After performing scavenge, hint OS that data in from spaces are no more neede...

src/spaces-inl.h

 // Copyright 2006-2008 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 156 matching lines @@
 bool Page::IsRSetSet(Address address, int offset) {
   uint32_t bitmask = 0;
   Address rset_address = ComputeRSetBitPosition(address, offset, &bitmask);
   return (Memory::uint32_at(rset_address) & bitmask) != 0;
 }
 
 
 // -----------------------------------------------------------------------------
 // MemoryAllocator
 
+bool MemoryAllocator::ResetBlock(Address start, size_t size,
+                                 Executability executable) {
+  return initial_chunk_->Reset(start, size, executable == EXECUTABLE);
+}
+
 bool MemoryAllocator::IsValidChunk(int chunk_id) {
   if (!IsValidChunkId(chunk_id)) return false;
 
   ChunkInfo& c = chunks_[chunk_id];
   return (c.address() != NULL) && (c.size() != 0) && (c.owner() != NULL);
 }
 
 
 bool MemoryAllocator::IsValidChunkId(int chunk_id) {
   return (0 <= chunk_id) && (chunk_id < max_nof_chunks_);
@@ skipping 128 matching lines @@
   if (object != NULL) return object;
 
   object = SlowMCAllocateRaw(size_in_bytes);
   if (object != NULL) return object;
 
   return Failure::RetryAfterGC(size_in_bytes, identity());
 }
 
 
 // -----------------------------------------------------------------------------
+// SemiSpace
+
+bool SemiSpace::Reset() {
+  return MemoryAllocator::ResetBlock(start_, capacity_, executable());
+}
+
+// -----------------------------------------------------------------------------
 // LargeObjectChunk
 
 HeapObject* LargeObjectChunk::GetObject() {
   // Round the chunk address up to the nearest page-aligned address
   // and return the heap object in that page.
   Page* page = Page::FromAddress(RoundUp(address(), Page::kPageSize));
   return HeapObject::FromAddress(page->ObjectAreaStart());
 }
 
 
@@ skipping 28 matching lines @@
 
 bool FreeListNode::IsFreeListNode(HeapObject* object) {
   return object->map() == Heap::raw_unchecked_byte_array_map()
       || object->map() == Heap::raw_unchecked_one_pointer_filler_map()
       || object->map() == Heap::raw_unchecked_two_pointer_filler_map();
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_SPACES_INL_H_