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