* tree-ssa-threadupdate.c (struct redirection_data): New field
	intermediate_edge.
	(THREAD_TARGET2): Define.
	(redirection_data_eq): Also check that the intermediate edge is
	equal.
	(lookup_redirection_data): Drop useless argument.  Extract the
	outgoing_edge and intermediate edge from E.  Callers updated.
	(copy_phi_args, update_destination_phis): New functions.
	(fix_duplicate_block_edges): Likewise.
	(create_edge_and_update_destination_phis): Duplicate all the edges
	hung off e->aux.  Use copy_phi_args.
	(create_duplicates): Use fix_duplicate_block_edges.
	(fixup_template_block): Likewise.
	(redirect_edges): If necessary, redirect the joiner block's incoming
	edge to the duplicate of the joiner block.
	(thread_block): Don't muck up loops when threading through a joiner
	block.
	(thread_through_loop_header): Handle threading through a joiner
	block.
	(mark_threaded_blocks, register_jump_thread): Likewise.
	* tree-flow.h (register_jump_thread): Add new argument.  Callers
	updated.
	* tree-ssa-threadedge.c (phi_args_equal_on_edges): New function.
	(thread_across_edge): Handle threading through a joiner block.
	

	
	* gcc.dg/builtin-object-size-1.c: Update to handle changes from
	improved jump threading.
	* gcc.dg/builtin-object-size-2.c: Likewise.
	* gcc.dg/tree-ssa/20030728-1.c: Likewise.

From-SVN: r175114