Loads and stores to global vars are now made via property cell shortcuts installed into parent scri…

src/runtime/runtime-object.cc

Index: src/runtime/runtime-object.cc
diff --git a/src/runtime/runtime-object.cc b/src/runtime/runtime-object.cc
index da1ec4977be36f1965f86e60cbfd5e08c8e02fdd..ae8d72e7fa829a10ee6a2a0a6a79a8d7a5b6f306 100644
--- a/src/runtime/runtime-object.cc
+++ b/src/runtime/runtime-object.cc
@@ -448,6 +448,68 @@ RUNTIME_FUNCTION(Runtime_ObjectSeal) {
 }
 
 
+RUNTIME_FUNCTION(Runtime_LoadGlobalViaContext) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 3);
+  CONVERT_ARG_HANDLE_CHECKED(Context, script_context, 0);
+  CONVERT_SMI_ARG_CHECKED(index, 1);
+  CONVERT_ARG_HANDLE_CHECKED(Name, name, 2);
+  DCHECK(script_context->IsScriptContext());
+  DCHECK(script_context->get(index)->IsPropertyCell());
+
+  Handle<GlobalObject> global(script_context->global_object());
+
+  LookupIterator it(global, name, LookupIterator::OWN);
+
+  Handle<Object> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, Object::GetProperty(&it));
+
+  if (LookupIterator::DATA == it.state()) {

[Toon Verwaest, 2015/07/10 16:46:11]

You should probably do this check before GetProperty since otherwise it'll walk
beyond an interceptor for example. If there's an interceptor, we can essentially
never cache, since it can decide on a whim to make a property appear that wasn't
there before.

[Igor Sheludko, 2015/07/13 08:34:51]

Done.

+    // Now update cell in the script context.
+    Handle<PropertyCell> cell = it.GetPropertyCell();
+    script_context->set(index, *cell);
+  } else {
+    // This is not a fast case, so keep this access in a slow mode.

[Toon Verwaest, 2015/07/10 16:46:11]

Add comment that you're doing this just to release the property cell containing
the hole, replacing it by the single global empty one.

[Igor Sheludko, 2015/07/13 08:34:51]

Done.

+    script_context->set(index, isolate->heap()->empty_property_cell());
+  }
+  return *result;
+}
+
+
+RUNTIME_FUNCTION(Runtime_StoreGlobalViaContext) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 5);
+  CONVERT_ARG_HANDLE_CHECKED(Context, script_context, 0);
+  CONVERT_SMI_ARG_CHECKED(index, 1);
+  CONVERT_ARG_HANDLE_CHECKED(Name, name, 2);
+  CONVERT_ARG_HANDLE_CHECKED(Object, value, 3);
+  CONVERT_LANGUAGE_MODE_ARG_CHECKED(language_mode_arg, 4);
+  DCHECK(script_context->IsScriptContext());
+  DCHECK(script_context->get(index)->IsPropertyCell());
+  LanguageMode language_mode = language_mode_arg;
+
+  Handle<GlobalObject> global(script_context->global_object());
+
+  LookupIterator it(global, name, LookupIterator::OWN);
+
+  Handle<Object> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, result,
+      Object::SetProperty(&it, value, language_mode,
+                          Object::CERTAINLY_NOT_STORE_FROM_KEYED));
+
+  if (LookupIterator::DATA == it.state()) {

[Toon Verwaest, 2015/07/10 16:46:11]

Same as above.

[Igor Sheludko, 2015/07/13 08:34:51]

Done.

+    // Now update cell in the script context.
+    Handle<PropertyCell> cell = it.GetPropertyCell();
+    script_context->set(index, *cell);
+  } else {
+    // This is not a fast case, so keep this access in a slow mode.
+    script_context->set(index, isolate->heap()->empty_property_cell());
+  }
+  return *result;
+}
+
+
 RUNTIME_FUNCTION(Runtime_GetProperty) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 2);