Replace uint64_t type with ObjectId and use uint32_t as the base for ObjectId type.

src/profile-generator.h

Index: src/profile-generator.h
diff --git a/src/profile-generator.h b/src/profile-generator.h
index f9ae5f9d26bd5b66ff7fda38312654e5ed8073b2..ba617f9e40be969fc27c7a260c158cea849798bd 100644
--- a/src/profile-generator.h
+++ b/src/profile-generator.h
@@ -35,6 +35,8 @@
 namespace v8 {
 namespace internal {
 
+typedef uint32_t SnapshotObjectId;
+
 class TokenEnumerator {
  public:
   TokenEnumerator();
@@ -533,7 +535,7 @@ class HeapEntry BASE_EMBEDDED {
   void Init(HeapSnapshot* snapshot,
             Type type,
             const char* name,
-            uint64_t id,
+            SnapshotObjectId id,
             int self_size,
             int children_count,
             int retainers_count);
@@ -542,7 +544,7 @@ class HeapEntry BASE_EMBEDDED {
   Type type() { return static_cast<Type>(type_); }
   const char* name() { return name_; }
   void set_name(const char* name) { name_ = name; }
-  inline uint64_t id();
+  inline SnapshotObjectId id();
   int self_size() { return self_size_; }
   int retained_size() { return retained_size_; }
   void add_retained_size(int size) { retained_size_ += size; }
@@ -651,7 +653,7 @@ class HeapSnapshot {
       int entries_count, int children_count, int retainers_count);
   HeapEntry* AddEntry(HeapEntry::Type type,
                       const char* name,
-                      uint64_t id,
+                      SnapshotObjectId id,
                       int size,
                       int children_count,
                       int retainers_count);
@@ -662,7 +664,7 @@ class HeapSnapshot {
                                int retainers_count);
   HeapEntry* AddNativesRootEntry(int children_count, int retainers_count);
   void ClearPaint();
-  HeapEntry* GetEntryById(uint64_t id);
+  HeapEntry* GetEntryById(SnapshotObjectId id);
   List<HeapEntry*>* GetSortedEntriesList();
   template<class Visitor>
   void IterateEntries(Visitor* visitor) { entries_.Iterate(visitor); }
@@ -699,29 +701,29 @@ class HeapObjectsMap {
   ~HeapObjectsMap();
 
   void SnapshotGenerationFinished();
-  uint64_t FindObject(Address addr);
+  SnapshotObjectId FindObject(Address addr);
   void MoveObject(Address from, Address to);
 
-  static uint64_t GenerateId(v8::RetainedObjectInfo* info);
-  static inline uint64_t GetNthGcSubrootId(int delta);
+  static SnapshotObjectId GenerateId(v8::RetainedObjectInfo* info);
+  static inline SnapshotObjectId GetNthGcSubrootId(int delta);
 
   static const int kObjectIdStep = 2;
-  static const uint64_t kInternalRootObjectId;
-  static const uint64_t kGcRootsObjectId;
-  static const uint64_t kNativesRootObjectId;
-  static const uint64_t kGcRootsFirstSubrootId;
-  static const uint64_t kFirstAvailableObjectId;
+  static const SnapshotObjectId kInternalRootObjectId;
+  static const SnapshotObjectId kGcRootsObjectId;
+  static const SnapshotObjectId kNativesRootObjectId;
+  static const SnapshotObjectId kGcRootsFirstSubrootId;
+  static const SnapshotObjectId kFirstAvailableObjectId;
 
  private:
   struct EntryInfo {
-    explicit EntryInfo(uint64_t id) : id(id), accessed(true) { }
-    EntryInfo(uint64_t id, bool accessed) : id(id), accessed(accessed) { }
-    uint64_t id;
+    explicit EntryInfo(SnapshotObjectId id) : id(id), accessed(true) { }
+    EntryInfo(SnapshotObjectId id, bool accessed) : id(id), accessed(accessed) { }
+    SnapshotObjectId id;
     bool accessed;
   };
 
-  void AddEntry(Address addr, uint64_t id);
-  uint64_t FindEntry(Address addr);
+  void AddEntry(Address addr, SnapshotObjectId id);
+  SnapshotObjectId FindEntry(Address addr);
   void RemoveDeadEntries();
 
   static bool AddressesMatch(void* key1, void* key2) {
@@ -735,7 +737,7 @@ class HeapObjectsMap {
   }
 
   bool initial_fill_mode_;
-  uint64_t next_id_;
+  SnapshotObjectId next_id_;
   HashMap entries_map_;
   List<EntryInfo>* entries_;
 
@@ -760,8 +762,8 @@ class HeapSnapshotsCollection {
   StringsStorage* names() { return &names_; }
   TokenEnumerator* token_enumerator() { return token_enumerator_; }
 
-  uint64_t GetObjectId(Address addr) { return ids_.FindObject(addr); }
-  Handle<HeapObject> FindHeapObjectById(uint64_t id);
+  SnapshotObjectId GetObjectId(Address addr) { return ids_.FindObject(addr); }
+  Handle<HeapObject> FindHeapObjectById(SnapshotObjectId id);
   void ObjectMoveEvent(Address from, Address to) { ids_.MoveObject(from, to); }
 
  private: