GlobalISel: Use Register and update comment physical register syntax

Author: arsenm

llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp

@@ -106,8 +106,8 @@ MachineInstrBuilder MachineIRBuilder::buildConstDbgValue(const Constant &C,
   } else if (auto *CFP = dyn_cast<ConstantFP>(&C)) {
     MIB.addFPImm(CFP);
   } else {
-    // Insert %noreg if we didn't find a usable constant and had to drop it.
-    MIB.addReg(0U);
+    // Insert $noreg if we didn't find a usable constant and had to drop it.
+    MIB.addReg(Register());
   }
 
   MIB.addImm(0).addMetadata(Variable).addMetadata(Expr);