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

   1 /*
   2  * Copyright (C) 1995-2007 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 #ifdef HAVE_CONFIG_H
  29 #include "config.h"
  30 #endif
  31
  32 #include "bestate.h"
  33
  34 #include "obst.h"
  35 #include "irgraph_t.h"
  36 #include "irnode_t.h"
  37 #include "irgwalk.h"
  38 #include "irloop.h"
  39 #include "iredges_t.h"
  40 #include "ircons_t.h"
  41 #include "irgmod.h"
  42
  43 #include "bearch_t.h"
  44 #include "beuses.h"
  45 #include "besched_t.h"
  46 #include "belive_t.h"
  47 #include "bemodule.h"
  48 #include "benode_t.h"
  49 #include "bessaconstr.h"
  50
  51 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  52
  53 typedef struct spill_info_t {
  54         struct spill_info_t *next;
  55         ir_node *value;
  56         ir_node *spill;
  57         ir_node **reloads;
  58 } spill_info_t;
  59
  60 typedef struct minibelady_env_t {
  61         struct obstack         obst;
  62         const arch_env_t      *arch_env;
  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
  70         be_uses_t             *uses;           /**< env for the next-use magic */
  71 } minibelady_env_t;
  72
  73 typedef struct block_info_t {
  74         ir_node *start_state;
  75         ir_node *end_state;
  76 } block_info_t;
  77
  78 static INLINE
  79 block_info_t *new_block_info(struct obstack *obst, ir_node *block)
  80 {
  81         block_info_t *res = obstack_alloc(obst, sizeof(*res));
  82         memset(res, 0, sizeof(res[0]));
  83
  84         set_irn_link(block, res);
  85         mark_irn_visited(block);
  86
  87         return res;
  88 }
  89
  90 static INLINE
  91 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
  98 spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
  99 {
 100         spill_info_t *spill_info = obstack_alloc(&env->obst, sizeof(spill_info[0]));
 101         memset(spill_info, 0, sizeof(spill_info[0]));
 102         spill_info->value = state;
 103         spill_info->reloads = NEW_ARR_F(ir_node*, 0);
 104
 105         set_irn_link(state, spill_info);
 106         mark_irn_visited(state);
 107
 108         spill_info->next = env->spills;
 109         env->spills = spill_info;
 110
 111         return spill_info;
 112 }
 113
 114 static
 115 spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
 116 {
 117         spill_info_t *spill_info;
 118         ir_node *next;
 119         ir_node *after;
 120
 121         if(irn_visited(state)) {
 122                 spill_info = (spill_info_t*) get_irn_link(state);
 123                 if(spill_info->spill != NULL || !force)
 124                         return spill_info;
 125         } else {
 126                 spill_info = create_spill_info(env, state);
 127         }
 128
 129         if(sched_is_scheduled(state)) {
 130                 next = state;
 131                 do {
 132                         after = next;
 133                         next = sched_next(after);
 134                 } while(is_Proj(next) || is_Phi(next) || be_is_Keep(next));
 135         } else {
 136                 after = state;
 137         }
 138         spill_info->spill = env->create_spill(env->func_env, state, force, after);
 139
 140         return spill_info;
 141 }
 142
 143 static
 144 void create_reload(minibelady_env_t *env, ir_node *state, ir_node *before,
 145                    ir_node *last_state)
 146 {
 147         spill_info_t *spill_info = create_spill(env, state, 0);
 148         ir_node *spill = spill_info->spill;
 149         ir_node *reload;
 150
 151         reload = env->create_reload(env->func_env, state, spill, before,
 152                                     last_state);
 153         ARR_APP1(ir_node*, spill_info->reloads, reload);
 154 }
 155
 156 static
 157 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 i, arity = get_irn_arity(phi);
 162         ir_node **in = alloca(arity * sizeof(in[0]));
 163         ir_node *spill_to_kill = NULL;
 164         spill_info_t *spill_info;
 165
 166         /* does a spill exist for the phis value? */
 167         if(irn_visited(phi)) {
 168                 spill_info = (spill_info_t*) get_irn_link(phi);
 169                 spill_to_kill = spill_info->spill;
 170         } else {
 171                 spill_info = create_spill_info(env, phi);
 172         }
 173
 174         /* create a new phi-M with bad preds */
 175         for(i = 0; i < arity; ++i) {
 176                 in[i] = new_r_Bad(irg);
 177         }
 178
 179         DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
 180
 181         /* create a Phi-M */
 182         spill_info->spill = new_r_Phi(irg, block, arity, in, mode_M);
 183
 184         if(spill_to_kill != NULL) {
 185                 exchange(spill_to_kill, spill_info->spill);
 186                 sched_remove(spill_to_kill);
 187         }
 188
 189         /* create spills for the phi values */
 190         for(i = 0; i < arity; ++i) {
 191                 ir_node *in = get_irn_n(phi, i);
 192                 spill_info_t *pred_spill = create_spill(env, in, 1);
 193                 set_irn_n(spill_info->spill, i, pred_spill->spill);
 194         }
 195 }
 196
 197 static
 198 void belady(minibelady_env_t *env, ir_node *block);
 199
 200 /**
 201  * Collects all values live-in at block @p block and all phi results in this
 202  * block.
 203  * Then it adds the best values (at most n_regs) to the blocks start_workset.
 204  * The phis among the remaining values get spilled: Introduce psudo-copies of
 205  * their args to break interference and make it possible to spill them to the
 206  * same spill slot.
 207  */
 208 static
 209 block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
 210 {
 211         block_info_t  *block_info;
 212         be_next_use_t  next_use;
 213         ir_loop       *loop;
 214         ir_node       *best_starter, *first;
 215         ir_node       *node;
 216         int            n_cfgpreds;
 217         unsigned       best_time;
 218         int            outer_loop_allowed;
 219         int            i;
 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(env->arch_env, 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, 0, 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, i) {
 303                 node = be_lv_get_irn(env->lv, block, i);
 304
 305                 if (arch_get_irn_register(env->arch_env, node) != env->reg)
 306                         continue;
 307
 308                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 309                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 310
 311                 if(USES_IS_INFINITE(next_use.time)) {
 312                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 313                         continue;
 314                 }
 315
 316                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 317                         if(outer_loop_allowed || next_use.time < best_time) {
 318                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 319                                      next_use.outermost_loop));
 320
 321                                 if(best_starter != NULL && is_Phi(best_starter)) {
 322                                         /* spill the phi as it is not used */
 323                                         spill_phi(env, best_starter);
 324                                 }
 325                                 best_starter = node;
 326                                 best_time = next_use.time;
 327                                 outer_loop_allowed = 0;
 328                         }
 329                 } else {
 330                         if(outer_loop_allowed && next_use.time < best_time) {
 331                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 332                                      next_use.outermost_loop));
 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                         }
 340                 }
 341         }
 342
 343         block_info->start_state = best_starter;
 344
 345         return block_info;
 346 }
 347
 348 /**
 349  * For the given block @p block, decide for each values
 350  * whether it is used from a register or is reloaded
 351  * before the use.
 352  */
 353 static
 354 void belady(minibelady_env_t *env, ir_node *block)
 355 {
 356         ir_node *current_state;
 357         ir_node *node;
 358         block_info_t *block_info;
 359
 360         /* Don't do a block twice */
 361         if(irn_visited(block))
 362                 return;
 363
 364         /* compute value to start with */
 365         block_info = compute_block_start_state(env, block);
 366
 367         /* get the starting workset for this block */
 368         DBG((dbg, LEVEL_3, "\n"));
 369         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 370
 371         current_state = block_info->start_state;
 372         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 373
 374         /* process the block from start to end */
 375         DBG((dbg, LEVEL_3, "Processing...\n"));
 376
 377         sched_foreach(block, node) {
 378                 int i, arity;
 379                 ir_node *need_val = NULL;
 380
 381                 /* projs are handled with the tuple value.
 382                  * Phis are no real instr (see insert_starters()) */
 383                 if (is_Proj(node) || is_Phi(node)) {
 384                         continue;
 385                 }
 386
 387                 /* check which state is desired for the node */
 388                 arity = get_irn_arity(node);
 389                 for(i = 0; i < arity; ++i) {
 390                         ir_node *in = get_irn_n(node, i);
 391                         const arch_register_t *reg =
 392                                 arch_get_irn_register(env->arch_env, in);
 393                         if(reg == env->reg) {
 394                                 assert(need_val == NULL);
 395                                 need_val = in;
 396                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 397                         }
 398                 }
 399                 /* create a reload to match state if necessary */
 400                 if(need_val != NULL && need_val != current_state) {
 401                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 402                         create_reload(env, need_val, node, current_state);
 403                         current_state = need_val;
 404                 }
 405
 406                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 407
 408                 /* record state changes by the node */
 409                 if (get_irn_mode(node) == mode_T) {
 410                         ir_node *proj;
 411                         for(proj = sched_next(node); is_Proj(proj);
 412                             proj = sched_next(proj)) {
 413                                 const arch_register_t *reg =
 414                                         arch_get_irn_register(env->arch_env, proj);
 415                                 if(reg == env->reg) {
 416                                         current_state = proj;
 417                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 418                                 }
 419                         }
 420                 } else {
 421                         const arch_register_t *reg =
 422                                 arch_get_irn_register(env->arch_env, node);
 423                         if(reg == env->reg) {
 424                                 current_state = node;
 425                                 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 426                         }
 427                 }
 428         }
 429
 430         /* Remember end-workset for this block */
 431         block_info->end_state = current_state;
 432         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 433 }
 434
 435 static
 436 void belady_walker(ir_node *block, void *data)
 437 {
 438         belady((minibelady_env_t*) data, block);
 439 }
 440
 441 static
 442 ir_node *get_end_of_block_insertion_point(ir_node *block)
 443 {
 444         ir_node *last = sched_last(block);
 445
 446         /* skip projs and keepanies behind the jump... */
 447         while(is_Proj(last) || be_is_Keep(last)) {
 448                 last = sched_prev(last);
 449         }
 450
 451         if(!is_cfop(last)) {
 452                 last = sched_next(last);
 453                 // last node must be a cfop, only exception is the start block
 454                 assert(last     == get_irg_start_block(get_irn_irg(block)));
 455         }
 456
 457         return last;
 458 }
 459
 460 /**
 461  * We must adapt the live-outs to the live-ins at each block-border.
 462  */
 463 static
 464 void fix_block_borders(ir_node *block, void *data) {
 465         minibelady_env_t *env = data;
 466         ir_graph *irg = get_irn_irg(block);
 467         ir_node *startblock = get_irg_start_block(irg);
 468         int i;
 469         int arity;
 470         block_info_t *block_info;
 471
 472         if(block == startblock)
 473                 return;
 474
 475         DBG((dbg, LEVEL_3, "\n"));
 476         DBG((dbg, LEVEL_3, "Fixing %+F\n", block));
 477
 478         block_info = get_block_info(block);
 479
 480         /* process all pred blocks */
 481         arity = get_irn_arity(block);
 482         for (i = 0; i < arity; ++i) {
 483                 ir_node *pred = get_Block_cfgpred_block(block, i);
 484                 block_info_t *pred_info = get_block_info(pred);
 485
 486                 DBG((dbg, LEVEL_3, "  Pred %+F\n", pred));
 487
 488                 if(pred_info->end_state != block_info->start_state &&
 489                         block_info->start_state != NULL) {
 490                         ir_node *need_state = block_info->start_state;
 491                         ir_node *insert_point =
 492                                 get_end_of_block_insertion_point(pred);
 493
 494                         create_reload(env, need_state, insert_point, pred_info->end_state);
 495                 }
 496         }
 497 }
 498
 499 void be_assure_state(be_irg_t *birg, const arch_register_t *reg, void *func_env,
 500                      create_spill_func create_spill,
 501                      create_reload_func create_reload) {
 502         minibelady_env_t env;
 503         ir_graph *irg = be_get_birg_irg(birg);
 504         spill_info_t *info;
 505         be_lv_t *lv = be_get_birg_liveness(birg);
 506
 507         be_assure_liveness(birg);
 508         be_assure_dom_front(birg);
 509         /* construct control flow loop tree */
 510         if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
 511                 construct_cf_backedges(irg);
 512         }
 513
 514         obstack_init(&env.obst);
 515         env.arch_env      = be_get_birg_arch_env(birg);
 516         env.reg           = reg;
 517         env.func_env      = func_env;
 518         env.create_spill  = create_spill;
 519         env.create_reload = create_reload;
 520         env.lv            = be_get_birg_liveness(birg);
 521         env.uses          = be_begin_uses(irg, env.lv);
 522         env.spills        = NULL;
 523
 524         set_using_visited(irg);
 525         set_using_irn_link(irg);
 526         inc_irg_visited(irg);
 527
 528         /* process blocks */
 529         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 530
 531         /* fix block end_states that don't match the next blocks start_state */
 532         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 533
 534         clear_using_visited(irg);
 535         clear_using_irn_link(irg);
 536
 537         /* reconstruct ssa-form */
 538         info = env.spills;
 539         while(info != NULL) {
 540                 be_ssa_construction_env_t senv;
 541                 int i, len;
 542                 ir_node **phis;
 543
 544                 be_ssa_construction_init(&senv, birg);
 545                 if(sched_is_scheduled(info->value))
 546                         be_ssa_construction_add_copy(&senv, info->value);
 547                 be_ssa_construction_add_copies(&senv,
 548                                                info->reloads, ARR_LEN(info->reloads));
 549                 be_ssa_construction_fix_users(&senv, info->value);
 550
 551                 if(lv != NULL) {
 552                         be_ssa_construction_update_liveness_phis(&senv, lv);
 553
 554                         be_liveness_update(lv, info->value);
 555                         len = ARR_LEN(info->reloads);
 556                         for(i = 0; i < len; ++i) {
 557                                 ir_node *reload = info->reloads[i];
 558                                 be_liveness_update(lv, reload);
 559                         }
 560                 }
 561
 562                 phis = be_ssa_construction_get_new_phis(&senv);
 563
 564                 /* set register requirements for phis */
 565                 len = ARR_LEN(phis);
 566                 for(i = 0; i < len; ++i) {
 567                         ir_node *phi = phis[i];
 568                         be_set_phi_flags(env.arch_env, phi, arch_irn_flags_ignore);
 569                         arch_set_irn_register(env.arch_env, phi, env.reg);
 570                 }
 571                 be_ssa_construction_destroy(&senv);
 572
 573                 info = info->next;
 574         }
 575
 576         /* some nodes might be dead now. */
 577         be_remove_dead_nodes_from_schedule(irg);
 578
 579         be_end_uses(env.uses);
 580         obstack_free(&env.obst, NULL);
 581 }
 582
 583 void be_init_state(void)
 584 {
 585         FIRM_DBG_REGISTER(dbg, "firm.be.state");
 586 }
 587
 588 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);