2008-08-29  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/37207
	* tree-vrp.c (extract_range_from_binary_expr): Also try
	to constant fold if only one of the operands is a constant.

	* gcc.dg/tree-ssa/vrp46.c: New testcase.

From-SVN: r139754