https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80707
--- Comment #4 from Peter Bergner <bergner at gcc dot gnu.org> --- David and HJ, the following patch fixes the ICE Markus reported, so can you try the following patch to see if it fixes your bootstrap issues? Index: tree-cfg.c =================================================================== --- tree-cfg.c (revision 247845) +++ tree-cfg.c (working copy) @@ -1684,6 +1684,10 @@ group_case_labels_stmt (gswitch *stmt) || (EDGE_COUNT (base_bb->succs) == 0 && gimple_seq_unreachable_p (bb_seq (base_bb)))) { + edge e; + if (base_bb != default_bb + && (e = find_edge (gimple_bb (stmt), base_bb)) != NULL) + remove_edge_and_dominated_blocks (e); gimple_switch_set_label (stmt, i, NULL_TREE); i++; new_size--;