case obj.TYPE_REG:
				prog.Reg = p.getRegister(prog, op, &a[1])
			default:
				prog.AddRestSource(a[1])
			}
		case sys.RISCV64:
			// RISCV64 instructions with one input and two outputs.
			if arch.IsRISCV64AMO(op) {
				prog.From = a[0]
				prog.To = a[1]
				if a[2].Type != obj.TYPE_REG {
					p.errorf("invalid addressing modes for third operand to %s instruction, must be register", op)
					return
				}