PR rtl-optimization/27735
	* cfgloopmanip.c (fix_loop_placements, fix_bb_placements, unloop):
	Add new argument to keep track of whether an irreducible region
	was affected.  All callers changed.
	(fix_irreducible_loops): Removed.
	(remove_path): Call mark_irreducible_loops if EDGE_IRREDUCIBLE_LOOP
	flags were invalidated.

	* gcc.dg/loop-unswitch-1.c: New test.

From-SVN: r116582