Favor free list allocation to bump pointer allocation.

runtime/vm/freelist.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_FREELIST_H_
 #define VM_FREELIST_H_
 
+#include <bitset>
+
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/raw_object.h"
 
 namespace dart {
 
 // FreeListElement describes a freelist element.  Smallest FreeListElement is
 // two words in size.  Second word of the raw object is used to keep a next_
 // pointer to chain elements of the list together. For objects larger than the
 // object size encodable in tags field, the size of the element is embedded in
@@ skipping 53 matching lines @@
 class FreeList {
  public:
   FreeList();
   ~FreeList();
 
   uword TryAllocate(intptr_t size);
   void Free(uword addr, intptr_t size);
 
   void Reset();
 
+  intptr_t Length(int index) const;
+
+  void Print() const;
+
  private:
   static const int kNumLists = 128;
 
   static intptr_t IndexForSize(intptr_t size);
 
   void EnqueueElement(FreeListElement* element, intptr_t index);
   FreeListElement* DequeueElement(intptr_t index);
 
   void SplitElementAfterAndEnqueue(FreeListElement* element, intptr_t size);
 
+  std::bitset<kNumLists + 1> free_map_;
+
   FreeListElement* free_lists_[kNumLists + 1];
 
   DISALLOW_COPY_AND_ASSIGN(FreeList);
 };
 
 }  // namespace dart
 
 #endif  // VM_FREELIST_H_