nsz Git - libfirm/blob - ir/be/bessaconstr.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       SSA construction for a set of nodes
  23  * @author      Sebastian Hack, Daniel Grund, Matthias Braun, Christian Wuerdig,
  24  *              Sebastian Buchwald
  25  * @date        04.05.2005
  26  * @version     $Id$
  27  *
  28  * The problem: Given a value and a set of "copies" that are known to
  29  * represent the same abstract value, rewire all usages of the original value
  30  * to their closest copy while introducing phis as necessary.
  31  *
  32  * Algorithm: Mark all blocks in the iterated dominance frontiers of the value
  33  * and its copies. Link the copies ordered by dominance to the blocks.  Then
  34  * we search for each use all definitions in the current block, if none is
  35  * found, then we search one in the immediate dominator. If we are in a block
  36  * of the dominance frontier, create a phi and do the same search for all
  37  * phi arguments.
  38  *
  39  * A copy in this context means, that you want to introduce several new
  40  * abstract values (in Firm: nodes) for which you know, that they
  41  * represent the same concrete value. This is the case if you
  42  * - copy
  43  * - spill and reload
  44  * - re-materialize
  45  * a value.
  46  *
  47  * This function reroutes all uses of the original value to the copies in the
  48  * corresponding dominance subtrees and creates Phi functions where necessary.
  49  */
  50 #include "config.h"
  51
  52 /* statev in this file is extensive, so only enable if needed */
  53 #define DISABLE_STATEV
  54
  55 #include "bessaconstr.h"
  56 #include "bemodule.h"
  57 #include "besched.h"
  58 #include "beintlive_t.h"
  59 #include "beirg.h"
  60 #include "be_t.h"
  61 #include "benode.h"
  62
  63 #include "debug.h"
  64 #include "error.h"
  65 #include "pdeq.h"
  66 #include "array.h"
  67 #include "irdom.h"
  68 #include "irnodeset.h"
  69
  70 #include "ircons.h"
  71 #include "iredges_t.h"
  72
  73 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  74
  75 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
  76                                         ir_node *block);
  77
  78 struct constr_info {
  79         bool is_definition     : 1;
  80         bool is_use            : 1;
  81         bool already_processed : 1;
  82         union {
  83                 /* Since we only consider scheduled nodes,
  84                  * this points to the real definition (e.g. a Proj). */
  85                 ir_node *definition;
  86
  87                 /* Last definition of a block. */
  88                 ir_node *last_definition;
  89         };
  90 };
  91
  92 typedef struct constr_info constr_info;
  93
  94 /**
  95  * @return Whether the block contains a definition.
  96  */
  97 static bool has_definition(const ir_node *block)
  98 {
  99         return irn_visited(block);
 100 }
 101
 102 static constr_info *get_or_set_info(be_ssa_construction_env_t *env,
 103                                     const ir_node *node)
 104 {
 105         constr_info *info = ir_nodemap_get(&env->infos, node);
 106         if (info == NULL) {
 107                 info = OALLOCZ(&env->obst, constr_info);
 108                 ir_nodemap_insert(&env->infos, node, info);
 109         }
 110         return info;
 111 }
 112
 113 static constr_info *get_info(const be_ssa_construction_env_t *env,
 114                              const ir_node *node)
 115 {
 116         return (constr_info*)ir_nodemap_get(&env->infos, node);
 117 }
 118
 119 /**
 120  * @return Whether the block contains a use.
 121  */
 122 static inline bool has_use(be_ssa_construction_env_t *env, ir_node *block)
 123 {
 124         constr_info *info = get_or_set_info(env, block);
 125         return info->is_use;
 126 }
 127
 128 /**
 129  * @return Whether the node is a definition.
 130  */
 131 static bool is_definition(be_ssa_construction_env_t *env, ir_node *node)
 132 {
 133         constr_info *info = get_info(env, node);
 134         return info != NULL && info->is_definition;
 135 }
 136
 137 /**
 138  * @return Whether the node is a use.
 139  */
 140 static bool is_use(const be_ssa_construction_env_t *env, ir_node *node)
 141 {
 142         constr_info *info = get_info(env, node);
 143         return info != NULL && info->is_use;
 144 }
 145
 146 /**
 147  * Introduces a definition at the corresponding block.
 148  */
 149 static void introduce_definition(be_ssa_construction_env_t *env, ir_node *def)
 150 {
 151         ir_node     *block      = get_nodes_block(def);
 152         constr_info *def_info   = get_or_set_info(env, def);
 153         ir_node     *skip       = skip_Proj(def);
 154         constr_info *skip_info  = get_or_set_info(env, skip);
 155         constr_info *block_info = get_or_set_info(env, block);
 156
 157         DBG((dbg, LEVEL_2, "\tintroducing definition %+F in %+F\n", def, block));
 158
 159         def_info->is_definition = true;
 160
 161         skip_info->is_definition = true;
 162         skip_info->definition    = def;
 163
 164         // Set the last definition if we only introduce one definition for the block
 165         if (has_definition(block)) {
 166                 assert(!block_info->already_processed);
 167                 block_info->last_definition = NULL;
 168         } else {
 169                 mark_irn_visited(block);
 170                 block_info->last_definition = def;
 171         }
 172 }
 173
 174 static void introduce_use(be_ssa_construction_env_t *env, ir_node *use)
 175 {
 176         ir_node     *block      = get_nodes_block(use);
 177         constr_info *info       = get_or_set_info(env, use);
 178         constr_info *block_info = get_or_set_info(env, block);
 179
 180         DBG((dbg, LEVEL_2, "\tintroducing use %+F in %+F\n", use, block));
 181
 182         info->is_use       = true;
 183         block_info->is_use = true;
 184
 185         waitq_put(env->worklist, use);
 186 }
 187
 188 /**
 189  * Calculates the iterated dominance frontier of a set of blocks. Marks the
 190  * blocks as visited. Sets the link fields of the blocks in the dominance
 191  * frontier to the block itself.
 192  */
 193 static void mark_iterated_dominance_frontiers(
 194                                            const be_ssa_construction_env_t *env)
 195 {
 196         stat_ev_cnt_decl(blocks);
 197         DBG((dbg, LEVEL_3, "Dominance Frontier:"));
 198         stat_ev_tim_push();
 199         while (!waitq_empty(env->worklist)) {
 200                 int i;
 201                 ir_node  *block    = (ir_node*)waitq_get(env->worklist);
 202                 ir_node **domfront = be_get_dominance_frontier(env->domfronts, block);
 203                 int domfront_len = ARR_LEN(domfront);
 204
 205                 for (i = 0; i < domfront_len; ++i) {
 206                         ir_node *y = domfront[i];
 207                         if (Block_block_visited(y))
 208                                 continue;
 209
 210                         if (!irn_visited(y)) {
 211                                 set_irn_link(y, NULL);
 212                                 waitq_put(env->worklist, y);
 213                         }
 214
 215                         DBG((dbg, LEVEL_3, " %+F", y));
 216                         mark_Block_block_visited(y);
 217                         stat_ev_cnt_inc(blocks);
 218                 }
 219         }
 220         stat_ev_tim_pop("bessaconstr_idf_time");
 221         stat_ev_cnt_done(blocks, "bessaconstr_idf_blocks");
 222         DBG((dbg, LEVEL_3, "\n"));
 223 }
 224
 225 /**
 226  * Inserts a new phi at the given block.
 227  *
 228  * The constructed phi has only Dummy operands,
 229  * but can be used as definition for other nodes.
 230  *
 231  * @see fix_phi_arguments
 232  */
 233 static ir_node *insert_dummy_phi(be_ssa_construction_env_t *env, ir_node *block)
 234 {
 235         int i, n_preds = get_Block_n_cfgpreds(block);
 236         ir_graph *irg = get_Block_irg(block);
 237         ir_node **ins = ALLOCAN(ir_node*, n_preds);
 238         ir_node  *dummy;
 239         ir_node  *phi;
 240
 241         DBG((dbg, LEVEL_3, "\t...create phi at block %+F\n", block));
 242
 243         assert(n_preds > 1);
 244
 245         dummy = new_r_Dummy(irg, env->mode);
 246         for (i = 0; i < n_preds; ++i) {
 247                 ins[i] = dummy;
 248         }
 249         phi = be_new_Phi(block, n_preds, ins, env->mode, env->phi_cls);
 250         sched_add_after(block, phi);
 251         ARR_APP1(ir_node*, env->new_phis, phi);
 252
 253         DBG((dbg, LEVEL_2, "\tcreating phi %+F in %+F\n", phi, block));
 254         introduce_definition(env, phi);
 255
 256         waitq_put(env->worklist, phi);
 257
 258         return phi;
 259 }
 260
 261 /**
 262  * @return Last definition of the immediate dominator.
 263  */
 264 static ir_node *get_def_at_idom(be_ssa_construction_env_t *env, ir_node *block)
 265 {
 266         ir_node *dom = get_Block_idom(block);
 267         assert(dom != NULL);
 268         DBG((dbg, LEVEL_3, "\t...continue at idom %+F\n", dom));
 269         return search_def_end_of_block(env, dom);
 270 }
 271
 272 /**
 273  * Fixes all operands of a use.
 274  *
 275  * If an operand of the use is a (original) definition,
 276  * it will be replaced by the given definition.
 277  */
 278 static void set_operands(be_ssa_construction_env_t *env, ir_node *use, ir_node *def)
 279 {
 280         constr_info *info  = get_info(env, use);
 281         int          arity = get_irn_arity(use);
 282         int          i;
 283
 284         for (i = 0; i < arity; ++i) {
 285                 ir_node *op = get_irn_n(use, i);
 286
 287                 if (is_definition(env, op)) {
 288                         DBG((dbg, LEVEL_1, "\t...%+F(%d) -> %+F\n", use, i, def));
 289                         set_irn_n(use, i, def);
 290                 }
 291         }
 292
 293         info->already_processed = true;
 294 }
 295
 296 /**
 297  * Fixes all uses of the given block.
 298  */
 299 static void process_block(be_ssa_construction_env_t *env, ir_node *block)
 300 {
 301         ir_node     *node;
 302         ir_node     *def        = NULL;
 303         constr_info *block_info = get_or_set_info(env, block);
 304
 305         assert(has_definition(block));
 306         assert(!block_info->already_processed && "Block already processed");
 307
 308         DBG((dbg, LEVEL_3, "\tprocessing block  %+F\n", block));
 309
 310         sched_foreach(block, node) {
 311                 if (is_use(env, node) && !is_Phi(node)) {
 312                         DBG((dbg, LEVEL_3, "\t...found use %+F\n", node));
 313
 314                         if (def == NULL) {
 315                                 /* Create a phi if the block is in the dominance frontier. */
 316                                 if (Block_block_visited(block)) {
 317                                         def = insert_dummy_phi(env, block);
 318                                 }
 319                                 else {
 320                                         def = get_def_at_idom(env, block);
 321                                 }
 322                         }
 323
 324                         set_operands(env, node, def);
 325                 }
 326
 327                 if (is_definition(env, node)) {
 328                         constr_info *info = get_info(env, node);
 329                         def = info->definition;
 330                         DBG((dbg, LEVEL_3, "\t...found definition %+F\n", def));
 331                 }
 332         }
 333
 334         block_info->already_processed = true;
 335         block_info->last_definition   = def;
 336 }
 337
 338 /**
 339  * @return Last definition of the given block.
 340  */
 341 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
 342                                         ir_node *block)
 343 {
 344         constr_info *block_info      = get_or_set_info(env, block);
 345         ir_node     *last_definition = block_info->last_definition;
 346
 347         if (last_definition != NULL)
 348                 return last_definition;
 349
 350         if (has_definition(block)) {
 351                 if (has_use(env, block)) {
 352                         if (!block_info->already_processed) {
 353                                 process_block(env, block);
 354                         }
 355                 }
 356                 else {
 357                         ir_node *def = NULL;
 358
 359                         /* Search the last definition of the block. */
 360                         sched_foreach_reverse(block, def) {
 361                                 if (is_definition(env, def)) {
 362                                         constr_info *info = get_info(env, def);
 363                                         def = info->definition;
 364                                         DBG((dbg, LEVEL_3, "\t...found definition %+F\n", def));
 365
 366                                         break;
 367                                 }
 368                         }
 369
 370                         assert(def && "No definition found");
 371
 372                         block_info->last_definition = def;
 373                 }
 374
 375                 return block_info->last_definition;
 376         } else if (Block_block_visited(block)) {
 377                 ir_node *phi = insert_dummy_phi(env, block);
 378
 379                 block_info->last_definition = phi;
 380
 381                 return phi;
 382         } else {
 383                 ir_node *def = get_def_at_idom(env, block);
 384
 385                 block_info->last_definition = def;
 386
 387                 return def;
 388         }
 389 }
 390
 391 /**
 392  * Fixes all operands of the given use.
 393  */
 394 static void search_def_at_block(be_ssa_construction_env_t *env, ir_node *use)
 395 {
 396         ir_node     *block      = get_nodes_block(use);
 397         constr_info *block_info = get_or_set_info(env, block);
 398
 399         if (block_info->already_processed)
 400                 return;
 401
 402         if (has_definition(block)) {
 403                 process_block(env, block);
 404         } else if (Block_block_visited(block)) {
 405                 ir_node *phi = insert_dummy_phi(env, block);
 406
 407                 set_operands(env, use, phi);
 408         } else {
 409                 ir_node *def = get_def_at_idom(env, block);
 410
 411                 set_operands(env, use, def);
 412         }
 413 }
 414
 415 void be_ssa_construction_init(be_ssa_construction_env_t *env, ir_graph *irg)
 416 {
 417         ir_node *sb   = get_irg_start_block(irg);
 418         int n_blocks  = get_Block_dom_max_subtree_pre_num(sb);
 419
 420         stat_ev_ctx_push_fobj("bessaconstr", irg);
 421         stat_ev_tim_push();
 422
 423         (void) n_blocks;
 424         stat_ev_dbl("bessaconstr_n_blocks", n_blocks);
 425
 426         memset(env, 0, sizeof(env[0]));
 427         be_assure_dom_front(irg);
 428
 429         env->irg       = irg;
 430         env->domfronts = be_get_irg_dom_front(irg);
 431         env->new_phis  = NEW_ARR_F(ir_node*, 0);
 432         env->worklist  = new_waitq();
 433         ir_nodemap_init(&env->infos, irg);
 434         obstack_init(&env->obst);
 435
 436         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED
 437                         | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
 438
 439         /* we use the visited flag to indicate blocks in the dominance frontier
 440          * and blocks that already have the relevant value at the end calculated */
 441         inc_irg_visited(irg);
 442         /* We use the block visited flag to indicate blocks in the dominance
 443          * frontier of some values (and this potentially needing phis) */
 444         inc_irg_block_visited(irg);
 445 }
 446
 447 void be_ssa_construction_destroy(be_ssa_construction_env_t *env)
 448 {
 449         stat_ev_int("bessaconstr_phis", ARR_LEN(env->new_phis));
 450         obstack_free(&env->obst, NULL);
 451         ir_nodemap_destroy(&env->infos);
 452         del_waitq(env->worklist);
 453         DEL_ARR_F(env->new_phis);
 454
 455         ir_free_resources(env->irg, IR_RESOURCE_IRN_VISITED
 456                         | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
 457
 458         stat_ev_tim_pop("bessaconstr_total_time");
 459         stat_ev_ctx_pop("bessaconstr");
 460 }
 461
 462 void be_ssa_construction_add_copy(be_ssa_construction_env_t *env,
 463                                   ir_node *copy)
 464 {
 465         ir_node *block;
 466
 467         assert(env->iterated_domfront_calculated == 0);
 468
 469         if (env->mode == NULL) {
 470                 env->mode    = get_irn_mode(copy);
 471                 env->phi_cls = arch_get_irn_reg_class(copy);
 472         } else {
 473                 assert(env->mode == get_irn_mode(copy));
 474         }
 475
 476         block = get_nodes_block(copy);
 477
 478         if (!has_definition(block)) {
 479                 waitq_put(env->worklist, block);
 480         }
 481         introduce_definition(env, copy);
 482 }
 483
 484 void be_ssa_construction_add_copies(be_ssa_construction_env_t *env,
 485                                     ir_node **copies, size_t copies_len)
 486 {
 487         size_t i;
 488
 489         assert(env->iterated_domfront_calculated == 0);
 490
 491         if (env->mode == NULL) {
 492                 env->mode    = get_irn_mode(copies[0]);
 493                 env->phi_cls = arch_get_irn_reg_class(copies[0]);
 494         }
 495
 496         for (i = 0; i < copies_len; ++i) {
 497                 ir_node *copy  = copies[i];
 498                 ir_node *block = get_nodes_block(copy);
 499
 500                 assert(env->mode == get_irn_mode(copy));
 501                 if (!has_definition(block)) {
 502                         waitq_put(env->worklist, block);
 503                 }
 504                 introduce_definition(env, copy);
 505         }
 506 }
 507
 508 void be_ssa_construction_set_ignore_uses(be_ssa_construction_env_t *env,
 509                                          const ir_nodeset_t *ignore_uses)
 510 {
 511         env->ignore_uses = ignore_uses;
 512 }
 513
 514 ir_node **be_ssa_construction_get_new_phis(be_ssa_construction_env_t *env)
 515 {
 516         return env->new_phis;
 517 }
 518
 519 /**
 520  * Fixes all arguments of a newly constructed phi.
 521  *
 522  * @see insert_dummy_phi
 523  */
 524 static void fix_phi_arguments(be_ssa_construction_env_t *env, ir_node *phi)
 525 {
 526         constr_info *info    = get_info(env, phi);
 527         ir_node     *block   = get_nodes_block(phi);
 528         int          i;
 529         int          n_preds = get_Block_n_cfgpreds(block);
 530
 531         DBG((dbg, LEVEL_3, "\tfixing phi arguments  %+F\n", phi));
 532
 533         for (i = 0; i < n_preds; ++i) {
 534                 ir_node *op = get_irn_n(phi, i);
 535
 536                 if (is_definition(env, op) || is_Dummy(op)) {
 537                         ir_node *pred_block = get_Block_cfgpred_block(block, i);
 538                         ir_node *pred_def   = search_def_end_of_block(env, pred_block);
 539
 540                         DBG((dbg, LEVEL_1, "\t...%+F(%d) -> %+F\n", phi, i, pred_def));
 541                         set_irn_n(phi, i, pred_def);
 542                 }
 543         }
 544
 545         info->already_processed = true;
 546 }
 547
 548 void be_ssa_construction_fix_users_array(be_ssa_construction_env_t *env,
 549                                          ir_node **nodes, size_t nodes_len)
 550 {
 551         size_t i;
 552         stat_ev_cnt_decl(uses);
 553
 554         be_timer_push(T_SSA_CONSTR);
 555
 556         if (!env->iterated_domfront_calculated) {
 557                 mark_iterated_dominance_frontiers(env);
 558                 env->iterated_domfront_calculated = 1;
 559         }
 560
 561         DBG((dbg, LEVEL_1, "\tfixing users array\n"));
 562
 563         assert(waitq_empty(env->worklist));
 564
 565         stat_ev_tim_push();
 566
 567         for (i = 0; i < nodes_len; ++i) {
 568                 const ir_edge_t *edge, *next;
 569                 ir_node *value = nodes[i];
 570                 DBG((dbg, LEVEL_3, "\tfixing users of %+F\n", value));
 571                 introduce_definition(env, value);
 572
 573                 foreach_out_edge_safe(value, edge, next) {
 574                         ir_node *use   = get_edge_src_irn(edge);
 575
 576                         if (env->ignore_uses != NULL &&
 577                                         ir_nodeset_contains(env->ignore_uses, use))
 578                                 continue;
 579
 580                         if (is_Anchor(use) || is_End(use))
 581                                 continue;
 582
 583                         introduce_use(env, use);
 584                 }
 585         }
 586
 587         assert(!waitq_empty(env->worklist));
 588
 589         while (!waitq_empty(env->worklist)) {
 590                 ir_node     *use  = (ir_node *)waitq_get(env->worklist);
 591                 constr_info *info = get_info(env, use);
 592
 593                 if (info->already_processed)
 594                         continue;
 595
 596                 if (is_Phi(use)) {
 597                         fix_phi_arguments(env, use);
 598                 }
 599                 else {
 600                         DBG((dbg, LEVEL_3, "\tsearching def for %+F at %+F\n", use, get_nodes_block(use)));
 601                         search_def_at_block(env, use);
 602                 }
 603
 604                 stat_ev_cnt_inc(uses);
 605         }
 606
 607         be_timer_pop(T_SSA_CONSTR);
 608
 609         stat_ev_tim_pop("bessaconstr_fix_time");
 610         stat_ev_cnt_done(uses, "bessaconstr_uses");
 611 }
 612
 613 void be_ssa_construction_fix_users(be_ssa_construction_env_t *env, ir_node *value)
 614 {
 615         be_ssa_construction_fix_users_array(env, &value, 1);
 616 }
 617
 618
 619 void be_ssa_construction_update_liveness_phis(be_ssa_construction_env_t *env,
 620                                               be_lv_t *lv)
 621 {
 622         int i, n;
 623
 624         be_timer_push(T_SSA_CONSTR);
 625
 626         n = ARR_LEN(env->new_phis);
 627         for (i = 0; i < n; ++i) {
 628                 ir_node *phi = env->new_phis[i];
 629                 be_liveness_introduce(lv, phi);
 630         }
 631
 632         be_timer_pop(T_SSA_CONSTR);
 633 }
 634
 635 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_ssaconstr)
 636 void be_init_ssaconstr(void)
 637 {
 638         FIRM_DBG_REGISTER(dbg, "firm.be.ssaconstr");
 639 }