Add method/format information to =record-started

Eclipse CDT now supports enabling execution recording using two methods
(full and btrace) and both formats for btrace (bts and pt).  In the
event that recording is enabled behind the back of the GUI (by the user
on the command line, or a script), we need to know which method/format
are being used, so it can be correctly reflected in the interface.  This
patch adds this information to the =record-started async record.

Before:

  =record-started,thread-group="i1"

After:

  =record-started,thread-group="i1",method="btrace",format="bts"
  =record-started,thread-group="i1",method="btrace",format="pt"
  =record-started,thread-group="i1",method="full"

The "format" field is only present when the current method supports
multiple formats (only the btrace method as of now).

gdb/ChangeLog:

	* NEWS: Mention the new fields in =record-started.
	* common/btrace-common.h (btrace_format_short_string): New function
	declaration.
	* common/btrace-common.c (btrace_format_short_string): New
	function.
	* mi/mi-interp.c (mi_record_changed): Output method and format
	fields in the =record-started record.
	* record-btrace.c (record_btrace_open): Adapt record_changed
	notification.
	* record-full.c (record_full_open): Likewise.
	* record.c (cmd_record_stop): Likewise.

gdb/doc/ChangeLog:

	* gdb.texinfo (GDB/MI Async Records): Document method and
	format fields in =record-started.
	* observer.texi (record_changed): Add method and format
	parameters.

gdb/testsuite/ChangeLog:

	* gdb.mi/mi-record-changed.exp: Adjust =record-started output
	matching.

13 files changed, 94 insertions, 11 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index af4ddcc..01cc770 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,17 @@
+2016-06-06  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* NEWS: Mention the new fields in =record-started.
+	* common/btrace-common.h (btrace_format_short_string): New function
+	declaration.
+	* common/btrace-common.c (btrace_format_short_string): New
+	function.
+	* mi/mi-interp.c (mi_record_changed): Output method and format
+	fields in the =record-started record.
+	* record-btrace.c (record_btrace_open): Adapt record_changed
+	notification.
+	* record-full.c (record_full_open): Likewise.
+	* record.c (cmd_record_stop): Likewise.
+
 2016-06-02  Jon Turney  <jon.turney@dronecode.org.uk>
 
 	* windows-nat.c (handle_output_debug_string): Return type of
diff --git a/gdb/NEWS b/gdb/NEWS
index dce79a2..253c8e5 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -67,6 +67,11 @@ maint selftest
   including JIT compiling fast tracepoint's conditional expression
   bytecode into native code.
 
+* MI async record =record-started now includes the method and format used for
+  recording.  For example:
+
+    =record-started,thread-group="i1",method="btrace",format="bts"
+
 *** Changes in GDB 7.11
 
 * GDB now supports debugging kernel-based threads on FreeBSD.
diff --git a/gdb/common/btrace-common.c b/gdb/common/btrace-common.c
index eba3979..90aef76 100644
--- a/gdb/common/btrace-common.c
+++ b/gdb/common/btrace-common.c
@@ -43,6 +43,26 @@ btrace_format_string (enum btrace_format format)
 
 /* See btrace-common.h.  */
 
+const char *
+btrace_format_short_string (enum btrace_format format)
+{
+  switch (format)
+    {
+    case BTRACE_FORMAT_NONE:
+      return "unknown";
+
+    case BTRACE_FORMAT_BTS:
+      return "bts";
+
+    case BTRACE_FORMAT_PT:
+      return "pt";
+    }
+
+  internal_error (__FILE__, __LINE__, _("Unknown branch trace format"));
+}
+
+/* See btrace-common.h.  */
+
 void
 btrace_data_init (struct btrace_data *data)
 {
diff --git a/gdb/common/btrace-common.h b/gdb/common/btrace-common.h
index ad208cd..d702bb8 100644
--- a/gdb/common/btrace-common.h
+++ b/gdb/common/btrace-common.h
@@ -214,6 +214,9 @@ enum btrace_error
 /* Return a string representation of FORMAT.  */
 extern const char *btrace_format_string (enum btrace_format format);
 
+/* Return an abbreviation string representation of FORMAT.  */
+extern const char *btrace_format_short_string (enum btrace_format format);
+
 /* Initialize DATA.  */
 extern void btrace_data_init (struct btrace_data *data);
 
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 9ed044b..8ef6cba 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,10 @@
+2016-06-06  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* gdb.texinfo (GDB/MI Async Records): Document method and
+	format fields in =record-started.
+	* observer.texi (record_changed): Add method and format
+	parameters.
+
 2016-05-27  Eli Zaretskii  <eliz@gnu.org>
 
 	* gdb.texinfo (General Query Packets): Move the description of the
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 7e89003..1da81a1 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -26423,12 +26423,17 @@ breakpoint commands; @xref{GDB/MI Breakpoint Commands}.  The
 Note that if a breakpoint is emitted in the result record of a
 command, then it will not also be emitted in an async record.
 
-@item =record-started,thread-group="@var{id}"
+@item =record-started,thread-group="@var{id}",method="@var{method}"[,format="@var{format}"]
 @itemx =record-stopped,thread-group="@var{id}"
 Execution log recording was either started or stopped on an
 inferior.  The @var{id} is the @value{GDBN} identifier of the thread
 group corresponding to the affected inferior.
 
+The @var{method} field indicates the method used to record execution.  If the
+method in use supports multiple recording formats, @var{format} will be present
+and contain the currently used format.  @xref{Process Record and Replay}
+for existing method and format values.
+
 @item =cmd-param-changed,param=@var{param},value=@var{value}
 Reports that a parameter of the command @code{set @var{param}} is
 changed to @var{value}.  In the multi-word @code{set} command,
diff --git a/gdb/doc/observer.texi b/gdb/doc/observer.texi
index f4049ad..fc7aac4 100644
--- a/gdb/doc/observer.texi
+++ b/gdb/doc/observer.texi
@@ -141,11 +141,16 @@ at the entry-point instruction.  For @samp{attach} and @samp{core},
 inferior, and before any information on the inferior has been printed.
 @end deftypefun
 
-@deftypefun void record_changed (struct inferior *@var{inferior}, int @var{started})
+@deftypefun void record_changed (struct inferior *@var{inferior}, int @var{started}, const char *@var{method}, const char *@var{format})
 The status of process record for inferior @var{inferior} in
 @value{GDBN} has changed.  The process record is started if
 @var{started} is true, and the process record is stopped if
 @var{started} is false.
+
+When @var{started} is true, @var{method} indicates the short name of the method
+used for recording.  If the method supports multiple formats, @var{format}
+indicates which one is being used, otherwise it is NULL.  When @var{started} is
+false, they are both NULL.
 @end deftypefun
 
 @deftypefun void solib_loaded (struct so_list *@var{solib})
diff --git a/gdb/mi/mi-interp.c b/gdb/mi/mi-interp.c
index 0fe19af..8ce816c 100644
--- a/gdb/mi/mi-interp.c
+++ b/gdb/mi/mi-interp.c
@@ -65,7 +65,8 @@ static void mi_on_no_history (void);
 
 static void mi_new_thread (struct thread_info *t);
 static void mi_thread_exit (struct thread_info *t, int silent);
-static void mi_record_changed (struct inferior*, int);
+static void mi_record_changed (struct inferior*, int, const char *,
+			       const char *);
 static void mi_inferior_added (struct inferior *inf);
 static void mi_inferior_appeared (struct inferior *inf);
 static void mi_inferior_exit (struct inferior *inf);
@@ -399,7 +400,8 @@ mi_thread_exit (struct thread_info *t, int silent)
 /* Emit notification on changing the state of record.  */
 
 static void
-mi_record_changed (struct inferior *inferior, int started)
+mi_record_changed (struct inferior *inferior, int started, const char *method,
+		   const char *format)
 {
   struct mi_interp *mi = (struct mi_interp *) top_level_interpreter_data ();
   struct cleanup *old_chain;
@@ -407,8 +409,23 @@ mi_record_changed (struct inferior *inferior, int started)
   old_chain = make_cleanup_restore_target_terminal ();
   target_terminal_ours_for_output ();
 
-  fprintf_unfiltered (mi->event_channel,  "record-%s,thread-group=\"i%d\"",
-		      started ? "started" : "stopped", inferior->num);
+  if (started)
+    {
+      if (format != NULL)
+	fprintf_unfiltered (
+	  mi->event_channel,
+	  "record-started,thread-group=\"i%d\",method=\"%s\",format=\"%s\"",
+	  inferior->num, method, format);
+      else
+	fprintf_unfiltered (
+	  mi->event_channel,
+	  "record-started,thread-group=\"i%d\",method=\"%s\"",
+	  inferior->num, method);
+    }
+  else
+    fprintf_unfiltered (mi->event_channel,
+			"record-stopped,thread-group=\"i%d\"", inferior->num);
+
 
   gdb_flush (mi->event_channel);
 
diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 77b5180..24594a9 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -206,6 +206,7 @@ record_btrace_open (const char *args, int from_tty)
 {
   struct cleanup *disable_chain;
   struct thread_info *tp;
+  const char *format;
 
   DEBUG ("open");
 
@@ -234,7 +235,8 @@ record_btrace_open (const char *args, int from_tty)
 				  NULL);
   record_btrace_generating_corefile = 0;
 
-  observer_notify_record_changed (current_inferior (),  1);
+  format = btrace_format_short_string (record_btrace_conf.format);
+  observer_notify_record_changed (current_inferior (), 1, "btrace", format);
 
   discard_cleanups (disable_chain);
 }
diff --git a/gdb/record-full.c b/gdb/record-full.c
index f307b48..0f61bcb 100644
--- a/gdb/record-full.c
+++ b/gdb/record-full.c
@@ -869,7 +869,7 @@ record_full_open (const char *name, int from_tty)
 
   record_full_init_record_breakpoints ();
 
-  observer_notify_record_changed (current_inferior (),  1);
+  observer_notify_record_changed (current_inferior (),  1, "full", NULL);
 }
 
 /* "to_close" target method.  Close the process record target.  */
diff --git a/gdb/record.c b/gdb/record.c
index 6190794..1af134f 100644
--- a/gdb/record.c
+++ b/gdb/record.c
@@ -268,7 +268,7 @@ cmd_record_stop (char *args, int from_tty)
   printf_unfiltered (_("Process record is stopped and all execution "
 		       "logs are deleted.\n"));
 
-  observer_notify_record_changed (current_inferior (), 0);
+  observer_notify_record_changed (current_inferior (), 0, NULL, NULL);
 }
 
 /* The "set record" command.  */
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 3b305a6..98a798b 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-06-06  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* gdb.mi/mi-record-changed.exp: Adjust =record-started output
+	matching.
+
 2016-06-02  Tom Tromey  <tom@tromey.com>
 
 	PR python/18984:
diff --git a/gdb/testsuite/gdb.mi/mi-record-changed.exp b/gdb/testsuite/gdb.mi/mi-record-changed.exp
index 2b5fcd6..22cf076 100644
--- a/gdb/testsuite/gdb.mi/mi-record-changed.exp
+++ b/gdb/testsuite/gdb.mi/mi-record-changed.exp
@@ -31,14 +31,14 @@ if [mi_gdb_start] {
 }
 mi_run_to_main
 
-mi_gdb_test "record" ".*=record-started,thread-group=\"i${decimal}\".*\\^done" \
+mi_gdb_test "record" ".*=record-started,thread-group=\"i${decimal}\",method=\"full\".*\\^done" \
     "record"
 mi_gdb_test "record stop" \
     ".*=record-stopped,thread-group=\"i${decimal}\".*\\^done" \
     "record end"
 
 mi_gdb_test "target record" \
-    ".*=record-started,thread-group=\"i${decimal}\".*\\^done" \
+    ".*=record-started,thread-group=\"i${decimal}\",method=\"full\".*\\^done" \
     "target record"
 
 return 0