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"
46 #include "besched_t.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 = obstack_alloc(obst, sizeof(*res));
83 memset(res, 0, sizeof(res[0]));
85 assert(is_Block(block));
86 set_irn_link(block, res);
87 mark_irn_visited(block);
93 block_info_t *get_block_info(ir_node *block)
95 assert(irn_visited(block));
96 return (block_info_t*) get_irn_link(block);
100 spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
102 spill_info_t *spill_info = obstack_alloc(&env->obst, sizeof(spill_info[0]));
103 memset(spill_info, 0, sizeof(spill_info[0]));
104 spill_info->value = state;
105 spill_info->reloads = NEW_ARR_F(ir_node*, 0);
107 ir_nodemap_insert(&env->spill_infos, state, spill_info);
108 //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
110 spill_info->next = env->spills;
111 env->spills = spill_info;
117 spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
119 spill_info_t *spill_info
120 = (spill_info_t*) ir_nodemap_get(&env->spill_infos, node);
121 //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
126 spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
128 spill_info_t *spill_info;
132 spill_info = get_spill_info(env, state);
133 if(spill_info == NULL) {
134 spill_info = create_spill_info(env, state);
135 } else if(spill_info->spill != NULL) {
139 if(sched_is_scheduled(state)) {
143 next = sched_next(after);
144 } while(is_Proj(next) || is_Phi(next) || be_is_Keep(next));
148 spill_info->spill = env->create_spill(env->func_env, state, force, after);
154 void create_reload(minibelady_env_t *env, ir_node *state, ir_node *before,
157 spill_info_t *spill_info = create_spill(env, state, 0);
158 ir_node *spill = spill_info->spill;
161 reload = env->create_reload(env->func_env, state, spill, before,
163 ARR_APP1(ir_node*, spill_info->reloads, reload);
167 void spill_phi(minibelady_env_t *env, ir_node *phi)
169 ir_graph *irg = get_irn_irg(phi);
170 ir_node *block = get_nodes_block(phi);
171 int i, arity = get_irn_arity(phi);
172 ir_node **in = alloca(arity * sizeof(in[0]));
173 ir_node *spill_to_kill = NULL;
174 spill_info_t *spill_info;
176 /* does a spill exist for the phis value? */
177 spill_info = get_spill_info(env, phi);
178 if(spill_info != NULL) {
179 spill_to_kill = spill_info->spill;
181 spill_info = create_spill_info(env, phi);
184 /* create a new phi-M with bad preds */
185 for(i = 0; i < arity; ++i) {
186 in[i] = new_r_Unknown(irg, mode_M);
189 DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
192 spill_info->spill = new_r_Phi(irg, block, arity, in, mode_M);
194 if(spill_to_kill != NULL) {
195 exchange(spill_to_kill, spill_info->spill);
196 sched_remove(spill_to_kill);
199 /* create spills for the phi values */
200 for(i = 0; i < arity; ++i) {
201 ir_node *in = get_irn_n(phi, i);
202 spill_info_t *pred_spill = create_spill(env, in, 1);
203 set_irn_n(spill_info->spill, i, pred_spill->spill);
208 void belady(minibelady_env_t *env, ir_node *block);
211 * Collects all values live-in at block @p block and all phi results in this
213 * Then it adds the best values (at most n_regs) to the blocks start_workset.
214 * The phis among the remaining values get spilled: Introduce psudo-copies of
215 * their args to break interference and make it possible to spill them to the
219 block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
221 block_info_t *block_info;
222 be_next_use_t next_use;
224 ir_node *best_starter, *first;
228 int outer_loop_allowed;
231 /* Create the block info for this block. */
232 block_info = new_block_info(&env->obst, block);
233 n_cfgpreds = get_Block_n_cfgpreds(block);
235 /* no cfgpred -> no value active */
236 if(n_cfgpreds == 0) {
237 block_info->start_state = NULL;
241 /* for 1 pred only: simply take the the end-state of the pred */
242 if(n_cfgpreds == 1) {
243 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
244 block_info_t *pred_info;
246 /* process pred block */
247 belady(env, pred_block);
249 pred_info = get_block_info(pred_block);
251 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
252 block_info->start_state = pred_info->end_state;
256 /* Collect all values living at start of block */
257 DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
258 first = sched_first(block);
259 loop = get_irn_loop(block);
261 best_time = USES_INFINITY;
262 outer_loop_allowed = 1;
264 /* check all Phis first */
265 sched_foreach(block, node) {
268 if (arch_get_irn_register(node) != env->reg)
271 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
272 next_use = be_get_next_use(env->uses, first, 0, node, 0);
274 if(USES_IS_INFINITE(next_use.time)) {
275 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
279 if(next_use.outermost_loop >= get_loop_depth(loop)) {
280 if(outer_loop_allowed || next_use.time < best_time) {
281 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
282 next_use.outermost_loop));
284 if(best_starter != NULL) {
285 /* spill the phi as it is not used */
286 spill_phi(env, best_starter);
289 best_time = next_use.time;
290 outer_loop_allowed = 0;
293 if(outer_loop_allowed && next_use.time < best_time) {
294 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
295 next_use.outermost_loop));
296 if(best_starter != NULL) {
297 /* spill the phi as it is not used */
298 spill_phi(env, best_starter);
301 best_time = next_use.time;
305 if(best_starter != node) {
306 /* spill the phi as it is not used */
307 spill_phi(env, best_starter);
311 /* check all Live-Ins */
312 be_lv_foreach(env->lv, block, be_lv_state_in, i) {
313 node = be_lv_get_irn(env->lv, block, i);
315 if(!mode_is_data(get_irn_mode(node)))
318 if (arch_get_irn_register(node) != env->reg)
321 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
322 next_use = be_get_next_use(env->uses, first, 0, node, 0);
324 if(USES_IS_INFINITE(next_use.time)) {
325 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
329 if(next_use.outermost_loop >= get_loop_depth(loop)) {
330 if(outer_loop_allowed || next_use.time < best_time) {
331 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
332 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;
340 outer_loop_allowed = 0;
343 if(outer_loop_allowed && next_use.time < best_time) {
344 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
345 next_use.outermost_loop));
346 if(best_starter != NULL && is_Phi(best_starter)) {
347 /* spill the phi as it is not used */
348 spill_phi(env, best_starter);
351 best_time = next_use.time;
356 block_info->start_state = best_starter;
362 * For the given block @p block, decide for each values
363 * whether it is used from a register or is reloaded
367 void belady(minibelady_env_t *env, ir_node *block)
369 ir_node *current_state;
371 block_info_t *block_info;
373 /* Don't do a block twice */
374 if(irn_visited(block))
377 /* compute value to start with */
378 block_info = compute_block_start_state(env, block);
380 /* get the starting workset for this block */
381 DBG((dbg, LEVEL_3, "\n"));
382 DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
384 current_state = block_info->start_state;
385 DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
387 /* process the block from start to end */
388 DBG((dbg, LEVEL_3, "Processing...\n"));
390 sched_foreach(block, node) {
392 ir_node *need_val = NULL;
394 /* projs are handled with the tuple value.
395 * Phis are no real instr (see insert_starters()) */
396 if (is_Proj(node) || is_Phi(node)) {
400 /* check which state is desired for the node */
401 arity = get_irn_arity(node);
402 for(i = 0; i < arity; ++i) {
403 const arch_register_t *reg;
404 ir_node *in = get_irn_n(node, i);
406 if(!mode_is_data(get_irn_mode(in)))
409 reg = arch_get_irn_register(in);
410 if(reg == env->reg) {
411 assert(need_val == NULL);
413 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
416 /* create a reload to match state if necessary */
417 if(need_val != NULL && need_val != current_state) {
418 DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
419 create_reload(env, need_val, node, current_state);
420 current_state = need_val;
423 DBG((dbg, LEVEL_3, " ...%+F\n", node));
425 /* record state changes by the node */
426 if (get_irn_mode(node) == mode_T) {
427 const ir_edge_t *edge;
429 foreach_out_edge(node, edge) {
430 const arch_register_t *reg;
431 ir_node *proj = get_edge_src_irn(edge);
433 if(!mode_is_data(get_irn_mode(proj)))
436 reg = arch_get_irn_register(proj);
437 if(reg == env->reg) {
438 current_state = proj;
439 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
443 if(mode_is_data(get_irn_mode(node))) {
444 const arch_register_t *reg = arch_get_irn_register(node);
445 if(reg == env->reg) {
446 current_state = node;
447 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
453 /* Remember end-workset for this block */
454 block_info->end_state = current_state;
455 DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
459 void belady_walker(ir_node *block, void *data)
461 belady((minibelady_env_t*) data, block);
465 ir_node *get_end_of_block_insertion_point(ir_node *block)
467 ir_node *last = sched_last(block);
469 /* skip Projs and Keep-alikes behind the jump... */
470 while(is_Proj(last) || be_is_Keep(last)) {
471 last = sched_prev(last);
475 last = sched_next(last);
476 /* last node must be a cfop, only exception is the start block */
477 assert(last == get_irg_start_block(get_irn_irg(block)));
484 * We must adapt the live-outs to the live-ins at each block-border.
487 void fix_block_borders(ir_node *block, void *data) {
488 minibelady_env_t *env = data;
489 ir_graph *irg = get_irn_irg(block);
490 ir_node *startblock = get_irg_start_block(irg);
493 block_info_t *block_info;
495 if(block == startblock)
498 DBG((dbg, LEVEL_3, "\n"));
500 block_info = get_block_info(block);
502 DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
503 block_info->start_state));
505 /* process all pred blocks */
506 arity = get_irn_arity(block);
507 for (i = 0; i < arity; ++i) {
508 ir_node *pred = get_Block_cfgpred_block(block, i);
509 block_info_t *pred_info = get_block_info(pred);
510 ir_node *need_state = block_info->start_state;
512 if(need_state == NULL)
515 if(is_Phi(need_state) && get_nodes_block(need_state) == block) {
516 need_state = get_irn_n(need_state, i);
519 DBG((dbg, LEVEL_3, " Pred %+F (ends in %+F, we need %+F)\n", pred,
520 pred_info->end_state, need_state));
522 if(pred_info->end_state != need_state) {
523 ir_node *insert_point = get_end_of_block_insertion_point(pred);
526 DBG((dbg, LEVEL_3, " Creating reload for %+F\n", need_state));
527 create_reload(env, need_state, insert_point, pred_info->end_state);
532 void be_assure_state(be_irg_t *birg, const arch_register_t *reg, void *func_env,
533 create_spill_func create_spill,
534 create_reload_func create_reload) {
535 minibelady_env_t env;
536 ir_graph *irg = be_get_birg_irg(birg);
538 be_lv_t *lv = be_assure_liveness(birg);
540 be_liveness_assure_sets(lv);
541 /* construct control flow loop tree */
542 if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
543 construct_cf_backedges(irg);
546 obstack_init(&env.obst);
548 env.func_env = func_env;
549 env.create_spill = create_spill;
550 env.create_reload = create_reload;
551 env.lv = be_get_birg_liveness(birg);
552 env.uses = be_begin_uses(irg, env.lv);
554 ir_nodemap_init(&env.spill_infos);
557 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
558 inc_irg_visited(irg);
561 irg_block_walk_graph(irg, NULL, belady_walker, &env);
563 /* fix block end_states that don't match the next blocks start_state */
564 irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
566 ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
568 /* reconstruct ssa-form */
570 while(info != NULL) {
571 be_ssa_construction_env_t senv;
575 be_ssa_construction_init(&senv, birg);
576 if(sched_is_scheduled(info->value))
577 be_ssa_construction_add_copy(&senv, info->value);
578 be_ssa_construction_add_copies(&senv,
579 info->reloads, ARR_LEN(info->reloads));
580 be_ssa_construction_fix_users(&senv, info->value);
583 be_ssa_construction_update_liveness_phis(&senv, lv);
585 be_liveness_update(lv, info->value);
586 len = ARR_LEN(info->reloads);
587 for(i = 0; i < len; ++i) {
588 ir_node *reload = info->reloads[i];
589 be_liveness_update(lv, reload);
593 phis = be_ssa_construction_get_new_phis(&senv);
595 /* set register requirements for phis */
597 for(i = 0; i < len; ++i) {
598 ir_node *phi = phis[i];
599 be_set_phi_flags(phi, arch_irn_flags_ignore);
600 arch_set_irn_register(phi, env.reg);
602 be_ssa_construction_destroy(&senv);
607 /* some nodes might be dead now. */
608 be_remove_dead_nodes_from_schedule(birg);
610 ir_nodemap_destroy(&env.spill_infos);
611 be_end_uses(env.uses);
612 obstack_free(&env.obst, NULL);
615 void be_init_state(void)
617 FIRM_DBG_REGISTER(dbg, "firm.be.state");
620 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);