2012-04-03 Richard Guenther <rguenther@suse.de>

2012-04-03  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/52808
	* tracer.c (tail_duplicate): Return whether we have duplicated
	any block.
	(tracer): If we have duplicated any block, cleanup the CFG.
	* cfghooks.c (duplicate_block): If we duplicated a loop
	header but not its loop, destroy the loop because it now has
	multiple entries.
	* tree-ssa-threadupdate.c (thread_through_loop_header): Tell
	the cfg manipulation routines we are not creating a multiple
	entry loop.

	* gcc.dg/pr52808.c: New testcase.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@186104 138bc75d-0d04-0410-961f-82ee72b054a4