https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60880
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- I can't see how this assert will ever hit. I looked into the code and promote_duplicated_reg_to_size cannot be called with "size_needed > 1 || (desired_align > align && desired_align > 1)" being true with val also being != const0_rtx.