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 #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_env_t      *arch_env;
  66         const arch_register_t *reg;
  67         const be_lv_t         *lv;
  68         void                  *func_env;
  69         create_reload_func     create_reload;
  70         create_spill_func      create_spill;
  71         spill_info_t          *spills;
  72         ir_nodemap_t           spill_infos;
  73
  74         be_uses_t             *uses;           /**< env for the next-use magic */
  75 } minibelady_env_t;
  76
  77 typedef struct block_info_t {
  78         ir_node *start_state;
  79         ir_node *end_state;
  80 } block_info_t;
  81
  82 static INLINE
  83 block_info_t *new_block_info(struct obstack *obst, ir_node *block)
  84 {
  85         block_info_t *res = obstack_alloc(obst, sizeof(*res));
  86         memset(res, 0, sizeof(res[0]));
  87
  88         assert(is_Block(block));
  89         set_irn_link(block, res);
  90         mark_irn_visited(block);
  91
  92         return res;
  93 }
  94
  95 static INLINE
  96 block_info_t *get_block_info(ir_node *block)
  97 {
  98         assert(irn_visited(block));
  99         return (block_info_t*) get_irn_link(block);
 100 }
 101
 102 static INLINE
 103 spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
 104 {
 105         spill_info_t *spill_info = obstack_alloc(&env->obst, sizeof(spill_info[0]));
 106         memset(spill_info, 0, sizeof(spill_info[0]));
 107         spill_info->value = state;
 108         spill_info->reloads = NEW_ARR_F(ir_node*, 0);
 109
 110         ir_nodemap_insert(&env->spill_infos, state, spill_info);
 111         //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
 112
 113         spill_info->next = env->spills;
 114         env->spills = spill_info;
 115
 116         return spill_info;
 117 }
 118
 119 static INLINE
 120 spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
 121 {
 122         spill_info_t *spill_info
 123                 = (spill_info_t*) ir_nodemap_get(&env->spill_infos, node);
 124         //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
 125         return spill_info;
 126 }
 127
 128 static
 129 spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
 130 {
 131         spill_info_t *spill_info;
 132         ir_node *next;
 133         ir_node *after;
 134
 135         spill_info = get_spill_info(env, state);
 136         if(spill_info == NULL) {
 137                 spill_info = create_spill_info(env, state);
 138         } else if(spill_info->spill != NULL) {
 139                 return spill_info;
 140         }
 141
 142         if(sched_is_scheduled(state)) {
 143                 next = state;
 144                 do {
 145                         after = next;
 146                         next = sched_next(after);
 147                 } while(is_Proj(next) || is_Phi(next) || be_is_Keep(next));
 148         } else {
 149                 after = state;
 150         }
 151         spill_info->spill = env->create_spill(env->func_env, state, force, after);
 152
 153         return spill_info;
 154 }
 155
 156 static
 157 void create_reload(minibelady_env_t *env, ir_node *state, ir_node *before,
 158                    ir_node *last_state)
 159 {
 160         spill_info_t *spill_info = create_spill(env, state, 0);
 161         ir_node *spill = spill_info->spill;
 162         ir_node *reload;
 163
 164         reload = env->create_reload(env->func_env, state, spill, before,
 165                                     last_state);
 166         ARR_APP1(ir_node*, spill_info->reloads, reload);
 167 }
 168
 169 static
 170 void spill_phi(minibelady_env_t *env, ir_node *phi)
 171 {
 172         ir_graph *irg = get_irn_irg(phi);
 173         ir_node *block = get_nodes_block(phi);
 174         int i, arity = get_irn_arity(phi);
 175         ir_node **in = alloca(arity * sizeof(in[0]));
 176         ir_node *spill_to_kill = NULL;
 177         spill_info_t *spill_info;
 178
 179         /* does a spill exist for the phis value? */
 180         spill_info = get_spill_info(env, phi);
 181         if(spill_info != NULL) {
 182                 spill_to_kill = spill_info->spill;
 183         } else {
 184                 spill_info = create_spill_info(env, phi);
 185         }
 186
 187         /* create a new phi-M with bad preds */
 188         for(i = 0; i < arity; ++i) {
 189                 in[i] = new_r_Unknown(irg, mode_M);
 190         }
 191
 192         DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
 193
 194         /* create a Phi-M */
 195         spill_info->spill = new_r_Phi(irg, block, arity, in, mode_M);
 196
 197         if(spill_to_kill != NULL) {
 198                 exchange(spill_to_kill, spill_info->spill);
 199                 sched_remove(spill_to_kill);
 200         }
 201
 202         /* create spills for the phi values */
 203         for(i = 0; i < arity; ++i) {
 204                 ir_node *in = get_irn_n(phi, i);
 205                 spill_info_t *pred_spill = create_spill(env, in, 1);
 206                 set_irn_n(spill_info->spill, i, pred_spill->spill);
 207         }
 208 }
 209
 210 static
 211 void belady(minibelady_env_t *env, ir_node *block);
 212
 213 /**
 214  * Collects all values live-in at block @p block and all phi results in this
 215  * block.
 216  * Then it adds the best values (at most n_regs) to the blocks start_workset.
 217  * The phis among the remaining values get spilled: Introduce psudo-copies of
 218  * their args to break interference and make it possible to spill them to the
 219  * same spill slot.
 220  */
 221 static
 222 block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
 223 {
 224         block_info_t  *block_info;
 225         be_next_use_t  next_use;
 226         ir_loop       *loop;
 227         ir_node       *best_starter, *first;
 228         ir_node       *node;
 229         int            n_cfgpreds;
 230         unsigned       best_time;
 231         int            outer_loop_allowed;
 232         int            i;
 233
 234         /* Create the block info for this block. */
 235         block_info = new_block_info(&env->obst, block);
 236         n_cfgpreds = get_Block_n_cfgpreds(block);
 237
 238         /* no cfgpred -> no value active */
 239         if(n_cfgpreds == 0) {
 240                 block_info->start_state = NULL;
 241                 return block_info;
 242         }
 243
 244         /* for 1 pred only: simply take the the end-state of the pred */
 245         if(n_cfgpreds == 1) {
 246                 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
 247                 block_info_t *pred_info;
 248
 249                 /* process pred block */
 250                 belady(env, pred_block);
 251
 252                 pred_info = get_block_info(pred_block);
 253
 254                 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
 255                 block_info->start_state = pred_info->end_state;
 256                 return block_info;
 257         }
 258
 259         /* Collect all values living at start of block */
 260         DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
 261         first = sched_first(block);
 262         loop = get_irn_loop(block);
 263         best_starter = NULL;
 264         best_time = USES_INFINITY;
 265         outer_loop_allowed = 1;
 266
 267         /* check all Phis first */
 268         sched_foreach(block, node) {
 269                 if (!is_Phi(node))
 270                         break;
 271                 if (arch_get_irn_register(env->arch_env, node) != env->reg)
 272                         continue;
 273
 274                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 275                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 276
 277                 if(USES_IS_INFINITE(next_use.time)) {
 278                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 279                         continue;
 280                 }
 281
 282                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 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
 287                                 if(best_starter != NULL) {
 288                                         /* spill the phi as it is not used */
 289                                         spill_phi(env, best_starter);
 290                                 }
 291                                 best_starter = node;
 292                                 best_time = next_use.time;
 293                                 outer_loop_allowed = 0;
 294                         }
 295                 } else {
 296                         if(outer_loop_allowed && next_use.time < best_time) {
 297                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 298                                      next_use.outermost_loop));
 299                                 if(best_starter != NULL) {
 300                                         /* spill the phi as it is not used */
 301                                         spill_phi(env, best_starter);
 302                                 }
 303                                 best_starter = node;
 304                                 best_time = next_use.time;
 305                         }
 306                 }
 307
 308                 if(best_starter != node) {
 309                         /* spill the phi as it is not used */
 310                         spill_phi(env, best_starter);
 311                 }
 312         }
 313
 314         /* check all Live-Ins */
 315         be_lv_foreach(env->lv, block, be_lv_state_in, i) {
 316                 node = be_lv_get_irn(env->lv, block, i);
 317
 318                 if(!mode_is_data(get_irn_mode(node)))
 319                         continue;
 320
 321                 if (arch_get_irn_register(env->arch_env, node) != env->reg)
 322                         continue;
 323
 324                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 325                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 326
 327                 if(USES_IS_INFINITE(next_use.time)) {
 328                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 329                         continue;
 330                 }
 331
 332                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 333                         if(outer_loop_allowed || next_use.time < best_time) {
 334                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 335                                      next_use.outermost_loop));
 336
 337                                 if(best_starter != NULL && is_Phi(best_starter)) {
 338                                         /* spill the phi as it is not used */
 339                                         spill_phi(env, best_starter);
 340                                 }
 341                                 best_starter = node;
 342                                 best_time = next_use.time;
 343                                 outer_loop_allowed = 0;
 344                         }
 345                 } else {
 346                         if(outer_loop_allowed && next_use.time < best_time) {
 347                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 348                                      next_use.outermost_loop));
 349                                 if(best_starter != NULL && is_Phi(best_starter)) {
 350                                         /* spill the phi as it is not used */
 351                                         spill_phi(env, best_starter);
 352                                 }
 353                                 best_starter = node;
 354                                 best_time = next_use.time;
 355                         }
 356                 }
 357         }
 358
 359         block_info->start_state = best_starter;
 360
 361         return block_info;
 362 }
 363
 364 /**
 365  * For the given block @p block, decide for each values
 366  * whether it is used from a register or is reloaded
 367  * before the use.
 368  */
 369 static
 370 void belady(minibelady_env_t *env, ir_node *block)
 371 {
 372         ir_node *current_state;
 373         ir_node *node;
 374         block_info_t *block_info;
 375
 376         /* Don't do a block twice */
 377         if(irn_visited(block))
 378                 return;
 379
 380         /* compute value to start with */
 381         block_info = compute_block_start_state(env, block);
 382
 383         /* get the starting workset for this block */
 384         DBG((dbg, LEVEL_3, "\n"));
 385         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 386
 387         current_state = block_info->start_state;
 388         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 389
 390         /* process the block from start to end */
 391         DBG((dbg, LEVEL_3, "Processing...\n"));
 392
 393         sched_foreach(block, node) {
 394                 int i, arity;
 395                 ir_node *need_val = NULL;
 396
 397                 /* projs are handled with the tuple value.
 398                  * Phis are no real instr (see insert_starters()) */
 399                 if (is_Proj(node) || is_Phi(node)) {
 400                         continue;
 401                 }
 402
 403                 /* check which state is desired for the node */
 404                 arity = get_irn_arity(node);
 405                 for(i = 0; i < arity; ++i) {
 406                         const arch_register_t *reg;
 407                         ir_node *in = get_irn_n(node, i);
 408
 409                         if(!mode_is_data(get_irn_mode(in)))
 410                                 continue;
 411
 412                         reg = arch_get_irn_register(env->arch_env, in);
 413                         if(reg == env->reg) {
 414                                 assert(need_val == NULL);
 415                                 need_val = in;
 416                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 417                         }
 418                 }
 419                 /* create a reload to match state if necessary */
 420                 if(need_val != NULL && need_val != current_state) {
 421                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 422                         create_reload(env, need_val, node, current_state);
 423                         current_state = need_val;
 424                 }
 425
 426                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 427
 428                 /* record state changes by the node */
 429                 if (get_irn_mode(node) == mode_T) {
 430                         const ir_edge_t *edge;
 431
 432                         foreach_out_edge(node, edge) {
 433                                 const arch_register_t *reg;
 434                                 ir_node *proj = get_edge_src_irn(edge);
 435
 436                                 if(!mode_is_data(get_irn_mode(proj)))
 437                                         continue;
 438
 439                                 reg = arch_get_irn_register(env->arch_env, proj);
 440                                 if(reg == env->reg) {
 441                                         current_state = proj;
 442                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 443                                 }
 444                         }
 445                 } else {
 446                         if(mode_is_data(get_irn_mode(node))) {
 447                                 const arch_register_t *reg =
 448                                         arch_get_irn_register(env->arch_env, node);
 449                                 if(reg == env->reg) {
 450                                         current_state = node;
 451                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 452                                 }
 453                         }
 454                 }
 455         }
 456
 457         /* Remember end-workset for this block */
 458         block_info->end_state = current_state;
 459         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 460 }
 461
 462 static
 463 void belady_walker(ir_node *block, void *data)
 464 {
 465         belady((minibelady_env_t*) data, block);
 466 }
 467
 468 static
 469 ir_node *get_end_of_block_insertion_point(ir_node *block)
 470 {
 471         ir_node *last = sched_last(block);
 472
 473         /* skip Projs and Keep-alikes behind the jump... */
 474         while(is_Proj(last) || be_is_Keep(last)) {
 475                 last = sched_prev(last);
 476         }
 477
 478         if(!is_cfop(last)) {
 479                 last = sched_next(last);
 480                 /* last node must be a cfop, only exception is the start block */
 481                 assert(last     == get_irg_start_block(get_irn_irg(block)));
 482         }
 483
 484         return last;
 485 }
 486
 487 /**
 488  * We must adapt the live-outs to the live-ins at each block-border.
 489  */
 490 static
 491 void fix_block_borders(ir_node *block, void *data) {
 492         minibelady_env_t *env = data;
 493         ir_graph *irg = get_irn_irg(block);
 494         ir_node *startblock = get_irg_start_block(irg);
 495         int i;
 496         int arity;
 497         block_info_t *block_info;
 498
 499         if(block == startblock)
 500                 return;
 501
 502         DBG((dbg, LEVEL_3, "\n"));
 503
 504         block_info = get_block_info(block);
 505
 506         DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
 507              block_info->start_state));
 508
 509         /* process all pred blocks */
 510         arity = get_irn_arity(block);
 511         for (i = 0; i < arity; ++i) {
 512                 ir_node      *pred       = get_Block_cfgpred_block(block, i);
 513                 block_info_t *pred_info  = get_block_info(pred);
 514                 ir_node      *need_state = block_info->start_state;
 515
 516                 if(need_state == NULL)
 517                         continue;
 518
 519                 if(is_Phi(need_state) && get_nodes_block(need_state) == block) {
 520                         need_state = get_irn_n(need_state, i);
 521                 }
 522
 523                 DBG((dbg, LEVEL_3, "  Pred %+F (ends in %+F, we need %+F)\n", pred,
 524                      pred_info->end_state, need_state));
 525
 526                 if(pred_info->end_state != need_state) {
 527                         ir_node *insert_point = get_end_of_block_insertion_point(pred);
 528
 529
 530                         DBG((dbg, LEVEL_3, "  Creating reload for %+F\n", need_state));
 531                         create_reload(env, need_state, insert_point, pred_info->end_state);
 532                 }
 533         }
 534 }
 535
 536 void be_assure_state(be_irg_t *birg, const arch_register_t *reg, void *func_env,
 537                      create_spill_func create_spill,
 538                      create_reload_func create_reload) {
 539         minibelady_env_t env;
 540         ir_graph *irg = be_get_birg_irg(birg);
 541         spill_info_t *info;
 542         be_lv_t *lv = be_assure_liveness(birg);
 543
 544         be_liveness_assure_sets(lv);
 545         be_assure_dom_front(birg);
 546         /* construct control flow loop tree */
 547         if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
 548                 construct_cf_backedges(irg);
 549         }
 550
 551         obstack_init(&env.obst);
 552         env.arch_env      = be_get_birg_arch_env(birg);
 553         env.reg           = reg;
 554         env.func_env      = func_env;
 555         env.create_spill  = create_spill;
 556         env.create_reload = create_reload;
 557         env.lv            = be_get_birg_liveness(birg);
 558         env.uses          = be_begin_uses(irg, env.lv);
 559         env.spills        = NULL;
 560         ir_nodemap_init(&env.spill_infos);
 561
 562         assure_doms(irg);
 563         set_using_visited(irg);
 564         set_using_irn_link(irg);
 565         inc_irg_visited(irg);
 566
 567         /* process blocks */
 568         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 569
 570         /* fix block end_states that don't match the next blocks start_state */
 571         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 572
 573         clear_using_visited(irg);
 574         clear_using_irn_link(irg);
 575
 576         /* reconstruct ssa-form */
 577         info = env.spills;
 578         while(info != NULL) {
 579                 be_ssa_construction_env_t senv;
 580                 int i, len;
 581                 ir_node **phis;
 582
 583                 be_ssa_construction_init(&senv, birg);
 584                 if(sched_is_scheduled(info->value))
 585                         be_ssa_construction_add_copy(&senv, info->value);
 586                 be_ssa_construction_add_copies(&senv,
 587                                                info->reloads, ARR_LEN(info->reloads));
 588                 be_ssa_construction_fix_users(&senv, info->value);
 589
 590                 if(lv != NULL) {
 591                         be_ssa_construction_update_liveness_phis(&senv, lv);
 592
 593                         be_liveness_update(lv, info->value);
 594                         len = ARR_LEN(info->reloads);
 595                         for(i = 0; i < len; ++i) {
 596                                 ir_node *reload = info->reloads[i];
 597                                 be_liveness_update(lv, reload);
 598                         }
 599                 }
 600
 601                 phis = be_ssa_construction_get_new_phis(&senv);
 602
 603                 /* set register requirements for phis */
 604                 len = ARR_LEN(phis);
 605                 for(i = 0; i < len; ++i) {
 606                         ir_node *phi = phis[i];
 607                         be_set_phi_flags(env.arch_env, phi, arch_irn_flags_ignore);
 608                         arch_set_irn_register(env.arch_env, phi, env.reg);
 609                 }
 610                 be_ssa_construction_destroy(&senv);
 611
 612                 info = info->next;
 613         }
 614
 615         /* some nodes might be dead now. */
 616         be_remove_dead_nodes_from_schedule(birg);
 617
 618         ir_nodemap_destroy(&env.spill_infos);
 619         be_end_uses(env.uses);
 620         obstack_free(&env.obst, NULL);
 621 }
 622
 623 void be_init_state(void)
 624 {
 625         FIRM_DBG_REGISTER(dbg, "firm.be.state");
 626 }
 627
 628 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);