Re: [RFA] Reverse Debugging, 3/5

[Michael Snyder <msnyder at vmware dot com>]

Joel Brobecker wrote:
> I had some comments, too, but Pedro made most of them.  Here are mine
> that don't overlap with his...
>
> > +      /* OK, we're just gonna keep stepping here.  */
>
> I would prefer if we kept slang out of the comments. Can we use
> "going to" instead?

Sure.


> > +      if (stop_func_sal.pc == stop_pc)
> > +     {
> > +       /* We're there already.  Just stop stepping now.  */
> > +       ecs->event_thread->stop_step = 1;
> > +       print_stop_reason (END_STEPPING_RANGE, 0);
> > +       stop_stepping (ecs);
> > +       return;
> > +     }
> > +      /* Else just reset the step range and keep going.
> > +      No step-resume breakpoint, they don't work for
> > +      epilogues, which can have multiple entry paths.  */
> > +      ecs->event_thread->step_range_start = stop_func_sal.pc;
> > +      ecs->event_thread->step_range_end   = stop_func_sal.end;
> > +      keep_going (ecs);
> > +      return;
> > +    }>
> Regarding this hunk, it really took me a long time to understand
> what we're supposed to do when execution is reverse.  I think it
> was a combination of the function name together with the fact that
> we're not trying to undo what the function does, but instead implement
> whatever command the user has issued which caused us to call this
> function. I am thinking, for the sake of clarity, to implement this
> in a separate function and call the appropriate function from
> handle_inferior_event.  The function name can then be used to explain
> at a glance what it's supposed to do...

You lost me.  You're right, of course, it's quite difficult
to follow the flow of control here (it's infrun, what can I
say?).  The damn thing's a state machine, you know...
But I didn't follow exactly what you're saying here.

On the one hand, this function ("step_into_function") is
called from only one place (for now), so it wouldn't be too
difficult for me to test exec_direction BEFORE calling it
(and branch off to a different "step_backwards_into_function").

But on the other hand, this is exactly what we are doing here.
We are stepping into a function.  Only we're doing it in
reverse, so we're coming in thru a return, not thru a call.

You still think I should split them up?