2015-05-12  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/37021
	* tree-vectorizer.h (struct _slp_tree): Add two_operators flag.
	(SLP_TREE_TWO_OPERATORS): New define.
	* tree-vect-slp.c (vect_create_new_slp_node): Initialize
	SLP_TREE_TWO_OPERATORS.
	(vect_build_slp_tree_1): Allow two mixing plus/minus in an
	SLP node.
	(vect_build_slp_tree): Adjust.
	(vect_analyze_slp_cost_1): Likewise.
	(vect_schedule_slp_instance): Vectorize mixing plus/minus by
	emitting two vector stmts and mixing the results.

	* gcc.target/i386/vect-addsub.c: New testcase.

From-SVN: r223059