Add dump_symbol_stats to dump symbol table stats at the end of a test run

vm/symbols.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_SYMBOLS_H_
 #define VM_SYMBOLS_H_
 
 #include "vm/object.h"
 #include "vm/snapshot_ids.h"
 
@@ skipping 208 matching lines @@
   static const char* Name(SymbolId symbol);
 
   static RawString* FromCharCode(int32_t char_code);
 
   static RawString** PredefinedAddress() {
     return reinterpret_cast<RawString**>(&predefined_);
   }
 
   static bool IsPredefinedHandle(uword address);
 
+  static void DumpStats();
+
  private:
   enum {
-    kInitialVMIsolateSymtabSize = ((kMaxId + 15) & -16),
-    kInitialSymtabSize = 256
+    kInitialVMIsolateSymtabSize = 512,
+    kInitialSymtabSize = 2048
   };
 
   // Helper functions to create a symbol given a string or set of characters.
   template<typename CharacterType, typename CallbackType>
   static RawString* NewSymbol(const CharacterType* characters,
                               intptr_t len,
                               CallbackType new_string);
 
   // Add the string into the VM isolate symbol table.
   static void Add(const Array& symbol_table, const String& str);
@@ skipping 25 matching lines @@
             object_id < (kMaxPredefinedObjectIds + kMaxId));
   }
 
   // List of symbols that are stored in the vm isolate for easy access.
   static RawString* predefined_[kMaxId];
 
   // Structure for managing handles allocation for symbols that are
   // stored in the vm isolate.
   static VMHandles predefined_handles_;
 
+  // Statistics used to measure the efficiency of the symbol table.
+  static const intptr_t kMaxCollisionBuckets = 10;
+  static intptr_t num_of_grows_;
+  static intptr_t collision_count_[kMaxCollisionBuckets];
+
 #define DECLARE_SYMBOL_HANDLE(symbol)                                          \
   static String* symbol##_handle_;
 PREDEFINED_SYMBOL_HANDLES_LIST(DECLARE_SYMBOL_HANDLE)
 #undef DECLARE_SYMBOL_HANDLE
 
   friend class String;
   friend class SnapshotReader;
   friend class SnapshotWriter;
   friend class ApiMessageReader;
 
   DISALLOW_COPY_AND_ASSIGN(Symbols);
 };
 
 }  // namespace dart
 
 #endif  // VM_SYMBOLS_H_