2 * Copyright (C) 1995-2011 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"
51 #include "bessaconstr.h"
53 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
55 typedef struct spill_info_t {
56 struct spill_info_t *next;
62 typedef struct minibelady_env_t {
64 const arch_register_t *reg;
67 create_reload_func create_reload;
68 create_spill_func create_spill;
70 ir_nodemap_t spill_infos;
72 be_uses_t *uses; /**< env for the next-use magic */
75 typedef struct block_info_t {
80 static inline 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);
91 static inline block_info_t *get_block_info(ir_node *block)
93 assert(irn_visited(block));
94 return (block_info_t*) get_irn_link(block);
97 static inline spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
99 spill_info_t *spill_info = OALLOCZ(&env->obst, spill_info_t);
100 spill_info->value = state;
101 spill_info->reloads = NEW_ARR_F(ir_node*, 0);
103 ir_nodemap_insert(&env->spill_infos, state, spill_info);
104 //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
106 spill_info->next = env->spills;
107 env->spills = spill_info;
112 static inline spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
114 spill_info_t *spill_info
115 = (spill_info_t*) ir_nodemap_get(&env->spill_infos, node);
116 //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
120 static spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
122 spill_info_t *spill_info;
126 spill_info = get_spill_info(env, state);
127 if (spill_info == NULL) {
128 spill_info = create_spill_info(env, state);
129 } else if (spill_info->spill != NULL) {
133 if (sched_is_scheduled(state)) {
137 next = sched_next(after);
138 } while (is_Proj(next) || is_Phi(next) || be_is_Keep(next)
139 || (arch_irn_get_flags(next) & arch_irn_flags_prolog));
143 spill_info->spill = env->create_spill(env->func_env, state, force, after);
148 static void create_reload(minibelady_env_t *env, ir_node *state,
149 ir_node *before, ir_node *last_state)
151 spill_info_t *spill_info = create_spill(env, state, 0);
152 ir_node *spill = spill_info->spill;
155 reload = env->create_reload(env->func_env, state, spill, before,
157 ARR_APP1(ir_node*, spill_info->reloads, reload);
160 static void spill_phi(minibelady_env_t *env, ir_node *phi)
162 ir_graph *irg = get_irn_irg(phi);
163 ir_node *block = get_nodes_block(phi);
164 int arity = get_irn_arity(phi);
165 ir_node **in = ALLOCAN(ir_node*, arity);
166 ir_node *dummy = new_r_Dummy(irg, mode_M);
167 ir_node *spill_to_kill = NULL;
168 spill_info_t *spill_info;
171 /* does a spill exist for the phis value? */
172 spill_info = get_spill_info(env, phi);
173 if (spill_info != NULL) {
174 spill_to_kill = spill_info->spill;
176 spill_info = create_spill_info(env, phi);
179 /* create a new phi-M with bad preds */
180 for (i = 0; i < arity; ++i) {
184 DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
187 spill_info->spill = be_new_Phi(block, arity, in, mode_M, NULL);
188 sched_add_after(block, spill_info->spill);
190 if (spill_to_kill != NULL) {
191 exchange(spill_to_kill, spill_info->spill);
192 sched_remove(spill_to_kill);
195 /* create spills for the phi values */
196 for (i = 0; i < arity; ++i) {
197 ir_node *in = get_irn_n(phi, i);
198 spill_info_t *pred_spill = create_spill(env, in, 1);
199 set_irn_n(spill_info->spill, i, pred_spill->spill);
203 static void belady(minibelady_env_t *env, ir_node *block);
206 * Collects all values live-in at block @p block and all phi results in this
208 * Then it adds the best values (at most n_regs) to the blocks start_workset.
209 * The phis among the remaining values get spilled: Introduce pseudo-copies of
210 * their args to break interference and make it possible to spill them to the
213 static block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
215 block_info_t *block_info;
216 be_next_use_t next_use;
218 ir_node *best_starter, *first;
222 int outer_loop_allowed;
225 /* Create the block info for this block. */
226 block_info = new_block_info(&env->obst, block);
227 n_cfgpreds = get_Block_n_cfgpreds(block);
229 /* no cfgpred -> no value active */
230 if (n_cfgpreds == 0) {
231 block_info->start_state = NULL;
235 /* for 1 pred only: simply take the the end-state of the pred */
236 if (n_cfgpreds == 1) {
237 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
238 block_info_t *pred_info;
240 /* process pred block */
241 belady(env, pred_block);
243 pred_info = get_block_info(pred_block);
245 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
246 block_info->start_state = pred_info->end_state;
250 /* Collect all values living at start of block */
251 DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
252 first = sched_first(block);
253 loop = get_irn_loop(block);
255 best_time = USES_INFINITY;
256 outer_loop_allowed = 1;
258 /* check all Phis first */
259 sched_foreach(block, node) {
262 if (arch_get_irn_register(node) != env->reg)
265 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
266 next_use = be_get_next_use(env->uses, first, node, 0);
268 if (USES_IS_INFINITE(next_use.time)) {
269 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
273 if (next_use.outermost_loop >= get_loop_depth(loop)) {
274 if (outer_loop_allowed || next_use.time < best_time) {
275 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
276 next_use.outermost_loop));
278 if (best_starter != NULL) {
279 /* spill the phi as it is not used */
280 spill_phi(env, best_starter);
283 best_time = next_use.time;
284 outer_loop_allowed = 0;
287 if (outer_loop_allowed && next_use.time < best_time) {
288 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
289 next_use.outermost_loop));
290 if (best_starter != NULL) {
291 /* spill the phi as it is not used */
292 spill_phi(env, best_starter);
295 best_time = next_use.time;
299 if (best_starter != node) {
300 /* spill the phi as it is not used */
301 spill_phi(env, best_starter);
305 /* check all Live-Ins */
306 be_lv_foreach(env->lv, block, be_lv_state_in, i) {
307 node = be_lv_get_irn(env->lv, block, i);
309 if (!mode_is_data(get_irn_mode(node)))
312 if (arch_get_irn_register(node) != env->reg)
315 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
316 next_use = be_get_next_use(env->uses, first, node, 0);
318 if (USES_IS_INFINITE(next_use.time)) {
319 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
323 if (next_use.outermost_loop >= get_loop_depth(loop)) {
324 if (outer_loop_allowed || next_use.time < best_time) {
325 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
326 next_use.outermost_loop));
328 if (best_starter != NULL && is_Phi(best_starter)) {
329 /* spill the phi as it is not used */
330 spill_phi(env, best_starter);
333 best_time = next_use.time;
334 outer_loop_allowed = 0;
337 if (outer_loop_allowed && next_use.time < best_time) {
338 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
339 next_use.outermost_loop));
340 if (best_starter != NULL && is_Phi(best_starter)) {
341 /* spill the phi as it is not used */
342 spill_phi(env, best_starter);
345 best_time = next_use.time;
350 block_info->start_state = best_starter;
355 static ir_node *get_reload_point(ir_node *before)
358 ir_node *prev = sched_prev(before);
359 if (! (arch_irn_get_flags(prev) & arch_irn_flags_epilog))
367 * For the given block @p block, decide for each values
368 * whether it is used from a register or is reloaded
371 static void belady(minibelady_env_t *env, ir_node *block)
373 ir_node *current_state;
375 block_info_t *block_info;
377 /* Don't do a block twice */
378 if (irn_visited(block))
381 /* compute value to start with */
382 block_info = compute_block_start_state(env, block);
384 /* get the starting workset for this block */
385 DBG((dbg, LEVEL_3, "\n"));
386 DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
388 current_state = block_info->start_state;
389 DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
391 /* process the block from start to end */
392 DBG((dbg, LEVEL_3, "Processing...\n"));
394 sched_foreach(block, node) {
396 ir_node *need_val = NULL;
398 /* projs are handled with the tuple value.
399 * Phis are no real instr (see insert_starters()) */
400 if (is_Proj(node) || is_Phi(node)) {
404 /* check which state is desired for the node */
405 arity = get_irn_arity(node);
406 for (i = 0; i < arity; ++i) {
407 const arch_register_t *reg;
408 ir_node *in = get_irn_n(node, i);
410 if (!mode_is_data(get_irn_mode(in)))
413 reg = arch_get_irn_register(in);
414 if (reg == env->reg) {
415 assert(need_val == NULL);
417 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
420 /* create a reload to match state if necessary */
421 if (need_val != NULL && need_val != current_state) {
422 ir_node *before = get_reload_point(node);
423 DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
424 create_reload(env, need_val, before, current_state);
425 current_state = need_val;
428 DBG((dbg, LEVEL_3, " ...%+F\n", node));
430 /* record state changes by the node */
431 if (get_irn_mode(node) == mode_T) {
432 const ir_edge_t *edge;
434 foreach_out_edge(node, edge) {
435 const arch_register_t *reg;
436 ir_node *proj = get_edge_src_irn(edge);
438 if (!mode_is_data(get_irn_mode(proj)))
441 reg = arch_get_irn_register(proj);
442 if (reg == env->reg) {
443 current_state = proj;
444 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
448 if (mode_is_data(get_irn_mode(node))) {
449 const arch_register_t *reg = arch_get_irn_register(node);
450 if (reg == env->reg) {
451 current_state = node;
452 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
458 /* Remember end-workset for this block */
459 block_info->end_state = current_state;
460 DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
463 static void belady_walker(ir_node *block, void *data)
465 belady((minibelady_env_t*) data, block);
468 static ir_node *get_end_of_block_insertion_point(ir_node *block)
470 ir_node *last = sched_last(block);
472 /* skip Projs and Keep-alikes behind the jump... */
473 while (is_Proj(last) || be_is_Keep(last)) {
474 last = sched_prev(last);
477 if (!is_cfop(last)) {
478 last = sched_next(last);
479 /* last node must be a cfop, only exception is the start block */
480 assert(last == get_irg_start_block(get_irn_irg(block)));
487 * We must adapt the live-outs to the live-ins at each block-border.
489 static void fix_block_borders(ir_node *block, void *data)
491 minibelady_env_t *env = (minibelady_env_t*)data;
492 ir_graph *irg = get_irn_irg(block);
493 ir_node *startblock = get_irg_start_block(irg);
496 block_info_t *block_info;
498 if (block == startblock)
501 DBG((dbg, LEVEL_3, "\n"));
503 block_info = get_block_info(block);
505 DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
506 block_info->start_state));
508 /* process all pred blocks */
509 arity = get_irn_arity(block);
510 for (i = 0; i < arity; ++i) {
511 ir_node *pred = get_Block_cfgpred_block(block, i);
512 block_info_t *pred_info = get_block_info(pred);
513 ir_node *need_state = block_info->start_state;
515 if (need_state == NULL)
518 if (is_Phi(need_state) && get_nodes_block(need_state) == block) {
519 need_state = get_irn_n(need_state, i);
522 DBG((dbg, LEVEL_3, " Pred %+F (ends in %+F, we need %+F)\n", pred,
523 pred_info->end_state, need_state));
525 if (pred_info->end_state != need_state) {
526 ir_node *insert_point = get_end_of_block_insertion_point(pred);
529 DBG((dbg, LEVEL_3, " Creating reload for %+F\n", need_state));
530 create_reload(env, need_state, insert_point, pred_info->end_state);
535 void be_assure_state(ir_graph *irg, const arch_register_t *reg, void *func_env,
536 create_spill_func create_spill,
537 create_reload_func create_reload)
539 minibelady_env_t env;
541 be_lv_t *lv = be_assure_liveness(irg);
543 be_liveness_assure_sets(lv);
544 /* construct control flow loop tree */
545 if (! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
546 construct_cf_backedges(irg);
549 obstack_init(&env.obst);
551 env.func_env = func_env;
552 env.create_spill = create_spill;
553 env.create_reload = create_reload;
554 env.lv = be_get_irg_liveness(irg);
555 env.uses = be_begin_uses(irg, env.lv);
557 ir_nodemap_init(&env.spill_infos);
560 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
561 inc_irg_visited(irg);
564 irg_block_walk_graph(irg, NULL, belady_walker, &env);
566 /* fix block end_states that don't match the next blocks start_state */
567 irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
569 ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
571 /* reconstruct ssa-form */
573 while (info != NULL) {
574 be_ssa_construction_env_t senv;
578 be_ssa_construction_init(&senv, irg);
579 if (sched_is_scheduled(info->value))
580 be_ssa_construction_add_copy(&senv, info->value);
581 be_ssa_construction_add_copies(&senv,
582 info->reloads, ARR_LEN(info->reloads));
583 be_ssa_construction_fix_users(&senv, info->value);
586 be_ssa_construction_update_liveness_phis(&senv, lv);
588 be_liveness_update(lv, info->value);
589 len = ARR_LEN(info->reloads);
590 for (i = 0; i < len; ++i) {
591 ir_node *reload = info->reloads[i];
592 be_liveness_update(lv, reload);
596 phis = be_ssa_construction_get_new_phis(&senv);
598 /* set register requirements for phis */
600 for (i = 0; i < len; ++i) {
601 ir_node *phi = phis[i];
602 arch_set_irn_register(phi, env.reg);
604 be_ssa_construction_destroy(&senv);
609 /* some nodes might be dead now. */
610 be_remove_dead_nodes_from_schedule(irg);
612 ir_nodemap_destroy(&env.spill_infos);
613 be_end_uses(env.uses);
614 obstack_free(&env.obst, NULL);
617 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);
618 void be_init_state(void)
620 FIRM_DBG_REGISTER(dbg, "firm.be.state");