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Re: [RFA] Patch to fix reverse-debug recursion function tail bug


PING

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
>>>
>>
>


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