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Re: [PATCH] Re: Unwinding CFI gcc practice of assumed `same value' regs
- From: "Mark Kettenis" <mark dot kettenis at xs4all dot nl>
- To: "Jan Kratochvil" <jan dot kratochvil at redhat dot com>, gdb-patches at sourceware dot org
- Date: Wed, 13 Dec 2006 22:40:52 +0100 (CET)
- Subject: Re: [PATCH] Re: Unwinding CFI gcc practice of assumed `same value' regs
- References: <20061211190300.GA4372@host0.dyn.jankratochvil.net> <20061211224022.AD76E1800E7@magilla.sf.frob.com> <20061212155233.GH29911@devserv.devel.redhat.com> <20061213204603.GA11741@host0.dyn.jankratochvil.net> <20061213210357.GA27039@nevyn.them.org>
> On Wed, Dec 13, 2006 at 09:46:04PM +0100, Jan Kratochvil wrote:
> > Attaching patch for current gdb CVS to properly terminate on return
> > address 0.
> > The check was already present there but it got applied one backward step
> > later.
> >
> > I hope these three patches are be 100% reliable and also backward
> > compatible.
>
> Please read the previous discussion and patch on this topic:
> http://sourceware.org/ml/gdb-patches/2006-07/msg00392.html
>
> Mark, I don't suppose you find it convincing that the libgcc unwinder
> terminates on PC == 0 too?
It's a perfectly reasonable thing for the libgcc unwinder to do (just
as it is for us in GDB). But in a debugger I want to see that PC == 0
if it is an abnormal backtrace termination.
What really needs to be done is making the DWARF2 unwinder recognize the
condition and return a suitable frame id for that.
Mark