diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 33bfe19..7549ebf 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -79,12 +79,14 @@
 };
 
 // Control-flow graph of a method. Contains a list of basic blocks.
-class HGraph : public ArenaObject {
+class HGraph : public ArenaObject<kArenaAllocMisc> {
  public:
   explicit HGraph(ArenaAllocator* arena)
       : arena_(arena),
         blocks_(arena, kDefaultNumberOfBlocks),
         reverse_post_order_(arena, kDefaultNumberOfBlocks),
+        entry_block_(nullptr),
+        exit_block_(nullptr),
         maximum_number_of_out_vregs_(0),
         number_of_vregs_(0),
         number_of_in_vregs_(0),
@@ -199,7 +201,7 @@
   DISALLOW_COPY_AND_ASSIGN(HGraph);
 };
 
-class HLoopInformation : public ArenaObject {
+class HLoopInformation : public ArenaObject<kArenaAllocMisc> {
  public:
   HLoopInformation(HBasicBlock* header, HGraph* graph)
       : header_(header),
@@ -278,7 +280,7 @@
 // as a double linked list. Each block knows its predecessors and
 // successors.
 
-class HBasicBlock : public ArenaObject {
+class HBasicBlock : public ArenaObject<kArenaAllocMisc> {
  public:
   explicit HBasicBlock(HGraph* graph, uint32_t dex_pc = kNoDexPc)
       : graph_(graph),
@@ -537,7 +539,7 @@
   virtual void Accept(HGraphVisitor* visitor)
 
 template <typename T>
-class HUseListNode : public ArenaObject {
+class HUseListNode : public ArenaObject<kArenaAllocMisc> {
  public:
   HUseListNode(T* user, size_t index, HUseListNode* tail)
       : user_(user), index_(index), tail_(tail) {}
@@ -619,7 +621,7 @@
   size_t flags_;
 };
 
-class HInstruction : public ArenaObject {
+class HInstruction : public ArenaObject<kArenaAllocMisc> {
  public:
   explicit HInstruction(SideEffects side_effects)
       : previous_(nullptr),
@@ -738,12 +740,18 @@
   virtual bool CanBeMoved() const { return false; }
 
   // Returns whether the two instructions are of the same kind.
-  virtual bool InstructionTypeEquals(HInstruction* other) const { return false; }
+  virtual bool InstructionTypeEquals(HInstruction* other) const {
+    UNUSED(other);
+    return false;
+  }
 
   // Returns whether any data encoded in the two instructions is equal.
   // This method does not look at the inputs. Both instructions must be
   // of the same type, otherwise the method has undefined behavior.
-  virtual bool InstructionDataEquals(HInstruction* other) const { return false; }
+  virtual bool InstructionDataEquals(HInstruction* other) const {
+    UNUSED(other);
+    return false;
+  }
 
   // Returns whether two instructions are equal, that is:
   // 1) They have the same type and contain the same data,
@@ -808,6 +816,7 @@
 
   DISALLOW_COPY_AND_ASSIGN(HInstruction);
 };
+std::ostream& operator<<(std::ostream& os, const HInstruction::InstructionKind& rhs);
 
 template<typename T>
 class HUseIterator : public ValueObject {
@@ -833,7 +842,7 @@
 };
 
 // A HEnvironment object contains the values of virtual registers at a given location.
-class HEnvironment : public ArenaObject {
+class HEnvironment : public ArenaObject<kArenaAllocMisc> {
  public:
   HEnvironment(ArenaAllocator* arena, size_t number_of_vregs) : vregs_(arena, number_of_vregs) {
     vregs_.SetSize(number_of_vregs);
@@ -965,14 +974,14 @@
  public:
   intptr_t length() const { return 0; }
   const T& operator[](intptr_t i) const {
+    UNUSED(i);
     LOG(FATAL) << "Unreachable";
-    static T sentinel = 0;
-    return sentinel;
+    UNREACHABLE();
   }
   T& operator[](intptr_t i) {
+    UNUSED(i);
     LOG(FATAL) << "Unreachable";
-    static T sentinel = 0;
-    return sentinel;
+    UNREACHABLE();
   }
 };
 
@@ -1110,7 +1119,10 @@
   Primitive::Type GetResultType() const { return GetType(); }
 
   virtual bool CanBeMoved() const { return true; }
-  virtual bool InstructionDataEquals(HInstruction* other) const { return true; }
+  virtual bool InstructionDataEquals(HInstruction* other) const {
+    UNUSED(other);
+    return true;
+  }
 
   // Try to statically evaluate `operation` and return a HConstant
   // containing the result of this evaluation.  If `operation` cannot
@@ -1143,7 +1155,10 @@
   virtual bool IsCommutative() { return false; }
 
   virtual bool CanBeMoved() const { return true; }
-  virtual bool InstructionDataEquals(HInstruction* other) const { return true; }
+  virtual bool InstructionDataEquals(HInstruction* other) const {
+    UNUSED(other);
+    return true;
+  }
 
   // Try to statically evaluate `operation` and return a HConstant
   // containing the result of this evaluation.  If `operation` cannot
@@ -1732,7 +1747,10 @@
       : HUnaryOperation(result_type, input) {}
 
   virtual bool CanBeMoved() const { return true; }
-  virtual bool InstructionDataEquals(HInstruction* other) const { return true; }
+  virtual bool InstructionDataEquals(HInstruction* other) const {
+    UNUSED(other);
+    return true;
+  }
 
   virtual int32_t Evaluate(int32_t x) const OVERRIDE { return ~x; }
   virtual int64_t Evaluate(int64_t x) const OVERRIDE { return ~x; }
@@ -1792,7 +1810,10 @@
   }
 
   virtual bool CanBeMoved() const { return true; }
-  virtual bool InstructionDataEquals(HInstruction* other) const { return true; }
+  virtual bool InstructionDataEquals(HInstruction* other) const {
+    UNUSED(other);
+    return true;
+  }
 
   virtual bool NeedsEnvironment() const { return true; }
 
@@ -1884,7 +1905,10 @@
   }
 
   virtual bool CanBeMoved() const { return true; }
-  virtual bool InstructionDataEquals(HInstruction* other) const { return true; }
+  virtual bool InstructionDataEquals(HInstruction* other) const {
+    UNUSED(other);
+    return true;
+  }
   void SetType(Primitive::Type type) { type_ = type; }
 
   DECLARE_INSTRUCTION(ArrayGet);
@@ -1948,7 +1972,10 @@
   }
 
   virtual bool CanBeMoved() const { return true; }
-  virtual bool InstructionDataEquals(HInstruction* other) const { return true; }
+  virtual bool InstructionDataEquals(HInstruction* other) const {
+    UNUSED(other);
+    return true;
+  }
 
   DECLARE_INSTRUCTION(ArrayLength);
 
@@ -1966,7 +1993,10 @@
   }
 
   virtual bool CanBeMoved() const { return true; }
-  virtual bool InstructionDataEquals(HInstruction* other) const { return true; }
+  virtual bool InstructionDataEquals(HInstruction* other) const {
+    UNUSED(other);
+    return true;
+  }
 
   virtual bool NeedsEnvironment() const { return true; }
 
@@ -2177,7 +2207,7 @@
   DISALLOW_COPY_AND_ASSIGN(HStaticFieldSet);
 };
 
-class MoveOperands : public ArenaObject {
+class MoveOperands : public ArenaObject<kArenaAllocMisc> {
  public:
   MoveOperands(Location source, Location destination, HInstruction* instruction)
       : source_(source), destination_(destination), instruction_(instruction) {}
@@ -2278,7 +2308,7 @@
   explicit HGraphVisitor(HGraph* graph) : graph_(graph) {}
   virtual ~HGraphVisitor() {}
 
-  virtual void VisitInstruction(HInstruction* instruction) {}
+  virtual void VisitInstruction(HInstruction* instruction) { UNUSED(instruction); }
   virtual void VisitBasicBlock(HBasicBlock* block);
 
   // Visit the graph following basic block insertion order.