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