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         } else {
 140                 after = state;
 141         }
 142         spill_info->spill = env->create_spill(env->func_env, state, force, after);
 143
 144         return spill_info;
 145 }
 146
 147 static void create_reload(minibelady_env_t *env, ir_node *state,
 148                           ir_node *before, ir_node *last_state)
 149 {
 150         spill_info_t *spill_info = create_spill(env, state, 0);
 151         ir_node *spill = spill_info->spill;
 152         ir_node *reload;
 153
 154         reload = env->create_reload(env->func_env, state, spill, before,
 155                                     last_state);
 156         ARR_APP1(ir_node*, spill_info->reloads, reload);
 157 }
 158
 159 static void spill_phi(minibelady_env_t *env, ir_node *phi)
 160 {
 161         ir_graph     *irg           = get_irn_irg(phi);
 162         ir_node      *block         = get_nodes_block(phi);
 163         int           arity         = get_irn_arity(phi);
 164         ir_node     **phi_in        = ALLOCAN(ir_node*, arity);
 165         ir_node      *dummy         = new_r_Dummy(irg, mode_M);
 166         ir_node      *spill_to_kill = NULL;
 167         spill_info_t *spill_info;
 168         int           i;
 169
 170         /* does a spill exist for the phis value? */
 171         spill_info = get_spill_info(env, phi);
 172         if (spill_info != NULL) {
 173                 spill_to_kill = spill_info->spill;
 174         } else {
 175                 spill_info = create_spill_info(env, phi);
 176         }
 177
 178         /* create a new phi-M with bad preds */
 179         for (i = 0; i < arity; ++i) {
 180                 phi_in[i] = dummy;
 181         }
 182
 183         DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
 184
 185         /* create a Phi-M */
 186         spill_info->spill = be_new_Phi(block, arity, phi_in, mode_M, NULL);
 187         sched_add_after(block, spill_info->spill);
 188
 189         if (spill_to_kill != NULL) {
 190                 exchange(spill_to_kill, spill_info->spill);
 191                 sched_remove(spill_to_kill);
 192         }
 193
 194         /* create spills for the phi values */
 195         for (i = 0; i < arity; ++i) {
 196                 ir_node *in = get_irn_n(phi, i);
 197                 spill_info_t *pred_spill = create_spill(env, in, 1);
 198                 set_irn_n(spill_info->spill, i, pred_spill->spill);
 199         }
 200 }
 201
 202 static void belady(minibelady_env_t *env, ir_node *block);
 203
 204 /**
 205  * Collects all values live-in at block @p block and all phi results in this
 206  * block.
 207  * Then it adds the best values (at most n_regs) to the blocks start_workset.
 208  * The phis among the remaining values get spilled: Introduce pseudo-copies of
 209  * their args to break interference and make it possible to spill them to the
 210  * same spill slot.
 211  */
 212 static block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
 213 {
 214         block_info_t  *block_info;
 215         be_next_use_t  next_use;
 216         ir_loop       *loop;
 217         ir_node       *best_starter, *first;
 218         ir_node       *node;
 219         int            n_cfgpreds;
 220         unsigned       best_time;
 221         int            outer_loop_allowed;
 222         int            i;
 223
 224         /* Create the block info for this block. */
 225         block_info = new_block_info(&env->obst, block);
 226         n_cfgpreds = get_Block_n_cfgpreds(block);
 227
 228         /* no cfgpred -> no value active */
 229         if (n_cfgpreds == 0) {
 230                 block_info->start_state = NULL;
 231                 return block_info;
 232         }
 233
 234         /* for 1 pred only: simply take the the end-state of the pred */
 235         if (n_cfgpreds == 1) {
 236                 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
 237                 block_info_t *pred_info;
 238
 239                 /* process pred block */
 240                 belady(env, pred_block);
 241
 242                 pred_info = get_block_info(pred_block);
 243
 244                 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
 245                 block_info->start_state = pred_info->end_state;
 246                 return block_info;
 247         }
 248
 249         /* Collect all values living at start of block */
 250         DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
 251         first = sched_first(block);
 252         loop = get_irn_loop(block);
 253         best_starter = NULL;
 254         best_time = USES_INFINITY;
 255         outer_loop_allowed = 1;
 256
 257         /* check all Phis first */
 258         sched_foreach(block, node) {
 259                 if (!is_Phi(node))
 260                         break;
 261                 if (arch_get_irn_register(node) != env->reg)
 262                         continue;
 263
 264                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 265                 next_use = be_get_next_use(env->uses, first, node, 0);
 266
 267                 if (USES_IS_INFINITE(next_use.time)) {
 268                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 269                         continue;
 270                 }
 271
 272                 if (next_use.outermost_loop >= get_loop_depth(loop)) {
 273                         if (outer_loop_allowed || next_use.time < best_time) {
 274                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 275                                      next_use.outermost_loop));
 276
 277                                 if (best_starter != NULL) {
 278                                         /* spill the phi as it is not used */
 279                                         spill_phi(env, best_starter);
 280                                 }
 281                                 best_starter = node;
 282                                 best_time = next_use.time;
 283                                 outer_loop_allowed = 0;
 284                         }
 285                 } else {
 286                         if (outer_loop_allowed && next_use.time < best_time) {
 287                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 288                                      next_use.outermost_loop));
 289                                 if (best_starter != NULL) {
 290                                         /* spill the phi as it is not used */
 291                                         spill_phi(env, best_starter);
 292                                 }
 293                                 best_starter = node;
 294                                 best_time = next_use.time;
 295                         }
 296                 }
 297
 298                 if (best_starter != node) {
 299                         /* spill the phi as it is not used */
 300                         spill_phi(env, best_starter);
 301                 }
 302         }
 303
 304         /* check all Live-Ins */
 305         be_lv_foreach(env->lv, block, be_lv_state_in, i) {
 306                 node = be_lv_get_irn(env->lv, block, i);
 307
 308                 if (!mode_is_data(get_irn_mode(node)))
 309                         continue;
 310
 311                 if (arch_get_irn_register(node) != env->reg)
 312                         continue;
 313
 314                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 315                 next_use = be_get_next_use(env->uses, first, node, 0);
 316
 317                 if (USES_IS_INFINITE(next_use.time)) {
 318                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 319                         continue;
 320                 }
 321
 322                 if (next_use.outermost_loop >= get_loop_depth(loop)) {
 323                         if (outer_loop_allowed || next_use.time < best_time) {
 324                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 325                                      next_use.outermost_loop));
 326
 327                                 if (best_starter != NULL && is_Phi(best_starter)) {
 328                                         /* spill the phi as it is not used */
 329                                         spill_phi(env, best_starter);
 330                                 }
 331                                 best_starter = node;
 332                                 best_time = next_use.time;
 333                                 outer_loop_allowed = 0;
 334                         }
 335                 } else {
 336                         if (outer_loop_allowed && next_use.time < best_time) {
 337                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 338                                      next_use.outermost_loop));
 339                                 if (best_starter != NULL && is_Phi(best_starter)) {
 340                                         /* spill the phi as it is not used */
 341                                         spill_phi(env, best_starter);
 342                                 }
 343                                 best_starter = node;
 344                                 best_time = next_use.time;
 345                         }
 346                 }
 347         }
 348
 349         block_info->start_state = best_starter;
 350
 351         return block_info;
 352 }
 353
 354 /**
 355  * For the given block @p block, decide for each values
 356  * whether it is used from a register or is reloaded
 357  * before the use.
 358  */
 359 static void belady(minibelady_env_t *env, ir_node *block)
 360 {
 361         ir_node *current_state;
 362         ir_node *node;
 363         block_info_t *block_info;
 364
 365         /* Don't do a block twice */
 366         if (irn_visited(block))
 367                 return;
 368
 369         /* compute value to start with */
 370         block_info = compute_block_start_state(env, block);
 371
 372         /* get the starting workset for this block */
 373         DBG((dbg, LEVEL_3, "\n"));
 374         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 375
 376         current_state = block_info->start_state;
 377         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 378
 379         /* process the block from start to end */
 380         DBG((dbg, LEVEL_3, "Processing...\n"));
 381
 382         sched_foreach(block, node) {
 383                 int i, arity;
 384                 ir_node *need_val = NULL;
 385
 386                 /* projs are handled with the tuple value.
 387                  * Phis are no real instr (see insert_starters()) */
 388                 if (is_Proj(node) || is_Phi(node)) {
 389                         continue;
 390                 }
 391
 392                 /* check which state is desired for the node */
 393                 arity = get_irn_arity(node);
 394                 for (i = 0; i < arity; ++i) {
 395                         const arch_register_t *reg;
 396                         ir_node *in = get_irn_n(node, i);
 397
 398                         if (!mode_is_data(get_irn_mode(in)))
 399                                 continue;
 400
 401                         reg = arch_get_irn_register(in);
 402                         if (reg == env->reg) {
 403                                 assert(need_val == NULL);
 404                                 need_val = in;
 405                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 406                         }
 407                 }
 408                 /* create a reload to match state if necessary */
 409                 if (need_val != NULL && need_val != current_state) {
 410                         ir_node *before = node;
 411                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 412                         create_reload(env, need_val, before, current_state);
 413                         current_state = need_val;
 414                 }
 415
 416                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 417
 418                 /* record state changes by the node */
 419                 if (get_irn_mode(node) == mode_T) {
 420                         const ir_edge_t *edge;
 421
 422                         foreach_out_edge(node, edge) {
 423                                 const arch_register_t *reg;
 424                                 ir_node *proj = get_edge_src_irn(edge);
 425
 426                                 if (!mode_is_data(get_irn_mode(proj)))
 427                                         continue;
 428
 429                                 reg = arch_get_irn_register(proj);
 430                                 if (reg == env->reg) {
 431                                         current_state = proj;
 432                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 433                                 }
 434                         }
 435                 } else {
 436                         if (mode_is_data(get_irn_mode(node))) {
 437                                 const arch_register_t *reg = arch_get_irn_register(node);
 438                                 if (reg == env->reg) {
 439                                         current_state = node;
 440                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 441                                 }
 442                         }
 443                 }
 444         }
 445
 446         /* Remember end-workset for this block */
 447         block_info->end_state = current_state;
 448         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 449 }
 450
 451 static void belady_walker(ir_node *block, void *data)
 452 {
 453         belady((minibelady_env_t*) data, block);
 454 }
 455
 456 static ir_node *get_end_of_block_insertion_point(ir_node *block)
 457 {
 458         ir_node *last = sched_last(block);
 459
 460         /* skip Projs and Keep-alikes behind the jump... */
 461         while (is_Proj(last) || be_is_Keep(last)) {
 462                 last = sched_prev(last);
 463         }
 464
 465         if (!is_cfop(last)) {
 466                 last = sched_next(last);
 467                 /* last node must be a cfop, only exception is the start block */
 468                 assert(last == get_irg_start_block(get_irn_irg(block)));
 469         }
 470
 471         return last;
 472 }
 473
 474 /**
 475  * We must adapt the live-outs to the live-ins at each block-border.
 476  */
 477 static void fix_block_borders(ir_node *block, void *data)
 478 {
 479         minibelady_env_t *env = (minibelady_env_t*)data;
 480         ir_graph *irg = get_irn_irg(block);
 481         ir_node *startblock = get_irg_start_block(irg);
 482         int i;
 483         int arity;
 484         block_info_t *block_info;
 485
 486         if (block == startblock)
 487                 return;
 488
 489         DBG((dbg, LEVEL_3, "\n"));
 490
 491         block_info = get_block_info(block);
 492
 493         DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
 494              block_info->start_state));
 495
 496         /* process all pred blocks */
 497         arity = get_irn_arity(block);
 498         for (i = 0; i < arity; ++i) {
 499                 ir_node      *pred       = get_Block_cfgpred_block(block, i);
 500                 block_info_t *pred_info  = get_block_info(pred);
 501                 ir_node      *need_state = block_info->start_state;
 502
 503                 if (need_state == NULL)
 504                         continue;
 505
 506                 if (is_Phi(need_state) && get_nodes_block(need_state) == block) {
 507                         need_state = get_irn_n(need_state, i);
 508                 }
 509
 510                 DBG((dbg, LEVEL_3, "  Pred %+F (ends in %+F, we need %+F)\n", pred,
 511                      pred_info->end_state, need_state));
 512
 513                 if (pred_info->end_state != need_state) {
 514                         ir_node *insert_point = get_end_of_block_insertion_point(pred);
 515
 516
 517                         DBG((dbg, LEVEL_3, "  Creating reload for %+F\n", need_state));
 518                         create_reload(env, need_state, insert_point, pred_info->end_state);
 519                 }
 520         }
 521 }
 522
 523 void be_assure_state(ir_graph *irg, const arch_register_t *reg, void *func_env,
 524                      create_spill_func create_spill,
 525                      create_reload_func create_reload)
 526 {
 527         minibelady_env_t env;
 528         spill_info_t *info;
 529         be_lv_t *lv = be_assure_liveness(irg);
 530
 531         be_liveness_assure_sets(lv);
 532         /* construct control flow loop tree */
 533         if (! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
 534                 construct_cf_backedges(irg);
 535         }
 536
 537         obstack_init(&env.obst);
 538         env.reg           = reg;
 539         env.func_env      = func_env;
 540         env.create_spill  = create_spill;
 541         env.create_reload = create_reload;
 542         env.lv            = be_get_irg_liveness(irg);
 543         env.uses          = be_begin_uses(irg, env.lv);
 544         env.spills        = NULL;
 545         ir_nodemap_init(&env.spill_infos);
 546
 547         assure_doms(irg);
 548         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 549         inc_irg_visited(irg);
 550
 551         /* process blocks */
 552         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 553
 554         /* fix block end_states that don't match the next blocks start_state */
 555         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 556
 557         ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 558
 559         /* reconstruct ssa-form */
 560         info = env.spills;
 561         while (info != NULL) {
 562                 be_ssa_construction_env_t senv;
 563                 size_t i, len;
 564                 ir_node **phis;
 565
 566                 be_ssa_construction_init(&senv, irg);
 567                 if (sched_is_scheduled(info->value))
 568                         be_ssa_construction_add_copy(&senv, info->value);
 569                 be_ssa_construction_add_copies(&senv,
 570                                                info->reloads, ARR_LEN(info->reloads));
 571                 be_ssa_construction_fix_users(&senv, info->value);
 572
 573                 if (lv != NULL) {
 574                         be_ssa_construction_update_liveness_phis(&senv, lv);
 575
 576                         be_liveness_update(lv, info->value);
 577                         len = ARR_LEN(info->reloads);
 578                         for (i = 0; i < len; ++i) {
 579                                 ir_node *reload = info->reloads[i];
 580                                 be_liveness_update(lv, reload);
 581                         }
 582                 }
 583
 584                 phis = be_ssa_construction_get_new_phis(&senv);
 585
 586                 /* set register requirements for phis */
 587                 len = ARR_LEN(phis);
 588                 for (i = 0; i < len; ++i) {
 589                         ir_node *phi = phis[i];
 590                         arch_set_irn_register(phi, env.reg);
 591                 }
 592                 be_ssa_construction_destroy(&senv);
 593
 594                 info = info->next;
 595         }
 596
 597         /* some nodes might be dead now. */
 598         be_remove_dead_nodes_from_schedule(irg);
 599
 600         ir_nodemap_destroy(&env.spill_infos);
 601         be_end_uses(env.uses);
 602         obstack_free(&env.obst, NULL);
 603 }
 604
 605 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state)
 606 void be_init_state(void)
 607 {
 608         FIRM_DBG_REGISTER(dbg, "firm.be.state");
 609 }