GC. Delay/avoid entering high promotion mode

src/heap/heap.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_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 1354 matching lines @@
 
   // This should be used only for testing.
   void set_old_generation_allocation_counter(size_t new_value) {
     old_generation_allocation_counter_ = new_value;
   }
 
   size_t PromotedSinceLastGC() {
     return PromotedSpaceSizeOfObjects() - old_generation_size_at_last_gc_;
   }
 
+  // Record the fact that we generated some optimized code since the last GC
+  // which will pretenure some previously unpretenured allocation.
+  void RecordDeoptForPretenuring() { gathering_lifetime_feedback_ = 2; }
+
   // Update GC statistics that are tracked on the Heap.
   void UpdateCumulativeGCStatistics(double duration, double spent_in_mutator,
                                     double marking_time);
 
   // Returns maximum GC pause.
   double get_max_gc_pause() { return max_gc_pause_; }
 
   // Returns maximum size of objects alive after GC.
   intptr_t get_max_alive_after_gc() { return max_alive_after_gc_; }
 
@@ skipping 781 matching lines @@
 
   enum SurvivalRateTrend { INCREASING, STABLE, DECREASING, FLUCTUATING };
 
   static const int kYoungSurvivalRateHighThreshold = 90;
   static const int kYoungSurvivalRateLowThreshold = 10;
   static const int kYoungSurvivalRateAllowedDeviation = 15;
 
   static const int kOldSurvivalRateLowThreshold = 10;
 
   bool new_space_high_promotion_mode_active_;
+  // If this is non-zero, then there is hope yet that the optimized code we
+  // have generated will solve our high promotion rate problems, so we don't
+  // need to go into high promotion mode just yet.
+  int gathering_lifetime_feedback_;
   int high_survival_rate_period_length_;
   intptr_t promoted_objects_size_;
   int low_survival_rate_period_length_;
   double survival_rate_;
   double promotion_ratio_;
   double promotion_rate_;
   intptr_t semi_space_copied_object_size_;
   intptr_t previous_semi_space_copied_object_size_;
   double semi_space_copied_rate_;
   int nodes_died_in_new_space_;
@@ skipping 46 matching lines @@
         return false;
     }
   }
 
   bool IsIncreasingSurvivalTrend() {
     return survival_rate_trend() == INCREASING;
   }
 
   bool IsLowSurvivalRate() { return low_survival_rate_period_length_ > 0; }
 
-  // TODO(hpayer): Allocation site pretenuring may make this method obsolete.
-  // Re-visit incremental marking heuristics.
   bool IsHighSurvivalRate() { return high_survival_rate_period_length_ > 0; }
 
   void ConfigureInitialOldGenerationSize();
 
   void ConfigureNewGenerationSize();
 
   void SelectScavengingVisitorsTable();
 
   bool HasLowYoungGenerationAllocationRate();
   bool HasLowOldGenerationAllocationRate();
@@ skipping 598 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_H_