[RFA] Patch to fix reverse-debug recursion function tail bug
Hui Zhu
teawater@gmail.com
Mon Jun 15 03:37:00 GMT 2009
On Mon, Jun 15, 2009 at 08:55, Michael Snyder<msnyder@vmware.com> wrote:
> Hui Zhu wrote:
>>
>> PING
>
> Thanks for the reminder.
>
> I added some comment and changed the order of evaluation a bit,
> hoping to reduce the performance impact on normal debugging.
> And I ran the testsuites, before and after.
>
> Modified patch is attached -- is this OK with you guys?
> Mark, can you confirm that it fixes your original bug?
>
This patch is OK with me.
Marc, what do you think about it?
Thanks,
Hui
>
>
>> On Mon, May 11, 2009 at 15:07, Hui Zhu<teawater@gmail.com> wrote:
>>>
>>> PING
>>>
>>> On Wed, May 6, 2009 at 15:23, Hui Zhu <teawater@gmail.com> wrote:
>>>>
>>>> Hi Michael,
>>>>
>>>> Like the prev patch I send to you, this issue still affect cvs-head
>>>> and the patch can fix it.
>>>> 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): Check frame_id when
>>>> check range in reverse debug mode.
>>>>
>>>> Thanks,
>>>> Hui
>>>>
>>>> On Sat, Mar 21, 2009 at 16:52, Hui Zhu <teawater@gmail.com> wrote:
>>>>>
>>>>> Hi,
>>>>>
>>>>> This patch is for bug report by Marc in
>>>>> http://sourceware.org/ml/gdb/2009-03/msg00127.html.
>>>>>
>>>>> This bug in "handle_inferior_event" deal with recursion function tail
>>>>> in reverse debug.
>>>>> infrun: infwait_normal_state
>>>>> infrun: TARGET_WAITKIND_STOPPED
>>>>> infrun: stop_pc = 0x8048457
>>>>> infrun: stepping inside range [0x8048457-0x804845a]
>>>>> infrun: stop_stepping
>>>>> factorial (x=4) at b.cc:5
>>>>>
>>>>> Inferior already step into another frame. But because this is a
>>>>> recursion function call, And 0x8048457 is in
>>>>> ecs->event_thread->step_range_start and
>>>>> ecs->event_thread->step_range_start.
>>>>>
>>>>> So gdb run in:
>>>>>
>>>>> if (stop_pc >= ecs->event_thread->step_range_start
>>>>> && stop_pc < ecs->event_thread->step_range_end)
>>>>> {
>>>>>
>>>>> This code is in front of:
>>>>> if (!frame_id_eq (get_frame_id (get_current_frame ()),
>>>>> ecs->event_thread->step_frame_id)
>>>>> && (frame_id_eq (frame_unwind_id (get_current_frame ()),
>>>>> ecs->event_thread->step_frame_id)
>>>>> || execution_direction == EXEC_REVERSE))
>>>>>
>>>>> So gdb check range without check frame_id.
>>>>>
>>>>> So I make a patch to check frame_id when check range in reverse debug
>>>>> mode.
>>>>>
>>>>> 2008-03-21 Hui Zhu <teawater@gmail.com>
>>>>>
>>>>> * infrun.c (handle_inferior_event): Check frame_id when
>>>>> check range in reverse debug mode.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Actually, there is another thing, when gdb begin reverse-debug, it's
>>>>> range is:
>>>>> 8048439: 8b 45 08 mov 0x8(%ebp),%eax
>>>>> 804843c: 83 e8 01 sub $0x1,%eax
>>>>> 804843f: 89 04 24 mov %eax,(%esp)
>>>>> 8048442: e8 dd ff ff ff call 8048424 <_Z9factoriali>
>>>>> 8048447: 0f af 45 08 imul 0x8(%ebp),%eax
>>>>> 804844b: 89 45 fc mov %eax,-0x4(%ebp)
>>>>> Why is changed to infrun: stepping inside range [0x8048457-0x804845a]?
>>>>> That is because when inferior step at:
>>>>> 8048458: c3 ret
>>>>> In this address, $ebp is same with high level function and this
>>>>> function is factorial too.
>>>>> So the gdb can't found inferior step into another frame. It will run
>>>>> to:
>>>>> ecs->event_thread->step_range_start = stop_pc_sal.pc;
>>>>> ecs->event_thread->step_range_end = stop_pc_sal.end;
>>>>> ecs->event_thread->step_frame_id = get_frame_id (get_current_frame
>>>>> ());
>>>>> ecs->event_thread->current_line = stop_pc_sal.line;
>>>>> ecs->event_thread->current_symtab = stop_pc_sal.symtab;
>>>>>
>>>>> if (debug_infrun)
>>>>> fprintf_unfiltered (gdb_stdlog, "infrun: keep going\n");
>>>>> keep_going (ecs);
>>>>> }
>>>>> So ecs->event_thread->step_range_start and
>>>>> ecs->event_thread->step_range_end.
>>>>>
>>>>> I don't find that it affect the reverse debug or something. So I
>>>>> didn't fix it.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Thanks,
>>>>> Hui
>>>>>
>>
>>
>
>
> 2009-06-14 Hui Zhu <teawater@gmail.com>
> Michael Snyder <msnyder@vmware.com>
>
> * infrun.c (handle_inferior_event): Improve reverse stepping
> through function epilogue.
>
> 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 00:45:17 -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",
>
>
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