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"
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_nodehashmap_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_nodehashmap_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 = ir_nodehashmap_get(spill_info_t, &env->spill_infos, node);
115 //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
119 static spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
121 spill_info_t *spill_info;
125 spill_info = get_spill_info(env, state);
126 if (spill_info == NULL) {
127 spill_info = create_spill_info(env, state);
128 } else if (spill_info->spill != NULL) {
132 if (sched_is_scheduled(state)) {
136 next = sched_next(after);
137 } while (is_Proj(next) || is_Phi(next) || be_is_Keep(next));
141 spill_info->spill = env->create_spill(env->func_env, state, force, after);
146 static void create_reload(minibelady_env_t *env, ir_node *state,
147 ir_node *before, ir_node *last_state)
149 spill_info_t *spill_info = create_spill(env, state, 0);
150 ir_node *spill = spill_info->spill;
153 reload = env->create_reload(env->func_env, state, spill, before,
155 ARR_APP1(ir_node*, spill_info->reloads, reload);
158 static void spill_phi(minibelady_env_t *env, ir_node *phi)
160 ir_graph *irg = get_irn_irg(phi);
161 ir_node *block = get_nodes_block(phi);
162 int arity = get_irn_arity(phi);
163 ir_node **phi_in = ALLOCAN(ir_node*, arity);
164 ir_node *dummy = new_r_Dummy(irg, mode_M);
165 ir_node *spill_to_kill = NULL;
166 spill_info_t *spill_info;
169 /* does a spill exist for the phis value? */
170 spill_info = get_spill_info(env, phi);
171 if (spill_info != NULL) {
172 spill_to_kill = spill_info->spill;
174 spill_info = create_spill_info(env, phi);
177 /* create a new phi-M with bad preds */
178 for (i = 0; i < arity; ++i) {
182 DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
185 spill_info->spill = be_new_Phi(block, arity, phi_in, mode_M,
186 arch_no_register_req);
187 sched_add_after(block, spill_info->spill);
189 if (spill_to_kill != NULL) {
190 exchange(spill_to_kill, spill_info->spill);
191 sched_remove(spill_to_kill);
194 /* create spills for the phi values */
195 for (i = 0; i < arity; ++i) {
196 ir_node *in = get_irn_n(phi, i);
197 spill_info_t *pred_spill = create_spill(env, in, 1);
198 set_irn_n(spill_info->spill, i, pred_spill->spill);
202 static void belady(minibelady_env_t *env, ir_node *block);
205 * Collects all values live-in at block @p block and all phi results in this
207 * Then it adds the best values (at most n_regs) to the blocks start_workset.
208 * The phis among the remaining values get spilled: Introduce pseudo-copies of
209 * their args to break interference and make it possible to spill them to the
212 static block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
214 block_info_t *block_info;
215 be_next_use_t next_use;
217 ir_node *best_starter, *first;
220 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, node) {
304 if (!mode_is_data(get_irn_mode(node)))
307 if (arch_get_irn_register(node) != env->reg)
310 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
311 next_use = be_get_next_use(env->uses, first, node, 0);
313 if (USES_IS_INFINITE(next_use.time)) {
314 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
318 if (next_use.outermost_loop >= get_loop_depth(loop)) {
319 if (outer_loop_allowed || next_use.time < best_time) {
320 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
321 next_use.outermost_loop));
323 if (best_starter != NULL && is_Phi(best_starter)) {
324 /* spill the phi as it is not used */
325 spill_phi(env, best_starter);
328 best_time = next_use.time;
329 outer_loop_allowed = 0;
332 if (outer_loop_allowed && next_use.time < best_time) {
333 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
334 next_use.outermost_loop));
335 if (best_starter != NULL && is_Phi(best_starter)) {
336 /* spill the phi as it is not used */
337 spill_phi(env, best_starter);
340 best_time = next_use.time;
345 block_info->start_state = best_starter;
351 * For the given block @p block, decide for each values
352 * whether it is used from a register or is reloaded
355 static void belady(minibelady_env_t *env, ir_node *block)
357 ir_node *current_state;
358 block_info_t *block_info;
360 /* Don't do a block twice */
361 if (irn_visited(block))
364 /* compute value to start with */
365 block_info = compute_block_start_state(env, block);
367 /* get the starting workset for this block */
368 DBG((dbg, LEVEL_3, "\n"));
369 DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
371 current_state = block_info->start_state;
372 DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
374 /* process the block from start to end */
375 DBG((dbg, LEVEL_3, "Processing...\n"));
377 sched_foreach(block, node) {
379 ir_node *need_val = NULL;
381 /* projs are handled with the tuple value.
382 * Phis are no real instr (see insert_starters()) */
383 if (is_Proj(node) || is_Phi(node)) {
387 /* check which state is desired for the node */
388 arity = get_irn_arity(node);
389 for (i = 0; i < arity; ++i) {
390 const arch_register_t *reg;
391 ir_node *in = get_irn_n(node, i);
393 if (!mode_is_data(get_irn_mode(in)))
396 reg = arch_get_irn_register(in);
397 if (reg == env->reg) {
398 assert(need_val == NULL);
400 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
403 /* create a reload to match state if necessary */
404 if (need_val != NULL && need_val != current_state) {
405 ir_node *before = node;
406 DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
407 create_reload(env, need_val, before, current_state);
408 current_state = need_val;
411 DBG((dbg, LEVEL_3, " ...%+F\n", node));
413 /* record state changes by the node */
414 if (get_irn_mode(node) == mode_T) {
415 foreach_out_edge(node, edge) {
416 const arch_register_t *reg;
417 ir_node *proj = get_edge_src_irn(edge);
419 if (!mode_is_data(get_irn_mode(proj)))
422 reg = arch_get_irn_register(proj);
423 if (reg == env->reg) {
424 current_state = proj;
425 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
429 if (mode_is_data(get_irn_mode(node))) {
430 const arch_register_t *reg = arch_get_irn_register(node);
431 if (reg == env->reg) {
432 current_state = node;
433 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
439 /* Remember end-workset for this block */
440 block_info->end_state = current_state;
441 DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
444 static void belady_walker(ir_node *block, void *data)
446 belady((minibelady_env_t*) data, block);
449 static ir_node *get_end_of_block_insertion_point(ir_node *block)
451 ir_node *last = sched_last(block);
453 /* skip Projs and Keep-alikes behind the jump... */
454 while (is_Proj(last) || be_is_Keep(last)) {
455 last = sched_prev(last);
458 if (!is_cfop(last)) {
459 last = sched_next(last);
460 /* last node must be a cfop, only exception is the start block */
461 assert(last == get_irg_start_block(get_irn_irg(block)));
468 * We must adapt the live-outs to the live-ins at each block-border.
470 static void fix_block_borders(ir_node *block, void *data)
472 minibelady_env_t *env = (minibelady_env_t*)data;
473 ir_graph *irg = get_irn_irg(block);
474 ir_node *startblock = get_irg_start_block(irg);
477 block_info_t *block_info;
479 if (block == startblock)
482 DBG((dbg, LEVEL_3, "\n"));
484 block_info = get_block_info(block);
486 DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
487 block_info->start_state));
489 /* process all pred blocks */
490 arity = get_irn_arity(block);
491 for (i = 0; i < arity; ++i) {
492 ir_node *pred = get_Block_cfgpred_block(block, i);
493 block_info_t *pred_info = get_block_info(pred);
494 ir_node *need_state = block_info->start_state;
496 if (need_state == NULL)
499 if (is_Phi(need_state) && get_nodes_block(need_state) == block) {
500 need_state = get_irn_n(need_state, i);
503 DBG((dbg, LEVEL_3, " Pred %+F (ends in %+F, we need %+F)\n", pred,
504 pred_info->end_state, need_state));
506 if (pred_info->end_state != need_state) {
507 ir_node *insert_point = get_end_of_block_insertion_point(pred);
510 DBG((dbg, LEVEL_3, " Creating reload for %+F\n", need_state));
511 create_reload(env, need_state, insert_point, pred_info->end_state);
516 void be_assure_state(ir_graph *irg, const arch_register_t *reg, void *func_env,
517 create_spill_func create_spill,
518 create_reload_func create_reload)
520 minibelady_env_t env;
522 be_lv_t *lv = be_get_irg_liveness(irg);
524 be_assure_live_sets(irg);
525 assure_loopinfo(irg);
527 obstack_init(&env.obst);
529 env.func_env = func_env;
530 env.create_spill = create_spill;
531 env.create_reload = create_reload;
532 env.lv = be_get_irg_liveness(irg);
533 env.uses = be_begin_uses(irg, env.lv);
535 ir_nodehashmap_init(&env.spill_infos);
538 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
539 inc_irg_visited(irg);
542 irg_block_walk_graph(irg, NULL, belady_walker, &env);
544 /* fix block end_states that don't match the next blocks start_state */
545 irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
547 ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
549 /* reconstruct ssa-form */
551 while (info != NULL) {
552 be_ssa_construction_env_t senv;
556 be_ssa_construction_init(&senv, irg);
557 if (sched_is_scheduled(info->value))
558 be_ssa_construction_add_copy(&senv, info->value);
559 be_ssa_construction_add_copies(&senv,
560 info->reloads, ARR_LEN(info->reloads));
561 be_ssa_construction_fix_users(&senv, info->value);
564 be_ssa_construction_update_liveness_phis(&senv, lv);
566 be_liveness_update(lv, info->value);
567 len = ARR_LEN(info->reloads);
568 for (i = 0; i < len; ++i) {
569 ir_node *reload = info->reloads[i];
570 be_liveness_update(lv, reload);
574 phis = be_ssa_construction_get_new_phis(&senv);
576 /* set register requirements for phis */
578 for (i = 0; i < len; ++i) {
579 ir_node *phi = phis[i];
580 arch_set_irn_register(phi, env.reg);
582 be_ssa_construction_destroy(&senv);
587 /* some nodes might be dead now. */
588 be_remove_dead_nodes_from_schedule(irg);
590 ir_nodehashmap_destroy(&env.spill_infos);
591 be_end_uses(env.uses);
592 obstack_free(&env.obst, NULL);
595 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state)
596 void be_init_state(void)
598 FIRM_DBG_REGISTER(dbg, "firm.be.state");