Backport from tree-ssa (relevant changes only):
	2003-12-18  Zdenek Dvorak  <rakdver@atrey.karlin.mff.cuni.cz>

	* et-forest.h (et_forest_create, et_forest_delete,
	et_forest_add_node, et_forest_add_edge, et_forest_remove_node,
	et_forest_remove_edge, et_forest_parent,
	et_forest_common_ancestor, et_forest_node_value,
	et_forest_enumerate_sons): Declarations removed.
	(struct et_node): New.
	(et_new_tree, et_free_tree, et_set_father, et_split, et_nca,
	et_below): Declare.
	* et-forest.c (struct et_forest_occurrence, struct et_forest,
	struct et_forest_node): Removed.
	(et_forest_create, et_forest_delete,
	et_forest_add_node, et_forest_add_edge, et_forest_remove_node,
	et_forest_remove_edge, et_forest_parent,
	et_forest_common_ancestor, et_forest_node_value,
	et_forest_enumerate_sons, splay, remove_all_occurrences,
	find_leftmost_node, find_rightmost_node, calculate_value): Removed.
	(struct et_occ): New.
	(et_nodes, et_occurences): New.
	(set_depth, set_depth_add, set_prev, set_next, et_recomp_min,
	et_check_occ_sanity, et_check_sanity, et_check_tree_sanity,
	record_path_before_1, record_path_before, check_path_after_1,
	check_path_after, et_splay, et_new_occ, et_new_tree,
	et_free_tree, et_set_father, et_split, et_nca, et_below): New.
	* basic-block.h (struct basic_block_def): New field dom.
	(struct dominance_info): Type removed.
	(calculate_dominance_info, free_dominance_info,
	nearest_common_dominator, set_immediate_dominator,
	get_immediate_dominator, dominated_by_p, get_dominated_by,
	add_to_dominance_info, delete_from_dominance_info,
	recount_dominator, redirect_immediate_dominators,
	iterate_fix_dominators, verify_dominators): Declarations
	changed.
	(enum dom_state): New.
	(dom_computed): New variable.
	(first_dom_son, next_dom_son): Declare.
	* dominance.c (struct dominance_info): Removed.
	(BB_NODE, SET_BB_NODE): Removed.
	(calculate_dominance_info, free_dominance_info,
	nearest_common_dominator, set_immediate_dominator,
	get_immediate_dominator, dominated_by_p, get_dominated_by,
	add_to_dominance_info, delete_from_dominance_info,
	recount_dominator, redirect_immediate_dominators,
	iterate_fix_dominators, verify_dominators,
	debug_dominance_info): Work over new datastructure.  Access
	dominance datastructures through CFG.
	(assign_dfs_numbers, compute_dom_fast_query, first_dom_son,
	next_dom_son): New.
	* bt-load.c (dom): Variable removed.
	(augment_live_range, combine_btr_defs, migrate_btr_def,
	migrate_btr_defs, branch_target_load_optimize): Updated for the
	new interface for dominance information.
	* cfg.c {exit_entry_blocks): Update initializer.
	* cfglayout.c (copy_bbs): Removed loops argument. Updated for
	the new interface for dominance information.
	* cfglayout.h (copy_bbs): Declaration changed.
	* cfgloop.c (flow_loop_pre_header_find, flow_loops_cfg_dump,
	flow_loop_scan, canonicalize_loop_headers, flow_loops_find): Updated
	for the new interface for dominance information.
	(flow_loop_scan): Loops argument removed.
	(flow_loops_free): Don't release dominators.
	* cfgloop.h (struct cfg): Dom field removed.
	(flow_loop_scan, loop_split_edge_with, simple_loop_p,
	just_once_each_iteration_p, split_loop_bb): Declaration changed.
	* cfgloopanal.c (simple_loop_exit_p, simple_increment,
	just_once_each_iteration_p, simple_loop_p): Remove loops argument.
	Updated for the new interface for dominance information.
	* cfgloopmanip.c (remove_bbs, find_path, create_preheader,
	split_loop_bb, loopify, duplicate_loop_to_header_edge,
	force_single_succ_latches, loop_split_edge_with): Ditto.
	* gcse.c (dominators): Variable removed.
	(free_code_hoist_mem, compute_code_hoist_data, hoist_code):
	Updated for the new interface for dominance information.
	* ifcvt.c (post_dominators): Variable removed.
	(mark_loop_exit_edges, merge_if_block, find_if_header,
	find_cond_trap, find_if_case_1, find_if_case_2, if_convert):
	Updated for the new interface for dominance information.
	* loop-init.c (rtl_loop_optimizer_init,
	rtl_loop_optimizer_finalize): Ditto.
	* loop-unroll.c (decide_peel_simple, decide_peel_once_rolling,
	decide_peel_completely, decide_unroll_stupid,
	decide_unroll_constant_iterations,
	decide_unroll_runtime_iterations): Loops argument removed.
	Updated for the new interface for dominance information.
	(unroll_and_peel_loops, peel_loops_completely,
	unroll_loop_runtime_iterations): Updated for the new interface for
	dominance information.
	* loop-unswitch.c (may_unswitch_on_p, unswitch_loops,
	unswitch_single_loop, unswitch_loop): Updated for the new
	interface for dominance information.
	* predict.c (process_note_predictions, process_note_prediction,
	estimate_probability, note_prediction_to_br_prob): Ditto.
	* sched-rgn.c (find_rgns, init_regions): Ditto.
	* toplev.c (rest_of_handle_branch_prob): Free the dominators.

From-SVN: r75226