[Interpreter] Implement ForIn in bytecode graph builder.

src/runtime/runtime-interpreter.cc

Index: src/runtime/runtime-interpreter.cc
diff --git a/src/runtime/runtime-interpreter.cc b/src/runtime/runtime-interpreter.cc
index c22e6808c3e19c763b35ab61d559b236638c5116..2f3cd0222ee2e534426a2d63e748d9f1f2574a6a 100644
--- a/src/runtime/runtime-interpreter.cc
+++ b/src/runtime/runtime-interpreter.cc
@@ -148,20 +148,51 @@ RUNTIME_FUNCTION(Runtime_InterpreterNewClosure) {
 }
 
 
+namespace {
+
+MaybeHandle<JSReceiver> ToObjectHelper(Object** args_object, Isolate* isolate) {
+  Object* o = Runtime_ToObject(1, args_object, isolate);
+  return MaybeHandle<JSReceiver>(handle(JSReceiver::cast(o), isolate));
+}
+
+
+MaybeHandle<Object> GetPropertyNamesFastHelper(Object** args_object,
+                                               Isolate* isolate) {
+  Object* o = Runtime_GetPropertyNamesFast(1, args_object, isolate);
+  return MaybeHandle<Object>(handle(Object::cast(o), isolate));
+}
+
+}  // namespace
+
+
 RUNTIME_FUNCTION(Runtime_InterpreterForInPrepare) {
   HandleScope scope(isolate);
-  DCHECK_EQ(2, args.length());
-  CONVERT_ARG_HANDLE_CHECKED(JSReceiver, receiver, 0);
-  CONVERT_ARG_HANDLE_CHECKED(HeapObject, property_names, 1);
+  DCHECK_EQ(1, args.length());
 
-  Handle<Object> cache_type = property_names;
-  Handle<Map> cache_type_map = handle(property_names->map(), isolate);
-  Handle<Map> receiver_map = handle(receiver->map(), isolate);
+  // Initialize return return triple such that cache_length is zero

[rmcilroy, 2015/12/17 15:43:27]

extra "return"

[oth, 2015/12/17 19:28:24]

Done.

+  // which'll coax ForInDone to quit on first attempt.

[rmcilroy, 2015/12/17 15:43:27]

s/first attempt/first attempt if this function returns early/ 

[oth, 2015/12/17 19:28:24]

Done.

+  Handle<FixedArray> result = isolate->factory()->NewFixedArray(4);
+  result->set(3, Smi::FromInt(0));
+
+  // Cast to accumulator

[rmcilroy, 2015/12/17 15:43:27]

/a/accumulator/object

[oth, 2015/12/17 19:28:24]

Done.

+  Handle<JSReceiver> receiver;
+  ASSIGN_RETURN_ON_EXCEPTION_VALUE(
+      isolate, receiver, ToObjectHelper(args.arguments(), isolate), *result);
+
+  Handle<Object> cache_type;
+  ASSIGN_RETURN_ON_EXCEPTION_VALUE(
+      isolate, cache_type,
+      GetPropertyNamesFastHelper(Handle<Object>::cast(receiver).location(),
+                                 isolate),
+      *result);
 
+  Handle<Map> receiver_map = handle(receiver->map(), isolate);
   Handle<FixedArray> cache_array;
   int cache_length;
-
-  if (cache_type_map.is_identical_to(isolate->factory()->meta_map())) {
+  if (cache_type->IsMap()) {
+    Handle<Map> cache_type_map =
+        handle(Handle<Map>::cast(cache_type)->map(), isolate);
+    DCHECK(cache_type_map.is_identical_to(isolate->factory()->meta_map()));
     int enum_length = cache_type_map->EnumLength();
     DescriptorArray* descriptors = receiver_map->instance_descriptors();
     if (enum_length > 0 && descriptors->HasEnumCache()) {
@@ -185,14 +216,12 @@ RUNTIME_FUNCTION(Runtime_InterpreterForInPrepare) {
     }
   }
 
-  Handle<FixedArray> result = isolate->factory()->NewFixedArray(4);
   result->set(0, *receiver);
-  result->set(1, *cache_array);
-  result->set(2, *cache_type);
+  result->set(1, *cache_type);
+  result->set(2, *cache_array);
   result->set(3, Smi::FromInt(cache_length));
   return *result;
 }
 
-
 }  // namespace internal
 }  // namespace v8