Re: [RFA] Patch to fix "reverse-next" command error

Hui Zhu
2009-06-15T06:47:16Z

On Mon, Jun 15, 2009 at 10:45, Michael Snyder<msnyder@vmware.com> wrote:
> Hui Zhu wrote:
>>
>> Ping.
>
> Hui, I rewrote your patch a little bit.  I think we can use
> gdbarch_skip_trampoline_code to detect the fact that we have
> stepped into a trampoline (ie. "plt").  This is more general.
>
> Mark, please tell me if this patch fixes your original problem,
> and Hui, please tell me if the patch is OK with you.
>

This patch is OK with me.

BTW, the patch that you sent include the prev one.

Thanks,
Hui

>> On Mon, May 11, 2009 at 15:07, Hui Zhu<teawater@gmail.com> wrote:
>>>
>>> PING
>>>
>>> On Wed, May 6, 2009 at 14:00, Hui Zhu <teawater@gmail.com> wrote:
>>>>
>>>> Hi Michael,
>>>>
>>>> I try this issue with cvs-head.  It still affect cvs-head.
>>>> And I try the patch, it can fix this issue.  It's time close to 7.0
>>>> branch.  So could you please help me review it?
>>>>
>>>> The attachment is the new patch follow cvs-head.
>>>>
>>>> 2009-05-06  Hui Zhu  <teawater@gmail.com>
>>>>
>>>>      * infrun.c (handle_inferior_event): Make inferior step if it
>>>>      stepping over a function call in reverse , and stop at the
>>>>      start address of the function.
>>>>
>>>> Thanks,
>>>> Hui
>>>>
>>>> On Thu, Jan 22, 2009 at 17:00, teawater <teawater@gmail.com> wrote:
>>>>>
>>>>> Hi guys,
>>>>>
>>>>> This patch is for bug in
>>>>> http://sourceware.org/ml/gdb/2009-01/msg00146.html
>>>>>
>>>>> This issue is because sometime the inferior is already in function
>>>>> start address (i.e. plt), set a breakpoint and continue will make
>>>>> "reverse-next" work error.
>>>>>
>>>>> This patch make inferior step if it reverse step and stop at the
>>>>> function start address.
>>>>> It tested OK with process record patch and testsuite gdb.twreverse in
>>>>> branch reverse-20081226-branch.
>>>>>
>>>>> 2009-01-22  Hui Zhu  <teawater@gmail.com>
>>>>>
>>>>>       * infrun.c (handle_inferior_event): Make inferior step if it
>>>>>       stepping over a function call in reverse , and stop at the
>>>>>       start address of the function.
>>>>>
>>>>> OK for mainline?
>>>>>
>>>>> Thanks,
>>>>> Hui
>>>>>
>>
>
>
> 2009-06-14  Hui Zhu  <teawater@gmail.com>
>            Michael Snyder  <msnyder@vmware.com>
>
>        * infrun.c (handle_inferior_event): Reverse-next through trampoline.
>
> Index: infrun.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/infrun.c,v
> retrieving revision 1.387
> diff -u -p -r1.387 infrun.c
> --- infrun.c    11 Jun 2009 11:57:46 -0000      1.387
> +++ infrun.c    15 Jun 2009 02:39:51 -0000
> @@ -3623,9 +3623,17 @@ infrun: not switching back to stepped th
>
>      Note that step_range_end is the address of the first instruction
>      beyond the step range, and NOT the address of the last instruction
> -     within it! */
> +     within it!
> +
> +     Note also that during reverse execution, we may be stepping
> +     through a function epilogue and therefore must detect when
> +     the current-frame changes in the middle of a line.  */
> +
>   if (stop_pc >= ecs->event_thread->step_range_start
> -      && stop_pc < ecs->event_thread->step_range_end)
> +      && stop_pc < ecs->event_thread->step_range_end
> +      && (execution_direction != EXEC_REVERSE
> +         || frame_id_eq (get_frame_id (get_current_frame ()),
> +                         ecs->event_thread->step_frame_id)))
>     {
>       if (debug_infrun)
>        fprintf_unfiltered (gdb_stdlog, "infrun: stepping inside range
> [0x%s-0x%s]\n",
> @@ -3762,10 +3770,21 @@ infrun: not switching back to stepped th
>                  keep_going (ecs);
>                  return;
>                }
> -             /* Normal (staticly linked) function call return.  */
> -             init_sal (&sr_sal);
> -             sr_sal.pc = ecs->stop_func_start;
> -             insert_step_resume_breakpoint_at_sal (sr_sal, null_frame_id);
> +             if (gdbarch_skip_trampoline_code(current_gdbarch,
> +                                              get_current_frame (),
> +                                              stop_pc))
> +               {
> +                 /* We are in a function call trampoline.
> +                    Keep stepping backward to get to the caller.  */
> +                 ecs->event_thread->stepping_over_breakpoint = 1;
> +               }
> +             else
> +               {
> +                 /* Normal function call return (static or dynamic).  */
> +                 init_sal (&sr_sal);
> +                 sr_sal.pc = ecs->stop_func_start;
> +                 insert_step_resume_breakpoint_at_sal (sr_sal,
> null_frame_id);
> +               }
>            }
>          else
>            insert_step_resume_breakpoint_at_caller (get_current_frame ());
>
>