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 #include "config.h"
  29
  30 #include "bestate.h"
  31
  32 #include "obst.h"
  33 #include "irgraph_t.h"
  34 #include "irnode_t.h"
  35 #include "irgwalk.h"
  36 #include "irloop.h"
  37 #include "iredges_t.h"
  38 #include "ircons_t.h"
  39 #include "irgmod.h"
  40 #include "irnodeset.h"
  41 #include "irnodemap.h"
  42 #include "adt/cpset.h"
  43
  44 #include "bearch_t.h"
  45 #include "beuses.h"
  46 #include "besched_t.h"
  47 #include "belive_t.h"
  48 #include "bemodule.h"
  49 #include "benode_t.h"
  50 #include "bessaconstr.h"
  51
  52 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  53
  54 typedef struct spill_info_t {
  55         struct spill_info_t *next;
  56         ir_node *value;
  57         ir_node *spill;
  58         ir_node **reloads;
  59 } spill_info_t;
  60
  61 typedef struct minibelady_env_t {
  62         struct obstack         obst;
  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         ir_nodemap_t           spill_infos;
  70
  71         be_uses_t             *uses;           /**< env for the next-use magic */
  72 } minibelady_env_t;
  73
  74 typedef struct block_info_t {
  75         ir_node *start_state;
  76         ir_node *end_state;
  77 } block_info_t;
  78
  79 static inline
  80 block_info_t *new_block_info(struct obstack *obst, ir_node *block)
  81 {
  82         block_info_t *res = obstack_alloc(obst, sizeof(*res));
  83         memset(res, 0, sizeof(res[0]));
  84
  85         assert(is_Block(block));
  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         ir_nodemap_insert(&env->spill_infos, state, spill_info);
 108         //ir_fprintf(stderr, "Insert %+F -> %p\n", state, spill_info);
 109
 110         spill_info->next = env->spills;
 111         env->spills = spill_info;
 112
 113         return spill_info;
 114 }
 115
 116 static inline
 117 spill_info_t *get_spill_info(minibelady_env_t *env, const ir_node *node)
 118 {
 119         spill_info_t *spill_info
 120                 = (spill_info_t*) ir_nodemap_get(&env->spill_infos, node);
 121         //ir_fprintf(stderr, "Get %+F -> %p\n", node, spill_info);
 122         return spill_info;
 123 }
 124
 125 static
 126 spill_info_t *create_spill(minibelady_env_t *env, ir_node *state, int force)
 127 {
 128         spill_info_t *spill_info;
 129         ir_node *next;
 130         ir_node *after;
 131
 132         spill_info = get_spill_info(env, state);
 133         if(spill_info == NULL) {
 134                 spill_info = create_spill_info(env, state);
 135         } else if(spill_info->spill != NULL) {
 136                 return spill_info;
 137         }
 138
 139         if(sched_is_scheduled(state)) {
 140                 next = state;
 141                 do {
 142                         after = next;
 143                         next = sched_next(after);
 144                 } while(is_Proj(next) || is_Phi(next) || be_is_Keep(next));
 145         } else {
 146                 after = state;
 147         }
 148         spill_info->spill = env->create_spill(env->func_env, state, force, after);
 149
 150         return spill_info;
 151 }
 152
 153 static
 154 void create_reload(minibelady_env_t *env, ir_node *state, ir_node *before,
 155                    ir_node *last_state)
 156 {
 157         spill_info_t *spill_info = create_spill(env, state, 0);
 158         ir_node *spill = spill_info->spill;
 159         ir_node *reload;
 160
 161         reload = env->create_reload(env->func_env, state, spill, before,
 162                                     last_state);
 163         ARR_APP1(ir_node*, spill_info->reloads, reload);
 164 }
 165
 166 static
 167 void spill_phi(minibelady_env_t *env, ir_node *phi)
 168 {
 169         ir_graph     *irg           = get_irn_irg(phi);
 170         ir_node      *block         = get_nodes_block(phi);
 171         int           arity         = get_irn_arity(phi);
 172         ir_node     **in            = ALLOCAN(ir_node*, arity);
 173         ir_node      *spill_to_kill = NULL;
 174         spill_info_t *spill_info;
 175         int           i;
 176
 177         /* does a spill exist for the phis value? */
 178         spill_info = get_spill_info(env, phi);
 179         if(spill_info != NULL) {
 180                 spill_to_kill = spill_info->spill;
 181         } else {
 182                 spill_info = create_spill_info(env, phi);
 183         }
 184
 185         /* create a new phi-M with bad preds */
 186         for(i = 0; i < arity; ++i) {
 187                 in[i] = new_r_Unknown(irg, mode_M);
 188         }
 189
 190         DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
 191
 192         /* create a Phi-M */
 193         spill_info->spill = new_r_Phi(block, arity, in, mode_M);
 194
 195         if(spill_to_kill != NULL) {
 196                 exchange(spill_to_kill, spill_info->spill);
 197                 sched_remove(spill_to_kill);
 198         }
 199
 200         /* create spills for the phi values */
 201         for(i = 0; i < arity; ++i) {
 202                 ir_node *in = get_irn_n(phi, i);
 203                 spill_info_t *pred_spill = create_spill(env, in, 1);
 204                 set_irn_n(spill_info->spill, i, pred_spill->spill);
 205         }
 206 }
 207
 208 static
 209 void belady(minibelady_env_t *env, ir_node *block);
 210
 211 /**
 212  * Collects all values live-in at block @p block and all phi results in this
 213  * block.
 214  * Then it adds the best values (at most n_regs) to the blocks start_workset.
 215  * The phis among the remaining values get spilled: Introduce psudo-copies of
 216  * their args to break interference and make it possible to spill them to the
 217  * same spill slot.
 218  */
 219 static
 220 block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
 221 {
 222         block_info_t  *block_info;
 223         be_next_use_t  next_use;
 224         ir_loop       *loop;
 225         ir_node       *best_starter, *first;
 226         ir_node       *node;
 227         int            n_cfgpreds;
 228         unsigned       best_time;
 229         int            outer_loop_allowed;
 230         int            i;
 231
 232         /* Create the block info for this block. */
 233         block_info = new_block_info(&env->obst, block);
 234         n_cfgpreds = get_Block_n_cfgpreds(block);
 235
 236         /* no cfgpred -> no value active */
 237         if(n_cfgpreds == 0) {
 238                 block_info->start_state = NULL;
 239                 return block_info;
 240         }
 241
 242         /* for 1 pred only: simply take the the end-state of the pred */
 243         if(n_cfgpreds == 1) {
 244                 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
 245                 block_info_t *pred_info;
 246
 247                 /* process pred block */
 248                 belady(env, pred_block);
 249
 250                 pred_info = get_block_info(pred_block);
 251
 252                 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
 253                 block_info->start_state = pred_info->end_state;
 254                 return block_info;
 255         }
 256
 257         /* Collect all values living at start of block */
 258         DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
 259         first = sched_first(block);
 260         loop = get_irn_loop(block);
 261         best_starter = NULL;
 262         best_time = USES_INFINITY;
 263         outer_loop_allowed = 1;
 264
 265         /* check all Phis first */
 266         sched_foreach(block, node) {
 267                 if (!is_Phi(node))
 268                         break;
 269                 if (arch_get_irn_register(node) != env->reg)
 270                         continue;
 271
 272                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 273                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 274
 275                 if(USES_IS_INFINITE(next_use.time)) {
 276                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 277                         continue;
 278                 }
 279
 280                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 281                         if(outer_loop_allowed || next_use.time < best_time) {
 282                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 283                                      next_use.outermost_loop));
 284
 285                                 if(best_starter != NULL) {
 286                                         /* spill the phi as it is not used */
 287                                         spill_phi(env, best_starter);
 288                                 }
 289                                 best_starter = node;
 290                                 best_time = next_use.time;
 291                                 outer_loop_allowed = 0;
 292                         }
 293                 } else {
 294                         if(outer_loop_allowed && next_use.time < best_time) {
 295                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 296                                      next_use.outermost_loop));
 297                                 if(best_starter != NULL) {
 298                                         /* spill the phi as it is not used */
 299                                         spill_phi(env, best_starter);
 300                                 }
 301                                 best_starter = node;
 302                                 best_time = next_use.time;
 303                         }
 304                 }
 305
 306                 if(best_starter != node) {
 307                         /* spill the phi as it is not used */
 308                         spill_phi(env, best_starter);
 309                 }
 310         }
 311
 312         /* check all Live-Ins */
 313         be_lv_foreach(env->lv, block, be_lv_state_in, i) {
 314                 node = be_lv_get_irn(env->lv, block, i);
 315
 316                 if(!mode_is_data(get_irn_mode(node)))
 317                         continue;
 318
 319                 if (arch_get_irn_register(node) != env->reg)
 320                         continue;
 321
 322                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 323                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 324
 325                 if(USES_IS_INFINITE(next_use.time)) {
 326                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 327                         continue;
 328                 }
 329
 330                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 331                         if(outer_loop_allowed || next_use.time < best_time) {
 332                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 333                                      next_use.outermost_loop));
 334
 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                                 outer_loop_allowed = 0;
 342                         }
 343                 } else {
 344                         if(outer_loop_allowed && next_use.time < best_time) {
 345                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 346                                      next_use.outermost_loop));
 347                                 if(best_starter != NULL && is_Phi(best_starter)) {
 348                                         /* spill the phi as it is not used */
 349                                         spill_phi(env, best_starter);
 350                                 }
 351                                 best_starter = node;
 352                                 best_time = next_use.time;
 353                         }
 354                 }
 355         }
 356
 357         block_info->start_state = best_starter;
 358
 359         return block_info;
 360 }
 361
 362 /**
 363  * For the given block @p block, decide for each values
 364  * whether it is used from a register or is reloaded
 365  * before the use.
 366  */
 367 static
 368 void belady(minibelady_env_t *env, ir_node *block)
 369 {
 370         ir_node *current_state;
 371         ir_node *node;
 372         block_info_t *block_info;
 373
 374         /* Don't do a block twice */
 375         if(irn_visited(block))
 376                 return;
 377
 378         /* compute value to start with */
 379         block_info = compute_block_start_state(env, block);
 380
 381         /* get the starting workset for this block */
 382         DBG((dbg, LEVEL_3, "\n"));
 383         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 384
 385         current_state = block_info->start_state;
 386         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 387
 388         /* process the block from start to end */
 389         DBG((dbg, LEVEL_3, "Processing...\n"));
 390
 391         sched_foreach(block, node) {
 392                 int i, arity;
 393                 ir_node *need_val = NULL;
 394
 395                 /* projs are handled with the tuple value.
 396                  * Phis are no real instr (see insert_starters()) */
 397                 if (is_Proj(node) || is_Phi(node)) {
 398                         continue;
 399                 }
 400
 401                 /* check which state is desired for the node */
 402                 arity = get_irn_arity(node);
 403                 for(i = 0; i < arity; ++i) {
 404                         const arch_register_t *reg;
 405                         ir_node *in = get_irn_n(node, i);
 406
 407                         if(!mode_is_data(get_irn_mode(in)))
 408                                 continue;
 409
 410                         reg = arch_get_irn_register(in);
 411                         if(reg == env->reg) {
 412                                 assert(need_val == NULL);
 413                                 need_val = in;
 414                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 415                         }
 416                 }
 417                 /* create a reload to match state if necessary */
 418                 if(need_val != NULL && need_val != current_state) {
 419                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 420                         create_reload(env, need_val, node, current_state);
 421                         current_state = need_val;
 422                 }
 423
 424                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 425
 426                 /* record state changes by the node */
 427                 if (get_irn_mode(node) == mode_T) {
 428                         const ir_edge_t *edge;
 429
 430                         foreach_out_edge(node, edge) {
 431                                 const arch_register_t *reg;
 432                                 ir_node *proj = get_edge_src_irn(edge);
 433
 434                                 if(!mode_is_data(get_irn_mode(proj)))
 435                                         continue;
 436
 437                                 reg = arch_get_irn_register(proj);
 438                                 if(reg == env->reg) {
 439                                         current_state = proj;
 440                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 441                                 }
 442                         }
 443                 } else {
 444                         if(mode_is_data(get_irn_mode(node))) {
 445                                 const arch_register_t *reg = arch_get_irn_register(node);
 446                                 if(reg == env->reg) {
 447                                         current_state = node;
 448                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 449                                 }
 450                         }
 451                 }
 452         }
 453
 454         /* Remember end-workset for this block */
 455         block_info->end_state = current_state;
 456         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 457 }
 458
 459 static
 460 void belady_walker(ir_node *block, void *data)
 461 {
 462         belady((minibelady_env_t*) data, block);
 463 }
 464
 465 static
 466 ir_node *get_end_of_block_insertion_point(ir_node *block)
 467 {
 468         ir_node *last = sched_last(block);
 469
 470         /* skip Projs and Keep-alikes behind the jump... */
 471         while(is_Proj(last) || be_is_Keep(last)) {
 472                 last = sched_prev(last);
 473         }
 474
 475         if(!is_cfop(last)) {
 476                 last = sched_next(last);
 477                 /* last node must be a cfop, only exception is the start block */
 478                 assert(last     == get_irg_start_block(get_irn_irg(block)));
 479         }
 480
 481         return last;
 482 }
 483
 484 /**
 485  * We must adapt the live-outs to the live-ins at each block-border.
 486  */
 487 static
 488 void fix_block_borders(ir_node *block, void *data) {
 489         minibelady_env_t *env = data;
 490         ir_graph *irg = get_irn_irg(block);
 491         ir_node *startblock = get_irg_start_block(irg);
 492         int i;
 493         int arity;
 494         block_info_t *block_info;
 495
 496         if(block == startblock)
 497                 return;
 498
 499         DBG((dbg, LEVEL_3, "\n"));
 500
 501         block_info = get_block_info(block);
 502
 503         DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
 504              block_info->start_state));
 505
 506         /* process all pred blocks */
 507         arity = get_irn_arity(block);
 508         for (i = 0; i < arity; ++i) {
 509                 ir_node      *pred       = get_Block_cfgpred_block(block, i);
 510                 block_info_t *pred_info  = get_block_info(pred);
 511                 ir_node      *need_state = block_info->start_state;
 512
 513                 if(need_state == NULL)
 514                         continue;
 515
 516                 if(is_Phi(need_state) && get_nodes_block(need_state) == block) {
 517                         need_state = get_irn_n(need_state, i);
 518                 }
 519
 520                 DBG((dbg, LEVEL_3, "  Pred %+F (ends in %+F, we need %+F)\n", pred,
 521                      pred_info->end_state, need_state));
 522
 523                 if(pred_info->end_state != need_state) {
 524                         ir_node *insert_point = get_end_of_block_insertion_point(pred);
 525
 526
 527                         DBG((dbg, LEVEL_3, "  Creating reload for %+F\n", need_state));
 528                         create_reload(env, need_state, insert_point, pred_info->end_state);
 529                 }
 530         }
 531 }
 532
 533 void be_assure_state(be_irg_t *birg, const arch_register_t *reg, void *func_env,
 534                      create_spill_func create_spill,
 535                      create_reload_func create_reload) {
 536         minibelady_env_t env;
 537         ir_graph *irg = be_get_birg_irg(birg);
 538         spill_info_t *info;
 539         be_lv_t *lv = be_assure_liveness(birg);
 540
 541         be_liveness_assure_sets(lv);
 542         /* construct control flow loop tree */
 543         if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
 544                 construct_cf_backedges(irg);
 545         }
 546
 547         obstack_init(&env.obst);
 548         env.reg           = reg;
 549         env.func_env      = func_env;
 550         env.create_spill  = create_spill;
 551         env.create_reload = create_reload;
 552         env.lv            = be_get_birg_liveness(birg);
 553         env.uses          = be_begin_uses(irg, env.lv);
 554         env.spills        = NULL;
 555         ir_nodemap_init(&env.spill_infos);
 556
 557         assure_doms(irg);
 558         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 559         inc_irg_visited(irg);
 560
 561         /* process blocks */
 562         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 563
 564         /* fix block end_states that don't match the next blocks start_state */
 565         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 566
 567         ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 568
 569         /* reconstruct ssa-form */
 570         info = env.spills;
 571         while(info != NULL) {
 572                 be_ssa_construction_env_t senv;
 573                 int i, len;
 574                 ir_node **phis;
 575
 576                 be_ssa_construction_init(&senv, birg);
 577                 if(sched_is_scheduled(info->value))
 578                         be_ssa_construction_add_copy(&senv, info->value);
 579                 be_ssa_construction_add_copies(&senv,
 580                                                info->reloads, ARR_LEN(info->reloads));
 581                 be_ssa_construction_fix_users(&senv, info->value);
 582
 583                 if(lv != NULL) {
 584                         be_ssa_construction_update_liveness_phis(&senv, lv);
 585
 586                         be_liveness_update(lv, info->value);
 587                         len = ARR_LEN(info->reloads);
 588                         for(i = 0; i < len; ++i) {
 589                                 ir_node *reload = info->reloads[i];
 590                                 be_liveness_update(lv, reload);
 591                         }
 592                 }
 593
 594                 phis = be_ssa_construction_get_new_phis(&senv);
 595
 596                 /* set register requirements for phis */
 597                 len = ARR_LEN(phis);
 598                 for(i = 0; i < len; ++i) {
 599                         ir_node *phi = phis[i];
 600                         arch_set_irn_register(phi, env.reg);
 601                 }
 602                 be_ssa_construction_destroy(&senv);
 603
 604                 info = info->next;
 605         }
 606
 607         /* some nodes might be dead now. */
 608         be_remove_dead_nodes_from_schedule(birg);
 609
 610         ir_nodemap_destroy(&env.spill_infos);
 611         be_end_uses(env.uses);
 612         obstack_free(&env.obst, NULL);
 613 }
 614
 615 void be_init_state(void)
 616 {
 617         FIRM_DBG_REGISTER(dbg, "firm.be.state");
 618 }
 619
 620 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);