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 i, arity = get_irn_arity(phi);
 172         ir_node **in = alloca(arity * sizeof(in[0]));
 173         ir_node *spill_to_kill = NULL;
 174         spill_info_t *spill_info;
 175
 176         /* does a spill exist for the phis value? */
 177         spill_info = get_spill_info(env, phi);
 178         if(spill_info != NULL) {
 179                 spill_to_kill = spill_info->spill;
 180         } else {
 181                 spill_info = create_spill_info(env, phi);
 182         }
 183
 184         /* create a new phi-M with bad preds */
 185         for(i = 0; i < arity; ++i) {
 186                 in[i] = new_r_Unknown(irg, mode_M);
 187         }
 188
 189         DBG((dbg, LEVEL_2, "\tcreate Phi-M for %+F\n", phi));
 190
 191         /* create a Phi-M */
 192         spill_info->spill = new_r_Phi(irg, block, arity, in, mode_M);
 193
 194         if(spill_to_kill != NULL) {
 195                 exchange(spill_to_kill, spill_info->spill);
 196                 sched_remove(spill_to_kill);
 197         }
 198
 199         /* create spills for the phi values */
 200         for(i = 0; i < arity; ++i) {
 201                 ir_node *in = get_irn_n(phi, i);
 202                 spill_info_t *pred_spill = create_spill(env, in, 1);
 203                 set_irn_n(spill_info->spill, i, pred_spill->spill);
 204         }
 205 }
 206
 207 static
 208 void belady(minibelady_env_t *env, ir_node *block);
 209
 210 /**
 211  * Collects all values live-in at block @p block and all phi results in this
 212  * block.
 213  * Then it adds the best values (at most n_regs) to the blocks start_workset.
 214  * The phis among the remaining values get spilled: Introduce psudo-copies of
 215  * their args to break interference and make it possible to spill them to the
 216  * same spill slot.
 217  */
 218 static
 219 block_info_t *compute_block_start_state(minibelady_env_t *env, ir_node *block)
 220 {
 221         block_info_t  *block_info;
 222         be_next_use_t  next_use;
 223         ir_loop       *loop;
 224         ir_node       *best_starter, *first;
 225         ir_node       *node;
 226         int            n_cfgpreds;
 227         unsigned       best_time;
 228         int            outer_loop_allowed;
 229         int            i;
 230
 231         /* Create the block info for this block. */
 232         block_info = new_block_info(&env->obst, block);
 233         n_cfgpreds = get_Block_n_cfgpreds(block);
 234
 235         /* no cfgpred -> no value active */
 236         if(n_cfgpreds == 0) {
 237                 block_info->start_state = NULL;
 238                 return block_info;
 239         }
 240
 241         /* for 1 pred only: simply take the the end-state of the pred */
 242         if(n_cfgpreds == 1) {
 243                 ir_node *pred_block = get_Block_cfgpred_block(block, 0);
 244                 block_info_t *pred_info;
 245
 246                 /* process pred block */
 247                 belady(env, pred_block);
 248
 249                 pred_info = get_block_info(pred_block);
 250
 251                 DBG((dbg, LEVEL_2, "Taking end state from %+F: %+F\n", pred_block, pred_info->end_state));
 252                 block_info->start_state = pred_info->end_state;
 253                 return block_info;
 254         }
 255
 256         /* Collect all values living at start of block */
 257         DBG((dbg, LEVEL_2, "Living at start of %+F:\n", block));
 258         first = sched_first(block);
 259         loop = get_irn_loop(block);
 260         best_starter = NULL;
 261         best_time = USES_INFINITY;
 262         outer_loop_allowed = 1;
 263
 264         /* check all Phis first */
 265         sched_foreach(block, node) {
 266                 if (!is_Phi(node))
 267                         break;
 268                 if (arch_get_irn_register(node) != env->reg)
 269                         continue;
 270
 271                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 272                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 273
 274                 if(USES_IS_INFINITE(next_use.time)) {
 275                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 276                         continue;
 277                 }
 278
 279                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 280                         if(outer_loop_allowed || next_use.time < best_time) {
 281                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 282                                      next_use.outermost_loop));
 283
 284                                 if(best_starter != NULL) {
 285                                         /* spill the phi as it is not used */
 286                                         spill_phi(env, best_starter);
 287                                 }
 288                                 best_starter = node;
 289                                 best_time = next_use.time;
 290                                 outer_loop_allowed = 0;
 291                         }
 292                 } else {
 293                         if(outer_loop_allowed && next_use.time < best_time) {
 294                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 295                                      next_use.outermost_loop));
 296                                 if(best_starter != NULL) {
 297                                         /* spill the phi as it is not used */
 298                                         spill_phi(env, best_starter);
 299                                 }
 300                                 best_starter = node;
 301                                 best_time = next_use.time;
 302                         }
 303                 }
 304
 305                 if(best_starter != node) {
 306                         /* spill the phi as it is not used */
 307                         spill_phi(env, best_starter);
 308                 }
 309         }
 310
 311         /* check all Live-Ins */
 312         be_lv_foreach(env->lv, block, be_lv_state_in, i) {
 313                 node = be_lv_get_irn(env->lv, block, i);
 314
 315                 if(!mode_is_data(get_irn_mode(node)))
 316                         continue;
 317
 318                 if (arch_get_irn_register(node) != env->reg)
 319                         continue;
 320
 321                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 322                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 323
 324                 if(USES_IS_INFINITE(next_use.time)) {
 325                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 326                         continue;
 327                 }
 328
 329                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 330                         if(outer_loop_allowed || next_use.time < best_time) {
 331                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 332                                      next_use.outermost_loop));
 333
 334                                 if(best_starter != NULL && is_Phi(best_starter)) {
 335                                         /* spill the phi as it is not used */
 336                                         spill_phi(env, best_starter);
 337                                 }
 338                                 best_starter = node;
 339                                 best_time = next_use.time;
 340                                 outer_loop_allowed = 0;
 341                         }
 342                 } else {
 343                         if(outer_loop_allowed && next_use.time < best_time) {
 344                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 345                                      next_use.outermost_loop));
 346                                 if(best_starter != NULL && is_Phi(best_starter)) {
 347                                         /* spill the phi as it is not used */
 348                                         spill_phi(env, best_starter);
 349                                 }
 350                                 best_starter = node;
 351                                 best_time = next_use.time;
 352                         }
 353                 }
 354         }
 355
 356         block_info->start_state = best_starter;
 357
 358         return block_info;
 359 }
 360
 361 /**
 362  * For the given block @p block, decide for each values
 363  * whether it is used from a register or is reloaded
 364  * before the use.
 365  */
 366 static
 367 void belady(minibelady_env_t *env, ir_node *block)
 368 {
 369         ir_node *current_state;
 370         ir_node *node;
 371         block_info_t *block_info;
 372
 373         /* Don't do a block twice */
 374         if(irn_visited(block))
 375                 return;
 376
 377         /* compute value to start with */
 378         block_info = compute_block_start_state(env, block);
 379
 380         /* get the starting workset for this block */
 381         DBG((dbg, LEVEL_3, "\n"));
 382         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 383
 384         current_state = block_info->start_state;
 385         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 386
 387         /* process the block from start to end */
 388         DBG((dbg, LEVEL_3, "Processing...\n"));
 389
 390         sched_foreach(block, node) {
 391                 int i, arity;
 392                 ir_node *need_val = NULL;
 393
 394                 /* projs are handled with the tuple value.
 395                  * Phis are no real instr (see insert_starters()) */
 396                 if (is_Proj(node) || is_Phi(node)) {
 397                         continue;
 398                 }
 399
 400                 /* check which state is desired for the node */
 401                 arity = get_irn_arity(node);
 402                 for(i = 0; i < arity; ++i) {
 403                         const arch_register_t *reg;
 404                         ir_node *in = get_irn_n(node, i);
 405
 406                         if(!mode_is_data(get_irn_mode(in)))
 407                                 continue;
 408
 409                         reg = arch_get_irn_register(in);
 410                         if(reg == env->reg) {
 411                                 assert(need_val == NULL);
 412                                 need_val = in;
 413                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 414                         }
 415                 }
 416                 /* create a reload to match state if necessary */
 417                 if(need_val != NULL && need_val != current_state) {
 418                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 419                         create_reload(env, need_val, node, current_state);
 420                         current_state = need_val;
 421                 }
 422
 423                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 424
 425                 /* record state changes by the node */
 426                 if (get_irn_mode(node) == mode_T) {
 427                         const ir_edge_t *edge;
 428
 429                         foreach_out_edge(node, edge) {
 430                                 const arch_register_t *reg;
 431                                 ir_node *proj = get_edge_src_irn(edge);
 432
 433                                 if(!mode_is_data(get_irn_mode(proj)))
 434                                         continue;
 435
 436                                 reg = arch_get_irn_register(proj);
 437                                 if(reg == env->reg) {
 438                                         current_state = proj;
 439                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 440                                 }
 441                         }
 442                 } else {
 443                         if(mode_is_data(get_irn_mode(node))) {
 444                                 const arch_register_t *reg = arch_get_irn_register(node);
 445                                 if(reg == env->reg) {
 446                                         current_state = node;
 447                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 448                                 }
 449                         }
 450                 }
 451         }
 452
 453         /* Remember end-workset for this block */
 454         block_info->end_state = current_state;
 455         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 456 }
 457
 458 static
 459 void belady_walker(ir_node *block, void *data)
 460 {
 461         belady((minibelady_env_t*) data, block);
 462 }
 463
 464 static
 465 ir_node *get_end_of_block_insertion_point(ir_node *block)
 466 {
 467         ir_node *last = sched_last(block);
 468
 469         /* skip Projs and Keep-alikes behind the jump... */
 470         while(is_Proj(last) || be_is_Keep(last)) {
 471                 last = sched_prev(last);
 472         }
 473
 474         if(!is_cfop(last)) {
 475                 last = sched_next(last);
 476                 /* last node must be a cfop, only exception is the start block */
 477                 assert(last     == get_irg_start_block(get_irn_irg(block)));
 478         }
 479
 480         return last;
 481 }
 482
 483 /**
 484  * We must adapt the live-outs to the live-ins at each block-border.
 485  */
 486 static
 487 void fix_block_borders(ir_node *block, void *data) {
 488         minibelady_env_t *env = data;
 489         ir_graph *irg = get_irn_irg(block);
 490         ir_node *startblock = get_irg_start_block(irg);
 491         int i;
 492         int arity;
 493         block_info_t *block_info;
 494
 495         if(block == startblock)
 496                 return;
 497
 498         DBG((dbg, LEVEL_3, "\n"));
 499
 500         block_info = get_block_info(block);
 501
 502         DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
 503              block_info->start_state));
 504
 505         /* process all pred blocks */
 506         arity = get_irn_arity(block);
 507         for (i = 0; i < arity; ++i) {
 508                 ir_node      *pred       = get_Block_cfgpred_block(block, i);
 509                 block_info_t *pred_info  = get_block_info(pred);
 510                 ir_node      *need_state = block_info->start_state;
 511
 512                 if(need_state == NULL)
 513                         continue;
 514
 515                 if(is_Phi(need_state) && get_nodes_block(need_state) == block) {
 516                         need_state = get_irn_n(need_state, i);
 517                 }
 518
 519                 DBG((dbg, LEVEL_3, "  Pred %+F (ends in %+F, we need %+F)\n", pred,
 520                      pred_info->end_state, need_state));
 521
 522                 if(pred_info->end_state != need_state) {
 523                         ir_node *insert_point = get_end_of_block_insertion_point(pred);
 524
 525
 526                         DBG((dbg, LEVEL_3, "  Creating reload for %+F\n", need_state));
 527                         create_reload(env, need_state, insert_point, pred_info->end_state);
 528                 }
 529         }
 530 }
 531
 532 void be_assure_state(be_irg_t *birg, const arch_register_t *reg, void *func_env,
 533                      create_spill_func create_spill,
 534                      create_reload_func create_reload) {
 535         minibelady_env_t env;
 536         ir_graph *irg = be_get_birg_irg(birg);
 537         spill_info_t *info;
 538         be_lv_t *lv = be_assure_liveness(birg);
 539
 540         be_liveness_assure_sets(lv);
 541         /* construct control flow loop tree */
 542         if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
 543                 construct_cf_backedges(irg);
 544         }
 545
 546         obstack_init(&env.obst);
 547         env.reg           = reg;
 548         env.func_env      = func_env;
 549         env.create_spill  = create_spill;
 550         env.create_reload = create_reload;
 551         env.lv            = be_get_birg_liveness(birg);
 552         env.uses          = be_begin_uses(irg, env.lv);
 553         env.spills        = NULL;
 554         ir_nodemap_init(&env.spill_infos);
 555
 556         assure_doms(irg);
 557         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 558         inc_irg_visited(irg);
 559
 560         /* process blocks */
 561         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 562
 563         /* fix block end_states that don't match the next blocks start_state */
 564         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 565
 566         ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK);
 567
 568         /* reconstruct ssa-form */
 569         info = env.spills;
 570         while(info != NULL) {
 571                 be_ssa_construction_env_t senv;
 572                 int i, len;
 573                 ir_node **phis;
 574
 575                 be_ssa_construction_init(&senv, birg);
 576                 if(sched_is_scheduled(info->value))
 577                         be_ssa_construction_add_copy(&senv, info->value);
 578                 be_ssa_construction_add_copies(&senv,
 579                                                info->reloads, ARR_LEN(info->reloads));
 580                 be_ssa_construction_fix_users(&senv, info->value);
 581
 582                 if(lv != NULL) {
 583                         be_ssa_construction_update_liveness_phis(&senv, lv);
 584
 585                         be_liveness_update(lv, info->value);
 586                         len = ARR_LEN(info->reloads);
 587                         for(i = 0; i < len; ++i) {
 588                                 ir_node *reload = info->reloads[i];
 589                                 be_liveness_update(lv, reload);
 590                         }
 591                 }
 592
 593                 phis = be_ssa_construction_get_new_phis(&senv);
 594
 595                 /* set register requirements for phis */
 596                 len = ARR_LEN(phis);
 597                 for(i = 0; i < len; ++i) {
 598                         ir_node *phi = phis[i];
 599                         be_set_phi_flags(phi, arch_irn_flags_ignore);
 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);