2016-01-29  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/69547
	* tree-ssa-dce.c (mark_aliased_reaching_defs_necessary_1):
	Do not mark clobbers necessary.
	(mark_all_reaching_defs_necessary_1): Likewise.

	* g++.dg/tree-ssa/pr69547.C: New testcase.

From-SVN: r232976