Implement immutable prototype chains

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 04fb78e6dd2e8795821cb3bedeb9cad5577ee619..27a63c3ce0b199baceb11386a7d14f03895e22d0 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -4715,6 +4715,13 @@ bool Map::is_migration_target() {
   return IsMigrationTarget::decode(bit_field3());
 }
 
+void Map::set_immutable_proto(bool value) {
+  set_bit_field3(ImmutablePrototype::update(bit_field3(), value));
+}
+
+bool Map::is_immutable_proto() {
+  return ImmutablePrototype::decode(bit_field3());
+}
 
 void Map::set_new_target_is_base(bool value) {
   set_bit_field3(NewTargetIsBase::update(bit_field3(), value));
@@ -5621,8 +5628,25 @@ ACCESSORS(FunctionTemplateInfo, shared_function_info, Object,
 SMI_ACCESSORS(FunctionTemplateInfo, flag, kFlagOffset)
 
 ACCESSORS(ObjectTemplateInfo, constructor, Object, kConstructorOffset)
-ACCESSORS(ObjectTemplateInfo, internal_field_count, Object,
-          kInternalFieldCountOffset)
+ACCESSORS(ObjectTemplateInfo, data, Object, kDataOffset)
+int ObjectTemplateInfo::internal_field_count() const {
+  Object* value = data();
+  DCHECK(value->IsSmi());
+  return Smi::cast(value)->value() >> 1;

[Toon Verwaest, 2016/06/30 15:35:33]

You probably want to use BitField to designate the bits, decode and combine
them. E.g., set_data(Smi::FromInt(InternalFieldCount::update(data->value(),
new_count)));

[Dan Ehrenberg, 2016/06/30 23:12:41]

Done

+}
+void ObjectTemplateInfo::set_internal_field_count(int count) {
+  DCHECK(count << 1 < Smi::kMaxValue);
+  return set_data(Smi::FromInt((immutable_proto() ? 1 : 0) | (count << 1)));
+}
+bool ObjectTemplateInfo::immutable_proto() const {
+  Object* value = data();
+  DCHECK(value->IsSmi());
+  return Smi::cast(value)->value() & 1;
+}
+void ObjectTemplateInfo::set_immutable_proto(bool immutable) {
+  return set_data(
+      Smi::FromInt((immutable ? 1 : 0) | (internal_field_count() << 1)));
+}
 
 ACCESSORS(AllocationSite, transition_info, Object, kTransitionInfoOffset)
 ACCESSORS(AllocationSite, nested_site, Object, kNestedSiteOffset)