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Re: GDB 6.2 for ARM: bug in backtrace when in Thumb mode
- From: Thierry <goldy_gnu at yahoo dot com>
- To: Richard Earnshaw <rearnsha at gcc dot gnu dot org>
- Cc: gdb at sources dot redhat dot com
- Date: Tue, 7 Sep 2004 05:55:55 -0700 (PDT)
- Subject: Re: GDB 6.2 for ARM: bug in backtrace when in Thumb mode
No, indeed, it wasn't (I'm working with gcc 3.4).
I'll wait for gcc 3.5, then!
Thank you Richard.
--- Richard Earnshaw <rearnsha@gcc.gnu.org> wrote:
> On Tue, 2004-09-07 at 13:02, Thierry wrote:
> > Hi there,
> >
> > I'm trying to debug an application compiled for the
> > ARM in Thumb mode. The 'backtrace' command seems buggy
> > as soon as there are more than 4 levels in the stack.
> > Besides, with the same code compiled in ARM mode, it
> > works perfectly.
> >
> > Here's an example:
> >
> > void dummy2(int a)
> > {
> > int b;
> > b = a;
> > }
> >
> > void dummy1(void)
> > {
> > dummy2(4);
> > }
> >
> > void dummy(void)
> > {
> > dummy1();
> > }
> >
> > In my 'main', I call 'dummy()'.
> >
> > When I go step-by-step until I step into 'dummy2', the
> > 'bt' command gives the following result:
> > #0 dummy2 (a=4) at MainModule/src/dummy.c:4
> > #1 0xc000039c in dummy1 () at
> > MainModule/src/dummy.c:9
> > #2 0x00000000 in ?? ()
> >
> > which is wrong!
> >
> > The files have been compiled with arm-elf-gcc with the
> > following options:
> > -ggdb -gdwarf-2 -c -mapcs -fomit-frame-pointer -mthumb
> > -mthumb-interwork -mlong-calls
> > -fsigned-char -mstructure-size-boundary=8
> > -fshort-enums
> >
> > When I remove the option '-fomit-frame-pointer', it
> > works.
> >
> > Any idea?
> >
>
> Most (all?) Released versions of gcc don't generate unwind information
> for Thumb functions, so the unwinder gets confused if there's no frame
> pointer.
>
> It will be fixed in gcc-3.5, but I don't think it was fixed in time for
> gcc-3.4.
>
> R.
>
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