Re: Abort backtrace when consecutive zero PCs?

[Daniel Jacobowitz <drow@false.org>]

On Wed, Sep 15, 2004 at 06:43:48PM -0400, Andrew Cagney wrote:
> >On Wed, Sep 15, 2004 at 01:34:21PM -0400, Andrew Cagney wrote:
> >
> >>>Hello,
> >>>
> >>>One backtrace infinite loop case I've noticed (especially on ia64) is 
> >>>where successive frames all have a zero PC.
> >>>
> >>>While we definitly need to allow a backtrace through a single zero PC 
> >>>(for a NULL pointer call - signull.exp) should we make GDB abort when 
> >>>two or more consecutive frames have a zero PC?
> >>>
> >>>(mumble something about a runtime option)
> >>>
> >>>thoughts?
> >
> >
> >I still think that you
> 
> me or we?  Do you have a pointer to the thread?

I think that I want it; it was a form of speech indicating it would
address this problem.  I swear it's in the archives but I can't find
the right thing to search for.

> > want to reject zero PC followed by a normal
> >(non-signal/dummy) frame, for exactly this reason...
> 
> That sounds like a NULL pointer function call, which is what signull.exp 
> is all about.

"followed" in the other direction.  If we unwind a normal frame, and
the next outer frame has a PC of zero, stop unwinding.  We briefly had
this check for "if the next frame is not the innermost frame" and that
broke the equivalent of signull.exp; I think I proposed this in follow
discussion to that.

-- 
Daniel Jacobowitz