Re: [PATCH] Fix signals.exp test case on S/390

[Ulrich Weigand <weigand@i1.informatik.uni-erlangen.de>]

Andrew Cagney wrote:
> > It will run into the first if, and simply use step_frame_id,
> > which is wrong in this case.  That's why my patch add another
> > condition to the first if, to make it not taken and actually
> > use the (correct) get_prev_frame case.
> 
> Where is step_frame_id pointing?

To the function that was interrupted by the signal (i.e. the
function where I entered 'next').

> Anyway, I think this code:
>  >   if (frame_id_p (step_frame_id)
>  >       && !IN_SOLIB_DYNSYM_RESOLVE_CODE (sr_sal.pc))
>  >     /* NOTE: cagney/2004-02-27: Use the global state's idea of the
>  >        stepping frame ID.  I suspect this is done as it is lighter
>  >        weight than a call to get_prev_frame.  */
>  >     sr_id = step_frame_id;
> should simply be deleted.  I wondered about it and you've just confirmed 
> my suspicions.  With that code gone is half the problem solved?

Yes, deleting this works just fine for me, in fact ...

> That leaves the other problem, which is much harder :-(

... it even solves the other problem as well!

The reason for this is that the whole problematic if 
that uses frame_id_inner becomes irrelevant:

      if (pc_in_sigtramp (stop_pc)
          && frame_id_inner (step_frame_id,
                             frame_id_build (read_sp (), 0)))
        /* We stepped out of a signal handler, and into its
           calling trampoline.  This is misdetected as a
           subroutine call, but stepping over the signal
           trampoline isn't such a bad idea.  In order to do that,
           we have to ignore the value in step_frame_id, since
           that doesn't represent the frame that'll reach when we
           return from the signal trampoline.  Otherwise we'll
           probably continue to the end of the program.  */
        step_frame_id = null_frame_id;

      step_over_function (ecs);

With those lines in step_over_function deleted, step_over_function
does not care about step_frame_id at all any more, and thus there
is no need to fiddle with step_frame_id here ...

> > Finally, the patch below reintroduces a pc_in_sigtramp
> > gdbarch callback to s390-tdep.c; I had thought this would
> > be no longer necessary when using the new frame code, but
> > apparently there's still other users ...
> 
> Yes, it shouldn't be needed.  get_frame_type == SIGTRAMP_FRAME is 
> sufficient.  work-in-progress.

Actually, when deleting the lines in step_over_function, it turns
out that I don't need pc_in_sigtramp any more ...

Summing up: after completely reverting my patch, and simply 
deleting those lines, I get a gdb that passes signals.exp
(and has no test suite regressions), and also handles stepping
out of a signal handler correctly.

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  weigand@informatik.uni-erlangen.de