Re: [RFA] Reverse Debugging, 4/5

Michael Snyder
2008-10-06T21:50:50Z

Pedro Alves wrote:
> On Wednesday 01 October 2008 20:19:28, Michael Snyder wrote:
>> +static void finish_backwards (struct symbol *, struct thread_info *);
>> +
>
> Minor nit. If you put the new function here, you don't
> need the forward declaration.

OK.

>> function = find_pc_function (get_frame_pc (get_selected_frame (NULL)));
>> @@ -1427,10 +1422,29 @@ finish_command (char *arg, int from_tty)
>> source. */
>> if (from_tty)
>> {
>> - printf_filtered (_("Run till exit from "));
>> + if (target_get_execution_direction () == EXEC_REVERSE)
>> + printf_filtered ("Run back to call of ");
>> + else
>> + printf_filtered ("Run till exit from ");
>> +
>> print_stack_frame (get_selected_frame (NULL), 1, LOCATION);
>> }
>
> i18n.

OK.

>> +
>> +static void
>> +finish_backwards (struct symbol *function, struct thread_info *tp)
>> +{
>> + struct symtab_and_line sal;
>> + struct breakpoint *breakpoint;
>> + struct cleanup *old_chain;
>> + CORE_ADDR func_addr;
>> + int back_up;
>> +
>> + if (find_pc_partial_function (get_frame_pc (get_current_frame ()),
>> + NULL, &func_addr, NULL) == 0)
>> + internal_error (__FILE__, __LINE__,
>> + "Finish: couldn't find function.");
>
> Can't this happen in some circunstances, like the user hitting
> finish after stepi through
> no-debug-info-at-all-not-even-minimal-symbols code?

Ummmm... maybe. Probably, I suppose.
There are certainly circumstances where finish doesn't work
in the forward direction...

>
>> +
>> + sal = find_pc_line (func_addr, 0);
>> +
>> + /* TODO: Let's not worry about async until later. */
>
> If you don't want to think about it now, could you error out
> in the async+reverse case ?

Good idea.

>> +
>> + /* We don't need a return value. */
>> + tp->proceed_to_finish = 0;
>> + /* Special case: if we're sitting at the function entry point,
>> + then all we need to do is take a reverse singlestep. We
>> + don't need to set a breakpoint, and indeed it would do us
>> + no good to do so.
>> +
>> + Note that this can only happen at frame #0, since there's
>> + no way that a function up the stack can have a return address
>> + that's equal to its entry point. */
>> +
>> + if (sal.pc != read_pc ())
>> + {
>> + /* Set breakpoint and continue. */
>> + breakpoint =
>> + set_momentary_breakpoint (sal,
>> + get_frame_id (get_selected_frame (NULL)),
>> + bp_breakpoint);
>> + /* Tell the breakpoint to keep quiet. We won't be done
>> + until we've done another reverse single-step. */
>> + breakpoint_silence (breakpoint);
>> + old_chain = make_cleanup_delete_breakpoint (breakpoint);
>> + proceed ((CORE_ADDR) -1, TARGET_SIGNAL_DEFAULT, 0);
>> + /* We will be stopped when proceed returns. */
>> + back_up = bpstat_find_breakpoint (tp->stop_bpstat, breakpoint) != NULL;
>> + do_cleanups (old_chain);
>> + }
>> + else
>> + back_up = 1;
>> + if (back_up)
>> + {
>> + /* If in fact we hit the step-resume breakpoint (and not
>> + some other breakpoint), then we're almost there --
>> + we just need to back up by one more single-step. */
>> + /* (Kludgy way of letting wait_for_inferior know...) */
>> + tp->step_range_start = tp->step_range_end = 1;
>> + proceed ((CORE_ADDR) -1, TARGET_SIGNAL_DEFAULT, 1);
>
> Would calling step_1 or step_once instead work here? It would
> probably avoid the kludge.

I'll have to get back to you on that.

Thanks for the comments.