- expressions in the machine description.
-
- As a special exception, registers whose class is NO_REGS are
- not accepted by `register_operand'. The reason for this change
- is to allow the representation of special architecture artifacts
- (such as a condition code register) without extending the rtl
- definitions. Since registers of class NO_REGS cannot be used
- as registers in any case where register classes are examined,
- it is most consistent to keep this function from accepting them. */