Short-circuit embedded cons strings.

src/objects-visiting-inl.h

Index: src/objects-visiting-inl.h
diff --git a/src/objects-visiting-inl.h b/src/objects-visiting-inl.h
index 6c3c9d44fe318d77c141a68dc6d562d86563aceb..b56e6ec2f0308b2c6859d831e8f90b26a23463ea 100644
--- a/src/objects-visiting-inl.h
+++ b/src/objects-visiting-inl.h
@@ -233,13 +233,16 @@ template<typename StaticVisitor>
 void StaticMarkingVisitor<StaticVisitor>::VisitEmbeddedPointer(
     Heap* heap, RelocInfo* rinfo) {
   ASSERT(rinfo->rmode() == RelocInfo::EMBEDDED_OBJECT);
-  ASSERT(!rinfo->target_object()->IsConsString());
   HeapObject* object = HeapObject::cast(rinfo->target_object());
   if (!FLAG_weak_embedded_maps_in_optimized_code || !FLAG_collect_maps ||
       rinfo->host()->kind() != Code::OPTIMIZED_FUNCTION ||
       !object->IsMap() || !Map::cast(object)->CanTransition()) {
-    heap->mark_compact_collector()->RecordRelocSlot(rinfo, object);
-    StaticVisitor::MarkObject(heap, object);
+    Object** target_address = rinfo->target_object_address();

[Michael Starzinger, 2013/06/20 23:25:27]

This change is missing the slot recording for the reloc slot in the code.
Frankly it surprises me that this would pass the test suite.

Also I am not sure passing a non-heap slot to the StaticVisitor here will work,
because if the target happens to be in an evacuation candidate this stack(!)
slot will be recorded in the slots buffer.

+    Object* old_target = *target_address;
+    StaticVisitor::VisitPointer(heap, target_address);
+    if (*target_address != old_target) {
+      rinfo->set_target_object(*target_address);
+    }
   }
 }