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  * Copyright:   (c) Universitaet Karlsruhe
  28  * Licence:     This file protected by GPL -  GNU GENERAL PUBLIC LICENSE.
  29  */
  30 #ifdef HAVE_CONFIG_H
  31 #include "config.h"
  32 #endif
  33
  34 #include "bestate.h"
  35
  36 #include "obst.h"
  37 #include "irgraph_t.h"
  38 #include "irnode_t.h"
  39 #include "irgwalk.h"
  40 #include "irloop.h"
  41 #include "iredges_t.h"
  42 #include "ircons_t.h"
  43 #include "irgmod.h"
  44
  45 #include "bearch_t.h"
  46 #include "beuses_t.h"
  47 #include "besched_t.h"
  48 #include "belive_t.h"
  49 #include "bemodule.h"
  50 #include "benode_t.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_env_t      *arch_env;
  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
  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
  81 block_info_t *new_block_info(struct obstack *obst, ir_node *block)
  82 {
  83         block_info_t *res = obstack_alloc(obst, sizeof(*res));
  84         memset(res, 0, sizeof(res[0]));
  85
  86         set_irn_link(block, res);
  87         mark_irn_visited(block);
  88
  89         return res;
  90 }
  91
  92 static INLINE
  93 block_info_t *get_block_info(ir_node *block)
  94 {
  95         assert(irn_visited(block));
  96         return (block_info_t*) get_irn_link(block);
  97 }
  98
  99 static INLINE
 100 spill_info_t *create_spill_info(minibelady_env_t *env, ir_node *state)
 101 {
 102         spill_info_t *spill_info = obstack_alloc(&env->obst, sizeof(spill_info[0]));
 103         memset(spill_info, 0, sizeof(spill_info[0]));
 104         spill_info->value = state;
 105         spill_info->reloads = NEW_ARR_F(ir_node*, 0);
 106
 107         set_irn_link(state, spill_info);
 108         mark_irn_visited(state);
 109
 110         spill_info->next = env->spills;
 111         env->spills = spill_info;
 112
 113         return spill_info;
 114 }
 115
 116 static
 117 spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
 118 {
 119         spill_info_t *spill_info;
 120         ir_node *next;
 121         ir_node *after;
 122
 123         if(irn_visited(state)) {
 124                 spill_info = (spill_info_t*) get_irn_link(state);
 125                 if(spill_info->spill != NULL || !force)
 126                         return spill_info;
 127         } else {
 128                 spill_info = create_spill_info(env, state);
 129         }
 130
 131         if(sched_is_scheduled(state)) {
 132                 next = state;
 133                 do {
 134                         after = next;
 135                         next = sched_next(after);
 136                 } while(is_Proj(next) || is_Phi(next) || be_is_Keep(next));
 137         } else {
 138                 after = state;
 139         }
 140         spill_info->spill = env->create_spill(env->func_env, state, force, after);
 141
 142         return spill_info;
 143 }
 144
 145 static
 146 void create_reload(minibelady_env_t *env, ir_node *state, ir_node *before,
 147                    ir_node *last_state)
 148 {
 149         spill_info_t *spill_info = create_spill(env, state, 0);
 150         ir_node *spill = spill_info->spill;
 151         ir_node *reload;
 152
 153         reload = env->create_reload(env->func_env, state, spill, before,
 154                                     last_state);
 155         ARR_APP1(ir_node*, spill_info->reloads, reload);
 156 }
 157
 158 static
 159 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 i, arity = get_irn_arity(phi);
 164         ir_node **in = alloca(arity * sizeof(in[0]));
 165         ir_node *spill_to_kill = NULL;
 166         spill_info_t *spill_info;
 167
 168         /* does a spill exist for the phis value? */
 169         if(irn_visited(phi)) {
 170                 spill_info = (spill_info_t*) get_irn_link(phi);
 171                 spill_to_kill = spill_info->spill;
 172         } else {
 173                 spill_info = create_spill_info(env, phi);
 174         }
 175
 176         /* create a new phi-M with bad preds */
 177         for(i = 0; i < arity; ++i) {
 178                 in[i] = new_r_Bad(irg);
 179         }
 180
 181         DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
 182
 183         /* create a Phi-M */
 184         spill_info->spill = new_r_Phi(irg, block, arity, in, mode_M);
 185
 186         if(spill_to_kill != NULL) {
 187                 exchange(spill_to_kill, spill_info->spill);
 188                 sched_remove(spill_to_kill);
 189         }
 190
 191         /* create spills for the phi values */
 192         for(i = 0; i < arity; ++i) {
 193                 ir_node *in = get_irn_n(phi, i);
 194                 spill_info_t *pred_spill = create_spill(env, in, 1);
 195                 set_irn_n(spill_info->spill, i, pred_spill->spill);
 196         }
 197 }
 198
 199 static
 200 void belady(minibelady_env_t *env, ir_node *block);
 201
 202 /**
 203  * Collects all values live-in at block @p block and all phi results in this
 204  * block.
 205  * Then it adds the best values (at most n_regs) to the blocks start_workset.
 206  * The phis among the remaining values get spilled: Introduce psudo-copies of
 207  * their args to break interference and make it possible to spill them to the
 208  * same spill slot.
 209  */
 210 static
 211 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(env->arch_env, 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, 0, 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 (arch_get_irn_register(env->arch_env, node) != env->reg)
 308                         continue;
 309
 310                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 311                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 312
 313                 if(USES_IS_INFINITE(next_use.time)) {
 314                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 315                         continue;
 316                 }
 317
 318                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 319                         if(outer_loop_allowed || next_use.time < best_time) {
 320                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 321                                      next_use.outermost_loop));
 322
 323                                 if(best_starter != NULL && is_Phi(best_starter)) {
 324                                         /* spill the phi as it is not used */
 325                                         spill_phi(env, best_starter);
 326                                 }
 327                                 best_starter = node;
 328                                 best_time = next_use.time;
 329                                 outer_loop_allowed = 0;
 330                         }
 331                 } else {
 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                                 if(best_starter != NULL && is_Phi(best_starter)) {
 336                                         /* spill the phi as it is not used */
 337                                         spill_phi(env, best_starter);
 338                                 }
 339                                 best_starter = node;
 340                                 best_time = next_use.time;
 341                         }
 342                 }
 343         }
 344
 345         block_info->start_state = best_starter;
 346
 347         return block_info;
 348 }
 349
 350 /**
 351  * For the given block @p block, decide for each values
 352  * whether it is used from a register or is reloaded
 353  * before the use.
 354  */
 355 static
 356 void belady(minibelady_env_t *env, ir_node *block)
 357 {
 358         ir_node *current_state;
 359         ir_node *node;
 360         block_info_t *block_info;
 361
 362         /* Don't do a block twice */
 363         if(irn_visited(block))
 364                 return;
 365
 366         /* compute value to start with */
 367         block_info = compute_block_start_state(env, block);
 368
 369         /* get the starting workset for this block */
 370         DBG((dbg, LEVEL_3, "\n"));
 371         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 372
 373         current_state = block_info->start_state;
 374         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 375
 376         /* process the block from start to end */
 377         DBG((dbg, LEVEL_3, "Processing...\n"));
 378
 379         sched_foreach(block, node) {
 380                 int i, arity;
 381                 ir_node *need_val = NULL;
 382
 383                 /* projs are handled with the tuple value.
 384                  * Phis are no real instr (see insert_starters()) */
 385                 if (is_Proj(node) || is_Phi(node)) {
 386                         continue;
 387                 }
 388
 389                 /* check which state is desired for the node */
 390                 arity = get_irn_arity(node);
 391                 for(i = 0; i < arity; ++i) {
 392                         ir_node *in = get_irn_n(node, i);
 393                         const arch_register_t *reg =
 394                                 arch_get_irn_register(env->arch_env, in);
 395                         if(reg == env->reg) {
 396                                 assert(need_val == NULL);
 397                                 need_val = in;
 398                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 399                         }
 400                 }
 401                 /* create a reload to match state if necessary */
 402                 if(need_val != NULL && need_val != current_state) {
 403                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 404                         create_reload(env, need_val, node, current_state);
 405                         current_state = need_val;
 406                 }
 407
 408                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 409
 410                 /* record state changes by the node */
 411                 if (get_irn_mode(node) == mode_T) {
 412                         ir_node *proj;
 413                         for(proj = sched_next(node); is_Proj(proj);
 414                             proj = sched_next(proj)) {
 415                                 const arch_register_t *reg =
 416                                         arch_get_irn_register(env->arch_env, proj);
 417                                 if(reg == env->reg) {
 418                                         current_state = proj;
 419                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 420                                 }
 421                         }
 422                 } else {
 423                         const arch_register_t *reg =
 424                                 arch_get_irn_register(env->arch_env, node);
 425                         if(reg == env->reg) {
 426                                 current_state = node;
 427                                 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 428                         }
 429                 }
 430         }
 431
 432         /* Remember end-workset for this block */
 433         block_info->end_state = current_state;
 434         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 435 }
 436
 437 static
 438 void belady_walker(ir_node *block, void *data)
 439 {
 440         belady((minibelady_env_t*) data, block);
 441 }
 442
 443 static
 444 ir_node *get_end_of_block_insertion_point(ir_node *block)
 445 {
 446         ir_node *last = sched_last(block);
 447
 448         /* skip projs and keepanies behind the jump... */
 449         while(is_Proj(last) || be_is_Keep(last)) {
 450                 last = sched_prev(last);
 451         }
 452
 453         if(!is_cfop(last)) {
 454                 last = sched_next(last);
 455                 // last node must be a cfop, only exception is the start block
 456                 assert(last     == get_irg_start_block(get_irn_irg(block)));
 457         }
 458
 459         return last;
 460 }
 461
 462 /**
 463  * We must adapt the live-outs to the live-ins at each block-border.
 464  */
 465 static
 466 void fix_block_borders(ir_node *block, void *data) {
 467         minibelady_env_t *env = data;
 468         ir_graph *irg = get_irn_irg(block);
 469         ir_node *startblock = get_irg_start_block(irg);
 470         int i;
 471         int arity;
 472         block_info_t *block_info;
 473
 474         if(block == startblock)
 475                 return;
 476
 477         DBG((dbg, LEVEL_3, "\n"));
 478         DBG((dbg, LEVEL_3, "Fixing %+F\n", block));
 479
 480         block_info = get_block_info(block);
 481
 482         /* process all pred blocks */
 483         arity = get_irn_arity(block);
 484         for (i = 0; i < arity; ++i) {
 485                 ir_node *pred = get_Block_cfgpred_block(block, i);
 486                 block_info_t *pred_info = get_block_info(pred);
 487
 488                 DBG((dbg, LEVEL_3, "  Pred %+F\n", pred));
 489
 490                 if(pred_info->end_state != block_info->start_state &&
 491                         block_info->start_state != NULL) {
 492                         ir_node *need_state = block_info->start_state;
 493                         ir_node *insert_point =
 494                                 get_end_of_block_insertion_point(pred);
 495
 496                         create_reload(env, need_state, insert_point, pred_info->end_state);
 497                 }
 498         }
 499 }
 500
 501 void be_assure_state(be_irg_t *birg, const arch_register_t *reg, void *func_env,
 502                      create_spill_func create_spill,
 503                      create_reload_func create_reload) {
 504         minibelady_env_t env;
 505         ir_graph *irg = be_get_birg_irg(birg);
 506         spill_info_t *info;
 507         be_lv_t *lv = be_get_birg_liveness(birg);
 508
 509         be_assure_liveness(birg);
 510         be_assure_dom_front(birg);
 511         /* construct control flow loop tree */
 512         if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
 513                 construct_cf_backedges(irg);
 514         }
 515
 516         obstack_init(&env.obst);
 517         env.arch_env      = be_get_birg_arch_env(birg);
 518         env.reg           = reg;
 519         env.func_env      = func_env;
 520         env.create_spill  = create_spill;
 521         env.create_reload = create_reload;
 522         env.lv            = be_get_birg_liveness(birg);
 523         env.uses          = be_begin_uses(irg, env.lv);
 524         env.spills        = NULL;
 525
 526         set_using_visited(irg);
 527         set_using_irn_link(irg);
 528         inc_irg_visited(irg);
 529
 530         /* process blocks */
 531         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 532
 533         /* fix block end_states that don't match the next blocks start_state */
 534         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 535
 536         clear_using_visited(irg);
 537         clear_using_irn_link(irg);
 538
 539         /* reconstruct ssa-form */
 540         info = env.spills;
 541         while(info != NULL) {
 542                 be_ssa_construction_env_t senv;
 543                 int i, len;
 544                 ir_node **phis;
 545
 546                 be_ssa_construction_init(&senv, birg);
 547                 if(sched_is_scheduled(info->value))
 548                         be_ssa_construction_add_copy(&senv, info->value);
 549                 be_ssa_construction_add_copies(&senv,
 550                                                info->reloads, ARR_LEN(info->reloads));
 551                 be_ssa_construction_fix_users(&senv, info->value);
 552
 553                 if(lv != NULL) {
 554                         be_ssa_construction_update_liveness_phis(&senv, lv);
 555
 556                         be_liveness_update(lv, info->value);
 557                         len = ARR_LEN(info->reloads);
 558                         for(i = 0; i < len; ++i) {
 559                                 ir_node *reload = info->reloads[i];
 560                                 be_liveness_update(lv, reload);
 561                         }
 562                 }
 563
 564                 phis = be_ssa_construction_get_new_phis(&senv);
 565
 566                 /* set register requirements for phis */
 567                 len = ARR_LEN(phis);
 568                 for(i = 0; i < len; ++i) {
 569                         ir_node *phi = phis[i];
 570                         be_set_phi_flags(env.arch_env, phi, arch_irn_flags_ignore);
 571                         arch_set_irn_register(env.arch_env, phi, env.reg);
 572                 }
 573                 be_ssa_construction_destroy(&senv);
 574
 575                 info = info->next;
 576         }
 577
 578         /* some nodes might be dead now. */
 579         be_remove_dead_nodes_from_schedule(irg);
 580
 581         be_end_uses(env.uses);
 582         obstack_free(&env.obst, NULL);
 583 }
 584
 585 void be_init_state(void)
 586 {
 587         FIRM_DBG_REGISTER(dbg, "firm.be.state");
 588 }
 589
 590 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);