* 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