Access old space marking bits from runtime only when incremental marking is in MARKING state.

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index 27efaeaa1c0e761f10d7cf7b503426cbdbaa0894..38e090e9bcfdbf3396f0e6220ce8d8748d29622a 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -268,10 +268,8 @@ static FixedArrayBase* LeftTrimFixedArray(Heap* heap,
   // Maintain marking consistency for HeapObjectIterator and
   // IncrementalMarking.
   int size_delta = to_trim * entry_size;
-  if (heap->marking()->TransferMark(elms->address(),
-                                    elms->address() + size_delta)) {
-    MemoryChunk::IncrementLiveBytesFromMutator(elms->address(), -size_delta);
-  }
+  heap->marking()->TransferMark(elms->address(), elms->address() + size_delta);
+  heap->AdjustLiveBytes(elms->address(), -size_delta, Heap::FROM_MUTATOR);

[Michael Starzinger, 2014/03/19 11:25:26]

Unfortunately this is not correct. The adjustment happens after the mark bits
have been transferred but still targets the old address. Hence, the mark bit is
already gone.

Also I claim that AdjustLiveBytes() should not take an "Address" but and
"Object*" as a first parameter.

 
   FixedArrayBase* new_elms = FixedArrayBase::cast(HeapObject::FromAddress(
       elms->address() + size_delta));