Index: cfgexpand.c
===================================================================
--- cfgexpand.c (revision 192696)
+++ cfgexpand.c (working copy)
@@ -3989,6 +3989,12 @@ expand_gimple_basic_block (basic_block b

   do_pending_stack_adjust ();

+  /* If this block has no successors at all, make sure that
+     find_many_sub_basic_blocks does not connect this "dead end"
+     to the rest of the function.  */
+  if (EDGE_COUNT (bb->succs) == 0)
+    expand_builtin_unreachable ();
+
   /* Find the block tail.  The last insn in the block is the insn
      before a barrier and/or table jump insn.  */
   last = get_last_insn ();