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 ir_graph *irg; /**< The graph to schedule. */
45 const list_sched_selector_t *selector; /**< The node selector. */
46 void *selector_env; /**< A pointer to give to the selector. */
51 * Ugly global variable for the compare function
52 * since qsort(3) does not pass an extra pointer.
54 static ir_node *curr_bl = NULL;
56 static int cmp_usage(const void *a, const void *b)
58 struct trivial_sched_env *env;
63 res = is_live_end(env->curr_bl, a) - is_live_end(env->curr_bl, b);
66 * One of them is live at the end of the block.
67 * Then, that one shall be scheduled at after the other
77 static ir_node *trivial_select(void *block_env, pset *ready_set)
81 res = pset_first(ready_set);
82 pset_break(ready_set);
86 static INLINE int must_appear_in_schedule(const list_sched_selector_t *sel, void *block_env, const ir_node *irn)
90 if(sel->to_appear_in_schedule)
91 res = sel->to_appear_in_schedule(block_env, irn);
93 return res || to_appear_in_schedule(irn) || be_is_Keep(irn);
96 static const list_sched_selector_t trivial_selector_struct = {
105 const list_sched_selector_t *trivial_selector = &trivial_selector_struct;
107 typedef struct _usage_stats_t {
109 struct _usage_stats_t *next;
111 int uses_in_block; /**< Number of uses inside the current block. */
112 int already_consumed; /**< Number of insns using this value already
119 pset *already_scheduled;
120 const list_sched_selector_t *vtab;
121 } reg_pressure_selector_env_t;
123 static INLINE usage_stats_t *get_or_set_usage_stats(reg_pressure_selector_env_t *env, ir_node *irn)
125 usage_stats_t *us = get_irn_link(irn);
128 us = obstack_alloc(&env->obst, sizeof(us[0]));
130 us->already_consumed = 0;
131 us->max_hops = INT_MAX;
132 us->next = env->root;
134 set_irn_link(irn, us);
140 static INLINE usage_stats_t *get_usage_stats(ir_node *irn)
142 usage_stats_t *us = get_irn_link(irn);
143 assert(us && "This node must have usage stats");
147 static int max_hops_walker(reg_pressure_selector_env_t *env, ir_node *irn, ir_node *curr_bl, int depth, unsigned visited_nr)
149 ir_node *bl = get_nodes_block(irn);
151 * If the reached node is not in the block desired,
152 * return the value passed for this situation.
154 if(get_nodes_block(irn) != bl)
155 return block_dominates(bl, curr_bl) ? 0 : INT_MAX;
158 * If the node is in the current block but not
159 * yet scheduled, we keep on searching from that node.
161 if(!pset_find_ptr(env->already_scheduled, irn)) {
164 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
165 ir_node *operand = get_irn_n(irn, i);
167 if(get_irn_visited(operand) < visited_nr) {
170 set_irn_visited(operand, visited_nr);
171 tmp = max_hops_walker(env, operand, bl, depth + 1, visited_nr);
180 * If the node is in the current block and scheduled, return
181 * the depth which indicates the number of steps to the
182 * region of scheduled nodes.
187 static int compute_max_hops(reg_pressure_selector_env_t *env, ir_node *irn)
189 ir_node *bl = get_nodes_block(irn);
190 ir_graph *irg = get_irn_irg(bl);
193 const ir_edge_t *edge;
195 foreach_out_edge(irn, edge) {
196 ir_node *user = get_edge_src_irn(edge);
197 unsigned visited_nr = get_irg_visited(irg) + 1;
200 set_irg_visited(irg, visited_nr);
201 max_hops = max_hops_walker(env, user, irn, 0, visited_nr);
202 res = MAX(res, max_hops);
208 static void *reg_pressure_graph_init(const list_sched_selector_t *vtab, const arch_isa_t *isa, ir_graph *irg)
210 irg_walk_graph(irg, firm_clear_link, NULL, NULL);
211 return (void *) vtab;
214 static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
217 reg_pressure_selector_env_t *env = xmalloc(sizeof(env[0]));
219 obstack_init(&env->obst);
220 env->already_scheduled = pset_new_ptr(32);
222 env->vtab = graph_env;
225 * Collect usage statistics.
227 sched_foreach(bl, irn) {
228 if(must_appear_in_schedule(env->vtab, env, irn)) {
231 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
232 ir_node *op = get_irn_n(irn, i);
233 if(must_appear_in_schedule(env->vtab, env, irn)) {
234 usage_stats_t *us = get_or_set_usage_stats(env, irn);
235 if(is_live_end(bl, op))
236 us->uses_in_block = 99999;
247 static void reg_pressure_block_free(void *block_env)
249 reg_pressure_selector_env_t *env = block_env;
252 for(us = env->root; us; us = us->next)
253 set_irn_link(us->irn, NULL);
255 obstack_free(&env->obst, NULL);
256 del_pset(env->already_scheduled);
260 static int get_result_hops_sum(reg_pressure_selector_env_t *env, ir_node *irn)
263 if(get_irn_mode(irn) == mode_T) {
264 const ir_edge_t *edge;
266 foreach_out_edge(irn, edge)
267 res += get_result_hops_sum(env, get_edge_src_irn(edge));
270 else if(mode_is_data(get_irn_mode(irn)))
271 res = compute_max_hops(env, irn);
277 static INLINE int reg_pr_costs(reg_pressure_selector_env_t *env, ir_node *irn)
282 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
283 ir_node *op = get_irn_n(irn, i);
285 if(must_appear_in_schedule(env->vtab, env, op))
286 sum += compute_max_hops(env, op);
289 sum += get_result_hops_sum(env, irn);
294 static ir_node *reg_pressure_select(void *block_env, pset *ready_set)
296 reg_pressure_selector_env_t *env = block_env;
297 ir_node *irn, *res = NULL;
298 int curr_cost = INT_MAX;
300 assert(pset_count(ready_set) > 0);
302 for(irn = pset_first(ready_set); irn; irn = pset_next(ready_set)) {
303 int costs = reg_pr_costs(env, irn);
304 if(costs <= curr_cost) {
310 pset_insert_ptr(env->already_scheduled, res);
314 static const list_sched_selector_t reg_pressure_selector_struct = {
315 reg_pressure_graph_init,
316 reg_pressure_block_init,
319 reg_pressure_block_free,
323 const list_sched_selector_t *reg_pressure_selector = ®_pressure_selector_struct;
325 static void list_sched_block(ir_node *block, void *env_ptr);
327 void list_sched(const struct _arch_isa_t *isa, ir_graph *irg)
330 const list_sched_selector_t *selector;
332 memset(&env, 0, sizeof(env));
333 selector = env.selector = isa->impl->get_list_sched_selector(isa);
334 env.selector_env = selector->init_graph ? selector->init_graph(selector, isa, irg) : NULL;
337 /* Assure, that the out edges are computed */
340 /* Schedule each single block. */
341 irg_block_walk_graph(irg, list_sched_block, NULL, &env);
343 if(selector->finish_graph)
344 selector->finish_graph(env.selector_env);
349 * Environment for a block scheduler.
351 typedef struct _block_sched_env_t {
354 pset *already_scheduled;
356 firm_dbg_module_t *dbg;
357 const list_sched_selector_t *selector;
358 void *selector_block_env;
362 * Try to put a node in the ready set.
363 * @param env The block scheduler environment.
364 * @param irn The node to make ready.
365 * @return 1, if the node could be made ready, 0 else.
367 static INLINE int make_ready(block_sched_env_t *env, ir_node *irn)
371 /* Blocks cannot be scheduled. */
376 * Check, if the given ir node is in a different block as the
377 * currently scheduled one. If that is so, don't make the node ready.
379 if(env->block != get_nodes_block(irn))
382 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
383 ir_node *op = get_irn_n(irn, i);
385 /* If the operand is local to the scheduled block and not yet
386 * scheduled, this nodes cannot be made ready, so exit. */
387 if(!pset_find_ptr(env->already_scheduled, op) && get_nodes_block(op) == env->block)
391 DBG((env->dbg, LEVEL_2, "\tmaking ready: %+F\n", irn));
392 pset_insert_ptr(env->ready_set, irn);
398 * Check, if a node is ready in a block schedule.
399 * @param env The block schedule environment.
400 * @param irn The node to check for.
401 * @return 1 if the node was ready, 0 if not.
403 #define is_ready(env,irn) \
404 (pset_find_ptr((env)->ready_set, irn) != NULL)
407 * Check, if a node has already been schedules.
408 * @param env The block schedule environment.
409 * @param irn The node to check for.
410 * @return 1 if the node was already scheduled, 0 if not.
412 #define is_scheduled(env,irn) \
413 (pset_find_ptr((env)->already_scheduled, irn) != NULL)
416 * Try, to make all users of a node ready.
417 * In fact, a usage node can only be made ready, if all its operands
418 * have already been scheduled yet. This is checked my make_ready().
419 * @param env The block schedule environment.
420 * @param irn The node, which usages (successors) are to be made ready.
422 static INLINE void make_users_ready(block_sched_env_t *env, ir_node *irn)
424 const ir_edge_t *edge;
426 foreach_out_edge(irn, edge) {
427 ir_node *user = edge->src;
429 make_ready(env, user);
434 * Compare to nodes using pointer equality.
435 * @param p1 Node one.
436 * @param p2 Node two.
437 * @return 0 if they are identical.
439 static int node_cmp_func(const void *p1, const void *p2)
445 * Append an instruction to a schedule.
446 * @param env The block scheduling environment.
447 * @param irn The node to add to the schedule.
448 * @return The given node.
450 static ir_node *add_to_sched(block_sched_env_t *env, ir_node *irn)
452 /* If the node consumes/produces data, it is appended to the schedule
453 * list, otherwise, it is not put into the list */
454 if(must_appear_in_schedule(env->selector, env->selector_block_env, irn)) {
455 sched_info_t *info = get_irn_sched_info(irn);
456 INIT_LIST_HEAD(&info->list);
458 sched_add_before(env->block, irn);
460 DBG((env->dbg, LEVEL_2, "\tadding %+F\n", irn));
463 /* Insert the node in the set of all already scheduled nodes. */
464 pset_insert_ptr(env->already_scheduled, irn);
466 /* Remove the node from the ready set */
467 if(pset_find_ptr(env->ready_set, irn))
468 pset_remove_ptr(env->ready_set, irn);
474 * Add the proj nodes of a tuple-mode irn to the schedule immediately
475 * after the tuple-moded irn. By pinning the projs after the irn, no
476 * other nodes can create a new lifetime between the tuple-moded irn and
477 * one of its projs. This should render a realistic image of a
478 * tuple-moded irn, which in fact models a node which defines multiple
481 * @param irn The tuple-moded irn.
482 * @param list The schedule list to append all the projs.
483 * @param time The time step to which the irn and all its projs are
485 * @param obst The obstack the scheduling data structures shall be
487 * @param ready_set The ready set of the list scheduler.
488 * @param already_scheduled A set containing all nodes already
491 static void add_tuple_projs(block_sched_env_t *env, ir_node *irn)
493 const ir_edge_t *edge;
495 assert(get_irn_mode(irn) == mode_T && "Mode of node must be tuple");
497 foreach_out_edge(irn, edge) {
498 ir_node *out = edge->src;
500 assert(is_Proj(out) && "successor of a modeT node must be a proj");
502 if(get_irn_mode(out) == mode_T)
503 add_tuple_projs(env, out);
505 add_to_sched(env, out);
506 make_users_ready(env, out);
511 static ir_node *select_node(block_sched_env_t *be)
515 for(irn = pset_first(be->ready_set); irn; irn = pset_next(be->ready_set)) {
516 if(be_is_Keep(irn)) {
517 pset_break(be->ready_set);
522 return be->selector->select(be->selector_block_env, be->ready_set);
526 * Perform list scheduling on a block.
528 * Note, that the caller must compute a linked list of nodes in the block
529 * using the link field before calling this function.
531 * Also the outs must have been computed.
533 * @param block The block node.
534 * @param env Scheduling environment.
536 static void list_sched_block(ir_node *block, void *env_ptr)
538 sched_env_t *env = env_ptr;
539 block_sched_env_t be;
540 const list_sched_selector_t *selector = env->selector;
541 const ir_edge_t *edge;
543 ir_node *start_node = get_irg_start(get_irn_irg(block));
544 ir_node *final_jmp = NULL;
547 sched_info_t *info = get_irn_sched_info(block);
549 /* Initialize the block's list head that will hold the schedule. */
550 INIT_LIST_HEAD(&info->list);
552 /* Initialize the block scheduling environment */
553 be.dbg = firm_dbg_register("firm.be.sched");
556 be.ready_set = new_pset(node_cmp_func, get_irn_n_edges(block));
557 be.already_scheduled = new_pset(node_cmp_func, get_irn_n_edges(block));
558 be.selector = selector;
560 if(selector->init_block)
561 be.selector_block_env = selector->init_block(env->selector_env, block);
563 DBG((be.dbg, LEVEL_1, "scheduling %+F\n", block));
565 /* Then one can add all nodes are ready to the set. */
566 foreach_out_edge(block, edge) {
567 ir_node *irn = get_edge_src_irn(edge);
569 /* Skip the end node because of keepalive edges. */
570 if(get_irn_opcode(irn) == iro_End)
573 /* Phi functions are scheduled immediately, since they only transfer
574 * data flow from the predecessors to this block. */
576 add_to_sched(&be, irn);
577 make_users_ready(&be, irn);
581 else if(irn == start_node) {
582 add_to_sched(&be, irn);
583 add_tuple_projs(&be, irn);
586 else if(get_irn_opcode(irn) == iro_Jmp) {
590 /* Other nodes must have all operands in other blocks to be made
595 /* Check, if the operands of a node are not local to this block */
596 for(j = 0, m = get_irn_arity(irn); j < m; ++j) {
597 ir_node *operand = get_irn_n(irn, j);
599 if(get_nodes_block(operand) == block) {
605 /* Make the node ready, if all operands live in a foreign block */
607 DBG((be.dbg, LEVEL_2, "\timmediately ready: %+F\n", irn));
608 make_ready(&be, irn);
613 /* Increase the time, if some phi functions have been scheduled */
614 be.curr_time += phi_seen;
616 while(pset_count(be.ready_set) > 0) {
617 /* select a node to be scheduled and check if it was ready */
618 irn = select_node(&be);
620 DBG((be.dbg, LEVEL_3, "\tpicked node %+F\n", irn));
622 /* Add the node to the schedule. */
623 add_to_sched(&be, irn);
625 if(get_irn_mode(irn) == mode_T)
626 add_tuple_projs(&be, irn);
628 make_users_ready(&be, irn);
630 /* Increase the time step. */
633 /* remove the scheduled node from the ready list. */
634 if(pset_find_ptr(be.ready_set, irn))
635 pset_remove_ptr(be.ready_set, irn);
638 if(selector->finish_block)
639 selector->finish_block(be.selector_block_env);
642 add_to_sched(&be, final_jmp);
644 del_pset(be.ready_set);
645 del_pset(be.already_scheduled);