tree-ssa-dom.c (class edge_info): Changed from a struct to a class.

	* tree-ssa-dom.c (class edge_info): Changed from a struct
	to a class.  Add ctor/dtor, methods and data members.
	(edge_info::edge_info): Renamed from allocate_edge_info.
	Initialize additional members.
	(edge_info::~edge_info): New.
	(free_dom_edge_info): Delete the edge info.
	(record_edge_info): Use new class & associated member functions.
	Tighten forms for testing for edge equivalences.
	(record_temporary_equivalences): Iterate over the simple
	equivalences rather than assuming there's only one per edge.
	(cprop_into_successor_phis): Iterate over the simple
	equivalences rather than assuming there's only one per edge.
	(optimize_stmt): Use operand_equal_p rather than pointer
	equality for mini-DSE code.

From-SVN: r251396