Move some code from Runtime_GetPrototype into a new Object::GetPrototype.

Also clean up the access check, which was doing too much.

This is in preparation of implementing Reflect.getPrototypeOf.

BUG=

Review URL: https://codereview.chromium.org/1402973002

Cr-Commit-Position: refs/heads/master@{#31434}

src/objects-inl.h

@@ -1199,15 +1199,22 @@ MaybeHandle<Object> Object::SetElement(Isolate* isolate, Handle<Object> object,
 }
 
 
-Handle<Object> Object::GetPrototypeSkipHiddenPrototypes(
-    Isolate* isolate, Handle<Object> receiver) {
-  PrototypeIterator iter(isolate, receiver);
-  while (!iter.IsAtEnd(PrototypeIterator::END_AT_NON_HIDDEN)) {
+Handle<Object> Object::GetPrototype(Isolate* isolate, Handle<Object> obj) {
+  // We don't expect access checks to be needed on JSProxy objects.
+  DCHECK(!obj->IsAccessCheckNeeded() || obj->IsJSObject());
+  Handle<Context> context(isolate->context());
+  if (obj->IsAccessCheckNeeded() &&
+      !isolate->MayAccess(context, Handle<JSObject>::cast(obj))) {
+    return isolate->factory()->null_value();
+  }
+
+  PrototypeIterator iter(isolate, obj, PrototypeIterator::START_AT_RECEIVER);
+  do {
+    iter.AdvanceIgnoringProxies();
     if (PrototypeIterator::GetCurrent(iter)->IsJSProxy()) {
       return PrototypeIterator::GetCurrent(iter);
     }
-    iter.Advance();
-  }
+  } while (!iter.IsAtEnd(PrototypeIterator::END_AT_NON_HIDDEN));
   return PrototypeIterator::GetCurrent(iter);
 }
 

src/objects.cc

@@ -13886,7 +13886,7 @@ MaybeHandle<Object> JSObject::SetPrototype(Handle<JSObject> object,
   const bool observed = from_javascript && object->map()->is_observed();
   Handle<Object> old_value;
   if (observed) {
-    old_value = Object::GetPrototypeSkipHiddenPrototypes(isolate, object);
+    old_value = Object::GetPrototype(isolate, object);
   }
 
   Handle<Object> result;
@@ -13895,8 +13895,7 @@ MaybeHandle<Object> JSObject::SetPrototype(Handle<JSObject> object,
       Object);
 
   if (observed) {
-    Handle<Object> new_value =
-        Object::GetPrototypeSkipHiddenPrototypes(isolate, object);
+    Handle<Object> new_value = Object::GetPrototype(isolate, object);
     if (!new_value->SameValue(*old_value)) {
       RETURN_ON_EXCEPTION(isolate,
                           JSObject::EnqueueChangeRecord(

src/objects.h

@@ -1290,8 +1290,9 @@ class Object {
       Isolate* isolate, Handle<Object> object, uint32_t index,
       Handle<Object> value, LanguageMode language_mode);
 
-  static inline Handle<Object> GetPrototypeSkipHiddenPrototypes(
-      Isolate* isolate, Handle<Object> receiver);
+  // Get the first non-hidden prototype.
+  static inline Handle<Object> GetPrototype(Isolate* isolate,
+                                            Handle<Object> receiver);
 
   bool HasInPrototypeChain(Isolate* isolate, Object* object);
 

src/runtime/runtime-debug.cc

@@ -1449,7 +1449,7 @@ RUNTIME_FUNCTION(Runtime_DebugGetPrototype) {
   HandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSObject, obj, 0);
-  return *Object::GetPrototypeSkipHiddenPrototypes(isolate, obj);
+  return *Object::GetPrototype(isolate, obj);
 }
 
 

src/runtime/runtime-object.cc

@@ -157,22 +157,7 @@ RUNTIME_FUNCTION(Runtime_GetPrototype) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(Object, obj, 0);
-  // We don't expect access checks to be needed on JSProxy objects.
-  DCHECK(!obj->IsAccessCheckNeeded() || obj->IsJSObject());
-  PrototypeIterator iter(isolate, obj, PrototypeIterator::START_AT_RECEIVER);
-  Handle<Context> context(isolate->context());
-  do {
-    if (PrototypeIterator::GetCurrent(iter)->IsAccessCheckNeeded() &&
-        !isolate->MayAccess(context,
-                            PrototypeIterator::GetCurrent<JSObject>(iter))) {
-      return isolate->heap()->null_value();
-    }
-    iter.AdvanceIgnoringProxies();
-    if (PrototypeIterator::GetCurrent(iter)->IsJSProxy()) {
-      return *PrototypeIterator::GetCurrent(iter);
-    }
-  } while (!iter.IsAtEnd(PrototypeIterator::END_AT_NON_HIDDEN));
-  return *PrototypeIterator::GetCurrent(iter);
+  return *Object::GetPrototype(isolate, obj);
 }
 
 

test/cctest/test-api.cc

@@ -17989,13 +17989,6 @@ THREADED_TEST(Regress93759) {
     Object::New(isolate);
   object_with_hidden->SetPrototype(hidden_prototype);
 
-  // Hidden prototype with security check on the hidden prototype.
-  Local<Object> protected_hidden_prototype =
-      protected_hidden_proto_template->GetFunction()->NewInstance();
-  Local<Object> object_with_protected_hidden =
-    Object::New(isolate);
-  object_with_protected_hidden->SetPrototype(protected_hidden_prototype);
-
   context->Exit();
 
   // Template for object for second context. Values to test are put on it as
@@ -18006,7 +17999,6 @@ THREADED_TEST(Regress93759) {
   global_template->Set(v8_str("global"), global_object);
   global_template->Set(v8_str("proxy"), proxy_object);
   global_template->Set(v8_str("hidden"), object_with_hidden);
-  global_template->Set(v8_str("phidden"), object_with_protected_hidden);
 
   LocalContext context2(NULL, global_template);
 
@@ -18025,9 +18017,6 @@ THREADED_TEST(Regress93759) {
   Local<Value> result5 = CompileRun("Object.getPrototypeOf(hidden)");
   CHECK(result5->Equals(
       object_with_hidden->GetPrototype()->ToObject(isolate)->GetPrototype()));
-
-  Local<Value> result6 = CompileRun("Object.getPrototypeOf(phidden)");
-  CHECK(result6->IsNull());
 }