Speed up non-interceptor case of Object.getOwnPropertyNames

src/v8natives.js

 // Copyright 2012 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 1000 matching lines @@
   if (%IsJSProxy(obj)) {
     var handler = %GetHandler(obj);
     var names = CallTrap0(handler, "getOwnPropertyNames", void 0);
     return ToStringArray(names, "getOwnPropertyNames");
   }
 
   // Find all the indexed properties.
 
   // Get the local element names.
   var propertyNames = %GetLocalElementNames(obj);
+  for (var i = 0; i < propertyNames.length; ++i) {
+    propertyNames[i] = %_NumberToString(propertyNames[i]);
+  }
 
   // Get names for indexed interceptor properties.
-  if (%GetInterceptorInfo(obj) & 1) {
+  var interceptorInfo = %GetInterceptorInfo(obj);
+  if ((interceptorInfo & 1) != 0) {
     var indexedInterceptorNames =
         %GetIndexedInterceptorElementNames(obj);
     if (indexedInterceptorNames) {
       propertyNames = propertyNames.concat(indexedInterceptorNames);
     }
   }
 
   // Find all the named properties.
 
   // Get the local property names.
   propertyNames = propertyNames.concat(%GetLocalPropertyNames(obj));
 
   // Get names for named interceptor properties if any.
-
-  if (%GetInterceptorInfo(obj) & 2) {
+  if ((interceptorInfo & 2) != 0) {
     var namedInterceptorNames =
         %GetNamedInterceptorPropertyNames(obj);
     if (namedInterceptorNames) {
       propertyNames = propertyNames.concat(namedInterceptorNames);
     }
   }
 
-  // Property names are expected to be unique strings.
-  var propertySet = { __proto__: null };
-  var j = 0;
-  for (var i = 0; i < propertyNames.length; ++i) {
-    var name = ToString(propertyNames[i]);
-    // We need to check for the exact property value since for intrinsic
-    // properties like toString if(propertySet["toString"]) will always
-    // succeed.
-    if (propertySet[name] === true) {
-      continue;
+  // Property names are expected to be unique strings,
+  // but interceptors can interfere with that assumption.
+  if (interceptorInfo != 0) {
+    var propertySet = { __proto__: null };
+    var j = 0;
+    for (var i = 0; i < propertyNames.length; ++i) {
+      var name = ToString(propertyNames[i]);
+      // We need to check for the exact property value since for intrinsic
+      // properties like toString if(propertySet["toString"]) will always
+      // succeed.
+      if (propertySet[name] === true) {
+        continue;
+      }
+      propertySet[name] = true;
+      propertyNames[j++] = name;
     }
-    propertySet[name] = true;
-    propertyNames[j++] = name;
+    propertyNames.length = j;
   }
-  propertyNames.length = j;
 
   return propertyNames;
 }
 
 
 // ES5 section 15.2.3.5.
 function ObjectCreate(proto, properties) {
   if (!IS_SPEC_OBJECT(proto) && proto !== null) {
     throw MakeTypeError("proto_object_or_null", [proto]);
   }
@@ skipping 647 matching lines @@
 
 function SetUpFunction() {
   %CheckIsBootstrapping();
   InstallFunctions($Function.prototype, DONT_ENUM, $Array(
     "bind", FunctionBind,
     "toString", FunctionToString
   ));
 }
 
 SetUpFunction();