[RISCV][Outliner] Use MCRegister. NFC (#128291)

Author: svs-quic

llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.h

@@ -200,7 +200,8 @@ static inline unsigned getVLOpNum(const MCInstrDesc &Desc) {
   return Desc.getNumOperands() - Offset;
 }
 
-static inline unsigned getTailExpandUseRegNo(const FeatureBitset &FeatureBits) {
+static inline MCRegister
+getTailExpandUseRegNo(const FeatureBitset &FeatureBits) {
   // For Zicfilp, PseudoTAIL should be expanded to a software guarded branch.
   // It means to use t2(x7) as rs1 of JALR to expand PseudoTAIL.
   return FeatureBits[RISCV::FeatureStdExtZicfilp] ? RISCV::X7 : RISCV::X6;

llvm/lib/Target/RISCV/RISCVInstrInfo.cpp

@@ -2984,13 +2984,13 @@ static bool isCandidatePatchable(const MachineBasicBlock &MBB) {
 }
 
 static bool isMIReadsReg(const MachineInstr &MI, const TargetRegisterInfo *TRI,
-                         unsigned RegNo) {
+                         MCRegister RegNo) {
   return MI.readsRegister(RegNo, TRI) ||
          MI.getDesc().hasImplicitUseOfPhysReg(RegNo);
 }
 
 static bool isMIModifiesReg(const MachineInstr &MI,
-                            const TargetRegisterInfo *TRI, unsigned RegNo) {
+                            const TargetRegisterInfo *TRI, MCRegister RegNo) {
   return MI.modifiesRegister(RegNo, TRI) ||
          MI.getDesc().hasImplicitDefOfPhysReg(RegNo);
 }
@@ -3005,7 +3005,7 @@ static bool cannotInsertTailCall(const MachineBasicBlock &MBB) {
   // that can be used for expanding PseudoTAIL instruction,
   // then we cannot insert tail call.
   const TargetSubtargetInfo &STI = MBB.getParent()->getSubtarget();
-  unsigned TailExpandUseRegNo =
+  MCRegister TailExpandUseRegNo =
       RISCVII::getTailExpandUseRegNo(STI.getFeatureBits());
   for (const MachineInstr &MI : MBB) {
     if (isMIReadsReg(MI, STI.getRegisterInfo(), TailExpandUseRegNo))