2 * Scheduling algorithms.
3 * Just a simple list scheduling algorithm is here.
5 * @author Sebastian Hack
23 #include "iredges_t.h"
28 #include "irprintf_t.h"
31 #include "besched_t.h"
34 #include "belistsched.h"
38 #define MAX(x,y) ((x) > (y) ? (x) : (y))
39 #define MIN(x,y) ((x) < (y) ? (x) : (y))
42 * Scheduling environment for the whole graph.
44 typedef struct _sched_env_t {
45 const list_sched_selector_t *selector; /**< The node selector. */
46 const arch_env_t *arch_env; /**< The architecture enviromnent. */
47 const ir_graph *irg; /**< The graph to schedule. */
48 void *selector_env; /**< A pointer to give to the selector. */
53 * Ugly global variable for the compare function
54 * since qsort(3) does not pass an extra pointer.
56 static ir_node *curr_bl = NULL;
58 static int cmp_usage(const void *a, const void *b)
60 struct trivial_sched_env *env;
65 res = is_live_end(env->curr_bl, a) - is_live_end(env->curr_bl, b);
68 * One of them is live at the end of the block.
69 * Then, that one shall be scheduled at after the other
80 * The trivial selector:
81 * Just assure that branches are executed last, otherwise select
82 * the first node ready.
84 static ir_node *trivial_select(void *block_env, nodeset *ready_set)
86 const arch_env_t *arch_env = block_env;
90 /* assure that branches and constants are executed last */
91 for (irn = nodeset_first(ready_set); irn; irn = nodeset_next(ready_set)) {
92 arch_irn_class_t irn_class = arch_irn_classify(arch_env, irn);
94 if (irn_class != arch_irn_class_branch && (const_last ? (irn_class != arch_irn_class_const) : 1)) {
95 nodeset_break(ready_set);
100 /* assure that constants are executed before branches */
102 for (irn = nodeset_first(ready_set); irn; irn = nodeset_next(ready_set)) {
103 if (arch_irn_classify(arch_env, irn) != arch_irn_class_branch) {
104 nodeset_break(ready_set);
111 /* at last: schedule branches */
112 irn = nodeset_first(ready_set);
113 nodeset_break(ready_set);
118 static void *trivial_init_graph(const list_sched_selector_t *vtab, const arch_env_t *arch_env, ir_graph *irg)
120 return (void *) arch_env;
123 static void *trivial_init_block(void *graph_env, ir_node *bl)
128 static INLINE int must_appear_in_schedule(const list_sched_selector_t *sel, void *block_env, const ir_node *irn)
132 if(sel->to_appear_in_schedule)
133 res = sel->to_appear_in_schedule(block_env, irn);
135 return res || to_appear_in_schedule(irn) || be_is_Keep(irn) || be_is_RegParams(irn);
138 static const list_sched_selector_t trivial_selector_struct = {
147 const list_sched_selector_t *trivial_selector = &trivial_selector_struct;
149 typedef struct _usage_stats_t {
151 struct _usage_stats_t *next;
153 int uses_in_block; /**< Number of uses inside the current block. */
154 int already_consumed; /**< Number of insns using this value already
159 const list_sched_selector_t *vtab;
160 const arch_env_t *arch_env;
161 } reg_pressure_main_env_t;
165 const reg_pressure_main_env_t *main_env;
167 nodeset *already_scheduled;
168 } reg_pressure_selector_env_t;
170 static INLINE usage_stats_t *get_or_set_usage_stats(reg_pressure_selector_env_t *env, ir_node *irn)
172 usage_stats_t *us = get_irn_link(irn);
175 us = obstack_alloc(&env->obst, sizeof(us[0]));
177 us->already_consumed = 0;
178 us->max_hops = INT_MAX;
179 us->next = env->root;
181 set_irn_link(irn, us);
187 static INLINE usage_stats_t *get_usage_stats(ir_node *irn)
189 usage_stats_t *us = get_irn_link(irn);
190 assert(us && "This node must have usage stats");
194 static int max_hops_walker(reg_pressure_selector_env_t *env, ir_node *irn, ir_node *curr_bl, int depth, unsigned visited_nr)
196 ir_node *bl = get_nodes_block(irn);
198 * If the reached node is not in the block desired,
199 * return the value passed for this situation.
201 if(get_nodes_block(irn) != bl)
202 return block_dominates(bl, curr_bl) ? 0 : INT_MAX;
205 * If the node is in the current block but not
206 * yet scheduled, we keep on searching from that node.
208 if(!nodeset_find(env->already_scheduled, irn)) {
211 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
212 ir_node *operand = get_irn_n(irn, i);
214 if(get_irn_visited(operand) < visited_nr) {
217 set_irn_visited(operand, visited_nr);
218 tmp = max_hops_walker(env, operand, bl, depth + 1, visited_nr);
227 * If the node is in the current block and scheduled, return
228 * the depth which indicates the number of steps to the
229 * region of scheduled nodes.
234 static int compute_max_hops(reg_pressure_selector_env_t *env, ir_node *irn)
236 ir_node *bl = get_nodes_block(irn);
237 ir_graph *irg = get_irn_irg(bl);
240 const ir_edge_t *edge;
242 foreach_out_edge(irn, edge) {
243 ir_node *user = get_edge_src_irn(edge);
244 unsigned visited_nr = get_irg_visited(irg) + 1;
247 set_irg_visited(irg, visited_nr);
248 max_hops = max_hops_walker(env, user, irn, 0, visited_nr);
249 res = MAX(res, max_hops);
255 static void *reg_pressure_graph_init(const list_sched_selector_t *vtab, const arch_env_t *arch_env, ir_graph *irg)
257 reg_pressure_main_env_t *main_env = xmalloc(sizeof(main_env[0]));
259 main_env->arch_env = arch_env;
260 main_env->vtab = vtab;
261 irg_walk_graph(irg, firm_clear_link, NULL, NULL);
266 static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
269 reg_pressure_selector_env_t *env = xmalloc(sizeof(env[0]));
271 obstack_init(&env->obst);
272 env->already_scheduled = new_nodeset(32);
274 env->main_env = graph_env;
277 * Collect usage statistics.
279 sched_foreach(bl, irn) {
280 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
283 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
284 ir_node *op = get_irn_n(irn, i);
285 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
286 usage_stats_t *us = get_or_set_usage_stats(env, irn);
287 if(is_live_end(bl, op))
288 us->uses_in_block = 99999;
299 static void reg_pressure_block_free(void *block_env)
301 reg_pressure_selector_env_t *env = block_env;
304 for(us = env->root; us; us = us->next)
305 set_irn_link(us->irn, NULL);
307 obstack_free(&env->obst, NULL);
308 del_nodeset(env->already_scheduled);
312 static int get_result_hops_sum(reg_pressure_selector_env_t *env, ir_node *irn)
315 if(get_irn_mode(irn) == mode_T) {
316 const ir_edge_t *edge;
318 foreach_out_edge(irn, edge)
319 res += get_result_hops_sum(env, get_edge_src_irn(edge));
322 else if(mode_is_data(get_irn_mode(irn)))
323 res = compute_max_hops(env, irn);
329 static INLINE int reg_pr_costs(reg_pressure_selector_env_t *env, ir_node *irn)
334 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
335 ir_node *op = get_irn_n(irn, i);
337 if(must_appear_in_schedule(env->main_env->vtab, env, op))
338 sum += compute_max_hops(env, op);
341 sum += get_result_hops_sum(env, irn);
346 static ir_node *reg_pressure_select(void *block_env, nodeset *ready_set)
348 reg_pressure_selector_env_t *env = block_env;
349 ir_node *irn, *res = NULL;
350 int curr_cost = INT_MAX;
352 assert(nodeset_count(ready_set) > 0);
354 for (irn = nodeset_first(ready_set); irn; irn = nodeset_next(ready_set)) {
356 Ignore branch instructions for the time being.
357 They should only be scheduled if there is nothing else.
359 if (arch_irn_classify(env->main_env->arch_env, irn) != arch_irn_class_branch) {
360 int costs = reg_pr_costs(env, irn);
361 if (costs <= curr_cost) {
369 There was no result so we only saw a branch.
374 res = nodeset_first(ready_set);
375 nodeset_break(ready_set);
377 assert(res && "There must be a node scheduled.");
380 nodeset_insert(env->already_scheduled, res);
384 static const list_sched_selector_t reg_pressure_selector_struct = {
385 reg_pressure_graph_init,
386 reg_pressure_block_init,
389 reg_pressure_block_free,
393 const list_sched_selector_t *reg_pressure_selector = ®_pressure_selector_struct;
395 static void list_sched_block(ir_node *block, void *env_ptr);
397 void list_sched(const arch_env_t *arch_env, ir_graph *irg)
401 memset(&env, 0, sizeof(env));
402 env.selector = arch_env->isa->impl->get_list_sched_selector(arch_env->isa);
403 env.arch_env = arch_env;
406 if(env.selector->init_graph)
407 env.selector_env = env.selector->init_graph(env.selector, arch_env, irg);
409 /* Assure, that the out edges are computed */
412 /* Schedule each single block. */
413 irg_block_walk_graph(irg, list_sched_block, NULL, &env);
415 if(env.selector->finish_graph)
416 env.selector->finish_graph(env.selector_env);
421 * Environment for a block scheduler.
423 typedef struct _block_sched_env_t {
426 nodeset *already_scheduled;
428 const list_sched_selector_t *selector;
429 void *selector_block_env;
430 DEBUG_ONLY(firm_dbg_module_t *dbg;)
434 * Try to put a node in the ready set.
435 * @param env The block scheduler environment.
436 * @param irn The node to make ready.
437 * @return 1, if the node could be made ready, 0 else.
439 static INLINE int make_ready(block_sched_env_t *env, ir_node *irn)
443 /* Blocks cannot be scheduled. */
448 * Check, if the given ir node is in a different block as the
449 * currently scheduled one. If that is so, don't make the node ready.
451 if(env->block != get_nodes_block(irn))
454 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
455 ir_node *op = get_irn_n(irn, i);
457 /* if irn is an End we have keep-alives and op might be a block, skip that */
459 assert(get_irn_op(irn) == op_End);
463 /* If the operand is local to the scheduled block and not yet
464 * scheduled, this nodes cannot be made ready, so exit. */
465 if(!nodeset_find(env->already_scheduled, op) && get_nodes_block(op) == env->block)
469 DBG((env->dbg, LEVEL_2, "\tmaking ready: %+F\n", irn));
470 nodeset_insert(env->ready_set, irn);
476 * Check, if a node is ready in a block schedule.
477 * @param env The block schedule environment.
478 * @param irn The node to check for.
479 * @return 1 if the node was ready, 0 if not.
481 #define is_ready(env,irn) \
482 (nodeset_find((env)->ready_set, irn) != NULL)
485 * Check, if a node has already been schedules.
486 * @param env The block schedule environment.
487 * @param irn The node to check for.
488 * @return 1 if the node was already scheduled, 0 if not.
490 #define is_scheduled(env,irn) \
491 (nodeset_find((env)->already_scheduled, irn) != NULL)
494 * Try, to make all users of a node ready.
495 * In fact, a usage node can only be made ready, if all its operands
496 * have already been scheduled yet. This is checked my make_ready().
497 * @param env The block schedule environment.
498 * @param irn The node, which usages (successors) are to be made ready.
500 static INLINE void make_users_ready(block_sched_env_t *env, ir_node *irn)
502 const ir_edge_t *edge;
504 foreach_out_edge(irn, edge) {
505 ir_node *user = edge->src;
507 make_ready(env, user);
512 * Compare to nodes using pointer equality.
513 * @param p1 Node one.
514 * @param p2 Node two.
515 * @return 0 if they are identical.
517 static int node_cmp_func(const void *p1, const void *p2)
523 * Append an instruction to a schedule.
524 * @param env The block scheduling environment.
525 * @param irn The node to add to the schedule.
526 * @return The given node.
528 static ir_node *add_to_sched(block_sched_env_t *env, ir_node *irn)
530 /* If the node consumes/produces data, it is appended to the schedule
531 * list, otherwise, it is not put into the list */
532 if(must_appear_in_schedule(env->selector, env->selector_block_env, irn)) {
533 sched_info_t *info = get_irn_sched_info(irn);
534 INIT_LIST_HEAD(&info->list);
536 sched_add_before(env->block, irn);
538 DBG((env->dbg, LEVEL_2, "\tadding %+F\n", irn));
541 /* Insert the node in the set of all already scheduled nodes. */
542 nodeset_insert(env->already_scheduled, irn);
544 /* Remove the node from the ready set */
545 if(nodeset_find(env->ready_set, irn))
546 nodeset_remove(env->ready_set, irn);
552 * Add the proj nodes of a tuple-mode irn to the schedule immediately
553 * after the tuple-moded irn. By pinning the projs after the irn, no
554 * other nodes can create a new lifetime between the tuple-moded irn and
555 * one of its projs. This should render a realistic image of a
556 * tuple-moded irn, which in fact models a node which defines multiple
559 * @param irn The tuple-moded irn.
560 * @param list The schedule list to append all the projs.
561 * @param time The time step to which the irn and all its projs are
563 * @param obst The obstack the scheduling data structures shall be
565 * @param ready_set The ready set of the list scheduler.
566 * @param already_scheduled A set containing all nodes already
569 static void add_tuple_projs(block_sched_env_t *env, ir_node *irn)
571 const ir_edge_t *edge;
573 assert(get_irn_mode(irn) == mode_T && "Mode of node must be tuple");
575 foreach_out_edge(irn, edge) {
576 ir_node *out = edge->src;
578 assert(is_Proj(out) && "successor of a modeT node must be a proj");
580 if(get_irn_mode(out) == mode_T)
581 add_tuple_projs(env, out);
583 add_to_sched(env, out);
584 make_users_ready(env, out);
589 static ir_node *select_node(block_sched_env_t *be)
593 for (irn = nodeset_first(be->ready_set); irn; irn = nodeset_next(be->ready_set)) {
594 if (be_is_Keep(irn)) {
595 nodeset_break(be->ready_set);
600 return be->selector->select(be->selector_block_env, be->ready_set);
604 * Perform list scheduling on a block.
606 * Note, that the caller must compute a linked list of nodes in the block
607 * using the link field before calling this function.
609 * Also the outs must have been computed.
611 * @param block The block node.
612 * @param env Scheduling environment.
614 static void list_sched_block(ir_node *block, void *env_ptr)
616 sched_env_t *env = env_ptr;
617 const list_sched_selector_t *selector = env->selector;
618 ir_node *start_node = get_irg_start(get_irn_irg(block));
620 sched_info_t *info = get_irn_sched_info(block);
622 block_sched_env_t be;
623 const ir_edge_t *edge;
627 /* Initialize the block's list head that will hold the schedule. */
628 INIT_LIST_HEAD(&info->list);
630 /* Initialize the block scheduling environment */
633 be.ready_set = new_nodeset(get_irn_n_edges(block));
634 be.already_scheduled = new_nodeset(get_irn_n_edges(block));
635 be.selector = selector;
636 FIRM_DBG_REGISTER(be.dbg, "firm.be.sched");
638 if(selector->init_block)
639 be.selector_block_env = selector->init_block(env->selector_env, block);
641 DBG((be.dbg, LEVEL_1, "scheduling %+F\n", block));
643 /* Then one can add all nodes are ready to the set. */
644 foreach_out_edge(block, edge) {
645 ir_node *irn = get_edge_src_irn(edge);
647 /* Skip the end node because of keepalive edges. */
648 if(get_irn_opcode(irn) == iro_End)
651 /* Phi functions are scheduled immediately, since they only transfer
652 * data flow from the predecessors to this block. */
654 add_to_sched(&be, irn);
655 make_users_ready(&be, irn);
659 /* The start block will be scheduled as the first node */
660 else if(irn == start_node) {
661 add_to_sched(&be, irn);
662 add_tuple_projs(&be, irn);
666 /* Other nodes must have all operands in other blocks to be made
671 /* Check, if the operands of a node are not local to this block */
672 for(j = 0, m = get_irn_arity(irn); j < m; ++j) {
673 ir_node *operand = get_irn_n(irn, j);
675 if(get_nodes_block(operand) == block) {
681 /* Make the node ready, if all operands live in a foreign block */
683 DBG((be.dbg, LEVEL_2, "\timmediately ready: %+F\n", irn));
684 make_ready(&be, irn);
689 /* Increase the time, if some phi functions have been scheduled */
690 be.curr_time += phi_seen;
692 while (nodeset_count(be.ready_set) > 0) {
693 /* collect statitics about amount of ready nodes */
694 be_do_stat_sched_ready(block, be.ready_set);
696 /* select a node to be scheduled and check if it was ready */
697 irn = select_node(&be);
699 DBG((be.dbg, LEVEL_3, "\tpicked node %+F\n", irn));
701 /* Add the node to the schedule. */
702 add_to_sched(&be, irn);
704 if(get_irn_mode(irn) == mode_T)
705 add_tuple_projs(&be, irn);
707 make_users_ready(&be, irn);
709 /* Increase the time step. */
712 /* remove the scheduled node from the ready list. */
713 if (nodeset_find(be.ready_set, irn))
714 nodeset_remove(be.ready_set, irn);
717 if(selector->finish_block)
718 selector->finish_block(be.selector_block_env);
720 del_nodeset(be.ready_set);
721 del_nodeset(be.already_scheduled);