Support slots recording for compaction during incremental marking.

src/heap.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 4286 matching lines @@
                                              Address end,
                                              ObjectSlotCallback callback) {
   Address slot_address = start;
   while (slot_address < end) {
     Object** slot = reinterpret_cast<Object**>(slot_address);
     Object* object = *slot;
     // If the store buffer becomes overfull we mark pages as being exempt from
     // the store buffer.  These pages are scanned to find pointers that point
     // to the new space.  In that case we may hit newly promoted objects and
     // fix the pointers before the promotion queue gets to them.  Thus the 'if'.
-    if (Heap::InFromSpace(object)) {
-      callback(reinterpret_cast<HeapObject**>(slot), HeapObject::cast(object));
-      if (InNewSpace(*slot)) {
-        ASSERT(Heap::InToSpace(*slot));
-        ASSERT((*slot)->IsHeapObject());
-        store_buffer_.EnterDirectlyIntoStoreBuffer(
-            reinterpret_cast<Address>(slot));
+    if (object->IsHeapObject()) {
+      if (Heap::InFromSpace(object)) {
+        callback(reinterpret_cast<HeapObject**>(slot),
+                 HeapObject::cast(object));
+        Object* new_object = *slot;
+        if (InNewSpace(new_object)) {
+          ASSERT(Heap::InToSpace(new_object));
+          ASSERT(new_object->IsHeapObject());
+          store_buffer_.EnterDirectlyIntoStoreBuffer(
+              reinterpret_cast<Address>(slot));
+        }
+        ASSERT(!MarkCompactCollector::IsOnEvacuationCandidate(new_object));
+      } else if (MarkCompactCollector::IsOnEvacuationCandidate(object)) {
+        // We are not collecting slots on new space objects during mutation
+        // thus we have to scan for pointers to evacuation candidates when we
+        // promote objects.
+        mark_compact_collector()->RecordSlot(slot, slot, object);
       }
     }
     slot_address += kPointerSize;
   }
 }
 
 
 #ifdef DEBUG
 typedef bool (*CheckStoreBufferFilter)(Object** addr);
 
@@ skipping 1523 matching lines @@
   }
   isolate_->heap()->store_buffer()->Filter(MemoryChunk::ABOUT_TO_BE_FREED);
   for (chunk = chunks_queued_for_free_; chunk != NULL; chunk = next) {
     next = chunk->next_chunk();
     isolate_->memory_allocator()->Free(chunk);
   }
   chunks_queued_for_free_ = NULL;
 }
 
 } }  // namespace v8::internal