2016-01-15  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/66856
	* tree-vect-loop.c (vect_transform_loop): Free SLP instances here.
	* tree-vect-slp.c (vect_free_slp_tree): Decrement stmt reference count.
	(vect_create_new_slp_node): Increment stmt reference count.
	(vect_get_and_check_slp_defs): Make sure stmts are nor already in
	an SLP tree before swapping operands.
	(vect_build_slp_tree): Likewise.
	(destroy_bb_vec_info): Free stmt info after SLP instances.
	* tree-vect-stmts.c (new_stmt_vec_info): Initialize reference count.
	* tree-vectorizer.h (struct _stmt_vec_info): Add num_slp_uses field.
	(STMT_VINFO_NUM_SLP_USES): New macro.

	* gcc.dg/torture/pr66856-1.c: New testcase.
	* gcc.dg/torture/pr66856-2.c: Likewise.

From-SVN: r232435