Fix accumulated size stats for fixed-size instances.

runtime/vm/class_table.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_CLASS_TABLE_H_
 #define VM_CLASS_TABLE_H_
 
 #include "platform/assert.h"
 #include "vm/globals.h"
 
@@ skipping 34 matching lines @@
     old_count++;
     old_size += size;
   }
 
   void Reset() {
     new_count = 0;
     new_size = 0;
     old_count = 0;
     old_size = 0;
   }
+
+  // For classes with fixed instance size we do not emit code to update
+  // the size statistics. Update them by calling this method.
+  void UpdateSize(intptr_t instance_size) {
+    ASSERT(instance_size > 0);
+    old_size = old_count * instance_size;
+    new_size = new_count * instance_size;
+  }
 };
 
 class ClassHeapStats {
  public:
   // Snapshot before GC.
   AllocStats<intptr_t> pre_gc;
   // Live after GC.
   AllocStats<intptr_t> post_gc;
   // Allocations since the last GC.
   AllocStats<intptr_t> recent;
@@ skipping 108 matching lines @@
   ClassHeapStats* StatsAt(intptr_t cid);
   void UpdateLiveOld(intptr_t cid, intptr_t size);
   void UpdateLiveNew(intptr_t cid, intptr_t size);
 
   DISALLOW_COPY_AND_ASSIGN(ClassTable);
 };
 
 }  // namespace dart
 
 #endif  // VM_CLASS_TABLE_H_