[Bug middle-end/78098] error: interrupt service routine can't be called directly

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78098

--- Comment #10 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to H.J. Lu from comment #9)
> (In reply to Richard Biener from comment #6)
> > Why would we be not able to tailcall in an interupt handler?
> 
> We need to verify that the only instruction in an interrupt handler
> is a tail call to another interrupt handler.  On the other hand,
> this interrupt handler isn't really needed at all.

That can be vefief by fact that the symbol should have only one call (tail
call) and set node->icf_merged == true.