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

src/IceRegistersARM32.h

 //===- subzero/src/IceRegistersARM32.h - Register information ---*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 86 matching lines @@
   unsigned IsFP64 : 1;
   unsigned IsVec128 : 1;
 #define NUM_ALIASES_BITS 3
   SizeT NumAliases : (NUM_ALIASES_BITS + 1);
   uint16_t Aliases[1 << NUM_ALIASES_BITS];
 #undef NUM_ALIASES_BITS
 } RegTable[Reg_NUM];
 
 static inline void assertValidRegNum(RegNumT RegNum) {
   (void)RegNum;
-  assert(RegNum != RegNumT::NoRegister);
+  assert(RegNum.hasValue());
 }
 
 static inline bool isGPRegister(RegNumT RegNum) {
   RegNum.assertIsValid();
   return RegTable[RegNum].IsGPR;
 }
 
 static constexpr inline SizeT getNumGPRegs() {
   return 0
 #define X(val, encode, name, cc_arg, scratch, preserved, stackptr, frameptr,   \
@@ skipping 99 matching lines @@
   RCARM32_QtoS = RC_Target, // Denotes Q registers that are aliased by S
                             // registers.
   RCARM32_NUM
 };
 
 } // end of namespace RegARM32
 } // end of namespace ARM32
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEREGISTERSARM32_H