https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91233
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- >They don't have hi and lo registers available (at least w/o dsp extension for >time being). So don't use them if they are not present. MIPSr6 seems to break backwards compatible in many ways, this is just one of them.