PR tree-optimization/47679
	* tree-ssa-dom.c (expr_hash_elt): Now a class with ctors/dtors,
	methods and private members.
	(avail_exprs_stack): Similarly.  Change type of global
	from a pair of expr_hash_elt_t to the new class.
	(expr_elt_hasher::hash): Corresponding changes.
	(expr_elt_hasher::equal): Similarly.
	(avail_expr_hash): Similarly.
	(pass_dominator::execute): Similarly.
	(dom_opt_dom_walker::thread_across_edge): Similarly.
	(record_cond): Similarly.
	(dom_opt_dom_walker::before_dom_children): Similarly.
	(dom_opt_dom_walker::after_dom_children): Similarly.
	(lookup_avail_expr): Likewise.
	(initialize_hash_element): Now a expr_hash_elt constructor.
	(initialize_hash_element_from_expr): Similarly.
	(free_expr_hash_elt_contents): Now a dtor for class expr_hash_elt.
	(free_expr_hash_elt): Call dtor for the element.
	(remove_local_expressions_from_table): Now the "pop_to_marker"
	method in the available_exprs_stack class.
	(avail_expr_stack::record_expr): Method factored out.
	(print_expr_hash_elt): Now a method in the expr_hash_elt class.
	Fix formatting.
	(hashable_expr_equal_p): Fix formatting.

From-SVN: r227801