Re: [7.5] PATCH: PR backtrace/14646 [x32] backtrace doesn't work

[Mark Kettenis <mark dot kettenis at xs4all dot nl>]

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> Date: Fri, 09 Nov 2012 00:15:41 +0000
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> 
> On 10/21/2012 02:56 AM, Joel Brobecker wrote:
> >> This patch backports the fix from trunk to 7.5 branch.  Tested on
> >> Linux/x86-64 and Linux/x32.  OK to install?
> > [...]
> >> 	PR backtrace/14646
> >> 	PR gdb/14647
> >> 	* i386-tdep.h (gdbarch_tdep): Remove sp_regnum_from_eax and
> >> 	pc_regnum_from_eax.
> >> 	* i386-tdep.c (i386_gdbarch_init): Don't use sp_regnum_from_eax
> >> 	nor pc_regnum_from_eax.
> >> 	* amd64-tdep.c (amd64_x32_init_abi): Don't set sp_regnum_from_eax
> >> 	nor pc_regnum_from_eax.
> > 
> > I'm sorry to say that I am not comfortable at all with this going
> > in the 7.5 branch. If Mark is super confident, then OK, but this is
> > touching sp/pc handling for all x86 and x86-64 targets. And I don't
> > think that the issue this patch is fixing is that critical.
> 
> I'm not Mark, but it looks safe on all x86 and x86-64 targets to me.
> Note how tdep->sp_regnum_from_eax and tdep->sp_regnum_from_eax are -1
> by default, and only x32 sets it to something else.  Then, the only use
> for those fields:
> 
> -      if (tdep->sp_regnum_from_eax != -1)
> -	set_gdbarch_sp_regnum (gdbarch,
> -			       (tdep->eax_regnum
> -				+ tdep->sp_regnum_from_eax));
> -      if (tdep->pc_regnum_from_eax != -1)
> -	set_gdbarch_pc_regnum (gdbarch,
> -			       (tdep->eax_regnum
> -				+ tdep->pc_regnum_from_eax));
> 
> only had effect on x32.

Yeah, it's pretty safe.  Must say that I don't see the urgency as x32
is still in its infancy.