https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77938
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> --- I think the only way we can improve this is tracking liveness with CLOBBERs (but that relies on CLOBBERs being present). Like walking dominators looking for CLOBBERs (or computing full data-flow for the desired set of vars, see cfgexpand.c:add_scope_conflicts how this works with CLOBBERs).
