Add filler at the new space top when forcing scavenge.

src/heap.cc

 // Copyright 2012 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 755 matching lines @@
       break;
     }
   }
   mark_compact_collector()->SetFlags(kNoGCFlags);
   new_space_.Shrink();
   UncommitFromSpace();
   incremental_marking()->UncommitMarkingDeque();
 }
 
 
+void Heap::EnsureFillerObjectAtTop() {
+  // There may be an allocation memento behind every object in new space.
+  // If we evacuate a not full new space or if we are on the last page of
+  // the new space, then there may be uninitialized memory behind the top
+  // pointer of the new space page. We store a filler object there to
+  // identify the unused space.
+  Address from_top = new_space_.top();
+  Address from_limit = new_space_.limit();
+  if (from_top < from_limit) {
+    int remaining_in_page = static_cast<int>(from_limit - from_top);
+    CreateFillerObjectAt(from_top, remaining_in_page);
+  }
+}
+
+
 bool Heap::CollectGarbage(GarbageCollector collector,
                           const char* gc_reason,
                           const char* collector_reason,
                           const v8::GCCallbackFlags gc_callback_flags) {
   // The VM is in the GC state until exiting this function.
   VMState<GC> state(isolate_);
 
 #ifdef DEBUG
   // Reset the allocation timeout to the GC interval, but make sure to
   // allow at least a few allocations after a collection. The reason
   // for this is that we have a lot of allocation sequences and we
   // assume that a garbage collection will allow the subsequent
   // allocation attempts to go through.
   allocation_timeout_ = Max(6, FLAG_gc_interval);
 #endif
 
-  // There may be an allocation memento behind every object in new space.
-  // If we evacuate a not full new space or if we are on the last page of
-  // the new space, then there may be uninitialized memory behind the top
-  // pointer of the new space page. We store a filler object there to
-  // identify the unused space.
-  Address from_top = new_space_.top();
-  Address from_limit = new_space_.limit();
-  if (from_top < from_limit) {
-    int remaining_in_page = static_cast<int>(from_limit - from_top);
-    CreateFillerObjectAt(from_top, remaining_in_page);
-  }
+  EnsureFillerObjectAtTop();
 
   if (collector == SCAVENGER && !incremental_marking()->IsStopped()) {
     if (FLAG_trace_incremental_marking) {
       PrintF("[IncrementalMarking] Scavenge during marking.\n");
     }
   }
 
   if (collector == MARK_COMPACTOR &&
       !mark_compact_collector()->abort_incremental_marking() &&
       !incremental_marking()->IsStopped() &&
@@ skipping 53 matching lines @@
   if (isolate()->concurrent_recompilation_enabled()) {
     // Flush the queued recompilation tasks.
     isolate()->optimizing_compiler_thread()->Flush();
   }
   flush_monomorphic_ics_ = true;
   AgeInlineCaches();
   return ++contexts_disposed_;
 }
 
 
-void Heap::PerformScavenge() {
-  GCTracer tracer(this, NULL, NULL);
-  if (incremental_marking()->IsStopped()) {
-    PerformGarbageCollection(SCAVENGER, &tracer);
-  } else {
-    PerformGarbageCollection(MARK_COMPACTOR, &tracer);
-  }
-}
-
-
 void Heap::MoveElements(FixedArray* array,
                         int dst_index,
                         int src_index,
                         int len) {
   if (len == 0) return;
 
   ASSERT(array->map() != fixed_cow_array_map());
   Object** dst_objects = array->data_start() + dst_index;
   OS::MemMove(dst_objects,
               array->data_start() + src_index,
@@ skipping 6852 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   OS::MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   OS::MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal