https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79354
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Looking at tmp-mddump.md, the only other insn that emits the stxssp instruction is movsf_hardfloat and that uses wb constraint for the input_operand and only uses wu constraint for stxsspx, while movsi_from_sf uses wu constraint for both stxssp and stxsspx. Using wb instead of wu for movsi_from_sf constraint on the stxssp alternative fixes the bug.
