tree-ssa-sccvn.c (vn_reference_lookup_3): Avoid redundant lookups, make looking through aggregate copies stronger.

2011-08-11  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-sccvn.c (vn_reference_lookup_3): Avoid redundant
	lookups, make looking through aggregate copies stronger.

	* g++.dg/tree-ssa/pr41186.C: Un-XFAIL.

From-SVN: r177672