2 * Copyright (C) 1995-2008 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief Handles state switching. This is basically the belady spill
23 * algorithm optimized for the 1-register case.
24 * @author Matthias Braun
33 #include "irgraph_t.h"
37 #include "iredges_t.h"
40 #include "irnodeset.h"
41 #include "irnodemap.h"
42 #include "adt/cpset.h"
50 #include "bessaconstr.h"
52 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
54 typedef struct spill_info_t {
55 struct spill_info_t *next;
61 typedef struct minibelady_env_t {
63 const arch_register_t *reg;
66 create_reload_func create_reload;
67 create_spill_func create_spill;
69 ir_nodemap_t spill_infos;
71 be_uses_t *uses; /**< env for the next-use magic */
74 typedef struct block_info_t {
80 block_info_t *new_block_info(struct obstack *obst, ir_node *block)
82 block_info_t *res = OALLOCZ(obst, block_info_t);
84 assert(is_Block(block));
85 set_irn_link(block, res);
86 mark_irn_visited(block);
92 block_info_t *get_block_info(ir_node *block)
94 assert(irn_visited(block));
95 return (block_info_t*) get_irn_link(block);
99 spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
101 spill_info_t *spill_info = OALLOCZ(&env->obst, spill_info_t);
102 spill_info->value = state;
103 spill_info->reloads = NEW_ARR_F(ir_node*, 0);
105 ir_nodemap_insert(&env->spill_infos, state, spill_info);
106 //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
108 spill_info->next = env->spills;
109 env->spills = spill_info;
115 spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
117 spill_info_t *spill_info
118 = (spill_info_t*) ir_nodemap_get(&env->spill_infos, node);
119 //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
124 spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
126 spill_info_t *spill_info;
130 spill_info = get_spill_info(env, state);
131 if(spill_info == NULL) {
132 spill_info = create_spill_info(env, state);
133 } else if(spill_info->spill != NULL) {
137 if(sched_is_scheduled(state)) {
141 next = sched_next(after);
142 } while(is_Proj(next) || is_Phi(next) || be_is_Keep(next));
146 spill_info->spill = env->create_spill(env->func_env, state, force, after);
152 void create_reload(minibelady_env_t *env, ir_node *state, ir_node *before,
155 spill_info_t *spill_info = create_spill(env, state, 0);
156 ir_node *spill = spill_info->spill;
159 reload = env->create_reload(env->func_env, state, spill, before,
161 ARR_APP1(ir_node*, spill_info->reloads, reload);
165 void spill_phi(minibelady_env_t *env, ir_node *phi)
167 ir_graph *irg = get_irn_irg(phi);
168 ir_node *block = get_nodes_block(phi);
169 int arity = get_irn_arity(phi);
170 ir_node **in = ALLOCAN(ir_node*, arity);
171 ir_node *spill_to_kill = NULL;
172 spill_info_t *spill_info;
175 /* does a spill exist for the phis value? */
176 spill_info = get_spill_info(env, phi);
177 if(spill_info != NULL) {
178 spill_to_kill = spill_info->spill;
180 spill_info = create_spill_info(env, phi);
183 /* create a new phi-M with bad preds */
184 for(i = 0; i < arity; ++i) {
185 in[i] = new_r_Unknown(irg, mode_M);
188 DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
191 spill_info->spill = new_r_Phi(block, arity, in, mode_M);
193 if(spill_to_kill != NULL) {
194 exchange(spill_to_kill, spill_info->spill);
195 sched_remove(spill_to_kill);
198 /* create spills for the phi values */
199 for(i = 0; i < arity; ++i) {
200 ir_node *in = get_irn_n(phi, i);
201 spill_info_t *pred_spill = create_spill(env, in, 1);
202 set_irn_n(spill_info->spill, i, pred_spill->spill);
207 void belady(minibelady_env_t *env, ir_node *block);
210 * Collects all values live-in at block @p block and all phi results in this
212 * Then it adds the best values (at most n_regs) to the blocks start_workset.
213 * The phis among the remaining values get spilled: Introduce psudo-copies of
214 * their args to break interference and make it possible to spill them to the
218 block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
220 block_info_t *block_info;
221 be_next_use_t next_use;
223 ir_node *best_starter, *first;
227 int outer_loop_allowed;
230 /* Create the block info for this block. */
231 block_info = new_block_info(&env->obst, block);
232 n_cfgpreds = get_Block_n_cfgpreds(block);
234 /* no cfgpred -> no value active */
235 if(n_cfgpreds == 0) {
236 block_info->start_state = NULL;
240 /* for 1 pred only: simply take the the end-state of the pred */
241 if(n_cfgpreds == 1) {
242 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
243 block_info_t *pred_info;
245 /* process pred block */
246 belady(env, pred_block);
248 pred_info = get_block_info(pred_block);
250 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
251 block_info->start_state = pred_info->end_state;
255 /* Collect all values living at start of block */
256 DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
257 first = sched_first(block);
258 loop = get_irn_loop(block);
260 best_time = USES_INFINITY;
261 outer_loop_allowed = 1;
263 /* check all Phis first */
264 sched_foreach(block, node) {
267 if (arch_get_irn_register(node) != env->reg)
270 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
271 next_use = be_get_next_use(env->uses, first, 0, node, 0);
273 if(USES_IS_INFINITE(next_use.time)) {
274 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
278 if(next_use.outermost_loop >= get_loop_depth(loop)) {
279 if(outer_loop_allowed || next_use.time < best_time) {
280 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
281 next_use.outermost_loop));
283 if(best_starter != NULL) {
284 /* spill the phi as it is not used */
285 spill_phi(env, best_starter);
288 best_time = next_use.time;
289 outer_loop_allowed = 0;
292 if(outer_loop_allowed && next_use.time < best_time) {
293 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
294 next_use.outermost_loop));
295 if(best_starter != NULL) {
296 /* spill the phi as it is not used */
297 spill_phi(env, best_starter);
300 best_time = next_use.time;
304 if(best_starter != node) {
305 /* spill the phi as it is not used */
306 spill_phi(env, best_starter);
310 /* check all Live-Ins */
311 be_lv_foreach(env->lv, block, be_lv_state_in, i) {
312 node = be_lv_get_irn(env->lv, block, i);
314 if(!mode_is_data(get_irn_mode(node)))
317 if (arch_get_irn_register(node) != env->reg)
320 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
321 next_use = be_get_next_use(env->uses, first, 0, node, 0);
323 if(USES_IS_INFINITE(next_use.time)) {
324 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
328 if(next_use.outermost_loop >= get_loop_depth(loop)) {
329 if(outer_loop_allowed || next_use.time < best_time) {
330 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
331 next_use.outermost_loop));
333 if(best_starter != NULL && is_Phi(best_starter)) {
334 /* spill the phi as it is not used */
335 spill_phi(env, best_starter);
338 best_time = next_use.time;
339 outer_loop_allowed = 0;
342 if(outer_loop_allowed && next_use.time < best_time) {
343 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
344 next_use.outermost_loop));
345 if(best_starter != NULL && is_Phi(best_starter)) {
346 /* spill the phi as it is not used */
347 spill_phi(env, best_starter);
350 best_time = next_use.time;
355 block_info->start_state = best_starter;
361 * For the given block @p block, decide for each values
362 * whether it is used from a register or is reloaded
366 void belady(minibelady_env_t *env, ir_node *block)
368 ir_node *current_state;
370 block_info_t *block_info;
372 /* Don't do a block twice */
373 if(irn_visited(block))
376 /* compute value to start with */
377 block_info = compute_block_start_state(env, block);
379 /* get the starting workset for this block */
380 DBG((dbg, LEVEL_3, "\n"));
381 DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
383 current_state = block_info->start_state;
384 DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
386 /* process the block from start to end */
387 DBG((dbg, LEVEL_3, "Processing...\n"));
389 sched_foreach(block, node) {
391 ir_node *need_val = NULL;
393 /* projs are handled with the tuple value.
394 * Phis are no real instr (see insert_starters()) */
395 if (is_Proj(node) || is_Phi(node)) {
399 /* check which state is desired for the node */
400 arity = get_irn_arity(node);
401 for(i = 0; i < arity; ++i) {
402 const arch_register_t *reg;
403 ir_node *in = get_irn_n(node, i);
405 if(!mode_is_data(get_irn_mode(in)))
408 reg = arch_get_irn_register(in);
409 if(reg == env->reg) {
410 assert(need_val == NULL);
412 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
415 /* create a reload to match state if necessary */
416 if(need_val != NULL && need_val != current_state) {
417 DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
418 create_reload(env, need_val, node, current_state);
419 current_state = need_val;
422 DBG((dbg, LEVEL_3, " ...%+F\n", node));
424 /* record state changes by the node */
425 if (get_irn_mode(node) == mode_T) {
426 const ir_edge_t *edge;
428 foreach_out_edge(node, edge) {
429 const arch_register_t *reg;
430 ir_node *proj = get_edge_src_irn(edge);
432 if(!mode_is_data(get_irn_mode(proj)))
435 reg = arch_get_irn_register(proj);
436 if(reg == env->reg) {
437 current_state = proj;
438 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
442 if(mode_is_data(get_irn_mode(node))) {
443 const arch_register_t *reg = arch_get_irn_register(node);
444 if(reg == env->reg) {
445 current_state = node;
446 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
452 /* Remember end-workset for this block */
453 block_info->end_state = current_state;
454 DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
458 void belady_walker(ir_node *block, void *data)
460 belady((minibelady_env_t*) data, block);
464 ir_node *get_end_of_block_insertion_point(ir_node *block)
466 ir_node *last = sched_last(block);
468 /* skip Projs and Keep-alikes behind the jump... */
469 while(is_Proj(last) || be_is_Keep(last)) {
470 last = sched_prev(last);
474 last = sched_next(last);
475 /* last node must be a cfop, only exception is the start block */
476 assert(last == get_irg_start_block(get_irn_irg(block)));
483 * We must adapt the live-outs to the live-ins at each block-border.
486 void fix_block_borders(ir_node *block, void *data) {
487 minibelady_env_t *env = data;
488 ir_graph *irg = get_irn_irg(block);
489 ir_node *startblock = get_irg_start_block(irg);
492 block_info_t *block_info;
494 if(block == startblock)
497 DBG((dbg, LEVEL_3, "\n"));
499 block_info = get_block_info(block);
501 DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
502 block_info->start_state));
504 /* process all pred blocks */
505 arity = get_irn_arity(block);
506 for (i = 0; i < arity; ++i) {
507 ir_node *pred = get_Block_cfgpred_block(block, i);
508 block_info_t *pred_info = get_block_info(pred);
509 ir_node *need_state = block_info->start_state;
511 if(need_state == NULL)
514 if(is_Phi(need_state) && get_nodes_block(need_state) == block) {
515 need_state = get_irn_n(need_state, i);
518 DBG((dbg, LEVEL_3, " Pred %+F (ends in %+F, we need %+F)\n", pred,
519 pred_info->end_state, need_state));
521 if(pred_info->end_state != need_state) {
522 ir_node *insert_point = get_end_of_block_insertion_point(pred);
525 DBG((dbg, LEVEL_3, " Creating reload for %+F\n", need_state));
526 create_reload(env, need_state, insert_point, pred_info->end_state);
531 void be_assure_state(be_irg_t *birg, const arch_register_t *reg, void *func_env,
532 create_spill_func create_spill,
533 create_reload_func create_reload) {
534 minibelady_env_t env;
535 ir_graph *irg = be_get_birg_irg(birg);
537 be_lv_t *lv = be_assure_liveness(birg);
539 be_liveness_assure_sets(lv);
540 /* construct control flow loop tree */
541 if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
542 construct_cf_backedges(irg);
545 obstack_init(&env.obst);
547 env.func_env = func_env;
548 env.create_spill = create_spill;
549 env.create_reload = create_reload;
550 env.lv = be_get_birg_liveness(birg);
551 env.uses = be_begin_uses(irg, env.lv);
553 ir_nodemap_init(&env.spill_infos);
556 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
557 inc_irg_visited(irg);
560 irg_block_walk_graph(irg, NULL, belady_walker, &env);
562 /* fix block end_states that don't match the next blocks start_state */
563 irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
565 ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
567 /* reconstruct ssa-form */
569 while(info != NULL) {
570 be_ssa_construction_env_t senv;
574 be_ssa_construction_init(&senv, birg);
575 if(sched_is_scheduled(info->value))
576 be_ssa_construction_add_copy(&senv, info->value);
577 be_ssa_construction_add_copies(&senv,
578 info->reloads, ARR_LEN(info->reloads));
579 be_ssa_construction_fix_users(&senv, info->value);
582 be_ssa_construction_update_liveness_phis(&senv, lv);
584 be_liveness_update(lv, info->value);
585 len = ARR_LEN(info->reloads);
586 for(i = 0; i < len; ++i) {
587 ir_node *reload = info->reloads[i];
588 be_liveness_update(lv, reload);
592 phis = be_ssa_construction_get_new_phis(&senv);
594 /* set register requirements for phis */
596 for(i = 0; i < len; ++i) {
597 ir_node *phi = phis[i];
598 arch_set_irn_register(phi, env.reg);
600 be_ssa_construction_destroy(&senv);
605 /* some nodes might be dead now. */
606 be_remove_dead_nodes_from_schedule(birg);
608 ir_nodemap_destroy(&env.spill_infos);
609 be_end_uses(env.uses);
610 obstack_free(&env.obst, NULL);
613 void be_init_state(void)
615 FIRM_DBG_REGISTER(dbg, "firm.be.state");
618 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);