* tree-ssa-threadupdate.c (redirect_edges): Call
create_edge_and_update_destination_phis as needed.
(create_edge_and_update_destination_phis): Accept new BB argument.
All callers updated.
(thread_block): Do not update the profile when threading around
intermediate blocks.
(thread_single_edge): Likewise.
(determine_bb_domination_status): If BB is not a successor of the
loop header, return NONDOMINATING.
(register_jump_thread): Note when we register a jump thread around
an intermediate block.
* tree-ssa-threadedge.c (thread_around_empty_block): New function.
(thread_across_edge): Use it.
* gcc.dg/tree-ssa/ssa-dom-thread-3.c: New test.
From-SVN: r171622
