Speedup function profile by using a hash table instead of a linear scan

runtime/vm/object.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_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 2231 matching lines @@
   bool HasCode() const;
 
   static intptr_t code_offset() {
     return OFFSET_OF(RawFunction, code_);
   }
 
   static intptr_t entry_point_offset() {
     return OFFSET_OF(RawFunction, entry_point_);
   }
 
+  virtual intptr_t Hash() const;
+
   // Returns true if there is at least one debugger breakpoint
   // set in this function.
   bool HasBreakpoint() const;
 
   RawContextScope* context_scope() const;
   void set_context_scope(const ContextScope& value) const;
 
   RawField* LookupImplicitGetterSetterField() const;
 
   // Enclosing function of this local function.
@@ skipping 6153 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_