Minor adjustments to the object migration code: When copying...

src/heap.cc

 // 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 715 matching lines @@
   }
 }
 #endif  // defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
 
 
 HeapObject* Heap::MigrateObject(HeapObject** source_p,
                                 HeapObject* target,
                                 int size) {
   void** src = reinterpret_cast<void**>((*source_p)->address());
   void** dst = reinterpret_cast<void**>(target->address());
-  int counter = size/kPointerSize - 1;
-  do {
-    *dst++ = *src++;
-  } while (counter-- > 0);
+
+  // Use block copying memcpy if the object we're migrating is big
+  // enough to justify the extra call/setup overhead.
+  static const int kBlockCopyLimit = 16 * kPointerSize;
+
+  if (size >= kBlockCopyLimit) {
+    memcpy(dst, src, size);
+  } else {
+    int remaining = size / kPointerSize;
+    do {
+      remaining--;
+      *dst++ = *src++;
+    } while (remaining > 0);
+  }
 
   // Set the forwarding address.
   (*source_p)->set_map_word(MapWord::FromForwardingAddress(target));
 
   // Update NewSpace stats if necessary.
 #if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
   RecordCopiedObject(target);
 #endif
 
   return target;
@@ skipping 2309 matching lines @@
       return "Scavenge";
     case MARK_COMPACTOR:
       return MarkCompactCollector::HasCompacted() ? "Mark-compact"
                                                   : "Mark-sweep";
   }
   return "Unknown GC";
 }
 
 
 } }  // namespace v8::internal