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