While allocating code objects, perform the incremental marking step before NULLing the new object. …

src/spaces.cc

 // Copyright 2011 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 2009 matching lines @@
 
   int bytes_left = new_node_size - size_in_bytes;
   ASSERT(bytes_left >= 0);
 
   int old_linear_size = static_cast<int>(owner_->limit() - owner_->top());
   // Mark the old linear allocation area with a free space map so it can be
   // skipped when scanning the heap.  This also puts it back in the free list
   // if it is big enough.
   owner_->Free(owner_->top(), old_linear_size);
 
-#ifdef DEBUG
-  for (int i = 0; i < size_in_bytes / kPointerSize; i++) {
-    reinterpret_cast<Object**>(new_node->address())[i] = Smi::FromInt(0);
-  }
-#endif
-
   owner_->heap()->incremental_marking()->OldSpaceStep(
       size_in_bytes - old_linear_size);
 
+#ifdef DEBUG
+  for (int i = 0; i < size_in_bytes / kPointerSize; i++) {
+    reinterpret_cast<Object**>(new_node->address())[i] =
+        Smi::FromInt(kCodeZapValue);
+  }
+#endif
+
   // The old-space-step might have finished sweeping and restarted marking.
   // Verify that it did not turn the page of the new node into an evacuation
   // candidate.
   ASSERT(!MarkCompactCollector::IsOnEvacuationCandidate(new_node));
 
   const int kThreshold = IncrementalMarking::kAllocatedThreshold;
 
   // Memory in the linear allocation area is counted as allocated.  We may free
   // a little of this again immediately - see below.
   owner_->Allocate(new_node_size);
@@ skipping 808 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal