Implement high promotion mode for new space.

src/heap.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1551 matching lines @@
   // remain until the next failure and garbage collection.
   int allocation_timeout_;
 
   // Do we expect to be able to handle allocation failure at this
   // time?
   bool disallow_allocation_failure_;
 
   HeapDebugUtils* debug_utils_;
 #endif  // DEBUG
 
+  // Indicates that the new space should be kept small due to high promotion
+  // rates caused by the mutator allocating a lot of long-lived objects.
+  bool new_space_high_promotion_mode_active_;
+
   // Limit that triggers a global GC on the next (normally caused) GC.  This
   // is checked when we have already decided to do a GC to help determine
   // which collector to invoke.
   intptr_t old_gen_promotion_limit_;
 
   // Limit that triggers a global GC as soon as is reasonable.  This is
   // checked before expanding a paged space in the old generation and on
   // every allocation in large object space.
   intptr_t old_gen_allocation_limit_;
 
@@ skipping 220 matching lines @@
         return true;
       default:
         return false;
     }
   }
 
   bool IsIncreasingSurvivalTrend() {
     return survival_rate_trend() == INCREASING;
   }
 
+  bool IsDecreasingSurvivalTrend() {
+    return survival_rate_trend() == DECREASING;
+  }
+
   bool IsHighSurvivalRate() {
     return high_survival_rate_period_length_ > 0;
   }
 
   void SelectScavengingVisitorsTable();
 
   static const int kInitialSymbolTableSize = 2048;
   static const int kInitialEvalCacheSize = 64;
 
   // Maximum GC pause.
@@ skipping 719 matching lines @@
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG || LIVE_OBJECT_LIST
 
 } }  // namespace v8::internal
 
 #undef HEAP
 
 #endif  // V8_HEAP_H_