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