Remove oob elements collected from the prototype chain by trimming in GetArrayKeys

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 254 matching lines @@
     for (var i = start_i; i < limit; ++i) {
       var current = array[i];
       if (!IS_UNDEFINED(current) || i in array) {
         DefineIndexedProperty(deleted_elements, i - start_i, current);
       }
     }
   } else {
     var length = indices.length;
     for (var k = 0; k < length; ++k) {
       var key = indices[k];
-      if (!IS_UNDEFINED(key)) {
-        if (key >= start_i) {
-          var current = array[key];
-          if (!IS_UNDEFINED(current) || key in array) {
-            DefineIndexedProperty(deleted_elements, key - start_i, current);
-          }
+      if (key >= start_i) {
+        var current = array[key];
+        if (!IS_UNDEFINED(current) || key in array) {
+          DefineIndexedProperty(deleted_elements, key - start_i, current);
         }
       }
     }
   }
 }
 
 
 // This function implements the optimized splice implementation that can use
 // special array operations to handle sparse arrays in a sensible fashion.
 function SparseMove(array, start_i, del_count, len, num_additional_args) {
@@ skipping 16 matching lines @@
     for (var i = start_i + del_count; i < limit; ++i) {
       var current = array[i];
       if (!IS_UNDEFINED(current) || i in array) {
         new_array[i - del_count + num_additional_args] = current;
       }
     }
   } else {
     var length = indices.length;
     for (var k = 0; k < length; ++k) {
       var key = indices[k];
-      if (!IS_UNDEFINED(key)) {
-        if (key < start_i) {
-          var current = array[key];
-          if (!IS_UNDEFINED(current) || key in array) {
-            new_array[key] = current;
-          }
-        } else if (key >= start_i + del_count) {
-          var current = array[key];
-          if (!IS_UNDEFINED(current) || key in array) {
-            var new_key = key - del_count + num_additional_args;
-            new_array[new_key] = current;
-            if (new_key > 0xfffffffe) {
-              big_indices = big_indices || new InternalArray();
-              big_indices.push(new_key);
-            }
+      if (key < start_i) {
+        var current = array[key];
+        if (!IS_UNDEFINED(current) || key in array) {
+          new_array[key] = current;
+        }
+      } else if (key >= start_i + del_count) {
+        var current = array[key];
+        if (!IS_UNDEFINED(current) || key in array) {
+          var new_key = key - del_count + num_additional_args;
+          new_array[new_key] = current;
+          if (new_key > 0xfffffffe) {
+            big_indices = big_indices || new InternalArray();
+            big_indices.push(new_key);
           }
         }
       }
     }
   }
   // Move contents of new_array into this array
   %MoveArrayContents(new_array, array);
   // Add any moved values that aren't elements anymore.
   if (!IS_UNDEFINED(big_indices)) {
     var length = big_indices.length;
@@ skipping 717 matching lines @@
         var proto_length = indices;
         for (var i = 0; i < proto_length; i++) {
           if (!HAS_OWN_PROPERTY(obj, i) && HAS_OWN_PROPERTY(proto, i)) {
             obj[i] = proto[i];
             if (i >= max) { max = i + 1; }
           }
         }
       } else {
         for (var i = 0; i < indices.length; i++) {
           var index = indices[i];
-          if (!IS_UNDEFINED(index) && !HAS_OWN_PROPERTY(obj, index)
-              && HAS_OWN_PROPERTY(proto, index)) {
+          if (!HAS_OWN_PROPERTY(obj, index) && HAS_OWN_PROPERTY(proto, index)) {
             obj[index] = proto[index];
             if (index >= max) { max = index + 1; }
           }
         }
       }
     }
     return max;
   };
 
   // Set a value of "undefined" on all indices in the range from..to
   // where a prototype of obj has an element. I.e., shadow all prototype
   // elements in that range.
   var ShadowPrototypeElements = function(obj, from, to) {
     for (var proto = %_GetPrototype(obj); proto; proto = %_GetPrototype(proto)) {
       var indices = %GetArrayKeys(proto, to);
       if (IS_NUMBER(indices)) {
         // It's an interval.
         var proto_length = indices;
         for (var i = from; i < proto_length; i++) {
           if (HAS_OWN_PROPERTY(proto, i)) {
             obj[i] = UNDEFINED;
           }
         }
       } else {
         for (var i = 0; i < indices.length; i++) {
           var index = indices[i];
-          if (!IS_UNDEFINED(index) && from <= index &&
-              HAS_OWN_PROPERTY(proto, index)) {
+          if (from <= index && HAS_OWN_PROPERTY(proto, index)) {
             obj[index] = UNDEFINED;
           }
         }
       }
     }
   };
 
   var SafeRemoveArrayHoles = function SafeRemoveArrayHoles(obj) {
     // Copy defined elements from the end to fill in all holes and undefineds
     // in the beginning of the array.  Write undefineds and holes at the end
@@ skipping 263 matching lines @@
       // Fall through to loop below.
     } else {
       if (indices.length == 0) return -1;
       // Get all the keys in sorted order.
       var sortedKeys = GetSortedArrayKeys(array, indices);
       var n = sortedKeys.length;
       var i = 0;
       while (i < n && sortedKeys[i] < index) i++;
       while (i < n) {
         var key = sortedKeys[i];
-        if (!IS_UNDEFINED(key) && array[key] === element) return key;
+        if (array[key] === element) return key;
         i++;
       }
       return -1;
     }
   }
   // Lookup through the array.
   if (!IS_UNDEFINED(element)) {
     for (var i = min; i < max; i++) {
       if (array[i] === element) return i;
     }
@@ skipping 38 matching lines @@
       // It's an interval.
       max = indices;  // Capped by index already.
       // Fall through to loop below.
     } else {
       if (indices.length == 0) return -1;
       // Get all the keys in sorted order.
       var sortedKeys = GetSortedArrayKeys(array, indices);
       var i = sortedKeys.length - 1;
       while (i >= 0) {
         var key = sortedKeys[i];
-        if (!IS_UNDEFINED(key) && array[key] === element) return key;
+        if (array[key] === element) return key;
         i--;
       }
       return -1;
     }
   }
   // Lookup through the array.
   if (!IS_UNDEFINED(element)) {
     for (var i = max; i >= min; i--) {
       if (array[i] === element) return i;
     }
@@ skipping 509 matching lines @@
 %InstallToContext([
   "array_pop", ArrayPop,
   "array_push", ArrayPush,
   "array_shift", ArrayShift,
   "array_splice", ArraySplice,
   "array_slice", ArraySlice,
   "array_unshift", ArrayUnshift,
 ]);
 
 });