Re: [patch, rfc, 6?] Enable identical frame sanity check

[Daniel Jacobowitz <drow@mvista.com>]

On Thu, Jul 03, 2003 at 11:27:31AM -0400, Andrew Cagney wrote:
> >On Wed, Jul 02, 2003 at 02:27:39PM -0400, Andrew Cagney wrote:
> >
> >>Hello,
> >>
> >>This patch enables the `is the prev frame identical to this frame' check 
> >>in get_prev_frame().  I forgot to enable it when I switched the frame ID 
> >>code from using the frame's PC to using the frame's function.  Noticed 
> >>this when reviewing Daniel's Arm frame update.
> >>
> >>It should probably go straight into the mainline (tested on i386 and 
> >>d10v).
> >
> >
> >d10v, AVR, and soon ARM all include this check as a silent stop
> >condition rather than an error... perhaps that has some significance.
> 
> Ulgh! `prior art' :-)
> 
> >I know it's hit at least on ARM.
> 
> It hit the d10v as well, I'd have not otherwize added the test.
> 
> >I'd have to dumb down the prologue
> >analyzer if I wanted it not to be, or else figure out where an
> >inside_entry_func check has gone completely missing in the new frame
> >code.  Just putting it unwind_this_id didn't work (don't remember why
> >not).
> 
> Sounds like it should be treated like the stack bottom?
> 
> The other choice is to treat it as undefined and accept the warning.

Both make sense to me.  Probably the warning is better.  I think we
should figure out why inside_entry_func isn't stopping the backtrace
before this even becomes an issue, though...

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer