diff --git a/src/heap/objects-visiting.cc b/src/heap/objects-visiting.cc
new file mode 100644
index 0000000..a0fc231
--- /dev/null
+++ b/src/heap/objects-visiting.cc
@@ -0,0 +1,413 @@
+// Copyright 2011 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/v8.h"
+
+#include "src/heap/objects-visiting.h"
+
+namespace v8 {
+namespace internal {
+
+
+StaticVisitorBase::VisitorId StaticVisitorBase::GetVisitorId(
+    int instance_type, int instance_size) {
+  if (instance_type < FIRST_NONSTRING_TYPE) {
+    switch (instance_type & kStringRepresentationMask) {
+      case kSeqStringTag:
+        if ((instance_type & kStringEncodingMask) == kOneByteStringTag) {
+          return kVisitSeqOneByteString;
+        } else {
+          return kVisitSeqTwoByteString;
+        }
+
+      case kConsStringTag:
+        if (IsShortcutCandidate(instance_type)) {
+          return kVisitShortcutCandidate;
+        } else {
+          return kVisitConsString;
+        }
+
+      case kSlicedStringTag:
+        return kVisitSlicedString;
+
+      case kExternalStringTag:
+        return GetVisitorIdForSize(kVisitDataObject, kVisitDataObjectGeneric,
+                                   instance_size);
+    }
+    UNREACHABLE();
+  }
+
+  switch (instance_type) {
+    case BYTE_ARRAY_TYPE:
+      return kVisitByteArray;
+
+    case FREE_SPACE_TYPE:
+      return kVisitFreeSpace;
+
+    case FIXED_ARRAY_TYPE:
+      return kVisitFixedArray;
+
+    case FIXED_DOUBLE_ARRAY_TYPE:
+      return kVisitFixedDoubleArray;
+
+    case CONSTANT_POOL_ARRAY_TYPE:
+      return kVisitConstantPoolArray;
+
+    case ODDBALL_TYPE:
+      return kVisitOddball;
+
+    case MAP_TYPE:
+      return kVisitMap;
+
+    case CODE_TYPE:
+      return kVisitCode;
+
+    case CELL_TYPE:
+      return kVisitCell;
+
+    case PROPERTY_CELL_TYPE:
+      return kVisitPropertyCell;
+
+    case JS_SET_TYPE:
+      return GetVisitorIdForSize(kVisitStruct, kVisitStructGeneric,
+                                 JSSet::kSize);
+
+    case JS_MAP_TYPE:
+      return GetVisitorIdForSize(kVisitStruct, kVisitStructGeneric,
+                                 JSMap::kSize);
+
+    case JS_WEAK_MAP_TYPE:
+    case JS_WEAK_SET_TYPE:
+      return kVisitJSWeakCollection;
+
+    case JS_REGEXP_TYPE:
+      return kVisitJSRegExp;
+
+    case SHARED_FUNCTION_INFO_TYPE:
+      return kVisitSharedFunctionInfo;
+
+    case JS_PROXY_TYPE:
+      return GetVisitorIdForSize(kVisitStruct, kVisitStructGeneric,
+                                 JSProxy::kSize);
+
+    case JS_FUNCTION_PROXY_TYPE:
+      return GetVisitorIdForSize(kVisitStruct, kVisitStructGeneric,
+                                 JSFunctionProxy::kSize);
+
+    case FOREIGN_TYPE:
+      return GetVisitorIdForSize(kVisitDataObject, kVisitDataObjectGeneric,
+                                 Foreign::kSize);
+
+    case SYMBOL_TYPE:
+      return kVisitSymbol;
+
+    case FILLER_TYPE:
+      return kVisitDataObjectGeneric;
+
+    case JS_ARRAY_BUFFER_TYPE:
+      return kVisitJSArrayBuffer;
+
+    case JS_TYPED_ARRAY_TYPE:
+      return kVisitJSTypedArray;
+
+    case JS_DATA_VIEW_TYPE:
+      return kVisitJSDataView;
+
+    case JS_OBJECT_TYPE:
+    case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
+    case JS_GENERATOR_OBJECT_TYPE:
+    case JS_MODULE_TYPE:
+    case JS_VALUE_TYPE:
+    case JS_DATE_TYPE:
+    case JS_ARRAY_TYPE:
+    case JS_GLOBAL_PROXY_TYPE:
+    case JS_GLOBAL_OBJECT_TYPE:
+    case JS_BUILTINS_OBJECT_TYPE:
+    case JS_MESSAGE_OBJECT_TYPE:
+    case JS_SET_ITERATOR_TYPE:
+    case JS_MAP_ITERATOR_TYPE:
+      return GetVisitorIdForSize(kVisitJSObject, kVisitJSObjectGeneric,
+                                 instance_size);
+
+    case JS_FUNCTION_TYPE:
+      return kVisitJSFunction;
+
+    case HEAP_NUMBER_TYPE:
+    case MUTABLE_HEAP_NUMBER_TYPE:
+#define EXTERNAL_ARRAY_CASE(Type, type, TYPE, ctype, size) \
+  case EXTERNAL_##TYPE##_ARRAY_TYPE:
+
+      TYPED_ARRAYS(EXTERNAL_ARRAY_CASE)
+      return GetVisitorIdForSize(kVisitDataObject, kVisitDataObjectGeneric,
+                                 instance_size);
+#undef EXTERNAL_ARRAY_CASE
+
+    case FIXED_UINT8_ARRAY_TYPE:
+    case FIXED_INT8_ARRAY_TYPE:
+    case FIXED_UINT16_ARRAY_TYPE:
+    case FIXED_INT16_ARRAY_TYPE:
+    case FIXED_UINT32_ARRAY_TYPE:
+    case FIXED_INT32_ARRAY_TYPE:
+    case FIXED_FLOAT32_ARRAY_TYPE:
+    case FIXED_UINT8_CLAMPED_ARRAY_TYPE:
+      return kVisitFixedTypedArray;
+
+    case FIXED_FLOAT64_ARRAY_TYPE:
+      return kVisitFixedFloat64Array;
+
+#define MAKE_STRUCT_CASE(NAME, Name, name) case NAME##_TYPE:
+      STRUCT_LIST(MAKE_STRUCT_CASE)
+#undef MAKE_STRUCT_CASE
+      if (instance_type == ALLOCATION_SITE_TYPE) {
+        return kVisitAllocationSite;
+      }
+
+      return GetVisitorIdForSize(kVisitStruct, kVisitStructGeneric,
+                                 instance_size);
+
+    default:
+      UNREACHABLE();
+      return kVisitorIdCount;
+  }
+}
+
+
+// We don't record weak slots during marking or scavenges. Instead we do it
+// once when we complete mark-compact cycle.  Note that write barrier has no
+// effect if we are already in the middle of compacting mark-sweep cycle and we
+// have to record slots manually.
+static bool MustRecordSlots(Heap* heap) {
+  return heap->gc_state() == Heap::MARK_COMPACT &&
+         heap->mark_compact_collector()->is_compacting();
+}
+
+
+template <class T>
+struct WeakListVisitor;
+
+
+template <class T>
+Object* VisitWeakList(Heap* heap, Object* list, WeakObjectRetainer* retainer) {
+  Object* undefined = heap->undefined_value();
+  Object* head = undefined;
+  T* tail = NULL;
+  MarkCompactCollector* collector = heap->mark_compact_collector();
+  bool record_slots = MustRecordSlots(heap);
+  while (list != undefined) {
+    // Check whether to keep the candidate in the list.
+    T* candidate = reinterpret_cast<T*>(list);
+    Object* retained = retainer->RetainAs(list);
+    if (retained != NULL) {
+      if (head == undefined) {
+        // First element in the list.
+        head = retained;
+      } else {
+        // Subsequent elements in the list.
+        DCHECK(tail != NULL);
+        WeakListVisitor<T>::SetWeakNext(tail, retained);
+        if (record_slots) {
+          Object** next_slot =
+              HeapObject::RawField(tail, WeakListVisitor<T>::WeakNextOffset());
+          collector->RecordSlot(next_slot, next_slot, retained);
+        }
+      }
+      // Retained object is new tail.
+      DCHECK(!retained->IsUndefined());
+      candidate = reinterpret_cast<T*>(retained);
+      tail = candidate;
+
+
+      // tail is a live object, visit it.
+      WeakListVisitor<T>::VisitLiveObject(heap, tail, retainer);
+    } else {
+      WeakListVisitor<T>::VisitPhantomObject(heap, candidate);
+    }
+
+    // Move to next element in the list.
+    list = WeakListVisitor<T>::WeakNext(candidate);
+  }
+
+  // Terminate the list if there is one or more elements.
+  if (tail != NULL) {
+    WeakListVisitor<T>::SetWeakNext(tail, undefined);
+  }
+  return head;
+}
+
+
+template <class T>
+static void ClearWeakList(Heap* heap, Object* list) {
+  Object* undefined = heap->undefined_value();
+  while (list != undefined) {
+    T* candidate = reinterpret_cast<T*>(list);
+    list = WeakListVisitor<T>::WeakNext(candidate);
+    WeakListVisitor<T>::SetWeakNext(candidate, undefined);
+  }
+}
+
+
+template <>
+struct WeakListVisitor<JSFunction> {
+  static void SetWeakNext(JSFunction* function, Object* next) {
+    function->set_next_function_link(next);
+  }
+
+  static Object* WeakNext(JSFunction* function) {
+    return function->next_function_link();
+  }
+
+  static int WeakNextOffset() { return JSFunction::kNextFunctionLinkOffset; }
+
+  static void VisitLiveObject(Heap*, JSFunction*, WeakObjectRetainer*) {}
+
+  static void VisitPhantomObject(Heap*, JSFunction*) {}
+};
+
+
+template <>
+struct WeakListVisitor<Code> {
+  static void SetWeakNext(Code* code, Object* next) {
+    code->set_next_code_link(next);
+  }
+
+  static Object* WeakNext(Code* code) { return code->next_code_link(); }
+
+  static int WeakNextOffset() { return Code::kNextCodeLinkOffset; }
+
+  static void VisitLiveObject(Heap*, Code*, WeakObjectRetainer*) {}
+
+  static void VisitPhantomObject(Heap*, Code*) {}
+};
+
+
+template <>
+struct WeakListVisitor<Context> {
+  static void SetWeakNext(Context* context, Object* next) {
+    context->set(Context::NEXT_CONTEXT_LINK, next, UPDATE_WRITE_BARRIER);
+  }
+
+  static Object* WeakNext(Context* context) {
+    return context->get(Context::NEXT_CONTEXT_LINK);
+  }
+
+  static int WeakNextOffset() {
+    return FixedArray::SizeFor(Context::NEXT_CONTEXT_LINK);
+  }
+
+  static void VisitLiveObject(Heap* heap, Context* context,
+                              WeakObjectRetainer* retainer) {
+    // Process the three weak lists linked off the context.
+    DoWeakList<JSFunction>(heap, context, retainer,
+                           Context::OPTIMIZED_FUNCTIONS_LIST);
+    DoWeakList<Code>(heap, context, retainer, Context::OPTIMIZED_CODE_LIST);
+    DoWeakList<Code>(heap, context, retainer, Context::DEOPTIMIZED_CODE_LIST);
+  }
+
+  template <class T>
+  static void DoWeakList(Heap* heap, Context* context,
+                         WeakObjectRetainer* retainer, int index) {
+    // Visit the weak list, removing dead intermediate elements.
+    Object* list_head = VisitWeakList<T>(heap, context->get(index), retainer);
+
+    // Update the list head.
+    context->set(index, list_head, UPDATE_WRITE_BARRIER);
+
+    if (MustRecordSlots(heap)) {
+      // Record the updated slot if necessary.
+      Object** head_slot =
+          HeapObject::RawField(context, FixedArray::SizeFor(index));
+      heap->mark_compact_collector()->RecordSlot(head_slot, head_slot,
+                                                 list_head);
+    }
+  }
+
+  static void VisitPhantomObject(Heap* heap, Context* context) {
+    ClearWeakList<JSFunction>(heap,
+                              context->get(Context::OPTIMIZED_FUNCTIONS_LIST));
+    ClearWeakList<Code>(heap, context->get(Context::OPTIMIZED_CODE_LIST));
+    ClearWeakList<Code>(heap, context->get(Context::DEOPTIMIZED_CODE_LIST));
+  }
+};
+
+
+template <>
+struct WeakListVisitor<JSArrayBufferView> {
+  static void SetWeakNext(JSArrayBufferView* obj, Object* next) {
+    obj->set_weak_next(next);
+  }
+
+  static Object* WeakNext(JSArrayBufferView* obj) { return obj->weak_next(); }
+
+  static int WeakNextOffset() { return JSArrayBufferView::kWeakNextOffset; }
+
+  static void VisitLiveObject(Heap*, JSArrayBufferView*, WeakObjectRetainer*) {}
+
+  static void VisitPhantomObject(Heap*, JSArrayBufferView*) {}
+};
+
+
+template <>
+struct WeakListVisitor<JSArrayBuffer> {
+  static void SetWeakNext(JSArrayBuffer* obj, Object* next) {
+    obj->set_weak_next(next);
+  }
+
+  static Object* WeakNext(JSArrayBuffer* obj) { return obj->weak_next(); }
+
+  static int WeakNextOffset() { return JSArrayBuffer::kWeakNextOffset; }
+
+  static void VisitLiveObject(Heap* heap, JSArrayBuffer* array_buffer,
+                              WeakObjectRetainer* retainer) {
+    Object* typed_array_obj = VisitWeakList<JSArrayBufferView>(
+        heap, array_buffer->weak_first_view(), retainer);
+    array_buffer->set_weak_first_view(typed_array_obj);
+    if (typed_array_obj != heap->undefined_value() && MustRecordSlots(heap)) {
+      Object** slot = HeapObject::RawField(array_buffer,
+                                           JSArrayBuffer::kWeakFirstViewOffset);
+      heap->mark_compact_collector()->RecordSlot(slot, slot, typed_array_obj);
+    }
+  }
+
+  static void VisitPhantomObject(Heap* heap, JSArrayBuffer* phantom) {
+    Runtime::FreeArrayBuffer(heap->isolate(), phantom);
+  }
+};
+
+
+template <>
+struct WeakListVisitor<AllocationSite> {
+  static void SetWeakNext(AllocationSite* obj, Object* next) {
+    obj->set_weak_next(next);
+  }
+
+  static Object* WeakNext(AllocationSite* obj) { return obj->weak_next(); }
+
+  static int WeakNextOffset() { return AllocationSite::kWeakNextOffset; }
+
+  static void VisitLiveObject(Heap*, AllocationSite*, WeakObjectRetainer*) {}
+
+  static void VisitPhantomObject(Heap*, AllocationSite*) {}
+};
+
+
+template Object* VisitWeakList<Code>(Heap* heap, Object* list,
+                                     WeakObjectRetainer* retainer);
+
+
+template Object* VisitWeakList<JSFunction>(Heap* heap, Object* list,
+                                           WeakObjectRetainer* retainer);
+
+
+template Object* VisitWeakList<Context>(Heap* heap, Object* list,
+                                        WeakObjectRetainer* retainer);
+
+
+template Object* VisitWeakList<JSArrayBuffer>(Heap* heap, Object* list,
+                                              WeakObjectRetainer* retainer);
+
+
+template Object* VisitWeakList<AllocationSite>(Heap* heap, Object* list,
+                                               WeakObjectRetainer* retainer);
+}
+}  // namespace v8::internal