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

src/IceTargetLoweringX8664Traits.h

 //===- subzero/src/IceTargetLoweringX8664Traits.h - x86-64 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 383 matching lines @@
       return RegisterSet::Reg_ax;
     case IceType_i32:
       return RegisterSet::Reg_eax;
     case IceType_i64:
       return RegisterSet::Reg_rax;
     }
   }
 
 public:
   static RegNumT getGprForType(Type Ty, RegNumT RegNum) {
-    assert(RegNum != RegNumT::NoRegister);
+    assert(RegNum.hasValue());
 
     if (!isScalarIntegerType(Ty)) {
       return RegNum;
     }
 
     assert(Ty == IceType_i1 || Ty == IceType_i8 || Ty == IceType_i16 ||
            Ty == IceType_i32 || Ty == IceType_i64);
 
     if (RegNum == RegisterSet::Reg_ah) {
       assert(Ty == IceType_i8);
@@ skipping 308 matching lines @@
   /// The maximum number of arguments to pass in GPR registers
   static constexpr uint32_t X86_MAX_GPR_ARGS = 6;
   /// Whether scalar floating point arguments are passed in XMM registers
   static constexpr bool X86_PASS_SCALAR_FP_IN_XMM = true;
   /// Get the register for a given argument slot in the XMM registers.
   static RegNumT getRegisterForXmmArgNum(uint32_t ArgNum) {
     // TODO(sehr): Change to use the CCArg technique used in ARM32.
     static_assert(RegisterSet::Reg_xmm0 + 1 == RegisterSet::Reg_xmm1,
                   "Inconsistency between XMM register numbers and ordinals");
     if (ArgNum >= X86_MAX_XMM_ARGS) {
-      return RegNumT::NoRegister;
+      return RegNumT();
     }
     return RegNumT::fixme(RegisterSet::Reg_xmm0 + ArgNum);
   }
   /// Get the register for a given argument slot in the GPRs.
   static RegNumT getRegisterForGprArgNum(Type Ty, uint32_t ArgNum) {
     if (ArgNum >= X86_MAX_GPR_ARGS) {
-      return RegNumT::NoRegister;
+      return RegNumT();
     }
     static const RegisterSet::AllRegisters GprForArgNum[] = {
         RegisterSet::Reg_rdi, RegisterSet::Reg_rsi, RegisterSet::Reg_rdx,
         RegisterSet::Reg_rcx, RegisterSet::Reg_r8,  RegisterSet::Reg_r9,
     };
     static_assert(llvm::array_lengthof(GprForArgNum) == X86_MAX_GPR_ARGS,
                   "Mismatch between MAX_GPR_ARGS and GprForArgNum.");
     assert(Ty == IceType_i64 || Ty == IceType_i32);
     return getGprForType(Ty, GprForArgNum[ArgNum]);
   }
@@ skipping 281 matching lines @@
     const char *FldString;   // s, l, or <blank>
   } TypeAttributes[];
 };
 
 using Traits = ::Ice::X8664::TargetX8664Traits;
 } // end of namespace X8664
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGX8664TRAITS_H