[builtins] Improve performance of array.prototype.filter and map

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 983 matching lines @@
 
 
 function ArraySort(comparefn) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.sort");
 
   var array = TO_OBJECT(this);
   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;
-  for (var i = 0; i < length; i++) {
-    if (i in array) {
-      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 %make_type_error(kCalledNonCallable, f);
-  var result = ArraySpeciesCreate(array, 0);
-  return InnerArrayFilter(f, receiver, array, length, result);
-}
-
-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 %make_type_error(kCalledNonCallable, f);
-  var result = ArraySpeciesCreate(array, length);
-  for (var i = 0; i < length; i++) {
-    if (i in array) {
-      var element = array[i];
-      %CreateDataProperty(result, i, %_Call(f, receiver, element, i, array));
-    }
-  }
-  return result;
-}
-
-

[danno, 2017/04/03 15:35:27]

Nice. I like it.

 function ArrayLastIndexOf(element, index) {
   CHECK_OBJECT_COERCIBLE(this, "Array.prototype.lastIndexOf");
 
   var array = this;
   var length = TO_LENGTH(this.length);
 
   if (length == 0) return -1;
   if (arguments.length < 2) {
     index = length - 1;
   } else {
@@ skipping 310 matching lines @@
   "toLocaleString", getFunction("toLocaleString", ArrayToLocaleString),
   "join", getFunction("join", ArrayJoin),
   "pop", getFunction("pop", ArrayPop),
   "push", getFunction("push", ArrayPush, 1),
   "reverse", getFunction("reverse", ArrayReverse),
   "shift", getFunction("shift", ArrayShift),
   "unshift", getFunction("unshift", ArrayUnshift, 1),
   "slice", getFunction("slice", ArraySlice, 2),
   "splice", getFunction("splice", ArraySplice, 2),
   "sort", getFunction("sort", ArraySort),
-  "filter", getFunction("filter", ArrayFilter, 1),
-  "map", getFunction("map", ArrayMap, 1),
   "indexOf", getFunction("indexOf", null, 1),
   "lastIndexOf", getFunction("lastIndexOf", ArrayLastIndexOf, 1),
   "copyWithin", getFunction("copyWithin", ArrayCopyWithin, 2),
   "find", getFunction("find", ArrayFind, 1),
   "findIndex", getFunction("findIndex", ArrayFindIndex, 1),
   "fill", getFunction("fill", ArrayFill, 1),
   "includes", getFunction("includes", null, 1),
   "entries", IteratorFunctions.entries,
   "keys", IteratorFunctions.keys,
   iteratorSymbol, IteratorFunctions.values
@@ skipping 36 matching lines @@
 
 // -------------------------------------------------------------------
 // Exports
 
 utils.Export(function(to) {
   to.ArrayFrom = ArrayFrom;
   to.ArrayJoin = ArrayJoin;
   to.ArrayPush = ArrayPush;
   to.ArrayToString = ArrayToString;
   to.ArrayValues = IteratorFunctions.values,
-  to.InnerArrayFilter = InnerArrayFilter;
   to.InnerArrayFind = InnerArrayFind;
   to.InnerArrayFindIndex = InnerArrayFindIndex;
   to.InnerArrayJoin = InnerArrayJoin;
   to.InnerArraySort = InnerArraySort;
   to.InnerArrayToLocaleString = InnerArrayToLocaleString;
 });
 
 %InstallToContext([
   "array_entries_iterator", IteratorFunctions.entries,
   "array_keys_iterator", IteratorFunctions.keys,
   "array_pop", ArrayPop,
   "array_push", ArrayPush,
   "array_shift", ArrayShift,
   "array_splice", ArraySplice,
   "array_slice", ArraySlice,
   "array_unshift", ArrayUnshift,
   "array_values_iterator", IteratorFunctions.values,
 ]);
 
 });