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Re: [vta->trunk] VTA merge
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Mark Mitchell <mark at codesourcery dot com>
- Cc: Tom Tromey <tromey at redhat dot com>, Alexandre Oliva <aoliva at redhat dot com>, "Joseph S. Myers" <joseph at codesourcery dot com>, Jack Howarth <howarth at bromo dot med dot uc dot edu>, Steven Bosscher <stevenb dot gcc at gmail dot com>, Richard Guenther <richard dot guenther at gmail dot com>, gcc-patches at gcc dot gnu dot org
- Date: Fri, 4 Sep 2009 09:20:39 +0200
- Subject: Re: [vta->trunk] VTA merge
- References: <m3tyzp483d.fsf@fleche.redhat.com> <20090830155630.GA31476@bromo.med.uc.edu> <571f6b510908300940ncaebad1q43b157a387e01e30@mail.gmail.com> <20090830175027.GA1966@bromo.med.uc.edu> <Pine.LNX.4.64.0908301753480.6056@digraph.polyomino.org.uk> <oreiqq4b7e.fsf@huru.localdomain> <m3my5dme9h.fsf@fleche.redhat.com> <orljkwxzxj.fsf@huru.localdomain> <m3pra8ghwh.fsf@fleche.redhat.com> <4AA06A6E.3060103@codesourcery.com>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Thu, Sep 03, 2009 at 06:16:30PM -0700, Mark Mitchell wrote:
> Tom Tromey wrote:
>
> > I don't know about other debuggers, but GDB will issue an error like:
> >
> > Unhandled dwarf expression opcode 0x9e
> >
> > if you try to print a variable whose location uses that opcode.
>
> That's unfortunate. Obviously, we can't do anything about older
> versions of GDB, but can we change GDB so that it doesn't complain and
> just silently ignores the expression, unless in some debugging mode? If
> I'm a user, and I have some compiler that spits out weird DWARF GDB
> doesn't understand, scary messages aren't helping me.
Yes, it is unfortunate. But we can't retroactively change released GDBs,
and the upcoming GDB will understand it. And you need the upcoming GDB to
debug GCC 4.5 compiled code anyway, because older GDBs mishandle
DW_CFA_restore_state which is now used all around in .eh_frame, otherwise
backtraces really don't work.
Jakub