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[dmj+@andrew.cmu.edu: Re: C++ debugging progress]
- From: Daniel Jacobowitz <drow at mvista dot com>
- To: libstdc++ at gcc dot gnu dot org, gdb at sources dot redhat dot com
- Date: Wed, 28 Nov 2001 15:19:08 -0500
- Subject: [dmj+@andrew.cmu.edu: Re: C++ debugging progress]
Feh. Meant to send this to the lists.
----- Forwarded message from Daniel Jacobowitz <dmj+@andrew.cmu.edu> -----
Date: Wed, 28 Nov 2001 15:18:19 -0500
From: Daniel Jacobowitz <dmj+@andrew.cmu.edu>
Subject: Re: C++ debugging progress
To: Jason Merrill <jason@redhat.com>
On Wed, Nov 28, 2001 at 07:40:37PM +0000, Jason Merrill wrote:
> >>>>> "Daniel" == Daniel Jacobowitz <drow@mvista.com> writes:
>
> > On Wed, Nov 28, 2001 at 09:31:07AM +0000, Jason Merrill wrote:
>
> >> So you're using the inheritance information in the RTTI rather than the debug
> >> info? That seems unfortunate. I'm not sure why you would need to worry
> >> about ordering; the debug info should tell you exactly where things are.
> >> If it doesn't, it should probably be fixed.
>
> > In that case, the debug info absolutely needs to be fixed.
>
> > <1><22e>: Abbrev Number: 15 (DW_TAG_structure_type)
> > DW_AT_sibling : <2df>
> > DW_AT_name : Left
> > DW_AT_byte_size : 12
> > DW_AT_decl_file : 1
> > DW_AT_decl_line : 2
> > DW_AT_containing_type: <22e>
> > <2><23f>: Abbrev Number: 22 (DW_TAG_inheritance)
> > DW_AT_type : <56>
> > DW_AT_data_member_location: 2 byte block: 23 8 (DW_OP_plus_uconst: 8; )
> > DW_AT_virtuality : 1 (virtual)
> > DW_AT_accessibility: 1 (public)
>
> Yep. Since Base is a virtual base of Left, the DW_AT_data_member_location
> here should be a complex expression telling the debugger to go through the
> vtable. I'll get on it.
Thanks!
> I'll also change the stabs output to give the offset within the vtable
> rather than the offset of the base in a complete object; gdb will still
> need to be clever enough to know what to do with it.
<delete lots of incoherent rambling>
OK, if I'm reading this at all correctly, the offset in the baseclass
definition is assumed to be 0 for a virtual baseclass, and ignored; it
is assumed that there will be a $vb later. So that offset slot is a
perfect place to put the information I need. Just let me know if it is
relative to the start of the vtable or to the vtable pointer. That'll
be enough information to do a much better job.
--
Daniel Jacobowitz Carnegie Mellon University
MontaVista Software Debian GNU/Linux Developer
----- End forwarded message -----
--
Daniel Jacobowitz Carnegie Mellon University
MontaVista Software Debian GNU/Linux Developer