2016-03-03  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/55936
	* tree-vrp.c (compare_name_with_value): Add use_equiv_p
	parameter and guard unsafe equivalence use.
	(vrp_evaluate_conditional_warnv_with_ops): Always use
	safe equivalences but not via the quadratic compare_names
	helper.

	* gcc.dg/tree-ssa/vrp06.c: Remove XFAIL.

From-SVN: r233928