Calling a generator function returns a generator object

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index 76f0a3c9a86e052add7782f4600217d317fc5a44..90e39f2a1a9f2e5ed72cac384977cd15f4c35f7a 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -4089,9 +4089,8 @@ MaybeObject* Heap::AllocateInitialMap(JSFunction* fun) {
   int instance_size;
   int in_object_properties;
   if (fun->shared()->is_generator()) {
-    // TODO(wingo): Replace with JS_GENERATOR_OBJECT_TYPE.
-    instance_type = JS_OBJECT_TYPE;
-    instance_size = JSObject::kHeaderSize;
+    instance_type = JS_GENERATOR_OBJECT_TYPE;
+    instance_size = JSGeneratorObject::kSize;
     in_object_properties = 0;
   } else {
     instance_type = JS_OBJECT_TYPE;
@@ -4340,6 +4339,29 @@ MaybeObject* Heap::AllocateJSObjectWithAllocationSite(JSFunction* constructor,
 }
 
 
+MaybeObject* Heap::AllocateJSGeneratorObject(JSFunction *function) {
+  ASSERT(function->shared()->is_generator());
+  // Allocate the initial map if absent.
+  if (!function->has_initial_map()) {
+    Object* initial_map;
+    MaybeObject* maybe_initial_map = AllocateInitialMap(function);
+    if (!maybe_initial_map->ToObject(&initial_map)) return maybe_initial_map;

[Michael Starzinger, 2013/04/11 19:17:39]

Just use "maybe_initial_map->To()" here and make the initial_map a "Map*", this
avoids casting. I know other places do it in this verbose fashion, but those are
left-overs from a script-driven transformation.

[wingo, 2013/04/12 10:50:17]

Done.

+    function->set_initial_map(Map::cast(initial_map));
+  }
+  Map *map = function->initial_map();
+  ASSERT(map->IsMap());

[Michael Starzinger, 2013/04/11 19:17:39]

This assert is obsolete, the accessor should already assert this.

[wingo, 2013/04/12 10:50:17]

Done.

+  ASSERT(map->instance_type() == JS_GENERATOR_OBJECT_TYPE);
+  JSGeneratorObject *generator;
+  MaybeObject* maybe_generator = AllocateJSObjectFromMap(map, NOT_TENURED);

[Michael Starzinger, 2013/04/11 19:17:39]

The NOT_TENURED flag should be the default argument, just skip the argument here
as long this function doesn't support pre-tenuring.

[wingo, 2013/04/12 10:50:17]

Done.

+  if (!maybe_generator->To(&generator)) return maybe_generator;
+  generator->set_function(function);
+  generator->set_context(Smi::FromInt(0));
+  generator->set_continuation(0);
+  generator->set_operand_stack(Smi::FromInt(0));
+  return generator;
+}
+
+
 MaybeObject* Heap::AllocateJSModule(Context* context, ScopeInfo* scope_info) {
   // Allocate a fresh map. Modules do not have a prototype.
   Map* map;