https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68695
--- Comment #14 from Alexandre Oliva <aoliva at gcc dot gnu.org> --- The reason we don't coalesce on s390 is that there's no PROMOTE_MODE defined there, so i_1 and j_2 promote to SImode, whereas x_3 and y_4, being function arguments, promote to DImode as per s390_promote_function_mode.
