nsz Git - libfirm/blob - heuristical.c

   1 #include "adt/array.h"
   2 #include "assert.h"
   3 #include "error.h"
   4
   5 #include "heuristical.h"
   6 #include "html_dumper.h"
   7 #include "kaps.h"
   8 #include "matrix.h"
   9 #include "pbqp_edge.h"
  10 #include "pbqp_edge_t.h"
  11 #include "pbqp_node.h"
  12 #include "pbqp_node_t.h"
  13 #include "vector.h"
  14
  15 static pbqp_edge **edge_bucket;
  16 static pbqp_node **node_buckets[4];
  17 static pbqp_node **reduced_bucket = NULL;
  18 static int         buckets_filled = 0;
  19
  20 static void insert_into_edge_bucket(pbqp_edge *edge)
  21 {
  22         unsigned bucket_len = ARR_LEN(edge_bucket);
  23
  24         if (edge->bucket_index < bucket_len && edge_bucket[edge->bucket_index]
  25                         == edge)
  26                 /* Edge is already inserted. */
  27                 return;
  28
  29         edge->bucket_index = bucket_len;
  30         ARR_APP1(pbqp_edge *, edge_bucket, edge);
  31 }
  32
  33 static void init_buckets(void)
  34 {
  35         int i;
  36
  37         edge_bucket = NEW_ARR_F(pbqp_edge *, 0);
  38         reduced_bucket = NEW_ARR_F(pbqp_node *, 0);
  39
  40         for (i = 0; i < 4; ++i) {
  41                 node_buckets[i] = NEW_ARR_F(pbqp_node *, 0);
  42         }
  43 }
  44
  45 static void free_buckets(void)
  46 {
  47         int i;
  48
  49         for (i = 0; i < 4; ++i) {
  50                 DEL_ARR_F(node_buckets[i]);
  51                 node_buckets[i] = NULL;
  52         }
  53
  54         DEL_ARR_F(edge_bucket);
  55         edge_bucket = NULL;
  56
  57         DEL_ARR_F(reduced_bucket);
  58         reduced_bucket = NULL;
  59
  60         buckets_filled = 0;
  61 }
  62
  63 static void fill_node_buckets(pbqp *pbqp)
  64 {
  65         unsigned node_index;
  66         unsigned node_len;
  67
  68         assert(pbqp);
  69         node_len = pbqp->num_nodes;
  70
  71         for (node_index = 0; node_index < node_len; ++node_index) {
  72                 unsigned   arity;
  73                 pbqp_node *node = get_node(pbqp, node_index);
  74
  75                 if (!node) continue;
  76
  77                 arity = ARR_LEN(node->edges);
  78
  79                 /* We have only one bucket for nodes with arity >= 3. */
  80                 if (arity > 3) {
  81                         arity = 3;
  82                 }
  83
  84                 node->bucket_index = ARR_LEN(node_buckets[arity]);
  85
  86                 ARR_APP1(pbqp_node *, node_buckets[arity], node);
  87         }
  88
  89         buckets_filled = 1;
  90 }
  91
  92 static void normalize_towards_source(pbqp *pbqp, pbqp_edge *edge)
  93 {
  94         pbqp_matrix    *mat;
  95         pbqp_node      *src_node;
  96         pbqp_node      *tgt_node;
  97         vector         *src_vec;
  98         vector         *tgt_vec;
  99         int             src_len;
 100         int             tgt_len;
 101         int             src_index;
 102
 103         assert(pbqp);
 104         assert(edge);
 105
 106         src_node = edge->src;
 107         tgt_node = edge->tgt;
 108         assert(src_node);
 109         assert(tgt_node);
 110
 111         src_vec = src_node->costs;
 112         tgt_vec = tgt_node->costs;
 113         assert(src_vec);
 114         assert(tgt_vec);
 115
 116         src_len = src_vec->len;
 117         tgt_len = tgt_vec->len;
 118         assert(src_len > 0);
 119         assert(tgt_len > 0);
 120
 121         mat = edge->costs;
 122         assert(mat);
 123
 124         /* Normalize towards source node. */
 125         for (src_index = 0; src_index < src_len; ++src_index) {
 126                 num min = pbqp_matrix_get_row_min(mat, src_index, tgt_vec);
 127
 128                 if (min != 0) {
 129                         pbqp_matrix_sub_row_value(mat, src_index, tgt_vec, min);
 130                         src_vec->entries[src_index].data = pbqp_add(
 131                                         src_vec->entries[src_index].data, min);
 132
 133                         if (min == INF_COSTS) {
 134                                 insert_into_edge_bucket(edge);
 135                         }
 136                 }
 137         }
 138 }
 139
 140 static void normalize_towards_target(pbqp *pbqp, pbqp_edge *edge)
 141 {
 142         pbqp_matrix    *mat;
 143         pbqp_node      *src_node;
 144         pbqp_node      *tgt_node;
 145         vector         *src_vec;
 146         vector         *tgt_vec;
 147         int             src_len;
 148         int             tgt_len;
 149         int             tgt_index;
 150
 151         assert(pbqp);
 152         assert(edge);
 153
 154         src_node = edge->src;
 155         tgt_node = edge->tgt;
 156         assert(src_node);
 157         assert(tgt_node);
 158
 159         src_vec = src_node->costs;
 160         tgt_vec = tgt_node->costs;
 161         assert(src_vec);
 162         assert(tgt_vec);
 163
 164         src_len = src_vec->len;
 165         tgt_len = tgt_vec->len;
 166         assert(src_len > 0);
 167         assert(tgt_len > 0);
 168
 169         mat = edge->costs;
 170         assert(mat);
 171
 172         for (tgt_index = 0; tgt_index < tgt_len; ++tgt_index) {
 173                 num min = pbqp_matrix_get_col_min(mat, tgt_index, src_vec);
 174
 175                 if (min != 0) {
 176                         pbqp_matrix_sub_col_value(mat, tgt_index, src_vec, min);
 177                         tgt_vec->entries[tgt_index].data = pbqp_add(
 178                                         tgt_vec->entries[tgt_index].data, min);
 179
 180                         if (min == INF_COSTS) {
 181                                 insert_into_edge_bucket(edge);
 182                         }
 183                 }
 184         }
 185 }
 186
 187 static void reorder_node(pbqp_node *node)
 188 {
 189         unsigned    arity;
 190         unsigned    old_arity;
 191         unsigned    old_bucket_len;
 192         unsigned    old_bucket_index;
 193         pbqp_node **old_bucket;
 194         pbqp_node  *other;
 195
 196         if (!buckets_filled) return;
 197
 198         assert(node);
 199
 200         arity = ARR_LEN(node->edges);
 201
 202         /* Same bucket as before */
 203         if (arity > 2) return;
 204
 205         /* Assume node lost one incident edge. */
 206         old_arity        = arity + 1;
 207         old_bucket       = node_buckets[old_arity];
 208         old_bucket_len   = ARR_LEN(old_bucket);
 209         old_bucket_index = node->bucket_index;
 210
 211         if (old_bucket_len <= old_bucket_index ||
 212             old_bucket[old_bucket_index] != node) {
 213                 /* Old arity is new arity, so we have nothing to do. */
 214                 assert(old_bucket_index < ARR_LEN(node_buckets[arity]) &&
 215                        node_buckets[arity][old_bucket_index] == node);
 216                 return;
 217         }
 218
 219         assert(old_bucket[old_bucket_index] == node);
 220
 221         /* Delete node from old bucket... */
 222         other                        = old_bucket[old_bucket_len - 1];
 223         other->bucket_index          = old_bucket_index;
 224         old_bucket[old_bucket_index] = other;
 225         ARR_SHRINKLEN(node_buckets[old_arity], old_bucket_len - 1);
 226
 227         /* ..and add to new one. */
 228         node->bucket_index = ARR_LEN(node_buckets[arity]);
 229         ARR_APP1(pbqp_node*, node_buckets[arity], node);
 230 }
 231
 232 static void simplify_edge(pbqp *pbqp, pbqp_edge *edge)
 233 {
 234         pbqp_matrix    *mat;
 235         pbqp_node      *src_node;
 236         pbqp_node      *tgt_node;
 237         vector         *src_vec;
 238         vector         *tgt_vec;
 239         int             src_len;
 240         int             tgt_len;
 241
 242         assert(pbqp);
 243         assert(edge);
 244
 245         src_node = edge->src;
 246         tgt_node = edge->tgt;
 247         assert(src_node);
 248         assert(tgt_node);
 249
 250         /* If edge are already deleted, we have nothing to do. */
 251         if (!is_connected(src_node, edge) || !is_connected(tgt_node, edge))
 252                 return;
 253
 254         if (pbqp->dump_file) {
 255                 char txt[100];
 256                 sprintf(txt, "Simplification of Edge n%d-n%d", src_node->index, tgt_node->index);
 257                 dump_section(pbqp->dump_file, 3, txt);
 258         }
 259
 260         src_vec = src_node->costs;
 261         tgt_vec = tgt_node->costs;
 262         assert(src_vec);
 263         assert(tgt_vec);
 264
 265         src_len = src_vec->len;
 266         tgt_len = tgt_vec->len;
 267         assert(src_len > 0);
 268         assert(tgt_len > 0);
 269
 270         mat = edge->costs;
 271         assert(mat);
 272
 273         if (pbqp->dump_file) {
 274                 fputs("Input:<br>\n", pbqp->dump_file);
 275                 dump_simplifyedge(pbqp, edge);
 276         }
 277
 278         normalize_towards_source(pbqp, edge);
 279         normalize_towards_target(pbqp, edge);
 280
 281         if (pbqp->dump_file) {
 282                 fputs("<br>\nOutput:<br>\n", pbqp->dump_file);
 283                 dump_simplifyedge(pbqp, edge);
 284         }
 285
 286         if (pbqp_matrix_is_zero(mat, src_vec, tgt_vec)) {
 287                 if (pbqp->dump_file) {
 288                         fputs("edge has been eliminated<br>\n", pbqp->dump_file);
 289                 }
 290
 291                 delete_edge(edge);
 292                 reorder_node(src_node);
 293                 reorder_node(tgt_node);
 294         }
 295 }
 296
 297 void solve_pbqp_heuristical(pbqp *pbqp)
 298 {
 299         unsigned node_index;
 300         unsigned node_len;
 301
 302         assert(pbqp);
 303
 304         if (pbqp->dump_file) {
 305                 pbqp_dump_input(pbqp);
 306                 dump_section(pbqp->dump_file, 1, "2. Simplification of Cost Matrices");
 307         }
 308
 309         node_len = pbqp->num_nodes;
 310
 311         init_buckets();
 312
 313         /* First simplify all edges. */
 314         for (node_index = 0; node_index < node_len; ++node_index) {
 315                 unsigned    edge_index;
 316                 pbqp_node  *node = get_node(pbqp, node_index);
 317                 pbqp_edge **edges;
 318                 unsigned    edge_len;
 319
 320                 if (!node) continue;
 321
 322                 edges = node->edges;
 323                 edge_len = ARR_LEN(edges);
 324
 325                 for (edge_index = 0; edge_index < edge_len; ++edge_index) {
 326                         pbqp_edge *edge = edges[edge_index];
 327
 328                         /* Simplify only once per edge. */
 329                         if (node != edge->src) continue;
 330
 331                         simplify_edge(pbqp, edge);
 332                 }
 333         }
 334
 335         /* Put node into bucket representing their arity. */
 336         fill_node_buckets(pbqp);
 337
 338         for (;;) {
 339                 if (ARR_LEN(edge_bucket) > 0) {
 340                         apply_edge(pbqp);
 341                 } else if (ARR_LEN(node_buckets[1]) > 0) {
 342                         apply_RI(pbqp);
 343                 } else if (ARR_LEN(node_buckets[2]) > 0) {
 344                         apply_RII(pbqp);
 345                 } else if (ARR_LEN(node_buckets[3]) > 0) {
 346                         panic("Please implement RN simplification");
 347                 } else {
 348                         break;
 349                 }
 350         }
 351
 352         if (pbqp->dump_file) {
 353                 dump_section(pbqp->dump_file, 1, "4. Determine Solution/Minimum");
 354                 dump_section(pbqp->dump_file, 2, "4.1. Trivial Solution");
 355         }
 356
 357         /* Solve trivial nodes and calculate solution. */
 358         node_len = ARR_LEN(node_buckets[0]);
 359         for (node_index = 0; node_index < node_len; ++node_index) {
 360                 pbqp_node *node = node_buckets[0][node_index];
 361                 assert(node);
 362
 363                 node->solution = vector_get_min_index(node->costs);
 364                 pbqp->solution = pbqp_add(pbqp->solution,
 365                                 node->costs->entries[node->solution].data);
 366                 if (pbqp->dump_file) {
 367                         fprintf(pbqp->dump_file, "node n%d is set to %d<br>\n", node->index, node->solution);
 368                         dump_node(pbqp, node);
 369                 }
 370         }
 371
 372         if (pbqp->dump_file) {
 373                 dump_section(pbqp->dump_file, 2, "Minimum");
 374                 fprintf(pbqp->dump_file, "Minimum is equal to %d.", pbqp->solution);
 375                 dump_section(pbqp->dump_file, 2, "Back Propagation");
 376         }
 377
 378         /* Solve reduced nodes. */
 379         node_len = ARR_LEN(reduced_bucket);
 380         for (node_index = node_len; node_index > 0; --node_index) {
 381                 pbqp_node *node = reduced_bucket[node_index - 1];
 382                 assert(node);
 383
 384                 switch (ARR_LEN(node->edges)) {
 385                         case 1:
 386                                 back_propagate_RI(pbqp, node);
 387                                 break;
 388                         case 2:
 389                                 back_propagate_RII(pbqp, node);
 390                                 break;
 391                         default:
 392                                 panic("Only nodes with degree one or two should be in this bucket");
 393                                 break;
 394                 }
 395         }
 396
 397         free_buckets();
 398 }
 399
 400 void apply_edge(pbqp *pbqp)
 401 {
 402         unsigned   bucket_len = ARR_LEN(edge_bucket);
 403         pbqp_edge *edge       = edge_bucket[bucket_len - 1];
 404
 405         ARR_SHRINKLEN(edge_bucket, (int)bucket_len - 1);
 406
 407         simplify_edge(pbqp, edge);
 408 }
 409
 410 void apply_RI(pbqp *pbqp)
 411 {
 412         pbqp_node  **bucket     = node_buckets[1];
 413         unsigned     bucket_len = ARR_LEN(bucket);
 414         pbqp_node   *node       = bucket[bucket_len - 1];
 415         pbqp_edge   *edge       = node->edges[0];
 416         pbqp_matrix *mat        = edge->costs;
 417         int          is_src     = edge->src == node;
 418         pbqp_node   *other_node;
 419
 420         if (is_src) {
 421                 other_node = edge->tgt;
 422         } else {
 423                 other_node = edge->src;
 424         }
 425
 426         if (pbqp->dump_file) {
 427                 char     txt[100];
 428                 sprintf(txt, "RI-Reduktion of Node n%d", node->index);
 429                 dump_section(pbqp->dump_file, 2, txt);
 430                 pbqp_dump_graph(pbqp);
 431                 fputs("<br>\nBefore reduction:<br>\n", pbqp->dump_file);
 432                 dump_node(pbqp, node);
 433                 dump_node(pbqp, other_node);
 434                 dump_edge(pbqp, edge);
 435         }
 436
 437         if (is_src) {
 438                 pbqp_matrix_add_to_all_cols(mat, node->costs);
 439                 normalize_towards_target(pbqp, edge);
 440         } else {
 441                 pbqp_matrix_add_to_all_rows(mat, node->costs);
 442                 normalize_towards_source(pbqp, edge);
 443         }
 444         disconnect_edge(other_node, edge);
 445
 446         if (pbqp->dump_file) {
 447                 fputs("<br>\nAfter reduction:<br>\n", pbqp->dump_file);
 448                 dump_node(pbqp, other_node);
 449         }
 450
 451         /* Remove node from bucket... */
 452         ARR_SHRINKLEN(bucket, (int)bucket_len - 1);
 453         reorder_node(other_node);
 454
 455         /* ...and add it to back propagation list. */
 456         node->bucket_index = ARR_LEN(reduced_bucket);
 457         ARR_APP1(pbqp_node *, reduced_bucket, node);
 458 }
 459
 460 void apply_RII(pbqp *pbqp)
 461 {
 462         pbqp_node  **bucket     = node_buckets[2];
 463         unsigned     bucket_len = ARR_LEN(bucket);
 464         pbqp_node   *node       = bucket[bucket_len - 1];
 465         pbqp_edge   *src_edge   = node->edges[0];
 466         pbqp_edge   *tgt_edge   = node->edges[1];
 467         int          src_is_src = src_edge->src == node;
 468         int          tgt_is_src = tgt_edge->src == node;
 469         pbqp_matrix *src_mat;
 470         pbqp_matrix *tgt_mat;
 471         pbqp_node   *src_node;
 472         pbqp_node   *tgt_node;
 473         pbqp_matrix *mat;
 474         vector      *vec;
 475         vector      *node_vec;
 476         vector      *src_vec;
 477         vector      *tgt_vec;
 478         unsigned     col_index;
 479         unsigned     col_len;
 480         unsigned     row_index;
 481         unsigned     row_len;
 482         unsigned     node_len;
 483
 484         assert(pbqp);
 485
 486         if (src_is_src) {
 487                 src_node = src_edge->tgt;
 488         } else {
 489                 src_node = src_edge->src;
 490         }
 491
 492         if (tgt_is_src) {
 493                 tgt_node = tgt_edge->tgt;
 494         } else {
 495                 tgt_node = tgt_edge->src;
 496         }
 497
 498         /* Swap nodes if necessary. */
 499         if (tgt_node->index < src_node->index) {
 500                 pbqp_node *tmp_node;
 501                 pbqp_edge *tmp_edge;
 502
 503                 tmp_node = src_node;
 504                 src_node = tgt_node;
 505                 tgt_node = tmp_node;
 506
 507                 tmp_edge = src_edge;
 508                 src_edge = tgt_edge;
 509                 tgt_edge = tmp_edge;
 510
 511                 src_is_src = src_edge->src == node;
 512                 tgt_is_src = tgt_edge->src == node;
 513         }
 514
 515         if (pbqp->dump_file) {
 516                 char     txt[100];
 517                 sprintf(txt, "RII-Reduktion of Node n%d", node->index);
 518                 dump_section(pbqp->dump_file, 2, txt);
 519                 pbqp_dump_graph(pbqp);
 520                 fputs("<br>\nBefore reduction:<br>\n", pbqp->dump_file);
 521                 dump_node(pbqp, src_node);
 522                 dump_edge(pbqp, src_edge);
 523                 dump_node(pbqp, node);
 524                 dump_edge(pbqp, tgt_edge);
 525                 dump_node(pbqp, tgt_node);
 526         }
 527
 528         src_mat = src_edge->costs;
 529         tgt_mat = tgt_edge->costs;
 530
 531         src_vec  = src_node->costs;
 532         tgt_vec  = tgt_node->costs;
 533         node_vec = node->costs;
 534
 535         row_len  = src_vec->len;
 536         col_len  = tgt_vec->len;
 537         node_len = node_vec->len;
 538
 539         mat = pbqp_matrix_alloc(pbqp, row_len, col_len);
 540
 541         for (row_index = 0; row_index < row_len; ++row_index) {
 542                 for (col_index = 0; col_index < col_len; ++col_index) {
 543                         vec = vector_copy(pbqp, node_vec);
 544
 545                         if (src_is_src) {
 546                                 vector_add_matrix_col(vec, src_mat, row_index);
 547                         } else {
 548                                 vector_add_matrix_row(vec, src_mat, row_index);
 549                         }
 550
 551                         if (tgt_is_src) {
 552                                 vector_add_matrix_col(vec, tgt_mat, col_index);
 553                         } else {
 554                                 vector_add_matrix_row(vec, tgt_mat, col_index);
 555                         }
 556
 557                         mat->entries[row_index * col_len + col_index] = vector_get_min(vec);
 558
 559                         obstack_free(&pbqp->obstack, vec);
 560                 }
 561         }
 562
 563         pbqp_edge *edge = get_edge(pbqp, src_node->index, tgt_node->index);
 564
 565         /* Disconnect node. */
 566         disconnect_edge(src_node, src_edge);
 567         disconnect_edge(tgt_node, tgt_edge);
 568
 569         /* Remove node from bucket... */
 570         ARR_SHRINKLEN(bucket, (int)bucket_len - 1);
 571
 572         /* ...and add it to back propagation list. */
 573         node->bucket_index = ARR_LEN(reduced_bucket);
 574         ARR_APP1(pbqp_node *, reduced_bucket, node);
 575
 576         if (edge == NULL) {
 577                 edge = alloc_edge(pbqp, src_node->index, tgt_node->index, mat);
 578         } else {
 579                 pbqp_matrix_add(edge->costs, mat);
 580
 581                 /* Free local matrix. */
 582                 obstack_free(&pbqp->obstack, mat);
 583
 584                 reorder_node(src_node);
 585                 reorder_node(tgt_node);
 586         }
 587
 588         if (pbqp->dump_file) {
 589                 fputs("<br>\nAfter reduction:<br>\n", pbqp->dump_file);
 590                 dump_edge(pbqp, edge);
 591         }
 592
 593         /* Edge has changed so we simplify it. */
 594         simplify_edge(pbqp, edge);
 595 }
 596
 597 void apply_RN(pbqp *pbqp)
 598 {
 599         pbqp_node  **bucket     = node_buckets[3];
 600         unsigned     bucket_len = ARR_LEN(bucket);
 601         pbqp_node   *node       = bucket[bucket_len - 1];
 602         pbqp_edge   *edge;
 603         vector      *node_vec   = node->costs;
 604         vector      *vec;
 605         pbqp_matrix *mat;
 606         unsigned     edge_index;
 607         unsigned     edge_len   = ARR_LEN(node->edges);
 608         unsigned     node_index;
 609         unsigned     node_len   = ARR_LEN(node_vec);
 610         unsigned     min_index  = 0;
 611         num          min        = INF_COSTS;
 612         int          is_src;
 613
 614         assert(pbqp);
 615
 616         for (node_index = 0; node_index < node_len; ++node_index) {
 617                 num value = 0;
 618
 619                 for (edge_index = 0; edge_index < edge_len; ++edge_index) {
 620                         edge   = node->edges[edge_index];
 621                         mat    = edge->costs;
 622                         is_src = edge->src == node;
 623
 624                         if (is_src) {
 625                                 vec = vector_copy(pbqp, edge->tgt->costs);
 626                                 vector_add_matrix_row(vec, mat, node_index);
 627                         } else {
 628                                 vec = vector_copy(pbqp, edge->src->costs);
 629                                 vector_add_matrix_col(vec, mat, node_index);
 630                         }
 631
 632                         value = pbqp_add(value, vector_get_min(vec));
 633
 634                         obstack_free(&pbqp->obstack, vec);
 635                 }
 636
 637                 if (value < min) {
 638                         min = value;
 639                         min_index = node_index;
 640                 }
 641         }
 642
 643         node->solution = min_index;
 644
 645         /* Now that we found the local minimum set all other costs to infinity. */
 646         for (node_index = 0; node_index < node_len; ++node_index) {
 647                 if (node_index != min_index) {
 648                         node_vec->entries[node_index].data = INF_COSTS;
 649                 }
 650         }
 651
 652         /* Add all incident edges to edge bucket, since they are now independent. */
 653         for (edge_index = 0; edge_index < edge_len; ++edge_index) {
 654                 insert_into_edge_bucket(node->edges[node_index]);
 655         }
 656 }
 657
 658 void back_propagate_RI(pbqp *pbqp, pbqp_node *node)
 659 {
 660         pbqp_edge   *edge;
 661         pbqp_node   *other;
 662         pbqp_matrix *mat;
 663         vector      *vec;
 664         int          is_src;
 665
 666         assert(pbqp);
 667         assert(node);
 668
 669         edge = node->edges[0];
 670         mat = edge->costs;
 671         is_src = edge->src == node;
 672         vec = node->costs;
 673
 674         if (is_src) {
 675                 other = edge->tgt;
 676                 assert(other);
 677                 vector_add_matrix_col(vec, mat, other->solution);
 678         } else {
 679                 other = edge->src;
 680                 assert(other);
 681                 vector_add_matrix_row(vec, mat, other->solution);
 682         }
 683
 684         node->solution = vector_get_min_index(vec);
 685         if (pbqp->dump_file) {
 686                 fprintf(pbqp->dump_file, "node n%d is set to %d<br>\n", node->index, node->solution);
 687         }
 688 }
 689
 690 void back_propagate_RII(pbqp *pbqp, pbqp_node *node)
 691 {
 692         pbqp_edge   *src_edge   = node->edges[0];
 693         pbqp_edge   *tgt_edge   = node->edges[1];
 694         int          src_is_src = src_edge->src == node;
 695         int          tgt_is_src = tgt_edge->src == node;
 696         pbqp_matrix *src_mat;
 697         pbqp_matrix *tgt_mat;
 698         pbqp_node   *src_node;
 699         pbqp_node   *tgt_node;
 700         vector      *vec;
 701         vector      *node_vec;
 702         unsigned     col_index;
 703         unsigned     row_index;
 704
 705         assert(pbqp);
 706
 707         if (src_is_src) {
 708                 src_node = src_edge->tgt;
 709         } else {
 710                 src_node = src_edge->src;
 711         }
 712
 713         if (tgt_is_src) {
 714                 tgt_node = tgt_edge->tgt;
 715         } else {
 716                 tgt_node = tgt_edge->src;
 717         }
 718
 719         /* Swap nodes if necessary. */
 720         if (tgt_node->index < src_node->index) {
 721                 pbqp_node *tmp_node;
 722                 pbqp_edge *tmp_edge;
 723
 724                 tmp_node = src_node;
 725                 src_node = tgt_node;
 726                 tgt_node = tmp_node;
 727
 728                 tmp_edge = src_edge;
 729                 src_edge = tgt_edge;
 730                 tgt_edge = tmp_edge;
 731
 732                 src_is_src = src_edge->src == node;
 733                 tgt_is_src = tgt_edge->src == node;
 734         }
 735
 736         src_mat = src_edge->costs;
 737         tgt_mat = tgt_edge->costs;
 738
 739         node_vec = node->costs;
 740
 741         row_index = src_node->solution;
 742         col_index = tgt_node->solution;
 743
 744         vec = vector_copy(pbqp, node_vec);
 745
 746         if (src_is_src) {
 747                 vector_add_matrix_col(vec, src_mat, row_index);
 748         } else {
 749                 vector_add_matrix_row(vec, src_mat, row_index);
 750         }
 751
 752         if (tgt_is_src) {
 753                 vector_add_matrix_col(vec, tgt_mat, col_index);
 754         } else {
 755                 vector_add_matrix_row(vec, tgt_mat, col_index);
 756         }
 757
 758         node->solution = vector_get_min_index(vec);
 759         if (pbqp->dump_file) {
 760                 fprintf(pbqp->dump_file, "node n%d is set to %d<br>\n", node->index, node->solution);
 761         }
 762
 763         obstack_free(&pbqp->obstack, vec);
 764 }
 765
 766 int node_is_reduced(pbqp_node *node)
 767 {
 768         if (!reduced_bucket) return 0;
 769
 770         assert(node);
 771         if (ARR_LEN(node->edges) == 0) return 1;
 772
 773         unsigned bucket_length = ARR_LEN(reduced_bucket);
 774         unsigned bucket_index  = node->bucket_index;
 775
 776         return bucket_index < bucket_length && reduced_bucket[bucket_index] == node;
 777 }