Enhance dumps of IVOPTS

Enhance dumps of IVOPTS

	* tree-ssa-loop-ivopts.c (avg_loop_niter): Fix coding style.
	(struct cost_pair): Change inv_expr_id (int) to inv_expr
	(iv_inv_expr_ent *).
	(struct iv_inv_expr_ent): Comment struct fields.
	(sort_iv_inv_expr_ent): New function.
	(struct ivopts_data): Rename inv_expr_id to max_inv_expr_id.
	(struct iv_ca): Replace used_inv_expr and num_used_inv_expr with
	a hash_map between iv_inv_expr_ent and number of usages.
	(niter_for_exit): Fix coding style.
	(tree_ssa_iv_optimize_init): Use renamed variable.
	(determine_base_object): Fix coding style.
	(alloc_iv): Likewise.
	(find_interesting_uses_outside): Likewise.
	(add_candidate_1): Likewise.
	(add_standard_iv_candidates): Likewise.
	(set_group_iv_cost): Replace inv_expr_id with inv_expr.
	(prepare_decl_rtl): Fix coding style.
	(get_address_cost): Likewise.
	(get_shiftadd_cost): Likewise.
	(force_expr_to_var_cost): Likewise.
	(compare_aff_trees): Likewise.
	(get_expr_id): Restructure the function.
	(get_loop_invariant_expr_id): Renamed to
	get_loop_invariant_expr.
	(get_computation_cost_at): Replace usage of inv_expr_id with
	inv_expr.
	(get_computation_cost): Likewise.
	(determine_group_iv_cost_generic): Likewise.
	(determine_group_iv_cost_address): Likewise.
	(iv_period): Fix coding style.
	(iv_elimination_compare_lt): Likewise.
	(may_eliminate_iv): Likewise.
	(determine_group_iv_cost_cond):  Replace usage of inv_expr_id with
	inv_expr.
	(determine_group_iv_costs): Dump invariant expressions.
	(iv_ca_recount_cost): Use the newly added hash_map.
	(iv_ca_set_remove_invariants): Fix coding style.
	(iv_ca_set_add_invariants): Fix coding style.
	(iv_ca_set_no_cp): Utilize the newly added hash_map for used
	invariants.
	(iv_ca_set_cp): Likewise.
	(iv_ca_new): Initialize the newly added hash_map and remove
	initialization of fields.
	(iv_ca_free): Delete the hash_map.
	(iv_ca_dump): Dump invariant expressions.
	(iv_ca_extend): Fix coding style.
	(try_add_cand_for): Likewise.
	(create_new_ivs): Dump information about # of avg iterations and
	# of used invariant expressions.
	(rewrite_use_compare): Fix coding style.
	(free_loop_data): Set default value for max_inv_expr_id.
	* g++.dg/tree-ssa/ivopts-3.C: Change test-case to follow
	the new format of dump output.

From-SVN: r236200