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 "beuses.h"
  45 #include "besched.h"
  46 #include "belive_t.h"
  47 #include "bemodule.h"
  48 #include "benode.h"
  49 #include "beirgmod.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_nodehashmap_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 block_info_t *new_block_info(struct obstack *obst, ir_node *block)
  80 {
  81         block_info_t *res = OALLOCZ(obst, block_info_t);
  82
  83         assert(is_Block(block));
  84         set_irn_link(block, res);
  85         mark_irn_visited(block);
  86
  87         return res;
  88 }
  89
  90 static inline block_info_t *get_block_info(ir_node *block)
  91 {
  92         assert(irn_visited(block));
  93         return (block_info_t*) get_irn_link(block);
  94 }
  95
  96 static inline spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
  97 {
  98         spill_info_t *spill_info = OALLOCZ(&env->obst, spill_info_t);
  99         spill_info->value = state;
 100         spill_info->reloads = NEW_ARR_F(ir_node*, 0);
 101
 102         ir_nodehashmap_insert(&env->spill_infos, state, spill_info);
 103         //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
 104
 105         spill_info->next = env->spills;
 106         env->spills = spill_info;
 107
 108         return spill_info;
 109 }
 110
 111 static inline spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
 112 {
 113         spill_info_t *spill_info = ir_nodehashmap_get(spill_info_t, &env->spill_infos, node);
 114         //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
 115         return spill_info;
 116 }
 117
 118 static spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
 119 {
 120         spill_info_t *spill_info;
 121         ir_node *next;
 122         ir_node *after;
 123
 124         spill_info = get_spill_info(env, state);
 125         if (spill_info == NULL) {
 126                 spill_info = create_spill_info(env, state);
 127         } else if (spill_info->spill != NULL) {
 128                 return spill_info;
 129         }
 130
 131         if (sched_is_scheduled(state)) {
 132                 next = state;
 133                 do {
 134                         after = next;
 135                         next = sched_next(after);
 136                 } while (is_Proj(next) || is_Phi(next) || be_is_Keep(next));
 137         } else {
 138                 after = state;
 139         }
 140         spill_info->spill = env->create_spill(env->func_env, state, force, after);
 141
 142         return spill_info;
 143 }
 144
 145 static void create_reload(minibelady_env_t *env, ir_node *state,
 146                           ir_node *before, ir_node *last_state)
 147 {
 148         spill_info_t *spill_info = create_spill(env, state, 0);
 149         ir_node *spill = spill_info->spill;
 150         ir_node *reload;
 151
 152         reload = env->create_reload(env->func_env, state, spill, before,
 153                                     last_state);
 154         ARR_APP1(ir_node*, spill_info->reloads, reload);
 155 }
 156
 157 static void spill_phi(minibelady_env_t *env, ir_node *phi)
 158 {
 159         ir_graph     *irg           = get_irn_irg(phi);
 160         ir_node      *block         = get_nodes_block(phi);
 161         int           arity         = get_irn_arity(phi);
 162         ir_node     **phi_in        = ALLOCAN(ir_node*, arity);
 163         ir_node      *dummy         = new_r_Dummy(irg, mode_M);
 164         ir_node      *spill_to_kill = NULL;
 165         spill_info_t *spill_info;
 166         int           i;
 167
 168         /* does a spill exist for the phis value? */
 169         spill_info = get_spill_info(env, phi);
 170         if (spill_info != NULL) {
 171                 spill_to_kill = spill_info->spill;
 172         } else {
 173                 spill_info = create_spill_info(env, phi);
 174         }
 175
 176         /* create a new phi-M with bad preds */
 177         for (i = 0; i < arity; ++i) {
 178                 phi_in[i] = dummy;
 179         }
 180
 181         DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
 182
 183         /* create a Phi-M */
 184         spill_info->spill = be_new_Phi(block, arity, phi_in, mode_M,
 185                                        arch_no_register_req);
 186         sched_add_after(block, spill_info->spill);
 187
 188         if (spill_to_kill != NULL) {
 189                 exchange(spill_to_kill, spill_info->spill);
 190                 sched_remove(spill_to_kill);
 191         }
 192
 193         /* create spills for the phi values */
 194         for (i = 0; i < arity; ++i) {
 195                 ir_node *in = get_irn_n(phi, i);
 196                 spill_info_t *pred_spill = create_spill(env, in, 1);
 197                 set_irn_n(spill_info->spill, i, pred_spill->spill);
 198         }
 199 }
 200
 201 static void belady(minibelady_env_t *env, ir_node *block);
 202
 203 /**
 204  * Collects all values live-in at block @p block and all phi results in this
 205  * block.
 206  * Then it adds the best values (at most n_regs) to the blocks start_workset.
 207  * The phis among the remaining values get spilled: Introduce pseudo-copies of
 208  * their args to break interference and make it possible to spill them to the
 209  * same spill slot.
 210  */
 211 static block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
 212 {
 213         block_info_t  *block_info;
 214         be_next_use_t  next_use;
 215         ir_loop       *loop;
 216         ir_node       *best_starter, *first;
 217         int            n_cfgpreds;
 218         unsigned       best_time;
 219         int            outer_loop_allowed;
 220
 221         /* Create the block info for this block. */
 222         block_info = new_block_info(&env->obst, block);
 223         n_cfgpreds = get_Block_n_cfgpreds(block);
 224
 225         /* no cfgpred -> no value active */
 226         if (n_cfgpreds == 0) {
 227                 block_info->start_state = NULL;
 228                 return block_info;
 229         }
 230
 231         /* for 1 pred only: simply take the the end-state of the pred */
 232         if (n_cfgpreds == 1) {
 233                 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
 234                 block_info_t *pred_info;
 235
 236                 /* process pred block */
 237                 belady(env, pred_block);
 238
 239                 pred_info = get_block_info(pred_block);
 240
 241                 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
 242                 block_info->start_state = pred_info->end_state;
 243                 return block_info;
 244         }
 245
 246         /* Collect all values living at start of block */
 247         DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
 248         first = sched_first(block);
 249         loop = get_irn_loop(block);
 250         best_starter = NULL;
 251         best_time = USES_INFINITY;
 252         outer_loop_allowed = 1;
 253
 254         /* check all Phis first */
 255         sched_foreach(block, node) {
 256                 if (!is_Phi(node))
 257                         break;
 258                 if (arch_get_irn_register(node) != env->reg)
 259                         continue;
 260
 261                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 262                 next_use = be_get_next_use(env->uses, first, node, 0);
 263
 264                 if (USES_IS_INFINITE(next_use.time)) {
 265                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 266                         continue;
 267                 }
 268
 269                 if (next_use.outermost_loop >= get_loop_depth(loop)) {
 270                         if (outer_loop_allowed || next_use.time < best_time) {
 271                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 272                                      next_use.outermost_loop));
 273
 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                                 outer_loop_allowed = 0;
 281                         }
 282                 } else {
 283                         if (outer_loop_allowed && next_use.time < best_time) {
 284                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 285                                      next_use.outermost_loop));
 286                                 if (best_starter != NULL) {
 287                                         /* spill the phi as it is not used */
 288                                         spill_phi(env, best_starter);
 289                                 }
 290                                 best_starter = node;
 291                                 best_time = next_use.time;
 292                         }
 293                 }
 294
 295                 if (best_starter != node) {
 296                         /* spill the phi as it is not used */
 297                         spill_phi(env, best_starter);
 298                 }
 299         }
 300
 301         /* check all Live-Ins */
 302         be_lv_foreach(env->lv, block, be_lv_state_in, node) {
 303                 if (!mode_is_data(get_irn_mode(node)))
 304                         continue;
 305
 306                 if (arch_get_irn_register(node) != env->reg)
 307                         continue;
 308
 309                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 310                 next_use = be_get_next_use(env->uses, first, node, 0);
 311
 312                 if (USES_IS_INFINITE(next_use.time)) {
 313                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 314                         continue;
 315                 }
 316
 317                 if (next_use.outermost_loop >= get_loop_depth(loop)) {
 318                         if (outer_loop_allowed || next_use.time < best_time) {
 319                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 320                                      next_use.outermost_loop));
 321
 322                                 if (best_starter != NULL && is_Phi(best_starter)) {
 323                                         /* spill the phi as it is not used */
 324                                         spill_phi(env, best_starter);
 325                                 }
 326                                 best_starter = node;
 327                                 best_time = next_use.time;
 328                                 outer_loop_allowed = 0;
 329                         }
 330                 } else {
 331                         if (outer_loop_allowed && next_use.time < best_time) {
 332                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 333                                      next_use.outermost_loop));
 334                                 if (best_starter != NULL && is_Phi(best_starter)) {
 335                                         /* spill the phi as it is not used */
 336                                         spill_phi(env, best_starter);
 337                                 }
 338                                 best_starter = node;
 339                                 best_time = next_use.time;
 340                         }
 341                 }
 342         }
 343
 344         block_info->start_state = best_starter;
 345
 346         return block_info;
 347 }
 348
 349 /**
 350  * For the given block @p block, decide for each values
 351  * whether it is used from a register or is reloaded
 352  * before the use.
 353  */
 354 static void belady(minibelady_env_t *env, ir_node *block)
 355 {
 356         ir_node *current_state;
 357         block_info_t *block_info;
 358
 359         /* Don't do a block twice */
 360         if (irn_visited(block))
 361                 return;
 362
 363         /* compute value to start with */
 364         block_info = compute_block_start_state(env, block);
 365
 366         /* get the starting workset for this block */
 367         DBG((dbg, LEVEL_3, "\n"));
 368         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 369
 370         current_state = block_info->start_state;
 371         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 372
 373         /* process the block from start to end */
 374         DBG((dbg, LEVEL_3, "Processing...\n"));
 375
 376         sched_foreach(block, node) {
 377                 int i, arity;
 378                 ir_node *need_val = NULL;
 379
 380                 /* projs are handled with the tuple value.
 381                  * Phis are no real instr (see insert_starters()) */
 382                 if (is_Proj(node) || is_Phi(node)) {
 383                         continue;
 384                 }
 385
 386                 /* check which state is desired for the node */
 387                 arity = get_irn_arity(node);
 388                 for (i = 0; i < arity; ++i) {
 389                         const arch_register_t *reg;
 390                         ir_node *in = get_irn_n(node, i);
 391
 392                         if (!mode_is_data(get_irn_mode(in)))
 393                                 continue;
 394
 395                         reg = arch_get_irn_register(in);
 396                         if (reg == env->reg) {
 397                                 assert(need_val == NULL);
 398                                 need_val = in;
 399                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 400                         }
 401                 }
 402                 /* create a reload to match state if necessary */
 403                 if (need_val != NULL && need_val != current_state) {
 404                         ir_node *before = node;
 405                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 406                         create_reload(env, need_val, before, current_state);
 407                         current_state = need_val;
 408                 }
 409
 410                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 411
 412                 /* record state changes by the node */
 413                 if (get_irn_mode(node) == mode_T) {
 414                         foreach_out_edge(node, edge) {
 415                                 const arch_register_t *reg;
 416                                 ir_node *proj = get_edge_src_irn(edge);
 417
 418                                 if (!mode_is_data(get_irn_mode(proj)))
 419                                         continue;
 420
 421                                 reg = arch_get_irn_register(proj);
 422                                 if (reg == env->reg) {
 423                                         current_state = proj;
 424                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 425                                 }
 426                         }
 427                 } else {
 428                         if (mode_is_data(get_irn_mode(node))) {
 429                                 const arch_register_t *reg = arch_get_irn_register(node);
 430                                 if (reg == env->reg) {
 431                                         current_state = node;
 432                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 433                                 }
 434                         }
 435                 }
 436         }
 437
 438         /* Remember end-workset for this block */
 439         block_info->end_state = current_state;
 440         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 441 }
 442
 443 static void belady_walker(ir_node *block, void *data)
 444 {
 445         belady((minibelady_env_t*) data, block);
 446 }
 447
 448 static ir_node *get_end_of_block_insertion_point(ir_node *block)
 449 {
 450         ir_node *last = sched_last(block);
 451
 452         /* skip Projs and Keep-alikes behind the jump... */
 453         while (is_Proj(last) || be_is_Keep(last)) {
 454                 last = sched_prev(last);
 455         }
 456
 457         if (!is_cfop(last)) {
 458                 last = sched_next(last);
 459                 /* last node must be a cfop, only exception is the start block */
 460                 assert(last == get_irg_start_block(get_irn_irg(block)));
 461         }
 462
 463         return last;
 464 }
 465
 466 /**
 467  * We must adapt the live-outs to the live-ins at each block-border.
 468  */
 469 static void fix_block_borders(ir_node *block, void *data)
 470 {
 471         minibelady_env_t *env = (minibelady_env_t*)data;
 472         ir_graph *irg = get_irn_irg(block);
 473         ir_node *startblock = get_irg_start_block(irg);
 474         int i;
 475         int arity;
 476         block_info_t *block_info;
 477
 478         if (block == startblock)
 479                 return;
 480
 481         DBG((dbg, LEVEL_3, "\n"));
 482
 483         block_info = get_block_info(block);
 484
 485         DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
 486              block_info->start_state));
 487
 488         /* process all pred blocks */
 489         arity = get_irn_arity(block);
 490         for (i = 0; i < arity; ++i) {
 491                 ir_node      *pred       = get_Block_cfgpred_block(block, i);
 492                 block_info_t *pred_info  = get_block_info(pred);
 493                 ir_node      *need_state = block_info->start_state;
 494
 495                 if (need_state == NULL)
 496                         continue;
 497
 498                 if (is_Phi(need_state) && get_nodes_block(need_state) == block) {
 499                         need_state = get_irn_n(need_state, i);
 500                 }
 501
 502                 DBG((dbg, LEVEL_3, "  Pred %+F (ends in %+F, we need %+F)\n", pred,
 503                      pred_info->end_state, need_state));
 504
 505                 if (pred_info->end_state != need_state) {
 506                         ir_node *insert_point = get_end_of_block_insertion_point(pred);
 507
 508
 509                         DBG((dbg, LEVEL_3, "  Creating reload for %+F\n", need_state));
 510                         create_reload(env, need_state, insert_point, pred_info->end_state);
 511                 }
 512         }
 513 }
 514
 515 void be_assure_state(ir_graph *irg, const arch_register_t *reg, void *func_env,
 516                      create_spill_func create_spill,
 517                      create_reload_func create_reload)
 518 {
 519         minibelady_env_t env;
 520         spill_info_t *info;
 521         be_lv_t *lv = be_get_irg_liveness(irg);
 522
 523         be_assure_live_sets(irg);
 524         assure_loopinfo(irg);
 525
 526         obstack_init(&env.obst);
 527         env.reg           = reg;
 528         env.func_env      = func_env;
 529         env.create_spill  = create_spill;
 530         env.create_reload = create_reload;
 531         env.lv            = be_get_irg_liveness(irg);
 532         env.uses          = be_begin_uses(irg, env.lv);
 533         env.spills        = NULL;
 534         ir_nodehashmap_init(&env.spill_infos);
 535
 536         assure_doms(irg);
 537         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 538         inc_irg_visited(irg);
 539
 540         /* process blocks */
 541         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 542
 543         /* fix block end_states that don't match the next blocks start_state */
 544         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 545
 546         ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 547
 548         /* reconstruct ssa-form */
 549         info = env.spills;
 550         while (info != NULL) {
 551                 be_ssa_construction_env_t senv;
 552                 size_t i, len;
 553                 ir_node **phis;
 554
 555                 be_ssa_construction_init(&senv, irg);
 556                 if (sched_is_scheduled(info->value))
 557                         be_ssa_construction_add_copy(&senv, info->value);
 558                 be_ssa_construction_add_copies(&senv,
 559                                                info->reloads, ARR_LEN(info->reloads));
 560                 be_ssa_construction_fix_users(&senv, info->value);
 561
 562                 if (lv != NULL) {
 563                         be_ssa_construction_update_liveness_phis(&senv, lv);
 564
 565                         be_liveness_update(lv, info->value);
 566                         len = ARR_LEN(info->reloads);
 567                         for (i = 0; i < len; ++i) {
 568                                 ir_node *reload = info->reloads[i];
 569                                 be_liveness_update(lv, reload);
 570                         }
 571                 }
 572
 573                 phis = be_ssa_construction_get_new_phis(&senv);
 574
 575                 /* set register requirements for phis */
 576                 len = ARR_LEN(phis);
 577                 for (i = 0; i < len; ++i) {
 578                         ir_node *phi = phis[i];
 579                         arch_set_irn_register(phi, env.reg);
 580                 }
 581                 be_ssa_construction_destroy(&senv);
 582
 583                 info = info->next;
 584         }
 585
 586         /* some nodes might be dead now. */
 587         be_remove_dead_nodes_from_schedule(irg);
 588
 589         ir_nodehashmap_destroy(&env.spill_infos);
 590         be_end_uses(env.uses);
 591         obstack_free(&env.obst, NULL);
 592 }
 593
 594 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state)
 595 void be_init_state(void)
 596 {
 597         FIRM_DBG_REGISTER(dbg, "firm.be.state");
 598 }