If we harden a compare at the end of a block with an edge to the
abnormal dispatch block, it won't have a single successor. Arrange to
split the block at its final stmt so as to have a single succ.
for gcc/ChangeLog
PR middle-end/104975
* gimple-harden-conditionals.cc
(pass_harden_compares::execute): Force split in case of
multiple edges.