tree-vrp.c (evrp_dom_walker::before_dom_children): Ignore backedges when identifying the single predecessor to take conditional...

2016-10-24  Richard Biener  <rguenther@suse.de>

	* tree-vrp.c (evrp_dom_walker::before_dom_children): Ignore
	backedges when identifying the single predecessor to take
	conditional info from.  Use SCEV to get at ranges for loop IVs.
	* lto-streamer-out.c (lto_write_mode_table): CSE inner mode to
	avoid false warning.

	* gcc.dg/tree-ssa/cunroll-13.c: Disable EVRP.
	* gcc.dg/tree-ssa/pr21458.c: Likewise.
	* gcc.dg/tree-ssa/pr21458-2.c: New testcase for EVRP.

From-SVN: r241470