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

   1 /*
   2  * Copyright (C) 1995-2008 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 "bessaconstr.h"
  51
  52 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  53
  54 typedef struct spill_info_t {
  55         struct spill_info_t *next;
  56         ir_node *value;
  57         ir_node *spill;
  58         ir_node **reloads;
  59 } spill_info_t;
  60
  61 typedef struct minibelady_env_t {
  62         struct obstack         obst;
  63         const arch_register_t *reg;
  64         const be_lv_t         *lv;
  65         void                  *func_env;
  66         create_reload_func     create_reload;
  67         create_spill_func      create_spill;
  68         spill_info_t          *spills;
  69         ir_nodemap_t           spill_infos;
  70
  71         be_uses_t             *uses;           /**< env for the next-use magic */
  72 } minibelady_env_t;
  73
  74 typedef struct block_info_t {
  75         ir_node *start_state;
  76         ir_node *end_state;
  77 } block_info_t;
  78
  79 static inline
  80 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
  92 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
  99 spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
 100 {
 101         spill_info_t *spill_info = OALLOCZ(&env->obst, spill_info_t);
 102         spill_info->value = state;
 103         spill_info->reloads = NEW_ARR_F(ir_node*, 0);
 104
 105         ir_nodemap_insert(&env->spill_infos, state, spill_info);
 106         //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
 107
 108         spill_info->next = env->spills;
 109         env->spills = spill_info;
 110
 111         return spill_info;
 112 }
 113
 114 static inline
 115 spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
 116 {
 117         spill_info_t *spill_info
 118                 = (spill_info_t*) ir_nodemap_get(&env->spill_infos, node);
 119         //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
 120         return spill_info;
 121 }
 122
 123 static
 124 spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
 125 {
 126         spill_info_t *spill_info;
 127         ir_node *next;
 128         ir_node *after;
 129
 130         spill_info = get_spill_info(env, state);
 131         if(spill_info == NULL) {
 132                 spill_info = create_spill_info(env, state);
 133         } else if(spill_info->spill != NULL) {
 134                 return spill_info;
 135         }
 136
 137         if(sched_is_scheduled(state)) {
 138                 next = state;
 139                 do {
 140                         after = next;
 141                         next = sched_next(after);
 142                 } while(is_Proj(next) || is_Phi(next) || be_is_Keep(next));
 143         } else {
 144                 after = state;
 145         }
 146         spill_info->spill = env->create_spill(env->func_env, state, force, after);
 147
 148         return spill_info;
 149 }
 150
 151 static
 152 void create_reload(minibelady_env_t *env, ir_node *state, ir_node *before,
 153                    ir_node *last_state)
 154 {
 155         spill_info_t *spill_info = create_spill(env, state, 0);
 156         ir_node *spill = spill_info->spill;
 157         ir_node *reload;
 158
 159         reload = env->create_reload(env->func_env, state, spill, before,
 160                                     last_state);
 161         ARR_APP1(ir_node*, spill_info->reloads, reload);
 162 }
 163
 164 static
 165 void spill_phi(minibelady_env_t *env, ir_node *phi)
 166 {
 167         ir_graph     *irg           = get_irn_irg(phi);
 168         ir_node      *block         = get_nodes_block(phi);
 169         int           arity         = get_irn_arity(phi);
 170         ir_node     **in            = ALLOCAN(ir_node*, arity);
 171         ir_node      *spill_to_kill = NULL;
 172         spill_info_t *spill_info;
 173         int           i;
 174
 175         /* does a spill exist for the phis value? */
 176         spill_info = get_spill_info(env, phi);
 177         if(spill_info != NULL) {
 178                 spill_to_kill = spill_info->spill;
 179         } else {
 180                 spill_info = create_spill_info(env, phi);
 181         }
 182
 183         /* create a new phi-M with bad preds */
 184         for(i = 0; i < arity; ++i) {
 185                 in[i] = new_r_Unknown(irg, mode_M);
 186         }
 187
 188         DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
 189
 190         /* create a Phi-M */
 191         spill_info->spill = new_r_Phi(block, arity, in, mode_M);
 192
 193         if(spill_to_kill != NULL) {
 194                 exchange(spill_to_kill, spill_info->spill);
 195                 sched_remove(spill_to_kill);
 196         }
 197
 198         /* create spills for the phi values */
 199         for(i = 0; i < arity; ++i) {
 200                 ir_node *in = get_irn_n(phi, i);
 201                 spill_info_t *pred_spill = create_spill(env, in, 1);
 202                 set_irn_n(spill_info->spill, i, pred_spill->spill);
 203         }
 204 }
 205
 206 static
 207 void belady(minibelady_env_t *env, ir_node *block);
 208
 209 /**
 210  * Collects all values live-in at block @p block and all phi results in this
 211  * block.
 212  * Then it adds the best values (at most n_regs) to the blocks start_workset.
 213  * The phis among the remaining values get spilled: Introduce psudo-copies of
 214  * their args to break interference and make it possible to spill them to the
 215  * same spill slot.
 216  */
 217 static
 218 block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
 219 {
 220         block_info_t  *block_info;
 221         be_next_use_t  next_use;
 222         ir_loop       *loop;
 223         ir_node       *best_starter, *first;
 224         ir_node       *node;
 225         int            n_cfgpreds;
 226         unsigned       best_time;
 227         int            outer_loop_allowed;
 228         int            i;
 229
 230         /* Create the block info for this block. */
 231         block_info = new_block_info(&env->obst, block);
 232         n_cfgpreds = get_Block_n_cfgpreds(block);
 233
 234         /* no cfgpred -> no value active */
 235         if(n_cfgpreds == 0) {
 236                 block_info->start_state = NULL;
 237                 return block_info;
 238         }
 239
 240         /* for 1 pred only: simply take the the end-state of the pred */
 241         if(n_cfgpreds == 1) {
 242                 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
 243                 block_info_t *pred_info;
 244
 245                 /* process pred block */
 246                 belady(env, pred_block);
 247
 248                 pred_info = get_block_info(pred_block);
 249
 250                 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
 251                 block_info->start_state = pred_info->end_state;
 252                 return block_info;
 253         }
 254
 255         /* Collect all values living at start of block */
 256         DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
 257         first = sched_first(block);
 258         loop = get_irn_loop(block);
 259         best_starter = NULL;
 260         best_time = USES_INFINITY;
 261         outer_loop_allowed = 1;
 262
 263         /* check all Phis first */
 264         sched_foreach(block, node) {
 265                 if (!is_Phi(node))
 266                         break;
 267                 if (arch_get_irn_register(node) != env->reg)
 268                         continue;
 269
 270                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 271                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 272
 273                 if(USES_IS_INFINITE(next_use.time)) {
 274                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 275                         continue;
 276                 }
 277
 278                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 279                         if(outer_loop_allowed || next_use.time < best_time) {
 280                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 281                                      next_use.outermost_loop));
 282
 283                                 if(best_starter != NULL) {
 284                                         /* spill the phi as it is not used */
 285                                         spill_phi(env, best_starter);
 286                                 }
 287                                 best_starter = node;
 288                                 best_time = next_use.time;
 289                                 outer_loop_allowed = 0;
 290                         }
 291                 } else {
 292                         if(outer_loop_allowed && next_use.time < best_time) {
 293                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 294                                      next_use.outermost_loop));
 295                                 if(best_starter != NULL) {
 296                                         /* spill the phi as it is not used */
 297                                         spill_phi(env, best_starter);
 298                                 }
 299                                 best_starter = node;
 300                                 best_time = next_use.time;
 301                         }
 302                 }
 303
 304                 if(best_starter != node) {
 305                         /* spill the phi as it is not used */
 306                         spill_phi(env, best_starter);
 307                 }
 308         }
 309
 310         /* check all Live-Ins */
 311         be_lv_foreach(env->lv, block, be_lv_state_in, i) {
 312                 node = be_lv_get_irn(env->lv, block, i);
 313
 314                 if(!mode_is_data(get_irn_mode(node)))
 315                         continue;
 316
 317                 if (arch_get_irn_register(node) != env->reg)
 318                         continue;
 319
 320                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 321                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 322
 323                 if(USES_IS_INFINITE(next_use.time)) {
 324                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 325                         continue;
 326                 }
 327
 328                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 329                         if(outer_loop_allowed || next_use.time < best_time) {
 330                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 331                                      next_use.outermost_loop));
 332
 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                                 outer_loop_allowed = 0;
 340                         }
 341                 } else {
 342                         if(outer_loop_allowed && next_use.time < best_time) {
 343                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 344                                      next_use.outermost_loop));
 345                                 if(best_starter != NULL && is_Phi(best_starter)) {
 346                                         /* spill the phi as it is not used */
 347                                         spill_phi(env, best_starter);
 348                                 }
 349                                 best_starter = node;
 350                                 best_time = next_use.time;
 351                         }
 352                 }
 353         }
 354
 355         block_info->start_state = best_starter;
 356
 357         return block_info;
 358 }
 359
 360 /**
 361  * For the given block @p block, decide for each values
 362  * whether it is used from a register or is reloaded
 363  * before the use.
 364  */
 365 static
 366 void belady(minibelady_env_t *env, ir_node *block)
 367 {
 368         ir_node *current_state;
 369         ir_node *node;
 370         block_info_t *block_info;
 371
 372         /* Don't do a block twice */
 373         if(irn_visited(block))
 374                 return;
 375
 376         /* compute value to start with */
 377         block_info = compute_block_start_state(env, block);
 378
 379         /* get the starting workset for this block */
 380         DBG((dbg, LEVEL_3, "\n"));
 381         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 382
 383         current_state = block_info->start_state;
 384         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 385
 386         /* process the block from start to end */
 387         DBG((dbg, LEVEL_3, "Processing...\n"));
 388
 389         sched_foreach(block, node) {
 390                 int i, arity;
 391                 ir_node *need_val = NULL;
 392
 393                 /* projs are handled with the tuple value.
 394                  * Phis are no real instr (see insert_starters()) */
 395                 if (is_Proj(node) || is_Phi(node)) {
 396                         continue;
 397                 }
 398
 399                 /* check which state is desired for the node */
 400                 arity = get_irn_arity(node);
 401                 for(i = 0; i < arity; ++i) {
 402                         const arch_register_t *reg;
 403                         ir_node *in = get_irn_n(node, i);
 404
 405                         if(!mode_is_data(get_irn_mode(in)))
 406                                 continue;
 407
 408                         reg = arch_get_irn_register(in);
 409                         if(reg == env->reg) {
 410                                 assert(need_val == NULL);
 411                                 need_val = in;
 412                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 413                         }
 414                 }
 415                 /* create a reload to match state if necessary */
 416                 if(need_val != NULL && need_val != current_state) {
 417                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 418                         create_reload(env, need_val, node, current_state);
 419                         current_state = need_val;
 420                 }
 421
 422                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 423
 424                 /* record state changes by the node */
 425                 if (get_irn_mode(node) == mode_T) {
 426                         const ir_edge_t *edge;
 427
 428                         foreach_out_edge(node, edge) {
 429                                 const arch_register_t *reg;
 430                                 ir_node *proj = get_edge_src_irn(edge);
 431
 432                                 if(!mode_is_data(get_irn_mode(proj)))
 433                                         continue;
 434
 435                                 reg = arch_get_irn_register(proj);
 436                                 if(reg == env->reg) {
 437                                         current_state = proj;
 438                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 439                                 }
 440                         }
 441                 } else {
 442                         if(mode_is_data(get_irn_mode(node))) {
 443                                 const arch_register_t *reg = arch_get_irn_register(node);
 444                                 if(reg == env->reg) {
 445                                         current_state = node;
 446                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 447                                 }
 448                         }
 449                 }
 450         }
 451
 452         /* Remember end-workset for this block */
 453         block_info->end_state = current_state;
 454         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 455 }
 456
 457 static
 458 void belady_walker(ir_node *block, void *data)
 459 {
 460         belady((minibelady_env_t*) data, block);
 461 }
 462
 463 static
 464 ir_node *get_end_of_block_insertion_point(ir_node *block)
 465 {
 466         ir_node *last = sched_last(block);
 467
 468         /* skip Projs and Keep-alikes behind the jump... */
 469         while(is_Proj(last) || be_is_Keep(last)) {
 470                 last = sched_prev(last);
 471         }
 472
 473         if(!is_cfop(last)) {
 474                 last = sched_next(last);
 475                 /* last node must be a cfop, only exception is the start block */
 476                 assert(last     == get_irg_start_block(get_irn_irg(block)));
 477         }
 478
 479         return last;
 480 }
 481
 482 /**
 483  * We must adapt the live-outs to the live-ins at each block-border.
 484  */
 485 static
 486 void fix_block_borders(ir_node *block, void *data) {
 487         minibelady_env_t *env = data;
 488         ir_graph *irg = get_irn_irg(block);
 489         ir_node *startblock = get_irg_start_block(irg);
 490         int i;
 491         int arity;
 492         block_info_t *block_info;
 493
 494         if(block == startblock)
 495                 return;
 496
 497         DBG((dbg, LEVEL_3, "\n"));
 498
 499         block_info = get_block_info(block);
 500
 501         DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
 502              block_info->start_state));
 503
 504         /* process all pred blocks */
 505         arity = get_irn_arity(block);
 506         for (i = 0; i < arity; ++i) {
 507                 ir_node      *pred       = get_Block_cfgpred_block(block, i);
 508                 block_info_t *pred_info  = get_block_info(pred);
 509                 ir_node      *need_state = block_info->start_state;
 510
 511                 if(need_state == NULL)
 512                         continue;
 513
 514                 if(is_Phi(need_state) && get_nodes_block(need_state) == block) {
 515                         need_state = get_irn_n(need_state, i);
 516                 }
 517
 518                 DBG((dbg, LEVEL_3, "  Pred %+F (ends in %+F, we need %+F)\n", pred,
 519                      pred_info->end_state, need_state));
 520
 521                 if(pred_info->end_state != need_state) {
 522                         ir_node *insert_point = get_end_of_block_insertion_point(pred);
 523
 524
 525                         DBG((dbg, LEVEL_3, "  Creating reload for %+F\n", need_state));
 526                         create_reload(env, need_state, insert_point, pred_info->end_state);
 527                 }
 528         }
 529 }
 530
 531 void be_assure_state(be_irg_t *birg, const arch_register_t *reg, void *func_env,
 532                      create_spill_func create_spill,
 533                      create_reload_func create_reload) {
 534         minibelady_env_t env;
 535         ir_graph *irg = be_get_birg_irg(birg);
 536         spill_info_t *info;
 537         be_lv_t *lv = be_assure_liveness(birg);
 538
 539         be_liveness_assure_sets(lv);
 540         /* construct control flow loop tree */
 541         if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
 542                 construct_cf_backedges(irg);
 543         }
 544
 545         obstack_init(&env.obst);
 546         env.reg           = reg;
 547         env.func_env      = func_env;
 548         env.create_spill  = create_spill;
 549         env.create_reload = create_reload;
 550         env.lv            = be_get_birg_liveness(birg);
 551         env.uses          = be_begin_uses(irg, env.lv);
 552         env.spills        = NULL;
 553         ir_nodemap_init(&env.spill_infos);
 554
 555         assure_doms(irg);
 556         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 557         inc_irg_visited(irg);
 558
 559         /* process blocks */
 560         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 561
 562         /* fix block end_states that don't match the next blocks start_state */
 563         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 564
 565         ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 566
 567         /* reconstruct ssa-form */
 568         info = env.spills;
 569         while(info != NULL) {
 570                 be_ssa_construction_env_t senv;
 571                 int i, len;
 572                 ir_node **phis;
 573
 574                 be_ssa_construction_init(&senv, birg);
 575                 if(sched_is_scheduled(info->value))
 576                         be_ssa_construction_add_copy(&senv, info->value);
 577                 be_ssa_construction_add_copies(&senv,
 578                                                info->reloads, ARR_LEN(info->reloads));
 579                 be_ssa_construction_fix_users(&senv, info->value);
 580
 581                 if(lv != NULL) {
 582                         be_ssa_construction_update_liveness_phis(&senv, lv);
 583
 584                         be_liveness_update(lv, info->value);
 585                         len = ARR_LEN(info->reloads);
 586                         for(i = 0; i < len; ++i) {
 587                                 ir_node *reload = info->reloads[i];
 588                                 be_liveness_update(lv, reload);
 589                         }
 590                 }
 591
 592                 phis = be_ssa_construction_get_new_phis(&senv);
 593
 594                 /* set register requirements for phis */
 595                 len = ARR_LEN(phis);
 596                 for(i = 0; i < len; ++i) {
 597                         ir_node *phi = phis[i];
 598                         arch_set_irn_register(phi, env.reg);
 599                 }
 600                 be_ssa_construction_destroy(&senv);
 601
 602                 info = info->next;
 603         }
 604
 605         /* some nodes might be dead now. */
 606         be_remove_dead_nodes_from_schedule(birg);
 607
 608         ir_nodemap_destroy(&env.spill_infos);
 609         be_end_uses(env.uses);
 610         obstack_free(&env.obst, NULL);
 611 }
 612
 613 void be_init_state(void)
 614 {
 615         FIRM_DBG_REGISTER(dbg, "firm.be.state");
 616 }
 617
 618 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);