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

   1 /*
   2  * This file is part of libFirm.
   3  * Copyright (C) 2012 University of Karlsruhe.
   4  */
   5
   6 /**
   7  * @file
   8  * @brief       Handles state switching. This is basically the belady spill
   9  *              algorithm optimized for the 1-register case.
  10  * @author      Matthias Braun
  11  * @date        26.03.2007
  12  */
  13 #include "config.h"
  14
  15 #include "bestate.h"
  16
  17 #include "obst.h"
  18 #include "irgraph_t.h"
  19 #include "irnode_t.h"
  20 #include "irgwalk.h"
  21 #include "irloop.h"
  22 #include "iredges_t.h"
  23 #include "ircons_t.h"
  24 #include "irgmod.h"
  25 #include "irnodeset.h"
  26 #include "irnodehashmap.h"
  27 #include "cpset.h"
  28
  29 #include "bearch.h"
  30 #include "beirg.h"
  31 #include "beuses.h"
  32 #include "besched.h"
  33 #include "belive_t.h"
  34 #include "bemodule.h"
  35 #include "benode.h"
  36 #include "beirgmod.h"
  37 #include "bespillutil.h"
  38 #include "bessaconstr.h"
  39
  40 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  41
  42 typedef struct spill_info_t {
  43         struct spill_info_t *next;
  44         ir_node *value;
  45         ir_node *spill;
  46         ir_node **reloads;
  47 } spill_info_t;
  48
  49 typedef struct minibelady_env_t {
  50         struct obstack         obst;
  51         const arch_register_t *reg;
  52         const be_lv_t         *lv;
  53         void                  *func_env;
  54         create_reload_func     create_reload;
  55         create_spill_func      create_spill;
  56         spill_info_t          *spills;
  57         ir_nodehashmap_t       spill_infos;
  58
  59         be_uses_t             *uses;           /**< env for the next-use magic */
  60 } minibelady_env_t;
  61
  62 typedef struct block_info_t {
  63         ir_node *start_state;
  64         ir_node *end_state;
  65 } block_info_t;
  66
  67 static inline block_info_t *new_block_info(struct obstack *obst, ir_node *block)
  68 {
  69         block_info_t *res = OALLOCZ(obst, block_info_t);
  70
  71         assert(is_Block(block));
  72         set_irn_link(block, res);
  73         mark_irn_visited(block);
  74
  75         return res;
  76 }
  77
  78 static inline block_info_t *get_block_info(ir_node *block)
  79 {
  80         assert(irn_visited(block));
  81         return (block_info_t*) get_irn_link(block);
  82 }
  83
  84 static inline spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
  85 {
  86         spill_info_t *spill_info = OALLOCZ(&env->obst, spill_info_t);
  87         spill_info->value = state;
  88         spill_info->reloads = NEW_ARR_F(ir_node*, 0);
  89
  90         ir_nodehashmap_insert(&env->spill_infos, state, spill_info);
  91         //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
  92
  93         spill_info->next = env->spills;
  94         env->spills = spill_info;
  95
  96         return spill_info;
  97 }
  98
  99 static inline spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
 100 {
 101         spill_info_t *spill_info = ir_nodehashmap_get(spill_info_t, &env->spill_infos, node);
 102         //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
 103         return spill_info;
 104 }
 105
 106 static spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
 107 {
 108         spill_info_t *spill_info;
 109         ir_node *next;
 110         ir_node *after;
 111
 112         spill_info = get_spill_info(env, state);
 113         if (spill_info == NULL) {
 114                 spill_info = create_spill_info(env, state);
 115         } else if (spill_info->spill != NULL) {
 116                 return spill_info;
 117         }
 118
 119         if (sched_is_scheduled(state)) {
 120                 next = state;
 121                 do {
 122                         after = next;
 123                         next = sched_next(after);
 124                 } while (is_Phi(next) || be_is_Keep(next));
 125         } else {
 126                 after = state;
 127         }
 128         spill_info->spill = env->create_spill(env->func_env, state, force, after);
 129
 130         return spill_info;
 131 }
 132
 133 static void create_reload(minibelady_env_t *env, ir_node *state,
 134                           ir_node *before, ir_node *last_state)
 135 {
 136         spill_info_t *spill_info = create_spill(env, state, 0);
 137         ir_node *spill = spill_info->spill;
 138         ir_node *reload;
 139
 140         reload = env->create_reload(env->func_env, state, spill, before,
 141                                     last_state);
 142         ARR_APP1(ir_node*, spill_info->reloads, reload);
 143 }
 144
 145 static void spill_phi(minibelady_env_t *env, ir_node *phi)
 146 {
 147         ir_graph     *irg           = get_irn_irg(phi);
 148         ir_node      *block         = get_nodes_block(phi);
 149         int           arity         = get_irn_arity(phi);
 150         ir_node     **phi_in        = ALLOCAN(ir_node*, arity);
 151         ir_node      *dummy         = new_r_Dummy(irg, mode_M);
 152         ir_node      *spill_to_kill = NULL;
 153         spill_info_t *spill_info;
 154         int           i;
 155
 156         /* does a spill exist for the phis value? */
 157         spill_info = get_spill_info(env, phi);
 158         if (spill_info != NULL) {
 159                 spill_to_kill = spill_info->spill;
 160         } else {
 161                 spill_info = create_spill_info(env, phi);
 162         }
 163
 164         /* create a new phi-M with bad preds */
 165         for (i = 0; i < arity; ++i) {
 166                 phi_in[i] = dummy;
 167         }
 168
 169         DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
 170
 171         /* create a Phi-M */
 172         spill_info->spill = be_new_Phi(block, arity, phi_in, mode_M,
 173                                        arch_no_register_req);
 174         sched_add_after(block, spill_info->spill);
 175
 176         if (spill_to_kill != NULL) {
 177                 exchange(spill_to_kill, spill_info->spill);
 178                 sched_remove(spill_to_kill);
 179         }
 180
 181         /* create spills for the phi values */
 182         for (i = 0; i < arity; ++i) {
 183                 ir_node *in = get_irn_n(phi, i);
 184                 spill_info_t *pred_spill = create_spill(env, in, 1);
 185                 set_irn_n(spill_info->spill, i, pred_spill->spill);
 186         }
 187 }
 188
 189 static void belady(minibelady_env_t *env, ir_node *block);
 190
 191 /**
 192  * Collects all values live-in at block @p block and all phi results in this
 193  * block.
 194  * Then it adds the best values (at most n_regs) to the blocks start_workset.
 195  * The phis among the remaining values get spilled: Introduce pseudo-copies of
 196  * their args to break interference and make it possible to spill them to the
 197  * same spill slot.
 198  */
 199 static block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
 200 {
 201         block_info_t  *block_info;
 202         be_next_use_t  next_use;
 203         ir_loop       *loop;
 204         ir_node       *best_starter, *first;
 205         int            n_cfgpreds;
 206         unsigned       best_time;
 207         int            outer_loop_allowed;
 208
 209         /* Create the block info for this block. */
 210         block_info = new_block_info(&env->obst, block);
 211         n_cfgpreds = get_Block_n_cfgpreds(block);
 212
 213         /* no cfgpred -> no value active */
 214         if (n_cfgpreds == 0) {
 215                 block_info->start_state = NULL;
 216                 return block_info;
 217         }
 218
 219         /* for 1 pred only: simply take the the end-state of the pred */
 220         if (n_cfgpreds == 1) {
 221                 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
 222                 block_info_t *pred_info;
 223
 224                 /* process pred block */
 225                 belady(env, pred_block);
 226
 227                 pred_info = get_block_info(pred_block);
 228
 229                 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
 230                 block_info->start_state = pred_info->end_state;
 231                 return block_info;
 232         }
 233
 234         /* Collect all values living at start of block */
 235         DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
 236         first = sched_first(block);
 237         loop = get_irn_loop(block);
 238         best_starter = NULL;
 239         best_time = USES_INFINITY;
 240         outer_loop_allowed = 1;
 241
 242         /* check all Phis first */
 243         sched_foreach(block, node) {
 244                 if (!is_Phi(node))
 245                         break;
 246                 if (arch_get_irn_register(node) != env->reg)
 247                         continue;
 248
 249                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 250                 next_use = be_get_next_use(env->uses, first, node, 0);
 251
 252                 if (USES_IS_INFINITE(next_use.time)) {
 253                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 254                         continue;
 255                 }
 256
 257                 if (next_use.outermost_loop >= get_loop_depth(loop)) {
 258                         if (outer_loop_allowed || next_use.time < best_time) {
 259                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 260                                      next_use.outermost_loop));
 261
 262                                 if (best_starter != NULL) {
 263                                         /* spill the phi as it is not used */
 264                                         spill_phi(env, best_starter);
 265                                 }
 266                                 best_starter = node;
 267                                 best_time = next_use.time;
 268                                 outer_loop_allowed = 0;
 269                         }
 270                 } else {
 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));
 274                                 if (best_starter != NULL) {
 275                                         /* spill the phi as it is not used */
 276                                         spill_phi(env, best_starter);
 277                                 }
 278                                 best_starter = node;
 279                                 best_time = next_use.time;
 280                         }
 281                 }
 282
 283                 if (best_starter != node) {
 284                         /* spill the phi as it is not used */
 285                         spill_phi(env, best_starter);
 286                 }
 287         }
 288
 289         /* check all Live-Ins */
 290         be_lv_foreach_cls(env->lv, block, be_lv_state_in, env->reg->reg_class, node) {
 291                 if (arch_get_irn_register(node) != env->reg)
 292                         continue;
 293
 294                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 295                 next_use = be_get_next_use(env->uses, first, node, 0);
 296
 297                 if (USES_IS_INFINITE(next_use.time)) {
 298                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 299                         continue;
 300                 }
 301
 302                 if (next_use.outermost_loop >= get_loop_depth(loop)) {
 303                         if (outer_loop_allowed || next_use.time < best_time) {
 304                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 305                                      next_use.outermost_loop));
 306
 307                                 if (best_starter != NULL && is_Phi(best_starter)) {
 308                                         /* spill the phi as it is not used */
 309                                         spill_phi(env, best_starter);
 310                                 }
 311                                 best_starter = node;
 312                                 best_time = next_use.time;
 313                                 outer_loop_allowed = 0;
 314                         }
 315                 } else {
 316                         if (outer_loop_allowed && next_use.time < best_time) {
 317                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 318                                      next_use.outermost_loop));
 319                                 if (best_starter != NULL && is_Phi(best_starter)) {
 320                                         /* spill the phi as it is not used */
 321                                         spill_phi(env, best_starter);
 322                                 }
 323                                 best_starter = node;
 324                                 best_time = next_use.time;
 325                         }
 326                 }
 327         }
 328
 329         block_info->start_state = best_starter;
 330
 331         return block_info;
 332 }
 333
 334 /**
 335  * For the given block @p block, decide for each values
 336  * whether it is used from a register or is reloaded
 337  * before the use.
 338  */
 339 static void belady(minibelady_env_t *env, ir_node *block)
 340 {
 341         ir_node *current_state;
 342         block_info_t *block_info;
 343
 344         /* Don't do a block twice */
 345         if (irn_visited(block))
 346                 return;
 347
 348         /* compute value to start with */
 349         block_info = compute_block_start_state(env, block);
 350
 351         /* get the starting workset for this block */
 352         DBG((dbg, LEVEL_3, "\n"));
 353         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 354
 355         current_state = block_info->start_state;
 356         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 357
 358         /* process the block from start to end */
 359         DBG((dbg, LEVEL_3, "Processing...\n"));
 360
 361         sched_foreach(block, node) {
 362                 int i, arity;
 363                 ir_node *need_val = NULL;
 364
 365                 /* Phis are no real instr (see insert_starters()) */
 366                 if (is_Phi(node))
 367                         continue;
 368
 369                 /* check which state is desired for the node */
 370                 arity = get_irn_arity(node);
 371                 for (i = 0; i < arity; ++i) {
 372                         const arch_register_t *reg;
 373                         ir_node *in = get_irn_n(node, i);
 374
 375                         if (!mode_is_data(get_irn_mode(in)))
 376                                 continue;
 377
 378                         reg = arch_get_irn_register(in);
 379                         if (reg == env->reg) {
 380                                 assert(need_val == NULL);
 381                                 need_val = in;
 382                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 383                         }
 384                 }
 385                 /* create a reload to match state if necessary */
 386                 if (need_val != NULL && need_val != current_state) {
 387                         ir_node *before = node;
 388                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 389                         create_reload(env, need_val, before, current_state);
 390                         current_state = need_val;
 391                 }
 392
 393                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 394
 395                 /* record state changes by the node */
 396                 be_foreach_value(node, value,
 397                         if (!mode_is_data(get_irn_mode(value)))
 398                                 continue;
 399                         arch_register_t const *const reg = arch_get_irn_register(value);
 400                         if (reg != env->reg)
 401                                 continue;
 402                         current_state = value;
 403                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 404                 );
 405         }
 406
 407         /* Remember end-workset for this block */
 408         block_info->end_state = current_state;
 409         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 410 }
 411
 412 static void belady_walker(ir_node *block, void *data)
 413 {
 414         belady((minibelady_env_t*) data, block);
 415 }
 416
 417 /**
 418  * We must adapt the live-outs to the live-ins at each block-border.
 419  */
 420 static void fix_block_borders(ir_node *block, void *data)
 421 {
 422         minibelady_env_t *env = (minibelady_env_t*)data;
 423         int i;
 424         int arity;
 425         block_info_t *block_info;
 426
 427         DBG((dbg, LEVEL_3, "\n"));
 428
 429         block_info = get_block_info(block);
 430
 431         DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
 432              block_info->start_state));
 433
 434         /* process all pred blocks */
 435         arity = get_irn_arity(block);
 436         for (i = 0; i < arity; ++i) {
 437                 ir_node      *pred       = get_Block_cfgpred_block(block, i);
 438                 block_info_t *pred_info  = get_block_info(pred);
 439                 ir_node      *need_state = block_info->start_state;
 440
 441                 if (need_state == NULL)
 442                         continue;
 443
 444                 if (is_Phi(need_state) && get_nodes_block(need_state) == block) {
 445                         need_state = get_irn_n(need_state, i);
 446                 }
 447
 448                 DBG((dbg, LEVEL_3, "  Pred %+F (ends in %+F, we need %+F)\n", pred,
 449                      pred_info->end_state, need_state));
 450
 451                 if (pred_info->end_state != need_state) {
 452                         DBG((dbg, LEVEL_3, "  Creating reload for %+F\n", need_state));
 453                         ir_node *const insert_point = be_get_end_of_block_insertion_point(pred);
 454                         create_reload(env, need_state, insert_point, pred_info->end_state);
 455                 }
 456         }
 457 }
 458
 459 void be_assure_state(ir_graph *irg, const arch_register_t *reg, void *func_env,
 460                      create_spill_func create_spill,
 461                      create_reload_func create_reload)
 462 {
 463         minibelady_env_t env;
 464         spill_info_t *info;
 465         be_lv_t *lv = be_get_irg_liveness(irg);
 466
 467         be_assure_live_sets(irg);
 468         assure_loopinfo(irg);
 469
 470         obstack_init(&env.obst);
 471         env.reg           = reg;
 472         env.func_env      = func_env;
 473         env.create_spill  = create_spill;
 474         env.create_reload = create_reload;
 475         env.lv            = be_get_irg_liveness(irg);
 476         env.uses          = be_begin_uses(irg, env.lv);
 477         env.spills        = NULL;
 478         ir_nodehashmap_init(&env.spill_infos);
 479
 480         assure_doms(irg);
 481         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 482         inc_irg_visited(irg);
 483
 484         /* process blocks */
 485         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 486
 487         /* fix block end_states that don't match the next blocks start_state */
 488         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 489
 490         ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 491
 492         /* reconstruct ssa-form */
 493         info = env.spills;
 494         while (info != NULL) {
 495                 be_ssa_construction_env_t senv;
 496                 size_t i, len;
 497                 ir_node **phis;
 498
 499                 be_ssa_construction_init(&senv, irg);
 500                 if (sched_is_scheduled(info->value))
 501                         be_ssa_construction_add_copy(&senv, info->value);
 502                 be_ssa_construction_add_copies(&senv,
 503                                                info->reloads, ARR_LEN(info->reloads));
 504                 be_ssa_construction_fix_users(&senv, info->value);
 505
 506                 if (lv != NULL) {
 507                         be_ssa_construction_update_liveness_phis(&senv, lv);
 508
 509                         be_liveness_update(lv, info->value);
 510                         len = ARR_LEN(info->reloads);
 511                         for (i = 0; i < len; ++i) {
 512                                 ir_node *reload = info->reloads[i];
 513                                 be_liveness_update(lv, reload);
 514                         }
 515                 }
 516
 517                 phis = be_ssa_construction_get_new_phis(&senv);
 518
 519                 /* set register requirements for phis */
 520                 len = ARR_LEN(phis);
 521                 for (i = 0; i < len; ++i) {
 522                         ir_node *phi = phis[i];
 523                         arch_set_irn_register(phi, env.reg);
 524                 }
 525                 be_ssa_construction_destroy(&senv);
 526
 527                 info = info->next;
 528         }
 529
 530         /* some nodes might be dead now. */
 531         be_remove_dead_nodes_from_schedule(irg);
 532
 533         ir_nodehashmap_destroy(&env.spill_infos);
 534         be_end_uses(env.uses);
 535         obstack_free(&env.obst, NULL);
 536 }
 537
 538 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state)
 539 void be_init_state(void)
 540 {
 541         FIRM_DBG_REGISTER(dbg, "firm.be.state");
 542 }