https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55212
--- Comment #54 from Kazumoto Kojima <kkojima at gcc dot gnu.org> --- Created attachment 33657 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33657&action=edit A possible workaround The patch is trying to fix the result of decompose_mem_address so as not to assign INDEX_REG_CLASS to both base and index regs when INDEX_REG_CLASS has one register only.