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

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

Andrew Cagney wrote:

>I'm lost here. What happens with:
> 
>- get_frame_id (get_prev_frame (signal handler))
>- get_frame_id (sigreturn trampoline)
> 
>They should match

Well, they do match, that's why things work with my patch.

The problem is that without my patch, step_over_function
doesn't actually *use* get_frame_id (get_prev_frame ...),
see the 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;
  else if (legacy_frame_p (current_gdbarch))
    /* NOTE: cagney/2004-02-27: This is the way it was 'cos this is
       the way it always was.  It should be using the unwound (or
       caller's) ID, and not this (or the callee's) ID.  It appeared
       to work because: legacy architectures used the wrong end of the
       frame for the ID.stack (inner-most rather than outer-most) so
       that the callee's id.stack (un adjusted) matched the caller's
       id.stack giving the "correct" id; more often than not
       !IN_SOLIB_DYNSYM_RESOLVE_CODE and hence the code above (it was
       originally later in the function) fixed the ID by using global
       state.  */
    sr_id = get_frame_id (get_current_frame ());
  else
    sr_id = get_frame_id (get_prev_frame (get_current_frame ()));

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.
 
Bye,
Ulrich

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