[heap] Tweak evacuation candidate selection.

src/heap/mark-compact.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_MARK_COMPACT_H_
 #define V8_HEAP_MARK_COMPACT_H_
 
 #include "src/base/bits.h"
 #include "src/heap/spaces.h"
 
@@ skipping 506 matching lines @@
 
   explicit MarkCompactCollector(Heap* heap);
   ~MarkCompactCollector();
 
   bool WillBeDeoptimized(Code* code);
   void EvictPopularEvacuationCandidate(Page* page);
   void ClearInvalidStoreAndSlotsBufferEntries();
 
   void StartSweeperThreads();
 
+  void ComputeEvacuationHeuristics(int area_size,
+                                   int* target_fragmentation_percent,
+                                   int* max_evacuated_bytes);
+
 #ifdef DEBUG
   enum CollectorState {
     IDLE,
     PREPARE_GC,
     MARK_LIVE_OBJECTS,
     SWEEP_SPACES,
     ENCODE_FORWARDING_ADDRESSES,
     UPDATE_POINTERS,
     RELOCATE_OBJECTS
   };
@@ skipping 324 matching lines @@
  private:
   MarkCompactCollector* collector_;
 };
 
 
 const char* AllocationSpaceName(AllocationSpace space);
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_MARK_COMPACT_H_