re PR tree-optimization/71437 (Performance regression after r235817)

re PR tree-optimization/71437 (Performance regression after r235817)

	PR tree-optimization/71437
	* tree-ssa-dom.c (dom_opt_dom_walker): Remove thread_across_edge
	member function.  Implementation moved into after_dom_children
	member function and into the threader's thread_outgoing_edges
	function.
	(dom_opt_dom_walker::after_dom_children): Simplify by moving
	some code into new thread_outgoing_edges.
	* tree-ssa-threadedge.c (thread_across_edge): Make static and simplify
	definition.  Simplify marker handling (do it here).   Assume we always
	have the available expression and the const/copies tables.
	(thread_outgoing_edges): New function extracted from tree-ssa-dom.c
	and tree-vrp.c
	* tree-ssa-threadedge.h (thread_outgoing_edges): Declare.
	* tree-vrp.c (equiv_stack): No longer file scoped.
	(vrp_dom_walker): New class.
	(vrp_dom_walker::before_dom_children): New member function.
	(vrp_dom_walker::after_dom_children): Likewise.
	(identify_jump_threads):  Setup domwalker.  Use it rather than
	walking edges in a random order by hand.  Simplify setup/finalization.
	(finalize_jump_threads): Remove.
	(vrp_finalize): Do not call identify_jump_threads here.
	(execute_vrp): Do it here instead and call thread_through_all_blocks
	here too.

From-SVN: r246208