2013-02-08  Richard Biener  <rguenther@suse.de>

	PR middle-end/56181
	* cfgloop.h (flow_loops_find): Adjust.
	(bb_loop_header_p): Declare.
	* cfgloop.c (bb_loop_header_p): New function split out from ...
	(flow_loops_find): ... here.  Adjust function signature,
	support incremental loop structure update.
	(verify_loop_structure): Cleanup.  Verify a loop is a loop.
	* cfgloopmanip.c (fix_loop_structure): Move ...
	* loop-init.c (fix_loop_structure): ... here.
	(apply_loop_flags): Split out from ...
	(loop_optimizer_init): ... here.
	(fix_loop_structure): Use apply_loop_flags.  Use flow_loops_find
	in incremental mode, only remove dead loops here.

	* gcc.dg/torture/pr56181.c: New testcase.

From-SVN: r195879