Add usage and collision details to the hash table data structure in order to determine effectivenes…

runtime/vm/precompiler.h

 // Copyright (c) 2015, 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_PRECOMPILER_H_
 #define VM_PRECOMPILER_H_
 
 #include "vm/allocation.h"
 #include "vm/hash_map.h"
 #include "vm/hash_table.h"
@@ skipping 355 matching lines @@
   TypeArgumentsSet typeargs_to_retain_;
   AbstractTypeSet types_to_retain_;
   InstanceSet consts_to_retain_;
   Error& error_;
 };
 
 
 class FunctionsTraits {
  public:
   static const char* Name() { return "FunctionsTraits"; }
+  static bool ReportStats() { return false; }
 
   static bool IsMatch(const Object& a, const Object& b) {
     Zone* zone = Thread::Current()->zone();
     String& a_s = String::Handle(zone);
     String& b_s = String::Handle(zone);
     a_s = a.IsFunction() ? Function::Cast(a).name() : String::Cast(a).raw();
     b_s = b.IsFunction() ? Function::Cast(b).name() : String::Cast(b).raw();
     ASSERT(a_s.IsSymbol() && b_s.IsSymbol());
     return a_s.raw() == b_s.raw();
   }
   static uword Hash(const Object& obj) {
     if (obj.IsFunction()) {
       return String::Handle(Function::Cast(obj).name()).Hash();
     } else {
       ASSERT(String::Cast(obj).IsSymbol());
       return String::Cast(obj).Hash();
     }
   }
   static RawObject* NewKey(const Function& function) {
     return function.raw();
   }
 };
 
 typedef UnorderedHashSet<FunctionsTraits> UniqueFunctionsSet;
 
 
 }  // namespace dart
 
 #endif  // VM_PRECOMPILER_H_