Optimize testing for an index's existence in packed Arrays

src/array.js

 // Copyright 2012 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.
 
 "use strict";
 
 // This file relies on the fact that the following declarations have been made
 // in runtime.js:
 // var $Array = global.Array;
 
@@ skipping 280 matching lines @@
       array[key] = new_array[key];
     }
   }
 }
 
 
 // This is part of the old simple-minded splice.  We are using it either
 // because the receiver is not an array (so we have no choice) or because we
 // know we are not deleting or moving a lot of elements.
 function SimpleSlice(array, start_i, del_count, len, deleted_elements) {
+  var is_array = IS_ARRAY(array);
   for (var i = 0; i < del_count; i++) {
     var index = start_i + i;
-    if (index in array) {
+    if (HAS_INDEX(array, index, is_array)) {
       var current = array[index];
       // The spec requires [[DefineOwnProperty]] here, %AddElement is close
       // enough (in that it ignores the prototype).
       %AddElement(deleted_elements, i, current, NONE);
     }
   }
 }
 
 
 function SimpleMove(array, start_i, del_count, len, num_additional_args) {
+  var is_array = IS_ARRAY(array);
   if (num_additional_args !== del_count) {
     // Move the existing elements after the elements to be deleted
     // to the right position in the resulting array.
     if (num_additional_args > del_count) {
       for (var i = len - del_count; i > start_i; i--) {
         var from_index = i + del_count - 1;
         var to_index = i + num_additional_args - 1;
-        if (from_index in array) {
+        if (HAS_INDEX(array, from_index, is_array)) {
           array[to_index] = array[from_index];
         } else {
           delete array[to_index];
         }
       }
     } else {
       for (var i = start_i; i < len - del_count; i++) {
         var from_index = i + del_count;
         var to_index = i + num_additional_args;
-        if (from_index in array) {
+        if (HAS_INDEX(array, from_index, is_array)) {
           array[to_index] = array[from_index];
         } else {
           delete array[to_index];
         }
       }
       for (var i = len; i > len - del_count + num_additional_args; i--) {
         delete array[i - 1];
       }
     }
   }
@@ skipping 804 matching lines @@
   var needs_wrapper = false;
   if (IS_NULL_OR_UNDEFINED(receiver)) {
     receiver = %GetDefaultReceiver(f) || receiver;
   } else {
     needs_wrapper = SHOULD_CREATE_WRAPPER(f, receiver);
   }
 
   var result = new $Array();
   var accumulator = new InternalArray();
   var accumulator_length = 0;
+  var is_array = IS_ARRAY(array);
   var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
   for (var i = 0; i < length; i++) {
-    if (i in array) {
+    if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
       // Prepare break slots for debugger step in.
       if (stepping) %DebugPrepareStepInIfStepping(f);
       var new_receiver = needs_wrapper ? ToObject(receiver) : receiver;
       if (%_CallFunction(new_receiver, element, i, array, f)) {
         accumulator[accumulator_length++] = element;
       }
     }
   }
   %MoveArrayContents(accumulator, result);
@@ skipping 12 matching lines @@
   if (!IS_SPEC_FUNCTION(f)) {
     throw MakeTypeError('called_non_callable', [ f ]);
   }
   var needs_wrapper = false;
   if (IS_NULL_OR_UNDEFINED(receiver)) {
     receiver = %GetDefaultReceiver(f) || receiver;
   } else {
     needs_wrapper = SHOULD_CREATE_WRAPPER(f, receiver);
   }
 
+  var is_array = IS_ARRAY(array);
   var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
   for (var i = 0; i < length; i++) {
-    if (i in array) {
+    if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
       // Prepare break slots for debugger step in.
       if (stepping) %DebugPrepareStepInIfStepping(f);
       var new_receiver = needs_wrapper ? ToObject(receiver) : receiver;
       %_CallFunction(new_receiver, element, i, array, f);
     }
   }
 }
 
 
@@ skipping 10 matching lines @@
   if (!IS_SPEC_FUNCTION(f)) {
     throw MakeTypeError('called_non_callable', [ f ]);
   }
   var needs_wrapper = false;
   if (IS_NULL_OR_UNDEFINED(receiver)) {
     receiver = %GetDefaultReceiver(f) || receiver;
   } else {
     needs_wrapper = SHOULD_CREATE_WRAPPER(f, receiver);
   }
 
+  var is_array = IS_ARRAY(array);
   var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
   for (var i = 0; i < length; i++) {
-    if (i in array) {
+    if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
       // Prepare break slots for debugger step in.
       if (stepping) %DebugPrepareStepInIfStepping(f);
       var new_receiver = needs_wrapper ? ToObject(receiver) : receiver;
       if (%_CallFunction(new_receiver, element, i, array, f)) return true;
     }
   }
   return false;
 }
 
 
 function ArrayEvery(f, receiver) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.every");
 
   // Pull out the length so that modifications to the length in the
   // loop will not affect the looping and side effects are visible.
   var array = ToObject(this);
   var length = TO_UINT32(array.length);
 
   if (!IS_SPEC_FUNCTION(f)) {
     throw MakeTypeError('called_non_callable', [ f ]);
   }
   var needs_wrapper = false;
   if (IS_NULL_OR_UNDEFINED(receiver)) {
     receiver = %GetDefaultReceiver(f) || receiver;
   } else {
     needs_wrapper = SHOULD_CREATE_WRAPPER(f, receiver);
   }
 
+  var is_array = IS_ARRAY(array);
   var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
   for (var i = 0; i < length; i++) {
-    if (i in array) {
+    if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
       // Prepare break slots for debugger step in.
       if (stepping) %DebugPrepareStepInIfStepping(f);
       var new_receiver = needs_wrapper ? ToObject(receiver) : receiver;
       if (!%_CallFunction(new_receiver, element, i, array, f)) return false;
     }
   }
   return true;
 }
 
@@ skipping 10 matching lines @@
   }
   var needs_wrapper = false;
   if (IS_NULL_OR_UNDEFINED(receiver)) {
     receiver = %GetDefaultReceiver(f) || receiver;
   } else {
     needs_wrapper = SHOULD_CREATE_WRAPPER(f, receiver);
   }
 
   var result = new $Array();
   var accumulator = new InternalArray(length);
+  var is_array = IS_ARRAY(array);
   var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
   for (var i = 0; i < length; i++) {
-    if (i in array) {
+    if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
       // Prepare break slots for debugger step in.
       if (stepping) %DebugPrepareStepInIfStepping(f);
       var new_receiver = needs_wrapper ? ToObject(receiver) : receiver;
       accumulator[i] = %_CallFunction(new_receiver, element, i, array, f);
     }
   }
   %MoveArrayContents(accumulator, result);
   return result;
 }
@@ skipping 114 matching lines @@
 
   // Pull out the length so that modifications to the length in the
   // loop will not affect the looping and side effects are visible.
   var array = ToObject(this);
   var length = ToUint32(array.length);
 
   if (!IS_SPEC_FUNCTION(callback)) {
     throw MakeTypeError('called_non_callable', [callback]);
   }
 
+  var is_array = IS_ARRAY(array);
   var i = 0;
   find_initial: if (%_ArgumentsLength() < 2) {
     for (; i < length; i++) {
-      if (i in array) {
+      if (HAS_INDEX(array, i, is_array)) {
         current = array[i++];
         break find_initial;
       }
     }
     throw MakeTypeError('reduce_no_initial', []);
   }
 
   var receiver = %GetDefaultReceiver(callback);
   var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(callback);
   for (; i < length; i++) {
-    if (i in array) {
+    if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
       // Prepare break slots for debugger step in.
       if (stepping) %DebugPrepareStepInIfStepping(callback);
       current = %_CallFunction(receiver, current, element, i, array, callback);
     }
   }
   return current;
 }
 
 function ArrayReduceRight(callback, current) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.reduceRight");
 
   // Pull out the length so that side effects are visible before the
   // callback function is checked.
   var array = ToObject(this);
   var length = ToUint32(array.length);
 
   if (!IS_SPEC_FUNCTION(callback)) {
     throw MakeTypeError('called_non_callable', [callback]);
   }
 
+  var is_array = IS_ARRAY(array);
   var i = length - 1;
   find_initial: if (%_ArgumentsLength() < 2) {
     for (; i >= 0; i--) {
-      if (i in array) {
+      if (HAS_INDEX(array, i, is_array)) {
         current = array[i--];
         break find_initial;
       }
     }
     throw MakeTypeError('reduce_no_initial', []);
   }
 
   var receiver = %GetDefaultReceiver(callback);
   var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(callback);
   for (; i >= 0; i--) {
-    if (i in array) {
+    if (HAS_INDEX(array, i, is_array)) {
       var element = array[i];
       // Prepare break slots for debugger step in.
       if (stepping) %DebugPrepareStepInIfStepping(callback);
       current = %_CallFunction(receiver, current, element, i, array, callback);
     }
   }
   return current;
 }
 
 // ES5, 15.4.3.2
@@ skipping 85 matching lines @@
   ));
 
   SetUpLockedPrototype(InternalPackedArray, $Array(), $Array(
     "join", getFunction("join", ArrayJoin),
     "pop", getFunction("pop", ArrayPop),
     "push", getFunction("push", ArrayPush)
   ));
 }
 
 SetUpArray();