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
79 * The trivial selector:
80 * Just assure that branches are executed last, otherwise select
81 * the first node ready.
83 static ir_node *trivial_select(void *block_env, nodeset *ready_set)
85 const arch_env_t *arch_env = block_env;
89 /* assure that branches and constants are executed last */
90 for (irn = nodeset_first(ready_set); irn; irn = nodeset_next(ready_set)) {
91 arch_irn_class_t irn_class = arch_irn_classify(arch_env, irn);
93 if (irn_class != arch_irn_class_branch && (const_last ? (irn_class != arch_irn_class_const) : 1)) {
94 nodeset_break(ready_set);
99 /* assure that constants are executed before branches */
101 for (irn = nodeset_first(ready_set); irn; irn = nodeset_next(ready_set)) {
102 if (arch_irn_classify(arch_env, irn) != arch_irn_class_branch) {
103 nodeset_break(ready_set);
110 /* at last: schedule branches */
111 irn = nodeset_first(ready_set);
112 nodeset_break(ready_set);
117 static void *trivial_init_graph(const list_sched_selector_t *vtab, const arch_env_t *arch_env, ir_graph *irg)
119 return (void *) arch_env;
122 static void *trivial_init_block(void *graph_env, ir_node *bl)
127 static INLINE int must_appear_in_schedule(const list_sched_selector_t *sel, void *block_env, const ir_node *irn)
131 if(sel->to_appear_in_schedule)
132 res = sel->to_appear_in_schedule(block_env, irn);
134 return res || to_appear_in_schedule(irn) || be_is_Keep(irn) || be_is_RegParams(irn);
137 static const list_sched_selector_t trivial_selector_struct = {
146 const list_sched_selector_t *trivial_selector = &trivial_selector_struct;
148 typedef struct _usage_stats_t {
150 struct _usage_stats_t *next;
152 int uses_in_block; /**< Number of uses inside the current block. */
153 int already_consumed; /**< Number of insns using this value already
158 const list_sched_selector_t *vtab;
159 const arch_env_t *arch_env;
160 } reg_pressure_main_env_t;
164 const reg_pressure_main_env_t *main_env;
166 nodeset *already_scheduled;
167 } reg_pressure_selector_env_t;
169 static INLINE usage_stats_t *get_or_set_usage_stats(reg_pressure_selector_env_t *env, ir_node *irn)
171 usage_stats_t *us = get_irn_link(irn);
174 us = obstack_alloc(&env->obst, sizeof(us[0]));
176 us->already_consumed = 0;
177 us->max_hops = INT_MAX;
178 us->next = env->root;
180 set_irn_link(irn, us);
186 static INLINE usage_stats_t *get_usage_stats(ir_node *irn)
188 usage_stats_t *us = get_irn_link(irn);
189 assert(us && "This node must have usage stats");
193 static int max_hops_walker(reg_pressure_selector_env_t *env, ir_node *irn, ir_node *curr_bl, int depth, unsigned visited_nr)
195 ir_node *bl = get_nodes_block(irn);
197 * If the reached node is not in the block desired,
198 * return the value passed for this situation.
200 if(get_nodes_block(irn) != bl)
201 return block_dominates(bl, curr_bl) ? 0 : INT_MAX;
204 * If the node is in the current block but not
205 * yet scheduled, we keep on searching from that node.
207 if(!nodeset_find(env->already_scheduled, irn)) {
210 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
211 ir_node *operand = get_irn_n(irn, i);
213 if(get_irn_visited(operand) < visited_nr) {
216 set_irn_visited(operand, visited_nr);
217 tmp = max_hops_walker(env, operand, bl, depth + 1, visited_nr);
226 * If the node is in the current block and scheduled, return
227 * the depth which indicates the number of steps to the
228 * region of scheduled nodes.
233 static int compute_max_hops(reg_pressure_selector_env_t *env, ir_node *irn)
235 ir_node *bl = get_nodes_block(irn);
236 ir_graph *irg = get_irn_irg(bl);
239 const ir_edge_t *edge;
241 foreach_out_edge(irn, edge) {
242 ir_node *user = get_edge_src_irn(edge);
243 unsigned visited_nr = get_irg_visited(irg) + 1;
246 set_irg_visited(irg, visited_nr);
247 max_hops = max_hops_walker(env, user, irn, 0, visited_nr);
248 res = MAX(res, max_hops);
254 static void *reg_pressure_graph_init(const list_sched_selector_t *vtab, const arch_env_t *arch_env, ir_graph *irg)
256 reg_pressure_main_env_t *main_env = xmalloc(sizeof(main_env[0]));
258 main_env->arch_env = arch_env;
259 main_env->vtab = vtab;
260 irg_walk_graph(irg, firm_clear_link, NULL, NULL);
265 static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
268 reg_pressure_selector_env_t *env = xmalloc(sizeof(env[0]));
270 obstack_init(&env->obst);
271 env->already_scheduled = new_nodeset(32);
273 env->main_env = graph_env;
276 * Collect usage statistics.
278 sched_foreach(bl, irn) {
279 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
282 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
283 ir_node *op = get_irn_n(irn, i);
284 if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
285 usage_stats_t *us = get_or_set_usage_stats(env, irn);
286 if(is_live_end(bl, op))
287 us->uses_in_block = 99999;
298 static void reg_pressure_block_free(void *block_env)
300 reg_pressure_selector_env_t *env = block_env;
303 for(us = env->root; us; us = us->next)
304 set_irn_link(us->irn, NULL);
306 obstack_free(&env->obst, NULL);
307 del_nodeset(env->already_scheduled);
311 static int get_result_hops_sum(reg_pressure_selector_env_t *env, ir_node *irn)
314 if(get_irn_mode(irn) == mode_T) {
315 const ir_edge_t *edge;
317 foreach_out_edge(irn, edge)
318 res += get_result_hops_sum(env, get_edge_src_irn(edge));
321 else if(mode_is_data(get_irn_mode(irn)))
322 res = compute_max_hops(env, irn);
328 static INLINE int reg_pr_costs(reg_pressure_selector_env_t *env, ir_node *irn)
333 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
334 ir_node *op = get_irn_n(irn, i);
336 if(must_appear_in_schedule(env->main_env->vtab, env, op))
337 sum += compute_max_hops(env, op);
340 sum += get_result_hops_sum(env, irn);
345 static ir_node *reg_pressure_select(void *block_env, nodeset *ready_set)
347 reg_pressure_selector_env_t *env = block_env;
348 ir_node *irn, *res = NULL;
349 int curr_cost = INT_MAX;
351 assert(nodeset_count(ready_set) > 0);
353 for (irn = nodeset_first(ready_set); irn; irn = nodeset_next(ready_set)) {
355 Ignore branch instructions for the time being.
356 They should only be scheduled if there is nothing else.
358 if (arch_irn_classify(env->main_env->arch_env, irn) != arch_irn_class_branch) {
359 int costs = reg_pr_costs(env, irn);
360 if (costs <= curr_cost) {
368 There was no result so we only saw a branch.
373 res = nodeset_first(ready_set);
374 nodeset_break(ready_set);
376 assert(res && "There must be a node scheduled.");
379 nodeset_insert(env->already_scheduled, res);
383 static const list_sched_selector_t reg_pressure_selector_struct = {
384 reg_pressure_graph_init,
385 reg_pressure_block_init,
388 reg_pressure_block_free,
392 const list_sched_selector_t *reg_pressure_selector = ®_pressure_selector_struct;
394 static void list_sched_block(ir_node *block, void *env_ptr);
396 void list_sched(const arch_env_t *arch_env, ir_graph *irg)
400 memset(&env, 0, sizeof(env));
401 env.selector = arch_env->isa->impl->get_list_sched_selector(arch_env->isa);
402 env.arch_env = arch_env;
405 if(env.selector->init_graph)
406 env.selector_env = env.selector->init_graph(env.selector, arch_env, irg);
408 /* Assure, that the out edges are computed */
411 /* Schedule each single block. */
412 irg_block_walk_graph(irg, list_sched_block, NULL, &env);
414 if(env.selector->finish_graph)
415 env.selector->finish_graph(env.selector_env);
420 * Environment for a block scheduler.
422 typedef struct _block_sched_env_t {
425 nodeset *already_scheduled;
427 const list_sched_selector_t *selector;
428 void *selector_block_env;
429 DEBUG_ONLY(firm_dbg_module_t *dbg;)
433 * Try to put a node in the ready set.
434 * @param env The block scheduler environment.
435 * @param irn The node to make ready.
436 * @return 1, if the node could be made ready, 0 else.
438 static INLINE int make_ready(block_sched_env_t *env, ir_node *irn)
442 /* Blocks cannot be scheduled. */
447 * Check, if the given ir node is in a different block as the
448 * currently scheduled one. If that is so, don't make the node ready.
450 if(env->block != get_nodes_block(irn))
453 for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
454 ir_node *op = get_irn_n(irn, i);
456 /* if irn is an End we have keep-alives and op might be a block, skip that */
458 assert(get_irn_op(irn) == op_End);
462 /* If the operand is local to the scheduled block and not yet
463 * scheduled, this nodes cannot be made ready, so exit. */
464 if(!nodeset_find(env->already_scheduled, op) && get_nodes_block(op) == env->block)
468 DBG((env->dbg, LEVEL_2, "\tmaking ready: %+F\n", irn));
469 nodeset_insert(env->ready_set, irn);
475 * Check, if a node is ready in a block schedule.
476 * @param env The block schedule environment.
477 * @param irn The node to check for.
478 * @return 1 if the node was ready, 0 if not.
480 #define is_ready(env,irn) \
481 (nodeset_find((env)->ready_set, irn) != NULL)
484 * Check, if a node has already been schedules.
485 * @param env The block schedule environment.
486 * @param irn The node to check for.
487 * @return 1 if the node was already scheduled, 0 if not.
489 #define is_scheduled(env,irn) \
490 (nodeset_find((env)->already_scheduled, irn) != NULL)
493 * Try, to make all users of a node ready.
494 * In fact, a usage node can only be made ready, if all its operands
495 * have already been scheduled yet. This is checked my make_ready().
496 * @param env The block schedule environment.
497 * @param irn The node, which usages (successors) are to be made ready.
499 static INLINE void make_users_ready(block_sched_env_t *env, ir_node *irn)
501 const ir_edge_t *edge;
503 foreach_out_edge(irn, edge) {
504 ir_node *user = edge->src;
506 make_ready(env, user);
511 * Compare to nodes using pointer equality.
512 * @param p1 Node one.
513 * @param p2 Node two.
514 * @return 0 if they are identical.
516 static int node_cmp_func(const void *p1, const void *p2)
522 * Append an instruction to a schedule.
523 * @param env The block scheduling environment.
524 * @param irn The node to add to the schedule.
525 * @return The given node.
527 static ir_node *add_to_sched(block_sched_env_t *env, ir_node *irn)
529 /* If the node consumes/produces data, it is appended to the schedule
530 * list, otherwise, it is not put into the list */
531 if(must_appear_in_schedule(env->selector, env->selector_block_env, irn)) {
532 sched_info_t *info = get_irn_sched_info(irn);
533 INIT_LIST_HEAD(&info->list);
535 sched_add_before(env->block, irn);
537 DBG((env->dbg, LEVEL_2, "\tadding %+F\n", irn));
540 /* Insert the node in the set of all already scheduled nodes. */
541 nodeset_insert(env->already_scheduled, irn);
543 /* Remove the node from the ready set */
544 if(nodeset_find(env->ready_set, irn))
545 nodeset_remove(env->ready_set, irn);
551 * Add the proj nodes of a tuple-mode irn to the schedule immediately
552 * after the tuple-moded irn. By pinning the projs after the irn, no
553 * other nodes can create a new lifetime between the tuple-moded irn and
554 * one of its projs. This should render a realistic image of a
555 * tuple-moded irn, which in fact models a node which defines multiple
558 * @param irn The tuple-moded irn.
559 * @param list The schedule list to append all the projs.
560 * @param time The time step to which the irn and all its projs are
562 * @param obst The obstack the scheduling data structures shall be
564 * @param ready_set The ready set of the list scheduler.
565 * @param already_scheduled A set containing all nodes already
568 static void add_tuple_projs(block_sched_env_t *env, ir_node *irn)
570 const ir_edge_t *edge;
572 assert(get_irn_mode(irn) == mode_T && "Mode of node must be tuple");
574 foreach_out_edge(irn, edge) {
575 ir_node *out = edge->src;
577 assert(is_Proj(out) && "successor of a modeT node must be a proj");
579 if(get_irn_mode(out) == mode_T)
580 add_tuple_projs(env, out);
582 add_to_sched(env, out);
583 make_users_ready(env, out);
588 static ir_node *select_node(block_sched_env_t *be)
592 for (irn = nodeset_first(be->ready_set); irn; irn = nodeset_next(be->ready_set)) {
593 if (be_is_Keep(irn)) {
594 nodeset_break(be->ready_set);
599 return be->selector->select(be->selector_block_env, be->ready_set);
603 * Perform list scheduling on a block.
605 * Note, that the caller must compute a linked list of nodes in the block
606 * using the link field before calling this function.
608 * Also the outs must have been computed.
610 * @param block The block node.
611 * @param env Scheduling environment.
613 static void list_sched_block(ir_node *block, void *env_ptr)
615 sched_env_t *env = env_ptr;
616 const list_sched_selector_t *selector = env->selector;
617 ir_node *start_node = get_irg_start(get_irn_irg(block));
619 sched_info_t *info = get_irn_sched_info(block);
621 block_sched_env_t be;
622 const ir_edge_t *edge;
626 /* Initialize the block's list head that will hold the schedule. */
627 INIT_LIST_HEAD(&info->list);
629 /* Initialize the block scheduling environment */
632 be.ready_set = new_nodeset(get_irn_n_edges(block));
633 be.already_scheduled = new_nodeset(get_irn_n_edges(block));
634 be.selector = selector;
635 FIRM_DBG_REGISTER(be.dbg, "firm.be.sched");
637 if(selector->init_block)
638 be.selector_block_env = selector->init_block(env->selector_env, block);
640 DBG((be.dbg, LEVEL_1, "scheduling %+F\n", block));
642 /* Then one can add all nodes are ready to the set. */
643 foreach_out_edge(block, edge) {
644 ir_node *irn = get_edge_src_irn(edge);
646 /* Skip the end node because of keepalive edges. */
647 if(get_irn_opcode(irn) == iro_End)
650 /* Phi functions are scheduled immediately, since they only transfer
651 * data flow from the predecessors to this block. */
653 add_to_sched(&be, irn);
654 make_users_ready(&be, irn);
658 /* The start block will be scheduled as the first node */
659 else if(irn == start_node) {
660 add_to_sched(&be, irn);
661 add_tuple_projs(&be, irn);
665 /* Other nodes must have all operands in other blocks to be made
670 /* Check, if the operands of a node are not local to this block */
671 for(j = 0, m = get_irn_arity(irn); j < m; ++j) {
672 ir_node *operand = get_irn_n(irn, j);
674 if(get_nodes_block(operand) == block) {
680 /* Make the node ready, if all operands live in a foreign block */
682 DBG((be.dbg, LEVEL_2, "\timmediately ready: %+F\n", irn));
683 make_ready(&be, irn);
688 /* Increase the time, if some phi functions have been scheduled */
689 be.curr_time += phi_seen;
691 while (nodeset_count(be.ready_set) > 0) {
692 /* select a node to be scheduled and check if it was ready */
693 irn = select_node(&be);
695 DBG((be.dbg, LEVEL_3, "\tpicked node %+F\n", irn));
697 /* Add the node to the schedule. */
698 add_to_sched(&be, irn);
700 if(get_irn_mode(irn) == mode_T)
701 add_tuple_projs(&be, irn);
703 make_users_ready(&be, irn);
705 /* Increase the time step. */
708 /* remove the scheduled node from the ready list. */
709 if (nodeset_find(be.ready_set, irn))
710 nodeset_remove(be.ready_set, irn);
713 if(selector->finish_block)
714 selector->finish_block(be.selector_block_env);
716 del_nodeset(be.ready_set);
717 del_nodeset(be.already_scheduled);