Subzero: Prototype to make use of RegNumT::No Register more concise

src/IceTargetLoweringX8632Traits.h

 //===- subzero/src/IceTargetLoweringX8632Traits.h - x86-32 traits -*- C++ -*-=//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 357 matching lines @@
     case IceType_i16:
       return RegisterSet::Reg_ax;
     case IceType_i32:
       return RegisterSet::Reg_eax;
     }
   }
 
 public:
   // Return a register in RegNum's alias set that is suitable for Ty.
   static RegNumT getGprForType(Type Ty, RegNumT RegNum) {
-    assert(RegNum != RegNumT::NoRegister);
+    assert(RegNum.hasValue());
 
     if (!isScalarIntegerType(Ty)) {
       return RegNum;
     }
 
     // [abcd]h registers are not convertible to their ?l, ?x, and e?x versions.
     switch (RegNum) {
     default:
       break;
     case RegisterSet::Reg_ah:
@@ skipping 602 matching lines @@
 
   static uint8_t InstSegmentPrefixes[];
 };
 
 using Traits = ::Ice::X8632::TargetX8632Traits;
 } // end of namespace X8632
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGX8632TRAITS_H