From: Joost van der Sluis <joost@cnoc.nl>
To: gdb@sourceware.org
Subject: Re: Handling of c++ function members
Date: Mon, 26 Sep 2011 21:01:00 -0000 [thread overview]
Message-ID: <1317070857.17681.11.camel@feddie.cnoc.lan> (raw)
In-Reply-To: <CAN9gPaE0K+z-8H5NyHmHg2KcYz2QEAHOy=eXC28bva0-zD4xhg@mail.gmail.com>
On Mon, 2011-09-26 at 16:38 -0400, Daniel Jacobowitz wrote:
> On Mon, Sep 26, 2011 at 12:46 PM, Joost van der Sluis <joost@cnoc.nl> wrote:
> > Hi all,
> >
> > I've been looking at the code which handles calling c++ function members
> > and the Dwarf specifications. Is came to the conclusion that gcc does
> > not generate valid Dwarf-debuginfo for those function members, but a
> > work-around which is also implemented in gdb, namely in gnu-v2-abi.c.
> >
> > Is my conclusion right?
>
> Can you be a little more specific, maybe an example?
>
> There are definitely oddities in the GCC debug info, but the
> workarounds I remember are in the DWARF reader.
Problem is that I'm not sure is I read the Dwarf-spec's regarding
function members correctly.
What I understood is, that DW_AT_vtable_elem_location should contain a
Dwarf-block that calculates the location of a pointer in which the
location of the function member is stored.
But it seems to me that gcc stores the index of the function member
within some vtable in DW_AT_vtable_elem_location, instead of the memory
address itself. In gnu-v2-abi.c there is some code that 'knows' how this
vtable is organized so it is able to calculate the location of the
method-pointer.
And there are two thing's I'm not sure about: gcc stores
DW_AT_containing_type in the debug-info, with the 'parent' entry of the
DW_TAG_subprogram entry. To me it looks that this is duplicated
information, and not specified in the Dwarf-specs. Secondly I do not
understand where the DW_AT_object_pointer is used for?
Joost.
next prev parent reply other threads:[~2011-09-26 21:01 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-26 16:46 Joost van der Sluis
2011-09-26 20:38 ` Daniel Jacobowitz
2011-09-26 21:01 ` Joost van der Sluis [this message]
2011-09-27 15:05 ` Joost van der Sluis
2011-09-27 16:01 ` Joost van der Sluis
2011-09-30 14:42 ` Daniel Jacobowitz
2011-09-30 15:53 ` Joost van der Sluis
2011-09-30 18:50 ` Jan Kratochvil
2011-09-30 20:37 ` Joost van der Sluis
2011-10-02 13:51 ` Joost van der Sluis
2011-10-05 18:56 ` Tom Tromey
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