[llvm][RISCV] Correct the order of statement in insertVSETMTK (#163215)

We need to set register to noreg before shrinking interval

Author: 4vtomat

llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp

@@ -1945,19 +1945,19 @@ bool RISCVInsertVSETVLI::insertVSETMTK(MachineBasicBlock &MBB,
                      .addImm(Log2_32(CurrInfo.getTWiden()) + 1);
 
     Changed = true;
+    Register Reg = Op.getReg();
+    Op.setReg(Register());
+    Op.setIsKill(false);
     if (LIS) {
       LIS->InsertMachineInstrInMaps(*TmpMI);
-      LiveInterval &LI = LIS->getInterval(Op.getReg());
+      LiveInterval &LI = LIS->getInterval(Reg);
 
       // Erase the AVL operand from the instruction.
       LIS->shrinkToUses(&LI);
       // TODO: Enable this once needVSETVLIPHI is supported.
       // SmallVector<LiveInterval *> SplitLIs;
       // LIS->splitSeparateComponents(LI, SplitLIs);
     }
-
-    Op.setReg(RISCV::NoRegister);
-    Op.setIsKill(false);
   }
   return Changed;
 }