tree-ssa-pre.c (insert_into_preds_of_block): Before inserting a PHI ask VN if it is already available.

2008-08-21  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-pre.c (insert_into_preds_of_block): Before inserting
	a PHI ask VN if it is already available.
	* tree-ssa-sccvn.h (vn_phi_lookup): Declare.
	* tree-ssa-sccvn.c (vn_phi_lookup): Export.

From-SVN: r139388