 know whether it will use the old style or v3 mangling.  */
	      if (AUTO_DEMANGLING)
		{
		  set_demangling_style (GNU_DEMANGLING_STYLE_STRING);
		}
#endif
	    }
	  else
	    n_opt_found = 1;
	}
      break;


Elena



Kevin Buettner writes:
 > On May 2, 11:24pm, Zack Weinberg wrote:
 > 
 > > > 	I do not see anything in the AIX equivalent to N_OPT -- no comment
 > > > storage class.  Would using N_GSYM (AIX's C_GSYM) be appropriate?  It
 > > > seems to be a stab for which only the name is significant, not the value,
 > > > which matches the use of gcc2_compiled.
 > > 
 > > The question is whether gdb on AIX will notice the marker in a C_GSYM
 > > .stabx directive; also whether the native debugger will choke on it.
 > > I've cc:ed the gdb folks for comment.  Leaving your patch quoted so
 > > they can look at it.
 > 
 > David asked about this on the GDB list recently.  I see nothing wrong
 > with David's approach, though GDB will require a minor modification to
 > recognize "gcc2_compiled." as an N_GSYM.
 > 
 > See:
 > 
 >     http://sources.redhat.com/ml/gdb/2001-05/msg00015.html
 >     http://sources.redhat.com/ml/gdb/2001-05/msg00019.html
 >     http://sources.redhat.com/ml/gdb/2001-05/msg00020.html
 >     http://sources.redhat.com/ml/gdb/2001-05/msg00027.html
 >     http://sources.redhat.com/ml/gdb/2001-05/msg00028.html
 >     http://sources.redhat.com/ml/gdb/2001-05/msg00030.html
 >     http://sources.redhat.com/ml/gdb/2001-05/msg00033.html
 > 
 > I will note, however, that neither of GDB's symtabs maintainers
 > have weighed in on this issue yet.
 > 
 > Kevin
 >