return
				}
				prog.RegTo2 = a[2].Reg
				break
			}
			// RISCV64 instructions that reference CSRs with symbolic names.
			if isImm, ok := arch.IsRISCV64CSRO(op); ok {
				if a[0].Type != obj.TYPE_CONST && isImm {
					p.errorf("invalid value for first operand to %s instruction, must be a 5 bit unsigned immediate", op)
					return
				}