Do not waste space for the fast-case elements backing storage for ...

src/runtime.cc

 // Copyright 2006-2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 229 matching lines @@
 }
 
 
 static Handle<Object> CreateLiteralBoilerplate(
     Handle<FixedArray> literals,
     Handle<FixedArray> constant_properties);
 
 
 static Handle<Object> CreateObjectLiteralBoilerplate(
     Handle<FixedArray> literals,
-    Handle<FixedArray> constant_properties) {
+    Handle<FixedArray> constant_properties,
+    bool should_have_fast_elements) {
   // Get the global context from the literals array.  This is the
   // context in which the function was created and we use the object
   // function from this context to create the object literal.  We do
   // not use the object function from the current global context
   // because this might be the object function from another context
   // which we should not have access to.
   Handle<Context> context =
       Handle<Context>(JSFunction::GlobalContextFromLiterals(*literals));
 
   bool is_result_from_cache;
   Handle<Map> map = ComputeObjectLiteralMap(context,
                                             constant_properties,
                                             &is_result_from_cache);
 
   Handle<JSObject> boilerplate = Factory::NewJSObjectFromMap(map);
+
+  // Normalize the elements of the boilerplate to save space if needed.
+  if (!should_have_fast_elements) NormalizeElements(boilerplate);
+
   {  // Add the constant properties to the boilerplate.
     int length = constant_properties->length();
     OptimizedObjectForAddingMultipleProperties opt(boilerplate,
                                                    length / 2,
                                                    !is_result_from_cache);
     for (int index = 0; index < length; index +=2) {
       Handle<Object> key(constant_properties->get(index+0));
       Handle<Object> value(constant_properties->get(index+1));
       if (value->IsFixedArray()) {
         // The value contains the constant_properties of a
@@ skipping 61 matching lines @@
   Handle<JSArray>::cast(object)->SetContent(*content);
   return object;
 }
 
 
 static Handle<Object> CreateLiteralBoilerplate(
     Handle<FixedArray> literals,
     Handle<FixedArray> array) {
   Handle<FixedArray> elements = CompileTimeValue::GetElements(array);
   switch (CompileTimeValue::GetType(array)) {
-    case CompileTimeValue::OBJECT_LITERAL:
-      return CreateObjectLiteralBoilerplate(literals, elements);
+    case CompileTimeValue::OBJECT_LITERAL_FAST_ELEMENTS:
+      return CreateObjectLiteralBoilerplate(literals, elements, true);
+    case CompileTimeValue::OBJECT_LITERAL_SLOW_ELEMENTS:
+      return CreateObjectLiteralBoilerplate(literals, elements, false);
     case CompileTimeValue::ARRAY_LITERAL:
       return CreateArrayLiteralBoilerplate(literals, elements);
     default:
       UNREACHABLE();
       return Handle<Object>::null();
   }
 }
 
 
-static Object* Runtime_CreateObjectLiteralBoilerplate(Arguments args) {
-  HandleScope scope;
-  ASSERT(args.length() == 3);
-  // Copy the arguments.
-  CONVERT_ARG_CHECKED(FixedArray, literals, 0);
-  CONVERT_SMI_CHECKED(literals_index, args[1]);
-  CONVERT_ARG_CHECKED(FixedArray, constant_properties, 2);
-
-  Handle<Object> result =
-    CreateObjectLiteralBoilerplate(literals, constant_properties);
-
-  if (result.is_null()) return Failure::Exception();
-
-  // Update the functions literal and return the boilerplate.
-  literals->set(literals_index, *result);
-
-  return *result;
-}
-
-
 static Object* Runtime_CreateArrayLiteralBoilerplate(Arguments args) {
   // Takes a FixedArray of elements containing the literal elements of
   // the array literal and produces JSArray with those elements.
   // Additionally takes the literals array of the surrounding function
   // which contains the context from which to get the Array function
   // to use for creating the array literal.
   HandleScope scope;
   ASSERT(args.length() == 3);
   CONVERT_ARG_CHECKED(FixedArray, literals, 0);
   CONVERT_SMI_CHECKED(literals_index, args[1]);
   CONVERT_ARG_CHECKED(FixedArray, elements, 2);
 
   Handle<Object> object = CreateArrayLiteralBoilerplate(literals, elements);
   if (object.is_null()) return Failure::Exception();
 
   // Update the functions literal and return the boilerplate.
   literals->set(literals_index, *object);
   return *object;
 }
 
 
 static Object* Runtime_CreateObjectLiteral(Arguments args) {
   HandleScope scope;
-  ASSERT(args.length() == 3);
+  ASSERT(args.length() == 4);
   CONVERT_ARG_CHECKED(FixedArray, literals, 0);
   CONVERT_SMI_CHECKED(literals_index, args[1]);
   CONVERT_ARG_CHECKED(FixedArray, constant_properties, 2);
+  CONVERT_SMI_CHECKED(fast_elements, args[3]);

[Søren Thygesen Gjesse, 2010/03/11 08:28:59]

Why is this argument not a Boolean object? To save relocinfo space?

+  bool should_have_fast_elements = fast_elements == 1;
 
   // Check if boilerplate exists. If not, create it first.
   Handle<Object> boilerplate(literals->get(literals_index));
   if (*boilerplate == Heap::undefined_value()) {
-    boilerplate = CreateObjectLiteralBoilerplate(literals, constant_properties);
+    boilerplate = CreateObjectLiteralBoilerplate(literals,
+                                                 constant_properties,
+                                                 should_have_fast_elements);
     if (boilerplate.is_null()) return Failure::Exception();
     // Update the functions literal and return the boilerplate.
     literals->set(literals_index, *boilerplate);
   }
   return DeepCopyBoilerplate(JSObject::cast(*boilerplate));
 }
 
 
 static Object* Runtime_CreateObjectLiteralShallow(Arguments args) {
   HandleScope scope;
-  ASSERT(args.length() == 3);
+  ASSERT(args.length() == 4);
   CONVERT_ARG_CHECKED(FixedArray, literals, 0);
   CONVERT_SMI_CHECKED(literals_index, args[1]);
   CONVERT_ARG_CHECKED(FixedArray, constant_properties, 2);
+  CONVERT_SMI_CHECKED(fast_elements, args[3]);
+  bool should_have_fast_elements = fast_elements == 1;
 
   // Check if boilerplate exists. If not, create it first.
   Handle<Object> boilerplate(literals->get(literals_index));
   if (*boilerplate == Heap::undefined_value()) {
-    boilerplate = CreateObjectLiteralBoilerplate(literals, constant_properties);
+    boilerplate = CreateObjectLiteralBoilerplate(literals,
+                                                 constant_properties,
+                                                 should_have_fast_elements);
     if (boilerplate.is_null()) return Failure::Exception();
     // Update the functions literal and return the boilerplate.
     literals->set(literals_index, *boilerplate);
   }
   return Heap::CopyJSObject(JSObject::cast(*boilerplate));
 }
 
 
 static Object* Runtime_CreateArrayLiteral(Arguments args) {
   HandleScope scope;
@@ skipping 8310 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     Counters::gc_last_resort_from_js.Increment();
     Heap::CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal