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

src/runtime/runtime-object.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/debug.h"
 #include "src/messages.h"
@@ skipping 430 matching lines @@
   // %ObjectSeal is a fast path and these cases are handled elsewhere.
   RUNTIME_ASSERT(!object->HasSloppyArgumentsElements() &&
                  !object->map()->is_observed() && !object->IsJSProxy());
 
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, JSObject::Seal(object));
   return *result;
 }
 
 
+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);
+  if (LookupIterator::DATA == it.state()) {
+    // 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.
+    // Store empty_property_cell here to release the outdated property cell.
+    script_context->set(index, isolate->heap()->empty_property_cell());
+  }
+
+  Handle<Object> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, Object::GetProperty(&it));
+
+  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);
+  if (LookupIterator::DATA == it.state()) {
+    // 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.
+    // Store empty_property_cell here to release the outdated property cell.
+    script_context->set(index, isolate->heap()->empty_property_cell());
+  }
+
+  Handle<Object> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, result,
+      Object::SetProperty(&it, value, language_mode,
+                          Object::CERTAINLY_NOT_STORE_FROM_KEYED));
+
+  return *result;
+}
+
+
 RUNTIME_FUNCTION(Runtime_GetProperty) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 2);
 
   CONVERT_ARG_HANDLE_CHECKED(Object, object, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, key, 1);
 
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       isolate, result,
@@ skipping 969 matching lines @@
   CONVERT_PROPERTY_ATTRIBUTES_CHECKED(attrs, 3);
 
   RETURN_FAILURE_ON_EXCEPTION(
       isolate,
       JSObject::DefineAccessor(object, name, isolate->factory()->null_value(),
                                setter, attrs));
   return isolate->heap()->undefined_value();
 }
 }  // namespace internal
 }  // namespace v8