gobject: add private data for GObject and use it for optional flags

Add a GObjectPrivate struct and let GObject have private data.

On architectures where we have an alignment gap in GObject struct (64
bit), we use the gap for "optional_flags". Use the private data for
those optional flags, on architectures where we don't have them.

For now, private data is only added for those optional flags (and not on
architectures, where the flags fit inside GObject). In the future, we
may add additional fields there, and add the private struct always.

The main purpose will be to replace all the global locks with per-object
locks, and make "optional_flags" also available on 32bit.

gobject/gobject.c

@@ -107,7 +107,24 @@ enum {
 #define OPTIONAL_FLAG_HAS_NOTIFY_HANDLER (1 << 2) /* Same, specifically for "notify" */
 
 #if SIZEOF_INT == 4 && GLIB_SIZEOF_VOID_P == 8
-#define HAVE_OPTIONAL_FLAGS
+#define HAVE_OPTIONAL_FLAGS_IN_GOBJECT 1
+#else
+#define HAVE_OPTIONAL_FLAGS_IN_GOBJECT 0
+#endif
+
+/* For now we only create a private struct if we don't have optional flags in
+ * GObject. Currently we don't need it otherwise. In the future we might
+ * always add a private struct. */
+#define HAVE_PRIVATE (!HAVE_OPTIONAL_FLAGS_IN_GOBJECT)
+
+#if HAVE_PRIVATE
+typedef struct {
+#if !HAVE_OPTIONAL_FLAGS_IN_GOBJECT
+	guint optional_flags; /* (atomic) */
+#endif
+} GObjectPrivate;
+
+static int GObject_private_offset;
 #endif
 
 typedef struct
@@ -116,7 +133,7 @@ typedef struct
 
   /*< private >*/
   guint          ref_count;  /* (atomic) */
-#ifdef HAVE_OPTIONAL_FLAGS
+#if HAVE_OPTIONAL_FLAGS_IN_GOBJECT
   guint          optional_flags;  /* (atomic) */
 #endif
   GData         *qdata;
@@ -190,9 +207,6 @@ static GQuark	            quark_closure_array = 0;
 static GQuark	            quark_weak_notifies = 0;
 static GQuark	            quark_toggle_refs = 0;
 static GQuark               quark_notify_queue;
-#ifndef HAVE_OPTIONAL_FLAGS
-static GQuark               quark_in_construction;
-#endif
 static GParamSpecPool      *pspec_pool = NULL;
 static gulong	            gobject_signals[LAST_SIGNAL] = { 0, };
 static guint (*floating_flag_handler) (GObject*, gint) = object_floating_flag_handler;
@@ -202,6 +216,24 @@ static GRWLock              weak_locations_lock;
 
 G_LOCK_DEFINE_STATIC(notify_lock);
 
+#if HAVE_PRIVATE
+G_ALWAYS_INLINE static inline GObjectPrivate *
+g_object_get_instance_private (GObject *object)
+{
+  return G_STRUCT_MEMBER_P (object, GObject_private_offset);
+}
+#endif
+
+G_ALWAYS_INLINE static inline guint *
+object_get_optional_flags_p (GObject *object)
+{
+#if HAVE_OPTIONAL_FLAGS_IN_GOBJECT
+  return &(((GObjectReal *) object)->optional_flags);
+#else
+  return &g_object_get_instance_private (object)->optional_flags;
+#endif
+}
+
 /* --- functions --- */
 static void
 g_object_notify_queue_free (gpointer data)
@@ -455,6 +487,11 @@ _g_object_type_init (void)
 # endif /* G_HAS_CONSTRUCTORS */
     }
 #endif /* G_ENABLE_DEBUG */
+
+#if HAVE_PRIVATE
+  GObject_private_offset =
+      g_type_add_instance_private (G_TYPE_OBJECT, sizeof (GObjectPrivate));
+#endif
 }
 
 /* Initialize the global GParamSpecPool; this function needs to be
@@ -529,9 +566,6 @@ g_object_do_class_init (GObjectClass *class)
   quark_weak_locations = g_quark_from_static_string ("GObject-weak-locations");
   quark_toggle_refs = g_quark_from_static_string ("GObject-toggle-references");
   quark_notify_queue = g_quark_from_static_string ("GObject-notify-queue");
-#ifndef HAVE_OPTIONAL_FLAGS
-  quark_in_construction = g_quark_from_static_string ("GObject-in-construction");
-#endif
 
   g_object_init_pspec_pool ();
 
@@ -589,6 +623,10 @@ g_object_do_class_init (GObjectClass *class)
    * implement an interface implement all properties for that interface
    */
   g_type_add_interface_check (NULL, object_interface_check_properties);
+
+#if HAVE_PRIVATE
+  g_type_class_adjust_private_offset (class, &GObject_private_offset);
+#endif
 }
 
 /* Sinks @pspec if it’s a floating ref. */
@@ -1183,12 +1221,7 @@ g_object_interface_list_properties (gpointer      g_iface,
 static inline guint
 object_get_optional_flags (GObject *object)
 {
-#ifdef HAVE_OPTIONAL_FLAGS
+  return g_atomic_int_get (object_get_optional_flags_p (object));
-  GObjectReal *real = (GObjectReal *)object;
-  return (guint)g_atomic_int_get (&real->optional_flags);
-#else
-  return 0;
-#endif
 }
 
 /* Variant of object_get_optional_flags for when
@@ -1198,21 +1231,14 @@ object_get_optional_flags (GObject *object)
 static inline guint
 object_get_optional_flags_X (GObject *object)
 {
-#ifdef HAVE_OPTIONAL_FLAGS
+  return *object_get_optional_flags_p (object);
-  GObjectReal *real = (GObjectReal *)object;
-  return real->optional_flags;
-#else
-  return 0;
-#endif
 }
 
-#ifdef HAVE_OPTIONAL_FLAGS
 static inline void
 object_set_optional_flags (GObject *object,
                           guint flags)
 {
-  GObjectReal *real = (GObjectReal *)object;
+  g_atomic_int_or (object_get_optional_flags_p (object), flags);
-  g_atomic_int_or (&real->optional_flags, flags);
 }
 
 /* Variant for when we have exclusive access
@@ -1222,8 +1248,7 @@ static inline void
 object_set_optional_flags_X (GObject *object,
                              guint flags)
 {
-  GObjectReal *real = (GObjectReal *)object;
+  (*object_get_optional_flags_p (object)) |= flags;
-  real->optional_flags |= flags;
 }
 
 /* Variant for when we have exclusive access
@@ -1233,83 +1258,55 @@ static inline void
 object_unset_optional_flags_X (GObject *object,
                                guint flags)
 {
-  GObjectReal *real = (GObjectReal *)object;
+  (*object_get_optional_flags_p (object)) &= ~flags;
-  real->optional_flags &= ~flags;
 }
-#endif
 
 gboolean
 _g_object_has_signal_handler (GObject *object)
 {
-#ifdef HAVE_OPTIONAL_FLAGS
   return (object_get_optional_flags (object) & OPTIONAL_FLAG_HAS_SIGNAL_HANDLER) != 0;
-#else
-  return TRUE;
-#endif
 }
 
 static inline gboolean
 _g_object_has_notify_handler (GObject *object)
 {
-#ifdef HAVE_OPTIONAL_FLAGS
   return CLASS_NEEDS_NOTIFY (G_OBJECT_GET_CLASS (object)) ||
          (object_get_optional_flags (object) & OPTIONAL_FLAG_HAS_NOTIFY_HANDLER) != 0;
-#else
-  return TRUE;
-#endif
 }
 
 static inline gboolean
 _g_object_has_notify_handler_X (GObject *object)
 {
-#ifdef HAVE_OPTIONAL_FLAGS
   return CLASS_NEEDS_NOTIFY (G_OBJECT_GET_CLASS (object)) ||
          (object_get_optional_flags_X (object) & OPTIONAL_FLAG_HAS_NOTIFY_HANDLER) != 0;
-#else
-  return TRUE;
-#endif
 }
 
 void
 _g_object_set_has_signal_handler (GObject *object,
                                   guint    signal_id)
 {
-#ifdef HAVE_OPTIONAL_FLAGS
   guint flags = OPTIONAL_FLAG_HAS_SIGNAL_HANDLER;
   if (signal_id == gobject_signals[NOTIFY])
     flags |= OPTIONAL_FLAG_HAS_NOTIFY_HANDLER;
   object_set_optional_flags (object, flags);
-#endif
 }
 
 static inline gboolean
 object_in_construction (GObject *object)
 {
-#ifdef HAVE_OPTIONAL_FLAGS
   return (object_get_optional_flags (object) & OPTIONAL_FLAG_IN_CONSTRUCTION) != 0;
-#else
-  return g_datalist_id_get_data (&object->qdata, quark_in_construction) != NULL;
-#endif
 }
 
 static inline void
 set_object_in_construction (GObject *object)
 {
-#ifdef HAVE_OPTIONAL_FLAGS
   object_set_optional_flags_X (object, OPTIONAL_FLAG_IN_CONSTRUCTION);
-#else
-  g_datalist_id_set_data (&object->qdata, quark_in_construction, object);
-#endif
 }
 
 static inline void
 unset_object_in_construction (GObject *object)
 {
-#ifdef HAVE_OPTIONAL_FLAGS
   object_unset_optional_flags_X (object, OPTIONAL_FLAG_IN_CONSTRUCTION);
-#else
-  g_datalist_id_set_data (&object->qdata, quark_in_construction, NULL);
-#endif
 }
 
 static void
@@ -1498,9 +1495,7 @@ static inline void
 g_object_notify_by_spec_internal (GObject    *object,
                                   GParamSpec *pspec)
 {
-#ifdef HAVE_OPTIONAL_FLAGS
   guint object_flags;
-#endif
   gboolean needs_notify;
   gboolean in_init;
 
@@ -1509,16 +1504,11 @@ g_object_notify_by_spec_internal (GObject    *object,
 
   param_spec_follow_override (&pspec);
 
-#ifdef HAVE_OPTIONAL_FLAGS
   /* get all flags we need with a single atomic read */
   object_flags = object_get_optional_flags (object);
   needs_notify = ((object_flags & OPTIONAL_FLAG_HAS_NOTIFY_HANDLER) != 0) ||
                   CLASS_NEEDS_NOTIFY (G_OBJECT_GET_CLASS (object));
   in_init = (object_flags & OPTIONAL_FLAG_IN_CONSTRUCTION) != 0;
-#else
-  needs_notify = TRUE;
-  in_init = object_in_construction (object);
-#endif
 
   if (pspec != NULL && needs_notify)
     {