[array] speed up array.forEach and friends by directly using in-operator

src/js/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.
 
 (function(global, utils, extrasUtils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 310 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 (HAS_INDEX(array, index, is_array)) {
+    if (HAS_INDEX(array, index)) {
       var current = array[index];
       %CreateDataProperty(deleted_elements, i, current);
     }
   }
 }
 
 
 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 (HAS_INDEX(array, from_index, is_array)) {
+        if (HAS_INDEX(array, from_index)) {
           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 (HAS_INDEX(array, from_index, is_array)) {
+        if (HAS_INDEX(array, from_index)) {
           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 676 matching lines @@
   var length = TO_LENGTH(array.length);
   return InnerArraySort(array, length, comparefn);
 }
 
 
 // The following functions cannot be made efficient on sparse arrays while
 // preserving the semantics, since the calls to the receiver function can add
 // or delete elements from the array.
 function InnerArrayFilter(f, receiver, array, length, result) {
   var result_length = 0;
-  var is_array = IS_ARRAY(array);
   for (var i = 0; i < length; i++) {
-    if (HAS_INDEX(array, i, is_array)) {
+    if (HAS_INDEX(array, i)) {
       var element = array[i];
       if (%_Call(f, receiver, element, i, array)) {
         %CreateDataProperty(result, result_length, element);
         result_length++;
       }
     }
   }
   return result;
 }
 
 
 
 function ArrayFilter(f, receiver) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.filter");
 
   // 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 = TO_OBJECT(this);
   var length = TO_LENGTH(array.length);
   if (!IS_CALLABLE(f)) throw MakeTypeError(kCalledNonCallable, f);
   var result = ArraySpeciesCreate(array, 0);
   return InnerArrayFilter(f, receiver, array, length, result);
 }
 
 
 function InnerArrayForEach(f, receiver, array, length) {
   if (!IS_CALLABLE(f)) throw MakeTypeError(kCalledNonCallable, f);
 
-  var is_array = IS_ARRAY(array);
   if (IS_UNDEFINED(receiver)) {
     for (var i = 0; i < length; i++) {
-      if (HAS_INDEX(array, i, is_array)) {
+      if (HAS_INDEX(array, i)) {
         var element = array[i];
         f(element, i, array);
       }
     }
   } else {
     for (var i = 0; i < length; i++) {
-      if (HAS_INDEX(array, i, is_array)) {
+      if (HAS_INDEX(array, i)) {
         var element = array[i];
         %_Call(f, receiver, element, i, array);
       }
     }
   }
 }
 
 
 function ArrayForEach(f, receiver) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.forEach");
 
   // 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 = TO_OBJECT(this);
   var length = TO_LENGTH(array.length);
   InnerArrayForEach(f, receiver, array, length);
 }
 
 
 function InnerArraySome(f, receiver, array, length) {
   if (!IS_CALLABLE(f)) throw MakeTypeError(kCalledNonCallable, f);
 
-  var is_array = IS_ARRAY(array);
   for (var i = 0; i < length; i++) {
-    if (HAS_INDEX(array, i, is_array)) {
+    if (HAS_INDEX(array, i)) {
       var element = array[i];
       if (%_Call(f, receiver, element, i, array)) return true;
     }
   }
   return false;
 }
 
 
 // Executes the function once for each element present in the
 // array until it finds one where callback returns true.
 function ArraySome(f, receiver) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.some");
 
   // 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 = TO_OBJECT(this);
   var length = TO_LENGTH(array.length);
   return InnerArraySome(f, receiver, array, length);
 }
 
 
 function InnerArrayEvery(f, receiver, array, length) {
   if (!IS_CALLABLE(f)) throw MakeTypeError(kCalledNonCallable, f);
 
-  var is_array = IS_ARRAY(array);
   for (var i = 0; i < length; i++) {
-    if (HAS_INDEX(array, i, is_array)) {
+    if (HAS_INDEX(array, i)) {
       var element = array[i];
       if (!%_Call(f, receiver, element, i, array)) return false;
     }
   }
   return true;
 }
 
 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 = TO_OBJECT(this);
   var length = TO_LENGTH(array.length);
   return InnerArrayEvery(f, receiver, array, length);
 }
 
 
 function ArrayMap(f, receiver) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.map");
 
   // 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 = TO_OBJECT(this);
   var length = TO_LENGTH(array.length);
   if (!IS_CALLABLE(f)) throw MakeTypeError(kCalledNonCallable, f);
   var result = ArraySpeciesCreate(array, length);
-  var is_array = IS_ARRAY(array);
   for (var i = 0; i < length; i++) {
-    if (HAS_INDEX(array, i, is_array)) {
+    if (HAS_INDEX(array, i)) {
       var element = array[i];
       %CreateDataProperty(result, i, %_Call(f, receiver, element, i, array));
     }
   }
   return result;
 }
 
 
 // For .indexOf, we don't need to pass in the number of arguments
 // at the callsite since ToInteger(undefined) == 0; however, for
@@ skipping 118 matching lines @@
   return InnerArrayLastIndexOf(this, element, index, length,
                                arguments.length);
 }
 
 
 function InnerArrayReduce(callback, current, array, length, argumentsLength) {
   if (!IS_CALLABLE(callback)) {
     throw MakeTypeError(kCalledNonCallable, callback);
   }
 
-  var is_array = IS_ARRAY(array);
   var i = 0;
   find_initial: if (argumentsLength < 2) {
     for (; i < length; i++) {
-      if (HAS_INDEX(array, i, is_array)) {
+      if (HAS_INDEX(array, i)) {
         current = array[i++];
         break find_initial;
       }
     }
     throw MakeTypeError(kReduceNoInitial);
   }
 
   for (; i < length; i++) {
-    if (HAS_INDEX(array, i, is_array)) {
+    if (HAS_INDEX(array, i)) {
       var element = array[i];
       current = callback(current, element, i, array);
     }
   }
   return current;
 }
 
 
 function ArrayReduce(callback, current) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.reduce");
 
   // 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 = TO_OBJECT(this);
   var length = TO_LENGTH(array.length);
   return InnerArrayReduce(callback, current, array, length,
                           arguments.length);
 }
 
 
 function InnerArrayReduceRight(callback, current, array, length,
                                argumentsLength) {
   if (!IS_CALLABLE(callback)) {
     throw MakeTypeError(kCalledNonCallable, callback);
   }
 
-  var is_array = IS_ARRAY(array);
   var i = length - 1;
   find_initial: if (argumentsLength < 2) {
     for (; i >= 0; i--) {
-      if (HAS_INDEX(array, i, is_array)) {
+      if (HAS_INDEX(array, i)) {
         current = array[i--];
         break find_initial;
       }
     }
     throw MakeTypeError(kReduceNoInitial);
   }
 
   for (; i >= 0; i--) {
-    if (HAS_INDEX(array, i, is_array)) {
+    if (HAS_INDEX(array, i)) {
       var element = array[i];
       current = callback(current, element, i, array);
     }
   }
   return current;
 }
 
 
 function ArrayReduceRight(callback, current) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.reduceRight");
@@ skipping 405 matching lines @@
 %InstallToContext([
   "array_pop", ArrayPop,
   "array_push", ArrayPush,
   "array_shift", ArrayShift,
   "array_splice", ArraySplice,
   "array_slice", ArraySlice,
   "array_unshift", ArrayUnshift,
 ]);
 
 });