Replace PushIfAbsent by a Stack object

This significantly speeds up String(array).
BUG=

Review URL: https://codereview.chromium.org/1775403008

Cr-Commit-Position: refs/heads/master@{#34745}

src/js/array.js

@@ -73,17 +73,13 @@ function DefineIndexedProperty(array, i, value) {
   }
 }
 
+function KeySortCompare(a, b) {
+  return a - b;
+}
 
-// Global list of arrays visited during toString, toLocaleString and
-// join invocations.
-var visited_arrays = new InternalArray();
-
-
-// Gets a sorted array of array keys.  Useful for operations on sparse
-// arrays.  Dupes have not been removed.
 function GetSortedArrayKeys(array, indices) {
-  var keys = new InternalArray();
   if (IS_NUMBER(indices)) {
+    var keys = new InternalArray();
     // It's an interval
     var limit = indices;
     for (var i = 0; i < limit; ++i) {
@@ -92,61 +88,33 @@ function GetSortedArrayKeys(array, indices) {
         keys.push(i);
       }
     }
-  } else {
-    var length = indices.length;
-    for (var k = 0; k < length; ++k) {
-      var key = indices[k];
-      if (!IS_UNDEFINED(key)) {
-        var e = array[key];
-        if (!IS_UNDEFINED(e) || key in array) {
-          keys.push(key);
-        }
-      }
-    }
-    keys.sort(function(a, b) { return a - b; });
   }
-  return keys;
+  return InnerArraySort(indices, indices.length, KeySortCompare);
 }
 
 
-function SparseJoinWithSeparatorJS(array, len, convert, separator) {
-  var keys = GetSortedArrayKeys(array, %GetArrayKeys(array, len));
-  var totalLength = 0;
-  var elements = new InternalArray(keys.length * 2);
-  var previousKey = -1;
-  for (var i = 0; i < keys.length; i++) {
+function SparseJoinWithSeparatorJS(array, keys, length, convert, separator) {
+  var keys_length = keys.length;
+  var elements = new InternalArray(keys_length * 2);
+  for (var i = 0; i < keys_length; i++) {
     var key = keys[i];
-    if (key != previousKey) {  // keys may contain duplicates.
     var e = array[key];
-      if (!IS_STRING(e)) e = convert(e);
     elements[i * 2] = key;
-      elements[i * 2 + 1] = e;
-      previousKey = key;
-    }
+    elements[i * 2 + 1] = IS_STRING(e) ? e : convert(e);
   }
-  return %SparseJoinWithSeparator(elements, len, separator);
+  return %SparseJoinWithSeparator(elements, length, separator);
 }
 
 
 // Optimized for sparse arrays if separator is ''.
-function SparseJoin(array, len, convert) {
-  var keys = GetSortedArrayKeys(array, %GetArrayKeys(array, len));
-  var last_key = -1;
+function SparseJoin(array, keys, convert) {
   var keys_length = keys.length;
-
   var elements = new InternalArray(keys_length);
-  var elements_length = 0;
-
   for (var i = 0; i < keys_length; i++) {
-    var key = keys[i];
-    if (key != last_key) {
-      var e = array[key];
-      if (!IS_STRING(e)) e = convert(e);
-      elements[elements_length++] = e;
-      last_key = key;
+    var e = array[keys[i]];
+    elements[i] = IS_STRING(e) ? e : convert(e);
   }
-  }
-  return %StringBuilderConcat(elements, elements_length, '');
+  return %StringBuilderConcat(elements, keys_length, '');
 }
 
 
@@ -167,98 +135,122 @@ function UseSparseVariant(array, length, is_array, touched) {
     (touched > estimated_elements * 4);
 }
 
+function Stack() {
+  this.length = 0;
+  this.values = new InternalArray();
+}
 
-function Join(array, length, separator, convert) {
-  if (length == 0) return '';
+// Predeclare the instance variables on the prototype. Otherwise setting them in
+// the constructor will leak the instance through settings on Object.prototype.
+Stack.prototype.length = null;
+Stack.prototype.values = null;
 
-  var is_array = IS_ARRAY(array);
+function StackPush(stack, value) {
+  stack.values[stack.length++] = value;
+}
 
-  if (is_array) {
-    // If the array is cyclic, return the empty string for already
-    // visited arrays.
-    if (!%PushIfAbsent(visited_arrays, array)) return '';
+function StackPop(stack) {
+  stack.values[--stack.length] = null
+}
+
+function StackHas(stack, v) {
+  var length = stack.length;
+  var values = stack.values;
+  for (var i = 0; i < length; i++) {
+    if (values[i] === v) return true;
   }
+  return false;
+}
 
-  // Attempt to convert the elements.
-  try {
+// Global list of arrays visited during toString, toLocaleString and
+// join invocations.
+var visited_arrays = new Stack();
+
+function DoJoin(array, length, is_array, separator, convert) {
   if (UseSparseVariant(array, length, is_array, length)) {
     %NormalizeElements(array);
-      if (separator.length == 0) {
-        return SparseJoin(array, length, convert);
+    var keys = GetSortedArrayKeys(array, %GetArrayKeys(array, length));
+    if (separator === '') {
+      if (keys.length === 0) return '';
+      return SparseJoin(array, keys, convert);
     } else {
-        return SparseJoinWithSeparatorJS(array, length, convert, separator);
+      return SparseJoinWithSeparatorJS(array, keys, length, convert, separator);
     }
   }
 
   // Fast case for one-element arrays.
-    if (length == 1) {
+  if (length === 1) {
     var e = array[0];
-      if (IS_STRING(e)) return e;
-      return convert(e);
+    return IS_STRING(e) ? e : convert(e);
   }
 
   // Construct an array for the elements.
   var elements = new InternalArray(length);
 
   // We pull the empty separator check outside the loop for speed!
-    if (separator.length == 0) {
-      var elements_length = 0;
+  if (separator === '') {
     for (var i = 0; i < length; i++) {
       var e = array[i];
-        if (!IS_STRING(e)) e = convert(e);
-        elements[elements_length++] = e;
+      elements[i] = IS_STRING(e) ? e : convert(e);
     }
-      elements.length = elements_length;
-      return %StringBuilderConcat(elements, elements_length, '');
+    return %StringBuilderConcat(elements, length, '');
   }
   // Non-empty separator case.
   // If the first element is a number then use the heuristic that the
   // remaining elements are also likely to be numbers.
   var e = array[0];
-    if (!IS_NUMBER(e)) {
-      if (!IS_STRING(e)) e = convert(e);
-      elements[0] = e;
+  if (IS_NUMBER(e)) {
+    elements[0] = %_NumberToString(e);
     for (var i = 1; i < length; i++) {
       e = array[i];
-        if (!IS_STRING(e)) e = convert(e);
-        elements[i] = e;
+      if (IS_NUMBER(e)) {
+        elements[i] = %_NumberToString(e);
+      } else {
+        elements[i] = IS_STRING(e) ? e : convert(e);
+      }
     }
   } else {
-      elements[0] = %_NumberToString(e);
+    elements[0] = IS_STRING(e) ? e : convert(e);
     for (var i = 1; i < length; i++) {
       e = array[i];
-        if (IS_NUMBER(e)) {
-          e = %_NumberToString(e);
-        } else if (!IS_STRING(e)) {
-          e = convert(e);
-        }
-        elements[i] = e;
+      elements[i] = IS_STRING(e) ? e : convert(e);
     }
   }
   return %StringBuilderJoin(elements, length, separator);
+}
+
+function Join(array, length, separator, convert) {
+  if (length === 0) return '';
+
+  var is_array = IS_ARRAY(array);
+
+  if (is_array) {
+    // If the array is cyclic, return the empty string for already
+    // visited arrays.
+    if (StackHas(visited_arrays, array)) return '';
+    StackPush(visited_arrays, array);
+  }
+
+  // Attempt to convert the elements.
+  try {
+    return DoJoin(array, length, is_array, separator, convert);
   } finally {
     // Make sure to remove the last element of the visited array no
     // matter what happens.
-    if (is_array) visited_arrays.length = visited_arrays.length - 1;
+    if (is_array) StackPop(visited_arrays);
   }
 }
 
 
 function ConvertToString(x) {
-  if (IS_NULL_OR_UNDEFINED(x)) {
-    return '';
-  } else {
+  if (IS_NULL_OR_UNDEFINED(x)) return '';
   return TO_STRING(x);
-  }
 }
 
 
 function ConvertToLocaleString(e) {
-  if (IS_NULL_OR_UNDEFINED(e)) {
-    return '';
-  } else {
+  if (IS_NULL_OR_UNDEFINED(e)) return '';
   return TO_STRING(e.toLocaleString());
-  }
 }
 
 
@@ -1959,6 +1951,10 @@ utils.Export(function(to) {
   to.InnerArraySort = InnerArraySort;
   to.InnerArrayToLocaleString = InnerArrayToLocaleString;
   to.PackedArrayReverse = PackedArrayReverse;
+  to.Stack = Stack;
+  to.StackHas = StackHas;
+  to.StackPush = StackPush;
+  to.StackPop = StackPop;
 });
 
 %InstallToContext([

src/js/json.js

@@ -19,6 +19,10 @@ var MakeTypeError;
 var MaxSimple;
 var MinSimple;
 var ObjectHasOwnProperty;
+var Stack;
+var StackHas;
+var StackPop;
+var StackPush;
 var toStringTagSymbol = utils.ImportNow("to_string_tag_symbol");
 
 utils.Import(function(from) {
@@ -26,6 +30,10 @@ utils.Import(function(from) {
   MaxSimple = from.MaxSimple;
   MinSimple = from.MinSimple;
   ObjectHasOwnProperty = from.ObjectHasOwnProperty;
+  Stack = from.Stack;
+  StackHas = from.StackHas;
+  StackPop = from.StackPop;
+  StackPush = from.StackPush;
 });
 
 // -------------------------------------------------------------------
@@ -78,7 +86,8 @@ function JSONParse(text, reviver) {
 
 
 function SerializeArray(value, replacer, stack, indent, gap) {
-  if (!%PushIfAbsent(stack, value)) throw MakeTypeError(kCircularStructure);
+  if (StackHas(stack, value)) throw MakeTypeError(kCircularStructure);
+  StackPush(stack, value);
   var stepback = indent;
   indent += gap;
   var partial = new InternalArray();
@@ -101,13 +110,14 @@ function SerializeArray(value, replacer, stack, indent, gap) {
   } else {
     final = "[]";
   }
-  stack.pop();
+  StackPop(stack);
   return final;
 }
 
 
 function SerializeObject(value, replacer, stack, indent, gap) {
-  if (!%PushIfAbsent(stack, value)) throw MakeTypeError(kCircularStructure);
+  if (StackHas(stack, value)) throw MakeTypeError(kCircularStructure);
+  StackPush(stack, value);
   var stepback = indent;
   indent += gap;
   var partial = new InternalArray();
@@ -146,7 +156,7 @@ function SerializeObject(value, replacer, stack, indent, gap) {
   } else {
     final = "{}";
   }
-  stack.pop();
+  StackPop(stack);
   return final;
 }
 
@@ -241,7 +251,7 @@ function JSONStringify(value, replacer, space) {
   if (!IS_CALLABLE(replacer) && !property_list && !gap && !IS_PROXY(value)) {
     return %BasicJSONStringify(value);
   }
-  return JSONSerialize('', {'': value}, replacer, new InternalArray(), "", gap);
+  return JSONSerialize('', {'': value}, replacer, new Stack(), "", gap);
 }
 
 // -------------------------------------------------------------------
@@ -279,7 +289,7 @@ function JsonSerializeAdapter(key, object) {
   var holder = {};
   holder[key] = object;
   // No need to pass the actual holder since there is no replacer function.
-  return JSONSerialize(key, holder, UNDEFINED, new InternalArray(), "", "");
+  return JSONSerialize(key, holder, UNDEFINED, new Stack(), "", "");
 }
 
 %InstallToContext(["json_serialize_adapter", JsonSerializeAdapter]);

src/objects.cc

@@ -17482,9 +17482,6 @@ template Handle<NameDictionary>
 Dictionary<NameDictionary, NameDictionaryShape, Handle<Name> >::
     EnsureCapacity(Handle<NameDictionary>, int, Handle<Name>);
 
-template bool Dictionary<SeededNumberDictionary, SeededNumberDictionaryShape,
-                         uint32_t>::HasComplexElements();
-
 template int HashTable<SeededNumberDictionary, SeededNumberDictionaryShape,
                        uint32_t>::FindEntry(uint32_t);
 
@@ -18325,6 +18322,21 @@ void Dictionary<Derived, Shape, Key>::AddEntry(
   dictionary->ElementAdded();
 }
 
+bool SeededNumberDictionary::HasComplexElements() {
+  if (!requires_slow_elements()) return false;
+  int capacity = this->Capacity();
+  for (int i = 0; i < capacity; i++) {
+    Object* k = this->KeyAt(i);
+    if (this->IsKey(k)) {
+      DCHECK(!IsDeleted(i));
+      PropertyDetails details = this->DetailsAt(i);
+      if (details.type() == ACCESSOR_CONSTANT) return true;
+      PropertyAttributes attr = details.attributes();
+      if (attr & ALL_ATTRIBUTES_MASK) return true;
+    }
+  }
+  return false;
+}
 
 void SeededNumberDictionary::UpdateMaxNumberKey(uint32_t key,
                                                 bool used_as_prototype) {
@@ -18432,23 +18444,6 @@ int Dictionary<Derived, Shape, Key>::NumberOfElementsFilterAttributes(
 }
 
 
-template <typename Derived, typename Shape, typename Key>
-bool Dictionary<Derived, Shape, Key>::HasComplexElements() {
-  int capacity = this->Capacity();
-  for (int i = 0; i < capacity; i++) {
-    Object* k = this->KeyAt(i);
-    if (this->IsKey(k) && !k->FilterKey(ALL_PROPERTIES)) {
-      if (this->IsDeleted(i)) continue;
-      PropertyDetails details = this->DetailsAt(i);
-      if (details.type() == ACCESSOR_CONSTANT) return true;
-      PropertyAttributes attr = details.attributes();
-      if (attr & ALL_ATTRIBUTES_MASK) return true;
-    }
-  }
-  return false;
-}
-
-
 template <typename Dictionary>
 struct EnumIndexComparator {
   explicit EnumIndexComparator(Dictionary* dict) : dict(dict) {}

src/objects.h

@@ -3485,10 +3485,6 @@ class Dictionary: public HashTable<Derived, Shape, Key> {
     return NumberOfElementsFilterAttributes(ENUMERABLE_STRINGS);
   }
 
-  // Returns true if the dictionary contains any elements that are non-writable,
-  // non-configurable, non-enumerable, or have getters/setters.
-  bool HasComplexElements();
-
   enum SortMode { UNSORTED, SORTED };
 
   // Fill in details for properties into storage.
@@ -3721,6 +3717,10 @@ class SeededNumberDictionary
 
   void UpdateMaxNumberKey(uint32_t key, bool used_as_prototype);
 
+  // Returns true if the dictionary contains any elements that are non-writable,
+  // non-configurable, non-enumerable, or have getters/setters.
+  bool HasComplexElements();
+
   // If slow elements are required we will never go back to fast-case
   // for the elements kept in this dictionary.  We require slow
   // elements if an element has been added at an index larger than

src/runtime/runtime-array.cc

@@ -88,29 +88,6 @@ RUNTIME_FUNCTION(Runtime_TransitionElementsKind) {
 }
 
 
-// Push an object unto an array of objects if it is not already in the
-// array.  Returns true if the element was pushed on the stack and
-// false otherwise.
-RUNTIME_FUNCTION(Runtime_PushIfAbsent) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
-  CONVERT_ARG_HANDLE_CHECKED(JSArray, array, 0);
-  CONVERT_ARG_HANDLE_CHECKED(JSReceiver, element, 1);
-  RUNTIME_ASSERT(array->HasFastSmiOrObjectElements());
-  int length = Smi::cast(array->length())->value();
-  FixedArray* elements = FixedArray::cast(array->elements());
-  for (int i = 0; i < length; i++) {
-    if (elements->get(i) == *element) return isolate->heap()->false_value();
-  }
-
-  // Strict not needed. Used for cycle detection in Array join implementation.
-  RETURN_FAILURE_ON_EXCEPTION(
-      isolate, JSObject::AddDataElement(array, length, element, NONE));
-  JSObject::ValidateElements(array);
-  return isolate->heap()->true_value();
-}
-
-
 // Moves all own elements of an object, that are below a limit, to positions
 // starting at zero. All undefined values are placed after non-undefined values,
 // and are followed by non-existing element. Does not change the length

src/runtime/runtime-strings.cc

@@ -642,13 +642,6 @@ RUNTIME_FUNCTION(Runtime_SparseJoinWithSeparator) {
   RUNTIME_ASSERT(elements_length <= elements_array->elements()->length());
   RUNTIME_ASSERT((elements_length & 1) == 0);  // Even length.
   FixedArray* elements = FixedArray::cast(elements_array->elements());
-  for (int i = 0; i < elements_length; i += 2) {
-    RUNTIME_ASSERT(elements->get(i)->IsNumber());
-    CONVERT_NUMBER_CHECKED(uint32_t, position, Uint32, elements->get(i));
-    RUNTIME_ASSERT(position < array_length);
-    RUNTIME_ASSERT(elements->get(i + 1)->IsString());
-  }
-
   {
     DisallowHeapAllocation no_gc;
     for (int i = 0; i < elements_length; i += 2) {

src/runtime/runtime.h

@@ -35,7 +35,6 @@ namespace internal {
   F(FinishArrayPrototypeSetup, 1, 1) \
   F(SpecialArrayFunctions, 0, 1)     \
   F(TransitionElementsKind, 2, 1)    \
-  F(PushIfAbsent, 2, 1)              \
   F(RemoveArrayHoles, 2, 1)          \
   F(MoveArrayContents, 2, 1)         \
   F(EstimateNumberOfElements, 1, 1)  \

test/mjsunit/json-stringify-stack.js

+// Copyright 2016 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.
+
+Object.defineProperty(Object.prototype, "length", {set() { throw "error" }});
+Object.defineProperty(Object.prototype, "values", {set() { throw "error" }});
+
+JSON.stringify({}, v=>v);