re PR tree-optimization/64191 (indirect clobbers messes up dead code elimination in loop calling dtor)

2014-12-10  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/64191
	* tree-ssa-dce.c (mark_stmt_if_obviously_necessary): Do not
	mark clobbers as necessary.
	(eliminate_unnecessary_stmts): Keep clobbers live if we can.

	* g++.dg/pr64191.C: Make sure we can DCE empty loops with
	indirect clobbers.

From-SVN: r218566