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
  72 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  73
  74 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
  75                                         ir_node *block);
  76
  77 struct constr_info {
  78         bool is_definition     : 1;
  79         bool is_use            : 1;
  80         bool already_processed : 1;
  81         union {
  82                 /* Since we only consider scheduled nodes,
  83                  * this points to the real definition (e.g. a Proj). */
  84                 ir_node *definition;
  85
  86                 /* Last definition of a block. */
  87                 ir_node *last_definition;
  88         } u;
  89 };
  90
  91 typedef struct constr_info constr_info;
  92
  93 /**
  94  * @return Whether the block contains a definition.
  95  */
  96 static bool has_definition(const ir_node *block)
  97 {
  98         return irn_visited(block);
  99 }
 100
 101 static constr_info *get_or_set_info(be_ssa_construction_env_t *env,
 102                                     const ir_node *node)
 103 {
 104         constr_info *info = (constr_info*)ir_nodemap_get(&env->infos, node);
 105         if (info == NULL) {
 106                 info = OALLOCZ(&env->obst, constr_info);
 107                 ir_nodemap_insert(&env->infos, node, info);
 108         }
 109         return info;
 110 }
 111
 112 static constr_info *get_info(const be_ssa_construction_env_t *env,
 113                              const ir_node *node)
 114 {
 115         return (constr_info*)ir_nodemap_get(&env->infos, node);
 116 }
 117
 118 /**
 119  * @return Whether the block contains a use.
 120  */
 121 static inline bool has_use(be_ssa_construction_env_t *env, ir_node *block)
 122 {
 123         constr_info *info = get_or_set_info(env, block);
 124         return info->is_use;
 125 }
 126
 127 /**
 128  * @return Whether the node is a definition.
 129  */
 130 static bool is_definition(be_ssa_construction_env_t *env, ir_node *node)
 131 {
 132         constr_info *info = get_info(env, node);
 133         return info != NULL && info->is_definition;
 134 }
 135
 136 /**
 137  * @return Whether the node is a use.
 138  */
 139 static bool is_use(const be_ssa_construction_env_t *env, ir_node *node)
 140 {
 141         constr_info *info = get_info(env, node);
 142         return info != NULL && info->is_use;
 143 }
 144
 145 /**
 146  * Introduces a definition at the corresponding block.
 147  */
 148 static void introduce_definition(be_ssa_construction_env_t *env, ir_node *def)
 149 {
 150         ir_node     *block      = get_nodes_block(def);
 151         constr_info *def_info   = get_or_set_info(env, def);
 152         ir_node     *skip       = skip_Proj(def);
 153         constr_info *skip_info  = get_or_set_info(env, skip);
 154         constr_info *block_info = get_or_set_info(env, block);
 155
 156         DBG((dbg, LEVEL_2, "\tintroducing definition %+F in %+F\n", def, block));
 157
 158         def_info->is_definition = true;
 159
 160         skip_info->is_definition = true;
 161         skip_info->u.definition  = def;
 162
 163         // Set the last definition if we only introduce one definition for the block
 164         if (has_definition(block)) {
 165                 assert(!block_info->already_processed);
 166                 block_info->u.last_definition = NULL;
 167         } else {
 168                 mark_irn_visited(block);
 169                 block_info->u.last_definition = def;
 170         }
 171 }
 172
 173 static void introduce_use(be_ssa_construction_env_t *env, ir_node *use)
 174 {
 175         ir_node     *block      = get_nodes_block(use);
 176         constr_info *info       = get_or_set_info(env, use);
 177         constr_info *block_info = get_or_set_info(env, block);
 178
 179         DBG((dbg, LEVEL_2, "\tintroducing use %+F in %+F\n", use, block));
 180
 181         info->is_use       = true;
 182         block_info->is_use = true;
 183
 184         waitq_put(env->worklist, use);
 185 }
 186
 187 /**
 188  * Calculates the iterated dominance frontier of a set of blocks. Marks the
 189  * blocks as visited. Sets the link fields of the blocks in the dominance
 190  * frontier to the block itself.
 191  */
 192 static void mark_iterated_dominance_frontiers(
 193                                            const be_ssa_construction_env_t *env)
 194 {
 195         stat_ev_cnt_decl(blocks);
 196         DBG((dbg, LEVEL_3, "Dominance Frontier:"));
 197         stat_ev_tim_push();
 198         while (!waitq_empty(env->worklist)) {
 199                 int i;
 200                 ir_node  *block    = (ir_node*)waitq_get(env->worklist);
 201                 ir_node **domfront = ir_get_dominance_frontier(block);
 202                 int domfront_len = ARR_LEN(domfront);
 203
 204                 for (i = 0; i < domfront_len; ++i) {
 205                         ir_node *y = domfront[i];
 206                         if (Block_block_visited(y))
 207                                 continue;
 208
 209                         if (!irn_visited(y)) {
 210                                 set_irn_link(y, NULL);
 211                                 waitq_put(env->worklist, y);
 212                         }
 213
 214                         DBG((dbg, LEVEL_3, " %+F", y));
 215                         mark_Block_block_visited(y);
 216                         stat_ev_cnt_inc(blocks);
 217                 }
 218         }
 219         stat_ev_tim_pop("bessaconstr_idf_time");
 220         stat_ev_cnt_done(blocks, "bessaconstr_idf_blocks");
 221         DBG((dbg, LEVEL_3, "\n"));
 222 }
 223
 224 /**
 225  * Inserts a new phi at the given block.
 226  *
 227  * The constructed phi has only Dummy operands,
 228  * but can be used as definition for other nodes.
 229  *
 230  * @see fix_phi_arguments
 231  */
 232 static ir_node *insert_dummy_phi(be_ssa_construction_env_t *env, ir_node *block)
 233 {
 234         int i, n_preds = get_Block_n_cfgpreds(block);
 235         ir_graph *irg = get_Block_irg(block);
 236         ir_node **ins = ALLOCAN(ir_node*, n_preds);
 237         ir_node  *dummy;
 238         ir_node  *phi;
 239
 240         DBG((dbg, LEVEL_3, "\t...create phi at block %+F\n", block));
 241
 242         assert(n_preds > 1);
 243
 244         dummy = new_r_Dummy(irg, env->mode);
 245         for (i = 0; i < n_preds; ++i) {
 246                 ins[i] = dummy;
 247         }
 248         phi = be_new_Phi(block, n_preds, ins, env->mode, env->phi_req);
 249         sched_add_after(block, phi);
 250         ARR_APP1(ir_node*, env->new_phis, phi);
 251
 252         DBG((dbg, LEVEL_2, "\tcreating phi %+F in %+F\n", phi, block));
 253         introduce_definition(env, phi);
 254
 255         waitq_put(env->worklist, phi);
 256
 257         return phi;
 258 }
 259
 260 /**
 261  * @return Last definition of the immediate dominator.
 262  */
 263 static ir_node *get_def_at_idom(be_ssa_construction_env_t *env, ir_node *block)
 264 {
 265         ir_node *dom = get_Block_idom(block);
 266         assert(dom != NULL);
 267         DBG((dbg, LEVEL_3, "\t...continue at idom %+F\n", dom));
 268         return search_def_end_of_block(env, dom);
 269 }
 270
 271 /**
 272  * Fixes all operands of a use.
 273  *
 274  * If an operand of the use is a (original) definition,
 275  * it will be replaced by the given definition.
 276  */
 277 static void set_operands(be_ssa_construction_env_t *env, ir_node *use, ir_node *def)
 278 {
 279         constr_info *info  = get_info(env, use);
 280         int          arity = get_irn_arity(use);
 281         int          i;
 282
 283         for (i = 0; i < arity; ++i) {
 284                 ir_node *op = get_irn_n(use, i);
 285
 286                 if (is_definition(env, op)) {
 287                         DBG((dbg, LEVEL_1, "\t...%+F(%d) -> %+F\n", use, i, def));
 288                         set_irn_n(use, i, def);
 289                 }
 290         }
 291
 292         info->already_processed = true;
 293 }
 294
 295 /**
 296  * Fixes all uses of the given block.
 297  */
 298 static void process_block(be_ssa_construction_env_t *env, ir_node *block)
 299 {
 300         ir_node     *node;
 301         ir_node     *def        = NULL;
 302         constr_info *block_info = get_or_set_info(env, block);
 303
 304         assert(has_definition(block));
 305         assert(!block_info->already_processed && "Block already processed");
 306
 307         DBG((dbg, LEVEL_3, "\tprocessing block  %+F\n", block));
 308
 309         sched_foreach(block, node) {
 310                 if (is_use(env, node) && !is_Phi(node)) {
 311                         DBG((dbg, LEVEL_3, "\t...found use %+F\n", node));
 312
 313                         if (def == NULL) {
 314                                 /* Create a phi if the block is in the dominance frontier. */
 315                                 if (Block_block_visited(block)) {
 316                                         def = insert_dummy_phi(env, block);
 317                                 }
 318                                 else {
 319                                         def = get_def_at_idom(env, block);
 320                                 }
 321                         }
 322
 323                         set_operands(env, node, def);
 324                 }
 325
 326                 if (is_definition(env, node)) {
 327                         constr_info *info = get_info(env, node);
 328                         def = info->u.definition;
 329                         DBG((dbg, LEVEL_3, "\t...found definition %+F\n", def));
 330                 }
 331         }
 332
 333         block_info->already_processed = true;
 334         block_info->u.last_definition = def;
 335 }
 336
 337 /**
 338  * @return Last definition of the given block.
 339  */
 340 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
 341                                         ir_node *block)
 342 {
 343         constr_info *block_info      = get_or_set_info(env, block);
 344         ir_node     *last_definition = block_info->u.last_definition;
 345
 346         if (last_definition != NULL)
 347                 return last_definition;
 348
 349         if (has_definition(block)) {
 350                 if (has_use(env, block)) {
 351                         if (!block_info->already_processed) {
 352                                 process_block(env, block);
 353                         }
 354                 }
 355                 else {
 356                         ir_node *def = NULL;
 357
 358                         /* Search the last definition of the block. */
 359                         sched_foreach_reverse(block, def) {
 360                                 if (is_definition(env, def)) {
 361                                         constr_info *info = get_info(env, def);
 362                                         def = info->u.definition;
 363                                         DBG((dbg, LEVEL_3, "\t...found definition %+F\n", def));
 364
 365                                         break;
 366                                 }
 367                         }
 368
 369                         assert(def && "No definition found");
 370
 371                         block_info->u.last_definition = def;
 372                 }
 373
 374                 return block_info->u.last_definition;
 375         } else if (Block_block_visited(block)) {
 376                 ir_node *phi = insert_dummy_phi(env, block);
 377
 378                 block_info->u.last_definition = phi;
 379
 380                 return phi;
 381         } else {
 382                 ir_node *def = get_def_at_idom(env, block);
 383
 384                 block_info->u.last_definition = def;
 385
 386                 return def;
 387         }
 388 }
 389
 390 /**
 391  * Fixes all operands of the given use.
 392  */
 393 static void search_def_at_block(be_ssa_construction_env_t *env, ir_node *use)
 394 {
 395         ir_node     *block      = get_nodes_block(use);
 396         constr_info *block_info = get_or_set_info(env, block);
 397
 398         if (block_info->already_processed)
 399                 return;
 400
 401         if (has_definition(block)) {
 402                 process_block(env, block);
 403         } else if (Block_block_visited(block)) {
 404                 ir_node *phi = insert_dummy_phi(env, block);
 405
 406                 set_operands(env, use, phi);
 407         } else {
 408                 ir_node *def = get_def_at_idom(env, block);
 409
 410                 set_operands(env, use, def);
 411         }
 412 }
 413
 414 void be_ssa_construction_init(be_ssa_construction_env_t *env, ir_graph *irg)
 415 {
 416         ir_node *sb   = get_irg_start_block(irg);
 417         int n_blocks  = get_Block_dom_max_subtree_pre_num(sb);
 418
 419         stat_ev_ctx_push_fobj("bessaconstr", irg);
 420         stat_ev_tim_push();
 421
 422         (void) n_blocks;
 423         stat_ev_dbl("bessaconstr_n_blocks", n_blocks);
 424
 425         memset(env, 0, sizeof(env[0]));
 426
 427         env->irg       = irg;
 428         env->new_phis  = NEW_ARR_F(ir_node*, 0);
 429         env->worklist  = new_waitq();
 430         ir_nodemap_init(&env->infos, irg);
 431         obstack_init(&env->obst);
 432
 433         assure_irg_properties(env->irg,
 434                               IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE_FRONTIERS);
 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 static void determine_phi_req(be_ssa_construction_env_t *env, ir_node *value)
 463 {
 464         const arch_register_req_t *req   = arch_get_irn_register_req(value);
 465         env->mode = get_irn_mode(value);
 466         if (req->width == 1) {
 467                 env->phi_req = req->cls->class_req;
 468         } else {
 469                 /* construct a new register req... */
 470                 ir_graph            *irg     = get_irn_irg(value);
 471                 struct obstack      *obst    = be_get_be_obst(irg);
 472                 arch_register_req_t *new_req = OALLOCZ(obst, arch_register_req_t);
 473                 new_req->cls   = req->cls;
 474                 new_req->type  = req->type & arch_register_req_type_aligned;
 475                 new_req->width = req->width;
 476                 env->phi_req = new_req;
 477         }
 478 }
 479
 480 void be_ssa_construction_add_copy(be_ssa_construction_env_t *env,
 481                                   ir_node *copy)
 482 {
 483         ir_node *block;
 484
 485         assert(env->iterated_domfront_calculated == 0);
 486
 487         if (env->mode == NULL) {
 488                 determine_phi_req(env, copy);
 489         } else {
 490                 assert(env->mode == get_irn_mode(copy));
 491         }
 492
 493         block = get_nodes_block(copy);
 494
 495         if (!has_definition(block)) {
 496                 waitq_put(env->worklist, block);
 497         }
 498         introduce_definition(env, copy);
 499 }
 500
 501 void be_ssa_construction_add_copies(be_ssa_construction_env_t *env,
 502                                     ir_node **copies, size_t copies_len)
 503 {
 504         size_t i;
 505
 506         assert(env->iterated_domfront_calculated == 0);
 507
 508         if (env->mode == NULL) {
 509                 determine_phi_req(env, copies[0]);
 510         }
 511
 512         for (i = 0; i < copies_len; ++i) {
 513                 ir_node *copy  = copies[i];
 514                 ir_node *block = get_nodes_block(copy);
 515
 516                 assert(env->mode == get_irn_mode(copy));
 517                 if (!has_definition(block)) {
 518                         waitq_put(env->worklist, block);
 519                 }
 520                 introduce_definition(env, copy);
 521         }
 522 }
 523
 524 void be_ssa_construction_set_ignore_uses(be_ssa_construction_env_t *env,
 525                                          const ir_nodeset_t *ignore_uses)
 526 {
 527         env->ignore_uses = ignore_uses;
 528 }
 529
 530 ir_node **be_ssa_construction_get_new_phis(be_ssa_construction_env_t *env)
 531 {
 532         return env->new_phis;
 533 }
 534
 535 /**
 536  * Fixes all arguments of a newly constructed phi.
 537  *
 538  * @see insert_dummy_phi
 539  */
 540 static void fix_phi_arguments(be_ssa_construction_env_t *env, ir_node *phi)
 541 {
 542         constr_info *info    = get_info(env, phi);
 543         ir_node     *block   = get_nodes_block(phi);
 544         int          i;
 545         int          n_preds = get_Block_n_cfgpreds(block);
 546
 547         DBG((dbg, LEVEL_3, "\tfixing phi arguments  %+F\n", phi));
 548
 549         for (i = 0; i < n_preds; ++i) {
 550                 ir_node *op = get_irn_n(phi, i);
 551
 552                 if (is_definition(env, op) || is_Dummy(op)) {
 553                         ir_node *pred_block = get_Block_cfgpred_block(block, i);
 554                         ir_node *pred_def   = search_def_end_of_block(env, pred_block);
 555
 556                         DBG((dbg, LEVEL_1, "\t...%+F(%d) -> %+F\n", phi, i, pred_def));
 557                         set_irn_n(phi, i, pred_def);
 558                 }
 559         }
 560
 561         info->already_processed = true;
 562 }
 563
 564 void be_ssa_construction_fix_users_array(be_ssa_construction_env_t *env,
 565                                          ir_node **nodes, size_t nodes_len)
 566 {
 567         size_t i;
 568         stat_ev_cnt_decl(uses);
 569
 570         be_timer_push(T_SSA_CONSTR);
 571
 572         if (!env->iterated_domfront_calculated) {
 573                 mark_iterated_dominance_frontiers(env);
 574                 env->iterated_domfront_calculated = 1;
 575         }
 576
 577         DBG((dbg, LEVEL_1, "\tfixing users array\n"));
 578
 579         assert(waitq_empty(env->worklist));
 580
 581         stat_ev_tim_push();
 582
 583         for (i = 0; i < nodes_len; ++i) {
 584                 const ir_edge_t *edge, *next;
 585                 ir_node *value = nodes[i];
 586                 DBG((dbg, LEVEL_3, "\tfixing users of %+F\n", value));
 587                 introduce_definition(env, value);
 588
 589                 foreach_out_edge_safe(value, edge, next) {
 590                         ir_node *use   = get_edge_src_irn(edge);
 591
 592                         if (env->ignore_uses != NULL &&
 593                                         ir_nodeset_contains(env->ignore_uses, use))
 594                                 continue;
 595
 596                         if (is_Anchor(use) || is_End(use))
 597                                 continue;
 598
 599                         introduce_use(env, use);
 600                 }
 601         }
 602
 603         assert(!waitq_empty(env->worklist));
 604
 605         while (!waitq_empty(env->worklist)) {
 606                 ir_node     *use  = (ir_node *)waitq_get(env->worklist);
 607                 constr_info *info = get_info(env, use);
 608
 609                 if (info->already_processed)
 610                         continue;
 611
 612                 if (is_Phi(use)) {
 613                         fix_phi_arguments(env, use);
 614                 }
 615                 else {
 616                         DBG((dbg, LEVEL_3, "\tsearching def for %+F at %+F\n", use, get_nodes_block(use)));
 617                         search_def_at_block(env, use);
 618                 }
 619
 620                 stat_ev_cnt_inc(uses);
 621         }
 622
 623         be_timer_pop(T_SSA_CONSTR);
 624
 625         stat_ev_tim_pop("bessaconstr_fix_time");
 626         stat_ev_cnt_done(uses, "bessaconstr_uses");
 627 }
 628
 629 void be_ssa_construction_fix_users(be_ssa_construction_env_t *env, ir_node *value)
 630 {
 631         be_ssa_construction_fix_users_array(env, &value, 1);
 632 }
 633
 634
 635 void be_ssa_construction_update_liveness_phis(be_ssa_construction_env_t *env,
 636                                               be_lv_t *lv)
 637 {
 638         int i, n;
 639
 640         be_timer_push(T_SSA_CONSTR);
 641
 642         n = ARR_LEN(env->new_phis);
 643         for (i = 0; i < n; ++i) {
 644                 ir_node *phi = env->new_phis[i];
 645                 be_liveness_introduce(lv, phi);
 646         }
 647
 648         be_timer_pop(T_SSA_CONSTR);
 649 }
 650
 651 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_ssaconstr)
 652 void be_init_ssaconstr(void)
 653 {
 654         FIRM_DBG_REGISTER(dbg, "firm.be.ssaconstr");
 655 }