https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116389
--- Comment #6 from Jeffrey A. Law <law at gcc dot gnu.org> --- Sorry should have written "is _not_ a reasonable assessment" in my prior message. RA does assess validity and there's nothing special about avr here and paradoxicals, unless the backend is doing something incorrect. You really need to debug why IRA is making an invalid assignment.
