Re: [PATCH v2 2/3] frame: use get_prev_frame_always in skip_tailcall_frames

[Pedro Alves <palves@redhat.com>]

On 02/15/2016 09:50 AM, Metzger, Markus T wrote:

> I'm wondering in which cases GDB should ignore the user-defined backtrace
> limit.  And if GDB should ignore it at all.
> 
> If the limit is set, some aspects of GDB may not function any longer.  But that's
> to be expected, isn't it?
> 
> GDB shouldn't crash, of course.  But I'm not sure if it should ignore user settings
> in too many cases.  

I'm starting to think the same way.  Want to give it a try and see what breaks?

> Maybe we should even switch back to get_prev_frame in
> skip_artificial_frames and rely on handling the NULL return if we exceed the
> backtrace limit?

If all places will end up throwing an error, it may be the better to
make skip_artificial_frames itself throw.  We'd have to take a deeper look at each
case though.

We need to also keep in mind that there may be cases where skip_artificial_frames might
be used in internal-facing code, where it might still be necessary get past inline
frames to reach the real stack frame.  I guess sticking a "set backtrace limit 1" in
some of the inline tests would expose this.

Thanks,
Pedro Alves