2 * Copyright (C) 1995-2007 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
35 #include "irgraph_t.h"
39 #include "iredges_t.h"
45 #include "besched_t.h"
49 #include "bessaconstr.h"
51 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
53 typedef struct spill_info_t {
54 struct spill_info_t *next;
60 typedef struct minibelady_env_t {
62 const arch_env_t *arch_env;
63 const arch_register_t *reg;
66 create_reload_func create_reload;
67 create_spill_func create_spill;
70 be_uses_t *uses; /**< env for the next-use magic */
73 typedef struct block_info_t {
79 block_info_t *new_block_info(struct obstack *obst, ir_node *block)
81 block_info_t *res = obstack_alloc(obst, sizeof(*res));
82 memset(res, 0, sizeof(res[0]));
84 set_irn_link(block, res);
85 mark_irn_visited(block);
91 block_info_t *get_block_info(ir_node *block)
93 assert(irn_visited(block));
94 return (block_info_t*) get_irn_link(block);
98 spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
100 spill_info_t *spill_info = obstack_alloc(&env->obst, sizeof(spill_info[0]));
101 memset(spill_info, 0, sizeof(spill_info[0]));
102 spill_info->value = state;
103 spill_info->reloads = NEW_ARR_F(ir_node*, 0);
105 set_irn_link(state, spill_info);
106 mark_irn_visited(state);
108 spill_info->next = env->spills;
109 env->spills = spill_info;
115 spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
117 spill_info_t *spill_info;
121 if(irn_visited(state)) {
122 spill_info = (spill_info_t*) get_irn_link(state);
123 if(spill_info->spill != NULL || !force)
126 spill_info = create_spill_info(env, state);
129 if(sched_is_scheduled(state)) {
133 next = sched_next(after);
134 } while(is_Proj(next) || is_Phi(next) || be_is_Keep(next));
138 spill_info->spill = env->create_spill(env->func_env, state, force, after);
144 void create_reload(minibelady_env_t *env, ir_node *state, ir_node *before,
147 spill_info_t *spill_info = create_spill(env, state, 0);
148 ir_node *spill = spill_info->spill;
151 reload = env->create_reload(env->func_env, state, spill, before,
153 ARR_APP1(ir_node*, spill_info->reloads, reload);
157 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 i, arity = get_irn_arity(phi);
162 ir_node **in = alloca(arity * sizeof(in[0]));
163 ir_node *spill_to_kill = NULL;
164 spill_info_t *spill_info;
166 /* does a spill exist for the phis value? */
167 if(irn_visited(phi)) {
168 spill_info = (spill_info_t*) get_irn_link(phi);
169 spill_to_kill = spill_info->spill;
171 spill_info = create_spill_info(env, phi);
174 /* create a new phi-M with bad preds */
175 for(i = 0; i < arity; ++i) {
176 in[i] = new_r_Bad(irg);
179 DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
182 spill_info->spill = new_r_Phi(irg, block, arity, in, mode_M);
184 if(spill_to_kill != NULL) {
185 exchange(spill_to_kill, spill_info->spill);
186 sched_remove(spill_to_kill);
189 /* create spills for the phi values */
190 for(i = 0; i < arity; ++i) {
191 ir_node *in = get_irn_n(phi, i);
192 spill_info_t *pred_spill = create_spill(env, in, 1);
193 set_irn_n(spill_info->spill, i, pred_spill->spill);
198 void belady(minibelady_env_t *env, ir_node *block);
201 * Collects all values live-in at block @p block and all phi results in this
203 * Then it adds the best values (at most n_regs) to the blocks start_workset.
204 * The phis among the remaining values get spilled: Introduce psudo-copies of
205 * their args to break interference and make it possible to spill them to the
209 block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
211 block_info_t *block_info;
212 be_next_use_t next_use;
214 ir_node *best_starter, *first;
218 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(env->arch_env, node) != env->reg)
261 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
262 next_use = be_get_next_use(env->uses, first, 0, 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, i) {
303 node = be_lv_get_irn(env->lv, block, i);
305 if (arch_get_irn_register(env->arch_env, node) != env->reg)
308 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
309 next_use = be_get_next_use(env->uses, first, 0, node, 0);
311 if(USES_IS_INFINITE(next_use.time)) {
312 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
316 if(next_use.outermost_loop >= get_loop_depth(loop)) {
317 if(outer_loop_allowed || next_use.time < best_time) {
318 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
319 next_use.outermost_loop));
321 if(best_starter != NULL && is_Phi(best_starter)) {
322 /* spill the phi as it is not used */
323 spill_phi(env, best_starter);
326 best_time = next_use.time;
327 outer_loop_allowed = 0;
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));
333 if(best_starter != NULL && is_Phi(best_starter)) {
334 /* spill the phi as it is not used */
335 spill_phi(env, best_starter);
338 best_time = next_use.time;
343 block_info->start_state = best_starter;
349 * For the given block @p block, decide for each values
350 * whether it is used from a register or is reloaded
354 void belady(minibelady_env_t *env, ir_node *block)
356 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 ir_node *in = get_irn_n(node, i);
391 const arch_register_t *reg =
392 arch_get_irn_register(env->arch_env, in);
393 if(reg == env->reg) {
394 assert(need_val == NULL);
396 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
399 /* create a reload to match state if necessary */
400 if(need_val != NULL && need_val != current_state) {
401 DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
402 create_reload(env, need_val, node, current_state);
403 current_state = need_val;
406 DBG((dbg, LEVEL_3, " ...%+F\n", node));
408 /* record state changes by the node */
409 if (get_irn_mode(node) == mode_T) {
411 for(proj = sched_next(node); is_Proj(proj);
412 proj = sched_next(proj)) {
413 const arch_register_t *reg =
414 arch_get_irn_register(env->arch_env, proj);
415 if(reg == env->reg) {
416 current_state = proj;
417 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
421 const arch_register_t *reg =
422 arch_get_irn_register(env->arch_env, node);
423 if(reg == env->reg) {
424 current_state = node;
425 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
430 /* Remember end-workset for this block */
431 block_info->end_state = current_state;
432 DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
436 void belady_walker(ir_node *block, void *data)
438 belady((minibelady_env_t*) data, block);
442 ir_node *get_end_of_block_insertion_point(ir_node *block)
444 ir_node *last = sched_last(block);
446 /* skip projs and keepanies behind the jump... */
447 while(is_Proj(last) || be_is_Keep(last)) {
448 last = sched_prev(last);
452 last = sched_next(last);
453 // last node must be a cfop, only exception is the start block
454 assert(last == get_irg_start_block(get_irn_irg(block)));
461 * We must adapt the live-outs to the live-ins at each block-border.
464 void fix_block_borders(ir_node *block, void *data) {
465 minibelady_env_t *env = data;
466 ir_graph *irg = get_irn_irg(block);
467 ir_node *startblock = get_irg_start_block(irg);
470 block_info_t *block_info;
472 if(block == startblock)
475 DBG((dbg, LEVEL_3, "\n"));
476 DBG((dbg, LEVEL_3, "Fixing %+F\n", block));
478 block_info = get_block_info(block);
480 /* process all pred blocks */
481 arity = get_irn_arity(block);
482 for (i = 0; i < arity; ++i) {
483 ir_node *pred = get_Block_cfgpred_block(block, i);
484 block_info_t *pred_info = get_block_info(pred);
486 DBG((dbg, LEVEL_3, " Pred %+F\n", pred));
488 if(pred_info->end_state != block_info->start_state &&
489 block_info->start_state != NULL) {
490 ir_node *need_state = block_info->start_state;
491 ir_node *insert_point =
492 get_end_of_block_insertion_point(pred);
494 create_reload(env, need_state, insert_point, pred_info->end_state);
499 void be_assure_state(be_irg_t *birg, const arch_register_t *reg, void *func_env,
500 create_spill_func create_spill,
501 create_reload_func create_reload) {
502 minibelady_env_t env;
503 ir_graph *irg = be_get_birg_irg(birg);
505 be_lv_t *lv = be_get_birg_liveness(birg);
507 be_assure_liveness(birg);
508 be_assure_dom_front(birg);
509 /* construct control flow loop tree */
510 if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
511 construct_cf_backedges(irg);
514 obstack_init(&env.obst);
515 env.arch_env = be_get_birg_arch_env(birg);
517 env.func_env = func_env;
518 env.create_spill = create_spill;
519 env.create_reload = create_reload;
520 env.lv = be_get_birg_liveness(birg);
521 env.uses = be_begin_uses(irg, env.lv);
524 set_using_visited(irg);
525 set_using_irn_link(irg);
526 inc_irg_visited(irg);
529 irg_block_walk_graph(irg, NULL, belady_walker, &env);
531 /* fix block end_states that don't match the next blocks start_state */
532 irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
534 clear_using_visited(irg);
535 clear_using_irn_link(irg);
537 /* reconstruct ssa-form */
539 while(info != NULL) {
540 be_ssa_construction_env_t senv;
544 be_ssa_construction_init(&senv, birg);
545 if(sched_is_scheduled(info->value))
546 be_ssa_construction_add_copy(&senv, info->value);
547 be_ssa_construction_add_copies(&senv,
548 info->reloads, ARR_LEN(info->reloads));
549 be_ssa_construction_fix_users(&senv, info->value);
552 be_ssa_construction_update_liveness_phis(&senv, lv);
554 be_liveness_update(lv, info->value);
555 len = ARR_LEN(info->reloads);
556 for(i = 0; i < len; ++i) {
557 ir_node *reload = info->reloads[i];
558 be_liveness_update(lv, reload);
562 phis = be_ssa_construction_get_new_phis(&senv);
564 /* set register requirements for phis */
566 for(i = 0; i < len; ++i) {
567 ir_node *phi = phis[i];
568 be_set_phi_flags(env.arch_env, phi, arch_irn_flags_ignore);
569 arch_set_irn_register(env.arch_env, phi, env.reg);
571 be_ssa_construction_destroy(&senv);
576 /* some nodes might be dead now. */
577 be_remove_dead_nodes_from_schedule(irg);
579 be_end_uses(env.uses);
580 obstack_free(&env.obst, NULL);
583 void be_init_state(void)
585 FIRM_DBG_REGISTER(dbg, "firm.be.state");
588 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);