Do not install fillers when right trimming large objects.

src/heap/heap.cc

 // 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.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/once.h"
 #include "src/base/utils/random-number-generator.h"
@@ skipping 3303 matching lines @@
 template
 void Heap::RightTrimFixedArray<Heap::FROM_MUTATOR>(FixedArrayBase*, int);
 
 
 template<Heap::InvocationMode mode>
 void Heap::RightTrimFixedArray(FixedArrayBase* object, int elements_to_trim) {
   const int element_size = object->IsFixedArray() ? kPointerSize : kDoubleSize;
   const int bytes_to_trim = elements_to_trim * element_size;
 
   // For now this trick is only applied to objects in new and paged space.
-  DCHECK(!lo_space()->Contains(object));
   DCHECK(object->map() != fixed_cow_array_map());
 
   const int len = object->length();
   DCHECK(elements_to_trim < len);
 
   // Calculate location of new array end.
   Address new_end = object->address() + object->Size() - bytes_to_trim;
 
   // Technically in new space this write might be omitted (except for
   // debug mode which iterates through the heap), but to play safer
   // we still do it.
-  CreateFillerObjectAt(new_end, bytes_to_trim);
+  // We do not create a filler for objects in large object space.
+  // TODO(hpayer): We should shrink the large object page if the size
+  // of the object changed significantly.
+  if (!lo_space()->Contains(object)) {
+    CreateFillerObjectAt(new_end, bytes_to_trim);
+  }
 
   // Initialize header of the trimmed array. We are storing the new length
   // using release store after creating a filler for the left-over space to
   // avoid races with the sweeper thread.
   object->synchronized_set_length(len - elements_to_trim);
 
   // Maintain consistency of live bytes during incremental marking
   AdjustLiveBytes(object->address(), -bytes_to_trim, mode);
 
   // Notify the heap profiler of change in object layout. The array may not be
@@ skipping 2796 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
 
   MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 }
 }  // namespace v8::internal