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"
42 #include "irnodeset.h"
43 #include "irnodemap.h"
44 #include "adt/cpset.h"
48 #include "besched_t.h"
52 #include "bessaconstr.h"
54 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
56 typedef struct spill_info_t {
57 struct spill_info_t *next;
63 typedef struct minibelady_env_t {
65 const arch_env_t *arch_env;
66 const arch_register_t *reg;
69 create_reload_func create_reload;
70 create_spill_func create_spill;
72 ir_nodemap_t spill_infos;
74 be_uses_t *uses; /**< env for the next-use magic */
77 typedef struct block_info_t {
83 block_info_t *new_block_info(struct obstack *obst, ir_node *block)
85 block_info_t *res = obstack_alloc(obst, sizeof(*res));
86 memset(res, 0, sizeof(res[0]));
88 assert(is_Block(block));
89 set_irn_link(block, res);
90 mark_irn_visited(block);
96 block_info_t *get_block_info(ir_node *block)
98 assert(irn_visited(block));
99 return (block_info_t*) get_irn_link(block);
103 spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
105 spill_info_t *spill_info = obstack_alloc(&env->obst, sizeof(spill_info[0]));
106 memset(spill_info, 0, sizeof(spill_info[0]));
107 spill_info->value = state;
108 spill_info->reloads = NEW_ARR_F(ir_node*, 0);
110 ir_nodemap_insert(&env->spill_infos, state, spill_info);
111 //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
113 spill_info->next = env->spills;
114 env->spills = spill_info;
120 spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
122 spill_info_t *spill_info
123 = (spill_info_t*) ir_nodemap_get(&env->spill_infos, node);
124 //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
129 spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
131 spill_info_t *spill_info;
135 spill_info = get_spill_info(env, state);
136 if(spill_info == NULL) {
137 spill_info = create_spill_info(env, state);
140 if(sched_is_scheduled(state)) {
144 next = sched_next(after);
145 } while(is_Proj(next) || is_Phi(next) || be_is_Keep(next));
149 spill_info->spill = env->create_spill(env->func_env, state, force, after);
155 void create_reload(minibelady_env_t *env, ir_node *state, ir_node *before,
158 spill_info_t *spill_info = create_spill(env, state, 0);
159 ir_node *spill = spill_info->spill;
162 reload = env->create_reload(env->func_env, state, spill, before,
164 ARR_APP1(ir_node*, spill_info->reloads, reload);
168 void spill_phi(minibelady_env_t *env, ir_node *phi)
170 ir_graph *irg = get_irn_irg(phi);
171 ir_node *block = get_nodes_block(phi);
172 int i, arity = get_irn_arity(phi);
173 ir_node **in = alloca(arity * sizeof(in[0]));
174 ir_node *spill_to_kill = NULL;
175 spill_info_t *spill_info;
177 /* does a spill exist for the phis value? */
178 spill_info = get_spill_info(env, phi);
179 if(spill_info != NULL) {
180 spill_to_kill = spill_info->spill;
182 spill_info = create_spill_info(env, phi);
185 /* create a new phi-M with bad preds */
186 for(i = 0; i < arity; ++i) {
187 in[i] = new_r_Bad(irg);
190 DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
193 spill_info->spill = new_r_Phi(irg, block, arity, in, mode_M);
195 if(spill_to_kill != NULL) {
196 exchange(spill_to_kill, spill_info->spill);
197 sched_remove(spill_to_kill);
200 /* create spills for the phi values */
201 for(i = 0; i < arity; ++i) {
202 ir_node *in = get_irn_n(phi, i);
203 spill_info_t *pred_spill = create_spill(env, in, 1);
204 set_irn_n(spill_info->spill, i, pred_spill->spill);
209 void belady(minibelady_env_t *env, ir_node *block);
212 * Collects all values live-in at block @p block and all phi results in this
214 * Then it adds the best values (at most n_regs) to the blocks start_workset.
215 * The phis among the remaining values get spilled: Introduce psudo-copies of
216 * their args to break interference and make it possible to spill them to the
220 block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
222 block_info_t *block_info;
223 be_next_use_t next_use;
225 ir_node *best_starter, *first;
229 int outer_loop_allowed;
232 /* Create the block info for this block. */
233 block_info = new_block_info(&env->obst, block);
234 n_cfgpreds = get_Block_n_cfgpreds(block);
236 /* no cfgpred -> no value active */
237 if(n_cfgpreds == 0) {
238 block_info->start_state = NULL;
242 /* for 1 pred only: simply take the the end-state of the pred */
243 if(n_cfgpreds == 1) {
244 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
245 block_info_t *pred_info;
247 /* process pred block */
248 belady(env, pred_block);
250 pred_info = get_block_info(pred_block);
252 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
253 block_info->start_state = pred_info->end_state;
257 /* Collect all values living at start of block */
258 DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
259 first = sched_first(block);
260 loop = get_irn_loop(block);
262 best_time = USES_INFINITY;
263 outer_loop_allowed = 1;
265 /* check all Phis first */
266 sched_foreach(block, node) {
269 if (arch_get_irn_register(env->arch_env, node) != env->reg)
272 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
273 next_use = be_get_next_use(env->uses, first, 0, node, 0);
275 if(USES_IS_INFINITE(next_use.time)) {
276 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
280 if(next_use.outermost_loop >= get_loop_depth(loop)) {
281 if(outer_loop_allowed || next_use.time < best_time) {
282 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
283 next_use.outermost_loop));
285 if(best_starter != NULL) {
286 /* spill the phi as it is not used */
287 spill_phi(env, best_starter);
290 best_time = next_use.time;
291 outer_loop_allowed = 0;
294 if(outer_loop_allowed && next_use.time < best_time) {
295 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
296 next_use.outermost_loop));
297 if(best_starter != NULL) {
298 /* spill the phi as it is not used */
299 spill_phi(env, best_starter);
302 best_time = next_use.time;
306 if(best_starter != node) {
307 /* spill the phi as it is not used */
308 spill_phi(env, best_starter);
312 /* check all Live-Ins */
313 be_lv_foreach(env->lv, block, be_lv_state_in, i) {
314 node = be_lv_get_irn(env->lv, block, i);
316 if (arch_get_irn_register(env->arch_env, node) != env->reg)
319 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
320 next_use = be_get_next_use(env->uses, first, 0, node, 0);
322 if(USES_IS_INFINITE(next_use.time)) {
323 DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
327 if(next_use.outermost_loop >= get_loop_depth(loop)) {
328 if(outer_loop_allowed || next_use.time < best_time) {
329 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
330 next_use.outermost_loop));
332 if(best_starter != NULL && is_Phi(best_starter)) {
333 /* spill the phi as it is not used */
334 spill_phi(env, best_starter);
337 best_time = next_use.time;
338 outer_loop_allowed = 0;
341 if(outer_loop_allowed && next_use.time < best_time) {
342 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
343 next_use.outermost_loop));
344 if(best_starter != NULL && is_Phi(best_starter)) {
345 /* spill the phi as it is not used */
346 spill_phi(env, best_starter);
349 best_time = next_use.time;
354 block_info->start_state = best_starter;
360 * For the given block @p block, decide for each values
361 * whether it is used from a register or is reloaded
365 void belady(minibelady_env_t *env, ir_node *block)
367 ir_node *current_state;
369 block_info_t *block_info;
371 /* Don't do a block twice */
372 if(irn_visited(block))
375 /* compute value to start with */
376 block_info = compute_block_start_state(env, block);
378 /* get the starting workset for this block */
379 DBG((dbg, LEVEL_3, "\n"));
380 DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
382 current_state = block_info->start_state;
383 DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
385 /* process the block from start to end */
386 DBG((dbg, LEVEL_3, "Processing...\n"));
388 sched_foreach(block, node) {
390 ir_node *need_val = NULL;
392 /* projs are handled with the tuple value.
393 * Phis are no real instr (see insert_starters()) */
394 if (is_Proj(node) || is_Phi(node)) {
398 /* check which state is desired for the node */
399 arity = get_irn_arity(node);
400 for(i = 0; i < arity; ++i) {
401 ir_node *in = get_irn_n(node, i);
402 const arch_register_t *reg =
403 arch_get_irn_register(env->arch_env, in);
404 if(reg == env->reg) {
405 assert(need_val == NULL);
407 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
410 /* create a reload to match state if necessary */
411 if(need_val != NULL && need_val != current_state) {
412 DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
413 create_reload(env, need_val, node, current_state);
414 current_state = need_val;
417 DBG((dbg, LEVEL_3, " ...%+F\n", node));
419 /* record state changes by the node */
420 if (get_irn_mode(node) == mode_T) {
421 const ir_edge_t *edge;
423 foreach_out_edge(node, edge) {
424 ir_node *proj = get_edge_src_irn(edge);
425 const arch_register_t *reg =
426 arch_get_irn_register(env->arch_env, proj);
427 if(reg == env->reg) {
428 current_state = proj;
429 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
433 const arch_register_t *reg =
434 arch_get_irn_register(env->arch_env, node);
435 if(reg == env->reg) {
436 current_state = node;
437 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
442 /* Remember end-workset for this block */
443 block_info->end_state = current_state;
444 DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
448 void belady_walker(ir_node *block, void *data)
450 belady((minibelady_env_t*) data, block);
454 ir_node *get_end_of_block_insertion_point(ir_node *block)
456 ir_node *last = sched_last(block);
458 /* skip Projs and Keep-alikes behind the jump... */
459 while(is_Proj(last) || be_is_Keep(last)) {
460 last = sched_prev(last);
464 last = sched_next(last);
465 /* last node must be a cfop, only exception is the start block */
466 assert(last == get_irg_start_block(get_irn_irg(block)));
473 * We must adapt the live-outs to the live-ins at each block-border.
476 void fix_block_borders(ir_node *block, void *data) {
477 minibelady_env_t *env = data;
478 ir_graph *irg = get_irn_irg(block);
479 ir_node *startblock = get_irg_start_block(irg);
482 block_info_t *block_info;
484 if(block == startblock)
487 DBG((dbg, LEVEL_3, "\n"));
489 block_info = get_block_info(block);
491 DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
492 block_info->start_state));
494 /* process all pred blocks */
495 arity = get_irn_arity(block);
496 for (i = 0; i < arity; ++i) {
497 ir_node *pred = get_Block_cfgpred_block(block, i);
498 block_info_t *pred_info = get_block_info(pred);
499 ir_node *need_state = block_info->start_state;
501 if(need_state == NULL)
504 if(is_Phi(need_state) && get_nodes_block(need_state) == block) {
505 need_state = get_irn_n(need_state, i);
508 DBG((dbg, LEVEL_3, " Pred %+F (ends in %+F, we need %+F)\n", pred,
509 pred_info->end_state, need_state));
511 if(pred_info->end_state != need_state) {
512 ir_node *insert_point = get_end_of_block_insertion_point(pred);
515 DBG((dbg, LEVEL_3, " Creating reload for %+F\n", need_state));
516 create_reload(env, need_state, insert_point, pred_info->end_state);
521 void be_assure_state(be_irg_t *birg, const arch_register_t *reg, void *func_env,
522 create_spill_func create_spill,
523 create_reload_func create_reload) {
524 minibelady_env_t env;
525 ir_graph *irg = be_get_birg_irg(birg);
527 be_lv_t *lv = be_assure_liveness(birg);
529 be_liveness_assure_sets(lv);
530 be_assure_dom_front(birg);
531 /* construct control flow loop tree */
532 if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
533 construct_cf_backedges(irg);
536 obstack_init(&env.obst);
537 env.arch_env = be_get_birg_arch_env(birg);
539 env.func_env = func_env;
540 env.create_spill = create_spill;
541 env.create_reload = create_reload;
542 env.lv = be_get_birg_liveness(birg);
543 env.uses = be_begin_uses(irg, env.lv);
545 ir_nodemap_init(&env.spill_infos);
548 set_using_visited(irg);
549 set_using_irn_link(irg);
550 inc_irg_visited(irg);
553 irg_block_walk_graph(irg, NULL, belady_walker, &env);
555 /* fix block end_states that don't match the next blocks start_state */
556 irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
558 clear_using_visited(irg);
559 clear_using_irn_link(irg);
561 /* reconstruct ssa-form */
563 while(info != NULL) {
564 be_ssa_construction_env_t senv;
568 be_ssa_construction_init(&senv, birg);
569 if(sched_is_scheduled(info->value))
570 be_ssa_construction_add_copy(&senv, info->value);
571 be_ssa_construction_add_copies(&senv,
572 info->reloads, ARR_LEN(info->reloads));
573 be_ssa_construction_fix_users(&senv, info->value);
576 be_ssa_construction_update_liveness_phis(&senv, lv);
578 be_liveness_update(lv, info->value);
579 len = ARR_LEN(info->reloads);
580 for(i = 0; i < len; ++i) {
581 ir_node *reload = info->reloads[i];
582 be_liveness_update(lv, reload);
586 phis = be_ssa_construction_get_new_phis(&senv);
588 /* set register requirements for phis */
590 for(i = 0; i < len; ++i) {
591 ir_node *phi = phis[i];
592 be_set_phi_flags(env.arch_env, phi, arch_irn_flags_ignore);
593 arch_set_irn_register(env.arch_env, phi, env.reg);
595 be_ssa_construction_destroy(&senv);
600 /* some nodes might be dead now. */
601 be_remove_dead_nodes_from_schedule(birg);
603 ir_nodemap_destroy(&env.spill_infos);
604 be_end_uses(env.uses);
605 obstack_free(&env.obst, NULL);
608 void be_init_state(void)
610 FIRM_DBG_REGISTER(dbg, "firm.be.state");
613 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);