https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97437
--- Comment #6 from Segher Boessenkool <segher at gcc dot gnu.org> --- I forgot to add: subtract immediate is the same as add immediate for us, we don't change the sense of the carry bit to a "borrow bit" (and instead, we have a subtract-from-immediate). But this doesn't change much at all to the situation here.