These function attributes are supported by the m68k back end:
Use this attribute to indicate that the specified function is an interrupt handler. The compiler generates function entry and exit sequences suitable for use in an interrupt handler when this attribute is present. Either name may be used.
Use this attribute on fido, a subarchitecture of the m68k, to indicate
that the specified function is an interrupt handler that is designed
to run as a thread. The compiler omits generate prologue/epilogue
sequences and replaces the return instruction with a
instruction. This attribute is available only on fido.