Subzero: Fix some issues related to legalization and undef handling.

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 199 matching lines @@
 // legal to lower ConstantUndef to any value, backends should try to
 // make code generation deterministic by lowering ConstantUndefs to 0.
 class ConstantUndef : public Constant {
 public:
   static ConstantUndef *create(GlobalContext *Ctx, Type Ty,
                                uint32_t PoolEntryID) {
     return new (Ctx->allocate<ConstantUndef>()) ConstantUndef(Ty, PoolEntryID);
   }
 
   using Constant::emit;
-  virtual void emit(GlobalContext *Ctx) const {
-    Ostream &Str = Ctx->getStrEmit();
-    Str << "undef";
-  }
+  // The target needs to implement this.
+  virtual void emit(GlobalContext *Ctx) const;
 
   using Constant::dump;
   virtual void dump(GlobalContext *Ctx) const {
     Ostream &Str = Ctx->getStrEmit();
     Str << "undef";
   }
 
   static bool classof(const Operand *Operand) {
     return Operand->getKind() == kConstUndef;
   }
@@ skipping 229 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