[heap] Move IdentityMap data structure out of heap.

src/heap/identity-map.h

-// Copyright 2015 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_HEAP_IDENTITY_MAP_H_
-#define V8_HEAP_IDENTITY_MAP_H_
-
-#include "src/handles.h"
-
-namespace v8 {
-namespace internal {
-
-// Forward declarations.
-class Heap;
-class Zone;
-
-// Base class of identity maps contains shared code for all template
-// instantions.
-class IdentityMapBase {
- public:
-  // Enable or disable concurrent mode for this map. Concurrent mode implies
-  // taking the heap's relocation lock during most operations.
-  void SetConcurrent(bool concurrent) { concurrent_ = concurrent; }
-
- protected:
-  // Allow Tester to access internals, including changing the address of objects
-  // within the {keys_} array in order to simulate a moving GC.
-  friend class IdentityMapTester;
-
-  typedef void** RawEntry;
-
-  IdentityMapBase(Heap* heap, Zone* zone)
-      : heap_(heap),
-        zone_(zone),
-        concurrent_(false),
-        gc_counter_(-1),
-        size_(0),
-        mask_(0),
-        keys_(nullptr),
-        values_(nullptr) {}
-  ~IdentityMapBase();
-
-  RawEntry GetEntry(Handle<Object> key);
-  RawEntry FindEntry(Handle<Object> key);
-
- private:
-  // Internal implementation should not be called directly by subclasses.
-  int LookupIndex(Object* address);
-  int InsertIndex(Object* address);
-  void Rehash();
-  void Resize();
-  RawEntry Lookup(Handle<Object> key);
-  RawEntry Insert(Handle<Object> key);
-  int Hash(Object* address);
-
-  Heap* heap_;
-  Zone* zone_;
-  bool concurrent_;
-  int gc_counter_;
-  int size_;
-  int mask_;
-  Object** keys_;
-  void** values_;
-};
-
-// Implements an identity map from object addresses to a given value type {V}.
-// The map is robust w.r.t. garbage collection by synchronization with the
-// supplied {heap}.
-//  * Keys are treated as strong roots.
-//  * SMIs are valid keys, except SMI #0.
-//  * The value type {V} must be reinterpret_cast'able to {void*}
-//  * The value type {V} must not be a heap type.
-template <typename V>
-class IdentityMap : public IdentityMapBase {
- public:
-  IdentityMap(Heap* heap, Zone* zone) : IdentityMapBase(heap, zone) {}
-
-  // Searches this map for the given key using the object's address
-  // as the identity, returning:
-  //    found => a pointer to the storage location for the value
-  //    not found => a pointer to a new storage location for the value
-  V* Get(Handle<Object> key) { return reinterpret_cast<V*>(GetEntry(key)); }
-
-  // Searches this map for the given key using the object's address
-  // as the identity, returning:
-  //    found => a pointer to the storage location for the value
-  //    not found => {nullptr}
-  V* Find(Handle<Object> key) { return reinterpret_cast<V*>(FindEntry(key)); }
-
-  // Set the value for the given key.
-  void Set(Handle<Object> key, V value) {
-    *(reinterpret_cast<V*>(GetEntry(key))) = value;
-  }
-};
-}
-}  // namespace v8::internal
-
-#endif  // V8_HEAP_IDENTITY_MAP_H_