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  * @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->u.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->u.last_definition = NULL;
 168         } else {
 169                 mark_irn_visited(block);
 170                 block_info->u.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 = ir_get_dominance_frontier(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_req);
 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     *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                         /* Search the last definition of the block. */
 357                         sched_foreach_reverse(block, def) {
 358                                 if (is_definition(env, def)) {
 359                                         constr_info *info = get_info(env, def);
 360                                         DBG((dbg, LEVEL_3, "\t...found definition %+F\n", info->u.definition));
 361                                         block_info->u.last_definition = info->u.definition;
 362                                         break;
 363                                 }
 364                         }
 365
 366                         assert(block_info->u.last_definition && "No definition found");
 367                 }
 368
 369                 return block_info->u.last_definition;
 370         } else if (Block_block_visited(block)) {
 371                 ir_node *phi = insert_dummy_phi(env, block);
 372
 373                 block_info->u.last_definition = phi;
 374
 375                 return phi;
 376         } else {
 377                 ir_node *def = get_def_at_idom(env, block);
 378
 379                 block_info->u.last_definition = def;
 380
 381                 return def;
 382         }
 383 }
 384
 385 /**
 386  * Fixes all operands of the given use.
 387  */
 388 static void search_def_at_block(be_ssa_construction_env_t *env, ir_node *use)
 389 {
 390         ir_node     *block      = get_nodes_block(use);
 391         constr_info *block_info = get_or_set_info(env, block);
 392
 393         if (block_info->already_processed)
 394                 return;
 395
 396         if (has_definition(block)) {
 397                 process_block(env, block);
 398         } else if (Block_block_visited(block)) {
 399                 ir_node *phi = insert_dummy_phi(env, block);
 400
 401                 set_operands(env, use, phi);
 402         } else {
 403                 ir_node *def = get_def_at_idom(env, block);
 404
 405                 set_operands(env, use, def);
 406         }
 407 }
 408
 409 void be_ssa_construction_init(be_ssa_construction_env_t *env, ir_graph *irg)
 410 {
 411         ir_node *sb   = get_irg_start_block(irg);
 412         int n_blocks  = get_Block_dom_max_subtree_pre_num(sb);
 413
 414         stat_ev_ctx_push_fmt("bessaconstr", "%+F", irg);
 415         stat_ev_tim_push();
 416
 417         (void) n_blocks;
 418         stat_ev_dbl("bessaconstr_n_blocks", n_blocks);
 419
 420         memset(env, 0, sizeof(env[0]));
 421
 422         env->irg       = irg;
 423         env->new_phis  = NEW_ARR_F(ir_node*, 0);
 424         env->worklist  = new_waitq();
 425         ir_nodemap_init(&env->infos, irg);
 426         obstack_init(&env->obst);
 427
 428         assure_irg_properties(env->irg,
 429                               IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE_FRONTIERS);
 430
 431         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED
 432                         | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
 433
 434         /* we use the visited flag to indicate blocks in the dominance frontier
 435          * and blocks that already have the relevant value at the end calculated */
 436         inc_irg_visited(irg);
 437         /* We use the block visited flag to indicate blocks in the dominance
 438          * frontier of some values (and this potentially needing phis) */
 439         inc_irg_block_visited(irg);
 440 }
 441
 442 void be_ssa_construction_destroy(be_ssa_construction_env_t *env)
 443 {
 444         stat_ev_int("bessaconstr_phis", ARR_LEN(env->new_phis));
 445         obstack_free(&env->obst, NULL);
 446         ir_nodemap_destroy(&env->infos);
 447         del_waitq(env->worklist);
 448         DEL_ARR_F(env->new_phis);
 449
 450         ir_free_resources(env->irg, IR_RESOURCE_IRN_VISITED
 451                         | IR_RESOURCE_BLOCK_VISITED | IR_RESOURCE_IRN_LINK);
 452
 453         stat_ev_tim_pop("bessaconstr_total_time");
 454         stat_ev_ctx_pop("bessaconstr");
 455 }
 456
 457 static void determine_phi_req(be_ssa_construction_env_t *env, ir_node *value)
 458 {
 459         const arch_register_req_t *req   = arch_get_irn_register_req(value);
 460         env->mode = get_irn_mode(value);
 461         if (req->width == 1) {
 462                 env->phi_req = req->cls->class_req;
 463         } else {
 464                 /* construct a new register req... */
 465                 ir_graph            *irg     = get_irn_irg(value);
 466                 struct obstack      *obst    = be_get_be_obst(irg);
 467                 arch_register_req_t *new_req = OALLOCZ(obst, arch_register_req_t);
 468                 new_req->cls   = req->cls;
 469                 new_req->type  = req->type & arch_register_req_type_aligned;
 470                 new_req->width = req->width;
 471                 env->phi_req = new_req;
 472         }
 473 }
 474
 475 void be_ssa_construction_add_copy(be_ssa_construction_env_t *env,
 476                                   ir_node *copy)
 477 {
 478         ir_node *block;
 479
 480         assert(env->iterated_domfront_calculated == 0);
 481
 482         if (env->mode == NULL) {
 483                 determine_phi_req(env, copy);
 484         } else {
 485                 assert(env->mode == get_irn_mode(copy));
 486         }
 487
 488         block = get_nodes_block(copy);
 489
 490         if (!has_definition(block)) {
 491                 waitq_put(env->worklist, block);
 492         }
 493         introduce_definition(env, copy);
 494 }
 495
 496 void be_ssa_construction_add_copies(be_ssa_construction_env_t *env,
 497                                     ir_node **copies, size_t copies_len)
 498 {
 499         size_t i;
 500
 501         assert(env->iterated_domfront_calculated == 0);
 502
 503         if (env->mode == NULL) {
 504                 determine_phi_req(env, copies[0]);
 505         }
 506
 507         for (i = 0; i < copies_len; ++i) {
 508                 ir_node *copy  = copies[i];
 509                 ir_node *block = get_nodes_block(copy);
 510
 511                 assert(env->mode == get_irn_mode(copy));
 512                 if (!has_definition(block)) {
 513                         waitq_put(env->worklist, block);
 514                 }
 515                 introduce_definition(env, copy);
 516         }
 517 }
 518
 519 void be_ssa_construction_set_ignore_uses(be_ssa_construction_env_t *env,
 520                                          const ir_nodeset_t *ignore_uses)
 521 {
 522         env->ignore_uses = ignore_uses;
 523 }
 524
 525 ir_node **be_ssa_construction_get_new_phis(be_ssa_construction_env_t *env)
 526 {
 527         return env->new_phis;
 528 }
 529
 530 /**
 531  * Fixes all arguments of a newly constructed phi.
 532  *
 533  * @see insert_dummy_phi
 534  */
 535 static void fix_phi_arguments(be_ssa_construction_env_t *env, ir_node *phi)
 536 {
 537         constr_info *info    = get_info(env, phi);
 538         ir_node     *block   = get_nodes_block(phi);
 539         int          i;
 540         int          n_preds = get_Block_n_cfgpreds(block);
 541
 542         DBG((dbg, LEVEL_3, "\tfixing phi arguments  %+F\n", phi));
 543
 544         for (i = 0; i < n_preds; ++i) {
 545                 ir_node *op = get_irn_n(phi, i);
 546
 547                 if (is_definition(env, op) || is_Dummy(op)) {
 548                         ir_node *pred_block = get_Block_cfgpred_block(block, i);
 549                         ir_node *pred_def   = search_def_end_of_block(env, pred_block);
 550
 551                         DBG((dbg, LEVEL_1, "\t...%+F(%d) -> %+F\n", phi, i, pred_def));
 552                         set_irn_n(phi, i, pred_def);
 553                 }
 554         }
 555
 556         info->already_processed = true;
 557 }
 558
 559 void be_ssa_construction_fix_users_array(be_ssa_construction_env_t *env,
 560                                          ir_node **nodes, size_t nodes_len)
 561 {
 562         size_t i;
 563         stat_ev_cnt_decl(uses);
 564
 565         be_timer_push(T_SSA_CONSTR);
 566
 567         if (!env->iterated_domfront_calculated) {
 568                 mark_iterated_dominance_frontiers(env);
 569                 env->iterated_domfront_calculated = 1;
 570         }
 571
 572         DBG((dbg, LEVEL_1, "\tfixing users array\n"));
 573
 574         assert(waitq_empty(env->worklist));
 575
 576         stat_ev_tim_push();
 577
 578         for (i = 0; i < nodes_len; ++i) {
 579                 ir_node *value = nodes[i];
 580                 DBG((dbg, LEVEL_3, "\tfixing users of %+F\n", value));
 581                 introduce_definition(env, value);
 582
 583                 foreach_out_edge_safe(value, edge) {
 584                         ir_node *use   = get_edge_src_irn(edge);
 585
 586                         if (env->ignore_uses != NULL &&
 587                                         ir_nodeset_contains(env->ignore_uses, use))
 588                                 continue;
 589
 590                         if (is_Anchor(use) || is_End(use))
 591                                 continue;
 592
 593                         introduce_use(env, use);
 594                 }
 595         }
 596
 597         assert(!waitq_empty(env->worklist));
 598
 599         while (!waitq_empty(env->worklist)) {
 600                 ir_node     *use  = (ir_node *)waitq_get(env->worklist);
 601                 constr_info *info = get_info(env, use);
 602
 603                 if (info->already_processed)
 604                         continue;
 605
 606                 if (is_Phi(use)) {
 607                         fix_phi_arguments(env, use);
 608                 }
 609                 else {
 610                         DBG((dbg, LEVEL_3, "\tsearching def for %+F at %+F\n", use, get_nodes_block(use)));
 611                         search_def_at_block(env, use);
 612                 }
 613
 614                 stat_ev_cnt_inc(uses);
 615         }
 616
 617         be_timer_pop(T_SSA_CONSTR);
 618
 619         stat_ev_tim_pop("bessaconstr_fix_time");
 620         stat_ev_cnt_done(uses, "bessaconstr_uses");
 621 }
 622
 623 void be_ssa_construction_fix_users(be_ssa_construction_env_t *env, ir_node *value)
 624 {
 625         be_ssa_construction_fix_users_array(env, &value, 1);
 626 }
 627
 628
 629 void be_ssa_construction_update_liveness_phis(be_ssa_construction_env_t *env,
 630                                               be_lv_t *lv)
 631 {
 632         int i, n;
 633
 634         be_timer_push(T_SSA_CONSTR);
 635
 636         n = ARR_LEN(env->new_phis);
 637         for (i = 0; i < n; ++i) {
 638                 ir_node *phi = env->new_phis[i];
 639                 be_liveness_introduce(lv, phi);
 640         }
 641
 642         be_timer_pop(T_SSA_CONSTR);
 643 }
 644
 645 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_ssaconstr)
 646 void be_init_ssaconstr(void)
 647 {
 648         FIRM_DBG_REGISTER(dbg, "firm.be.ssaconstr");
 649 }