nsz Git - libfirm/blob - ir/be/bessaconstr.c

   1 /*
   2  * This file is part of libFirm.
   3  * Copyright (C) 2012 University of Karlsruhe.
   4  */
   5
   6 /**
   7  * @file
   8  * @brief       SSA construction for a set of nodes
   9  * @author      Sebastian Hack, Daniel Grund, Matthias Braun, Christian Wuerdig,
  10  *              Sebastian Buchwald
  11  * @date        04.05.2005
  12  *
  13  * The problem: Given a value and a set of "copies" that are known to
  14  * represent the same abstract value, rewire all usages of the original value
  15  * to their closest copy while introducing phis as necessary.
  16  *
  17  * Algorithm: Mark all blocks in the iterated dominance frontiers of the value
  18  * and its copies. Link the copies ordered by dominance to the blocks.  Then
  19  * we search for each use all definitions in the current block, if none is
  20  * found, then we search one in the immediate dominator. If we are in a block
  21  * of the dominance frontier, create a phi and do the same search for all
  22  * phi arguments.
  23  *
  24  * A copy in this context means, that you want to introduce several new
  25  * abstract values (in Firm: nodes) for which you know, that they
  26  * represent the same concrete value. This is the case if you
  27  * - copy
  28  * - spill and reload
  29  * - re-materialize
  30  * a value.
  31  *
  32  * This function reroutes all uses of the original value to the copies in the
  33  * corresponding dominance subtrees and creates Phi functions where necessary.
  34  */
  35 #include "config.h"
  36
  37 /* statev in this file is extensive, so only enable if needed */
  38 #define DISABLE_STATEV
  39
  40 #include "bessaconstr.h"
  41 #include "bemodule.h"
  42 #include "besched.h"
  43 #include "beintlive_t.h"
  44 #include "beirg.h"
  45 #include "be_t.h"
  46 #include "benode.h"
  47
  48 #include "debug.h"
  49 #include "error.h"
  50 #include "pdeq.h"
  51 #include "array.h"
  52 #include "irdom.h"
  53 #include "irnodeset.h"
  54
  55 #include "ircons.h"
  56 #include "iredges_t.h"
  57 #include "statev_t.h"
  58
  59 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  60
  61 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
  62                                         ir_node *block);
  63
  64 struct constr_info {
  65         bool is_definition     : 1;
  66         bool is_use            : 1;
  67         bool already_processed : 1;
  68         union {
  69                 /* Since we only consider scheduled nodes,
  70                  * this points to the real definition (e.g. a Proj). */
  71                 ir_node *definition;
  72
  73                 /* Last definition of a block. */
  74                 ir_node *last_definition;
  75         } u;
  76 };
  77
  78 typedef struct constr_info constr_info;
  79
  80 /**
  81  * @return Whether the block contains a definition.
  82  */
  83 static bool has_definition(const ir_node *block)
  84 {
  85         return irn_visited(block);
  86 }
  87
  88 static constr_info *get_or_set_info(be_ssa_construction_env_t *env,
  89                                     const ir_node *node)
  90 {
  91         constr_info *info = ir_nodemap_get(constr_info, &env->infos, node);
  92         if (info == NULL) {
  93                 info = OALLOCZ(&env->obst, constr_info);
  94                 ir_nodemap_insert(&env->infos, node, info);
  95         }
  96         return info;
  97 }
  98
  99 static constr_info *get_info(const be_ssa_construction_env_t *env,
 100                              const ir_node *node)
 101 {
 102         return ir_nodemap_get(constr_info, &env->infos, node);
 103 }
 104
 105 /**
 106  * @return Whether the block contains a use.
 107  */
 108 static inline bool has_use(be_ssa_construction_env_t *env, ir_node *block)
 109 {
 110         constr_info *info = get_or_set_info(env, block);
 111         return info->is_use;
 112 }
 113
 114 /**
 115  * @return Whether the node is a definition.
 116  */
 117 static bool is_definition(be_ssa_construction_env_t *env, ir_node *node)
 118 {
 119         constr_info *info = get_info(env, node);
 120         return info != NULL && info->is_definition;
 121 }
 122
 123 /**
 124  * Introduces a definition at the corresponding block.
 125  */
 126 static void introduce_definition(be_ssa_construction_env_t *env, ir_node *def)
 127 {
 128         ir_node     *block      = get_nodes_block(def);
 129         constr_info *def_info   = get_or_set_info(env, def);
 130         ir_node     *skip       = skip_Proj(def);
 131         constr_info *skip_info  = get_or_set_info(env, skip);
 132         constr_info *block_info = get_or_set_info(env, block);
 133
 134         DBG((dbg, LEVEL_2, "\tintroducing definition %+F in %+F\n", def, block));
 135
 136         def_info->is_definition = true;
 137
 138         skip_info->is_definition = true;
 139         skip_info->u.definition  = def;
 140
 141         // Set the last definition if we only introduce one definition for the block
 142         if (has_definition(block)) {
 143                 assert(!block_info->already_processed);
 144                 block_info->u.last_definition = NULL;
 145         } else {
 146                 mark_irn_visited(block);
 147                 block_info->u.last_definition = def;
 148         }
 149 }
 150
 151 static void introduce_use(be_ssa_construction_env_t *env, ir_node *use)
 152 {
 153         ir_node     *block      = get_nodes_block(use);
 154         constr_info *info       = get_or_set_info(env, use);
 155         constr_info *block_info = get_or_set_info(env, block);
 156
 157         DBG((dbg, LEVEL_2, "\tintroducing use %+F in %+F\n", use, block));
 158
 159         info->is_use       = true;
 160         block_info->is_use = true;
 161
 162         waitq_put(env->worklist, use);
 163 }
 164
 165 /**
 166  * Calculates the iterated dominance frontier of a set of blocks. Marks the
 167  * blocks as visited. Sets the link fields of the blocks in the dominance
 168  * frontier to the block itself.
 169  */
 170 static void mark_iterated_dominance_frontiers(
 171                                            const be_ssa_construction_env_t *env)
 172 {
 173         stat_ev_cnt_decl(blocks);
 174         DBG((dbg, LEVEL_3, "Dominance Frontier:"));
 175         stat_ev_tim_push();
 176         while (!waitq_empty(env->worklist)) {
 177                 int i;
 178                 ir_node  *block    = (ir_node*)waitq_get(env->worklist);
 179                 ir_node **domfront = ir_get_dominance_frontier(block);
 180                 int domfront_len = ARR_LEN(domfront);
 181
 182                 for (i = 0; i < domfront_len; ++i) {
 183                         ir_node *y = domfront[i];
 184                         if (Block_block_visited(y))
 185                                 continue;
 186
 187                         if (!irn_visited(y)) {
 188                                 set_irn_link(y, NULL);
 189                                 waitq_put(env->worklist, y);
 190                         }
 191
 192                         DBG((dbg, LEVEL_3, " %+F", y));
 193                         mark_Block_block_visited(y);
 194                         stat_ev_cnt_inc(blocks);
 195                 }
 196         }
 197         stat_ev_tim_pop("bessaconstr_idf_time");
 198         stat_ev_cnt_done(blocks, "bessaconstr_idf_blocks");
 199         DBG((dbg, LEVEL_3, "\n"));
 200 }
 201
 202 /**
 203  * Inserts a new phi at the given block.
 204  *
 205  * The constructed phi has only Dummy operands,
 206  * but can be used as definition for other nodes.
 207  *
 208  * @see fix_phi_arguments
 209  */
 210 static ir_node *insert_dummy_phi(be_ssa_construction_env_t *env, ir_node *block)
 211 {
 212         int i, n_preds = get_Block_n_cfgpreds(block);
 213         ir_graph *irg = get_Block_irg(block);
 214         ir_node **ins = ALLOCAN(ir_node*, n_preds);
 215         ir_node  *dummy;
 216         ir_node  *phi;
 217
 218         DBG((dbg, LEVEL_3, "\t...create phi at block %+F\n", block));
 219
 220         assert(n_preds > 1);
 221
 222         dummy = new_r_Dummy(irg, env->mode);
 223         for (i = 0; i < n_preds; ++i) {
 224                 ins[i] = dummy;
 225         }
 226         phi = be_new_Phi(block, n_preds, ins, env->mode, env->phi_req);
 227         sched_add_after(block, phi);
 228         ARR_APP1(ir_node*, env->new_phis, phi);
 229
 230         DBG((dbg, LEVEL_2, "\tcreating phi %+F in %+F\n", phi, block));
 231         introduce_definition(env, phi);
 232
 233         waitq_put(env->worklist, phi);
 234
 235         return phi;
 236 }
 237
 238 /**
 239  * @return Last definition of the immediate dominator.
 240  */
 241 static ir_node *get_def_at_idom(be_ssa_construction_env_t *env, ir_node *block)
 242 {
 243         ir_node *dom = get_Block_idom(block);
 244         assert(dom != NULL);
 245         DBG((dbg, LEVEL_3, "\t...continue at idom %+F\n", dom));
 246         return search_def_end_of_block(env, dom);
 247 }
 248
 249 static ir_node *get_def_from_preds(be_ssa_construction_env_t *const env, ir_node *const block)
 250 {
 251         /* Create a phi if the block is in the dominance frontier. */
 252         if (Block_block_visited(block)) {
 253                 return insert_dummy_phi(env, block);
 254         } else {
 255                 return get_def_at_idom(env, block);
 256         }
 257 }
 258
 259 /**
 260  * Fixes all operands of a use.
 261  *
 262  * If an operand of the use is a (original) definition,
 263  * it will be replaced by the given definition.
 264  */
 265 static void set_operands(be_ssa_construction_env_t *env, ir_node *use, ir_node *def, constr_info *const use_info)
 266 {
 267         int arity = get_irn_arity(use);
 268         for (int i = 0; i < arity; ++i) {
 269                 ir_node *op = get_irn_n(use, i);
 270
 271                 if (is_definition(env, op)) {
 272                         DBG((dbg, LEVEL_1, "\t...%+F(%d) -> %+F\n", use, i, def));
 273                         set_irn_n(use, i, def);
 274                 }
 275         }
 276
 277         use_info->already_processed = true;
 278 }
 279
 280 /**
 281  * Fixes all uses of the given block.
 282  */
 283 static void process_block(be_ssa_construction_env_t *env, ir_node *block)
 284 {
 285         ir_node     *def        = NULL;
 286         constr_info *block_info = get_or_set_info(env, block);
 287
 288         assert(has_definition(block));
 289         assert(!block_info->already_processed && "Block already processed");
 290
 291         DBG((dbg, LEVEL_3, "\tprocessing block  %+F\n", block));
 292
 293         sched_foreach(block, node) {
 294                 constr_info *const info = get_info(env, node);
 295                 if (!info)
 296                         continue;
 297
 298                 if (info->is_use && !is_Phi(node)) {
 299                         DBG((dbg, LEVEL_3, "\t...found use %+F\n", node));
 300
 301                         if (def == NULL) {
 302                                 /* Create a phi if the block is in the dominance frontier. */
 303                                 def = get_def_from_preds(env, block);
 304                         }
 305
 306                         set_operands(env, node, def, info);
 307                 }
 308
 309                 if (info->is_definition) {
 310                         def = info->u.definition;
 311                         DBG((dbg, LEVEL_3, "\t...found definition %+F\n", def));
 312                 }
 313         }
 314
 315         block_info->already_processed = true;
 316         block_info->u.last_definition = def;
 317 }
 318
 319 /**
 320  * @return Last definition of the given block.
 321  */
 322 static ir_node *search_def_end_of_block(be_ssa_construction_env_t *env,
 323                                         ir_node *block)
 324 {
 325         constr_info *block_info      = get_or_set_info(env, block);
 326         ir_node     *last_definition = block_info->u.last_definition;
 327
 328         if (last_definition != NULL)
 329                 return last_definition;
 330
 331         if (has_definition(block)) {
 332                 if (has_use(env, block)) {
 333                         if (!block_info->already_processed) {
 334                                 process_block(env, block);
 335                         }
 336                 }
 337                 else {
 338                         /* Search the last definition of the block. */
 339                         sched_foreach_reverse(block, def) {
 340                                 constr_info const *const info = get_info(env, def);
 341                                 if (info && info->is_definition) {
 342                                         DBG((dbg, LEVEL_3, "\t...found definition %+F\n", info->u.definition));
 343                                         block_info->u.last_definition = info->u.definition;
 344                                         break;
 345                                 }
 346                         }
 347
 348                         assert(block_info->u.last_definition && "No definition found");
 349                 }
 350
 351                 return block_info->u.last_definition;
 352         } else {
 353                 ir_node *const def = get_def_from_preds(env, block);
 354                 block_info->u.last_definition = def;
 355                 return def;
 356         }
 357 }
 358
 359 /**
 360  * Fixes all operands of the given use.
 361  */
 362 static void search_def_at_block(be_ssa_construction_env_t *const env, ir_node *const use, constr_info *const info)
 363 {
 364         ir_node     *block      = get_nodes_block(use);
 365         constr_info *block_info = get_or_set_info(env, block);
 366
 367         if (block_info->already_processed)
 368                 return;
 369
 370         if (has_definition(block)) {
 371                 process_block(env, block);
 372         } else {
 373                 ir_node *const def = get_def_from_preds(env, block);
 374                 set_operands(env, use, def, info);
 375         }
 376 }
 377
 378 void be_ssa_construction_init(be_ssa_construction_env_t *env, ir_graph *irg)
 379 {
 380         stat_ev_ctx_push_fmt("bessaconstr", "%+F", irg);
 381         stat_ev_tim_push();
 382
 383         stat_ev_dbl("bessaconstr_n_blocks", get_Block_dom_max_subtree_pre_num(get_irg_start_block(irg)));
 384
 385         memset(env, 0, sizeof(env[0]));
 386
 387         env->irg       = irg;
 388         env->new_phis  = NEW_ARR_F(ir_node*, 0);
 389         env->worklist  = new_waitq();
 390         ir_nodemap_init(&env->infos, irg);
 391         obstack_init(&env->obst);
 392
 393         assure_irg_properties(env->irg,
 394                               IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE_FRONTIERS);
 395
 396         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED
 397                         | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
 398
 399         /* we use the visited flag to indicate blocks in the dominance frontier
 400          * and blocks that already have the relevant value at the end calculated */
 401         inc_irg_visited(irg);
 402         /* We use the block visited flag to indicate blocks in the dominance
 403          * frontier of some values (and this potentially needing phis) */
 404         inc_irg_block_visited(irg);
 405 }
 406
 407 void be_ssa_construction_destroy(be_ssa_construction_env_t *env)
 408 {
 409         stat_ev_int("bessaconstr_phis", ARR_LEN(env->new_phis));
 410         obstack_free(&env->obst, NULL);
 411         ir_nodemap_destroy(&env->infos);
 412         del_waitq(env->worklist);
 413         DEL_ARR_F(env->new_phis);
 414
 415         ir_free_resources(env->irg, IR_RESOURCE_IRN_VISITED
 416                         | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
 417
 418         stat_ev_tim_pop("bessaconstr_total_time");
 419         stat_ev_ctx_pop("bessaconstr");
 420 }
 421
 422 static void determine_phi_req(be_ssa_construction_env_t *env, ir_node *value)
 423 {
 424         const arch_register_req_t *req   = arch_get_irn_register_req(value);
 425         env->mode = get_irn_mode(value);
 426         if (req->width == 1) {
 427                 env->phi_req = req->cls->class_req;
 428         } else {
 429                 /* construct a new register req... */
 430                 ir_graph            *irg     = get_irn_irg(value);
 431                 struct obstack      *obst    = be_get_be_obst(irg);
 432                 arch_register_req_t *new_req = OALLOCZ(obst, arch_register_req_t);
 433                 new_req->cls   = req->cls;
 434                 new_req->type  = req->type & arch_register_req_type_aligned;
 435                 new_req->width = req->width;
 436                 env->phi_req = new_req;
 437         }
 438 }
 439
 440 void be_ssa_construction_add_copy(be_ssa_construction_env_t *env,
 441                                   ir_node *copy)
 442 {
 443         ir_node *block;
 444
 445         assert(env->iterated_domfront_calculated == 0);
 446
 447         if (env->mode == NULL) {
 448                 determine_phi_req(env, copy);
 449         } else {
 450                 assert(env->mode == get_irn_mode(copy));
 451         }
 452
 453         block = get_nodes_block(copy);
 454
 455         if (!has_definition(block)) {
 456                 waitq_put(env->worklist, block);
 457         }
 458         introduce_definition(env, copy);
 459 }
 460
 461 void be_ssa_construction_add_copies(be_ssa_construction_env_t *env,
 462                                     ir_node **copies, size_t copies_len)
 463 {
 464         size_t i;
 465
 466         assert(env->iterated_domfront_calculated == 0);
 467
 468         if (env->mode == NULL) {
 469                 determine_phi_req(env, copies[0]);
 470         }
 471
 472         for (i = 0; i < copies_len; ++i) {
 473                 ir_node *copy  = copies[i];
 474                 ir_node *block = get_nodes_block(copy);
 475
 476                 assert(env->mode == get_irn_mode(copy));
 477                 if (!has_definition(block)) {
 478                         waitq_put(env->worklist, block);
 479                 }
 480                 introduce_definition(env, copy);
 481         }
 482 }
 483
 484 ir_node **be_ssa_construction_get_new_phis(be_ssa_construction_env_t *env)
 485 {
 486         return env->new_phis;
 487 }
 488
 489 /**
 490  * Fixes all arguments of a newly constructed phi.
 491  *
 492  * @see insert_dummy_phi
 493  */
 494 static void fix_phi_arguments(be_ssa_construction_env_t *const env, ir_node *const phi, constr_info *const info)
 495 {
 496         ir_node *block   = get_nodes_block(phi);
 497         int      n_preds = get_Block_n_cfgpreds(block);
 498
 499         DBG((dbg, LEVEL_3, "\tfixing phi arguments  %+F\n", phi));
 500
 501         for (int i = 0; i < n_preds; ++i) {
 502                 ir_node *op = get_irn_n(phi, i);
 503
 504                 if (is_definition(env, op) || is_Dummy(op)) {
 505                         ir_node *pred_block = get_Block_cfgpred_block(block, i);
 506                         ir_node *pred_def   = search_def_end_of_block(env, pred_block);
 507
 508                         DBG((dbg, LEVEL_1, "\t...%+F(%d) -> %+F\n", phi, i, pred_def));
 509                         set_irn_n(phi, i, pred_def);
 510                 }
 511         }
 512
 513         info->already_processed = true;
 514 }
 515
 516 void be_ssa_construction_fix_users_array(be_ssa_construction_env_t *env,
 517                                          ir_node **nodes, size_t nodes_len)
 518 {
 519         size_t i;
 520         stat_ev_cnt_decl(uses);
 521
 522         be_timer_push(T_SSA_CONSTR);
 523
 524         if (!env->iterated_domfront_calculated) {
 525                 mark_iterated_dominance_frontiers(env);
 526                 env->iterated_domfront_calculated = 1;
 527         }
 528
 529         DBG((dbg, LEVEL_1, "\tfixing users array\n"));
 530
 531         assert(waitq_empty(env->worklist));
 532
 533         stat_ev_tim_push();
 534
 535         for (i = 0; i < nodes_len; ++i) {
 536                 ir_node *value = nodes[i];
 537                 DBG((dbg, LEVEL_3, "\tfixing users of %+F\n", value));
 538                 introduce_definition(env, value);
 539
 540                 foreach_out_edge_safe(value, edge) {
 541                         ir_node *const use = get_edge_src_irn(edge);
 542                         if (is_Anchor(use) || is_End(use))
 543                                 continue;
 544
 545                         introduce_use(env, use);
 546                 }
 547         }
 548
 549         assert(!waitq_empty(env->worklist));
 550
 551         while (!waitq_empty(env->worklist)) {
 552                 ir_node     *use  = (ir_node *)waitq_get(env->worklist);
 553                 constr_info *info = get_info(env, use);
 554
 555                 if (info->already_processed)
 556                         continue;
 557
 558                 if (is_Phi(use)) {
 559                         fix_phi_arguments(env, use, info);
 560                 }
 561                 else {
 562                         DBG((dbg, LEVEL_3, "\tsearching def for %+F at %+F\n", use, get_nodes_block(use)));
 563                         search_def_at_block(env, use, info);
 564                 }
 565
 566                 stat_ev_cnt_inc(uses);
 567         }
 568
 569         be_timer_pop(T_SSA_CONSTR);
 570
 571         stat_ev_tim_pop("bessaconstr_fix_time");
 572         stat_ev_cnt_done(uses, "bessaconstr_uses");
 573 }
 574
 575 void be_ssa_construction_fix_users(be_ssa_construction_env_t *env, ir_node *value)
 576 {
 577         be_ssa_construction_fix_users_array(env, &value, 1);
 578 }
 579
 580
 581 void be_ssa_construction_update_liveness_phis(be_ssa_construction_env_t *env,
 582                                               be_lv_t *lv)
 583 {
 584         int i, n;
 585
 586         be_timer_push(T_SSA_CONSTR);
 587
 588         n = ARR_LEN(env->new_phis);
 589         for (i = 0; i < n; ++i) {
 590                 ir_node *phi = env->new_phis[i];
 591                 be_liveness_introduce(lv, phi);
 592         }
 593
 594         be_timer_pop(T_SSA_CONSTR);
 595 }
 596
 597 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_ssaconstr)
 598 void be_init_ssaconstr(void)
 599 {
 600         FIRM_DBG_REGISTER(dbg, "firm.be.ssaconstr");
 601 }