PR tree-optimization/31739
	* tree-vrp.c (vrp_val_is_max): New static function.
	(vrp_val_is_min): New static function.
	(set_value_range_to_value): Use TYPE_{MAX,MIN}_VALUE rather than
	copying the node.
	(set_value_range): Use vrp_val_is_{max,min}.
	(extract_range_from_assert): Likewise.
	(extract_range_from_binary_expr): Likewise.
	(extract_range_from_unary_expr): Likewise.
	(dump_value_range, vrp_meet): Likewise.
	(vrp_visit_phi_node): Likewise.
	* tree.c (build_distinct_type_copy): Revert change of 2007-04-27.

From-SVN: r124334