Object.observe: implement map bit and functions to access it.

R=danno@chromium.org
BUG=

Review URL: https://codereview.chromium.org/11276028

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12866 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects-inl.h

@@ -3159,6 +3159,16 @@ bool Map::owns_descriptors() {
 }
 
 
+void Map::set_is_observed(bool is_observed) {
+  set_bit_field3(IsObserved::update(bit_field3(), is_observed));
+}
+
+
+bool Map::is_observed() {
+  return IsObserved::decode(bit_field3());
+}
+
+
 void Code::set_flags(Code::Flags flags) {
   STATIC_ASSERT(Code::NUMBER_OF_KINDS <= KindField::kMax + 1);
   // Make sure that all call stubs have an arguments count.

src/objects.h

@@ -4704,6 +4704,7 @@ class Map: public HeapObject {
   class FunctionWithPrototype:      public BitField<bool, 23,  1> {};
   class DictionaryMap:              public BitField<bool, 24,  1> {};
   class OwnsDescriptors:            public BitField<bool, 25,  1> {};
+  class IsObserved:                 public BitField<bool, 26,  1> {};
 
   // Tells whether the object in the prototype property will be used
   // for instances created from this function.  If the prototype
@@ -4971,6 +4972,8 @@ class Map: public HeapObject {
 
   inline bool owns_descriptors();
   inline void set_owns_descriptors(bool is_shared);
+  inline bool is_observed();
+  inline void set_is_observed(bool is_observed);
 
   MUST_USE_RESULT MaybeObject* RawCopy(int instance_size);
   MUST_USE_RESULT MaybeObject* CopyWithPreallocatedFieldDescriptors();

src/runtime.cc

@@ -13222,6 +13222,29 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_HaveSameMap) {
   return isolate->heap()->ToBoolean(obj1->map() == obj2->map());
 }
 
+
+RUNTIME_FUNCTION(MaybeObject*, Runtime_IsObserved) {
+  ASSERT(args.length() == 1);
+  CONVERT_ARG_CHECKED(JSReceiver, obj, 0);
+  return isolate->heap()->ToBoolean(obj->map()->is_observed());
+}
+
+
+RUNTIME_FUNCTION(MaybeObject*, Runtime_SetIsObserved) {
+  ASSERT(args.length() == 2);
+  CONVERT_ARG_CHECKED(JSReceiver, obj, 0);
+  CONVERT_BOOLEAN_ARG_CHECKED(is_observed, 1);
+  if (obj->map()->is_observed() != is_observed) {
+    MaybeObject* maybe = obj->map()->Copy();
+    Map* map;
+    if (!maybe->To<Map>(&map)) return maybe;
+    map->set_is_observed(is_observed);
+    obj->set_map(map);
+  }
+  return isolate->heap()->undefined_value();
+}
+
+
 // ----------------------------------------------------------------------------
 // Implementation of Runtime
 

src/runtime.h

@@ -317,6 +317,10 @@ namespace internal {
   F(WeakMapDelete, 2, 1) \
   F(WeakMapSet, 3, 1) \
   \
+  /* Harmony observe */ \
+  F(IsObserved, 1, 1) \
+  F(SetIsObserved, 2, 1) \
+  \
   /* Statements */ \
   F(NewClosure, 3, 1) \
   F(NewObject, 1, 1) \