Create optimized versions of the Map/Set clear method

This completes the first round of optimizations for Map and Set.
All non-key-dependent methods now have a Hydrogen version, and
for keyed methods, string versions are optimized.

Review URL: https://codereview.chromium.org/796503002

Cr-Commit-Position: refs/heads/master@{#25763}

src/collection.js

@@ -92,7 +92,7 @@ function SetClearJS() {
     throw MakeTypeError('incompatible_method_receiver',
                         ['Set.prototype.clear', this]);
   }
-  %SetClear(this);
+  %_SetClear(this);
 }
 
 
@@ -245,7 +245,7 @@ function MapClearJS() {
     throw MakeTypeError('incompatible_method_receiver',
                         ['Map.prototype.clear', this]);
   }
-  %MapClear(this);
+  %_MapClear(this);
 }
 
 

src/hydrogen-instructions.h

@@ -6367,6 +6367,11 @@ class HObjectAccess FINAL {
                          Representation::Smi());
   }
 
+  template <typename CollectionType>
+  static HObjectAccess ForOrderedHashTableNextTable() {
+    return HObjectAccess(kInobject, CollectionType::kNextTableOffset);
+  }
+
   template <typename CollectionType>
   static HObjectAccess ForOrderedHashTableBucket(int bucket) {
     return HObjectAccess(kInobject, CollectionType::kHashTableStartOffset +

src/hydrogen.cc

@@ -12727,6 +12727,46 @@ void HOptimizedGraphBuilder::GenerateMapInitialize(CallRuntime* call) {
 }
 
 
+template <typename CollectionType>
+void HOptimizedGraphBuilder::BuildOrderedHashTableClear(HValue* receiver) {
+  HValue* old_table =
+      Add<HLoadNamedField>(receiver, static_cast<HValue*>(NULL),
+                           HObjectAccess::ForJSCollectionTable());
+  HValue* new_table = BuildAllocateOrderedHashTable<CollectionType>();
+  Add<HStoreNamedField>(
+      old_table, HObjectAccess::ForOrderedHashTableNextTable<CollectionType>(),
+      new_table);
+  Add<HStoreNamedField>(
+      old_table, HObjectAccess::ForOrderedHashTableNumberOfDeletedElements<
+                     CollectionType>(),
+      Add<HConstant>(CollectionType::kClearedTableSentinel));
+  Add<HStoreNamedField>(receiver, HObjectAccess::ForJSCollectionTable(),
+                        new_table);
+}
+
+
+void HOptimizedGraphBuilder::GenerateSetClear(CallRuntime* call) {
+  DCHECK(call->arguments()->length() == 1);
+  CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
+  HValue* receiver = Pop();
+
+  NoObservableSideEffectsScope no_effects(this);
+  BuildOrderedHashTableClear<OrderedHashSet>(receiver);
+  return ast_context()->ReturnValue(graph()->GetConstantUndefined());
+}
+
+
+void HOptimizedGraphBuilder::GenerateMapClear(CallRuntime* call) {
+  DCHECK(call->arguments()->length() == 1);
+  CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
+  HValue* receiver = Pop();
+
+  NoObservableSideEffectsScope no_effects(this);
+  BuildOrderedHashTableClear<OrderedHashMap>(receiver);
+  return ast_context()->ReturnValue(graph()->GetConstantUndefined());
+}
+
+
 void HOptimizedGraphBuilder::GenerateGetCachedArrayIndex(CallRuntime* call) {
   DCHECK(call->arguments()->length() == 1);
   CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));

src/hydrogen.h

@@ -2434,6 +2434,8 @@ class HOptimizedGraphBuilder : public HGraphBuilder, public AstVisitor {
   template <typename CollectionType>
   HValue* BuildAllocateOrderedHashTable();
   template <typename CollectionType>
+  void BuildOrderedHashTableClear(HValue* receiver);
+  template <typename CollectionType>
   void BuildJSCollectionDelete(CallRuntime* call,
                                const Runtime::Function* c_function);
   template <typename CollectionType>

src/objects.cc

@@ -16025,7 +16025,7 @@ Handle<Derived> OrderedHashTable<Derived, Iterator, entrysize>::Clear(
                table->GetHeap()->InNewSpace(*table) ? NOT_TENURED : TENURED);
 
   table->SetNextTable(*new_table);
-  table->SetNumberOfDeletedElements(-1);
+  table->SetNumberOfDeletedElements(kClearedTableSentinel);
 
   return new_table;
 }
@@ -16270,8 +16270,7 @@ void OrderedHashTableIterator<Derived, TableType>::Transition() {
     if (index > 0) {
       int nod = table->NumberOfDeletedElements();
 
-      // When we clear the table we set the number of deleted elements to -1.
-      if (nod == -1) {
+      if (nod == TableType::kClearedTableSentinel) {
         index = 0;
       } else {
         int old_index = index;

src/objects.h

@@ -3933,6 +3933,7 @@ class OrderedHashTable: public FixedArray {
   static const int kNumberOfElementsIndex = kNumberOfBucketsIndex + 1;
   static const int kNumberOfDeletedElementsIndex = kNumberOfElementsIndex + 1;
   static const int kHashTableStartIndex = kNumberOfDeletedElementsIndex + 1;
+  static const int kNextTableIndex = kNumberOfElementsIndex;
 
   static const int kNumberOfBucketsOffset =
       kHeaderSize + kNumberOfBucketsIndex * kPointerSize;
@@ -3942,12 +3943,19 @@ class OrderedHashTable: public FixedArray {
       kHeaderSize + kNumberOfDeletedElementsIndex * kPointerSize;
   static const int kHashTableStartOffset =
       kHeaderSize + kHashTableStartIndex * kPointerSize;
+  static const int kNextTableOffset =
+      kHeaderSize + kNextTableIndex * kPointerSize;
 
   static const int kEntrySize = entrysize + 1;
   static const int kChainOffset = entrysize;
 
   static const int kLoadFactor = 2;
 
+  // NumberOfDeletedElements is set to kClearedTableSentinel when
+  // the table is cleared, which allows iterator transitions to
+  // optimize that case.
+  static const int kClearedTableSentinel = -1;
+
  private:
   static Handle<Derived> Rehash(Handle<Derived> table, int new_capacity);
 
@@ -3989,7 +3997,6 @@ class OrderedHashTable: public FixedArray {
     return set(kRemovedHolesIndex + index, Smi::FromInt(removed_index));
   }
 
-  static const int kNextTableIndex = kNumberOfElementsIndex;
   static const int kRemovedHolesIndex = kHashTableStartIndex;
 
   static const int kMaxCapacity =

src/runtime/runtime.h

@@ -300,17 +300,11 @@ namespace internal {
   F(GetConstructTrap, 1, 1)                            \
   F(Fix, 1, 1)                                         \
                                                        \
-  /* Harmony sets */                                   \
-  F(SetClear, 1, 1)                                    \
-                                                       \
+  /* ES6 collection iterators */                       \
   F(SetIteratorInitialize, 3, 1)                       \
   F(SetIteratorClone, 1, 1)                            \
   F(SetIteratorNext, 2, 1)                             \
   F(SetIteratorDetails, 1, 1)                          \
-                                                       \
-  /* Harmony maps */                                   \
-  F(MapClear, 1, 1)                                    \
-                                                       \
   F(MapIteratorInitialize, 3, 1)                       \
   F(MapIteratorClone, 1, 1)                            \
   F(MapIteratorNext, 2, 1)                             \
@@ -721,6 +715,7 @@ namespace internal {
   F(MathSqrtRT, 1, 1)                     \
   F(MathLogRT, 1, 1)                      \
   /* ES6 Collections */                   \
+  F(MapClear, 1, 1)                       \
   F(MapDelete, 2, 1)                      \
   F(MapGet, 2, 1)                         \
   F(MapGetSize, 1, 1)                     \
@@ -728,6 +723,7 @@ namespace internal {
   F(MapInitialize, 1, 1)                  \
   F(MapSet, 3, 1)                         \
   F(SetAdd, 2, 1)                         \
+  F(SetClear, 1, 1)                       \
   F(SetDelete, 2, 1)                      \
   F(SetGetSize, 1, 1)                     \
   F(SetHas, 2, 1)                         \