[PATCH v3 10/19] btrace: temporarily set inferior_ptid in record_btrace_start_replaying

Markus Metzger
2015-09-17T14:10:05Z

Get_current_frame uses inferior_ptid. In record_btrace_start_replaying,
we need to get the current frame of the argument thread. So far, this
has always been inferior_ptid. With non-stop, this is not guaranteed.

Temporarily set inferior_ptid to the ptid of the argument thread.

We already temporarily set the argument thread's executing flag to false.

Move both into a new function get_thread_current_frame that does the temporary
adjustments, calls get_current_frame, and restores the previous values.

2015-09-17 Markus Metzger <markus.t.metzger@intel.com>

gdb/
* record-btrace.c (get_thread_current_frame): New.
(record_btrace_start_replaying): Call get_thread_current_frame.
---
gdb/record-btrace.c | 70 ++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 51 insertions(+), 19 deletions(-)

diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index c25b8f4..0514471 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -1707,6 +1707,55 @@ record_btrace_resume_thread (struct thread_info *tp,
btinfo->flags |= flag;
}

+/* Get the current frame for TP. */
+
+static struct frame_info *
+get_thread_current_frame (struct thread_info *tp)
+{
+ struct frame_info *frame;
+ ptid_t old_inferior_ptid;
+ int executing;
+
+ /* Set INFERIOR_PTID, which is implicitly used by get_current_frame. */
+ old_inferior_ptid = inferior_ptid;
+ inferior_ptid = tp->ptid;
+
+ /* Clear the executing flag to allow changes to the current frame.
+ We are not actually running, yet. We just started a reverse execution
+ command or a record goto command.
+ For the latter, EXECUTING is false and this has no effect.
+ For the former, EXECUTING is true and we're in to_wait, about to
+ move the thread. Since we need to recompute the stack, we temporarily
+ set EXECUTING to flase. */
+ executing = is_executing (inferior_ptid);
+ set_executing (inferior_ptid, 0);
+
+ frame = NULL;
+ TRY
+ {
+ frame = get_current_frame ();
+ }
+ CATCH (except, RETURN_MASK_ALL)
+ {
+ /* Restore the previous execution state. */
+ set_executing (inferior_ptid, executing);
+
+ /* Restore the previous inferior_ptid. */
+ inferior_ptid = old_inferior_ptid;
+
+ throw_exception (except);
+ }
+ END_CATCH
+
+ /* Restore the previous execution state. */
+ set_executing (inferior_ptid, executing);
+
+ /* Restore the previous inferior_ptid. */
+ inferior_ptid = old_inferior_ptid;
+
+ return frame;
+}
+
/* Start replaying a thread. */

static struct btrace_insn_iterator *
@@ -1714,7 +1763,6 @@ record_btrace_start_replaying (struct thread_info *tp)
{
struct btrace_insn_iterator *replay;
struct btrace_thread_info *btinfo;
- int executing;

btinfo = &tp->btrace;
replay = NULL;
@@ -1723,16 +1771,6 @@ record_btrace_start_replaying (struct thread_info *tp)
if (btinfo->begin == NULL)
return NULL;

- /* Clear the executing flag to allow changes to the current frame.
- We are not actually running, yet. We just started a reverse execution
- command or a record goto command.
- For the latter, EXECUTING is false and this has no effect.
- For the former, EXECUTING is true and we're in to_wait, about to
- move the thread. Since we need to recompute the stack, we temporarily
- set EXECUTING to flase. */
- executing = is_executing (tp->ptid);
- set_executing (tp->ptid, 0);
-
/* GDB stores the current frame_id when stepping in order to detects steps
into subroutines.
Since frames are computed differently when we're replaying, we need to
@@ -1745,7 +1783,7 @@ record_btrace_start_replaying (struct thread_info *tp)
int upd_step_frame_id, upd_step_stack_frame_id;

/* The current frame without replaying - computed via normal unwind. */
- frame = get_current_frame ();
+ frame = get_thread_current_frame (tp);
frame_id = get_frame_id (frame);

/* Check if we need to update any stepping-related frame id's. */
@@ -1777,7 +1815,7 @@ record_btrace_start_replaying (struct thread_info *tp)
registers_changed_ptid (tp->ptid);

/* The current frame with replaying - computed via btrace unwind. */
- frame = get_current_frame ();
+ frame = get_thread_current_frame (tp);
frame_id = get_frame_id (frame);

/* Replace stepping related frames where necessary. */
@@ -1788,9 +1826,6 @@ record_btrace_start_replaying (struct thread_info *tp)
}
CATCH (except, RETURN_MASK_ALL)
{
- /* Restore the previous execution state. */
- set_executing (tp->ptid, executing);
-
xfree (btinfo->replay);
btinfo->replay = NULL;

@@ -1800,9 +1835,6 @@ record_btrace_start_replaying (struct thread_info *tp)
}
END_CATCH

- /* Restore the previous execution state. */
- set_executing (tp->ptid, executing);
-
return replay;
}

--
1.8.3.1