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         }
 139
 140         if(sched_is_scheduled(state)) {
 141                 next = state;
 142                 do {
 143                         after = next;
 144                         next = sched_next(after);
 145                 } while(is_Proj(next) || is_Phi(next) || be_is_Keep(next));
 146         } else {
 147                 after = state;
 148         }
 149         spill_info->spill = env->create_spill(env->func_env, state, force, after);
 150
 151         return spill_info;
 152 }
 153
 154 static
 155 void create_reload(minibelady_env_t *env, ir_node *state, ir_node *before,
 156                    ir_node *last_state)
 157 {
 158         spill_info_t *spill_info = create_spill(env, state, 0);
 159         ir_node *spill = spill_info->spill;
 160         ir_node *reload;
 161
 162         reload = env->create_reload(env->func_env, state, spill, before,
 163                                     last_state);
 164         ARR_APP1(ir_node*, spill_info->reloads, reload);
 165 }
 166
 167 static
 168 void spill_phi(minibelady_env_t *env, ir_node *phi)
 169 {
 170         ir_graph *irg = get_irn_irg(phi);
 171         ir_node *block = get_nodes_block(phi);
 172         int i, arity = get_irn_arity(phi);
 173         ir_node **in = alloca(arity * sizeof(in[0]));
 174         ir_node *spill_to_kill = NULL;
 175         spill_info_t *spill_info;
 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_Bad(irg);
 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(irg, 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(env->arch_env, 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 (arch_get_irn_register(env->arch_env, node) != env->reg)
 317                         continue;
 318
 319                 DBG((dbg, LEVEL_2, "\t...checking %+F\n", node));
 320                 next_use = be_get_next_use(env->uses, first, 0, node, 0);
 321
 322                 if(USES_IS_INFINITE(next_use.time)) {
 323                         DBG((dbg, LEVEL_2, "\tnot taken (dead)\n"));
 324                         continue;
 325                 }
 326
 327                 if(next_use.outermost_loop >= get_loop_depth(loop)) {
 328                         if(outer_loop_allowed || next_use.time < best_time) {
 329                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 330                                      next_use.outermost_loop));
 331
 332                                 if(best_starter != NULL && is_Phi(best_starter)) {
 333                                         /* spill the phi as it is not used */
 334                                         spill_phi(env, best_starter);
 335                                 }
 336                                 best_starter = node;
 337                                 best_time = next_use.time;
 338                                 outer_loop_allowed = 0;
 339                         }
 340                 } else {
 341                         if(outer_loop_allowed && next_use.time < best_time) {
 342                                 DBG((dbg, LEVEL_2, "\ttaken (%u, loop %d)\n", next_use.time,
 343                                      next_use.outermost_loop));
 344                                 if(best_starter != NULL && is_Phi(best_starter)) {
 345                                         /* spill the phi as it is not used */
 346                                         spill_phi(env, best_starter);
 347                                 }
 348                                 best_starter = node;
 349                                 best_time = next_use.time;
 350                         }
 351                 }
 352         }
 353
 354         block_info->start_state = best_starter;
 355
 356         return block_info;
 357 }
 358
 359 /**
 360  * For the given block @p block, decide for each values
 361  * whether it is used from a register or is reloaded
 362  * before the use.
 363  */
 364 static
 365 void belady(minibelady_env_t *env, ir_node *block)
 366 {
 367         ir_node *current_state;
 368         ir_node *node;
 369         block_info_t *block_info;
 370
 371         /* Don't do a block twice */
 372         if(irn_visited(block))
 373                 return;
 374
 375         /* compute value to start with */
 376         block_info = compute_block_start_state(env, block);
 377
 378         /* get the starting workset for this block */
 379         DBG((dbg, LEVEL_3, "\n"));
 380         DBG((dbg, LEVEL_3, "Decide for %+F\n", block));
 381
 382         current_state = block_info->start_state;
 383         DBG((dbg, LEVEL_3, "Start value: %+F\n", current_state));
 384
 385         /* process the block from start to end */
 386         DBG((dbg, LEVEL_3, "Processing...\n"));
 387
 388         sched_foreach(block, node) {
 389                 int i, arity;
 390                 ir_node *need_val = NULL;
 391
 392                 /* projs are handled with the tuple value.
 393                  * Phis are no real instr (see insert_starters()) */
 394                 if (is_Proj(node) || is_Phi(node)) {
 395                         continue;
 396                 }
 397
 398                 /* check which state is desired for the node */
 399                 arity = get_irn_arity(node);
 400                 for(i = 0; i < arity; ++i) {
 401                         ir_node *in = get_irn_n(node, i);
 402                         const arch_register_t *reg =
 403                                 arch_get_irn_register(env->arch_env, in);
 404                         if(reg == env->reg) {
 405                                 assert(need_val == NULL);
 406                                 need_val = in;
 407                                 DBG((dbg, LEVEL_3, "\t... need state %+F\n", need_val));
 408                         }
 409                 }
 410                 /* create a reload to match state if necessary */
 411                 if(need_val != NULL && need_val != current_state) {
 412                         DBG((dbg, LEVEL_3, "\t... reloading %+F\n", need_val));
 413                         create_reload(env, need_val, node, current_state);
 414                         current_state = need_val;
 415                 }
 416
 417                 DBG((dbg, LEVEL_3, "  ...%+F\n", node));
 418
 419                 /* record state changes by the node */
 420                 if (get_irn_mode(node) == mode_T) {
 421                         const ir_edge_t *edge;
 422
 423                         foreach_out_edge(node, edge) {
 424                                 ir_node *proj = get_edge_src_irn(edge);
 425                                 const arch_register_t *reg =
 426                                         arch_get_irn_register(env->arch_env, proj);
 427                                 if(reg == env->reg) {
 428                                         current_state = proj;
 429                                         DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 430                                 }
 431                         }
 432                 } else {
 433                         const arch_register_t *reg =
 434                                 arch_get_irn_register(env->arch_env, node);
 435                         if(reg == env->reg) {
 436                                 current_state = node;
 437                                 DBG((dbg, LEVEL_3, "\t... current_state <- %+F\n", current_state));
 438                         }
 439                 }
 440         }
 441
 442         /* Remember end-workset for this block */
 443         block_info->end_state = current_state;
 444         DBG((dbg, LEVEL_3, "End value for %+F: %+F\n", block, current_state));
 445 }
 446
 447 static
 448 void belady_walker(ir_node *block, void *data)
 449 {
 450         belady((minibelady_env_t*) data, block);
 451 }
 452
 453 static
 454 ir_node *get_end_of_block_insertion_point(ir_node *block)
 455 {
 456         ir_node *last = sched_last(block);
 457
 458         /* skip Projs and Keep-alikes behind the jump... */
 459         while(is_Proj(last) || be_is_Keep(last)) {
 460                 last = sched_prev(last);
 461         }
 462
 463         if(!is_cfop(last)) {
 464                 last = sched_next(last);
 465                 /* last node must be a cfop, only exception is the start block */
 466                 assert(last     == get_irg_start_block(get_irn_irg(block)));
 467         }
 468
 469         return last;
 470 }
 471
 472 /**
 473  * We must adapt the live-outs to the live-ins at each block-border.
 474  */
 475 static
 476 void fix_block_borders(ir_node *block, void *data) {
 477         minibelady_env_t *env = data;
 478         ir_graph *irg = get_irn_irg(block);
 479         ir_node *startblock = get_irg_start_block(irg);
 480         int i;
 481         int arity;
 482         block_info_t *block_info;
 483
 484         if(block == startblock)
 485                 return;
 486
 487         DBG((dbg, LEVEL_3, "\n"));
 488
 489         block_info = get_block_info(block);
 490
 491         DBG((dbg, LEVEL_3, "Fixing %+F (needs %+F)\n", block,
 492              block_info->start_state));
 493
 494         /* process all pred blocks */
 495         arity = get_irn_arity(block);
 496         for (i = 0; i < arity; ++i) {
 497                 ir_node      *pred       = get_Block_cfgpred_block(block, i);
 498                 block_info_t *pred_info  = get_block_info(pred);
 499                 ir_node      *need_state = block_info->start_state;
 500
 501                 if(need_state == NULL)
 502                         continue;
 503
 504                 if(is_Phi(need_state) && get_nodes_block(need_state) == block) {
 505                         need_state = get_irn_n(need_state, i);
 506                 }
 507
 508                 DBG((dbg, LEVEL_3, "  Pred %+F (ends in %+F, we need %+F)\n", pred,
 509                      pred_info->end_state, need_state));
 510
 511                 if(pred_info->end_state != need_state) {
 512                         ir_node *insert_point = get_end_of_block_insertion_point(pred);
 513
 514
 515                         DBG((dbg, LEVEL_3, "  Creating reload for %+F\n", need_state));
 516                         create_reload(env, need_state, insert_point, pred_info->end_state);
 517                 }
 518         }
 519 }
 520
 521 void be_assure_state(be_irg_t *birg, const arch_register_t *reg, void *func_env,
 522                      create_spill_func create_spill,
 523                      create_reload_func create_reload) {
 524         minibelady_env_t env;
 525         ir_graph *irg = be_get_birg_irg(birg);
 526         spill_info_t *info;
 527         be_lv_t *lv = be_assure_liveness(birg);
 528
 529         be_liveness_assure_sets(lv);
 530         be_assure_dom_front(birg);
 531         /* construct control flow loop tree */
 532         if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
 533                 construct_cf_backedges(irg);
 534         }
 535
 536         obstack_init(&env.obst);
 537         env.arch_env      = be_get_birg_arch_env(birg);
 538         env.reg           = reg;
 539         env.func_env      = func_env;
 540         env.create_spill  = create_spill;
 541         env.create_reload = create_reload;
 542         env.lv            = be_get_birg_liveness(birg);
 543         env.uses          = be_begin_uses(irg, env.lv);
 544         env.spills        = NULL;
 545         ir_nodemap_init(&env.spill_infos);
 546
 547         assure_doms(irg);
 548         set_using_visited(irg);
 549         set_using_irn_link(irg);
 550         inc_irg_visited(irg);
 551
 552         /* process blocks */
 553         irg_block_walk_graph(irg, NULL, belady_walker, &env);
 554
 555         /* fix block end_states that don't match the next blocks start_state */
 556         irg_block_walk_graph(irg, fix_block_borders, NULL, &env);
 557
 558         clear_using_visited(irg);
 559         clear_using_irn_link(irg);
 560
 561         /* reconstruct ssa-form */
 562         info = env.spills;
 563         while(info != NULL) {
 564                 be_ssa_construction_env_t senv;
 565                 int i, len;
 566                 ir_node **phis;
 567
 568                 be_ssa_construction_init(&senv, birg);
 569                 if(sched_is_scheduled(info->value))
 570                         be_ssa_construction_add_copy(&senv, info->value);
 571                 be_ssa_construction_add_copies(&senv,
 572                                                info->reloads, ARR_LEN(info->reloads));
 573                 be_ssa_construction_fix_users(&senv, info->value);
 574
 575                 if(lv != NULL) {
 576                         be_ssa_construction_update_liveness_phis(&senv, lv);
 577
 578                         be_liveness_update(lv, info->value);
 579                         len = ARR_LEN(info->reloads);
 580                         for(i = 0; i < len; ++i) {
 581                                 ir_node *reload = info->reloads[i];
 582                                 be_liveness_update(lv, reload);
 583                         }
 584                 }
 585
 586                 phis = be_ssa_construction_get_new_phis(&senv);
 587
 588                 /* set register requirements for phis */
 589                 len = ARR_LEN(phis);
 590                 for(i = 0; i < len; ++i) {
 591                         ir_node *phi = phis[i];
 592                         be_set_phi_flags(env.arch_env, phi, arch_irn_flags_ignore);
 593                         arch_set_irn_register(env.arch_env, phi, env.reg);
 594                 }
 595                 be_ssa_construction_destroy(&senv);
 596
 597                 info = info->next;
 598         }
 599
 600         /* some nodes might be dead now. */
 601         be_remove_dead_nodes_from_schedule(birg);
 602
 603         ir_nodemap_destroy(&env.spill_infos);
 604         be_end_uses(env.uses);
 605         obstack_free(&env.obst, NULL);
 606 }
 607
 608 void be_init_state(void)
 609 {
 610         FIRM_DBG_REGISTER(dbg, "firm.be.state");
 611 }
 612
 613 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_state);