2015-12-16  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/68870
	* tree-cfgcleanup.c (cleanup_control_expr_graph): Add first_p
	parameter, if set only perform trivial constant folding.
	Queue other blocks with conditions for later processing.
	(cleanup_control_flow_bb): Add first_p parameter and pass it through.
	(cleanup_tree_cfg_1): Pass true for the first iteration
	cleanup_control_expr_graph.

	* gcc.dg/torture/pr68870.c: New testcase.

From-SVN: r231695