2012-04-11  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/52912
	* tree-ssa-threadupdate.c (thread_block): Tell the cfg
	manipulation code we are threading through a loop header
	to an exit destination.

	* gcc.dg/torture/pr52912.c: New testcase.

From-SVN: r186303