Re: [RFA] improved handling of shared lib calls (reverse 2/2)

[Hui Zhu <teawater at gmail dot com>]

On Wed, Jul 15, 2009 at 16:33, Hui Zhu<teawater@gmail.com> wrote:
> I try this patch with cvs-head and program:
> void foo() {
> ? ?return;
> }
>
> int main() {
>
> ? ? ? ?foo(); // 1
> ? ? ? ?foo(); // 2
> ? ? ? ?foo(); // 3
>
> ? ? ? ?return 0;
> }
> in ubuntu i386.
> And test with reverse testsuite.
> Everything is OK.
>
> Thanks,
> Hui
>
>
> On Wed, Jul 15, 2009 at 09:08, Michael Snyder<msnyder@vmware.com> wrote:
>> And now this one?
>>
>> Michael Snyder wrote:
>>>
>>> Now how about this one?
>>>
>>> Michael Snyder wrote:
>>>>
>>>> This change depends on the previous one (epilogue unwinder for i386,
>>>> http://sourceware.org/ml/gdb-patches/2009-07/msg00099.html).
>>>>
>>>> With the frame unwinder working properly, we can remove the
>>>> special case code in the test for "check for subroutine call"
>>>> in handle_inferior_event.
>>>>
>>>> Of course that reveals some hidden problems with shared library
>>>> calls, so this patch also addresses those.
>>>>
>>>> Michael
>>>>
>>>>
>>>>
>>>> ------------------------------------------------------------------------
>>>>
>>>> 2009-07-03 ?Michael Snyder ?<msnyder@vmware.com>
>>>>
>>>> ? ? ? ?* infrun.c (handle_inferior_event): Remove an execution_direction
>>>> ? ? ? ?check in the "check for subroutine calls" test, and add some
>>>> ?additional handling for reverse-stepping through shared libraries.
>>>>
>>>> Index: infrun.c
>>>> ===================================================================
>>>> RCS file: /cvs/src/src/gdb/infrun.c,v
>>>> retrieving revision 1.400
>>>> diff -u -p -r1.400 infrun.c
>>>> --- infrun.c ? ?2 Jul 2009 17:21:06 -0000 ? ? ? 1.400
>>>> +++ infrun.c ? ?4 Jul 2009 00:27:53 -0000
>>>> @@ -3776,9 +3776,8 @@ infrun: not switching back to stepped th
>>>> ? ? ?previous frame must have valid frame IDs. ?*/
>>>> ? if (!frame_id_eq (get_stack_frame_id (frame),
>>>> ? ? ? ? ? ? ? ? ? ?ecs->event_thread->step_stack_frame_id)
>>>> - ? ? ?&& (frame_id_eq (frame_unwind_caller_id (frame),
>>>> - ? ? ? ? ? ? ? ? ? ? ?ecs->event_thread->step_stack_frame_id)
>>>> - ? ? ? ? || execution_direction == EXEC_REVERSE))
>>>> + ? ? ?&& frame_id_eq (frame_unwind_caller_id (frame),
>>>> + ? ? ? ? ? ? ? ? ? ? ecs->event_thread->step_stack_frame_id))
>>>> ? ? {
>>>> ? ? ? CORE_ADDR real_stop_pc;
>>>> ?@@ -3806,6 +3805,7 @@ infrun: not switching back to stepped th
>>>> ? ? ? /* Reverse stepping through solib trampolines. ?*/
>>>> ? ? ? ? if (execution_direction == EXEC_REVERSE
>>>> + ? ? ? ? && ecs->event_thread->step_over_calls != STEP_OVER_NONE
>>>> ? ? ? ? ?&& (gdbarch_skip_trampoline_code (gdbarch, frame, stop_pc)
>>>> ? ? ? ? ? ? ?|| (ecs->stop_func_start == 0
>>>> ? ? ? ? ? ? ? ? ?&& in_solib_dynsym_resolve_code (stop_pc))))
>>>> @@ -3923,6 +3923,38 @@ infrun: not switching back to stepped th
>>>> ? ? ? return;
>>>> ? ? }
>>>> ?+ ?/* Reverse stepping through solib trampolines. ?*/
>>>> +
>>>> + ?if (execution_direction == EXEC_REVERSE
>>>> + ? ? ?&& ecs->event_thread->step_over_calls != STEP_OVER_NONE)
>>>> + ? ?{
>>>> + ? ? ?if (gdbarch_skip_trampoline_code (gdbarch, frame, stop_pc)
>>>> + ? ? ? ? || (ecs->stop_func_start == 0
>>>> + ? ? ? ? ? ? && in_solib_dynsym_resolve_code (stop_pc)))
>>>> + ? ? ? {
>>>> + ? ? ? ? /* Any solib trampoline code can be handled in reverse
>>>> + ? ? ? ? ? ?by simply continuing to single-step. ?We have already
>>>> + ? ? ? ? ? ?executed the solib function (backwards), and a few +
>>>> ? ?steps will take us back through the trampoline to the
>>>> + ? ? ? ? ? ?caller. ?*/
>>>> + ? ? ? ? keep_going (ecs);
>>>> + ? ? ? ? return;
>>>> + ? ? ? }
>>>> + ? ? ?else if (in_solib_dynsym_resolve_code (stop_pc))
>>>> + ? ? ? {
>>>> + ? ? ? ? /* Stepped backward into the solib dynsym resolver.
>>>> + ? ? ? ? ? ?Set a breakpoint at its start and continue, then
>>>> + ? ? ? ? ? ?one more step will take us out. ?*/
>>>> + ? ? ? ? struct symtab_and_line sr_sal;
>>>> + ? ? ? ? init_sal (&sr_sal);
>>>> + ? ? ? ? sr_sal.pc = ecs->stop_func_start;
>>>> + ? ? ? ? insert_step_resume_breakpoint_at_sal (gdbarch, +
>>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? sr_sal, null_frame_id);
>>>> + ? ? ? ? keep_going (ecs);
>>>> + ? ? ? ? return;
>>>> + ? ? ? }
>>>> + ? ?}
>>>> +
>>>> ? /* If we're in the return path from a shared library trampoline,
>>>> ? ? ?we want to proceed through the trampoline when stepping. ?*/
>>>> ? if (gdbarch_in_solib_return_trampoline (gdbarch,
>>>
>>>
>>
>>
>

In AMD64,  This patch cannot pass the "solib-reverse.exp" even if with
the "set_gdbarch_skip_trampoline_code (gdbarch,
find_solib_trampoline_target);" patch.
And cannot pass the:
void foo() {
   return;
}

int main() {

       foo(); // 1
       foo(); // 2
       foo(); // 3

       return 0;
}

I told that we can make " Add step_stack_prev_frame_id" patch together
with this patch.
I make update the patch.  It can handle the solib-reverse.exp and foo.
 I think it let us don't worry about the arch code.

What do you think about it?

Thanks,
Hui

2009-07-16  Michael Snyder  <msnyder@vmware.com>
            Hui Zhu  <teawater@gmail.com>

	* gdbthread.h (thread_info): Add step_stack_prev_frame_id to
	save the prev_frame_id when we can get the prev_frame.
	* infrun.c (inferior_status): Ditto.
	(save_inferior_status): Ditto.
	(restore_inferior_status): Ditto.
	(set_step_info): Get the step_stack_prev_frame_id.
	(handle_inferior_event): Use the step_stack_prev_frame_id make
	sure inferior stepped into subroutine or not.  Add some
	additional handling for reverse-stepping through shared
	libraries.

---
 gdbthread.h |    3 +++
 infrun.c    |   49 +++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 50 insertions(+), 2 deletions(-)

--- a/gdbthread.h
+++ b/gdbthread.h
@@ -88,6 +88,9 @@ struct thread_info
      any inlined frames).  */
   struct frame_id step_stack_frame_id;

+  /* The prev frame id of step_stack_frame_id.  */
+  struct frame_id step_stack_prev_frame_id;
+
   int current_line;
   struct symtab *current_symtab;

--- a/infrun.c
+++ b/infrun.c
@@ -2153,10 +2153,17 @@ void
 set_step_info (struct frame_info *frame, struct symtab_and_line sal)
 {
   struct thread_info *tp = inferior_thread ();
+  struct frame_info *prev_frame;

   tp->step_frame_id = get_frame_id (frame);
   tp->step_stack_frame_id = get_stack_frame_id (frame);

+  prev_frame = get_prev_frame (frame);
+  if (prev_frame)
+    tp->step_stack_prev_frame_id = get_stack_frame_id (prev_frame);
+  else
+    tp->step_stack_prev_frame_id = null_frame_id;
+
   tp->current_symtab = sal.symtab;
   tp->current_line = sal.line;
 }
@@ -3777,8 +3784,10 @@ infrun: not switching back to stepped th
   if (!frame_id_eq (get_stack_frame_id (frame),
 		    ecs->event_thread->step_stack_frame_id)
       && (frame_id_eq (frame_unwind_caller_id (frame),
-		       ecs->event_thread->step_stack_frame_id)
-	  || execution_direction == EXEC_REVERSE))
+		      ecs->event_thread->step_stack_frame_id)
+	  || (execution_direction == EXEC_REVERSE
+               && !frame_id_eq (get_stack_frame_id (frame),
+                                ecs->event_thread->step_stack_prev_frame_id))))
     {
       CORE_ADDR real_stop_pc;

@@ -3806,6 +3815,7 @@ infrun: not switching back to stepped th
       /* Reverse stepping through solib trampolines.  */

       if (execution_direction == EXEC_REVERSE
+	  && ecs->event_thread->step_over_calls != STEP_OVER_NONE
 	  && (gdbarch_skip_trampoline_code (gdbarch, frame, stop_pc)
 	      || (ecs->stop_func_start == 0
 		  && in_solib_dynsym_resolve_code (stop_pc))))
@@ -3923,6 +3933,38 @@ infrun: not switching back to stepped th
       return;
     }

+  /* Reverse stepping through solib trampolines.  */
+
+  if (execution_direction == EXEC_REVERSE
+      && ecs->event_thread->step_over_calls != STEP_OVER_NONE)
+    {
+      if (gdbarch_skip_trampoline_code (gdbarch, frame, stop_pc)
+	  || (ecs->stop_func_start == 0
+	      && in_solib_dynsym_resolve_code (stop_pc)))
+	{
+	  /* Any solib trampoline code can be handled in reverse
+	     by simply continuing to single-step.  We have already
+	     executed the solib function (backwards), and a few
+	     steps will take us back through the trampoline to the
+	     caller.  */
+	  keep_going (ecs);
+	  return;
+	}
+      else if (in_solib_dynsym_resolve_code (stop_pc))
+	{
+	  /* Stepped backward into the solib dynsym resolver.
+	     Set a breakpoint at its start and continue, then
+	     one more step will take us out.  */
+	  struct symtab_and_line sr_sal;
+	  init_sal (&sr_sal);
+	  sr_sal.pc = ecs->stop_func_start;
+	  insert_step_resume_breakpoint_at_sal (gdbarch,
+						sr_sal, null_frame_id);
+	  keep_going (ecs);
+	  return;
+	}
+    }
+
   /* If we're in the return path from a shared library trampoline,
      we want to proceed through the trampoline when stepping.  */
   if (gdbarch_in_solib_return_trampoline (gdbarch,
@@ -5388,6 +5430,7 @@ struct inferior_status
   CORE_ADDR step_range_end;
   struct frame_id step_frame_id;
   struct frame_id step_stack_frame_id;
+  struct frame_id step_stack_prev_frame_id;
   enum step_over_calls_kind step_over_calls;
   CORE_ADDR step_resume_break_address;
   int stop_after_trap;
@@ -5418,6 +5461,7 @@ save_inferior_status (void)
   inf_status->step_range_end = tp->step_range_end;
   inf_status->step_frame_id = tp->step_frame_id;
   inf_status->step_stack_frame_id = tp->step_stack_frame_id;
+  inf_status->step_stack_prev_frame_id = tp->step_stack_prev_frame_id;
   inf_status->step_over_calls = tp->step_over_calls;
   inf_status->stop_after_trap = stop_after_trap;
   inf_status->stop_soon = inf->stop_soon;
@@ -5472,6 +5516,7 @@ restore_inferior_status (struct inferior
   tp->step_range_end = inf_status->step_range_end;
   tp->step_frame_id = inf_status->step_frame_id;
   tp->step_stack_frame_id = inf_status->step_stack_frame_id;
+  tp->step_stack_prev_frame_id = inf_status->step_stack_prev_frame_id;
   tp->step_over_calls = inf_status->step_over_calls;
   stop_after_trap = inf_status->stop_after_trap;
   inf->stop_soon = inf_status->stop_soon;

Attachment: solib.txt
Description: Text document