https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68695
--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> --- So for some reason no SSA coalescing is done for s390x here (compared to x86_64). That's the thing to look at, possibly related to some of the required parameter coalescing / default def coalescing hackery.
