nsz Git - libfirm/blob - ir/be/bestate.c

   1 /*
   2  * Copyright (C) 1995-2011 University of Karlsruhe.  All right reserved.
   3  *
   4  * This file is part of libFirm.
   5  *
   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.
  10  *
  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.
  14  *
  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
  17  * PURPOSE.
  18  */
  19
  20 /**
  21  * @file
  22  * @brief       Handles state switching. This is basically the belady spill
  23  *              algorithm optimized for the 1-register case.
  24  * @author      Matthias Braun
  25  * @date        26.03.2007
  26  */
  27 #include "config.h"
  28
  29 #include "bestate.h"
  30
  31 #include "obst.h"
  32 #include "irgraph_t.h"
  33 #include "irnode_t.h"
  34 #include "irgwalk.h"
  35 #include "irloop.h"
  36 #include "iredges_t.h"
  37 #include "ircons_t.h"
  38 #include "irgmod.h"
  39 #include "irnodeset.h"
  40 #include "irnodehashmap.h"
  41 #include "cpset.h"
  42
  43 #include "bearch.h"
  44 #include "beirg.h"
  45 #include "beuses.h"
  46 #include "besched.h"
  47 #include "belive_t.h"
  48 #include "bemodule.h"
  49 #include "benode.h"
  50 #include "beirgmod.h"
  51 #include "bespillutil.h"
  52 #include "bessaconstr.h"
  53
  54 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  55
  56 typedef struct spill_info_t {
  57         struct spill_info_t *next;
  58         ir_node *value;
  59         ir_node *spill;
  60         ir_node **reloads;
  61 } spill_info_t;
  62
  63 typedef struct minibelady_env_t {
  64         struct obstack         obst;
  65         const arch_register_t *reg;
  66         const be_lv_t         *lv;
  67         void                  *func_env;
  68         create_reload_func     create_reload;
  69         create_spill_func      create_spill;
  70         spill_info_t          *spills;
  71         ir_nodehashmap_t       spill_infos;
  72
  73         be_uses_t             *uses;           /**< env for the next-use magic */
  74 } minibelady_env_t;
  75
  76 typedef struct block_info_t {
  77         ir_node *start_state;
  78         ir_node *end_state;
  79 } block_info_t;
  80
  81 static inline block_info_t *new_block_info(struct obstack *obst, ir_node *block)
  82 {
  83         block_info_t *res = OALLOCZ(obst, block_info_t);
  84
  85         assert(is_Block(block));
  86         set_irn_link(block, res);
  87         mark_irn_visited(block);
  88
  89         return res;
  90 }
  91
  92 static inline block_info_t *get_block_info(ir_node *block)
  93 {
  94         assert(irn_visited(block));
  95         return (block_info_t*) get_irn_link(block);
  96 }
  97
  98 static inline spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
  99 {
 100         spill_info_t *spill_info = OALLOCZ(&env->obst, spill_info_t);
 101         spill_info->value = state;
 102         spill_info->reloads = NEW_ARR_F(ir_node*, 0);
 103
 104         ir_nodehashmap_insert(&env->spill_infos, state, spill_info);
 105         //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
 106
 107         spill_info->next = env->spills;
 108         env->spills = spill_info;
 109
 110         return spill_info;
 111 }
 112
 113 static inline spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
 114 {
 115         spill_info_t *spill_info = ir_nodehashmap_get(spill_info_t, &env->spill_infos, node);
 116         //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
 117         return spill_info;
 118 }
 119
 120 static spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
 121 {
 122         spill_info_t *spill_info;
 123         ir_node *next;
 124         ir_node *after;
 125
 126         spill_info = get_spill_info(env, state);
 127         if (spill_info == NULL) {
 128                 spill_info = create_spill_info(env, state);
 129         } else if (spill_info->spill != NULL) {
 130                 return spill_info;
 131         }
 132
 133         if (sched_is_scheduled(state)) {
 134                 next = state;
 135                 do {
 136                         after = next;
 137                         next = sched_next(after);
 138                 } while (is_Phi(next) || be_is_Keep(next));
 139         } else {
 140                 after = state;
 141         }
 142         spill_info->spill = env->create_spill(env->func_env, state, force, after);
 143
 144         return spill_info;
 145 }
 146
 147 static void create_reload(minibelady_env_t *env, ir_node *state,
 148                           ir_node *before, ir_node *last_state)
 149 {
 150         spill_info_t *spill_info = create_spill(env, state, 0);
 151         ir_node *spill = spill_info->spill;
 152         ir_node *reload;
 153
 154         reload = env->create_reload(env->func_env, state, spill, before,
 155                                     last_state);
 156         ARR_APP1(ir_node*, spill_info->reloads, reload);
 157 }
 158
 159 static void spill_phi(minibelady_env_t *env, ir_node *phi)
 160 {
 161         ir_graph     *irg           = get_irn_irg(phi);
 162         ir_node      *block         = get_nodes_block(phi);
 163         int           arity         = get_irn_arity(phi);
 164         ir_node     **phi_in        = ALLOCAN(ir_node*, arity);
 165         ir_node      *dummy         = new_r_Dummy(irg, mode_M);
 166         ir_node      *spill_to_kill = NULL;
 167         spill_info_t *spill_info;
 168         int           i;
 169
 170         /* does a spill exist for the phis value? */
 171         spill_info = get_spill_info(env, phi);
 172         if (spill_info != NULL) {
 173                 spill_to_kill = spill_info->spill;
 174         } else {
 175                 spill_info = create_spill_info(env, phi);
 176         }
 177
 178         /* create a new phi-M with bad preds */
 179         for (i = 0; i < arity; ++i) {
 180                 phi_in[i] = dummy;
 181         }
 182
 183         DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
 184
 185         /* create a Phi-M */
 186         spill_info->spill = be_new_Phi(block, arity, phi_in, mode_M,
 187                                        arch_no_register_req);
 188         sched_add_after(block, spill_info->spill);
 189
 190         if (spill_to_kill != NULL) {
 191                 exchange(spill_to_kill, spill_info->spill);
 192                 sched_remove(spill_to_kill);
 193         }
 194
 195         /* create spills for the phi values */
 196         for (i = 0; i < arity; ++i) {
 197                 ir_node *in = get_irn_n(phi, i);
 198                 spill_info_t *pred_spill = create_spill(env, in, 1);
 199                 set_irn_n(spill_info->spill, i, pred_spill->spill);
 200         }
 201 }
 202
 203 static void belady(minibelady_env_t *env, ir_node *block);
 204
 205 /**
 206  * Collects all values live-in at block @p block and all phi results in this
 207  * block.
 208  * Then it adds the best values (at most n_regs) to the blocks start_workset.
 209  * The phis among the remaining values get spilled: Introduce pseudo-copies of
 210  * their args to break interference and make it possible to spill them to the
 211  * same spill slot.
 212  */
 213 static block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
 214 {
 215         block_info_t  *block_info;
 216         be_next_use_t  next_use;
 217         ir_loop       *loop;
 218         ir_node       *best_starter, *first;
 219         int            n_cfgpreds;
 220         unsigned       best_time;
 221         int            outer_loop_allowed;
 222
 223         /* Create the block info for this block. */
 224         block_info = new_block_info(&env->obst, block);
 225         n_cfgpreds = get_Block_n_cfgpreds(block);
 226
 227         /* no cfgpred -> no value active */
 228         if (n_cfgpreds == 0) {
 229                 block_info->start_state = NULL;
 230                 return block_info;
 231         }
 232
 233         /* for 1 pred only: simply take the the end-state of the pred */
 234         if (n_cfgpreds == 1) {
 235                 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
 236                 block_info_t *pred_info;
 237
 238                 /* process pred block */
 239                 belady(env, pred_block);
 240
 241                 pred_info = get_block_info(pred_block);
 242
 243                 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
 244                 block_info->start_state = pred_info->end_state;
 245                 return block_info;
 246         }
 247
 248         /* Collect all values living at start of block */
 249         DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
 250         first = sched_first(block);
 251         loop = get_irn_loop(block);
 252         best_starter = NULL;
 253         best_time = USES_INFINITY;
 254         outer_loop_allowed = 1;
 255
 256         /* check all Phis first */
 257         sched_foreach(block, node) {
 258                 if (!is_Phi(node))
 259                         break;
 260                 if (arch_get_irn_register(node) != env->reg)
 261                         continue;
 262
 263                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 264                 next_use = be_get_next_use(env->uses, first, node, 0);
 265
 266                 if (USES_IS_INFINITE(next_use.time)) {
 267                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 268                         continue;
 269                 }
 270
 271                 if (next_use.outermost_loop >= get_loop_depth(loop)) {
 272                         if (outer_loop_allowed || next_use.time < best_time) {
 273                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 274                                      next_use.outermost_loop));
 275
 276                                 if (best_starter != NULL) {
 277                                         /* spill the phi as it is not used */
 278                                         spill_phi(env, best_starter);
 279                                 }
 280                                 best_starter = node;
 281                                 best_time = next_use.time;
 282                                 outer_loop_allowed = 0;
 283                         }
 284                 } else {
 285                         if (outer_loop_allowed && next_use.time < best_time) {
 286                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 287                                      next_use.outermost_loop));
 288                                 if (best_starter != NULL) {
 289                                         /* spill the phi as it is not used */
 290                                         spill_phi(env, best_starter);
 291                                 }
 292                                 best_starter = node;
 293                                 best_time = next_use.time;
 294                         }
 295                 }
 296
 297                 if (best_starter != node) {
 298                         /* spill the phi as it is not used */
 299                         spill_phi(env, best_starter);
 300                 }
 301         }
 302
 303         /* check all Live-Ins */
 304         be_lv_foreach_cls(env->lv, block, be_lv_state_in, env->reg->reg_class, node) {
 305                 if (arch_get_irn_register(node) != env->reg)
 306                         continue;
 307
 308                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 309                 next_use = be_get_next_use(env->uses, first, node, 0);
 310
 311                 if (USES_IS_INFINITE(next_use.time)) {
 312                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 313                         continue;
 314                 }
 315
 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));
 320
 321                                 if (best_starter != NULL && is_Phi(best_starter)) {
 322                                         /* spill the phi as it is not used */
 323                                         spill_phi(env, best_starter);
 324                                 }
 325                                 best_starter = node;
 326                                 best_time = next_use.time;
 327                                 outer_loop_allowed = 0;
 328                         }
 329                 } else {
 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);
 336                                 }
 337                                 best_starter = node;
 338                                 best_time = next_use.time;
 339                         }
 340                 }
 341         }
 342
 343         block_info->start_state = best_starter;
 344
 345         return block_info;
 346 }
 347
 348 /**
 349  * For the given block @p block, decide for each values
 350  * whether it is used from a register or is reloaded
 351  * before the use.
 352  */
 353 static void belady(minibelady_env_t *env, ir_node *block)
 354 {
 355         ir_node *current_state;
 356         block_info_t *block_info;
 357
 358         /* Don't do a block twice */
 359         if (irn_visited(block))
 360                 return;
 361
 362         /* compute value to start with */
 363         block_info = compute_block_start_state(env, block);
 364
 365         /* get the starting workset for this block */
 366         DBG((dbg, LEVEL_3, "\n"));
 367         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 368
 369         current_state = block_info->start_state;
 370         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 371
 372         /* process the block from start to end */
 373         DBG((dbg, LEVEL_3, "Processing...\n"));
 374
 375         sched_foreach(block, node) {
 376                 int i, arity;
 377                 ir_node *need_val = NULL;
 378
 379                 /* Phis are no real instr (see insert_starters()) */
 380                 if (is_Phi(node))
 381                         continue;
 382
 383                 /* check which state is desired for the node */
 384                 arity = get_irn_arity(node);
 385                 for (i = 0; i < arity; ++i) {
 386                         const arch_register_t *reg;
 387                         ir_node *in = get_irn_n(node, i);
 388
 389                         if (!mode_is_data(get_irn_mode(in)))
 390                                 continue;
 391
 392                         reg = arch_get_irn_register(in);
 393                         if (reg == env->reg) {
 394                                 assert(need_val == NULL);
 395                                 need_val = in;
 396                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 397                         }
 398                 }
 399                 /* create a reload to match state if necessary */
 400                 if (need_val != NULL && need_val != current_state) {
 401                         ir_node *before = node;
 402                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 403                         create_reload(env, need_val, before, current_state);
 404                         current_state = need_val;
 405                 }
 406
 407                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 408
 409                 /* record state changes by the node */
 410                 be_foreach_value(node, value,
 411                         if (!mode_is_data(get_irn_mode(value)))
 412                                 continue;
 413                         arch_register_t const *const reg = arch_get_irn_register(value);
 414                         if (reg != env->reg)
 415                                 continue;
 416                         current_state = value;
 417                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 418                 );
 419         }
 420
 421         /* Remember end-workset for this block */
 422         block_info->end_state = current_state;
 423         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 424 }
 425
 426 static void belady_walker(ir_node *block, void *data)
 427 {
 428         belady((minibelady_env_t*) data, block);
 429 }
 430
 431 /**
 432  * We must adapt the live-outs to the live-ins at each block-border.
 433  */
 434 static void fix_block_borders(ir_node *block, void *data)
 435 {
 436         minibelady_env_t *env = (minibelady_env_t*)data;
 437         int i;
 438         int arity;
 439         block_info_t *block_info;
 440
 441         DBG((dbg, LEVEL_3, "\n"));
 442
 443         block_info = get_block_info(block);
 444
 445         DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
 446              block_info->start_state));
 447
 448         /* process all pred blocks */
 449         arity = get_irn_arity(block);
 450         for (i = 0; i < arity; ++i) {
 451                 ir_node      *pred       = get_Block_cfgpred_block(block, i);
 452                 block_info_t *pred_info  = get_block_info(pred);
 453                 ir_node      *need_state = block_info->start_state;
 454
 455                 if (need_state == NULL)
 456                         continue;
 457
 458                 if (is_Phi(need_state) && get_nodes_block(need_state) == block) {
 459                         need_state = get_irn_n(need_state, i);
 460                 }
 461
 462                 DBG((dbg, LEVEL_3, "  Pred %+F (ends in %+F, we need %+F)\n", pred,
 463                      pred_info->end_state, need_state));
 464
 465                 if (pred_info->end_state != need_state) {
 466                         DBG((dbg, LEVEL_3, "  Creating reload for %+F\n", need_state));
 467                         ir_node *const insert_point = be_get_end_of_block_insertion_point(pred);
 468                         create_reload(env, need_state, insert_point, pred_info->end_state);
 469                 }
 470         }
 471 }
 472
 473 void be_assure_state(ir_graph *irg, const arch_register_t *reg, void *func_env,
 474                      create_spill_func create_spill,
 475                      create_reload_func create_reload)
 476 {
 477         minibelady_env_t env;
 478         spill_info_t *info;
 479         be_lv_t *lv = be_get_irg_liveness(irg);
 480
 481         be_assure_live_sets(irg);
 482         assure_loopinfo(irg);
 483
 484         obstack_init(&env.obst);
 485         env.reg           = reg;
 486         env.func_env      = func_env;
 487         env.create_spill  = create_spill;
 488         env.create_reload = create_reload;
 489         env.lv            = be_get_irg_liveness(irg);
 490         env.uses          = be_begin_uses(irg, env.lv);
 491         env.spills        = NULL;
 492         ir_nodehashmap_init(&env.spill_infos);
 493
 494         assure_doms(irg);
 495         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 496         inc_irg_visited(irg);
 497
 498         /* process blocks */
 499         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 500
 501         /* fix block end_states that don't match the next blocks start_state */
 502         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 503
 504         ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 505
 506         /* reconstruct ssa-form */
 507         info = env.spills;
 508         while (info != NULL) {
 509                 be_ssa_construction_env_t senv;
 510                 size_t i, len;
 511                 ir_node **phis;
 512
 513                 be_ssa_construction_init(&senv, irg);
 514                 if (sched_is_scheduled(info->value))
 515                         be_ssa_construction_add_copy(&senv, info->value);
 516                 be_ssa_construction_add_copies(&senv,
 517                                                info->reloads, ARR_LEN(info->reloads));
 518                 be_ssa_construction_fix_users(&senv, info->value);
 519
 520                 if (lv != NULL) {
 521                         be_ssa_construction_update_liveness_phis(&senv, lv);
 522
 523                         be_liveness_update(lv, info->value);
 524                         len = ARR_LEN(info->reloads);
 525                         for (i = 0; i < len; ++i) {
 526                                 ir_node *reload = info->reloads[i];
 527                                 be_liveness_update(lv, reload);
 528                         }
 529                 }
 530
 531                 phis = be_ssa_construction_get_new_phis(&senv);
 532
 533                 /* set register requirements for phis */
 534                 len = ARR_LEN(phis);
 535                 for (i = 0; i < len; ++i) {
 536                         ir_node *phi = phis[i];
 537                         arch_set_irn_register(phi, env.reg);
 538                 }
 539                 be_ssa_construction_destroy(&senv);
 540
 541                 info = info->next;
 542         }
 543
 544         /* some nodes might be dead now. */
 545         be_remove_dead_nodes_from_schedule(irg);
 546
 547         ir_nodehashmap_destroy(&env.spill_infos);
 548         be_end_uses(env.uses);
 549         obstack_free(&env.obst, NULL);
 550 }
 551
 552 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state)
 553 void be_init_state(void)
 554 {
 555         FIRM_DBG_REGISTER(dbg, "firm.be.state");
 556 }