https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99680
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- I was worried that letters that introduce multi-letter constraints followed by '\0' could be a problem too. Or do we rely on those being dropped already earlier? Something like "=B" on x86_64 etc. In what I've tried it was dropped during vregs pass though. And when cn already is CONSTRAINT__UNKNOWN, performing checks whether to set it to CONSTRAINT__UNKNOWN is just wasted time.
