nsz Git - libfirm/blob - heuristical.c

   1 #include "adt/array.h"
   2 #include "assert.h"
   3 #include "error.h"
   4
   5 #include "bucket.h"
   6 #include "heuristical.h"
   7 #include "html_dumper.h"
   8 #include "kaps.h"
   9 #include "matrix.h"
  10 #include "pbqp_edge.h"
  11 #include "pbqp_edge_t.h"
  12 #include "pbqp_node.h"
  13 #include "pbqp_node_t.h"
  14 #include "vector.h"
  15
  16 static pbqp_edge **edge_bucket;
  17 static pbqp_node **node_buckets[4];
  18 static pbqp_node **reduced_bucket = NULL;
  19 static int         buckets_filled = 0;
  20
  21 static void insert_into_edge_bucket(pbqp_edge *edge)
  22 {
  23         if (edge_bucket_contains(edge_bucket, edge)) {
  24                 /* Edge is already inserted. */
  25                 return;
  26         }
  27
  28         edge_bucket_insert(&edge_bucket, edge);
  29 }
  30
  31 static void init_buckets(void)
  32 {
  33         int i;
  34
  35         edge_bucket_init(&edge_bucket);
  36         node_bucket_init(&reduced_bucket);
  37
  38         for (i = 0; i < 4; ++i) {
  39                 node_bucket_init(&node_buckets[i]);
  40         }
  41 }
  42
  43 static void free_buckets(void)
  44 {
  45         int i;
  46
  47         for (i = 0; i < 4; ++i) {
  48                 node_bucket_free(&node_buckets[i]);
  49         }
  50
  51         edge_bucket_free(&edge_bucket);
  52         node_bucket_free(&reduced_bucket);
  53
  54         buckets_filled = 0;
  55 }
  56
  57 static void fill_node_buckets(pbqp *pbqp)
  58 {
  59         unsigned node_index;
  60         unsigned node_len;
  61
  62         assert(pbqp);
  63         node_len = pbqp->num_nodes;
  64
  65         for (node_index = 0; node_index < node_len; ++node_index) {
  66                 unsigned   arity;
  67                 pbqp_node *node = get_node(pbqp, node_index);
  68
  69                 if (!node) continue;
  70
  71                 arity = ARR_LEN(node->edges);
  72
  73                 /* We have only one bucket for nodes with arity >= 3. */
  74                 if (arity > 3) {
  75                         arity = 3;
  76                 }
  77
  78                 node_bucket_insert(&node_buckets[arity], node);
  79         }
  80
  81         buckets_filled = 1;
  82 }
  83
  84 static void normalize_towards_source(pbqp *pbqp, pbqp_edge *edge)
  85 {
  86         pbqp_matrix    *mat;
  87         pbqp_node      *src_node;
  88         pbqp_node      *tgt_node;
  89         vector         *src_vec;
  90         vector         *tgt_vec;
  91         int             src_len;
  92         int             tgt_len;
  93         int             src_index;
  94
  95         assert(pbqp);
  96         assert(edge);
  97
  98         src_node = edge->src;
  99         tgt_node = edge->tgt;
 100         assert(src_node);
 101         assert(tgt_node);
 102
 103         src_vec = src_node->costs;
 104         tgt_vec = tgt_node->costs;
 105         assert(src_vec);
 106         assert(tgt_vec);
 107
 108         src_len = src_vec->len;
 109         tgt_len = tgt_vec->len;
 110         assert(src_len > 0);
 111         assert(tgt_len > 0);
 112
 113         mat = edge->costs;
 114         assert(mat);
 115
 116         /* Normalize towards source node. */
 117         for (src_index = 0; src_index < src_len; ++src_index) {
 118                 num min = pbqp_matrix_get_row_min(mat, src_index, tgt_vec);
 119
 120                 if (min != 0) {
 121                         if (src_vec->entries[src_index].data == INF_COSTS) {
 122                                 pbqp_matrix_set_row_value(mat, src_index, 0);
 123                         } else {
 124                                 pbqp_matrix_sub_row_value(mat, src_index, tgt_vec, min);
 125                         }
 126                         src_vec->entries[src_index].data = pbqp_add(
 127                                         src_vec->entries[src_index].data, min);
 128
 129                         if (min == INF_COSTS) {
 130                                 unsigned edge_index;
 131                                 unsigned edge_len = ARR_LEN(src_node->edges);
 132
 133                                 for (edge_index = 0; edge_index < edge_len; ++edge_index) {
 134                                         pbqp_edge *edge_candidate = src_node->edges[edge_index];
 135                                         if (edge_candidate != edge) {
 136                                                 insert_into_edge_bucket(edge_candidate);
 137                                         }
 138                                 }
 139                         }
 140                 }
 141         }
 142 }
 143
 144 static void normalize_towards_target(pbqp *pbqp, pbqp_edge *edge)
 145 {
 146         pbqp_matrix    *mat;
 147         pbqp_node      *src_node;
 148         pbqp_node      *tgt_node;
 149         vector         *src_vec;
 150         vector         *tgt_vec;
 151         int             src_len;
 152         int             tgt_len;
 153         int             tgt_index;
 154
 155         assert(pbqp);
 156         assert(edge);
 157
 158         src_node = edge->src;
 159         tgt_node = edge->tgt;
 160         assert(src_node);
 161         assert(tgt_node);
 162
 163         src_vec = src_node->costs;
 164         tgt_vec = tgt_node->costs;
 165         assert(src_vec);
 166         assert(tgt_vec);
 167
 168         src_len = src_vec->len;
 169         tgt_len = tgt_vec->len;
 170         assert(src_len > 0);
 171         assert(tgt_len > 0);
 172
 173         mat = edge->costs;
 174         assert(mat);
 175
 176         for (tgt_index = 0; tgt_index < tgt_len; ++tgt_index) {
 177                 num min = pbqp_matrix_get_col_min(mat, tgt_index, src_vec);
 178
 179                 if (min != 0) {
 180                         if (tgt_vec->entries[tgt_index].data == INF_COSTS) {
 181                                 pbqp_matrix_set_col_value(mat, tgt_index, 0);
 182                         } else {
 183                                 pbqp_matrix_sub_col_value(mat, tgt_index, src_vec, min);
 184                         }
 185                         tgt_vec->entries[tgt_index].data = pbqp_add(
 186                                         tgt_vec->entries[tgt_index].data, min);
 187
 188                         if (min == INF_COSTS) {
 189                                 unsigned edge_index;
 190                                 unsigned edge_len = ARR_LEN(tgt_node->edges);
 191
 192                                 for (edge_index = 0; edge_index < edge_len; ++edge_index) {
 193                                         pbqp_edge *edge_candidate = tgt_node->edges[edge_index];
 194                                         if (edge_candidate != edge) {
 195                                                 insert_into_edge_bucket(edge_candidate);
 196                                         }
 197                                 }
 198                         }
 199                 }
 200         }
 201 }
 202
 203 static void reorder_node(pbqp_node *node)
 204 {
 205         unsigned    arity;
 206         unsigned    old_arity;
 207
 208         if (!buckets_filled) return;
 209
 210         assert(node);
 211
 212         arity = ARR_LEN(node->edges);
 213
 214         /* Same bucket as before */
 215         if (arity > 2) return;
 216
 217         /* Assume node lost one incident edge. */
 218         old_arity = arity + 1;
 219
 220         if (!node_bucket_contains(node_buckets[old_arity], node)) {
 221                 /* Old arity is new arity, so we have nothing to do. */
 222                 assert(node_bucket_contains(node_buckets[arity], node));
 223                 return;
 224         }
 225
 226         /* Delete node from old bucket... */
 227         node_bucket_remove(&node_buckets[old_arity], node);
 228
 229         /* ..and add to new one. */
 230         node_bucket_insert(&node_buckets[arity], node);
 231 }
 232
 233 static void check_melting_possibility(pbqp *pbqp, pbqp_edge *edge)
 234 {
 235         pbqp_matrix    *mat;
 236         pbqp_node      *src_node;
 237         pbqp_node      *tgt_node;
 238         vector         *src_vec;
 239         vector         *tgt_vec;
 240         int             src_len;
 241         int             tgt_len;
 242         int             src_index;
 243         int             tgt_index;
 244
 245         assert(pbqp);
 246         assert(edge);
 247
 248         src_node = edge->src;
 249         tgt_node = edge->tgt;
 250         assert(src_node);
 251         assert(tgt_node);
 252
 253         src_vec = src_node->costs;
 254         tgt_vec = tgt_node->costs;
 255         assert(src_vec);
 256         assert(tgt_vec);
 257
 258         src_len = src_vec->len;
 259         tgt_len = tgt_vec->len;
 260         assert(src_len > 0);
 261         assert(tgt_len > 0);
 262
 263         mat = edge->costs;
 264         assert(mat);
 265
 266         if (src_len == 1 && tgt_len == 1) {
 267                 //panic("Something is wrong");
 268         }
 269
 270         int allRowsOk = 1;
 271         for (src_index = 0; src_index < src_len; ++src_index) {
 272                 int onlyOneZero = 0;
 273                 if (src_vec->entries[src_index].data == INF_COSTS) {
 274                         continue;
 275                 }
 276                 for (tgt_index = 0; tgt_index < tgt_len; ++tgt_index) {
 277                         if (tgt_vec->entries[tgt_index].data == INF_COSTS) {
 278                                 continue;
 279                         }
 280                         if (mat->entries[src_index * tgt_len + tgt_index] == 0) {
 281                                 if (onlyOneZero) {
 282                                         onlyOneZero = 0;
 283                                         break;
 284                                 } else {
 285                                         onlyOneZero = 1;
 286                                         continue;
 287                                 }
 288                         }
 289                         if (mat->entries[src_index * tgt_len + tgt_index] == INF_COSTS) {
 290                                 continue;
 291                         }
 292                         onlyOneZero = 0;
 293                         break;
 294                 }
 295                 allRowsOk &= onlyOneZero;
 296         }
 297
 298         int allColsOk = 1;
 299         for (tgt_index = 0; tgt_index < tgt_len; ++tgt_index) {
 300                 int onlyOneZero = 0;
 301                 if (tgt_vec->entries[tgt_index].data == INF_COSTS) {
 302                         continue;
 303                 }
 304                 for (src_index = 0; src_index < src_len; ++src_index) {
 305                         if (src_vec->entries[src_index].data == INF_COSTS) {
 306                                 continue;
 307                         }
 308                         if (mat->entries[src_index * tgt_len + tgt_index] == 0) {
 309                                 if (onlyOneZero) {
 310                                         onlyOneZero = 0;
 311                                         break;
 312                                 } else {
 313                                         onlyOneZero = 1;
 314                                         continue;
 315                                 }
 316                         }
 317                         if (mat->entries[src_index * tgt_len + tgt_index] == INF_COSTS) {
 318                                 continue;
 319                         }
 320                         onlyOneZero = 0;
 321                         break;
 322                 }
 323                 allColsOk &= onlyOneZero;
 324         }
 325
 326         if (allRowsOk && allColsOk) {
 327                 panic("Hurray");
 328         }
 329 }
 330
 331 static void simplify_edge(pbqp *pbqp, pbqp_edge *edge)
 332 {
 333         pbqp_matrix    *mat;
 334         pbqp_node      *src_node;
 335         pbqp_node      *tgt_node;
 336         vector         *src_vec;
 337         vector         *tgt_vec;
 338         int             src_len;
 339         int             tgt_len;
 340
 341         assert(pbqp);
 342         assert(edge);
 343
 344         src_node = edge->src;
 345         tgt_node = edge->tgt;
 346         assert(src_node);
 347         assert(tgt_node);
 348
 349         /* If edge are already deleted, we have nothing to do. */
 350         if (!is_connected(src_node, edge) || !is_connected(tgt_node, edge))
 351                 return;
 352
 353         if (pbqp->dump_file) {
 354                 char txt[100];
 355                 sprintf(txt, "Simplification of Edge n%d-n%d", src_node->index, tgt_node->index);
 356                 dump_section(pbqp->dump_file, 3, txt);
 357         }
 358
 359         src_vec = src_node->costs;
 360         tgt_vec = tgt_node->costs;
 361         assert(src_vec);
 362         assert(tgt_vec);
 363
 364         src_len = src_vec->len;
 365         tgt_len = tgt_vec->len;
 366         assert(src_len > 0);
 367         assert(tgt_len > 0);
 368
 369         mat = edge->costs;
 370         assert(mat);
 371
 372         if (pbqp->dump_file) {
 373                 fputs("Input:<br>\n", pbqp->dump_file);
 374                 dump_simplifyedge(pbqp, edge);
 375         }
 376
 377         normalize_towards_source(pbqp, edge);
 378         normalize_towards_target(pbqp, edge);
 379
 380         if (pbqp->dump_file) {
 381                 fputs("<br>\nOutput:<br>\n", pbqp->dump_file);
 382                 dump_simplifyedge(pbqp, edge);
 383         }
 384
 385         if (pbqp_matrix_is_zero(mat, src_vec, tgt_vec)) {
 386                 if (pbqp->dump_file) {
 387                         fputs("edge has been eliminated<br>\n", pbqp->dump_file);
 388                 }
 389
 390                 delete_edge(edge);
 391                 reorder_node(src_node);
 392                 reorder_node(tgt_node);
 393         } else {
 394                 //check_melting_possibility(pbqp, edge);
 395         }
 396 }
 397
 398 void solve_pbqp_heuristical(pbqp *pbqp)
 399 {
 400         unsigned node_index;
 401         unsigned node_len;
 402
 403         assert(pbqp);
 404
 405         if (pbqp->dump_file) {
 406                 pbqp_dump_input(pbqp);
 407                 dump_section(pbqp->dump_file, 1, "2. Simplification of Cost Matrices");
 408         }
 409
 410         node_len = pbqp->num_nodes;
 411
 412         init_buckets();
 413
 414         /* First simplify all edges. */
 415         for (node_index = 0; node_index < node_len; ++node_index) {
 416                 unsigned    edge_index;
 417                 pbqp_node  *node = get_node(pbqp, node_index);
 418                 pbqp_edge **edges;
 419                 unsigned    edge_len;
 420
 421                 if (!node) continue;
 422
 423                 edges = node->edges;
 424                 edge_len = ARR_LEN(edges);
 425
 426                 for (edge_index = 0; edge_index < edge_len; ++edge_index) {
 427                         pbqp_edge *edge = edges[edge_index];
 428
 429                         /* Simplify only once per edge. */
 430                         if (node != edge->src) continue;
 431
 432                         simplify_edge(pbqp, edge);
 433                 }
 434         }
 435
 436         /* Put node into bucket representing their arity. */
 437         fill_node_buckets(pbqp);
 438
 439         for (;;) {
 440                 if (edge_bucket_get_length(edge_bucket) > 0) {
 441                         apply_edge(pbqp);
 442                 } else if (node_bucket_get_length(node_buckets[1]) > 0) {
 443                         apply_RI(pbqp);
 444                 } else if (node_bucket_get_length(node_buckets[2]) > 0) {
 445                         apply_RII(pbqp);
 446                 } else if (node_bucket_get_length(node_buckets[3]) > 0) {
 447                         apply_RN(pbqp);
 448                 } else {
 449                         break;
 450                 }
 451         }
 452
 453         if (pbqp->dump_file) {
 454                 dump_section(pbqp->dump_file, 1, "4. Determine Solution/Minimum");
 455                 dump_section(pbqp->dump_file, 2, "4.1. Trivial Solution");
 456         }
 457
 458         /* Solve trivial nodes and calculate solution. */
 459         node_len = node_bucket_get_length(node_buckets[0]);
 460         for (node_index = 0; node_index < node_len; ++node_index) {
 461                 pbqp_node *node = node_buckets[0][node_index];
 462                 assert(node);
 463
 464                 node->solution = vector_get_min_index(node->costs);
 465                 pbqp->solution = pbqp_add(pbqp->solution,
 466                                 node->costs->entries[node->solution].data);
 467                 if (pbqp->dump_file) {
 468                         fprintf(pbqp->dump_file, "node n%d is set to %d<br>\n", node->index, node->solution);
 469                         dump_node(pbqp, node);
 470                 }
 471         }
 472
 473         if (pbqp->dump_file) {
 474                 dump_section(pbqp->dump_file, 2, "Minimum");
 475                 fprintf(pbqp->dump_file, "Minimum is equal to %lld.", pbqp->solution);
 476                 dump_section(pbqp->dump_file, 2, "Back Propagation");
 477         }
 478
 479         /* Solve reduced nodes. */
 480         node_len = node_bucket_get_length(reduced_bucket);
 481         for (node_index = node_len; node_index > 0; --node_index) {
 482                 pbqp_node *node = reduced_bucket[node_index - 1];
 483                 assert(node);
 484
 485                 switch (ARR_LEN(node->edges)) {
 486                         case 1:
 487                                 back_propagate_RI(pbqp, node);
 488                                 break;
 489                         case 2:
 490                                 back_propagate_RII(pbqp, node);
 491                                 break;
 492                         default:
 493                                 panic("Only nodes with degree one or two should be in this bucket");
 494                                 break;
 495                 }
 496         }
 497
 498         free_buckets();
 499 }
 500
 501 void apply_edge(pbqp *pbqp)
 502 {
 503         pbqp_edge *edge = edge_bucket_pop(&edge_bucket);
 504
 505         simplify_edge(pbqp, edge);
 506 }
 507
 508 void apply_RI(pbqp *pbqp)
 509 {
 510         pbqp_node   *node       = node_bucket_pop(&node_buckets[1]);
 511         pbqp_edge   *edge       = node->edges[0];
 512         pbqp_matrix *mat        = edge->costs;
 513         int          is_src     = edge->src == node;
 514         pbqp_node   *other_node;
 515
 516         if (is_src) {
 517                 other_node = edge->tgt;
 518         } else {
 519                 other_node = edge->src;
 520         }
 521
 522         if (pbqp->dump_file) {
 523                 char     txt[100];
 524                 sprintf(txt, "RI-Reduction of Node n%d", node->index);
 525                 dump_section(pbqp->dump_file, 2, txt);
 526                 pbqp_dump_graph(pbqp);
 527                 fputs("<br>\nBefore reduction:<br>\n", pbqp->dump_file);
 528                 dump_node(pbqp, node);
 529                 dump_node(pbqp, other_node);
 530                 dump_edge(pbqp, edge);
 531         }
 532
 533         if (is_src) {
 534                 pbqp_matrix_add_to_all_cols(mat, node->costs);
 535                 normalize_towards_target(pbqp, edge);
 536         } else {
 537                 pbqp_matrix_add_to_all_rows(mat, node->costs);
 538                 normalize_towards_source(pbqp, edge);
 539         }
 540         disconnect_edge(other_node, edge);
 541
 542         if (pbqp->dump_file) {
 543                 fputs("<br>\nAfter reduction:<br>\n", pbqp->dump_file);
 544                 dump_node(pbqp, other_node);
 545         }
 546
 547         reorder_node(other_node);
 548
 549         /* Add node to back propagation list. */
 550         node_bucket_insert(&reduced_bucket, node);
 551 }
 552
 553 void apply_RII(pbqp *pbqp)
 554 {
 555         pbqp_node   *node       = node_bucket_pop(&node_buckets[2]);
 556         pbqp_edge   *src_edge   = node->edges[0];
 557         pbqp_edge   *tgt_edge   = node->edges[1];
 558         int          src_is_src = src_edge->src == node;
 559         int          tgt_is_src = tgt_edge->src == node;
 560         pbqp_matrix *src_mat;
 561         pbqp_matrix *tgt_mat;
 562         pbqp_node   *src_node;
 563         pbqp_node   *tgt_node;
 564         pbqp_matrix *mat;
 565         vector      *vec;
 566         vector      *node_vec;
 567         vector      *src_vec;
 568         vector      *tgt_vec;
 569         unsigned     col_index;
 570         unsigned     col_len;
 571         unsigned     row_index;
 572         unsigned     row_len;
 573         unsigned     node_len;
 574
 575         assert(pbqp);
 576
 577         if (src_is_src) {
 578                 src_node = src_edge->tgt;
 579         } else {
 580                 src_node = src_edge->src;
 581         }
 582
 583         if (tgt_is_src) {
 584                 tgt_node = tgt_edge->tgt;
 585         } else {
 586                 tgt_node = tgt_edge->src;
 587         }
 588
 589         /* Swap nodes if necessary. */
 590         if (tgt_node->index < src_node->index) {
 591                 pbqp_node *tmp_node;
 592                 pbqp_edge *tmp_edge;
 593
 594                 tmp_node = src_node;
 595                 src_node = tgt_node;
 596                 tgt_node = tmp_node;
 597
 598                 tmp_edge = src_edge;
 599                 src_edge = tgt_edge;
 600                 tgt_edge = tmp_edge;
 601
 602                 src_is_src = src_edge->src == node;
 603                 tgt_is_src = tgt_edge->src == node;
 604         }
 605
 606         if (pbqp->dump_file) {
 607                 char     txt[100];
 608                 sprintf(txt, "RII-Reduction of Node n%d", node->index);
 609                 dump_section(pbqp->dump_file, 2, txt);
 610                 pbqp_dump_graph(pbqp);
 611                 fputs("<br>\nBefore reduction:<br>\n", pbqp->dump_file);
 612                 dump_node(pbqp, src_node);
 613                 dump_edge(pbqp, src_edge);
 614                 dump_node(pbqp, node);
 615                 dump_edge(pbqp, tgt_edge);
 616                 dump_node(pbqp, tgt_node);
 617         }
 618
 619         src_mat = src_edge->costs;
 620         tgt_mat = tgt_edge->costs;
 621
 622         src_vec  = src_node->costs;
 623         tgt_vec  = tgt_node->costs;
 624         node_vec = node->costs;
 625
 626         row_len  = src_vec->len;
 627         col_len  = tgt_vec->len;
 628         node_len = node_vec->len;
 629
 630         mat = pbqp_matrix_alloc(pbqp, row_len, col_len);
 631
 632         for (row_index = 0; row_index < row_len; ++row_index) {
 633                 for (col_index = 0; col_index < col_len; ++col_index) {
 634                         vec = vector_copy(pbqp, node_vec);
 635
 636                         if (src_is_src) {
 637                                 vector_add_matrix_col(vec, src_mat, row_index);
 638                         } else {
 639                                 vector_add_matrix_row(vec, src_mat, row_index);
 640                         }
 641
 642                         if (tgt_is_src) {
 643                                 vector_add_matrix_col(vec, tgt_mat, col_index);
 644                         } else {
 645                                 vector_add_matrix_row(vec, tgt_mat, col_index);
 646                         }
 647
 648                         mat->entries[row_index * col_len + col_index] = vector_get_min(vec);
 649
 650                         obstack_free(&pbqp->obstack, vec);
 651                 }
 652         }
 653
 654         pbqp_edge *edge = get_edge(pbqp, src_node->index, tgt_node->index);
 655
 656         /* Disconnect node. */
 657         disconnect_edge(src_node, src_edge);
 658         disconnect_edge(tgt_node, tgt_edge);
 659
 660         /* Add node to back propagation list. */
 661         node_bucket_insert(&reduced_bucket, node);
 662
 663         if (edge == NULL) {
 664                 edge = alloc_edge(pbqp, src_node->index, tgt_node->index, mat);
 665         } else {
 666                 pbqp_matrix_add(edge->costs, mat);
 667
 668                 /* Free local matrix. */
 669                 obstack_free(&pbqp->obstack, mat);
 670
 671                 reorder_node(src_node);
 672                 reorder_node(tgt_node);
 673         }
 674
 675         if (pbqp->dump_file) {
 676                 fputs("<br>\nAfter reduction:<br>\n", pbqp->dump_file);
 677                 dump_edge(pbqp, edge);
 678         }
 679
 680         /* Edge has changed so we simplify it. */
 681         simplify_edge(pbqp, edge);
 682 }
 683
 684 void apply_RN(pbqp *pbqp)
 685 {
 686         pbqp_node  **bucket       = node_buckets[3];
 687         unsigned     bucket_len   = node_bucket_get_length(bucket);
 688         unsigned     bucket_index;
 689         pbqp_node   *node         = NULL;
 690         pbqp_edge   *edge;
 691         vector      *node_vec;
 692         vector      *vec;
 693         pbqp_matrix *mat;
 694         unsigned     edge_index;
 695         unsigned     max_degree   = 0;
 696         unsigned     node_index;
 697         unsigned     node_len;
 698         unsigned     min_index    = 0;
 699         num          min          = INF_COSTS;
 700         int          is_src;
 701
 702         assert(pbqp);
 703
 704         /* Search for node with maximum degree. */
 705         for (bucket_index = 0; bucket_index < bucket_len; ++bucket_index) {
 706                 pbqp_node *candidate = bucket[bucket_index];
 707                 unsigned   degree    = ARR_LEN(candidate->edges);
 708
 709                 if (degree > max_degree) {
 710                         node = candidate;
 711                         max_degree = degree;
 712                 }
 713         }
 714         assert(node);
 715         node_vec = node->costs;
 716         node_len = node_vec->len;
 717
 718         if (pbqp->dump_file) {
 719                 char     txt[100];
 720                 sprintf(txt, "RN-Reduction of Node n%d", node->index);
 721                 dump_section(pbqp->dump_file, 2, txt);
 722                 pbqp_dump_graph(pbqp);
 723         }
 724
 725         for (node_index = 0; node_index < node_len; ++node_index) {
 726                 num value = node_vec->entries[node_index].data;
 727
 728                 for (edge_index = 0; edge_index < max_degree; ++edge_index) {
 729                         edge   = node->edges[edge_index];
 730                         mat    = edge->costs;
 731                         is_src = edge->src == node;
 732
 733                         if (is_src) {
 734                                 vec = vector_copy(pbqp, edge->tgt->costs);
 735                                 vector_add_matrix_row(vec, mat, node_index);
 736                         } else {
 737                                 vec = vector_copy(pbqp, edge->src->costs);
 738                                 vector_add_matrix_col(vec, mat, node_index);
 739                         }
 740
 741                         value = pbqp_add(value, vector_get_min(vec));
 742
 743                         obstack_free(&pbqp->obstack, vec);
 744                 }
 745
 746                 if (value < min) {
 747                         min = value;
 748                         min_index = node_index;
 749                 }
 750         }
 751
 752         if (pbqp->dump_file) {
 753                 fprintf(pbqp->dump_file, "node n%d is set to %d<br><br>\n",
 754                                         node->index, min_index);
 755                 fprintf(pbqp->dump_file, "Minimal cost of RN reduction: %lld<br>\n",
 756                                                         min);
 757         }
 758
 759         node->solution = min_index;
 760
 761         /* Now that we found the local minimum set all other costs to infinity. */
 762         for (node_index = 0; node_index < node_len; ++node_index) {
 763                 if (node_index != min_index) {
 764                         node_vec->entries[node_index].data = INF_COSTS;
 765                 }
 766         }
 767
 768         /* Add all incident edges to edge bucket, since they are now independent. */
 769         for (edge_index = 0; edge_index < max_degree; ++edge_index) {
 770                 insert_into_edge_bucket(node->edges[edge_index]);
 771         }
 772 }
 773
 774 void back_propagate_RI(pbqp *pbqp, pbqp_node *node)
 775 {
 776         pbqp_edge   *edge;
 777         pbqp_node   *other;
 778         pbqp_matrix *mat;
 779         vector      *vec;
 780         int          is_src;
 781
 782         assert(pbqp);
 783         assert(node);
 784
 785         edge = node->edges[0];
 786         mat = edge->costs;
 787         is_src = edge->src == node;
 788         vec = node->costs;
 789
 790         if (is_src) {
 791                 other = edge->tgt;
 792                 assert(other);
 793                 vector_add_matrix_col(vec, mat, other->solution);
 794         } else {
 795                 other = edge->src;
 796                 assert(other);
 797                 vector_add_matrix_row(vec, mat, other->solution);
 798         }
 799
 800         node->solution = vector_get_min_index(vec);
 801         if (pbqp->dump_file) {
 802                 fprintf(pbqp->dump_file, "node n%d is set to %d<br>\n", node->index, node->solution);
 803         }
 804 }
 805
 806 void back_propagate_RII(pbqp *pbqp, pbqp_node *node)
 807 {
 808         pbqp_edge   *src_edge   = node->edges[0];
 809         pbqp_edge   *tgt_edge   = node->edges[1];
 810         int          src_is_src = src_edge->src == node;
 811         int          tgt_is_src = tgt_edge->src == node;
 812         pbqp_matrix *src_mat;
 813         pbqp_matrix *tgt_mat;
 814         pbqp_node   *src_node;
 815         pbqp_node   *tgt_node;
 816         vector      *vec;
 817         vector      *node_vec;
 818         unsigned     col_index;
 819         unsigned     row_index;
 820
 821         assert(pbqp);
 822
 823         if (src_is_src) {
 824                 src_node = src_edge->tgt;
 825         } else {
 826                 src_node = src_edge->src;
 827         }
 828
 829         if (tgt_is_src) {
 830                 tgt_node = tgt_edge->tgt;
 831         } else {
 832                 tgt_node = tgt_edge->src;
 833         }
 834
 835         /* Swap nodes if necessary. */
 836         if (tgt_node->index < src_node->index) {
 837                 pbqp_node *tmp_node;
 838                 pbqp_edge *tmp_edge;
 839
 840                 tmp_node = src_node;
 841                 src_node = tgt_node;
 842                 tgt_node = tmp_node;
 843
 844                 tmp_edge = src_edge;
 845                 src_edge = tgt_edge;
 846                 tgt_edge = tmp_edge;
 847
 848                 src_is_src = src_edge->src == node;
 849                 tgt_is_src = tgt_edge->src == node;
 850         }
 851
 852         src_mat = src_edge->costs;
 853         tgt_mat = tgt_edge->costs;
 854
 855         node_vec = node->costs;
 856
 857         row_index = src_node->solution;
 858         col_index = tgt_node->solution;
 859
 860         vec = vector_copy(pbqp, node_vec);
 861
 862         if (src_is_src) {
 863                 vector_add_matrix_col(vec, src_mat, row_index);
 864         } else {
 865                 vector_add_matrix_row(vec, src_mat, row_index);
 866         }
 867
 868         if (tgt_is_src) {
 869                 vector_add_matrix_col(vec, tgt_mat, col_index);
 870         } else {
 871                 vector_add_matrix_row(vec, tgt_mat, col_index);
 872         }
 873
 874         node->solution = vector_get_min_index(vec);
 875         if (pbqp->dump_file) {
 876                 fprintf(pbqp->dump_file, "node n%d is set to %d<br>\n", node->index, node->solution);
 877         }
 878
 879         obstack_free(&pbqp->obstack, vec);
 880 }
 881
 882 int node_is_reduced(pbqp_node *node)
 883 {
 884         if (!reduced_bucket) return 0;
 885
 886         assert(node);
 887         if (ARR_LEN(node->edges) == 0) return 1;
 888
 889         return node_bucket_contains(reduced_bucket, node);
 890 }