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
32 #include "irgraph_t.h"
36 #include "iredges_t.h"
39 #include "irnodeset.h"
40 #include "irnodehashmap.h"
41 #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_nodehashmap_t spill_infos;
71 be_uses_t *uses; /**< env for the next-use magic */
74 typedef struct block_info_t {
79 static inline block_info_t *new_block_info(struct obstack *obst, ir_node *block)
81 block_info_t *res = OALLOCZ(obst, block_info_t);
83 assert(is_Block(block));
84 set_irn_link(block, res);
85 mark_irn_visited(block);
90 static inline block_info_t *get_block_info(ir_node *block)
92 assert(irn_visited(block));
93 return (block_info_t*) get_irn_link(block);
96 static inline spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
98 spill_info_t *spill_info = OALLOCZ(&env->obst, spill_info_t);
99 spill_info->value = state;
100 spill_info->reloads = NEW_ARR_F(ir_node*, 0);
102 ir_nodehashmap_insert(&env->spill_infos, state, spill_info);
103 //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
105 spill_info->next = env->spills;
106 env->spills = spill_info;
111 static inline spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
113 spill_info_t *spill_info = ir_nodehashmap_get(spill_info_t, &env->spill_infos, node);
114 //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
118 static spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
120 spill_info_t *spill_info;
124 spill_info = get_spill_info(env, state);
125 if (spill_info == NULL) {
126 spill_info = create_spill_info(env, state);
127 } else if (spill_info->spill != NULL) {
131 if (sched_is_scheduled(state)) {
135 next = sched_next(after);
136 } while (is_Proj(next) || is_Phi(next) || be_is_Keep(next));
140 spill_info->spill = env->create_spill(env->func_env, state, force, after);
145 static void create_reload(minibelady_env_t *env, ir_node *state,
146 ir_node *before, ir_node *last_state)
148 spill_info_t *spill_info = create_spill(env, state, 0);
149 ir_node *spill = spill_info->spill;
152 reload = env->create_reload(env->func_env, state, spill, before,
154 ARR_APP1(ir_node*, spill_info->reloads, reload);
157 static void spill_phi(minibelady_env_t *env, ir_node *phi)
159 ir_graph *irg = get_irn_irg(phi);
160 ir_node *block = get_nodes_block(phi);
161 int arity = get_irn_arity(phi);
162 ir_node **phi_in = ALLOCAN(ir_node*, arity);
163 ir_node *dummy = new_r_Dummy(irg, mode_M);
164 ir_node *spill_to_kill = NULL;
165 spill_info_t *spill_info;
168 /* does a spill exist for the phis value? */
169 spill_info = get_spill_info(env, phi);
170 if (spill_info != NULL) {
171 spill_to_kill = spill_info->spill;
173 spill_info = create_spill_info(env, phi);
176 /* create a new phi-M with bad preds */
177 for (i = 0; i < arity; ++i) {
181 DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
184 spill_info->spill = be_new_Phi(block, arity, phi_in, mode_M,
185 arch_no_register_req);
186 sched_add_after(block, spill_info->spill);
188 if (spill_to_kill != NULL) {
189 exchange(spill_to_kill, spill_info->spill);
190 sched_remove(spill_to_kill);
193 /* create spills for the phi values */
194 for (i = 0; i < arity; ++i) {
195 ir_node *in = get_irn_n(phi, i);
196 spill_info_t *pred_spill = create_spill(env, in, 1);
197 set_irn_n(spill_info->spill, i, pred_spill->spill);
201 static void belady(minibelady_env_t *env, ir_node *block);
204 * Collects all values live-in at block @p block and all phi results in this
206 * Then it adds the best values (at most n_regs) to the blocks start_workset.
207 * The phis among the remaining values get spilled: Introduce pseudo-copies of
208 * their args to break interference and make it possible to spill them to the
211 static block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
213 block_info_t *block_info;
214 be_next_use_t next_use;
216 ir_node *best_starter, *first;
219 int outer_loop_allowed;
222 /* Create the block info for this block. */
223 block_info = new_block_info(&env->obst, block);
224 n_cfgpreds = get_Block_n_cfgpreds(block);
226 /* no cfgpred -> no value active */
227 if (n_cfgpreds == 0) {
228 block_info->start_state = NULL;
232 /* for 1 pred only: simply take the the end-state of the pred */
233 if (n_cfgpreds == 1) {
234 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
235 block_info_t *pred_info;
237 /* process pred block */
238 belady(env, pred_block);
240 pred_info = get_block_info(pred_block);
242 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
243 block_info->start_state = pred_info->end_state;
247 /* Collect all values living at start of block */
248 DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
249 first = sched_first(block);
250 loop = get_irn_loop(block);
252 best_time = USES_INFINITY;
253 outer_loop_allowed = 1;
255 /* check all Phis first */
256 sched_foreach(block, node) {
259 if (arch_get_irn_register(node) != env->reg)
262 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
263 next_use = be_get_next_use(env->uses, first, node, 0);
265 if (USES_IS_INFINITE(next_use.time)) {
266 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
270 if (next_use.outermost_loop >= get_loop_depth(loop)) {
271 if (outer_loop_allowed || next_use.time < best_time) {
272 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
273 next_use.outermost_loop));
275 if (best_starter != NULL) {
276 /* spill the phi as it is not used */
277 spill_phi(env, best_starter);
280 best_time = next_use.time;
281 outer_loop_allowed = 0;
284 if (outer_loop_allowed && next_use.time < best_time) {
285 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
286 next_use.outermost_loop));
287 if (best_starter != NULL) {
288 /* spill the phi as it is not used */
289 spill_phi(env, best_starter);
292 best_time = next_use.time;
296 if (best_starter != node) {
297 /* spill the phi as it is not used */
298 spill_phi(env, best_starter);
302 /* check all Live-Ins */
303 be_lv_foreach(env->lv, block, be_lv_state_in, i) {
304 ir_node *const node = be_lv_get_irn(env->lv, block, i);
306 if (!mode_is_data(get_irn_mode(node)))
309 if (arch_get_irn_register(node) != env->reg)
312 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
313 next_use = be_get_next_use(env->uses, first, node, 0);
315 if (USES_IS_INFINITE(next_use.time)) {
316 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
320 if (next_use.outermost_loop >= get_loop_depth(loop)) {
321 if (outer_loop_allowed || next_use.time < best_time) {
322 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
323 next_use.outermost_loop));
325 if (best_starter != NULL && is_Phi(best_starter)) {
326 /* spill the phi as it is not used */
327 spill_phi(env, best_starter);
330 best_time = next_use.time;
331 outer_loop_allowed = 0;
334 if (outer_loop_allowed && next_use.time < best_time) {
335 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
336 next_use.outermost_loop));
337 if (best_starter != NULL && is_Phi(best_starter)) {
338 /* spill the phi as it is not used */
339 spill_phi(env, best_starter);
342 best_time = next_use.time;
347 block_info->start_state = best_starter;
353 * For the given block @p block, decide for each values
354 * whether it is used from a register or is reloaded
357 static void belady(minibelady_env_t *env, ir_node *block)
359 ir_node *current_state;
360 block_info_t *block_info;
362 /* Don't do a block twice */
363 if (irn_visited(block))
366 /* compute value to start with */
367 block_info = compute_block_start_state(env, block);
369 /* get the starting workset for this block */
370 DBG((dbg, LEVEL_3, "\n"));
371 DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
373 current_state = block_info->start_state;
374 DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
376 /* process the block from start to end */
377 DBG((dbg, LEVEL_3, "Processing...\n"));
379 sched_foreach(block, node) {
381 ir_node *need_val = NULL;
383 /* projs are handled with the tuple value.
384 * Phis are no real instr (see insert_starters()) */
385 if (is_Proj(node) || is_Phi(node)) {
389 /* check which state is desired for the node */
390 arity = get_irn_arity(node);
391 for (i = 0; i < arity; ++i) {
392 const arch_register_t *reg;
393 ir_node *in = get_irn_n(node, i);
395 if (!mode_is_data(get_irn_mode(in)))
398 reg = arch_get_irn_register(in);
399 if (reg == env->reg) {
400 assert(need_val == NULL);
402 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
405 /* create a reload to match state if necessary */
406 if (need_val != NULL && need_val != current_state) {
407 ir_node *before = node;
408 DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
409 create_reload(env, need_val, before, current_state);
410 current_state = need_val;
413 DBG((dbg, LEVEL_3, " ...%+F\n", node));
415 /* record state changes by the node */
416 if (get_irn_mode(node) == mode_T) {
417 foreach_out_edge(node, edge) {
418 const arch_register_t *reg;
419 ir_node *proj = get_edge_src_irn(edge);
421 if (!mode_is_data(get_irn_mode(proj)))
424 reg = arch_get_irn_register(proj);
425 if (reg == env->reg) {
426 current_state = proj;
427 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
431 if (mode_is_data(get_irn_mode(node))) {
432 const arch_register_t *reg = arch_get_irn_register(node);
433 if (reg == env->reg) {
434 current_state = node;
435 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
441 /* Remember end-workset for this block */
442 block_info->end_state = current_state;
443 DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
446 static void belady_walker(ir_node *block, void *data)
448 belady((minibelady_env_t*) data, block);
451 static ir_node *get_end_of_block_insertion_point(ir_node *block)
453 ir_node *last = sched_last(block);
455 /* skip Projs and Keep-alikes behind the jump... */
456 while (is_Proj(last) || be_is_Keep(last)) {
457 last = sched_prev(last);
460 if (!is_cfop(last)) {
461 last = sched_next(last);
462 /* last node must be a cfop, only exception is the start block */
463 assert(last == get_irg_start_block(get_irn_irg(block)));
470 * We must adapt the live-outs to the live-ins at each block-border.
472 static void fix_block_borders(ir_node *block, void *data)
474 minibelady_env_t *env = (minibelady_env_t*)data;
475 ir_graph *irg = get_irn_irg(block);
476 ir_node *startblock = get_irg_start_block(irg);
479 block_info_t *block_info;
481 if (block == startblock)
484 DBG((dbg, LEVEL_3, "\n"));
486 block_info = get_block_info(block);
488 DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
489 block_info->start_state));
491 /* process all pred blocks */
492 arity = get_irn_arity(block);
493 for (i = 0; i < arity; ++i) {
494 ir_node *pred = get_Block_cfgpred_block(block, i);
495 block_info_t *pred_info = get_block_info(pred);
496 ir_node *need_state = block_info->start_state;
498 if (need_state == NULL)
501 if (is_Phi(need_state) && get_nodes_block(need_state) == block) {
502 need_state = get_irn_n(need_state, i);
505 DBG((dbg, LEVEL_3, " Pred %+F (ends in %+F, we need %+F)\n", pred,
506 pred_info->end_state, need_state));
508 if (pred_info->end_state != need_state) {
509 ir_node *insert_point = get_end_of_block_insertion_point(pred);
512 DBG((dbg, LEVEL_3, " Creating reload for %+F\n", need_state));
513 create_reload(env, need_state, insert_point, pred_info->end_state);
518 void be_assure_state(ir_graph *irg, const arch_register_t *reg, void *func_env,
519 create_spill_func create_spill,
520 create_reload_func create_reload)
522 minibelady_env_t env;
524 be_lv_t *lv = be_get_irg_liveness(irg);
526 be_assure_live_sets(irg);
527 assure_loopinfo(irg);
529 obstack_init(&env.obst);
531 env.func_env = func_env;
532 env.create_spill = create_spill;
533 env.create_reload = create_reload;
534 env.lv = be_get_irg_liveness(irg);
535 env.uses = be_begin_uses(irg, env.lv);
537 ir_nodehashmap_init(&env.spill_infos);
540 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
541 inc_irg_visited(irg);
544 irg_block_walk_graph(irg, NULL, belady_walker, &env);
546 /* fix block end_states that don't match the next blocks start_state */
547 irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
549 ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
551 /* reconstruct ssa-form */
553 while (info != NULL) {
554 be_ssa_construction_env_t senv;
558 be_ssa_construction_init(&senv, irg);
559 if (sched_is_scheduled(info->value))
560 be_ssa_construction_add_copy(&senv, info->value);
561 be_ssa_construction_add_copies(&senv,
562 info->reloads, ARR_LEN(info->reloads));
563 be_ssa_construction_fix_users(&senv, info->value);
566 be_ssa_construction_update_liveness_phis(&senv, lv);
568 be_liveness_update(lv, info->value);
569 len = ARR_LEN(info->reloads);
570 for (i = 0; i < len; ++i) {
571 ir_node *reload = info->reloads[i];
572 be_liveness_update(lv, reload);
576 phis = be_ssa_construction_get_new_phis(&senv);
578 /* set register requirements for phis */
580 for (i = 0; i < len; ++i) {
581 ir_node *phi = phis[i];
582 arch_set_irn_register(phi, env.reg);
584 be_ssa_construction_destroy(&senv);
589 /* some nodes might be dead now. */
590 be_remove_dead_nodes_from_schedule(irg);
592 ir_nodehashmap_destroy(&env.spill_infos);
593 be_end_uses(env.uses);
594 obstack_free(&env.obst, NULL);
597 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state)
598 void be_init_state(void)
600 FIRM_DBG_REGISTER(dbg, "firm.be.state");