Optimize non-mutation Map and Set operations for String keys

src/objects.h

 // 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.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 3883 matching lines @@
   }
 
   // When the table is obsolete we store the indexes of the removed holes.
   int RemovedIndexAt(int index) {
     return Smi::cast(get(kRemovedHolesIndex + index))->value();
   }
 
   static const int kNotFound = -1;
   static const int kMinCapacity = 4;
 
+  static const int kNumberOfBucketsIndex = 0;
+  static const int kNumberOfElementsIndex = kNumberOfBucketsIndex + 1;
+  static const int kNumberOfDeletedElementsIndex = kNumberOfElementsIndex + 1;
+  static const int kHashTableStartIndex = kNumberOfDeletedElementsIndex + 1;
+
+  static const int kNumberOfBucketsOffset =
+      kHeaderSize + kNumberOfBucketsIndex * kPointerSize;
+  static const int kNumberOfElementsOffset =
+      kHeaderSize + kNumberOfElementsIndex * kPointerSize;
+
+  static const int kEntrySize = entrysize + 1;
+  static const int kChainOffset = entrysize;
+
  private:
   static Handle<Derived> Rehash(Handle<Derived> table, int new_capacity);
 
   void SetNumberOfBuckets(int num) {
     set(kNumberOfBucketsIndex, Smi::FromInt(num));
   }
 
   void SetNumberOfElements(int num) {
     set(kNumberOfElementsIndex, Smi::FromInt(num));
   }
@@ skipping 21 matching lines @@
   }
 
   void SetNextTable(Derived* next_table) {
     set(kNextTableIndex, next_table);
   }
 
   void SetRemovedIndexAt(int index, int removed_index) {
     return set(kRemovedHolesIndex + index, Smi::FromInt(removed_index));
   }
 
-  static const int kNumberOfBucketsIndex = 0;
-  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 kRemovedHolesIndex = kHashTableStartIndex;
 
-  static const int kEntrySize = entrysize + 1;
-  static const int kChainOffset = entrysize;
-
   static const int kLoadFactor = 2;
   static const int kMaxCapacity =
       (FixedArray::kMaxLength - kHashTableStartIndex)
       / (1 + (kEntrySize * kLoadFactor));
 };
 
 
 class JSSetIterator;
 
 
@@ skipping 19 matching lines @@
   Object* Lookup(Handle<Object> key);
   static Handle<OrderedHashMap> Put(
       Handle<OrderedHashMap> table,
       Handle<Object> key,
       Handle<Object> value);
 
   Object* ValueAt(int entry) {
     return get(EntryToIndex(entry) + kValueOffset);
   }
 
- private:
   static const int kValueOffset = 1;
 };
 
 
 template <int entrysize>
 class WeakHashTableShape : public BaseShape<Handle<Object> > {
  public:
   static inline bool IsMatch(Handle<Object> key, Object* other);
   static inline uint32_t Hash(Handle<Object> key);
   static inline uint32_t HashForObject(Handle<Object> key, Object* object);
@@ skipping 6973 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_