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>

[siva, 2012/07/19 19:38:23]

The compiler uses our BitVector class for all these kinds of bitmap needs.
This comes back to the generic question do we use our home brewed data
structures or the stl ones.

[cshapiro, 2012/07/19 22:34:29]

With regard to our off-line discussion, this is a distinct type whose behavior
is sufficiently different from BitVector to justify its existence.

+
 #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_