PR tree-optimization/47679
	* tree-ssa-dom.c (free_edge_info): Factored out of free_all_edge_infos.
	(free_all_edge_infos): Use it.
	(allocate_edge_info): Free preexisting edge info data.
	(pass_dominator::execute): Set up initial edge info structures.
	(dom_opt_dom_walker::thread_across_edge): Pass avail_expr_stack to
	thread_across_edge.
	* tree-ssa-threadedge.c (thread_across_edge): Accept new argument.  If
	non-null, then push/pop markers appropriately.
	* tree-ssa-threadedge.h (thread_across_edge): Update prototype.
	* tree-vrp.c (identify_jump_threads): Pass NULL for new argument to
	thread-across_edge.

From-SVN: r227842