[RISCV] Use MCRegister for variables returned from AllocateReg. NFC

Avoids a cast from Register to MCRegister for the CCValAssign
functions.

Author: topperc

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -19087,7 +19087,7 @@ static bool CC_RISCVAssign2XLen(unsigned XLen, CCState &State, CCValAssign VA1,
       State.getMachineFunction().getSubtarget<RISCVSubtarget>();
   ArrayRef<MCPhysReg> ArgGPRs = RISCV::getArgGPRs(STI.getTargetABI());
 
-  if (Register Reg = State.AllocateReg(ArgGPRs)) {
+  if (MCRegister Reg = State.AllocateReg(ArgGPRs)) {
     // At least one half can be passed via register.
     State.addLoc(CCValAssign::getReg(VA1.getValNo(), VA1.getValVT(), Reg,
                                      VA1.getLocVT(), CCValAssign::Full));
@@ -19108,7 +19108,7 @@ static bool CC_RISCVAssign2XLen(unsigned XLen, CCState &State, CCValAssign VA1,
     return false;
   }
 
-  if (Register Reg = State.AllocateReg(ArgGPRs)) {
+  if (MCRegister Reg = State.AllocateReg(ArgGPRs)) {
     // The second half can also be passed via register.
     State.addLoc(
         CCValAssign::getReg(ValNo2, ValVT2, Reg, LocVT2, CCValAssign::Full));
@@ -19230,7 +19230,7 @@ bool RISCV::CC_RISCV(const DataLayout &DL, RISCVABI::ABI ABI, unsigned ValNo,
 
   if (UseGPRForF16_F32 && (ValVT == MVT::f16 || ValVT == MVT::bf16 ||
                            (ValVT == MVT::f32 && XLen == 64))) {
-    Register Reg = State.AllocateReg(ArgGPRs);
+    MCRegister Reg = State.AllocateReg(ArgGPRs);
     if (Reg) {
       LocVT = XLenVT;
       State.addLoc(
@@ -19283,7 +19283,7 @@ bool RISCV::CC_RISCV(const DataLayout &DL, RISCVABI::ABI ABI, unsigned ValNo,
     // GPRs, split between a GPR and the stack, or passed completely on the
     // stack. LowerCall/LowerFormalArguments/LowerReturn must recognise these
     // cases.
-    Register Reg = State.AllocateReg(ArgGPRs);
+    MCRegister Reg = State.AllocateReg(ArgGPRs);
     if (!Reg) {
       unsigned StackOffset = State.AllocateStack(8, Align(8));
       State.addLoc(
@@ -19292,7 +19292,7 @@ bool RISCV::CC_RISCV(const DataLayout &DL, RISCVABI::ABI ABI, unsigned ValNo,
     }
     LocVT = MVT::i32;
     State.addLoc(CCValAssign::getCustomReg(ValNo, ValVT, Reg, LocVT, LocInfo));
-    Register HiReg = State.AllocateReg(ArgGPRs);
+    MCRegister HiReg = State.AllocateReg(ArgGPRs);
     if (HiReg) {
       State.addLoc(
           CCValAssign::getCustomReg(ValNo, ValVT, HiReg, LocVT, LocInfo));
@@ -19340,7 +19340,7 @@ bool RISCV::CC_RISCV(const DataLayout &DL, RISCVABI::ABI ABI, unsigned ValNo,
   }
 
   // Allocate to a register if possible, or else a stack slot.
-  Register Reg;
+  MCRegister Reg;
   unsigned StoreSizeBytes = XLen / 8;
   Align StackAlign = Align(XLen / 8);