* tree-ssa-threadupdate.c (create_block_for_threading): Request

	* tree-ssa-threadupdate.c (create_block_for_threading):  Request
	that no outgoing edges be left in the duplicate block.  Do no
	update information on outgoing edges or PHI nodes in target
	blocks here.
	(remove_ctrl_stmt_and_useless_edges): Renamed from
	remove_last_stmt_and_useless_edges.  Handle case where the
	block is empty or has no control statements.  Do not update edge
	flags here.
	(thread_block): Create a template block rather than copying the
	original block every time.  Create outgoing edges from the
	duplicate blocks and update PHIs at the target of the outgoing
	edges here.  Fix edge flags for the original block if necessary.
	* cfghooks (duplicate_block): No longer assert that the original
	block has incoming edges.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@88267 138bc75d-0d04-0410-961f-82ee72b054a4