nsz Git - libfirm/blob - ir/ana/irdom.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     Construct and access dominator / post dominator tree.
  23  * @author    Goetz Lindenmaier, Michael Beck, Rubino Geiss
  24  * @date      2.2002
  25  * @version   $Id$
  26  */
  27 #include "config.h"
  28
  29 #include <string.h>
  30
  31 #include "irouts.h"
  32
  33 #include "xmalloc.h"
  34 #include "irgwalk.h"
  35 #include "irdom_t.h"
  36 #include "irgraph_t.h"   /* To access state field. */
  37 #include "irnode_t.h"
  38 #include "ircons_t.h"
  39 #include "array_t.h"
  40 #include "iredges.h"
  41
  42
  43 #define get_dom_info(bl)  (&(bl)->attr.block.dom)
  44 #define get_pdom_info(bl) (&(bl)->attr.block.pdom)
  45
  46 /*--------------------------------------------------------------------*/
  47 /** Accessing the dominator and post dominator data structures       **/
  48 /*--------------------------------------------------------------------*/
  49
  50 ir_node *get_Block_idom(const ir_node *bl) {
  51         assert(is_Block(bl));
  52         if (get_Block_dom_depth(bl) == -1) {
  53                 /* This block is not reachable from Start */
  54                 return new_Bad();
  55         }
  56         return get_dom_info(bl)->idom;
  57 }
  58
  59 void set_Block_idom(ir_node *bl, ir_node *n) {
  60         ir_dom_info *bli = get_dom_info(bl);
  61
  62         assert(is_Block(bl));
  63
  64         /* Set the immediate dominator of bl to n */
  65         bli->idom = n;
  66
  67         /*
  68          * If we don't set the root of the dominator tree
  69          * Append bl to the dominates queue of n.
  70          */
  71         if(n != NULL) {
  72                 ir_dom_info *ni = get_dom_info(n);
  73
  74                 bli->next = ni->first;
  75                 ni->first = bl;
  76         }
  77 }
  78
  79 ir_node *get_Block_ipostdom(const ir_node *bl) {
  80         assert(is_Block(bl));
  81         if (get_Block_postdom_depth(bl) == -1) {
  82                 /* This block is not reachable from Start */
  83                 return new_Bad();
  84         }
  85         return get_pdom_info(bl)->idom;
  86 }
  87
  88 void set_Block_ipostdom(ir_node *bl, ir_node *n) {
  89         ir_dom_info *bli = get_pdom_info(bl);
  90
  91         assert(is_Block(bl));
  92
  93         /* Set the immediate post dominator of bl to n */
  94         bli->idom = n;
  95
  96         /*
  97          * If we don't set the root of the post dominator tree
  98          * Append bl to the post dominates queue of n.
  99          */
 100         if(n != NULL) {
 101                 ir_dom_info *ni = get_pdom_info(n);
 102
 103                 bli->next = ni->first;
 104                 ni->first = bl;
 105         }
 106 }
 107
 108 int get_Block_dom_pre_num(const ir_node *bl) {
 109         assert(is_Block(bl));
 110         return get_dom_info(bl)->pre_num;
 111 }
 112
 113 void set_Block_dom_pre_num(ir_node *bl, int num) {
 114         assert(is_Block(bl));
 115         get_dom_info(bl)->pre_num = num;
 116 }
 117
 118 int get_Block_dom_depth(const ir_node *bl) {
 119         assert(is_Block(bl));
 120         return get_dom_info(bl)->dom_depth;
 121 }
 122
 123 void set_Block_dom_depth(ir_node *bl, int depth) {
 124         assert(is_Block(bl));
 125         get_dom_info(bl)->dom_depth = depth;
 126 }
 127
 128
 129 int get_Block_postdom_pre_num(const ir_node *bl) {
 130         assert(is_Block(bl));
 131         return get_pdom_info(bl)->pre_num;
 132 }
 133
 134 void set_Block_postdom_pre_num(ir_node *bl, int num) {
 135         assert(is_Block(bl));
 136         get_pdom_info(bl)->pre_num = num;
 137 }
 138
 139 int get_Block_postdom_depth(const ir_node *bl) {
 140         assert(is_Block(bl));
 141         return get_pdom_info(bl)->dom_depth;
 142 }
 143
 144 void set_Block_postdom_depth(ir_node *bl, int depth) {
 145         assert(is_Block(bl));
 146         get_pdom_info(bl)->dom_depth = depth;
 147 }
 148
 149 unsigned get_Block_dom_tree_pre_num(const ir_node *bl) {
 150         assert(is_Block(bl));
 151         return get_dom_info(bl)->tree_pre_num;
 152 }
 153
 154 unsigned get_Block_dom_max_subtree_pre_num(const ir_node *bl) {
 155         assert(is_Block(bl));
 156         return get_dom_info(bl)->max_subtree_pre_num;
 157 }
 158
 159 unsigned get_Block_pdom_tree_pre_num(const ir_node *bl) {
 160         assert(is_Block(bl));
 161         return get_pdom_info(bl)->tree_pre_num;
 162 }
 163
 164 unsigned get_Block_pdom_max_subtree_pre_num(const ir_node *bl) {
 165         assert(is_Block(bl));
 166         return get_pdom_info(bl)->max_subtree_pre_num;
 167 }
 168
 169 /* Check, if a block dominates another block. */
 170 int block_dominates(const ir_node *a, const ir_node *b) {
 171         const ir_dom_info *ai, *bi;
 172
 173         if (is_Block(a) && is_Block(b)) {
 174                 ai = get_dom_info(a);
 175                 bi = get_dom_info(b);
 176                 return bi->tree_pre_num - ai->tree_pre_num
 177                         <= ai->max_subtree_pre_num - ai->tree_pre_num;
 178         }
 179
 180         return 0;
 181 }
 182
 183 /* Check, if a block strictly dominates another block. */
 184 int block_strictly_dominates(const ir_node *a, const ir_node *b) {
 185         return (a != b) && block_dominates(a, b);
 186 }
 187
 188 /* Returns the smallest common dominator block of two nodes. */
 189 ir_node *node_smallest_common_dominator(ir_node *a, ir_node *b) {
 190         ir_node *bl_a   = is_Block(a) ? a : get_nodes_block(a);
 191         ir_node *bl_b   = is_Block(b) ? b : get_nodes_block(b);
 192         ir_node *dom_bl = NULL;
 193
 194         /* Check if block of a dominates block of b */
 195         if (block_dominates(bl_a, bl_b))
 196                 dom_bl = bl_a;
 197         /* Check if block of b dominates block of a */
 198         else if (block_dominates(bl_b, bl_a))
 199                 dom_bl = bl_b;
 200         else {
 201                 /* walk up dominator tree and search for first block dominating a and b */
 202                 while (! dom_bl) {
 203                         bl_a = get_Block_idom(bl_a);
 204
 205                         assert(! is_Bad(bl_a) && "block is dead?");
 206
 207                         if (block_dominates(bl_a, bl_b))
 208                                 dom_bl = bl_a;
 209                 }
 210         }
 211
 212         return dom_bl;
 213 }
 214
 215 /* Returns the smallest common dominator block of all users of a node. */
 216 ir_node *node_users_smallest_common_dominator(ir_node *irn, int handle_phi) {
 217         int n, j, i = 0, success;
 218         ir_node **user_blocks, *dom_bl;
 219         const ir_edge_t *edge;
 220
 221         assert(! is_Block(irn) && "WRONG USAGE of node_users_smallest_common_dominator");
 222         assert(edges_activated(get_irn_irg(irn)) && "need edges activated");
 223
 224         n = get_irn_n_edges(irn);
 225
 226         /* get array to hold all block of the node users */
 227         NEW_ARR_A(ir_node *, user_blocks, n);
 228         foreach_out_edge(irn, edge) {
 229                 ir_node *src = get_edge_src_irn(edge);
 230
 231                 if (is_Phi(src) && handle_phi) {
 232                         /* get the corresponding cfg predecessor block if phi handling requested */
 233                         j  = get_edge_src_pos(edge);
 234                         assert(j >= 0 && "kaputt");
 235                         user_blocks[i++] = get_Block_cfgpred_block(get_nodes_block(src), j);
 236                 }
 237                 else
 238                         user_blocks[i++] = is_Block(src) ? src : get_nodes_block(src);
 239         }
 240
 241         assert(i == n && "get_irn_n_edges probably broken");
 242
 243         /* in case of only one user: return the block of the user */
 244         if (n == 1)
 245                 return user_blocks[0];
 246
 247         i = 0;
 248         /* search the smallest block dominating all user blocks */
 249         do {
 250                 dom_bl  = node_smallest_common_dominator(user_blocks[i], user_blocks[i + 1]);
 251                 success = 1;
 252
 253                 /* check if this block dominates all remaining blocks as well */
 254                 for (j = i + 2; j < n; j++) {
 255                         if (! block_dominates(dom_bl, user_blocks[j]))
 256                                 success = 0;
 257                 }
 258
 259                 if (success)
 260                         break;
 261
 262                 /* inherit the dominator block of the first (i + 1) users */
 263                 user_blocks[++i] = dom_bl;
 264         } while (i < n - 1);
 265
 266         assert(success && "no block found dominating all users");
 267
 268         return dom_bl;
 269 }
 270
 271
 272 /* Get the first node in the list of nodes dominated by a given block. */
 273 ir_node *get_Block_dominated_first(const ir_node *bl) {
 274         assert(is_Block(bl));
 275         return get_dom_info(bl)->first;
 276 }
 277
 278 /* Get the next node in a list of nodes which are dominated by some
 279  * other node. */
 280 ir_node *get_Block_dominated_next(const ir_node *bl) {
 281         assert(is_Block(bl));
 282         return get_dom_info(bl)->next;
 283 }
 284
 285 /* Check, if a block post dominates another block. */
 286 int block_postdominates(const ir_node *a, const ir_node *b) {
 287         const ir_dom_info *ai, *bi;
 288
 289         if (is_Block(a) && is_Block(b)) {
 290                 ai = get_pdom_info(a);
 291                 bi = get_pdom_info(b);
 292                 return bi->tree_pre_num - ai->tree_pre_num
 293                         <= ai->max_subtree_pre_num - ai->tree_pre_num;
 294         }
 295
 296         return 0;
 297 }
 298
 299 /* Check, if a block strictly dominates another block. */
 300 int block_strictly_postdominates(const ir_node *a, const ir_node *b) {
 301         return (a != b) && block_postdominates(a, b);
 302 }
 303
 304
 305 /* Get the first node in the list of nodes post dominated by a given block. */
 306 ir_node *get_Block_postdominated_first(const ir_node *bl) {
 307         assert(is_Block(bl));
 308         return get_pdom_info(bl)->first;
 309 }
 310
 311 /* Get the next node in a list of nodes which are post dominated by some
 312  * other node. */
 313 ir_node *get_Block_postdominated_next(const ir_node *bl) {
 314         assert(is_Block(bl));
 315         return get_pdom_info(bl)->next;
 316 }
 317
 318 /* Visit all nodes in the dominator subtree of a given node. */
 319 void dom_tree_walk(ir_node *bl, irg_walk_func *pre,
 320                 irg_walk_func *post, void *env)
 321 {
 322         ir_node *p;
 323
 324         if(pre)
 325                 pre(bl, env);
 326
 327         dominates_for_each(bl, p) {
 328                 dom_tree_walk(p, pre, post, env);
 329         }
 330
 331         if(post)
 332                 post(bl, env);
 333 }
 334
 335 /* Visit all nodes in the post dominator subtree of a given node. */
 336 void postdom_tree_walk(ir_node *bl, irg_walk_func *pre,
 337                 irg_walk_func *post, void *env)
 338 {
 339         ir_node *p;
 340
 341         if(pre)
 342                 pre(bl, env);
 343
 344         postdominates_for_each(bl, p) {
 345                 postdom_tree_walk(p, pre, post, env);
 346         }
 347
 348         if(post)
 349                 post(bl, env);
 350 }
 351
 352 /* Walk over the dominator tree of an irg starting at the root. */
 353 void dom_tree_walk_irg(ir_graph *irg, irg_walk_func *pre,
 354                 irg_walk_func *post, void *env)
 355 {
 356         /* The root of the dominator tree should be the Start block. */
 357         ir_node *root = get_irg_start_block(irg);
 358
 359   assert(irg->dom_state == dom_consistent
 360                         && "The dominators of the irg must be consistent");
 361         assert(root && "The start block of the graph is NULL?");
 362         assert(get_dom_info(root)->idom == NULL
 363                         && "The start node in the graph must be the root of the dominator tree");
 364         dom_tree_walk(root, pre, post, env);
 365 }
 366
 367 /* Walk over the post dominator tree of an irg starting at the root. */
 368 void postdom_tree_walk_irg(ir_graph *irg, irg_walk_func *pre,
 369                 irg_walk_func *post, void *env)
 370 {
 371         /* The root of the dominator tree should be the End block. */
 372         ir_node *root = get_irg_end_block(irg);
 373
 374         assert(irg->pdom_state == dom_consistent
 375                         && "The dominators of the irg must be consistent");
 376         assert(root && "The end block of the graph is NULL?");
 377         assert(get_pdom_info(root)->idom == NULL
 378                         && "The End block node in the graph must be the root of the post dominator tree");
 379         postdom_tree_walk(root, pre, post, env);
 380 }
 381
 382
 383 static void assign_tree_dom_pre_order(ir_node *bl, void *data)
 384 {
 385         unsigned *num = data;
 386         ir_dom_info *bi = get_dom_info(bl);
 387
 388         bi->tree_pre_num = (*num)++;
 389 }
 390
 391 static void assign_tree_dom_pre_order_max(ir_node *bl, void *data)
 392 {
 393         ir_dom_info *bi = get_dom_info(bl);
 394         ir_node *p;
 395         unsigned max = 0;
 396         unsigned children = 0;
 397         (void) data;
 398
 399         for(p = bi->first; p; p = get_dom_info(p)->next) {
 400                 unsigned max_p = get_dom_info(p)->max_subtree_pre_num;
 401                 max = max > max_p ? max : max_p;
 402                 children++;
 403         }
 404
 405         bi->max_subtree_pre_num = children > 0 ? max : bi->tree_pre_num;
 406         assert(bi->max_subtree_pre_num >= bi->tree_pre_num);
 407 }
 408
 409 static void assign_tree_postdom_pre_order(ir_node *bl, void *data)
 410 {
 411         unsigned *num = data;
 412         ir_dom_info *bi = get_pdom_info(bl);
 413
 414         bi->tree_pre_num = (*num)++;
 415 }
 416
 417 static void assign_tree_postdom_pre_order_max(ir_node *bl, void *data)
 418 {
 419         ir_dom_info *bi = get_pdom_info(bl);
 420         ir_node *p;
 421         unsigned max = 0;
 422         unsigned children = 0;
 423         (void) data;
 424
 425         for(p = bi->first; p; p = get_pdom_info(p)->next) {
 426                 unsigned max_p = get_pdom_info(p)->max_subtree_pre_num;
 427                 max = max > max_p ? max : max_p;
 428                 children++;
 429         }
 430
 431         bi->max_subtree_pre_num = children > 0 ? max : bi->tree_pre_num;
 432         assert(bi->max_subtree_pre_num >= bi->tree_pre_num);
 433 }
 434
 435 /*--------------------------------------------------------------------*/
 436 /*  Building and Removing the dominator data structure                */
 437 /*--------------------------------------------------------------------*/
 438
 439 /**
 440  * count the number of blocks and clears the post dominance info
 441  */
 442 static void count_and_init_blocks_pdom(ir_node *bl, void *env) {
 443         int *n_blocks = (int *) env;
 444         (*n_blocks) ++;
 445
 446         memset(get_pdom_info(bl), 0, sizeof(ir_dom_info));
 447         set_Block_ipostdom(bl, NULL);
 448         set_Block_postdom_pre_num(bl, -1);
 449         set_Block_postdom_depth(bl, -1);
 450 }
 451
 452 /** temporary type used while constructing the dominator / post dominator tree. */
 453 typedef struct tmp_dom_info {
 454         ir_node *block;               /**< backlink */
 455
 456         struct tmp_dom_info *semi;    /**< semidominator */
 457         struct tmp_dom_info *parent;
 458         struct tmp_dom_info *label;   /**< used for LINK and EVAL */
 459         struct tmp_dom_info *ancestor;/**< used for LINK and EVAL */
 460         struct tmp_dom_info *dom;     /**< After step 3, if the semidominator of w is
 461                                            its immediate dominator, then w->dom is the
 462                                            immediate dominator of w.  Otherwise w->dom
 463                                            is a vertex v whose number is smaller than
 464                                            w and whose immediate dominator is also w's
 465                                            immediate dominator. After step 4, w->dom
 466                                            is the immediate dominator of w.  */
 467         struct tmp_dom_info *bucket;  /**< set of vertices with same semidominator */
 468 } tmp_dom_info;
 469
 470 /** Struct to pass info through walker. */
 471 typedef struct {
 472         tmp_dom_info *d;
 473         int used;
 474 } dom_env;
 475
 476
 477 /**
 478  * Walks Blocks along the out data structure.  If recursion started with
 479  * Start block misses control dead blocks.
 480  */
 481 static void init_tmp_dom_info(ir_node *bl, tmp_dom_info *parent,
 482                               tmp_dom_info *tdi_list, int *used, int n_blocks) {
 483         tmp_dom_info *tdi;
 484         int i;
 485
 486         assert(is_Block(bl));
 487         if (get_irg_block_visited(current_ir_graph) == get_Block_block_visited(bl))
 488           return;
 489         mark_Block_block_visited(bl);
 490         set_Block_dom_pre_num(bl, *used);
 491
 492         assert(*used < n_blocks);
 493         tdi = &tdi_list[*used];
 494         ++(*used);
 495
 496         tdi->semi     = tdi;
 497         tdi->label    = tdi;
 498         tdi->ancestor = NULL;
 499         tdi->bucket   = NULL;
 500         tdi->parent   = parent;
 501         tdi->block    = bl;
 502
 503         /* Iterate */
 504         for (i = get_Block_n_cfg_outs_ka(bl) - 1; i >= 0; --i) {
 505                 ir_node *pred = get_Block_cfg_out_ka(bl, i);
 506                 /* can happen for half-optimized dead code (I've seen this in student
 507                    projects */
 508                 if (!is_Block(pred))
 509                         continue;
 510
 511                 init_tmp_dom_info(pred, tdi, tdi_list, used, n_blocks);
 512         }
 513 }
 514
 515 /**
 516  * Walks Blocks along the control flow.  If recursion started with
 517  * End block misses blocks in endless loops.
 518  */
 519 static void init_tmp_pdom_info(ir_node *bl, tmp_dom_info *parent,
 520                                tmp_dom_info *tdi_list, int* used, int n_blocks) {
 521         tmp_dom_info *tdi;
 522         int i;
 523
 524         assert(is_Block(bl));
 525         if (get_irg_block_visited(current_ir_graph) == get_Block_block_visited(bl))
 526           return;
 527         mark_Block_block_visited(bl);
 528         set_Block_postdom_pre_num(bl, *used);
 529
 530         assert(*used < n_blocks);
 531         tdi = &tdi_list[*used];
 532         ++(*used);
 533
 534         tdi->semi = tdi;
 535         tdi->label = tdi;
 536         tdi->ancestor = NULL;
 537         tdi->bucket = NULL;
 538         tdi->parent = parent;
 539         tdi->block = bl;
 540
 541         /* Iterate */
 542         for (i = get_Block_n_cfgpreds(bl) - 1; i >= 0; --i) {
 543                 ir_node *pred = get_Block_cfgpred_block(bl, i);
 544                 if (is_Bad(pred))
 545                         continue;
 546                 assert(is_Block(pred));
 547                 init_tmp_pdom_info(pred, tdi, tdi_list, used, n_blocks);
 548         }
 549
 550         /* Handle keep-alives. Note that the preprocessing
 551            in init_construction() had already killed all
 552            phantom keep-alive edges. All remaining block keep-alives
 553            are really edges to endless loops.
 554          */
 555         if (bl == get_irg_end_block(current_ir_graph)) {
 556                 ir_node *end = get_irg_end(current_ir_graph);
 557
 558                 for (i = get_irn_arity(end) - 1; i >= 0; --i) {
 559                         ir_node *pred = get_irn_n(end, i);
 560
 561                         if (is_Block(pred))
 562                                 init_tmp_pdom_info(pred, tdi, tdi_list, used, n_blocks);
 563                 }
 564         }
 565 }
 566
 567 static void dom_compress(tmp_dom_info *v) {
 568         assert (v->ancestor);
 569         if (v->ancestor->ancestor) {
 570                 dom_compress (v->ancestor);
 571                 if (v->ancestor->label->semi < v->label->semi) {
 572                         v->label = v->ancestor->label;
 573                 }
 574                 v->ancestor = v->ancestor->ancestor;
 575         }
 576 }
 577
 578 /**
 579  * if V is a root, return v, else return the vertex u, not being the
 580  * root, with minimum u->semi on the path from v to its root.
 581  */
 582 inline static tmp_dom_info *dom_eval(tmp_dom_info *v) {
 583         if (!v->ancestor) return v;
 584         dom_compress (v);
 585         return v->label;
 586 }
 587
 588 /** make V W's ancestor */
 589 inline static void dom_link(tmp_dom_info *v, tmp_dom_info *w) {
 590         w->ancestor = v;
 591 }
 592
 593 /**
 594  * Walker: count the number of blocks and clears the dominance info
 595  */
 596 static void count_and_init_blocks_dom(ir_node *bl, void *env) {
 597         int *n_blocks = (int *) env;
 598         (*n_blocks) ++;
 599
 600         memset(get_dom_info(bl), 0, sizeof(ir_dom_info));
 601         set_Block_idom(bl, NULL);
 602         set_Block_dom_pre_num(bl, -1);
 603         set_Block_dom_depth(bl, -1);
 604 }
 605
 606 /**
 607  * Initialize the dominance/postdominance construction:
 608  *
 609  * - count the number of blocks
 610  * - clear the dominance info
 611  * - remove Block-keepalives of live blocks to reduce
 612  *   the number of "phantom" block edges
 613  *
 614  * @param irg  the graph
 615  * @param pre  a walker function that will be called for every block in the graph
 616  */
 617 static int init_construction(ir_graph *irg, irg_walk_func *pre) {
 618         ir_graph *rem = current_ir_graph;
 619         ir_node *end;
 620         int arity;
 621         int n_blocks = 0;
 622
 623         current_ir_graph = irg;
 624
 625         /* this visits only the reachable blocks */
 626         irg_block_walk(get_irg_end_block(irg), pre, NULL, &n_blocks);
 627
 628         /* now visit the unreachable (from End) Blocks and remove unnecessary keep-alives */
 629         end   = get_irg_end(irg);
 630         arity = get_End_n_keepalives(end);
 631         if (arity) {    /* we have keep-alives */
 632                 ir_node **in;
 633                 int i, j;
 634
 635                 NEW_ARR_A(ir_node *, in, arity);
 636                 for (i = j = 0; i < arity; i++) {
 637                         ir_node *pred = get_End_keepalive(end, i);
 638
 639                         if (!is_Block(pred)) {
 640                                 pred = get_nodes_block(pred);
 641                                 if (!is_Block(pred)) {
 642                                         /* a node which has a bad block input: kill it */
 643                                         continue;
 644                                 }
 645                         }
 646                         dec_irg_block_visited(irg);
 647                         irg_block_walk(pred, pre, NULL, &n_blocks);
 648                         in[j++] = pred;
 649                 }
 650                 if (j != arity) {
 651                         /* we kill some keep-alives */
 652                         set_End_keepalives(end, j, in);
 653                         set_irg_outs_inconsistent(irg);
 654                 }
 655         }
 656
 657         current_ir_graph = rem;
 658         return n_blocks;
 659 }
 660
 661
 662 /* Computes the dominator trees.  Sets a flag in irg to "dom_consistent".
 663    If the control flow of the graph is changed this flag must be set to
 664    "dom_inconsistent".  */
 665 void compute_doms(ir_graph *irg) {
 666         ir_graph *rem = current_ir_graph;
 667         int n_blocks, used, i, j;
 668         tmp_dom_info *tdi_list;   /* Ein Golf? */
 669
 670         current_ir_graph = irg;
 671
 672         /* Update graph state */
 673         assert(get_irg_phase_state(irg) != phase_building);
 674         irg->dom_state = dom_consistent;
 675
 676         /* Count the number of blocks in the graph. */
 677         n_blocks = init_construction(irg, count_and_init_blocks_dom);
 678
 679         /* Memory for temporary information. */
 680         tdi_list = XMALLOCNZ(tmp_dom_info, n_blocks);
 681
 682         /* We need the out data structure. */
 683         assure_irg_outs(irg);
 684
 685         /* this with a standard walker as passing the parent to the sons isn't
 686            simple. */
 687         used = 0;
 688         inc_irg_block_visited(irg);
 689         init_tmp_dom_info(get_irg_start_block(irg), NULL, tdi_list, &used, n_blocks);
 690         /* If not all blocks are reachable from Start by out edges this assertion
 691            fails.
 692            assert(used == n_blocks && "Precondition for dom construction violated"); */
 693         assert(used <= n_blocks && "Precondition for dom construction violated");
 694         n_blocks = used;
 695
 696
 697         for (i = n_blocks-1; i > 0; i--) {  /* Don't iterate the root, it's done. */
 698                 int irn_arity;
 699                 tmp_dom_info *w = &tdi_list[i];
 700                 tmp_dom_info *v;
 701
 702                 /* Step 2 */
 703                 irn_arity = get_irn_arity(w->block);
 704                 for (j = 0; j < irn_arity;  j++) {
 705                         ir_node *pred = get_Block_cfgpred_block(w->block, j);
 706                         tmp_dom_info *u;
 707
 708                         if (is_Bad(pred) || (get_Block_dom_pre_num (pred) == -1))
 709                                 continue;       /* control-dead */
 710
 711                         u = dom_eval (&tdi_list[get_Block_dom_pre_num(pred)]);
 712                         if (u->semi < w->semi) w->semi = u->semi;
 713                 }
 714
 715                 /* handle keep-alives if we are at the end block */
 716                 if (w->block == get_irg_end_block(irg)) {
 717                         ir_node *end = get_irg_end(irg);
 718
 719                         irn_arity = get_irn_arity(end);
 720                         for (j = 0; j < irn_arity;  j++) {
 721                                 ir_node *pred = get_irn_n(end, j);
 722                                 tmp_dom_info *u;
 723
 724                                 if (is_no_Block(pred) || get_Block_dom_pre_num(pred) == -1)
 725                                         continue;       /* control-dead */
 726
 727                                 u = dom_eval (&tdi_list[get_Block_dom_pre_num(pred)]);
 728                                 if (u->semi < w->semi) w->semi = u->semi;
 729                         }
 730                 }
 731
 732                 /* Add w to w->semi's bucket.  w is in exactly one bucket, so
 733                    buckets can been implemented as linked lists. */
 734                 w->bucket = w->semi->bucket;
 735                 w->semi->bucket = w;
 736
 737                 dom_link (w->parent, w);
 738
 739                 /* Step 3 */
 740                 while (w->parent->bucket) {
 741                         tmp_dom_info *u;
 742                         v = w->parent->bucket;
 743                         /* remove v from w->parent->bucket */
 744                         w->parent->bucket = v->bucket;
 745                         v->bucket = NULL;
 746
 747                         u = dom_eval (v);
 748                         if (u->semi < v->semi)
 749                                 v->dom = u;
 750                         else
 751                                 v->dom = w->parent;
 752                 }
 753         }
 754         /* Step 4 */
 755         tdi_list[0].dom = NULL;
 756         set_Block_idom(tdi_list[0].block, NULL);
 757         set_Block_dom_depth(tdi_list[0].block, 1);
 758         for (i = 1; i < n_blocks;  i++) {
 759                 tmp_dom_info *w = &tdi_list[i];
 760                 int depth;
 761
 762                 if (! w->dom)
 763                         continue; /* control dead */
 764
 765                 if (w->dom != w->semi) w->dom = w->dom->dom;
 766                 set_Block_idom(w->block, w->dom->block);
 767
 768                 /* blocks dominated by dead one's are still dead */
 769                 depth = get_Block_dom_depth(w->dom->block);
 770                 if (depth > 0)
 771                         ++depth;
 772                 set_Block_dom_depth(w->block, depth);
 773         }
 774
 775         /* clean up */
 776         free(tdi_list);
 777
 778         /* Do a walk over the tree and assign the tree pre orders. */
 779         {
 780                 unsigned tree_pre_order = 0;
 781                 dom_tree_walk_irg(irg, assign_tree_dom_pre_order,
 782                         assign_tree_dom_pre_order_max, &tree_pre_order);
 783         }
 784         current_ir_graph = rem;
 785 }
 786
 787 void assure_doms(ir_graph *irg) {
 788         if (get_irg_dom_state(irg) != dom_consistent)
 789                 compute_doms(irg);
 790 }
 791
 792 void free_dom(ir_graph *irg) {
 793         /* Update graph state */
 794         assert(get_irg_phase_state(irg) != phase_building);
 795         irg->dom_state = dom_none;
 796
 797         /* With the implementation right now there is nothing to free,
 798            but better call it anyways... */
 799 }
 800
 801 /* Computes the post dominator trees.  Sets a flag in irg to "dom_consistent".
 802    If the control flow of the graph is changed this flag must be set to
 803    "dom_inconsistent".  */
 804 void compute_postdoms(ir_graph *irg) {
 805         ir_graph *rem = current_ir_graph;
 806         int n_blocks, used, i, j;
 807         tmp_dom_info *tdi_list;
 808
 809         current_ir_graph = irg;
 810
 811         /* Update graph state */
 812         assert(get_irg_phase_state(irg) != phase_building);
 813         irg->pdom_state = dom_consistent;
 814
 815         /* Count the number of blocks in the graph. */
 816         n_blocks = init_construction(irg, count_and_init_blocks_pdom);
 817
 818         /* Memory for temporary information. */
 819         tdi_list = XMALLOCNZ(tmp_dom_info, n_blocks);
 820
 821         /* We need the out data structure. */
 822         assure_irg_outs(irg);
 823
 824         /* this with a standard walker as passing the parent to the sons isn't
 825            simple. */
 826         used = 0;
 827         inc_irg_block_visited(irg);
 828         init_tmp_pdom_info(get_irg_end_block(irg), NULL, tdi_list, &used, n_blocks);
 829         /* If not all blocks are reachable from End by cfg edges this assertion
 830            fails.
 831            assert(used == n_blocks && "Precondition for dom construction violated"); */
 832         n_blocks = used;
 833
 834
 835         for (i = n_blocks-1; i > 0; i--) {  /* Don't iterate the root, it's done. */
 836                 int irn_arity;
 837                 tmp_dom_info *w = &tdi_list[i];
 838                 tmp_dom_info *v;
 839
 840                 /* Step 2 */
 841                 irn_arity = get_Block_n_cfg_outs_ka(w->block);
 842                 for (j = 0;  j < irn_arity;  j++) {
 843                         ir_node *succ = get_Block_cfg_out_ka(w->block, j);
 844                         tmp_dom_info *u;
 845
 846                         if (get_Block_postdom_pre_num (succ) == -1)
 847                                 continue;       /* endless-loop */
 848
 849                         u = dom_eval (&tdi_list[get_Block_postdom_pre_num(succ)]);
 850                         if (u->semi < w->semi) w->semi = u->semi;
 851                 }
 852                 /* Add w to w->semi's bucket.  w is in exactly one bucket, so
 853                    buckets can be implemented as linked lists. */
 854                 w->bucket = w->semi->bucket;
 855                 w->semi->bucket = w;
 856
 857                 dom_link (w->parent, w);
 858
 859                 /* Step 3 */
 860                 while (w->parent->bucket) {
 861                         tmp_dom_info *u;
 862                         v = w->parent->bucket;
 863                         /* remove v from w->parent->bucket */
 864                         w->parent->bucket = v->bucket;
 865                         v->bucket = NULL;
 866
 867                         u = dom_eval(v);
 868                         if (u->semi < v->semi)
 869                                 v->dom = u;
 870                         else
 871                                 v->dom = w->parent;
 872                 }
 873         }
 874         /* Step 4 */
 875         tdi_list[0].dom = NULL;
 876         set_Block_ipostdom(tdi_list[0].block, NULL);
 877         set_Block_postdom_depth(tdi_list[0].block, 1);
 878         for (i = 1;  i < n_blocks;  i++) {
 879                 tmp_dom_info *w = &tdi_list[i];
 880
 881                 if (w->dom != w->semi) w->dom = w->dom->dom;
 882                 set_Block_ipostdom(w->block, w->dom->block);
 883                 set_Block_postdom_depth(w->block, get_Block_postdom_depth(w->dom->block) + 1);
 884         }
 885
 886         /* clean up */
 887         free(tdi_list);
 888
 889         /* Do a walk over the tree and assign the tree pre orders. */
 890         {
 891                 unsigned tree_pre_order = 0;
 892                 postdom_tree_walk_irg(irg, assign_tree_postdom_pre_order,
 893                         assign_tree_postdom_pre_order_max, &tree_pre_order);
 894         }
 895         current_ir_graph = rem;
 896 }
 897
 898 void assure_postdoms(ir_graph *irg) {
 899         if (get_irg_postdom_state(irg) != dom_consistent)
 900                 compute_postdoms(irg);
 901 }
 902
 903 void free_postdom(ir_graph *irg) {
 904         /* Update graph state */
 905         assert(get_irg_phase_state(irg) != phase_building);
 906         irg->pdom_state = dom_none;
 907
 908         /* With the implementation right now there is nothing to free,
 909            but better call it anyways... */
 910 }