[PATCH v2 12/17] infrun: switch to NO_HISTORY thread

[Markus Metzger <markus dot t dot metzger at intel dot com>]

A thread that runs out of its execution history is stopped.  We already set
stop_pc and call stop_waiting.  But we do not switch to the stopped thread.

In normal_stop, we call finish_thread_state_cleanup to set a thread's running
state.  In all-stop mode, we call it with minus_one_ptid; in non-stop mode, we
only call it for inferior_ptid.

If in non-stop mode normal_stop is called on behalf of a thread that is not
inferior_ptid, that other thread will still be reported as running.  If it is
actually stopped it can't be resumed again.

Record targets traditionally don't support non-stop and only resume
inferior_ptid.  So this has not been a problem, so far.

Switch to the eventing thread for NO_HISTORY events as preparation to support
non-stop for the record btrace target.

2015-09-11  Markus Metzger <markus.t.metzger@intel.com>

gdb/
	* infrun.c (handle_inferior_event_1): Switch to the eventing thread
	in the TARKET_WAITKIND_NO_HISTORY case.
---
 gdb/infrun.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/gdb/infrun.c b/gdb/infrun.c
index e89e02a..c4a99d8 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -5095,8 +5095,14 @@ Cannot fill $_exitsignal with the correct signal number.\n"));
         fprintf_unfiltered (gdb_stdlog, "infrun: TARGET_WAITKIND_NO_HISTORY\n");
       /* Reverse execution: target ran out of history info.  */
 
+      /* Switch to the stopped thread.  */
+      if (!ptid_equal (ecs->ptid, inferior_ptid))
+	context_switch (ecs->ptid);
+      if (debug_infrun)
+	fprintf_unfiltered (gdb_stdlog, "infrun: stopped\n");
+
       delete_just_stopped_threads_single_step_breakpoints ();
-      stop_pc = regcache_read_pc (get_thread_regcache (ecs->ptid));
+      stop_pc = regcache_read_pc (get_thread_regcache (inferior_ptid));
       observer_notify_no_history ();
       stop_waiting (ecs);
       return;
-- 
1.8.3.1