Fastpath some spread-call desugaring.

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index e484c80203fe6e9b4817c3215cc18ee95a7887e3..fa5892146025790d728cd0747edcbddbd6ef8f49 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -2430,6 +2430,16 @@ void Genesis::InitializeGlobal(Handle<JSGlobalObject> global_object,
                           Builtins::kReflectSetPrototypeOf, 2, true);
   }
 
+  {  // --- S P R E A D
+    Handle<JSObject> spread =
+        factory->NewJSObject(isolate->object_function(), TENURED);
+
+    Handle<JSFunction> apply_prepare = SimpleInstallFunction(
+        spread, factory->NewStringFromAsciiChecked("SpreadIterablePrepare"),
+        Builtins::kSpreadIterablePrepare, 1, false);

[Yang, 2016/11/08 14:08:41]

Why do we need this? I think what you want is to call a runtime function. See
src/runtime/runtime.h

[petermarshall, 2016/11/10 12:19:20]

Yep I've moved it to a runtime function

+    native_context()->set_spread_iterable_prepare(*apply_prepare);
+  }
+
   {  // --- B o u n d F u n c t i o n
     Handle<Map> map =
         factory->NewMap(JS_BOUND_FUNCTION_TYPE, JSBoundFunction::kSize);
@@ -3479,6 +3489,20 @@ bool Genesis::InstallNatives(GlobalContextType context_type) {
     if (!Bootstrapper::CompileBuiltin(isolate(), builtin_index++)) return false;
   }
 
+  // Store the initial array iterator on the native context.
+  {
+    Handle<JSFunction> array_constructor(native_context()->array_function());
+    Handle<JSObject> array_prototype(
+        JSObject::cast(array_constructor->instance_prototype()));
+
+    Handle<Object> iterator_func =
+        Object::GetProperty(array_prototype, factory()->iterator_symbol())
+            .ToHandleChecked();
+    DCHECK(iterator_func->IsJSFunction());
+    native_context()->set_initial_array_iterator(

[Yang, 2016/11/08 14:08:41]

Isn't this the same thing as native_context()->array_values_iterator()?

[petermarshall, 2016/11/10 12:19:20]

Removed this anyway - no longer needed

+        JSObject::cast(*iterator_func));
+  }
+
   if (!CallUtilsFunction(isolate(), "PostNatives")) return false;
   auto fast_template_instantiations_cache = isolate()->factory()->NewFixedArray(
       TemplateInfo::kFastTemplateInstantiationsCacheSize);