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"
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;
221 /* Create the block info for this block. */
222 block_info = new_block_info(&env->obst, block);
223 n_cfgpreds = get_Block_n_cfgpreds(block);
225 /* no cfgpred -> no value active */
226 if (n_cfgpreds == 0) {
227 block_info->start_state = NULL;
231 /* for 1 pred only: simply take the the end-state of the pred */
232 if (n_cfgpreds == 1) {
233 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
234 block_info_t *pred_info;
236 /* process pred block */
237 belady(env, pred_block);
239 pred_info = get_block_info(pred_block);
241 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
242 block_info->start_state = pred_info->end_state;
246 /* Collect all values living at start of block */
247 DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
248 first = sched_first(block);
249 loop = get_irn_loop(block);
251 best_time = USES_INFINITY;
252 outer_loop_allowed = 1;
254 /* check all Phis first */
255 sched_foreach(block, node) {
258 if (arch_get_irn_register(node) != env->reg)
261 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
262 next_use = be_get_next_use(env->uses, first, node, 0);
264 if (USES_IS_INFINITE(next_use.time)) {
265 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
269 if (next_use.outermost_loop >= get_loop_depth(loop)) {
270 if (outer_loop_allowed || next_use.time < best_time) {
271 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
272 next_use.outermost_loop));
274 if (best_starter != NULL) {
275 /* spill the phi as it is not used */
276 spill_phi(env, best_starter);
279 best_time = next_use.time;
280 outer_loop_allowed = 0;
283 if (outer_loop_allowed && next_use.time < best_time) {
284 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
285 next_use.outermost_loop));
286 if (best_starter != NULL) {
287 /* spill the phi as it is not used */
288 spill_phi(env, best_starter);
291 best_time = next_use.time;
295 if (best_starter != node) {
296 /* spill the phi as it is not used */
297 spill_phi(env, best_starter);
301 /* check all Live-Ins */
302 be_lv_foreach(env->lv, block, be_lv_state_in, node) {
303 if (!mode_is_data(get_irn_mode(node)))
306 if (arch_get_irn_register(node) != env->reg)
309 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
310 next_use = be_get_next_use(env->uses, first, node, 0);
312 if (USES_IS_INFINITE(next_use.time)) {
313 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
317 if (next_use.outermost_loop >= get_loop_depth(loop)) {
318 if (outer_loop_allowed || next_use.time < best_time) {
319 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
320 next_use.outermost_loop));
322 if (best_starter != NULL && is_Phi(best_starter)) {
323 /* spill the phi as it is not used */
324 spill_phi(env, best_starter);
327 best_time = next_use.time;
328 outer_loop_allowed = 0;
331 if (outer_loop_allowed && next_use.time < best_time) {
332 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
333 next_use.outermost_loop));
334 if (best_starter != NULL && is_Phi(best_starter)) {
335 /* spill the phi as it is not used */
336 spill_phi(env, best_starter);
339 best_time = next_use.time;
344 block_info->start_state = best_starter;
350 * For the given block @p block, decide for each values
351 * whether it is used from a register or is reloaded
354 static void belady(minibelady_env_t *env, ir_node *block)
356 ir_node *current_state;
357 block_info_t *block_info;
359 /* Don't do a block twice */
360 if (irn_visited(block))
363 /* compute value to start with */
364 block_info = compute_block_start_state(env, block);
366 /* get the starting workset for this block */
367 DBG((dbg, LEVEL_3, "\n"));
368 DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
370 current_state = block_info->start_state;
371 DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
373 /* process the block from start to end */
374 DBG((dbg, LEVEL_3, "Processing...\n"));
376 sched_foreach(block, node) {
378 ir_node *need_val = NULL;
380 /* projs are handled with the tuple value.
381 * Phis are no real instr (see insert_starters()) */
382 if (is_Proj(node) || is_Phi(node)) {
386 /* check which state is desired for the node */
387 arity = get_irn_arity(node);
388 for (i = 0; i < arity; ++i) {
389 const arch_register_t *reg;
390 ir_node *in = get_irn_n(node, i);
392 if (!mode_is_data(get_irn_mode(in)))
395 reg = arch_get_irn_register(in);
396 if (reg == env->reg) {
397 assert(need_val == NULL);
399 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
402 /* create a reload to match state if necessary */
403 if (need_val != NULL && need_val != current_state) {
404 ir_node *before = node;
405 DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
406 create_reload(env, need_val, before, current_state);
407 current_state = need_val;
410 DBG((dbg, LEVEL_3, " ...%+F\n", node));
412 /* record state changes by the node */
413 if (get_irn_mode(node) == mode_T) {
414 foreach_out_edge(node, edge) {
415 const arch_register_t *reg;
416 ir_node *proj = get_edge_src_irn(edge);
418 if (!mode_is_data(get_irn_mode(proj)))
421 reg = arch_get_irn_register(proj);
422 if (reg == env->reg) {
423 current_state = proj;
424 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
428 if (mode_is_data(get_irn_mode(node))) {
429 const arch_register_t *reg = arch_get_irn_register(node);
430 if (reg == env->reg) {
431 current_state = node;
432 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
438 /* Remember end-workset for this block */
439 block_info->end_state = current_state;
440 DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
443 static void belady_walker(ir_node *block, void *data)
445 belady((minibelady_env_t*) data, block);
448 static ir_node *get_end_of_block_insertion_point(ir_node *block)
450 ir_node *last = sched_last(block);
452 /* skip Projs and Keep-alikes behind the jump... */
453 while (is_Proj(last) || be_is_Keep(last)) {
454 last = sched_prev(last);
457 if (!is_cfop(last)) {
458 last = sched_next(last);
459 /* last node must be a cfop, only exception is the start block */
460 assert(last == get_irg_start_block(get_irn_irg(block)));
467 * We must adapt the live-outs to the live-ins at each block-border.
469 static void fix_block_borders(ir_node *block, void *data)
471 minibelady_env_t *env = (minibelady_env_t*)data;
472 ir_graph *irg = get_irn_irg(block);
473 ir_node *startblock = get_irg_start_block(irg);
476 block_info_t *block_info;
478 if (block == startblock)
481 DBG((dbg, LEVEL_3, "\n"));
483 block_info = get_block_info(block);
485 DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
486 block_info->start_state));
488 /* process all pred blocks */
489 arity = get_irn_arity(block);
490 for (i = 0; i < arity; ++i) {
491 ir_node *pred = get_Block_cfgpred_block(block, i);
492 block_info_t *pred_info = get_block_info(pred);
493 ir_node *need_state = block_info->start_state;
495 if (need_state == NULL)
498 if (is_Phi(need_state) && get_nodes_block(need_state) == block) {
499 need_state = get_irn_n(need_state, i);
502 DBG((dbg, LEVEL_3, " Pred %+F (ends in %+F, we need %+F)\n", pred,
503 pred_info->end_state, need_state));
505 if (pred_info->end_state != need_state) {
506 ir_node *insert_point = get_end_of_block_insertion_point(pred);
509 DBG((dbg, LEVEL_3, " Creating reload for %+F\n", need_state));
510 create_reload(env, need_state, insert_point, pred_info->end_state);
515 void be_assure_state(ir_graph *irg, const arch_register_t *reg, void *func_env,
516 create_spill_func create_spill,
517 create_reload_func create_reload)
519 minibelady_env_t env;
521 be_lv_t *lv = be_get_irg_liveness(irg);
523 be_assure_live_sets(irg);
524 assure_loopinfo(irg);
526 obstack_init(&env.obst);
528 env.func_env = func_env;
529 env.create_spill = create_spill;
530 env.create_reload = create_reload;
531 env.lv = be_get_irg_liveness(irg);
532 env.uses = be_begin_uses(irg, env.lv);
534 ir_nodehashmap_init(&env.spill_infos);
537 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
538 inc_irg_visited(irg);
541 irg_block_walk_graph(irg, NULL, belady_walker, &env);
543 /* fix block end_states that don't match the next blocks start_state */
544 irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
546 ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
548 /* reconstruct ssa-form */
550 while (info != NULL) {
551 be_ssa_construction_env_t senv;
555 be_ssa_construction_init(&senv, irg);
556 if (sched_is_scheduled(info->value))
557 be_ssa_construction_add_copy(&senv, info->value);
558 be_ssa_construction_add_copies(&senv,
559 info->reloads, ARR_LEN(info->reloads));
560 be_ssa_construction_fix_users(&senv, info->value);
563 be_ssa_construction_update_liveness_phis(&senv, lv);
565 be_liveness_update(lv, info->value);
566 len = ARR_LEN(info->reloads);
567 for (i = 0; i < len; ++i) {
568 ir_node *reload = info->reloads[i];
569 be_liveness_update(lv, reload);
573 phis = be_ssa_construction_get_new_phis(&senv);
575 /* set register requirements for phis */
577 for (i = 0; i < len; ++i) {
578 ir_node *phi = phis[i];
579 arch_set_irn_register(phi, env.reg);
581 be_ssa_construction_destroy(&senv);
586 /* some nodes might be dead now. */
587 be_remove_dead_nodes_from_schedule(irg);
589 ir_nodehashmap_destroy(&env.spill_infos);
590 be_end_uses(env.uses);
591 obstack_free(&env.obst, NULL);
594 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state)
595 void be_init_state(void)
597 FIRM_DBG_REGISTER(dbg, "firm.be.state");