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"
37 #define MAX(x,y) ((x) > (y) ? (x) : (y))
38 #define MIN(x,y) ((x) < (y) ? (x) : (y))
41 * Scheduling environment for the whole graph.
43 typedef struct _sched_env_t {
44 const list_sched_selector_t *selector; /**< The node selector. */
45 const arch_env_t *arch_env; /**< The architecture enviromnent. */
46 const ir_graph *irg; /**< The graph to schedule. */
47 void *selector_env; /**< A pointer to give to the selector. */
52 * Ugly global variable for the compare function
53 * since qsort(3) does not pass an extra pointer.
55 static ir_node *curr_bl = NULL;
57 static int cmp_usage(const void *a, const void *b)
59 struct trivial_sched_env *env;
64 res = is_live_end(env->curr_bl, a) - is_live_end(env->curr_bl, b);
67 * One of them is live at the end of the block.
68 * Then, that one shall be scheduled at after the other
78 static ir_node *trivial_select(void *block_env, pset *ready_set)
80 const arch_env_t *arch_env = block_env;
83 for(irn = pset_first(ready_set); irn; irn = pset_next(ready_set)) {
84 if(arch_irn_classify(arch_env, irn) != arch_irn_class_branch) {
85 pset_break(ready_set);
90 irn = pset_first(ready_set);
91 pset_break(ready_set);
96 static void *trivial_init_graph(const list_sched_selector_t *vtab, const arch_env_t *arch_env, ir_graph *irg)
98 return (void *) arch_env;
101 static void *trivial_init_block(void *graph_env, ir_node *bl)
106 static INLINE int must_appear_in_schedule(const list_sched_selector_t *sel, void *block_env, const ir_node *irn)
110 if(sel->to_appear_in_schedule)
111 res = sel->to_appear_in_schedule(block_env, irn);
113 return res || to_appear_in_schedule(irn) || be_is_Keep(irn) || be_is_RegParams(irn);
116 static const list_sched_selector_t trivial_selector_struct = {
125 const list_sched_selector_t *trivial_selector = &trivial_selector_struct;
127 typedef struct _usage_stats_t {
129 struct _usage_stats_t *next;
131 int uses_in_block; /**< Number of uses inside the current block. */
132 int already_consumed; /**< Number of insns using this value already
137 const list_sched_selector_t *vtab;
138 const arch_env_t *arch_env;
139 } reg_pressure_main_env_t;
143 const reg_pressure_main_env_t *main_env;
145 pset *already_scheduled;
146 } reg_pressure_selector_env_t;
148 static INLINE usage_stats_t *get_or_set_usage_stats(reg_pressure_selector_env_t *env, ir_node *irn)
150 usage_stats_t *us = get_irn_link(irn);
153 us = obstack_alloc(&env->obst, sizeof(us[0]));
155 us->already_consumed = 0;
156 us->max_hops = INT_MAX;
157 us->next = env->root;
159 set_irn_link(irn, us);
165 static INLINE usage_stats_t *get_usage_stats(ir_node *irn)
167 usage_stats_t *us = get_irn_link(irn);
168 assert(us && "This node must have usage stats");
172 static int max_hops_walker(reg_pressure_selector_env_t *env, ir_node *irn, ir_node *curr_bl, int depth, unsigned visited_nr)
174 ir_node *bl = get_nodes_block(irn);
176 * If the reached node is not in the block desired,
177 * return the value passed for this situation.
179 if(get_nodes_block(irn) != bl)
180 return block_dominates(bl, curr_bl) ? 0 : INT_MAX;
183 * If the node is in the current block but not
184 * yet scheduled, we keep on searching from that node.
186 if(!pset_find_ptr(env->already_scheduled, irn)) {
189 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
190 ir_node *operand = get_irn_n(irn, i);
192 if(get_irn_visited(operand) < visited_nr) {
195 set_irn_visited(operand, visited_nr);
196 tmp = max_hops_walker(env, operand, bl, depth + 1, visited_nr);
205 * If the node is in the current block and scheduled, return
206 * the depth which indicates the number of steps to the
207 * region of scheduled nodes.
212 static int compute_max_hops(reg_pressure_selector_env_t *env, ir_node *irn)
214 ir_node *bl = get_nodes_block(irn);
215 ir_graph *irg = get_irn_irg(bl);
218 const ir_edge_t *edge;
220 foreach_out_edge(irn, edge) {
221 ir_node *user = get_edge_src_irn(edge);
222 unsigned visited_nr = get_irg_visited(irg) + 1;
225 set_irg_visited(irg, visited_nr);
226 max_hops = max_hops_walker(env, user, irn, 0, visited_nr);
227 res = MAX(res, max_hops);
233 static void *reg_pressure_graph_init(const list_sched_selector_t *vtab, const arch_env_t *arch_env, ir_graph *irg)
235 reg_pressure_main_env_t *main_env = xmalloc(sizeof(main_env[0]));
237 main_env->arch_env = arch_env;
238 main_env->vtab = vtab;
239 irg_walk_graph(irg, firm_clear_link, NULL, NULL);
244 static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
247 reg_pressure_selector_env_t *env = xmalloc(sizeof(env[0]));
249 obstack_init(&env->obst);
250 env->already_scheduled = pset_new_ptr(32);
252 env->main_env = graph_env;
255 * Collect usage statistics.
257 sched_foreach(bl, irn) {
258 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
261 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
262 ir_node *op = get_irn_n(irn, i);
263 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
264 usage_stats_t *us = get_or_set_usage_stats(env, irn);
265 if(is_live_end(bl, op))
266 us->uses_in_block = 99999;
277 static void reg_pressure_block_free(void *block_env)
279 reg_pressure_selector_env_t *env = block_env;
282 for(us = env->root; us; us = us->next)
283 set_irn_link(us->irn, NULL);
285 obstack_free(&env->obst, NULL);
286 del_pset(env->already_scheduled);
290 static int get_result_hops_sum(reg_pressure_selector_env_t *env, ir_node *irn)
293 if(get_irn_mode(irn) == mode_T) {
294 const ir_edge_t *edge;
296 foreach_out_edge(irn, edge)
297 res += get_result_hops_sum(env, get_edge_src_irn(edge));
300 else if(mode_is_data(get_irn_mode(irn)))
301 res = compute_max_hops(env, irn);
307 static INLINE int reg_pr_costs(reg_pressure_selector_env_t *env, ir_node *irn)
312 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
313 ir_node *op = get_irn_n(irn, i);
315 if(must_appear_in_schedule(env->main_env->vtab, env, op))
316 sum += compute_max_hops(env, op);
319 sum += get_result_hops_sum(env, irn);
324 static ir_node *reg_pressure_select(void *block_env, pset *ready_set)
326 reg_pressure_selector_env_t *env = block_env;
327 ir_node *irn, *res = NULL;
328 int curr_cost = INT_MAX;
330 assert(pset_count(ready_set) > 0);
332 for(irn = pset_first(ready_set); irn; irn = pset_next(ready_set)) {
334 Ignore branch instructions for the time being.
335 They should only be scheduled if there is nothing else.
337 if(arch_irn_classify(env->main_env->arch_env, irn) != arch_irn_class_branch) {
338 int costs = reg_pr_costs(env, irn);
339 if(costs <= curr_cost) {
347 There was no result so we only saw a branch.
352 res = pset_first(ready_set);
353 pset_break(ready_set);
355 assert(res && "There must be a node scheduled.");
358 pset_insert_ptr(env->already_scheduled, res);
362 static const list_sched_selector_t reg_pressure_selector_struct = {
363 reg_pressure_graph_init,
364 reg_pressure_block_init,
367 reg_pressure_block_free,
371 const list_sched_selector_t *reg_pressure_selector = ®_pressure_selector_struct;
373 static void list_sched_block(ir_node *block, void *env_ptr);
375 void list_sched(const arch_env_t *arch_env, ir_graph *irg)
379 memset(&env, 0, sizeof(env));
380 env.selector = arch_env->isa->impl->get_list_sched_selector(arch_env->isa);
381 env.arch_env = arch_env;
384 if(env.selector->init_graph)
385 env.selector_env = env.selector->init_graph(env.selector, arch_env, irg);
387 /* Assure, that the out edges are computed */
390 /* Schedule each single block. */
391 irg_block_walk_graph(irg, list_sched_block, NULL, &env);
393 if(env.selector->finish_graph)
394 env.selector->finish_graph(env.selector_env);
399 * Environment for a block scheduler.
401 typedef struct _block_sched_env_t {
404 pset *already_scheduled;
406 firm_dbg_module_t *dbg;
407 const list_sched_selector_t *selector;
408 void *selector_block_env;
412 * Try to put a node in the ready set.
413 * @param env The block scheduler environment.
414 * @param irn The node to make ready.
415 * @return 1, if the node could be made ready, 0 else.
417 static INLINE int make_ready(block_sched_env_t *env, ir_node *irn)
421 /* Blocks cannot be scheduled. */
426 * Check, if the given ir node is in a different block as the
427 * currently scheduled one. If that is so, don't make the node ready.
429 if(env->block != get_nodes_block(irn))
432 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
433 ir_node *op = get_irn_n(irn, i);
435 /* If the operand is local to the scheduled block and not yet
436 * scheduled, this nodes cannot be made ready, so exit. */
437 if(!pset_find_ptr(env->already_scheduled, op) && get_nodes_block(op) == env->block)
441 DBG((env->dbg, LEVEL_2, "\tmaking ready: %+F\n", irn));
442 pset_insert_ptr(env->ready_set, irn);
448 * Check, if a node is ready in a block schedule.
449 * @param env The block schedule environment.
450 * @param irn The node to check for.
451 * @return 1 if the node was ready, 0 if not.
453 #define is_ready(env,irn) \
454 (pset_find_ptr((env)->ready_set, irn) != NULL)
457 * Check, if a node has already been schedules.
458 * @param env The block schedule environment.
459 * @param irn The node to check for.
460 * @return 1 if the node was already scheduled, 0 if not.
462 #define is_scheduled(env,irn) \
463 (pset_find_ptr((env)->already_scheduled, irn) != NULL)
466 * Try, to make all users of a node ready.
467 * In fact, a usage node can only be made ready, if all its operands
468 * have already been scheduled yet. This is checked my make_ready().
469 * @param env The block schedule environment.
470 * @param irn The node, which usages (successors) are to be made ready.
472 static INLINE void make_users_ready(block_sched_env_t *env, ir_node *irn)
474 const ir_edge_t *edge;
476 foreach_out_edge(irn, edge) {
477 ir_node *user = edge->src;
479 make_ready(env, user);
484 * Compare to nodes using pointer equality.
485 * @param p1 Node one.
486 * @param p2 Node two.
487 * @return 0 if they are identical.
489 static int node_cmp_func(const void *p1, const void *p2)
495 * Append an instruction to a schedule.
496 * @param env The block scheduling environment.
497 * @param irn The node to add to the schedule.
498 * @return The given node.
500 static ir_node *add_to_sched(block_sched_env_t *env, ir_node *irn)
502 /* If the node consumes/produces data, it is appended to the schedule
503 * list, otherwise, it is not put into the list */
504 if(must_appear_in_schedule(env->selector, env->selector_block_env, irn)) {
505 sched_info_t *info = get_irn_sched_info(irn);
506 INIT_LIST_HEAD(&info->list);
508 sched_add_before(env->block, irn);
510 DBG((env->dbg, LEVEL_2, "\tadding %+F\n", irn));
513 /* Insert the node in the set of all already scheduled nodes. */
514 pset_insert_ptr(env->already_scheduled, irn);
516 /* Remove the node from the ready set */
517 if(pset_find_ptr(env->ready_set, irn))
518 pset_remove_ptr(env->ready_set, irn);
524 * Add the proj nodes of a tuple-mode irn to the schedule immediately
525 * after the tuple-moded irn. By pinning the projs after the irn, no
526 * other nodes can create a new lifetime between the tuple-moded irn and
527 * one of its projs. This should render a realistic image of a
528 * tuple-moded irn, which in fact models a node which defines multiple
531 * @param irn The tuple-moded irn.
532 * @param list The schedule list to append all the projs.
533 * @param time The time step to which the irn and all its projs are
535 * @param obst The obstack the scheduling data structures shall be
537 * @param ready_set The ready set of the list scheduler.
538 * @param already_scheduled A set containing all nodes already
541 static void add_tuple_projs(block_sched_env_t *env, ir_node *irn)
543 const ir_edge_t *edge;
545 assert(get_irn_mode(irn) == mode_T && "Mode of node must be tuple");
547 foreach_out_edge(irn, edge) {
548 ir_node *out = edge->src;
550 assert(is_Proj(out) && "successor of a modeT node must be a proj");
552 if(get_irn_mode(out) == mode_T)
553 add_tuple_projs(env, out);
555 add_to_sched(env, out);
556 make_users_ready(env, out);
561 static ir_node *select_node(block_sched_env_t *be)
565 for(irn = pset_first(be->ready_set); irn; irn = pset_next(be->ready_set)) {
566 if(be_is_Keep(irn)) {
567 pset_break(be->ready_set);
572 return be->selector->select(be->selector_block_env, be->ready_set);
576 * Perform list scheduling on a block.
578 * Note, that the caller must compute a linked list of nodes in the block
579 * using the link field before calling this function.
581 * Also the outs must have been computed.
583 * @param block The block node.
584 * @param env Scheduling environment.
586 static void list_sched_block(ir_node *block, void *env_ptr)
588 sched_env_t *env = env_ptr;
589 const list_sched_selector_t *selector = env->selector;
590 ir_node *start_node = get_irg_start(get_irn_irg(block));
592 sched_info_t *info = get_irn_sched_info(block);
594 block_sched_env_t be;
595 const ir_edge_t *edge;
599 /* Initialize the block's list head that will hold the schedule. */
600 INIT_LIST_HEAD(&info->list);
602 /* Initialize the block scheduling environment */
603 be.dbg = firm_dbg_register("firm.be.sched");
606 be.ready_set = new_pset(node_cmp_func, get_irn_n_edges(block));
607 be.already_scheduled = new_pset(node_cmp_func, get_irn_n_edges(block));
608 be.selector = selector;
610 if(selector->init_block)
611 be.selector_block_env = selector->init_block(env->selector_env, block);
613 DBG((be.dbg, LEVEL_1, "scheduling %+F\n", block));
615 /* Then one can add all nodes are ready to the set. */
616 foreach_out_edge(block, edge) {
617 ir_node *irn = get_edge_src_irn(edge);
619 /* Skip the end node because of keepalive edges. */
620 if(get_irn_opcode(irn) == iro_End)
623 /* Phi functions are scheduled immediately, since they only transfer
624 * data flow from the predecessors to this block. */
626 add_to_sched(&be, irn);
627 make_users_ready(&be, irn);
631 /* The start block will be scheduled as the first node */
632 else if(irn == start_node) {
633 add_to_sched(&be, irn);
634 add_tuple_projs(&be, irn);
638 /* Other nodes must have all operands in other blocks to be made
643 /* Check, if the operands of a node are not local to this block */
644 for(j = 0, m = get_irn_arity(irn); j < m; ++j) {
645 ir_node *operand = get_irn_n(irn, j);
647 if(get_nodes_block(operand) == block) {
653 /* Make the node ready, if all operands live in a foreign block */
655 DBG((be.dbg, LEVEL_2, "\timmediately ready: %+F\n", irn));
656 make_ready(&be, irn);
661 /* Increase the time, if some phi functions have been scheduled */
662 be.curr_time += phi_seen;
664 while(pset_count(be.ready_set) > 0) {
665 /* select a node to be scheduled and check if it was ready */
666 irn = select_node(&be);
668 DBG((be.dbg, LEVEL_3, "\tpicked node %+F\n", irn));
670 /* Add the node to the schedule. */
671 add_to_sched(&be, irn);
673 if(get_irn_mode(irn) == mode_T)
674 add_tuple_projs(&be, irn);
676 make_users_ready(&be, irn);
678 /* Increase the time step. */
681 /* remove the scheduled node from the ready list. */
682 if(pset_find_ptr(be.ready_set, irn))
683 pset_remove_ptr(be.ready_set, irn);
686 if(selector->finish_block)
687 selector->finish_block(be.selector_block_env);
689 del_pset(be.ready_set);
690 del_pset(be.already_scheduled);