diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index f7eb173..4a23f2a 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -92,6 +92,7 @@
 //       HCallNew
 //       HCallRuntime
 //     HCallStub
+//     HCheckPrototypeMaps
 //     HConstant
 //     HControlInstruction
 //       HDeoptimize
@@ -106,6 +107,7 @@
 //     HGlobalObject
 //     HGlobalReceiver
 //     HLeaveInlined
+//     HLoadContextSlot
 //     HLoadGlobal
 //     HMaterializedLiteral
 //       HArrayLiteral
@@ -125,7 +127,6 @@
 //       HCheckInstanceType
 //       HCheckMap
 //       HCheckNonSmi
-//       HCheckPrototypeMaps
 //       HCheckSmi
 //       HDeleteProperty
 //       HFixedArrayLength
@@ -220,6 +221,7 @@
   V(JSArrayLength)                             \
   V(ClassOfTest)                               \
   V(LeaveInlined)                              \
+  V(LoadContextSlot)                           \
   V(LoadElements)                              \
   V(LoadGlobal)                                \
   V(LoadKeyedFastElement)                      \
@@ -1622,42 +1624,40 @@
 };
 
 
-class HCheckPrototypeMaps: public HUnaryOperation {
+class HCheckPrototypeMaps: public HInstruction {
  public:
-  HCheckPrototypeMaps(HValue* value,
-                      Handle<JSObject> holder,
-                      Handle<Map> receiver_map)
-      : HUnaryOperation(value),
-        holder_(holder),
-        receiver_map_(receiver_map) {
-    set_representation(Representation::Tagged());
+  HCheckPrototypeMaps(Handle<JSObject> prototype, Handle<JSObject> holder)
+      : prototype_(prototype), holder_(holder) {
     SetFlag(kUseGVN);
     SetFlag(kDependsOnMaps);
   }
 
-  virtual Representation RequiredInputRepresentation(int index) const {
-    return Representation::Tagged();
-  }
-
 #ifdef DEBUG
   virtual void Verify() const;
 #endif
 
+  Handle<JSObject> prototype() const { return prototype_; }
   Handle<JSObject> holder() const { return holder_; }
-  Handle<Map> receiver_map() const { return receiver_map_; }
 
   DECLARE_CONCRETE_INSTRUCTION(CheckPrototypeMaps, "check_prototype_maps")
 
+  virtual intptr_t Hashcode() const {
+    ASSERT(!Heap::IsAllocationAllowed());
+    intptr_t hash = reinterpret_cast<intptr_t>(*prototype());
+    hash = 17 * hash + reinterpret_cast<intptr_t>(*holder());
+    return hash;
+  }
+
  protected:
   virtual bool DataEquals(HValue* other) const {
     HCheckPrototypeMaps* b = HCheckPrototypeMaps::cast(other);
-    return holder_.is_identical_to(b->holder()) &&
-        receiver_map_.is_identical_to(b->receiver_map());
+    return prototype_.is_identical_to(b->prototype()) &&
+        holder_.is_identical_to(b->holder());
   }
 
  private:
+  Handle<JSObject> prototype_;
   Handle<JSObject> holder_;
-  Handle<Map> receiver_map_;
 };
 
 
@@ -2601,6 +2601,39 @@
 };
 
 
+class HLoadContextSlot: public HInstruction {
+ public:
+  HLoadContextSlot(int context_chain_length , int slot_index)
+      : context_chain_length_(context_chain_length), slot_index_(slot_index) {
+    set_representation(Representation::Tagged());
+    SetFlag(kUseGVN);
+    SetFlag(kDependsOnCalls);
+  }
+
+  int context_chain_length() const { return context_chain_length_; }
+  int slot_index() const { return slot_index_; }
+
+  virtual void PrintDataTo(StringStream* stream) const;
+
+  virtual intptr_t Hashcode() const {
+    return context_chain_length() * 29 + slot_index();
+  }
+
+  DECLARE_CONCRETE_INSTRUCTION(LoadContextSlot, "load_context_slot")
+
+ protected:
+  virtual bool DataEquals(HValue* other) const {
+    HLoadContextSlot* b = HLoadContextSlot::cast(other);
+    return (context_chain_length() == b->context_chain_length())
+        && (slot_index() == b->slot_index());
+  }
+
+ private:
+  int context_chain_length_;
+  int slot_index_;
+};
+
+
 class HLoadNamedField: public HUnaryOperation {
  public:
   HLoadNamedField(HValue* object, bool is_in_object, int offset)