Create optimized versions of the Map/Set clear method

src/objects.cc

 // Copyright 2013 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.
 
 #include <sstream>
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/allocation-site-scopes.h"
@@ skipping 15970 matching lines @@
 Handle<Derived> OrderedHashTable<Derived, Iterator, entrysize>::Clear(
     Handle<Derived> table) {
   DCHECK(!table->IsObsolete());
 
   Handle<Derived> new_table =
       Allocate(table->GetIsolate(),
                kMinCapacity,
                table->GetHeap()->InNewSpace(*table) ? NOT_TENURED : TENURED);
 
   table->SetNextTable(*new_table);
-  table->SetNumberOfDeletedElements(-1);
+  table->SetNumberOfDeletedElements(kClearedTableSentinel);
 
   return new_table;
 }
 
 
 template<class Derived, class Iterator, int entrysize>
 Handle<Derived> OrderedHashTable<Derived, Iterator, entrysize>::Remove(
     Handle<Derived> table, Handle<Object> key, bool* was_present) {
   int entry = table->FindEntry(key);
   if (entry == kNotFound) {
@@ skipping 224 matching lines @@
   TableType* table = TableType::cast(this->table());
   if (!table->IsObsolete()) return;
 
   int index = Smi::cast(this->index())->value();
   while (table->IsObsolete()) {
     TableType* next_table = table->NextTable();
 
     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;
         for (int i = 0; i < nod; ++i) {
           int removed_index = table->RemovedIndexAt(i);
           if (removed_index >= old_index) break;
           --index;
         }
       }
     }
@@ skipping 647 matching lines @@
   Handle<DependentCode> codes =
       DependentCode::Insert(handle(cell->dependent_code(), info->isolate()),
                             DependentCode::kPropertyCellChangedGroup,
                             info->object_wrapper());
   if (*codes != cell->dependent_code()) cell->set_dependent_code(*codes);
   info->dependencies(DependentCode::kPropertyCellChangedGroup)->Add(
       cell, info->zone());
 }
 
 } }  // namespace v8::internal