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  * @version     $Id$
  27  */
  28 #include "config.h"
  29
  30 #include "bestate.h"
  31
  32 #include "obst.h"
  33 #include "irgraph_t.h"
  34 #include "irnode_t.h"
  35 #include "irgwalk.h"
  36 #include "irloop.h"
  37 #include "iredges_t.h"
  38 #include "ircons_t.h"
  39 #include "irgmod.h"
  40 #include "irnodeset.h"
  41 #include "irnodemap.h"
  42 #include "adt/cpset.h"
  43
  44 #include "bearch.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 "bessaconstr.h"
  52
  53 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  54
  55 typedef struct spill_info_t {
  56         struct spill_info_t *next;
  57         ir_node *value;
  58         ir_node *spill;
  59         ir_node **reloads;
  60 } spill_info_t;
  61
  62 typedef struct minibelady_env_t {
  63         struct obstack         obst;
  64         const arch_register_t *reg;
  65         const be_lv_t         *lv;
  66         void                  *func_env;
  67         create_reload_func     create_reload;
  68         create_spill_func      create_spill;
  69         spill_info_t          *spills;
  70         ir_nodemap_t           spill_infos;
  71
  72         be_uses_t             *uses;           /**< env for the next-use magic */
  73 } minibelady_env_t;
  74
  75 typedef struct block_info_t {
  76         ir_node *start_state;
  77         ir_node *end_state;
  78 } block_info_t;
  79
  80 static inline block_info_t *new_block_info(struct obstack *obst, ir_node *block)
  81 {
  82         block_info_t *res = OALLOCZ(obst, block_info_t);
  83
  84         assert(is_Block(block));
  85         set_irn_link(block, res);
  86         mark_irn_visited(block);
  87
  88         return res;
  89 }
  90
  91 static inline block_info_t *get_block_info(ir_node *block)
  92 {
  93         assert(irn_visited(block));
  94         return (block_info_t*) get_irn_link(block);
  95 }
  96
  97 static inline spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
  98 {
  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);
 102
 103         ir_nodemap_insert(&env->spill_infos, state, spill_info);
 104         //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
 105
 106         spill_info->next = env->spills;
 107         env->spills = spill_info;
 108
 109         return spill_info;
 110 }
 111
 112 static inline spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
 113 {
 114         spill_info_t *spill_info
 115                 = (spill_info_t*) ir_nodemap_get(&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_Proj(next) || is_Phi(next) || be_is_Keep(next)
 139                         || (arch_irn_get_flags(next) & arch_irn_flags_prolog));
 140         } else {
 141                 after = state;
 142         }
 143         spill_info->spill = env->create_spill(env->func_env, state, force, after);
 144
 145         return spill_info;
 146 }
 147
 148 static void create_reload(minibelady_env_t *env, ir_node *state,
 149                           ir_node *before, ir_node *last_state)
 150 {
 151         spill_info_t *spill_info = create_spill(env, state, 0);
 152         ir_node *spill = spill_info->spill;
 153         ir_node *reload;
 154
 155         reload = env->create_reload(env->func_env, state, spill, before,
 156                                     last_state);
 157         ARR_APP1(ir_node*, spill_info->reloads, reload);
 158 }
 159
 160 static void spill_phi(minibelady_env_t *env, ir_node *phi)
 161 {
 162         ir_graph     *irg           = get_irn_irg(phi);
 163         ir_node      *block         = get_nodes_block(phi);
 164         int           arity         = get_irn_arity(phi);
 165         ir_node     **in            = ALLOCAN(ir_node*, arity);
 166         ir_node      *dummy         = new_r_Dummy(irg, mode_M);
 167         ir_node      *spill_to_kill = NULL;
 168         spill_info_t *spill_info;
 169         int           i;
 170
 171         /* does a spill exist for the phis value? */
 172         spill_info = get_spill_info(env, phi);
 173         if (spill_info != NULL) {
 174                 spill_to_kill = spill_info->spill;
 175         } else {
 176                 spill_info = create_spill_info(env, phi);
 177         }
 178
 179         /* create a new phi-M with bad preds */
 180         for (i = 0; i < arity; ++i) {
 181                 in[i] = dummy;
 182         }
 183
 184         DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
 185
 186         /* create a Phi-M */
 187         spill_info->spill = be_new_Phi(block, arity, in, mode_M, NULL);
 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         ir_node       *node;
 220         int            n_cfgpreds;
 221         unsigned       best_time;
 222         int            outer_loop_allowed;
 223         int            i;
 224
 225         /* Create the block info for this block. */
 226         block_info = new_block_info(&env->obst, block);
 227         n_cfgpreds = get_Block_n_cfgpreds(block);
 228
 229         /* no cfgpred -> no value active */
 230         if (n_cfgpreds == 0) {
 231                 block_info->start_state = NULL;
 232                 return block_info;
 233         }
 234
 235         /* for 1 pred only: simply take the the end-state of the pred */
 236         if (n_cfgpreds == 1) {
 237                 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
 238                 block_info_t *pred_info;
 239
 240                 /* process pred block */
 241                 belady(env, pred_block);
 242
 243                 pred_info = get_block_info(pred_block);
 244
 245                 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
 246                 block_info->start_state = pred_info->end_state;
 247                 return block_info;
 248         }
 249
 250         /* Collect all values living at start of block */
 251         DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
 252         first = sched_first(block);
 253         loop = get_irn_loop(block);
 254         best_starter = NULL;
 255         best_time = USES_INFINITY;
 256         outer_loop_allowed = 1;
 257
 258         /* check all Phis first */
 259         sched_foreach(block, node) {
 260                 if (!is_Phi(node))
 261                         break;
 262                 if (arch_get_irn_register(node) != env->reg)
 263                         continue;
 264
 265                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 266                 next_use = be_get_next_use(env->uses, first, node, 0);
 267
 268                 if (USES_IS_INFINITE(next_use.time)) {
 269                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 270                         continue;
 271                 }
 272
 273                 if (next_use.outermost_loop >= get_loop_depth(loop)) {
 274                         if (outer_loop_allowed || next_use.time < best_time) {
 275                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 276                                      next_use.outermost_loop));
 277
 278                                 if (best_starter != NULL) {
 279                                         /* spill the phi as it is not used */
 280                                         spill_phi(env, best_starter);
 281                                 }
 282                                 best_starter = node;
 283                                 best_time = next_use.time;
 284                                 outer_loop_allowed = 0;
 285                         }
 286                 } else {
 287                         if (outer_loop_allowed && next_use.time < best_time) {
 288                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 289                                      next_use.outermost_loop));
 290                                 if (best_starter != NULL) {
 291                                         /* spill the phi as it is not used */
 292                                         spill_phi(env, best_starter);
 293                                 }
 294                                 best_starter = node;
 295                                 best_time = next_use.time;
 296                         }
 297                 }
 298
 299                 if (best_starter != node) {
 300                         /* spill the phi as it is not used */
 301                         spill_phi(env, best_starter);
 302                 }
 303         }
 304
 305         /* check all Live-Ins */
 306         be_lv_foreach(env->lv, block, be_lv_state_in, i) {
 307                 node = be_lv_get_irn(env->lv, block, i);
 308
 309                 if (!mode_is_data(get_irn_mode(node)))
 310                         continue;
 311
 312                 if (arch_get_irn_register(node) != env->reg)
 313                         continue;
 314
 315                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 316                 next_use = be_get_next_use(env->uses, first, node, 0);
 317
 318                 if (USES_IS_INFINITE(next_use.time)) {
 319                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 320                         continue;
 321                 }
 322
 323                 if (next_use.outermost_loop >= get_loop_depth(loop)) {
 324                         if (outer_loop_allowed || next_use.time < best_time) {
 325                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 326                                      next_use.outermost_loop));
 327
 328                                 if (best_starter != NULL && is_Phi(best_starter)) {
 329                                         /* spill the phi as it is not used */
 330                                         spill_phi(env, best_starter);
 331                                 }
 332                                 best_starter = node;
 333                                 best_time = next_use.time;
 334                                 outer_loop_allowed = 0;
 335                         }
 336                 } else {
 337                         if (outer_loop_allowed && next_use.time < best_time) {
 338                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 339                                      next_use.outermost_loop));
 340                                 if (best_starter != NULL && is_Phi(best_starter)) {
 341                                         /* spill the phi as it is not used */
 342                                         spill_phi(env, best_starter);
 343                                 }
 344                                 best_starter = node;
 345                                 best_time = next_use.time;
 346                         }
 347                 }
 348         }
 349
 350         block_info->start_state = best_starter;
 351
 352         return block_info;
 353 }
 354
 355 static ir_node *get_reload_point(ir_node *before)
 356 {
 357         while (true) {
 358                 ir_node *prev = sched_prev(before);
 359                 if (! (arch_irn_get_flags(prev) & arch_irn_flags_epilog))
 360                         break;
 361                 before = prev;
 362         }
 363         return before;
 364 }
 365
 366 /**
 367  * For the given block @p block, decide for each values
 368  * whether it is used from a register or is reloaded
 369  * before the use.
 370  */
 371 static void belady(minibelady_env_t *env, ir_node *block)
 372 {
 373         ir_node *current_state;
 374         ir_node *node;
 375         block_info_t *block_info;
 376
 377         /* Don't do a block twice */
 378         if (irn_visited(block))
 379                 return;
 380
 381         /* compute value to start with */
 382         block_info = compute_block_start_state(env, block);
 383
 384         /* get the starting workset for this block */
 385         DBG((dbg, LEVEL_3, "\n"));
 386         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 387
 388         current_state = block_info->start_state;
 389         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 390
 391         /* process the block from start to end */
 392         DBG((dbg, LEVEL_3, "Processing...\n"));
 393
 394         sched_foreach(block, node) {
 395                 int i, arity;
 396                 ir_node *need_val = NULL;
 397
 398                 /* projs are handled with the tuple value.
 399                  * Phis are no real instr (see insert_starters()) */
 400                 if (is_Proj(node) || is_Phi(node)) {
 401                         continue;
 402                 }
 403
 404                 /* check which state is desired for the node */
 405                 arity = get_irn_arity(node);
 406                 for (i = 0; i < arity; ++i) {
 407                         const arch_register_t *reg;
 408                         ir_node *in = get_irn_n(node, i);
 409
 410                         if (!mode_is_data(get_irn_mode(in)))
 411                                 continue;
 412
 413                         reg = arch_get_irn_register(in);
 414                         if (reg == env->reg) {
 415                                 assert(need_val == NULL);
 416                                 need_val = in;
 417                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 418                         }
 419                 }
 420                 /* create a reload to match state if necessary */
 421                 if (need_val != NULL && need_val != current_state) {
 422                         ir_node *before = get_reload_point(node);
 423                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 424                         create_reload(env, need_val, before, current_state);
 425                         current_state = need_val;
 426                 }
 427
 428                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 429
 430                 /* record state changes by the node */
 431                 if (get_irn_mode(node) == mode_T) {
 432                         const ir_edge_t *edge;
 433
 434                         foreach_out_edge(node, edge) {
 435                                 const arch_register_t *reg;
 436                                 ir_node *proj = get_edge_src_irn(edge);
 437
 438                                 if (!mode_is_data(get_irn_mode(proj)))
 439                                         continue;
 440
 441                                 reg = arch_get_irn_register(proj);
 442                                 if (reg == env->reg) {
 443                                         current_state = proj;
 444                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 445                                 }
 446                         }
 447                 } else {
 448                         if (mode_is_data(get_irn_mode(node))) {
 449                                 const arch_register_t *reg = arch_get_irn_register(node);
 450                                 if (reg == env->reg) {
 451                                         current_state = node;
 452                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 453                                 }
 454                         }
 455                 }
 456         }
 457
 458         /* Remember end-workset for this block */
 459         block_info->end_state = current_state;
 460         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 461 }
 462
 463 static void belady_walker(ir_node *block, void *data)
 464 {
 465         belady((minibelady_env_t*) data, block);
 466 }
 467
 468 static ir_node *get_end_of_block_insertion_point(ir_node *block)
 469 {
 470         ir_node *last = sched_last(block);
 471
 472         /* skip Projs and Keep-alikes behind the jump... */
 473         while (is_Proj(last) || be_is_Keep(last)) {
 474                 last = sched_prev(last);
 475         }
 476
 477         if (!is_cfop(last)) {
 478                 last = sched_next(last);
 479                 /* last node must be a cfop, only exception is the start block */
 480                 assert(last == get_irg_start_block(get_irn_irg(block)));
 481         }
 482
 483         return last;
 484 }
 485
 486 /**
 487  * We must adapt the live-outs to the live-ins at each block-border.
 488  */
 489 static void fix_block_borders(ir_node *block, void *data)
 490 {
 491         minibelady_env_t *env = (minibelady_env_t*)data;
 492         ir_graph *irg = get_irn_irg(block);
 493         ir_node *startblock = get_irg_start_block(irg);
 494         int i;
 495         int arity;
 496         block_info_t *block_info;
 497
 498         if (block == startblock)
 499                 return;
 500
 501         DBG((dbg, LEVEL_3, "\n"));
 502
 503         block_info = get_block_info(block);
 504
 505         DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
 506              block_info->start_state));
 507
 508         /* process all pred blocks */
 509         arity = get_irn_arity(block);
 510         for (i = 0; i < arity; ++i) {
 511                 ir_node      *pred       = get_Block_cfgpred_block(block, i);
 512                 block_info_t *pred_info  = get_block_info(pred);
 513                 ir_node      *need_state = block_info->start_state;
 514
 515                 if (need_state == NULL)
 516                         continue;
 517
 518                 if (is_Phi(need_state) && get_nodes_block(need_state) == block) {
 519                         need_state = get_irn_n(need_state, i);
 520                 }
 521
 522                 DBG((dbg, LEVEL_3, "  Pred %+F (ends in %+F, we need %+F)\n", pred,
 523                      pred_info->end_state, need_state));
 524
 525                 if (pred_info->end_state != need_state) {
 526                         ir_node *insert_point = get_end_of_block_insertion_point(pred);
 527
 528
 529                         DBG((dbg, LEVEL_3, "  Creating reload for %+F\n", need_state));
 530                         create_reload(env, need_state, insert_point, pred_info->end_state);
 531                 }
 532         }
 533 }
 534
 535 void be_assure_state(ir_graph *irg, const arch_register_t *reg, void *func_env,
 536                      create_spill_func create_spill,
 537                      create_reload_func create_reload)
 538 {
 539         minibelady_env_t env;
 540         spill_info_t *info;
 541         be_lv_t *lv = be_assure_liveness(irg);
 542
 543         be_liveness_assure_sets(lv);
 544         /* construct control flow loop tree */
 545         if (! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
 546                 construct_cf_backedges(irg);
 547         }
 548
 549         obstack_init(&env.obst);
 550         env.reg           = reg;
 551         env.func_env      = func_env;
 552         env.create_spill  = create_spill;
 553         env.create_reload = create_reload;
 554         env.lv            = be_get_irg_liveness(irg);
 555         env.uses          = be_begin_uses(irg, env.lv);
 556         env.spills        = NULL;
 557         ir_nodemap_init(&env.spill_infos);
 558
 559         assure_doms(irg);
 560         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 561         inc_irg_visited(irg);
 562
 563         /* process blocks */
 564         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 565
 566         /* fix block end_states that don't match the next blocks start_state */
 567         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 568
 569         ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 570
 571         /* reconstruct ssa-form */
 572         info = env.spills;
 573         while (info != NULL) {
 574                 be_ssa_construction_env_t senv;
 575                 size_t i, len;
 576                 ir_node **phis;
 577
 578                 be_ssa_construction_init(&senv, irg);
 579                 if (sched_is_scheduled(info->value))
 580                         be_ssa_construction_add_copy(&senv, info->value);
 581                 be_ssa_construction_add_copies(&senv,
 582                                                info->reloads, ARR_LEN(info->reloads));
 583                 be_ssa_construction_fix_users(&senv, info->value);
 584
 585                 if (lv != NULL) {
 586                         be_ssa_construction_update_liveness_phis(&senv, lv);
 587
 588                         be_liveness_update(lv, info->value);
 589                         len = ARR_LEN(info->reloads);
 590                         for (i = 0; i < len; ++i) {
 591                                 ir_node *reload = info->reloads[i];
 592                                 be_liveness_update(lv, reload);
 593                         }
 594                 }
 595
 596                 phis = be_ssa_construction_get_new_phis(&senv);
 597
 598                 /* set register requirements for phis */
 599                 len = ARR_LEN(phis);
 600                 for (i = 0; i < len; ++i) {
 601                         ir_node *phi = phis[i];
 602                         arch_set_irn_register(phi, env.reg);
 603                 }
 604                 be_ssa_construction_destroy(&senv);
 605
 606                 info = info->next;
 607         }
 608
 609         /* some nodes might be dead now. */
 610         be_remove_dead_nodes_from_schedule(irg);
 611
 612         ir_nodemap_destroy(&env.spill_infos);
 613         be_end_uses(env.uses);
 614         obstack_free(&env.obst, NULL);
 615 }
 616
 617 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);
 618 void be_init_state(void)
 619 {
 620         FIRM_DBG_REGISTER(dbg, "firm.be.state");
 621 }