2015-04-28  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/65851
	* tree-ssa-ccp.c (set_lattice_value): Perform a meet when
	changing CONSTANT to CONSTANT non-copy.  Get new_val by reference.
	(ccp_lattice_meet): Remove stray argument.  Use operand_equal_p
	rather than simple_cst_equal as the latter doesn't handle COMPLEX_CST.
	(ccp_visit_phi_node): Adjust.
	(evaluate_stmt): For simplifications to SSA names return its
	lattice value if that isn't VARYING.  Return immediately when
	simplified to a constant.
	(visit_assignment): Adjust.
	(ccp_visit_stmt): Likewise.

	* g++.dg/torture/pr65851.C: New testcase.

From-SVN: r222510