2011-09-07  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/50319
	* tree-if-conv.c (set_bb_predicate): Assert we only set
	canonical predicates.
	(add_to_predicate_list): Simplify.  Allow TRUTH_NOT_EXPR
	around canonical predicates.
	(predicate_bbs): Do not re-gimplify already canonical
	predicates.  Properly unshare them though.
	(find_phi_replacement_condition): Simplify.

From-SVN: r178638