Add unreachable instruction to Subzero.

src/IceOperand.h

 //===- subzero/src/IceOperand.h - High-level operands -----------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the Operand class and its target-independent
@@ skipping 66 matching lines @@
   const OperandKind Kind;
   // Vars and NumVars are initialized by the derived class.
   SizeT NumVars;
   Variable **Vars;
 
 private:
   Operand(const Operand &) LLVM_DELETED_FUNCTION;
   Operand &operator=(const Operand &) LLVM_DELETED_FUNCTION;
 };
 
+template<class StreamType>
+inline StreamType &operator<<(StreamType &Str, const Operand &Op) {
+  Op.dump(Str);
+  return Str;
+}
+
 // Constant is the abstract base class for constants.  All
 // constants are allocated from a global arena and are pooled.
 class Constant : public Operand {
 public:
   uint32_t getPoolEntryID() const { return PoolEntryID; }
   using Operand::dump;
   virtual void emit(const Cfg *Func) const { emit(Func->getContext()); }
   virtual void emit(GlobalContext *Ctx) const = 0;
   virtual void dump(const Cfg *Func, Ostream &Str) const = 0;
 
@@ skipping 387 matching lines @@
   Variable *LoVar;
   Variable *HiVar;
   // VarsReal (and Operand::Vars) are set up such that Vars[0] ==
   // this.
   Variable *VarsReal[1];
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEOPERAND_H