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

   1 /*
   2  * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
   3  *
   4  * This file is part of libFirm.
   5  *
   6  * This file may be distributed and/or modified under the terms of the
   7  * GNU General Public License version 2 as published by the Free Software
   8  * Foundation and appearing in the file LICENSE.GPL included in the
   9  * packaging of this file.
  10  *
  11  * Licensees holding valid libFirm Professional Edition licenses may use
  12  * this file in accordance with the libFirm Commercial License.
  13  * Agreement provided with the Software.
  14  *
  15  * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
  16  * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  17  * PURPOSE.
  18  */
  19
  20 /**
  21  * @file
  22  * @brief       Handles state switching. This is basically the belady spill
  23  *              algorithm optimized for the 1-register case.
  24  * @author      Matthias Braun
  25  * @date        26.03.2007
  26  * @version     $Id$
  27  */
  28 #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 #include "irnodeset.h"
  43 #include "irnodemap.h"
  44 #include "adt/cpset.h"
  45
  46 #include "bearch_t.h"
  47 #include "beuses.h"
  48 #include "besched_t.h"
  49 #include "belive_t.h"
  50 #include "bemodule.h"
  51 #include "benode_t.h"
  52 #include "bessaconstr.h"
  53
  54 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  55
  56 typedef struct spill_info_t {
  57         struct spill_info_t *next;
  58         ir_node *value;
  59         ir_node *spill;
  60         ir_node **reloads;
  61 } spill_info_t;
  62
  63 typedef struct minibelady_env_t {
  64         struct obstack         obst;
  65         const arch_register_t *reg;
  66         const be_lv_t         *lv;
  67         void                  *func_env;
  68         create_reload_func     create_reload;
  69         create_spill_func      create_spill;
  70         spill_info_t          *spills;
  71         ir_nodemap_t           spill_infos;
  72
  73         be_uses_t             *uses;           /**< env for the next-use magic */
  74 } minibelady_env_t;
  75
  76 typedef struct block_info_t {
  77         ir_node *start_state;
  78         ir_node *end_state;
  79 } block_info_t;
  80
  81 static INLINE
  82 block_info_t *new_block_info(struct obstack *obst, ir_node *block)
  83 {
  84         block_info_t *res = obstack_alloc(obst, sizeof(*res));
  85         memset(res, 0, sizeof(res[0]));
  86
  87         assert(is_Block(block));
  88         set_irn_link(block, res);
  89         mark_irn_visited(block);
  90
  91         return res;
  92 }
  93
  94 static INLINE
  95 block_info_t *get_block_info(ir_node *block)
  96 {
  97         assert(irn_visited(block));
  98         return (block_info_t*) get_irn_link(block);
  99 }
 100
 101 static INLINE
 102 spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
 103 {
 104         spill_info_t *spill_info = obstack_alloc(&env->obst, sizeof(spill_info[0]));
 105         memset(spill_info, 0, sizeof(spill_info[0]));
 106         spill_info->value = state;
 107         spill_info->reloads = NEW_ARR_F(ir_node*, 0);
 108
 109         ir_nodemap_insert(&env->spill_infos, state, spill_info);
 110         //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
 111
 112         spill_info->next = env->spills;
 113         env->spills = spill_info;
 114
 115         return spill_info;
 116 }
 117
 118 static INLINE
 119 spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
 120 {
 121         spill_info_t *spill_info
 122                 = (spill_info_t*) ir_nodemap_get(&env->spill_infos, node);
 123         //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
 124         return spill_info;
 125 }
 126
 127 static
 128 spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
 129 {
 130         spill_info_t *spill_info;
 131         ir_node *next;
 132         ir_node *after;
 133
 134         spill_info = get_spill_info(env, state);
 135         if(spill_info == NULL) {
 136                 spill_info = create_spill_info(env, state);
 137         } else if(spill_info->spill != NULL) {
 138                 return spill_info;
 139         }
 140
 141         if(sched_is_scheduled(state)) {
 142                 next = state;
 143                 do {
 144                         after = next;
 145                         next = sched_next(after);
 146                 } while(is_Proj(next) || is_Phi(next) || be_is_Keep(next));
 147         } else {
 148                 after = state;
 149         }
 150         spill_info->spill = env->create_spill(env->func_env, state, force, after);
 151
 152         return spill_info;
 153 }
 154
 155 static
 156 void create_reload(minibelady_env_t *env, ir_node *state, ir_node *before,
 157                    ir_node *last_state)
 158 {
 159         spill_info_t *spill_info = create_spill(env, state, 0);
 160         ir_node *spill = spill_info->spill;
 161         ir_node *reload;
 162
 163         reload = env->create_reload(env->func_env, state, spill, before,
 164                                     last_state);
 165         ARR_APP1(ir_node*, spill_info->reloads, reload);
 166 }
 167
 168 static
 169 void spill_phi(minibelady_env_t *env, ir_node *phi)
 170 {
 171         ir_graph *irg = get_irn_irg(phi);
 172         ir_node *block = get_nodes_block(phi);
 173         int i, arity = get_irn_arity(phi);
 174         ir_node **in = alloca(arity * sizeof(in[0]));
 175         ir_node *spill_to_kill = NULL;
 176         spill_info_t *spill_info;
 177
 178         /* does a spill exist for the phis value? */
 179         spill_info = get_spill_info(env, phi);
 180         if(spill_info != NULL) {
 181                 spill_to_kill = spill_info->spill;
 182         } else {
 183                 spill_info = create_spill_info(env, phi);
 184         }
 185
 186         /* create a new phi-M with bad preds */
 187         for(i = 0; i < arity; ++i) {
 188                 in[i] = new_r_Unknown(irg, mode_M);
 189         }
 190
 191         DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
 192
 193         /* create a Phi-M */
 194         spill_info->spill = new_r_Phi(irg, block, arity, in, mode_M);
 195
 196         if(spill_to_kill != NULL) {
 197                 exchange(spill_to_kill, spill_info->spill);
 198                 sched_remove(spill_to_kill);
 199         }
 200
 201         /* create spills for the phi values */
 202         for(i = 0; i < arity; ++i) {
 203                 ir_node *in = get_irn_n(phi, i);
 204                 spill_info_t *pred_spill = create_spill(env, in, 1);
 205                 set_irn_n(spill_info->spill, i, pred_spill->spill);
 206         }
 207 }
 208
 209 static
 210 void belady(minibelady_env_t *env, ir_node *block);
 211
 212 /**
 213  * Collects all values live-in at block @p block and all phi results in this
 214  * block.
 215  * Then it adds the best values (at most n_regs) to the blocks start_workset.
 216  * The phis among the remaining values get spilled: Introduce psudo-copies of
 217  * their args to break interference and make it possible to spill them to the
 218  * same spill slot.
 219  */
 220 static
 221 block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
 222 {
 223         block_info_t  *block_info;
 224         be_next_use_t  next_use;
 225         ir_loop       *loop;
 226         ir_node       *best_starter, *first;
 227         ir_node       *node;
 228         int            n_cfgpreds;
 229         unsigned       best_time;
 230         int            outer_loop_allowed;
 231         int            i;
 232
 233         /* Create the block info for this block. */
 234         block_info = new_block_info(&env->obst, block);
 235         n_cfgpreds = get_Block_n_cfgpreds(block);
 236
 237         /* no cfgpred -> no value active */
 238         if(n_cfgpreds == 0) {
 239                 block_info->start_state = NULL;
 240                 return block_info;
 241         }
 242
 243         /* for 1 pred only: simply take the the end-state of the pred */
 244         if(n_cfgpreds == 1) {
 245                 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
 246                 block_info_t *pred_info;
 247
 248                 /* process pred block */
 249                 belady(env, pred_block);
 250
 251                 pred_info = get_block_info(pred_block);
 252
 253                 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
 254                 block_info->start_state = pred_info->end_state;
 255                 return block_info;
 256         }
 257
 258         /* Collect all values living at start of block */
 259         DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
 260         first = sched_first(block);
 261         loop = get_irn_loop(block);
 262         best_starter = NULL;
 263         best_time = USES_INFINITY;
 264         outer_loop_allowed = 1;
 265
 266         /* check all Phis first */
 267         sched_foreach(block, node) {
 268                 if (!is_Phi(node))
 269                         break;
 270                 if (arch_get_irn_register(node) != env->reg)
 271                         continue;
 272
 273                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 274                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 275
 276                 if(USES_IS_INFINITE(next_use.time)) {
 277                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 278                         continue;
 279                 }
 280
 281                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 282                         if(outer_loop_allowed || next_use.time < best_time) {
 283                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 284                                      next_use.outermost_loop));
 285
 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                                 outer_loop_allowed = 0;
 293                         }
 294                 } else {
 295                         if(outer_loop_allowed && next_use.time < best_time) {
 296                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 297                                      next_use.outermost_loop));
 298                                 if(best_starter != NULL) {
 299                                         /* spill the phi as it is not used */
 300                                         spill_phi(env, best_starter);
 301                                 }
 302                                 best_starter = node;
 303                                 best_time = next_use.time;
 304                         }
 305                 }
 306
 307                 if(best_starter != node) {
 308                         /* spill the phi as it is not used */
 309                         spill_phi(env, best_starter);
 310                 }
 311         }
 312
 313         /* check all Live-Ins */
 314         be_lv_foreach(env->lv, block, be_lv_state_in, i) {
 315                 node = be_lv_get_irn(env->lv, block, i);
 316
 317                 if(!mode_is_data(get_irn_mode(node)))
 318                         continue;
 319
 320                 if (arch_get_irn_register(node) != env->reg)
 321                         continue;
 322
 323                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 324                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 325
 326                 if(USES_IS_INFINITE(next_use.time)) {
 327                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 328                         continue;
 329                 }
 330
 331                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 332                         if(outer_loop_allowed || next_use.time < best_time) {
 333                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 334                                      next_use.outermost_loop));
 335
 336                                 if(best_starter != NULL && is_Phi(best_starter)) {
 337                                         /* spill the phi as it is not used */
 338                                         spill_phi(env, best_starter);
 339                                 }
 340                                 best_starter = node;
 341                                 best_time = next_use.time;
 342                                 outer_loop_allowed = 0;
 343                         }
 344                 } else {
 345                         if(outer_loop_allowed && next_use.time < best_time) {
 346                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 347                                      next_use.outermost_loop));
 348                                 if(best_starter != NULL && is_Phi(best_starter)) {
 349                                         /* spill the phi as it is not used */
 350                                         spill_phi(env, best_starter);
 351                                 }
 352                                 best_starter = node;
 353                                 best_time = next_use.time;
 354                         }
 355                 }
 356         }
 357
 358         block_info->start_state = best_starter;
 359
 360         return block_info;
 361 }
 362
 363 /**
 364  * For the given block @p block, decide for each values
 365  * whether it is used from a register or is reloaded
 366  * before the use.
 367  */
 368 static
 369 void belady(minibelady_env_t *env, ir_node *block)
 370 {
 371         ir_node *current_state;
 372         ir_node *node;
 373         block_info_t *block_info;
 374
 375         /* Don't do a block twice */
 376         if(irn_visited(block))
 377                 return;
 378
 379         /* compute value to start with */
 380         block_info = compute_block_start_state(env, block);
 381
 382         /* get the starting workset for this block */
 383         DBG((dbg, LEVEL_3, "\n"));
 384         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 385
 386         current_state = block_info->start_state;
 387         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 388
 389         /* process the block from start to end */
 390         DBG((dbg, LEVEL_3, "Processing...\n"));
 391
 392         sched_foreach(block, node) {
 393                 int i, arity;
 394                 ir_node *need_val = NULL;
 395
 396                 /* projs are handled with the tuple value.
 397                  * Phis are no real instr (see insert_starters()) */
 398                 if (is_Proj(node) || is_Phi(node)) {
 399                         continue;
 400                 }
 401
 402                 /* check which state is desired for the node */
 403                 arity = get_irn_arity(node);
 404                 for(i = 0; i < arity; ++i) {
 405                         const arch_register_t *reg;
 406                         ir_node *in = get_irn_n(node, i);
 407
 408                         if(!mode_is_data(get_irn_mode(in)))
 409                                 continue;
 410
 411                         reg = arch_get_irn_register(in);
 412                         if(reg == env->reg) {
 413                                 assert(need_val == NULL);
 414                                 need_val = in;
 415                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 416                         }
 417                 }
 418                 /* create a reload to match state if necessary */
 419                 if(need_val != NULL && need_val != current_state) {
 420                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 421                         create_reload(env, need_val, node, current_state);
 422                         current_state = need_val;
 423                 }
 424
 425                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 426
 427                 /* record state changes by the node */
 428                 if (get_irn_mode(node) == mode_T) {
 429                         const ir_edge_t *edge;
 430
 431                         foreach_out_edge(node, edge) {
 432                                 const arch_register_t *reg;
 433                                 ir_node *proj = get_edge_src_irn(edge);
 434
 435                                 if(!mode_is_data(get_irn_mode(proj)))
 436                                         continue;
 437
 438                                 reg = arch_get_irn_register(proj);
 439                                 if(reg == env->reg) {
 440                                         current_state = proj;
 441                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 442                                 }
 443                         }
 444                 } else {
 445                         if(mode_is_data(get_irn_mode(node))) {
 446                                 const arch_register_t *reg = arch_get_irn_register(node);
 447                                 if(reg == env->reg) {
 448                                         current_state = node;
 449                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 450                                 }
 451                         }
 452                 }
 453         }
 454
 455         /* Remember end-workset for this block */
 456         block_info->end_state = current_state;
 457         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 458 }
 459
 460 static
 461 void belady_walker(ir_node *block, void *data)
 462 {
 463         belady((minibelady_env_t*) data, block);
 464 }
 465
 466 static
 467 ir_node *get_end_of_block_insertion_point(ir_node *block)
 468 {
 469         ir_node *last = sched_last(block);
 470
 471         /* skip Projs and Keep-alikes behind the jump... */
 472         while(is_Proj(last) || be_is_Keep(last)) {
 473                 last = sched_prev(last);
 474         }
 475
 476         if(!is_cfop(last)) {
 477                 last = sched_next(last);
 478                 /* last node must be a cfop, only exception is the start block */
 479                 assert(last     == get_irg_start_block(get_irn_irg(block)));
 480         }
 481
 482         return last;
 483 }
 484
 485 /**
 486  * We must adapt the live-outs to the live-ins at each block-border.
 487  */
 488 static
 489 void fix_block_borders(ir_node *block, void *data) {
 490         minibelady_env_t *env = data;
 491         ir_graph *irg = get_irn_irg(block);
 492         ir_node *startblock = get_irg_start_block(irg);
 493         int i;
 494         int arity;
 495         block_info_t *block_info;
 496
 497         if(block == startblock)
 498                 return;
 499
 500         DBG((dbg, LEVEL_3, "\n"));
 501
 502         block_info = get_block_info(block);
 503
 504         DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
 505              block_info->start_state));
 506
 507         /* process all pred blocks */
 508         arity = get_irn_arity(block);
 509         for (i = 0; i < arity; ++i) {
 510                 ir_node      *pred       = get_Block_cfgpred_block(block, i);
 511                 block_info_t *pred_info  = get_block_info(pred);
 512                 ir_node      *need_state = block_info->start_state;
 513
 514                 if(need_state == NULL)
 515                         continue;
 516
 517                 if(is_Phi(need_state) && get_nodes_block(need_state) == block) {
 518                         need_state = get_irn_n(need_state, i);
 519                 }
 520
 521                 DBG((dbg, LEVEL_3, "  Pred %+F (ends in %+F, we need %+F)\n", pred,
 522                      pred_info->end_state, need_state));
 523
 524                 if(pred_info->end_state != need_state) {
 525                         ir_node *insert_point = get_end_of_block_insertion_point(pred);
 526
 527
 528                         DBG((dbg, LEVEL_3, "  Creating reload for %+F\n", need_state));
 529                         create_reload(env, need_state, insert_point, pred_info->end_state);
 530                 }
 531         }
 532 }
 533
 534 void be_assure_state(be_irg_t *birg, const arch_register_t *reg, void *func_env,
 535                      create_spill_func create_spill,
 536                      create_reload_func create_reload) {
 537         minibelady_env_t env;
 538         ir_graph *irg = be_get_birg_irg(birg);
 539         spill_info_t *info;
 540         be_lv_t *lv = be_assure_liveness(birg);
 541
 542         be_liveness_assure_sets(lv);
 543         /* construct control flow loop tree */
 544         if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
 545                 construct_cf_backedges(irg);
 546         }
 547
 548         obstack_init(&env.obst);
 549         env.reg           = reg;
 550         env.func_env      = func_env;
 551         env.create_spill  = create_spill;
 552         env.create_reload = create_reload;
 553         env.lv            = be_get_birg_liveness(birg);
 554         env.uses          = be_begin_uses(irg, env.lv);
 555         env.spills        = NULL;
 556         ir_nodemap_init(&env.spill_infos);
 557
 558         assure_doms(irg);
 559         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 560         inc_irg_visited(irg);
 561
 562         /* process blocks */
 563         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 564
 565         /* fix block end_states that don't match the next blocks start_state */
 566         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 567
 568         ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 569
 570         /* reconstruct ssa-form */
 571         info = env.spills;
 572         while(info != NULL) {
 573                 be_ssa_construction_env_t senv;
 574                 int i, len;
 575                 ir_node **phis;
 576
 577                 be_ssa_construction_init(&senv, birg);
 578                 if(sched_is_scheduled(info->value))
 579                         be_ssa_construction_add_copy(&senv, info->value);
 580                 be_ssa_construction_add_copies(&senv,
 581                                                info->reloads, ARR_LEN(info->reloads));
 582                 be_ssa_construction_fix_users(&senv, info->value);
 583
 584                 if(lv != NULL) {
 585                         be_ssa_construction_update_liveness_phis(&senv, lv);
 586
 587                         be_liveness_update(lv, info->value);
 588                         len = ARR_LEN(info->reloads);
 589                         for(i = 0; i < len; ++i) {
 590                                 ir_node *reload = info->reloads[i];
 591                                 be_liveness_update(lv, reload);
 592                         }
 593                 }
 594
 595                 phis = be_ssa_construction_get_new_phis(&senv);
 596
 597                 /* set register requirements for phis */
 598                 len = ARR_LEN(phis);
 599                 for(i = 0; i < len; ++i) {
 600                         ir_node *phi = phis[i];
 601                         be_set_phi_flags(phi, arch_irn_flags_ignore);
 602                         arch_set_irn_register(phi, env.reg);
 603                 }
 604                 be_ssa_construction_destroy(&senv);
 605
 606                 info = info->next;
 607         }
 608
 609         /* some nodes might be dead now. */
 610         be_remove_dead_nodes_from_schedule(birg);
 611
 612         ir_nodemap_destroy(&env.spill_infos);
 613         be_end_uses(env.uses);
 614         obstack_free(&env.obst, NULL);
 615 }
 616
 617 void be_init_state(void)
 618 {
 619         FIRM_DBG_REGISTER(dbg, "firm.be.state");
 620 }
 621
 622 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);