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"
  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 {
  52         assert(is_Block(bl));
  53         if (get_Block_dom_depth(bl) == -1) {
  54                 /* This block is not reachable from Start */
  55                 return new_Bad();
  56         }
  57         return get_dom_info(bl)->idom;
  58 }
  59
  60 void set_Block_idom(ir_node *bl, ir_node *n)
  61 {
  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 {
  83         assert(is_Block(bl));
  84         if (get_Block_postdom_depth(bl) == -1) {
  85                 /* This block is not reachable from Start */
  86                 return new_Bad();
  87         }
  88         return get_pdom_info(bl)->idom;
  89 }
  90
  91 void set_Block_ipostdom(ir_node *bl, ir_node *n)
  92 {
  93         ir_dom_info *bli = get_pdom_info(bl);
  94
  95         assert(is_Block(bl));
  96
  97         /* Set the immediate post dominator of bl to n */
  98         bli->idom = n;
  99
 100         /*
 101          * If we don't set the root of the post dominator tree
 102          * Append bl to the post dominates queue of n.
 103          */
 104         if (n != NULL) {
 105                 ir_dom_info *ni = get_pdom_info(n);
 106
 107                 bli->next = ni->first;
 108                 ni->first = bl;
 109         }
 110 }
 111
 112 int get_Block_dom_pre_num(const ir_node *bl)
 113 {
 114         assert(is_Block(bl));
 115         return get_dom_info(bl)->pre_num;
 116 }
 117
 118 void set_Block_dom_pre_num(ir_node *bl, int num)
 119 {
 120         assert(is_Block(bl));
 121         get_dom_info(bl)->pre_num = num;
 122 }
 123
 124 int get_Block_dom_depth(const ir_node *bl)
 125 {
 126         assert(is_Block(bl));
 127         return get_dom_info(bl)->dom_depth;
 128 }
 129
 130 void set_Block_dom_depth(ir_node *bl, int depth)
 131 {
 132         assert(is_Block(bl));
 133         get_dom_info(bl)->dom_depth = depth;
 134 }
 135
 136
 137 int get_Block_postdom_pre_num(const ir_node *bl)
 138 {
 139         assert(is_Block(bl));
 140         return get_pdom_info(bl)->pre_num;
 141 }
 142
 143 void set_Block_postdom_pre_num(ir_node *bl, int num)
 144 {
 145         assert(is_Block(bl));
 146         get_pdom_info(bl)->pre_num = num;
 147 }
 148
 149 int get_Block_postdom_depth(const ir_node *bl)
 150 {
 151         assert(is_Block(bl));
 152         return get_pdom_info(bl)->dom_depth;
 153 }
 154
 155 void set_Block_postdom_depth(ir_node *bl, int depth)
 156 {
 157         assert(is_Block(bl));
 158         get_pdom_info(bl)->dom_depth = depth;
 159 }
 160
 161 unsigned get_Block_dom_tree_pre_num(const ir_node *bl)
 162 {
 163         assert(is_Block(bl));
 164         return get_dom_info(bl)->tree_pre_num;
 165 }
 166
 167 unsigned get_Block_dom_max_subtree_pre_num(const ir_node *bl)
 168 {
 169         assert(is_Block(bl));
 170         return get_dom_info(bl)->max_subtree_pre_num;
 171 }
 172
 173 unsigned get_Block_pdom_tree_pre_num(const ir_node *bl)
 174 {
 175         assert(is_Block(bl));
 176         return get_pdom_info(bl)->tree_pre_num;
 177 }
 178
 179 unsigned get_Block_pdom_max_subtree_pre_num(const ir_node *bl)
 180 {
 181         assert(is_Block(bl));
 182         return get_pdom_info(bl)->max_subtree_pre_num;
 183 }
 184
 185 /* Check, if a block dominates another block. */
 186 int block_dominates(const ir_node *a, const ir_node *b)
 187 {
 188         const ir_dom_info *ai, *bi;
 189
 190         if (is_Block(a) && is_Block(b)) {
 191                 ai = get_dom_info(a);
 192                 bi = get_dom_info(b);
 193                 return bi->tree_pre_num - ai->tree_pre_num
 194                         <= ai->max_subtree_pre_num - ai->tree_pre_num;
 195         }
 196
 197         return 0;
 198 }
 199
 200 /* Check, if a block strictly dominates another block. */
 201 int block_strictly_dominates(const ir_node *a, const ir_node *b)
 202 {
 203         return (a != b) && block_dominates(a, b);
 204 }
 205
 206 /* Returns the smallest common dominator block of two nodes. */
 207 ir_node *node_smallest_common_dominator(ir_node *a, ir_node *b)
 208 {
 209         ir_node *bl_a   = is_Block(a) ? a : get_nodes_block(a);
 210         ir_node *bl_b   = is_Block(b) ? b : get_nodes_block(b);
 211         ir_node *dom_bl = NULL;
 212
 213         /* Check if block of a dominates block of b */
 214         if (block_dominates(bl_a, bl_b))
 215                 dom_bl = bl_a;
 216         /* Check if block of b dominates block of a */
 217         else if (block_dominates(bl_b, bl_a))
 218                 dom_bl = bl_b;
 219         else {
 220                 /* walk up dominator tree and search for first block dominating a and b */
 221                 while (! dom_bl) {
 222                         bl_a = get_Block_idom(bl_a);
 223
 224                         assert(! is_Bad(bl_a) && "block is dead?");
 225
 226                         if (block_dominates(bl_a, bl_b))
 227                                 dom_bl = bl_a;
 228                 }
 229         }
 230
 231         return dom_bl;
 232 }
 233
 234 /* Returns the smallest common dominator block of all users of a node. */
 235 ir_node *node_users_smallest_common_dominator(ir_node *irn, int handle_phi)
 236 {
 237         int n, j, i = 0, success;
 238         ir_node **user_blocks, *dom_bl;
 239         const ir_edge_t *edge;
 240
 241         assert(! is_Block(irn) && "WRONG USAGE of node_users_smallest_common_dominator");
 242         assert(edges_activated(get_irn_irg(irn)) && "need edges activated");
 243
 244         n = get_irn_n_edges(irn);
 245
 246         /* get array to hold all block of the node users */
 247         NEW_ARR_A(ir_node *, user_blocks, n);
 248         foreach_out_edge(irn, edge) {
 249                 ir_node *src = get_edge_src_irn(edge);
 250
 251                 if (is_Phi(src) && handle_phi) {
 252                         /* get the corresponding cfg predecessor block if phi handling requested */
 253                         j  = get_edge_src_pos(edge);
 254                         assert(j >= 0 && "kaputt");
 255                         user_blocks[i++] = get_Block_cfgpred_block(get_nodes_block(src), j);
 256                 }
 257                 else
 258                         user_blocks[i++] = is_Block(src) ? src : get_nodes_block(src);
 259         }
 260
 261         assert(i == n && "get_irn_n_edges probably broken");
 262
 263         /* in case of only one user: return the block of the user */
 264         if (n == 1)
 265                 return user_blocks[0];
 266
 267         i = 0;
 268         /* search the smallest block dominating all user blocks */
 269         do {
 270                 dom_bl  = node_smallest_common_dominator(user_blocks[i], user_blocks[i + 1]);
 271                 success = 1;
 272
 273                 /* check if this block dominates all remaining blocks as well */
 274                 for (j = i + 2; j < n; j++) {
 275                         if (! block_dominates(dom_bl, user_blocks[j]))
 276                                 success = 0;
 277                 }
 278
 279                 if (success)
 280                         break;
 281
 282                 /* inherit the dominator block of the first (i + 1) users */
 283                 user_blocks[++i] = dom_bl;
 284         } while (i < n - 1);
 285
 286         assert(success && "no block found dominating all users");
 287
 288         return dom_bl;
 289 }
 290
 291
 292 /* Get the first node in the list of nodes dominated by a given block. */
 293 ir_node *get_Block_dominated_first(const ir_node *bl)
 294 {
 295         assert(is_Block(bl));
 296         return get_dom_info(bl)->first;
 297 }
 298
 299 /* Get the next node in a list of nodes which are dominated by some
 300  * other node. */
 301 ir_node *get_Block_dominated_next(const ir_node *bl)
 302 {
 303         assert(is_Block(bl));
 304         return get_dom_info(bl)->next;
 305 }
 306
 307 /* Check, if a block post dominates another block. */
 308 int block_postdominates(const ir_node *a, const ir_node *b)
 309 {
 310         const ir_dom_info *ai, *bi;
 311
 312         if (is_Block(a) && is_Block(b)) {
 313                 ai = get_pdom_info(a);
 314                 bi = get_pdom_info(b);
 315                 return bi->tree_pre_num - ai->tree_pre_num
 316                         <= ai->max_subtree_pre_num - ai->tree_pre_num;
 317         }
 318
 319         return 0;
 320 }
 321
 322 /* Check, if a block strictly dominates another block. */
 323 int block_strictly_postdominates(const ir_node *a, const ir_node *b)
 324 {
 325         return (a != b) && block_postdominates(a, b);
 326 }
 327
 328
 329 /* Get the first node in the list of nodes post dominated by a given block. */
 330 ir_node *get_Block_postdominated_first(const ir_node *bl)
 331 {
 332         assert(is_Block(bl));
 333         return get_pdom_info(bl)->first;
 334 }
 335
 336 /* Get the next node in a list of nodes which are post dominated by some
 337  * other node. */
 338 ir_node *get_Block_postdominated_next(const ir_node *bl)
 339 {
 340         assert(is_Block(bl));
 341         return get_pdom_info(bl)->next;
 342 }
 343
 344 /* Visit all nodes in the dominator subtree of a given node. */
 345 void dom_tree_walk(ir_node *bl, irg_walk_func *pre,
 346                 irg_walk_func *post, void *env)
 347 {
 348         ir_node *p;
 349
 350         if (pre)
 351                 pre(bl, env);
 352
 353         dominates_for_each(bl, p) {
 354                 dom_tree_walk(p, pre, post, env);
 355         }
 356
 357         if (post)
 358                 post(bl, env);
 359 }
 360
 361 /* Visit all nodes in the post dominator subtree of a given node. */
 362 void postdom_tree_walk(ir_node *bl, irg_walk_func *pre,
 363                 irg_walk_func *post, void *env)
 364 {
 365         ir_node *p;
 366
 367         if (pre)
 368                 pre(bl, env);
 369
 370         postdominates_for_each(bl, p) {
 371                 postdom_tree_walk(p, pre, post, env);
 372         }
 373
 374         if (post)
 375                 post(bl, env);
 376 }
 377
 378 /* Walk over the dominator tree of an irg starting at the root. */
 379 void dom_tree_walk_irg(ir_graph *irg, irg_walk_func *pre,
 380                 irg_walk_func *post, void *env)
 381 {
 382         /* The root of the dominator tree should be the Start block. */
 383         ir_node *root = get_irg_start_block(irg);
 384
 385         assert(irg->dom_state == dom_consistent
 386                         && "The dominators of the irg must be consistent");
 387         assert(root && "The start block of the graph is NULL?");
 388         assert(get_dom_info(root)->idom == NULL
 389                         && "The start node in the graph must be the root of the dominator tree");
 390         dom_tree_walk(root, pre, post, env);
 391 }
 392
 393 /* Walk over the post dominator tree of an irg starting at the root. */
 394 void postdom_tree_walk_irg(ir_graph *irg, irg_walk_func *pre,
 395                 irg_walk_func *post, void *env)
 396 {
 397         /* The root of the dominator tree should be the End block. */
 398         ir_node *root = get_irg_end_block(irg);
 399
 400         assert(irg->pdom_state == dom_consistent
 401                         && "The dominators of the irg must be consistent");
 402         assert(root && "The end block of the graph is NULL?");
 403         assert(get_pdom_info(root)->idom == NULL
 404                         && "The End block node in the graph must be the root of the post dominator tree");
 405         postdom_tree_walk(root, pre, post, env);
 406 }
 407
 408
 409 static void assign_tree_dom_pre_order(ir_node *bl, void *data)
 410 {
 411         unsigned *num = data;
 412         ir_dom_info *bi = get_dom_info(bl);
 413
 414         bi->tree_pre_num = (*num)++;
 415 }
 416
 417 static void assign_tree_dom_pre_order_max(ir_node *bl, void *data)
 418 {
 419         ir_dom_info *bi = get_dom_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_dom_info(p)->next) {
 426                 unsigned max_p = get_dom_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 static void assign_tree_postdom_pre_order(ir_node *bl, void *data)
 436 {
 437         unsigned *num = data;
 438         ir_dom_info *bi = get_pdom_info(bl);
 439
 440         bi->tree_pre_num = (*num)++;
 441 }
 442
 443 static void assign_tree_postdom_pre_order_max(ir_node *bl, void *data)
 444 {
 445         ir_dom_info *bi = get_pdom_info(bl);
 446         ir_node *p;
 447         unsigned max = 0;
 448         unsigned children = 0;
 449         (void) data;
 450
 451         for (p = bi->first; p; p = get_pdom_info(p)->next) {
 452                 unsigned max_p = get_pdom_info(p)->max_subtree_pre_num;
 453                 max = max > max_p ? max : max_p;
 454                 children++;
 455         }
 456
 457         bi->max_subtree_pre_num = children > 0 ? max : bi->tree_pre_num;
 458         assert(bi->max_subtree_pre_num >= bi->tree_pre_num);
 459 }
 460
 461 /*--------------------------------------------------------------------*/
 462 /*  Building and Removing the dominator data structure                */
 463 /*--------------------------------------------------------------------*/
 464
 465 /**
 466  * count the number of blocks and clears the post dominance info
 467  */
 468 static void count_and_init_blocks_pdom(ir_node *bl, void *env)
 469 {
 470         int *n_blocks = (int *) env;
 471         (*n_blocks) ++;
 472
 473         memset(get_pdom_info(bl), 0, sizeof(ir_dom_info));
 474         set_Block_ipostdom(bl, NULL);
 475         set_Block_postdom_pre_num(bl, -1);
 476         set_Block_postdom_depth(bl, -1);
 477 }
 478
 479 /** temporary type used while constructing the dominator / post dominator tree. */
 480 typedef struct tmp_dom_info {
 481         ir_node *block;               /**< backlink */
 482
 483         struct tmp_dom_info *semi;    /**< semidominator */
 484         struct tmp_dom_info *parent;
 485         struct tmp_dom_info *label;   /**< used for LINK and EVAL */
 486         struct tmp_dom_info *ancestor;/**< used for LINK and EVAL */
 487         struct tmp_dom_info *dom;     /**< After step 3, if the semidominator of w is
 488                                            its immediate dominator, then w->dom is the
 489                                            immediate dominator of w.  Otherwise w->dom
 490                                            is a vertex v whose number is smaller than
 491                                            w and whose immediate dominator is also w's
 492                                            immediate dominator. After step 4, w->dom
 493                                            is the immediate dominator of w.  */
 494         struct tmp_dom_info *bucket;  /**< set of vertices with same semidominator */
 495 } tmp_dom_info;
 496
 497 /** Struct to pass info through walker. */
 498 typedef struct {
 499         tmp_dom_info *d;
 500         int used;
 501 } dom_env;
 502
 503
 504 /**
 505  * Walks Blocks along the out data structure.  If recursion started with
 506  * Start block misses control dead blocks.
 507  */
 508 static void init_tmp_dom_info(ir_node *bl, tmp_dom_info *parent,
 509                               tmp_dom_info *tdi_list, int *used, int n_blocks)
 510 {
 511         tmp_dom_info *tdi;
 512         int i;
 513
 514         assert(is_Block(bl));
 515         if (get_irg_block_visited(current_ir_graph) == get_Block_block_visited(bl))
 516           return;
 517         mark_Block_block_visited(bl);
 518         set_Block_dom_pre_num(bl, *used);
 519
 520         assert(*used < n_blocks);
 521         tdi = &tdi_list[*used];
 522         ++(*used);
 523
 524         tdi->semi     = tdi;
 525         tdi->label    = tdi;
 526         tdi->ancestor = NULL;
 527         tdi->bucket   = NULL;
 528         tdi->parent   = parent;
 529         tdi->block    = bl;
 530
 531         /* Iterate */
 532         for (i = get_Block_n_cfg_outs_ka(bl) - 1; i >= 0; --i) {
 533                 ir_node *pred = get_Block_cfg_out_ka(bl, i);
 534                 /* can happen for half-optimized dead code (I've seen this in student
 535                    projects */
 536                 if (!is_Block(pred))
 537                         continue;
 538
 539                 init_tmp_dom_info(pred, tdi, tdi_list, used, n_blocks);
 540         }
 541 }
 542
 543 /**
 544  * Walks Blocks along the control flow.  If recursion started with
 545  * End block misses blocks in endless loops.
 546  */
 547 static void init_tmp_pdom_info(ir_node *bl, tmp_dom_info *parent,
 548                                tmp_dom_info *tdi_list, int* used, int n_blocks)
 549 {
 550         tmp_dom_info *tdi;
 551         int i;
 552
 553         assert(is_Block(bl));
 554         if (get_irg_block_visited(current_ir_graph) == get_Block_block_visited(bl))
 555           return;
 556         mark_Block_block_visited(bl);
 557         set_Block_postdom_pre_num(bl, *used);
 558
 559         assert(*used < n_blocks);
 560         tdi = &tdi_list[*used];
 561         ++(*used);
 562
 563         tdi->semi = tdi;
 564         tdi->label = tdi;
 565         tdi->ancestor = NULL;
 566         tdi->bucket = NULL;
 567         tdi->parent = parent;
 568         tdi->block = bl;
 569
 570         /* Iterate */
 571         for (i = get_Block_n_cfgpreds(bl) - 1; i >= 0; --i) {
 572                 ir_node *pred = get_Block_cfgpred_block(bl, i);
 573                 if (is_Bad(pred))
 574                         continue;
 575                 assert(is_Block(pred));
 576                 init_tmp_pdom_info(pred, tdi, tdi_list, used, n_blocks);
 577         }
 578
 579         /* Handle keep-alives. Note that the preprocessing
 580            in init_construction() had already killed all
 581            phantom keep-alive edges. All remaining block keep-alives
 582            are really edges to endless loops.
 583          */
 584         if (bl == get_irg_end_block(current_ir_graph)) {
 585                 ir_node *end = get_irg_end(current_ir_graph);
 586
 587                 for (i = get_irn_arity(end) - 1; i >= 0; --i) {
 588                         ir_node *pred = get_irn_n(end, i);
 589
 590                         if (is_Block(pred))
 591                                 init_tmp_pdom_info(pred, tdi, tdi_list, used, n_blocks);
 592                 }
 593         }
 594 }
 595
 596 static void dom_compress(tmp_dom_info *v)
 597 {
 598         assert (v->ancestor);
 599         if (v->ancestor->ancestor) {
 600                 dom_compress (v->ancestor);
 601                 if (v->ancestor->label->semi < v->label->semi) {
 602                         v->label = v->ancestor->label;
 603                 }
 604                 v->ancestor = v->ancestor->ancestor;
 605         }
 606 }
 607
 608 /**
 609  * if V is a root, return v, else return the vertex u, not being the
 610  * root, with minimum u->semi on the path from v to its root.
 611  */
 612 inline static tmp_dom_info *dom_eval(tmp_dom_info *v)
 613 {
 614         if (!v->ancestor) return v;
 615         dom_compress (v);
 616         return v->label;
 617 }
 618
 619 /** make V W's ancestor */
 620 inline static void dom_link(tmp_dom_info *v, tmp_dom_info *w)
 621 {
 622         w->ancestor = v;
 623 }
 624
 625 /**
 626  * Walker: count the number of blocks and clears the dominance info
 627  */
 628 static void count_and_init_blocks_dom(ir_node *bl, void *env)
 629 {
 630         int *n_blocks = (int *) env;
 631         (*n_blocks) ++;
 632
 633         memset(get_dom_info(bl), 0, sizeof(ir_dom_info));
 634         set_Block_idom(bl, NULL);
 635         set_Block_dom_pre_num(bl, -1);
 636         set_Block_dom_depth(bl, -1);
 637 }
 638
 639 /**
 640  * Initialize the dominance/postdominance construction:
 641  *
 642  * - count the number of blocks
 643  * - clear the dominance info
 644  * - remove Block-keepalives of live blocks to reduce
 645  *   the number of "phantom" block edges
 646  *
 647  * @param irg  the graph
 648  * @param pre  a walker function that will be called for every block in the graph
 649  */
 650 static int init_construction(ir_graph *irg, irg_walk_func *pre)
 651 {
 652         ir_graph *rem = current_ir_graph;
 653         ir_node *end;
 654         int arity;
 655         int n_blocks = 0;
 656
 657         current_ir_graph = irg;
 658
 659         /* this visits only the reachable blocks */
 660         irg_block_walk(get_irg_end_block(irg), pre, NULL, &n_blocks);
 661
 662         /* now visit the unreachable (from End) Blocks and remove unnecessary keep-alives */
 663         end   = get_irg_end(irg);
 664         arity = get_End_n_keepalives(end);
 665         if (arity) {    /* we have keep-alives */
 666                 ir_node **in;
 667                 int i, j;
 668
 669                 NEW_ARR_A(ir_node *, in, arity);
 670                 for (i = j = 0; i < arity; i++) {
 671                         ir_node *pred = get_End_keepalive(end, i);
 672
 673                         if (!is_Block(pred)) {
 674                                 pred = get_nodes_block(pred);
 675                                 if (!is_Block(pred)) {
 676                                         /* a node which has a bad block input: kill it */
 677                                         continue;
 678                                 }
 679                         }
 680                         dec_irg_block_visited(irg);
 681                         irg_block_walk(pred, pre, NULL, &n_blocks);
 682                         in[j++] = pred;
 683                 }
 684                 if (j != arity) {
 685                         /* we kill some keep-alives */
 686                         set_End_keepalives(end, j, in);
 687                         set_irg_outs_inconsistent(irg);
 688                 }
 689         }
 690
 691         current_ir_graph = rem;
 692         return n_blocks;
 693 }
 694
 695
 696 /* Computes the dominator trees.  Sets a flag in irg to "dom_consistent".
 697    If the control flow of the graph is changed this flag must be set to
 698    "dom_inconsistent".  */
 699 void compute_doms(ir_graph *irg)
 700 {
 701         ir_graph *rem = current_ir_graph;
 702         int n_blocks, used, i, j;
 703         tmp_dom_info *tdi_list;   /* Ein Golf? */
 704
 705         current_ir_graph = irg;
 706
 707         /* Update graph state */
 708         assert(get_irg_phase_state(irg) != phase_building);
 709         irg->dom_state = dom_consistent;
 710
 711         /* Count the number of blocks in the graph. */
 712         n_blocks = init_construction(irg, count_and_init_blocks_dom);
 713
 714         /* Memory for temporary information. */
 715         tdi_list = XMALLOCNZ(tmp_dom_info, n_blocks);
 716
 717         /* We need the out data structure. */
 718         assure_irg_outs(irg);
 719
 720         /* this with a standard walker as passing the parent to the sons isn't
 721            simple. */
 722         used = 0;
 723         inc_irg_block_visited(irg);
 724         init_tmp_dom_info(get_irg_start_block(irg), NULL, tdi_list, &used, n_blocks);
 725         /* If not all blocks are reachable from Start by out edges this assertion
 726            fails.
 727            assert(used == n_blocks && "Precondition for dom construction violated"); */
 728         assert(used <= n_blocks && "Precondition for dom construction violated");
 729         n_blocks = used;
 730
 731
 732         for (i = n_blocks-1; i > 0; i--) {  /* Don't iterate the root, it's done. */
 733                 int irn_arity;
 734                 tmp_dom_info *w = &tdi_list[i];
 735                 tmp_dom_info *v;
 736
 737                 /* Step 2 */
 738                 irn_arity = get_irn_arity(w->block);
 739                 for (j = 0; j < irn_arity;  j++) {
 740                         ir_node *pred = get_Block_cfgpred_block(w->block, j);
 741                         tmp_dom_info *u;
 742
 743                         if (is_Bad(pred) || (get_Block_dom_pre_num (pred) == -1))
 744                                 continue;       /* control-dead */
 745
 746                         u = dom_eval (&tdi_list[get_Block_dom_pre_num(pred)]);
 747                         if (u->semi < w->semi) w->semi = u->semi;
 748                 }
 749
 750                 /* handle keep-alives if we are at the end block */
 751                 if (w->block == get_irg_end_block(irg)) {
 752                         ir_node *end = get_irg_end(irg);
 753
 754                         irn_arity = get_irn_arity(end);
 755                         for (j = 0; j < irn_arity;  j++) {
 756                                 ir_node *pred = get_irn_n(end, j);
 757                                 tmp_dom_info *u;
 758
 759                                 if (is_no_Block(pred) || get_Block_dom_pre_num(pred) == -1)
 760                                         continue;       /* control-dead */
 761
 762                                 u = dom_eval (&tdi_list[get_Block_dom_pre_num(pred)]);
 763                                 if (u->semi < w->semi) w->semi = u->semi;
 764                         }
 765                 }
 766
 767                 /* Add w to w->semi's bucket.  w is in exactly one bucket, so
 768                    buckets can been implemented as linked lists. */
 769                 w->bucket = w->semi->bucket;
 770                 w->semi->bucket = w;
 771
 772                 dom_link (w->parent, w);
 773
 774                 /* Step 3 */
 775                 while (w->parent->bucket) {
 776                         tmp_dom_info *u;
 777                         v = w->parent->bucket;
 778                         /* remove v from w->parent->bucket */
 779                         w->parent->bucket = v->bucket;
 780                         v->bucket = NULL;
 781
 782                         u = dom_eval (v);
 783                         if (u->semi < v->semi)
 784                                 v->dom = u;
 785                         else
 786                                 v->dom = w->parent;
 787                 }
 788         }
 789         /* Step 4 */
 790         tdi_list[0].dom = NULL;
 791         set_Block_idom(tdi_list[0].block, NULL);
 792         set_Block_dom_depth(tdi_list[0].block, 1);
 793         for (i = 1; i < n_blocks;  i++) {
 794                 tmp_dom_info *w = &tdi_list[i];
 795                 int depth;
 796
 797                 if (! w->dom)
 798                         continue; /* control dead */
 799
 800                 if (w->dom != w->semi) w->dom = w->dom->dom;
 801                 set_Block_idom(w->block, w->dom->block);
 802
 803                 /* blocks dominated by dead one's are still dead */
 804                 depth = get_Block_dom_depth(w->dom->block);
 805                 if (depth > 0)
 806                         ++depth;
 807                 set_Block_dom_depth(w->block, depth);
 808         }
 809
 810         /* clean up */
 811         free(tdi_list);
 812
 813         /* Do a walk over the tree and assign the tree pre orders. */
 814         {
 815                 unsigned tree_pre_order = 0;
 816                 dom_tree_walk_irg(irg, assign_tree_dom_pre_order,
 817                         assign_tree_dom_pre_order_max, &tree_pre_order);
 818         }
 819         current_ir_graph = rem;
 820 }
 821
 822 void assure_doms(ir_graph *irg)
 823 {
 824         if (get_irg_dom_state(irg) != dom_consistent)
 825                 compute_doms(irg);
 826 }
 827
 828 void free_dom(ir_graph *irg)
 829 {
 830         /* Update graph state */
 831         assert(get_irg_phase_state(irg) != phase_building);
 832         irg->dom_state = dom_none;
 833
 834         /* With the implementation right now there is nothing to free,
 835            but better call it anyways... */
 836 }
 837
 838 /* Computes the post dominator trees.  Sets a flag in irg to "dom_consistent".
 839    If the control flow of the graph is changed this flag must be set to
 840    "dom_inconsistent".  */
 841 void compute_postdoms(ir_graph *irg)
 842 {
 843         ir_graph *rem = current_ir_graph;
 844         int n_blocks, used, i, j;
 845         tmp_dom_info *tdi_list;
 846
 847         current_ir_graph = irg;
 848
 849         /* Update graph state */
 850         assert(get_irg_phase_state(irg) != phase_building);
 851         irg->pdom_state = dom_consistent;
 852
 853         /* Count the number of blocks in the graph. */
 854         n_blocks = init_construction(irg, count_and_init_blocks_pdom);
 855
 856         /* Memory for temporary information. */
 857         tdi_list = XMALLOCNZ(tmp_dom_info, n_blocks);
 858
 859         /* We need the out data structure. */
 860         assure_irg_outs(irg);
 861
 862         /* this with a standard walker as passing the parent to the sons isn't
 863            simple. */
 864         used = 0;
 865         inc_irg_block_visited(irg);
 866         init_tmp_pdom_info(get_irg_end_block(irg), NULL, tdi_list, &used, n_blocks);
 867         /* If not all blocks are reachable from End by cfg edges this assertion
 868            fails.
 869            assert(used == n_blocks && "Precondition for dom construction violated"); */
 870         n_blocks = used;
 871
 872
 873         for (i = n_blocks-1; i > 0; i--) {  /* Don't iterate the root, it's done. */
 874                 int irn_arity;
 875                 tmp_dom_info *w = &tdi_list[i];
 876                 tmp_dom_info *v;
 877
 878                 /* Step 2 */
 879                 irn_arity = get_Block_n_cfg_outs_ka(w->block);
 880                 for (j = 0;  j < irn_arity;  j++) {
 881                         ir_node *succ = get_Block_cfg_out_ka(w->block, j);
 882                         tmp_dom_info *u;
 883
 884                         if (get_Block_postdom_pre_num (succ) == -1)
 885                                 continue;       /* endless-loop */
 886
 887                         u = dom_eval (&tdi_list[get_Block_postdom_pre_num(succ)]);
 888                         if (u->semi < w->semi) w->semi = u->semi;
 889                 }
 890                 /* Add w to w->semi's bucket.  w is in exactly one bucket, so
 891                    buckets can be implemented as linked lists. */
 892                 w->bucket = w->semi->bucket;
 893                 w->semi->bucket = w;
 894
 895                 dom_link (w->parent, w);
 896
 897                 /* Step 3 */
 898                 while (w->parent->bucket) {
 899                         tmp_dom_info *u;
 900                         v = w->parent->bucket;
 901                         /* remove v from w->parent->bucket */
 902                         w->parent->bucket = v->bucket;
 903                         v->bucket = NULL;
 904
 905                         u = dom_eval(v);
 906                         if (u->semi < v->semi)
 907                                 v->dom = u;
 908                         else
 909                                 v->dom = w->parent;
 910                 }
 911         }
 912         /* Step 4 */
 913         tdi_list[0].dom = NULL;
 914         set_Block_ipostdom(tdi_list[0].block, NULL);
 915         set_Block_postdom_depth(tdi_list[0].block, 1);
 916         for (i = 1;  i < n_blocks;  i++) {
 917                 tmp_dom_info *w = &tdi_list[i];
 918
 919                 if (w->dom != w->semi) w->dom = w->dom->dom;
 920                 set_Block_ipostdom(w->block, w->dom->block);
 921                 set_Block_postdom_depth(w->block, get_Block_postdom_depth(w->dom->block) + 1);
 922         }
 923
 924         /* clean up */
 925         free(tdi_list);
 926
 927         /* Do a walk over the tree and assign the tree pre orders. */
 928         {
 929                 unsigned tree_pre_order = 0;
 930                 postdom_tree_walk_irg(irg, assign_tree_postdom_pre_order,
 931                         assign_tree_postdom_pre_order_max, &tree_pre_order);
 932         }
 933         current_ir_graph = rem;
 934 }
 935
 936 void assure_postdoms(ir_graph *irg)
 937 {
 938         if (get_irg_postdom_state(irg) != dom_consistent)
 939                 compute_postdoms(irg);
 940 }
 941
 942 void free_postdom(ir_graph *irg)
 943 {
 944         /* Update graph state */
 945         assert(get_irg_phase_state(irg) != phase_building);
 946         irg->pdom_state = dom_none;
 947
 948         /* With the implementation right now there is nothing to free,
 949            but better call it anyways... */
 950 }