Optimize calls to object literal properties that are initialized with a funct...

src/runtime.cc

 // Copyright 2010 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 274 matching lines @@
 
 
 static Handle<Object> CreateLiteralBoilerplate(
     Handle<FixedArray> literals,
     Handle<FixedArray> constant_properties);
 
 
 static Handle<Object> CreateObjectLiteralBoilerplate(
     Handle<FixedArray> literals,
     Handle<FixedArray> constant_properties,
-    bool should_have_fast_elements) {
+    bool should_have_fast_elements,
+    bool has_function_literal) {
   // 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);
+  // In case we have function literals, we want the object to be in
+  // slow properties mode for now and we don't go in the map cache.

[Mads Ager (chromium), 2011/02/01 13:51:00]

Please expand the comment to say that we cannot share the maps in any case
because the constant functions will rarely (never?) be the same.

[fschneider, 2011/02/02 10:18:38]

Done.

+  bool is_result_from_cache = false;
+  Handle<Map> map = has_function_literal
+      ? Handle<Map>(context->object_function()->initial_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
-        // simple object literal.
-        Handle<FixedArray> array = Handle<FixedArray>::cast(value);
-        value = CreateLiteralBoilerplate(literals, array);
-        if (value.is_null()) return value;
-      }
-      Handle<Object> result;
-      uint32_t element_index = 0;
-      if (key->IsSymbol()) {
-        if (Handle<String>::cast(key)->AsArrayIndex(&element_index)) {
-          // Array index as string (uint32).
-          result = SetOwnElement(boilerplate, element_index, value);
-        } else {
-          Handle<String> name(String::cast(*key));
-          ASSERT(!name->AsArrayIndex(&element_index));
-          result = SetLocalPropertyIgnoreAttributes(boilerplate, name,
-                                                    value, NONE);
-        }
-      } else if (key->ToArrayIndex(&element_index)) {
-        // Array index (uint32).
+  // Add the constant properties to the boilerplate.
+  int length = constant_properties->length();
+  bool should_transform =
+      !is_result_from_cache && boilerplate->HasFastProperties();
+  if (should_transform || has_function_literal) {
+    // Normalize the properties of object to avoid n^2 behavior
+    // when extending the object multiple properties. Indicate the number of
+    // properties to be added.
+    NormalizeProperties(boilerplate, KEEP_INOBJECT_PROPERTIES, length / 2);
+  }
+
+  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
+      // simple object or array literal.
+      Handle<FixedArray> array = Handle<FixedArray>::cast(value);
+      value = CreateLiteralBoilerplate(literals, array);
+      if (value.is_null()) return value;
+    }
+    Handle<Object> result;
+    uint32_t element_index = 0;
+    if (key->IsSymbol()) {
+      if (Handle<String>::cast(key)->AsArrayIndex(&element_index)) {
+        // Array index as string (uint32).
         result = SetOwnElement(boilerplate, element_index, value);
       } else {
-        // Non-uint32 number.
-        ASSERT(key->IsNumber());
-        double num = key->Number();
-        char arr[100];
-        Vector<char> buffer(arr, ARRAY_SIZE(arr));
-        const char* str = DoubleToCString(num, buffer);
-        Handle<String> name = Factory::NewStringFromAscii(CStrVector(str));
+        Handle<String> name(String::cast(*key));
+        ASSERT(!name->AsArrayIndex(&element_index));
         result = SetLocalPropertyIgnoreAttributes(boilerplate, name,
                                                   value, NONE);
       }
-      // If setting the property on the boilerplate throws an
-      // exception, the exception is converted to an empty handle in
-      // the handle based operations.  In that case, we need to
-      // convert back to an exception.
-      if (result.is_null()) return result;
+    } else if (key->ToArrayIndex(&element_index)) {
+      // Array index (uint32).
+      result = SetOwnElement(boilerplate, element_index, value);
+    } else {
+      // Non-uint32 number.
+      ASSERT(key->IsNumber());
+      double num = key->Number();
+      char arr[100];
+      Vector<char> buffer(arr, ARRAY_SIZE(arr));
+      const char* str = DoubleToCString(num, buffer);
+      Handle<String> name = Factory::NewStringFromAscii(CStrVector(str));
+      result = SetLocalPropertyIgnoreAttributes(boilerplate, name,
+                                                value, NONE);
     }
+    // If setting the property on the boilerplate throws an
+    // exception, the exception is converted to an empty handle in
+    // the handle based operations.  In that case, we need to
+    // convert back to an exception.
+    if (result.is_null()) return result;
+  }
+
+  // Transform to fast properties if necessary. For object literals with
+  // containing function literals we defer this operation until after all
+  // computed properties have been assigned so that we can generate
+  // constant function properties.
+  if (should_transform && !has_function_literal) {
+    TransformToFastProperties(boilerplate,
+                              boilerplate->map()->unused_property_fields());
   }
 
   return boilerplate;
 }
 
 
 static Handle<Object> CreateArrayLiteralBoilerplate(
     Handle<FixedArray> literals,
     Handle<FixedArray> elements) {
   // Create the JSArray.
@@ skipping 10 matching lines @@
 #ifdef DEBUG
     // Copy-on-write arrays must be shallow (and simple).
     for (int i = 0; i < content->length(); i++) {
       ASSERT(!content->get(i)->IsFixedArray());
     }
 #endif
   } else {
     for (int i = 0; i < content->length(); i++) {
       if (content->get(i)->IsFixedArray()) {
         // The value contains the constant_properties of a
-        // simple object literal.
+        // simple object or array literal.
         Handle<FixedArray> fa(FixedArray::cast(content->get(i)));
         Handle<Object> result =
             CreateLiteralBoilerplate(literals, fa);
         if (result.is_null()) return result;
         content->set(i, *result);
       }
     }
   }
 
   // Set the elements.
   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_FAST_ELEMENTS:
-      return CreateObjectLiteralBoilerplate(literals, elements, true);
+      return CreateObjectLiteralBoilerplate(literals, elements, true, false);
     case CompileTimeValue::OBJECT_LITERAL_SLOW_ELEMENTS:
-      return CreateObjectLiteralBoilerplate(literals, elements, false);
+      return CreateObjectLiteralBoilerplate(literals, elements, false, false);
     case CompileTimeValue::ARRAY_LITERAL:
       return CreateArrayLiteralBoilerplate(literals, elements);
     default:
       UNREACHABLE();
       return Handle<Object>::null();
   }
 }
 
 
 static MaybeObject* Runtime_CreateArrayLiteralBoilerplate(Arguments args) {
@@ skipping 16 matching lines @@
   return *object;
 }
 
 
 static MaybeObject* Runtime_CreateObjectLiteral(Arguments args) {
   HandleScope scope;
   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;
+  CONVERT_SMI_CHECKED(flags, args[3]);
+  bool should_have_fast_elements = (flags & ObjectLiteral::kFastElements) != 0;
+  bool has_function_literal = (flags & ObjectLiteral::kHasFunction) != 0;
 
   // 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,
-                                                 should_have_fast_elements);
+                                                 should_have_fast_elements,
+                                                 has_function_literal);
     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 MaybeObject* Runtime_CreateObjectLiteralShallow(Arguments args) {
   HandleScope scope;
   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;
+  CONVERT_SMI_CHECKED(flags, args[3]);
+  bool should_have_fast_elements = (flags & ObjectLiteral::kFastElements) != 0;
+  bool has_function_literal = (flags & ObjectLiteral::kHasFunction) != 0;
 
   // 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,
-                                                 should_have_fast_elements);
+                                                 should_have_fast_elements,
+                                                 has_function_literal);
     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 MaybeObject* Runtime_CreateArrayLiteral(Arguments args) {
   HandleScope scope;
@@ skipping 10375 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