tree-ssa-pre.c (print_pre_expr): Handle NULL expr.

tree-ssa-pre.c (print_pre_expr): Handle NULL expr.

2017-08-01  Richard Biener  <rguenther@suse.de>

	* tree-ssa-pre.c (print_pre_expr): Handle NULL expr.
	(compute_antic): Seed worklist with exit block predecessors.
	* cfganal.c (dfs_find_deadend): For a cycle return the source
	of the edge closing it.

	* gcc.dg/tree-ssa/ssa-dce-3.c: Adjust.
	* gcc.dg/tree-ssa/split-path-5.c: Remove case with just dead
	endless loop.
	* gcc.dg/uninit-23.c: Adjust.

From-SVN: r250767