nsz Git - libfirm/blob - ir/ir/irgwalk.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   Functions for traversing ir graphs
  23  * @author  Boris Boesler, Goetz Lindenmaier, Michael Beck
  24  * @version $Id$
  25  * @brief
  26  *  traverse an ir graph
  27  *  - execute the pre function before recursion
  28  *  - execute the post function after recursion
  29  */
  30 #include "config.h"
  31
  32 #include <stdlib.h>
  33
  34 #include "irnode_t.h"
  35 #include "irgraph_t.h"
  36 #include "irprog.h"
  37 #include "irgwalk.h"
  38 #include "irhooks.h"
  39 #include "ircgcons.h"
  40 #include "entity_t.h"
  41
  42 #include "error.h"
  43 #include "pset_new.h"
  44 #include "array.h"
  45
  46 #ifdef INTERPROCEDURAL_VIEW
  47 /**
  48  * Walk over an interprocedural graph (callgraph).
  49  * Visits only graphs in irg_set.
  50  */
  51 static void irg_walk_cg(ir_node * node, ir_visited_t visited,
  52                         pset_new_t *irg_set, irg_walk_func *pre,
  53                         irg_walk_func *post, void * env)
  54 {
  55         int i;
  56         ir_graph * rem = current_ir_graph;
  57         ir_node * pred;
  58
  59         assert(node && node->kind == k_ir_node);
  60         if (get_irn_visited(node) >= visited) return;
  61
  62         set_irn_visited(node, visited);
  63
  64         if (pre) pre(node, env);
  65
  66         pred = skip_Proj(node);
  67         if (is_CallBegin(pred)            ||
  68             get_irn_op(pred) == op_EndReg ||
  69             get_irn_op(pred) == op_EndExcept) {
  70                 current_ir_graph = get_irn_irg(pred);
  71         }
  72
  73         if (is_no_Block(node)) { /* not block */
  74                 irg_walk_cg(get_nodes_block(node), visited, irg_set, pre, post, env);
  75         }
  76
  77         if (is_Block(node)) { /* block */
  78                 for (i = get_irn_arity(node) - 1; i >= 0; --i) {
  79                         ir_node * exec = get_irn_n(node, i);
  80                         ir_node * pred = skip_Proj(exec);
  81                         if ((
  82                               !is_CallBegin(pred)           &&
  83                               get_irn_op(pred) != op_EndReg &&
  84                               get_irn_op(pred) != op_EndExcept
  85                             ) || pset_new_contains(irg_set, get_irn_irg(pred))) {
  86                                 irg_walk_cg(exec, visited, irg_set, pre, post, env);
  87                         }
  88                 }
  89         } else if (is_Filter(node)) { /* filter */
  90                 for (i = get_irn_arity(node) - 1; i >= 0; --i) {
  91                         ir_node * pred = get_irn_n(node, i);
  92                         if (is_Unknown(pred) || is_Bad(pred)) {
  93                                 irg_walk_cg(pred, visited, irg_set, pre, post, env);
  94                         } else {
  95                                 ir_node * exec;
  96                                 exec = skip_Proj(get_Block_cfgpred(get_nodes_block(node), i));
  97
  98                                 if (is_Bad(exec)) {
  99                                         continue;
 100                                 }
 101
 102                                 assert(is_CallBegin(exec)            ||
 103                                        get_irn_op(exec) == op_EndReg ||
 104                                        get_irn_op(exec) == op_EndExcept);
 105                                 if (pset_new_contains(irg_set, get_irn_irg(exec))) {
 106                                         current_ir_graph = get_irn_irg(exec);
 107                                         irg_walk_cg(pred, visited, irg_set, pre, post, env);
 108                                         current_ir_graph = rem;
 109                                 }
 110                         }
 111                 }
 112         } else {                      /* everything else */
 113                 for (i = get_irn_arity(node) - 1; i >= 0; --i) {
 114                         irg_walk_cg(get_irn_n(node, i), visited, irg_set, pre, post, env);
 115                 }
 116         }
 117
 118         if (post) post(node, env);
 119
 120         current_ir_graph = rem;
 121 }
 122
 123 /**
 124  * Insert all ir_graphs in irg_set, that are (transitive) reachable.
 125  */
 126 static void collect_irgs(ir_node * node, pset_new_t *irg_set)
 127 {
 128         if (is_Call(node)) {
 129                 int i;
 130                 for (i = get_Call_n_callees(node) - 1; i >= 0; --i) {
 131                         ir_entity * ent = get_Call_callee(node, i);
 132                         ir_graph * irg = get_entity_irg(ent);
 133                         if (irg && !pset_new_contains(irg_set, irg)) {
 134                                 pset_new_insert(irg_set, irg);
 135                                 irg_walk_graph(irg, (irg_walk_func *) collect_irgs, NULL, irg_set);
 136                         }
 137                 }
 138         }
 139 }
 140 #endif
 141
 142 /**
 143  * specialized version of irg_walk_2, called if only pre callback exists
 144  *
 145  * @return number of visited nodes
 146  */
 147 static unsigned irg_walk_2_pre(ir_node *node, irg_walk_func *pre, void *env)
 148 {
 149         int i;
 150         unsigned cnt = 1;
 151         ir_graph *irg = get_irn_irg(node);
 152
 153         set_irn_visited(node, irg->visited);
 154
 155         pre(node, env);
 156
 157         if (node->op != op_Block) {
 158                 ir_node *pred = get_irn_n(node, -1);
 159                 if (pred->visited < irg->visited)
 160                         cnt += irg_walk_2_pre(pred, pre, env);
 161         }
 162         for (i = get_irn_arity(node) - 1; i >= 0; --i) {
 163                 ir_node *pred = get_irn_n(node, i);
 164                 if (pred->visited < irg->visited)
 165                         cnt += irg_walk_2_pre(pred, pre, env);
 166         }
 167         return cnt;
 168 }
 169
 170 /**
 171  * specialized version of irg_walk_2, called if only post callback exists
 172  *
 173  * @return number of visited nodes
 174  */
 175 static unsigned irg_walk_2_post(ir_node *node, irg_walk_func *post, void *env)
 176 {
 177         int i;
 178         unsigned cnt = 1;
 179         ir_graph *irg = get_irn_irg(node);
 180
 181         set_irn_visited(node, irg->visited);
 182
 183         if (node->op != op_Block) {
 184                 ir_node *pred = get_irn_n(node, -1);
 185                 if (pred->visited < irg->visited)
 186                         cnt += irg_walk_2_post(pred, post, env);
 187         }
 188         for (i = get_irn_arity(node) - 1; i >= 0; --i) {
 189                 ir_node *pred = get_irn_n(node, i);
 190                 if (pred->visited < irg->visited)
 191                         cnt += irg_walk_2_post(pred, post, env);
 192         }
 193
 194         post(node, env);
 195
 196         return cnt;
 197 }
 198
 199 /**
 200  * specialized version of irg_walk_2, called if pre and post callbacks exist
 201  *
 202  * @return number of visited nodes
 203  */
 204 static unsigned irg_walk_2_both(ir_node *node, irg_walk_func *pre,
 205                                 irg_walk_func *post, void *env)
 206 {
 207         int i;
 208         unsigned cnt = 1;
 209         ir_graph *irg = get_irn_irg(node);
 210
 211         set_irn_visited(node, irg->visited);
 212
 213         pre(node, env);
 214
 215         if (node->op != op_Block) {
 216                 ir_node *pred = get_irn_n(node, -1);
 217                 if (pred->visited < irg->visited)
 218                         cnt += irg_walk_2_both(pred, pre, post, env);
 219         }
 220         for (i = get_irn_arity(node) - 1; i >= 0; --i) {
 221                 ir_node *pred = get_irn_n(node, i);
 222                 if (pred->visited < irg->visited)
 223                         cnt += irg_walk_2_both(pred, pre, post, env);
 224         }
 225
 226         post(node, env);
 227
 228         return cnt;
 229 }
 230
 231 /**
 232  * Intraprozedural graph walker.
 233  *
 234  * @return number of visited nodes
 235  */
 236 unsigned irg_walk_2(ir_node *node, irg_walk_func *pre, irg_walk_func *post,
 237                     void *env)
 238 {
 239         if (irn_visited(node))
 240                 return 0;
 241
 242         if      (!post) return irg_walk_2_pre (node, pre, env);
 243         else if (!pre)  return irg_walk_2_post(node, post, env);
 244         else            return irg_walk_2_both(node, pre, post, env);
 245 }
 246
 247 /* a counter */
 248 static unsigned nodes_touched = 0;
 249
 250 void irg_walk_core(ir_node *node, irg_walk_func *pre, irg_walk_func *post,
 251                    void *env)
 252 {
 253         assert(is_ir_node(node));
 254
 255 #ifdef INTERPROCEDURAL_VIEW
 256         if (get_interprocedural_view()) {
 257                 pset_new_t           irg_set;
 258                 pset_new_iterator_t  iter;
 259                 ir_visited_t         visited;
 260                 ir_graph            *irg;
 261                 assert(get_irp_ip_view_state() == ip_view_valid);
 262
 263                 pset_new_init(&irg_set);
 264                 set_interprocedural_view(0);
 265                 pset_new_insert(&irg_set, current_ir_graph);
 266                 irg_walk(node, (irg_walk_func *) collect_irgs, NULL, &irg_set);
 267                 set_interprocedural_view(1);
 268                 visited = get_max_irg_visited() + 1;
 269
 270                 foreach_pset_new(&irg_set, irg, iter) {
 271                         set_irg_visited(irg, visited);
 272                 }
 273                 irg_walk_cg(node, visited, &irg_set, pre, post, env);
 274                 pset_new_destroy(&irg_set);
 275         } else {
 276 #endif
 277                 nodes_touched = irg_walk_2(node, pre, post, env);
 278 #ifdef INTERPROCEDURAL_VIEW
 279         }
 280 #endif
 281 }
 282
 283 void irg_walk(ir_node *node, irg_walk_func *pre, irg_walk_func *post,
 284               void *env)
 285 {
 286         ir_reserve_resources(current_ir_graph, IR_RESOURCE_IRN_VISITED);
 287         inc_irg_visited(current_ir_graph);
 288         assert(current_ir_graph == get_irn_irg(node));
 289         irg_walk_core(node, pre, post, env);
 290         ir_free_resources(current_ir_graph, IR_RESOURCE_IRN_VISITED);
 291 }
 292
 293 /*
 294  * walk over a graph
 295  */
 296 void irg_walk_graph(ir_graph *irg, irg_walk_func *pre, irg_walk_func *post, void *env)
 297 {
 298         ir_graph * rem = current_ir_graph;
 299
 300         hook_irg_walk(irg, (generic_func *)pre, (generic_func *)post);
 301         current_ir_graph = irg;
 302         irg_walk(get_irg_end(irg), pre, post, env);
 303         irg->estimated_node_count = nodes_touched;
 304         current_ir_graph = rem;
 305 }
 306
 307 /* Executes irg_walk(end, pre, post, env) for all irgraphs in irprog.
 308    Sets current_ir_graph properly for each walk.  Conserves current
 309    current_ir_graph. */
 310 void all_irg_walk(irg_walk_func *pre, irg_walk_func *post, void *env)
 311 {
 312         int i, n;
 313         ir_graph *irg;
 314
 315         for (i = 0, n = get_irp_n_irgs(); i < n; i++) {
 316                 irg = get_irp_irg(i);
 317                 irg_walk_graph(irg, pre, post, env);
 318         }
 319 }
 320
 321 /***************************************************************************/
 322
 323 /**
 324  * specialized version of irg_walk_in_or_dep_2, called if only pre callback exists
 325  *
 326  * @return number of visited nodes
 327  */
 328 static unsigned irg_walk_in_or_dep_2_pre(ir_node *node, irg_walk_func *pre, void *env)
 329 {
 330         int i;
 331         unsigned cnt = 1;
 332         ir_graph *irg = get_irn_irg(node);
 333
 334         set_irn_visited(node, irg->visited);
 335
 336         pre(node, env);
 337
 338         if (node->op != op_Block) {
 339                 ir_node *pred = get_irn_n(node, -1);
 340                 if (pred->visited < irg->visited)
 341                         cnt += irg_walk_in_or_dep_2_pre(pred, pre, env);
 342         }
 343         for (i = get_irn_ins_or_deps(node) - 1; i >= 0; --i) {
 344                 ir_node *pred = get_irn_in_or_dep(node, i);
 345                 if (pred->visited < irg->visited)
 346                         cnt += irg_walk_in_or_dep_2_pre(pred, pre, env);
 347         }
 348         return cnt;
 349 }
 350
 351 /**
 352  * specialized version of irg_walk_in_or_dep_2, called if only post callback exists
 353  *
 354  * @return number of visited nodes
 355  */
 356 static unsigned irg_walk_in_or_dep_2_post(ir_node *node, irg_walk_func *post, void *env)
 357 {
 358         int i;
 359         unsigned cnt = 1;
 360         ir_graph *irg = get_irn_irg(node);
 361
 362         set_irn_visited(node, irg->visited);
 363
 364         if (node->op != op_Block) {
 365                 ir_node *pred = get_irn_n(node, -1);
 366                 if (pred->visited < irg->visited)
 367                         cnt += irg_walk_in_or_dep_2_post(pred, post, env);
 368         }
 369         for (i = get_irn_ins_or_deps(node) - 1; i >= 0; --i) {
 370                 ir_node *pred = get_irn_in_or_dep(node, i);
 371                 if (pred->visited < irg->visited)
 372                         cnt += irg_walk_in_or_dep_2_post(pred, post, env);
 373         }
 374
 375         post(node, env);
 376
 377         return cnt;
 378 }
 379
 380 /**
 381  * specialized version of irg_walk_in_or_dep_2, called if pre and post callbacks exist
 382  *
 383  * @return number of visited nodes
 384  */
 385 static unsigned irg_walk_in_or_dep_2_both(ir_node *node, irg_walk_func *pre, irg_walk_func *post, void *env)
 386 {
 387         int i;
 388         unsigned cnt = 1;
 389         ir_graph *irg = get_irn_irg(node);
 390
 391         set_irn_visited(node, irg->visited);
 392
 393         pre(node, env);
 394
 395         if (node->op != op_Block) {
 396                 ir_node *pred = get_irn_n(node, -1);
 397                 if (pred->visited < irg->visited)
 398                         cnt += irg_walk_in_or_dep_2_both(pred, pre, post, env);
 399         }
 400         for (i = get_irn_ins_or_deps(node) - 1; i >= 0; --i) {
 401                 ir_node *pred = get_irn_in_or_dep(node, i);
 402                 if (pred->visited < irg->visited)
 403                         cnt += irg_walk_in_or_dep_2_both(pred, pre, post, env);
 404         }
 405
 406         post(node, env);
 407
 408         return cnt;
 409 }
 410
 411 /**
 412  * Intraprozedural graph walker. Follows dependency edges as well.
 413  *
 414  * @return number of visited nodes
 415  */
 416 static unsigned irg_walk_in_or_dep_2(ir_node *node, irg_walk_func *pre, irg_walk_func *post, void *env)
 417 {
 418         if (irn_visited(node))
 419                 return 0;
 420
 421         if      (! post) return irg_walk_in_or_dep_2_pre (node, pre, env);
 422         else if (! pre)  return irg_walk_in_or_dep_2_post(node, post, env);
 423         else             return irg_walk_in_or_dep_2_both(node, pre, post, env);
 424 }
 425
 426 /*
 427  * Generic graph walker. Follows dependency edges as well.
 428  */
 429 void irg_walk_in_or_dep(ir_node *node, irg_walk_func *pre, irg_walk_func *post, void *env)
 430 {
 431         assert(is_ir_node(node));
 432
 433         if (get_interprocedural_view()) {
 434                 assert(0 && "This is not yet implemented.");
 435         } else {
 436                 ir_reserve_resources(current_ir_graph, IR_RESOURCE_IRN_VISITED);
 437                 inc_irg_visited(current_ir_graph);
 438                 nodes_touched = irg_walk_in_or_dep_2(node, pre, post, env);
 439                 ir_free_resources(current_ir_graph, IR_RESOURCE_IRN_VISITED);
 440         }
 441 }
 442
 443 /*
 444  * Walk over a graph. Follow all edges (including dependencies)
 445  */
 446 void irg_walk_in_or_dep_graph(ir_graph *irg, irg_walk_func *pre, irg_walk_func *post, void *env)
 447 {
 448         ir_graph * rem = current_ir_graph;
 449
 450         hook_irg_walk(irg, (generic_func *)pre, (generic_func *)post);
 451         current_ir_graph = irg;
 452         irg_walk_in_or_dep(get_irg_end(irg), pre, post, env);
 453         irg->estimated_node_count = nodes_touched;
 454         current_ir_graph = rem;
 455 }
 456
 457 /***************************************************************************/
 458
 459 /**
 460  * Returns current_ir_graph and sets it to the irg of predecessor index
 461  * of node n.
 462  */
 463 static inline ir_graph * switch_irg(ir_node *n, int index)
 464 {
 465         ir_graph *old_current = current_ir_graph;
 466
 467         if (get_interprocedural_view()) {
 468                 /* Only Filter and Block nodes can have predecessors in other graphs. */
 469                 if (is_Filter(n))
 470                         n = get_nodes_block(n);
 471                 if (is_Block(n)) {
 472                         ir_node *cfop = skip_Proj(get_Block_cfgpred(n, index));
 473                         if (is_ip_cfop(cfop)) {
 474                                 current_ir_graph = get_irn_irg(cfop);
 475                         }
 476                 }
 477         }
 478
 479         return old_current;
 480 }
 481
 482 #ifdef INTERPROCEDURAL_VIEW
 483 static void cg_walk_2(ir_node *node, irg_walk_func *pre, irg_walk_func *post, void * env)
 484 {
 485         int i;
 486         ir_graph *rem = NULL;
 487         assert(node);
 488
 489         if (get_irn_visited(node) < get_irg_visited(current_ir_graph)) {
 490                 set_irn_visited(node, get_irg_visited(current_ir_graph));
 491
 492                 if (pre) pre(node, env);
 493
 494                 if (is_no_Block(node))
 495                         cg_walk_2(get_nodes_block(node), pre, post, env);
 496                 for (i = get_irn_arity(node) - 1; i >= 0; --i) {
 497                         rem = switch_irg(node, i);  /* @@@ AS: Is this wrong? We do have to
 498                                                     switch to the irg of the predecessor, don't we? */
 499                         cg_walk_2(get_irn_n(node, i), pre, post, env);
 500                         current_ir_graph = rem;
 501                 }
 502
 503                 if (post) post(node, env);
 504         }
 505 }
 506
 507 /* Walks all irgs in interprocedural view.  Visits each node only once. */
 508 void cg_walk(irg_walk_func *pre, irg_walk_func *post, void *env)
 509 {
 510         int i;
 511         ir_graph *rem = current_ir_graph;
 512         int rem_view = get_interprocedural_view();
 513
 514         set_interprocedural_view(1);
 515
 516         inc_max_irg_visited();
 517         /* Fix all irg_visited flags */
 518         for (i = 0; i < get_irp_n_irgs(); i++)
 519                 set_irg_visited(get_irp_irg(i), get_max_irg_visited());
 520
 521         /* Walk starting at unreachable procedures. Only these
 522          * have End blocks visible in interprocedural view. */
 523         for (i = 0; i < get_irp_n_irgs(); i++) {
 524                 ir_node *sb;
 525                 current_ir_graph = get_irp_irg(i);
 526
 527                 sb = get_irg_start_block(current_ir_graph);
 528
 529                 if ((get_Block_n_cfgpreds(sb) > 1) ||
 530                         (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb)) continue;
 531
 532                 cg_walk_2(get_irg_end(current_ir_graph), pre, post, env);
 533         }
 534
 535         /* Check whether we walked all procedures: there could be procedures
 536            with cyclic calls but no call from the outside. */
 537         for (i = 0; i < get_irp_n_irgs(); i++) {
 538                 ir_node *sb;
 539                 current_ir_graph = get_irp_irg(i);
 540
 541                 /* Test start block: if inner procedure end and end block are not
 542                 * visible and therefore not marked. */
 543                 sb = get_irg_start_block(current_ir_graph);
 544                 if (get_irn_visited(sb) < get_irg_visited(current_ir_graph)) {
 545                         cg_walk_2(sb, pre, post, env);
 546                 }
 547         }
 548
 549         /* Walk all endless loops in inner procedures.
 550          * We recognize an inner procedure if the End node is not visited. */
 551         for (i = 0; i < get_irp_n_irgs(); i++) {
 552                 ir_node *e;
 553                 current_ir_graph = get_irp_irg(i);
 554                 e = get_irg_end(current_ir_graph);
 555                 if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
 556                         int j;
 557                         /* Don't visit the End node. */
 558                         for (j = 0; j < get_End_n_keepalives(e); j++)
 559                                 cg_walk_2(get_End_keepalive(e, j), pre, post, env);
 560                 }
 561         }
 562
 563         set_interprocedural_view(rem_view);
 564         current_ir_graph = rem;
 565 }
 566 #endif
 567
 568
 569 /***************************************************************************/
 570
 571 /* Walks back from n until it finds a real cf op. */
 572 static ir_node *get_cf_op(ir_node *n)
 573 {
 574         while (!is_cfop(n) && !is_fragile_op(n) && !is_Bad(n)) {
 575                 n = skip_Id(n);
 576                 n = skip_Tuple(n);
 577                 n = skip_Proj(n);
 578         }
 579         return n;
 580 }
 581
 582 static void irg_block_walk_2(ir_node *node, irg_walk_func *pre,
 583                              irg_walk_func *post, void *env)
 584 {
 585         int i;
 586
 587         if (Block_block_visited(node))
 588                 return;
 589         mark_Block_block_visited(node);
 590
 591         if (pre)
 592                 pre(node, env);
 593
 594         for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
 595                 /* find the corresponding predecessor block. */
 596                 ir_node *pred = get_cf_op(get_Block_cfgpred(node, i));
 597                 pred = get_nodes_block(pred);
 598                 if (get_irn_opcode(pred) == iro_Block) {
 599                         /* recursion */
 600                         irg_block_walk_2(pred, pre, post, env);
 601                 } else {
 602                         assert(get_irn_opcode(pred) == iro_Bad);
 603                 }
 604         }
 605
 606         if (post)
 607                 post(node, env);
 608 }
 609
 610
 611 /* walks only over Block nodes in the graph.  Has it's own visited
 612    flag, so that it can be interleaved with the other walker.         */
 613 void irg_block_walk(ir_node *node, irg_walk_func *pre, irg_walk_func *post, void *env)
 614 {
 615         ir_graph *irg = get_irn_irg(node);
 616         ir_node *block, *pred;
 617         int i;
 618
 619         hook_irg_block_walk(irg, node, (generic_func *)pre, (generic_func *)post);
 620
 621         assert(node);
 622         assert(!get_interprocedural_view());   /* interprocedural_view not implemented, because it
 623                                                 * interleaves with irg_walk */
 624         ir_reserve_resources(irg, IR_RESOURCE_BLOCK_VISITED);
 625         inc_irg_block_visited(irg);
 626         block = is_Block(node) ? node : get_nodes_block(node);
 627         assert(is_Block(block));
 628         irg_block_walk_2(block, pre, post, env);
 629
 630         /* keepalive: the endless loops ... */
 631         if (is_End(node)) {
 632                 int arity = get_irn_arity(node);
 633                 for (i = 0; i < arity; i++) {
 634                         pred = get_irn_n(node, i);
 635                         if (!is_Block(pred)) {
 636                                 pred = get_nodes_block(pred);
 637                                 if (!is_Block(pred)) {
 638                                         /* if rare cases a kept node might have a bad block input */
 639                                         continue;
 640                                 }
 641                         }
 642                         /* Sometimes the blocks died, but are still reachable through kept nodes.
 643                          * Make sure the algorithms that try to remove these reach them. */
 644                         irg_block_walk_2(pred, pre, post, env);
 645                 }
 646         }
 647
 648         ir_free_resources(irg, IR_RESOURCE_BLOCK_VISITED);
 649 }
 650
 651 /*
 652  * walk over a graph block wise
 653  */
 654 void irg_block_walk_graph(ir_graph *irg, irg_walk_func *pre,
 655                           irg_walk_func *post, void *env)
 656 {
 657         ir_graph * rem = current_ir_graph;
 658         current_ir_graph = irg;
 659         irg_block_walk(get_irg_end(irg), pre, post, env);
 660         current_ir_graph = rem;
 661 }
 662
 663 /*
 664  * Additionally walk over all anchors. Do NOT increase the visit flag.
 665  */
 666 void irg_walk_anchors(ir_graph *irg, irg_walk_func *pre, irg_walk_func *post, void *env)
 667 {
 668         ir_graph * rem = current_ir_graph;
 669         current_ir_graph = irg;
 670
 671         inc_irg_visited(irg);
 672         irg_walk_2(irg->anchor, pre, post, env);
 673
 674         current_ir_graph = rem;
 675 }
 676
 677 /********************************************************************/
 678
 679 typedef struct walk_env {
 680         irg_walk_func *pre;
 681         irg_walk_func *post;
 682         void *env;
 683 } walk_env;
 684
 685 static void walk_initializer(ir_initializer_t *initializer, walk_env *env)
 686 {
 687         switch (initializer->kind) {
 688     case IR_INITIALIZER_CONST:
 689         irg_walk(initializer->consti.value, env->pre, env->post, env->env);
 690         return;
 691     case IR_INITIALIZER_TARVAL:
 692     case IR_INITIALIZER_NULL:
 693         return;
 694
 695     case IR_INITIALIZER_COMPOUND: {
 696         size_t i;
 697         for (i = 0; i < initializer->compound.n_initializers; ++i) {
 698             ir_initializer_t *subinitializer
 699                 = initializer->compound.initializers[i];
 700             walk_initializer(subinitializer, env);
 701         }
 702         return;
 703     }
 704         }
 705         panic("invalid initializer found");
 706 }
 707
 708 /**
 709  * Walk to all constant expressions in this entity.
 710  */
 711 static void walk_entity(ir_entity *ent, void *env)
 712 {
 713         walk_env *my_env = (walk_env *)env;
 714
 715         if (ent->initializer != NULL) {
 716                 walk_initializer(ent->initializer, my_env);
 717         } else if (entity_has_compound_ent_values(ent)) {
 718                 int i, n_vals = get_compound_ent_n_values(ent);
 719
 720                 for (i = 0; i < n_vals; i++)
 721                         irg_walk(get_compound_ent_value(ent, i), my_env->pre, my_env->post, my_env->env);
 722         }
 723 }
 724
 725 /* Walks over all code in const_code_irg. */
 726 void walk_const_code(irg_walk_func *pre, irg_walk_func *post, void *env)
 727 {
 728         int i, j, n_types;
 729         walk_env my_env;
 730         ir_segment_t s;
 731
 732         ir_graph *rem = current_ir_graph;
 733         current_ir_graph = get_const_code_irg();
 734         inc_irg_visited(current_ir_graph);
 735
 736         my_env.pre = pre;
 737         my_env.post = post;
 738         my_env.env = env;
 739
 740         /* Walk all types that can contain constant entities.  */
 741         for (s = IR_SEGMENT_FIRST; s <= IR_SEGMENT_LAST; s++)
 742                 walk_types_entities(get_segment_type(s), &walk_entity, &my_env);
 743         n_types = get_irp_n_types();
 744         for (i = 0; i < n_types; i++)
 745                 walk_types_entities(get_irp_type(i), &walk_entity, &my_env);
 746         for (i = 0; i < get_irp_n_irgs(); i++)
 747                 walk_types_entities(get_irg_frame_type(get_irp_irg(i)), &walk_entity, &my_env);
 748
 749         /* Walk constant array bounds. */
 750         for (i = 0; i < n_types; i++) {
 751                 ir_type *tp = get_irp_type(i);
 752                 if (is_Array_type(tp)) {
 753                         int n_dim = get_array_n_dimensions(tp);
 754                         for (j = 0; j < n_dim; j++) {
 755                                 ir_node *n = get_array_lower_bound(tp, j);
 756                                 if (n) irg_walk(n, pre, post, env);
 757                                 n = get_array_upper_bound(tp, j);
 758                                 if (n) irg_walk(n, pre, post, env);
 759                         }
 760                 }
 761         }
 762
 763         current_ir_graph = rem;
 764 }