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 #if KAPS_STATISTIC
  22 static int dump = 0;
  23 #endif
  24
  25 /* Forward declarations. */
  26 static void apply_Brute_Force(pbqp *pbqp);
  27
  28 static void insert_into_edge_bucket(pbqp_edge *edge)
  29 {
  30         if (edge_bucket_contains(edge_bucket, edge)) {
  31                 /* Edge is already inserted. */
  32                 return;
  33         }
  34
  35         edge_bucket_insert(&edge_bucket, edge);
  36 }
  37
  38 static void init_buckets(void)
  39 {
  40         int i;
  41
  42         edge_bucket_init(&edge_bucket);
  43         node_bucket_init(&reduced_bucket);
  44
  45         for (i = 0; i < 4; ++i) {
  46                 node_bucket_init(&node_buckets[i]);
  47         }
  48 }
  49
  50 static void free_buckets(void)
  51 {
  52         int i;
  53
  54         for (i = 0; i < 4; ++i) {
  55                 node_bucket_free(&node_buckets[i]);
  56         }
  57
  58         edge_bucket_free(&edge_bucket);
  59         node_bucket_free(&reduced_bucket);
  60
  61         buckets_filled = 0;
  62 }
  63
  64 static void fill_node_buckets(pbqp *pbqp)
  65 {
  66         unsigned node_index;
  67         unsigned node_len;
  68
  69         assert(pbqp);
  70         node_len = pbqp->num_nodes;
  71
  72         for (node_index = 0; node_index < node_len; ++node_index) {
  73                 unsigned   degree;
  74                 pbqp_node *node = get_node(pbqp, node_index);
  75
  76                 if (!node) continue;
  77
  78                 degree = pbqp_node_get_degree(node);
  79
  80                 /* We have only one bucket for nodes with arity >= 3. */
  81                 if (degree > 3) {
  82                         degree = 3;
  83                 }
  84
  85                 node_bucket_insert(&node_buckets[degree], node);
  86         }
  87
  88         buckets_filled = 1;
  89 }
  90
  91 static void normalize_towards_source(pbqp *pbqp, pbqp_edge *edge)
  92 {
  93         pbqp_matrix    *mat;
  94         pbqp_node      *src_node;
  95         pbqp_node      *tgt_node;
  96         vector         *src_vec;
  97         vector         *tgt_vec;
  98         int             src_len;
  99         int             tgt_len;
 100         int             src_index;
 101
 102         assert(pbqp);
 103         assert(edge);
 104
 105         src_node = edge->src;
 106         tgt_node = edge->tgt;
 107         assert(src_node);
 108         assert(tgt_node);
 109
 110         src_vec = src_node->costs;
 111         tgt_vec = tgt_node->costs;
 112         assert(src_vec);
 113         assert(tgt_vec);
 114
 115         src_len = src_vec->len;
 116         tgt_len = tgt_vec->len;
 117         assert(src_len > 0);
 118         assert(tgt_len > 0);
 119
 120         mat = edge->costs;
 121         assert(mat);
 122
 123         /* Normalize towards source node. */
 124         for (src_index = 0; src_index < src_len; ++src_index) {
 125                 num min = pbqp_matrix_get_row_min(mat, src_index, tgt_vec);
 126
 127                 if (min != 0) {
 128                         if (src_vec->entries[src_index].data == INF_COSTS) {
 129                                 pbqp_matrix_set_row_value(mat, src_index, 0);
 130                         } else {
 131                                 pbqp_matrix_sub_row_value(mat, src_index, tgt_vec, min);
 132                         }
 133                         src_vec->entries[src_index].data = pbqp_add(
 134                                         src_vec->entries[src_index].data, min);
 135
 136                         if (min == INF_COSTS) {
 137                                 unsigned edge_index;
 138                                 unsigned edge_len = pbqp_node_get_degree(src_node);
 139
 140                                 for (edge_index = 0; edge_index < edge_len; ++edge_index) {
 141                                         pbqp_edge *edge_candidate = src_node->edges[edge_index];
 142                                         if (edge_candidate != edge) {
 143                                                 insert_into_edge_bucket(edge_candidate);
 144                                         }
 145                                 }
 146                         }
 147                 }
 148         }
 149 }
 150
 151 static void normalize_towards_target(pbqp *pbqp, pbqp_edge *edge)
 152 {
 153         pbqp_matrix    *mat;
 154         pbqp_node      *src_node;
 155         pbqp_node      *tgt_node;
 156         vector         *src_vec;
 157         vector         *tgt_vec;
 158         int             src_len;
 159         int             tgt_len;
 160         int             tgt_index;
 161
 162         assert(pbqp);
 163         assert(edge);
 164
 165         src_node = edge->src;
 166         tgt_node = edge->tgt;
 167         assert(src_node);
 168         assert(tgt_node);
 169
 170         src_vec = src_node->costs;
 171         tgt_vec = tgt_node->costs;
 172         assert(src_vec);
 173         assert(tgt_vec);
 174
 175         src_len = src_vec->len;
 176         tgt_len = tgt_vec->len;
 177         assert(src_len > 0);
 178         assert(tgt_len > 0);
 179
 180         mat = edge->costs;
 181         assert(mat);
 182
 183         for (tgt_index = 0; tgt_index < tgt_len; ++tgt_index) {
 184                 num min = pbqp_matrix_get_col_min(mat, tgt_index, src_vec);
 185
 186                 if (min != 0) {
 187                         if (tgt_vec->entries[tgt_index].data == INF_COSTS) {
 188                                 pbqp_matrix_set_col_value(mat, tgt_index, 0);
 189                         } else {
 190                                 pbqp_matrix_sub_col_value(mat, tgt_index, src_vec, min);
 191                         }
 192                         tgt_vec->entries[tgt_index].data = pbqp_add(
 193                                         tgt_vec->entries[tgt_index].data, min);
 194
 195                         if (min == INF_COSTS) {
 196                                 unsigned edge_index;
 197                                 unsigned edge_len = pbqp_node_get_degree(tgt_node);
 198
 199                                 for (edge_index = 0; edge_index < edge_len; ++edge_index) {
 200                                         pbqp_edge *edge_candidate = tgt_node->edges[edge_index];
 201                                         if (edge_candidate != edge) {
 202                                                 insert_into_edge_bucket(edge_candidate);
 203                                         }
 204                                 }
 205                         }
 206                 }
 207         }
 208 }
 209
 210 static void reorder_node(pbqp_node *node)
 211 {
 212         unsigned    degree     = pbqp_node_get_degree(node);
 213         /* Assume node lost one incident edge. */
 214         unsigned    old_degree = degree + 1;
 215
 216         if (!buckets_filled) return;
 217
 218         /* Same bucket as before */
 219         if (degree > 2) return;
 220
 221         if (!node_bucket_contains(node_buckets[old_degree], node)) {
 222                 /* Old arity is new arity, so we have nothing to do. */
 223                 assert(node_bucket_contains(node_buckets[degree], node));
 224                 return;
 225         }
 226
 227         /* Delete node from old bucket... */
 228         node_bucket_remove(&node_buckets[old_degree], node);
 229
 230         /* ..and add to new one. */
 231         node_bucket_insert(&node_buckets[degree], node);
 232 }
 233
 234 static void check_melting_possibility(pbqp *pbqp, pbqp_edge *edge)
 235 {
 236         pbqp_matrix    *mat;
 237         pbqp_node      *src_node;
 238         pbqp_node      *tgt_node;
 239         vector         *src_vec;
 240         vector         *tgt_vec;
 241         int             src_len;
 242         int             tgt_len;
 243         int             src_index;
 244         int             tgt_index;
 245
 246         assert(pbqp);
 247         assert(edge);
 248
 249         src_node = edge->src;
 250         tgt_node = edge->tgt;
 251         assert(src_node);
 252         assert(tgt_node);
 253
 254         src_vec = src_node->costs;
 255         tgt_vec = tgt_node->costs;
 256         assert(src_vec);
 257         assert(tgt_vec);
 258
 259         src_len = src_vec->len;
 260         tgt_len = tgt_vec->len;
 261         assert(src_len > 0);
 262         assert(tgt_len > 0);
 263
 264         mat = edge->costs;
 265         assert(mat);
 266
 267         if (src_len == 1 && tgt_len == 1) {
 268                 //panic("Something is wrong");
 269         }
 270
 271         int allRowsOk = 1;
 272         for (src_index = 0; src_index < src_len; ++src_index) {
 273                 int onlyOneZero = 0;
 274                 if (src_vec->entries[src_index].data == INF_COSTS) {
 275                         continue;
 276                 }
 277                 for (tgt_index = 0; tgt_index < tgt_len; ++tgt_index) {
 278                         if (tgt_vec->entries[tgt_index].data == INF_COSTS) {
 279                                 continue;
 280                         }
 281                         if (mat->entries[src_index * tgt_len + tgt_index] == 0) {
 282                                 if (onlyOneZero) {
 283                                         onlyOneZero = 0;
 284                                         break;
 285                                 } else {
 286                                         onlyOneZero = 1;
 287                                         continue;
 288                                 }
 289                         }
 290                         if (mat->entries[src_index * tgt_len + tgt_index] == INF_COSTS) {
 291                                 continue;
 292                         }
 293                         onlyOneZero = 0;
 294                         break;
 295                 }
 296                 allRowsOk &= onlyOneZero;
 297         }
 298
 299         int allColsOk = 1;
 300         for (tgt_index = 0; tgt_index < tgt_len; ++tgt_index) {
 301                 int onlyOneZero = 0;
 302                 if (tgt_vec->entries[tgt_index].data == INF_COSTS) {
 303                         continue;
 304                 }
 305                 for (src_index = 0; src_index < src_len; ++src_index) {
 306                         if (src_vec->entries[src_index].data == INF_COSTS) {
 307                                 continue;
 308                         }
 309                         if (mat->entries[src_index * tgt_len + tgt_index] == 0) {
 310                                 if (onlyOneZero) {
 311                                         onlyOneZero = 0;
 312                                         break;
 313                                 } else {
 314                                         onlyOneZero = 1;
 315                                         continue;
 316                                 }
 317                         }
 318                         if (mat->entries[src_index * tgt_len + tgt_index] == INF_COSTS) {
 319                                 continue;
 320                         }
 321                         onlyOneZero = 0;
 322                         break;
 323                 }
 324                 allColsOk &= onlyOneZero;
 325         }
 326
 327         if (allRowsOk && allColsOk) {
 328                 panic("Hurray");
 329         }
 330 }
 331
 332 static void simplify_edge(pbqp *pbqp, pbqp_edge *edge)
 333 {
 334         pbqp_matrix    *mat;
 335         pbqp_node      *src_node;
 336         pbqp_node      *tgt_node;
 337         vector         *src_vec;
 338         vector         *tgt_vec;
 339         int             src_len;
 340         int             tgt_len;
 341
 342         assert(pbqp);
 343         assert(edge);
 344
 345         src_node = edge->src;
 346         tgt_node = edge->tgt;
 347         assert(src_node);
 348         assert(tgt_node);
 349
 350         /* If edge are already deleted, we have nothing to do. */
 351         if (!is_connected(src_node, edge) || !is_connected(tgt_node, edge))
 352                 return;
 353
 354         if (pbqp->dump_file) {
 355                 char txt[100];
 356                 sprintf(txt, "Simplification of Edge n%d-n%d", src_node->index, tgt_node->index);
 357                 dump_section(pbqp->dump_file, 3, txt);
 358         }
 359
 360         src_vec = src_node->costs;
 361         tgt_vec = tgt_node->costs;
 362         assert(src_vec);
 363         assert(tgt_vec);
 364
 365         src_len = src_vec->len;
 366         tgt_len = tgt_vec->len;
 367         assert(src_len > 0);
 368         assert(tgt_len > 0);
 369
 370         mat = edge->costs;
 371         assert(mat);
 372
 373         if (pbqp->dump_file) {
 374                 fputs("Input:<br>\n", pbqp->dump_file);
 375                 dump_simplifyedge(pbqp, edge);
 376         }
 377
 378         normalize_towards_source(pbqp, edge);
 379         normalize_towards_target(pbqp, edge);
 380
 381         if (pbqp->dump_file) {
 382                 fputs("<br>\nOutput:<br>\n", pbqp->dump_file);
 383                 dump_simplifyedge(pbqp, edge);
 384         }
 385
 386         if (pbqp_matrix_is_zero(mat, src_vec, tgt_vec)) {
 387                 if (pbqp->dump_file) {
 388                         fputs("edge has been eliminated<br>\n", pbqp->dump_file);
 389                 }
 390
 391 #if KAPS_STATISTIC
 392                 if (dump == 0) {
 393                         pbqp->num_edges++;
 394                 }
 395 #endif
 396
 397                 delete_edge(edge);
 398                 reorder_node(src_node);
 399                 reorder_node(tgt_node);
 400         } else {
 401                 //check_melting_possibility(pbqp, edge);
 402         }
 403 }
 404
 405 static void initial_simplify_edges(pbqp *pbqp)
 406 {
 407         unsigned node_index;
 408         unsigned node_len;
 409
 410         assert(pbqp);
 411
 412         if (pbqp->dump_file) {
 413                 pbqp_dump_input(pbqp);
 414                 dump_section(pbqp->dump_file, 1, "2. Simplification of Cost Matrices");
 415         }
 416
 417         node_len = pbqp->num_nodes;
 418
 419         init_buckets();
 420
 421         /* First simplify all edges. */
 422         for (node_index = 0; node_index < node_len; ++node_index) {
 423                 unsigned    edge_index;
 424                 pbqp_node  *node = get_node(pbqp, node_index);
 425                 pbqp_edge **edges;
 426                 unsigned    edge_len;
 427
 428                 if (!node) continue;
 429
 430                 edges = node->edges;
 431                 edge_len = pbqp_node_get_degree(node);
 432
 433                 for (edge_index = 0; edge_index < edge_len; ++edge_index) {
 434                         pbqp_edge *edge = edges[edge_index];
 435
 436                         /* Simplify only once per edge. */
 437                         if (node != edge->src) continue;
 438
 439                         simplify_edge(pbqp, edge);
 440                 }
 441         }
 442 }
 443
 444 static num determine_solution(pbqp *pbqp)
 445 {
 446         unsigned node_index;
 447         unsigned node_len;
 448         num      solution   = 0;
 449         FILE     *file;
 450
 451         assert(pbqp);
 452         file = pbqp->dump_file;
 453
 454         if (file) {
 455                 dump_section(file, 1, "4. Determine Solution/Minimum");
 456                 dump_section(file, 2, "4.1. Trivial Solution");
 457         }
 458
 459         /* Solve trivial nodes and calculate solution. */
 460         node_len = node_bucket_get_length(node_buckets[0]);
 461
 462 #if KAPS_STATISTIC
 463         if (dump == 0) {
 464                 pbqp->num_r0 = node_len;
 465         }
 466 #endif
 467
 468         for (node_index = 0; node_index < node_len; ++node_index) {
 469                 pbqp_node *node = node_buckets[0][node_index];
 470                 assert(node);
 471
 472                 node->solution = vector_get_min_index(node->costs);
 473                 solution       = pbqp_add(solution,
 474                                 node->costs->entries[node->solution].data);
 475                 if (file) {
 476                         fprintf(file, "node n%d is set to %d<br>\n", node->index, node->solution);
 477                         dump_node(file, node);
 478                 }
 479         }
 480
 481         if (file) {
 482                 dump_section(file, 2, "Minimum");
 483                 fprintf(file, "Minimum is equal to %lld.", solution);
 484         }
 485
 486         return solution;
 487 }
 488
 489 static void back_propagate(pbqp *pbqp)
 490 {
 491         unsigned node_index;
 492         unsigned node_len   = node_bucket_get_length(reduced_bucket);
 493
 494         assert(pbqp);
 495         if (pbqp->dump_file) {
 496                 dump_section(pbqp->dump_file, 2, "Back Propagation");
 497         }
 498
 499         for (node_index = node_len; node_index > 0; --node_index) {
 500                 pbqp_node *node = reduced_bucket[node_index - 1];
 501
 502                 switch (pbqp_node_get_degree(node)) {
 503                         case 1:
 504                                 back_propagate_RI(pbqp, node);
 505                                 break;
 506                         case 2:
 507                                 back_propagate_RII(pbqp, node);
 508                                 break;
 509                         default:
 510                                 panic("Only nodes with degree one or two should be in this bucket");
 511                                 break;
 512                 }
 513         }
 514 }
 515
 516 static void apply_heuristic_reductions(pbqp *pbqp)
 517 {
 518         for (;;) {
 519                 if (edge_bucket_get_length(edge_bucket) > 0) {
 520                         apply_edge(pbqp);
 521                 } else if (node_bucket_get_length(node_buckets[1]) > 0) {
 522                         apply_RI(pbqp);
 523                 } else if (node_bucket_get_length(node_buckets[2]) > 0) {
 524                         apply_RII(pbqp);
 525                 } else if (node_bucket_get_length(node_buckets[3]) > 0) {
 526                         apply_RN(pbqp);
 527                 } else {
 528                         return;
 529                 }
 530         }
 531 }
 532
 533 void solve_pbqp_heuristical(pbqp *pbqp)
 534 {
 535         /* Reduce nodes degree ... */
 536         initial_simplify_edges(pbqp);
 537
 538         /* ... and put node into bucket representing their degree. */
 539         fill_node_buckets(pbqp);
 540
 541 #if KAPS_STATISTIC
 542         FILE *fh = fopen("solutions.pb", "a");
 543         fprintf(fh, "Solution");
 544         fclose(fh);
 545 #endif
 546
 547         apply_heuristic_reductions(pbqp);
 548
 549         pbqp->solution = determine_solution(pbqp);
 550
 551 #if KAPS_STATISTIC
 552         fh = fopen("solutions.pb", "a");
 553         fprintf(fh, ": %lld RE:%u R0:%u R1:%u R2:%u RN/BF:%u\n", pbqp->solution,
 554                                 pbqp->num_edges, pbqp->num_r0, pbqp->num_r1, pbqp->num_r2,
 555                                 pbqp->num_rn);
 556         fclose(fh);
 557 #endif
 558
 559         /* Solve reduced nodes. */
 560         back_propagate(pbqp);
 561
 562         free_buckets();
 563 }
 564
 565 void apply_edge(pbqp *pbqp)
 566 {
 567         pbqp_edge *edge = edge_bucket_pop(&edge_bucket);
 568
 569         simplify_edge(pbqp, edge);
 570 }
 571
 572 void apply_RI(pbqp *pbqp)
 573 {
 574         pbqp_node   *node       = node_bucket_pop(&node_buckets[1]);
 575         pbqp_edge   *edge       = node->edges[0];
 576         pbqp_matrix *mat        = edge->costs;
 577         int          is_src     = edge->src == node;
 578         pbqp_node   *other_node;
 579
 580         assert(pbqp_node_get_degree(node) == 1);
 581
 582         if (is_src) {
 583                 other_node = edge->tgt;
 584         } else {
 585                 other_node = edge->src;
 586         }
 587
 588         if (pbqp->dump_file) {
 589                 char     txt[100];
 590                 sprintf(txt, "RI-Reduction of Node n%d", node->index);
 591                 dump_section(pbqp->dump_file, 2, txt);
 592                 pbqp_dump_graph(pbqp);
 593                 fputs("<br>\nBefore reduction:<br>\n", pbqp->dump_file);
 594                 dump_node(pbqp->dump_file, node);
 595                 dump_node(pbqp->dump_file, other_node);
 596                 dump_edge(pbqp->dump_file, edge);
 597         }
 598
 599         if (is_src) {
 600                 pbqp_matrix_add_to_all_cols(mat, node->costs);
 601                 normalize_towards_target(pbqp, edge);
 602         } else {
 603                 pbqp_matrix_add_to_all_rows(mat, node->costs);
 604                 normalize_towards_source(pbqp, edge);
 605         }
 606         disconnect_edge(other_node, edge);
 607
 608         if (pbqp->dump_file) {
 609                 fputs("<br>\nAfter reduction:<br>\n", pbqp->dump_file);
 610                 dump_node(pbqp->dump_file, other_node);
 611         }
 612
 613         reorder_node(other_node);
 614
 615 #if KAPS_STATISTIC
 616         if (dump == 0) {
 617                 pbqp->num_r1++;
 618         }
 619 #endif
 620
 621         /* Add node to back propagation list. */
 622         node_bucket_insert(&reduced_bucket, node);
 623 }
 624
 625 void apply_RII(pbqp *pbqp)
 626 {
 627         pbqp_node   *node       = node_bucket_pop(&node_buckets[2]);
 628         pbqp_edge   *src_edge   = node->edges[0];
 629         pbqp_edge   *tgt_edge   = node->edges[1];
 630         int          src_is_src = src_edge->src == node;
 631         int          tgt_is_src = tgt_edge->src == node;
 632         pbqp_matrix *src_mat;
 633         pbqp_matrix *tgt_mat;
 634         pbqp_node   *src_node;
 635         pbqp_node   *tgt_node;
 636         pbqp_matrix *mat;
 637         vector      *vec;
 638         vector      *node_vec;
 639         vector      *src_vec;
 640         vector      *tgt_vec;
 641         unsigned     col_index;
 642         unsigned     col_len;
 643         unsigned     row_index;
 644         unsigned     row_len;
 645         unsigned     node_len;
 646
 647         assert(pbqp);
 648         assert(pbqp_node_get_degree(node) == 2);
 649
 650         if (src_is_src) {
 651                 src_node = src_edge->tgt;
 652         } else {
 653                 src_node = src_edge->src;
 654         }
 655
 656         if (tgt_is_src) {
 657                 tgt_node = tgt_edge->tgt;
 658         } else {
 659                 tgt_node = tgt_edge->src;
 660         }
 661
 662         /* Swap nodes if necessary. */
 663         if (tgt_node->index < src_node->index) {
 664                 pbqp_node *tmp_node;
 665                 pbqp_edge *tmp_edge;
 666
 667                 tmp_node = src_node;
 668                 src_node = tgt_node;
 669                 tgt_node = tmp_node;
 670
 671                 tmp_edge = src_edge;
 672                 src_edge = tgt_edge;
 673                 tgt_edge = tmp_edge;
 674
 675                 src_is_src = src_edge->src == node;
 676                 tgt_is_src = tgt_edge->src == node;
 677         }
 678
 679         if (pbqp->dump_file) {
 680                 char     txt[100];
 681                 sprintf(txt, "RII-Reduction of Node n%d", node->index);
 682                 dump_section(pbqp->dump_file, 2, txt);
 683                 pbqp_dump_graph(pbqp);
 684                 fputs("<br>\nBefore reduction:<br>\n", pbqp->dump_file);
 685                 dump_node(pbqp->dump_file, src_node);
 686                 dump_edge(pbqp->dump_file, src_edge);
 687                 dump_node(pbqp->dump_file, node);
 688                 dump_edge(pbqp->dump_file, tgt_edge);
 689                 dump_node(pbqp->dump_file, tgt_node);
 690         }
 691
 692         src_mat = src_edge->costs;
 693         tgt_mat = tgt_edge->costs;
 694
 695         src_vec  = src_node->costs;
 696         tgt_vec  = tgt_node->costs;
 697         node_vec = node->costs;
 698
 699         row_len  = src_vec->len;
 700         col_len  = tgt_vec->len;
 701         node_len = node_vec->len;
 702
 703         mat = pbqp_matrix_alloc(pbqp, row_len, col_len);
 704
 705         for (row_index = 0; row_index < row_len; ++row_index) {
 706                 for (col_index = 0; col_index < col_len; ++col_index) {
 707                         vec = vector_copy(pbqp, node_vec);
 708
 709                         if (src_is_src) {
 710                                 vector_add_matrix_col(vec, src_mat, row_index);
 711                         } else {
 712                                 vector_add_matrix_row(vec, src_mat, row_index);
 713                         }
 714
 715                         if (tgt_is_src) {
 716                                 vector_add_matrix_col(vec, tgt_mat, col_index);
 717                         } else {
 718                                 vector_add_matrix_row(vec, tgt_mat, col_index);
 719                         }
 720
 721                         mat->entries[row_index * col_len + col_index] = vector_get_min(vec);
 722
 723                         obstack_free(&pbqp->obstack, vec);
 724                 }
 725         }
 726
 727         pbqp_edge *edge = get_edge(pbqp, src_node->index, tgt_node->index);
 728
 729         /* Disconnect node. */
 730         disconnect_edge(src_node, src_edge);
 731         disconnect_edge(tgt_node, tgt_edge);
 732
 733 #if KAPS_STATISTIC
 734         if (dump == 0) {
 735                 pbqp->num_r2++;
 736         }
 737 #endif
 738
 739         /* Add node to back propagation list. */
 740         node_bucket_insert(&reduced_bucket, node);
 741
 742         if (edge == NULL) {
 743                 edge = alloc_edge(pbqp, src_node->index, tgt_node->index, mat);
 744         } else {
 745                 pbqp_matrix_add(edge->costs, mat);
 746
 747                 /* Free local matrix. */
 748                 obstack_free(&pbqp->obstack, mat);
 749
 750                 reorder_node(src_node);
 751                 reorder_node(tgt_node);
 752         }
 753
 754         if (pbqp->dump_file) {
 755                 fputs("<br>\nAfter reduction:<br>\n", pbqp->dump_file);
 756                 dump_edge(pbqp->dump_file, edge);
 757         }
 758
 759         /* Edge has changed so we simplify it. */
 760         simplify_edge(pbqp, edge);
 761 }
 762
 763 static void select_alternative(pbqp_node *node, unsigned selected_index)
 764 {
 765         unsigned  edge_index;
 766         unsigned  node_index;
 767         unsigned  node_len;
 768         vector   *node_vec;
 769         unsigned  max_degree = pbqp_node_get_degree(node);
 770
 771         assert(node);
 772         node->solution = selected_index;
 773         node_vec = node->costs;
 774         node_len = node_vec->len;
 775         assert(selected_index < node_len);
 776
 777         /* Set all other costs to infinity. */
 778         for (node_index = 0; node_index < node_len; ++node_index) {
 779                 if (node_index != selected_index) {
 780                         node_vec->entries[node_index].data = INF_COSTS;
 781                 }
 782         }
 783
 784         /* Add all incident edges to edge bucket, since they are now independent. */
 785         for (edge_index = 0; edge_index < max_degree; ++edge_index) {
 786                 insert_into_edge_bucket(node->edges[edge_index]);
 787         }
 788 }
 789
 790 static pbqp_node *get_node_with_max_degree(void)
 791 {
 792         pbqp_node  **bucket       = node_buckets[3];
 793         unsigned     bucket_len   = node_bucket_get_length(bucket);
 794         unsigned     bucket_index;
 795         unsigned     max_degree   = 0;
 796         pbqp_node   *result       = NULL;
 797
 798         for (bucket_index = 0; bucket_index < bucket_len; ++bucket_index) {
 799                 pbqp_node *candidate = bucket[bucket_index];
 800                 unsigned   degree    = pbqp_node_get_degree(candidate);
 801
 802                 if (degree > max_degree) {
 803                         result = candidate;
 804                         max_degree = degree;
 805                 }
 806         }
 807
 808         return result;
 809 }
 810
 811 static unsigned get_local_minimal_alternative(pbqp *pbqp, pbqp_node *node)
 812 {
 813         pbqp_edge   *edge;
 814         vector      *node_vec;
 815         vector      *vec;
 816         pbqp_matrix *mat;
 817         unsigned     edge_index;
 818         unsigned     max_degree   = 0;
 819         unsigned     node_index;
 820         unsigned     node_len;
 821         unsigned     min_index    = 0;
 822         num          min          = INF_COSTS;
 823         int          is_src;
 824
 825         assert(pbqp);
 826         assert(node);
 827         node_vec = node->costs;
 828         node_len = node_vec->len;
 829
 830         for (node_index = 0; node_index < node_len; ++node_index) {
 831                 num value = node_vec->entries[node_index].data;
 832
 833                 for (edge_index = 0; edge_index < max_degree; ++edge_index) {
 834                         edge   = node->edges[edge_index];
 835                         mat    = edge->costs;
 836                         is_src = edge->src == node;
 837
 838                         if (is_src) {
 839                                 vec = vector_copy(pbqp, edge->tgt->costs);
 840                                 vector_add_matrix_row(vec, mat, node_index);
 841                         } else {
 842                                 vec = vector_copy(pbqp, edge->src->costs);
 843                                 vector_add_matrix_col(vec, mat, node_index);
 844                         }
 845
 846                         value = pbqp_add(value, vector_get_min(vec));
 847
 848                         obstack_free(&pbqp->obstack, vec);
 849                 }
 850
 851                 if (value < min) {
 852                         min = value;
 853                         min_index = node_index;
 854                 }
 855         }
 856
 857         return min_index;
 858 }
 859
 860 void apply_RN(pbqp *pbqp)
 861 {
 862         pbqp_node   *node         = NULL;
 863         unsigned     min_index    = 0;
 864
 865         assert(pbqp);
 866
 867         /* We want to reduce a node with maximum degree. */
 868         node = get_node_with_max_degree();
 869         assert(node);
 870         assert(pbqp_node_get_degree(node) > 2);
 871
 872         if (pbqp->dump_file) {
 873                 char     txt[100];
 874                 sprintf(txt, "RN-Reduction of Node n%d", node->index);
 875                 dump_section(pbqp->dump_file, 2, txt);
 876                 pbqp_dump_graph(pbqp);
 877         }
 878
 879         min_index = get_local_minimal_alternative(pbqp, node);
 880
 881         if (pbqp->dump_file) {
 882                 fprintf(pbqp->dump_file, "node n%d is set to %d<br><br>\n",
 883                                         node->index, min_index);
 884         }
 885
 886 #if KAPS_STATISTIC
 887         if (dump == 0) {
 888                 FILE *fh = fopen("solutions.pb", "a");
 889                 fprintf(fh, "[%u]", min_index);
 890                 fclose(fh);
 891                 pbqp->num_rn++;
 892         }
 893 #endif
 894
 895         /* Now that we found the local minimum set all other costs to infinity. */
 896         select_alternative(node, min_index);
 897 }
 898
 899 static void apply_brute_force_reductions(pbqp *pbqp)
 900 {
 901         for (;;) {
 902                 if (edge_bucket_get_length(edge_bucket) > 0) {
 903                         apply_edge(pbqp);
 904                 } else if (node_bucket_get_length(node_buckets[1]) > 0) {
 905                         apply_RI(pbqp);
 906                 } else if (node_bucket_get_length(node_buckets[2]) > 0) {
 907                         apply_RII(pbqp);
 908                 } else if (node_bucket_get_length(node_buckets[3]) > 0) {
 909                         apply_Brute_Force(pbqp);
 910                 } else {
 911                         return;
 912                 }
 913         }
 914 }
 915
 916 static unsigned get_minimal_alternative(pbqp *pbqp, pbqp_node *node)
 917 {
 918         vector      *node_vec;
 919         unsigned     node_index;
 920         unsigned     node_len;
 921         unsigned     min_index    = 0;
 922         num          min          = INF_COSTS;
 923         unsigned     bucket_index;
 924
 925         assert(pbqp);
 926         assert(node);
 927         node_vec     = node->costs;
 928         node_len     = node_vec->len;
 929         bucket_index = node->bucket_index;
 930
 931         for (node_index = 0; node_index < node_len; ++node_index) {
 932                 pbqp_node_bucket bucket_deg3;
 933                 num              value;
 934                 unsigned         bucket_0_length;
 935                 unsigned         bucket_red_length;
 936
 937                 char *tmp = obstack_finish(&pbqp->obstack);
 938
 939                 node_bucket_init(&bucket_deg3);
 940
 941                 /* Some node buckets and the edge bucket should be empty. */
 942                 assert(node_bucket_get_length(node_buckets[1]) == 0);
 943                 assert(node_bucket_get_length(node_buckets[2]) == 0);
 944                 assert(edge_bucket_get_length(edge_bucket)     == 0);
 945
 946                 /* char *tmp = obstack_finish(&pbqp->obstack); */
 947
 948                 /* Save current PBQP state. */
 949                 node_bucket_copy(&bucket_deg3, node_buckets[3]);
 950                 node_bucket_shrink(&node_buckets[3], 0);
 951                 node_bucket_deep_copy(pbqp, &node_buckets[3], bucket_deg3);
 952                 node_bucket_update(pbqp, node_buckets[3]);
 953                 bucket_0_length   = node_bucket_get_length(node_buckets[0]);
 954                 bucket_red_length = node_bucket_get_length(reduced_bucket);
 955
 956                 /* Select alternative and solve PBQP recursively. */
 957                 select_alternative(node_buckets[3][bucket_index], node_index);
 958                 apply_brute_force_reductions(pbqp);
 959
 960                 value = determine_solution(pbqp);
 961
 962                 if (value < min) {
 963                         min = value;
 964                         min_index = node_index;
 965                 }
 966
 967                 /* Some node buckets and the edge bucket should still be empty. */
 968                 assert(node_bucket_get_length(node_buckets[1]) == 0);
 969                 assert(node_bucket_get_length(node_buckets[2]) == 0);
 970                 assert(edge_bucket_get_length(edge_bucket)     == 0);
 971
 972                 /* Clear modified buckets... */
 973                 node_bucket_shrink(&node_buckets[3], 0);
 974
 975                 /* ... and restore old PBQP state. */
 976                 node_bucket_shrink(&node_buckets[0], bucket_0_length);
 977                 node_bucket_shrink(&reduced_bucket, bucket_red_length);
 978                 node_bucket_copy(&node_buckets[3], bucket_deg3);
 979                 node_bucket_update(pbqp, node_buckets[3]);
 980
 981                 /* Free copies. */
 982                 /* obstack_free(&pbqp->obstack, tmp); */
 983                 node_bucket_free(&bucket_deg3);
 984
 985                 obstack_free(&pbqp->obstack, tmp);
 986         }
 987
 988         return min_index;
 989 }
 990
 991 void apply_Brute_Force(pbqp *pbqp)
 992 {
 993         pbqp_node   *node         = NULL;
 994         unsigned     min_index    = 0;
 995
 996         assert(pbqp);
 997
 998         /* We want to reduce a node with maximum degree. */
 999         node = get_node_with_max_degree();
1000         assert(node);
1001         assert(pbqp_node_get_degree(node) > 2);
1002
1003         if (pbqp->dump_file) {
1004                 char     txt[100];
1005                 sprintf(txt, "BF-Reduction of Node n%d", node->index);
1006                 dump_section(pbqp->dump_file, 2, txt);
1007                 pbqp_dump_graph(pbqp);
1008         }
1009
1010 #if KAPS_STATISTIC
1011         dump++;
1012 #endif
1013
1014         min_index = get_minimal_alternative(pbqp, node);
1015         node = pbqp->nodes[node->index];
1016
1017         if (pbqp->dump_file) {
1018                 fprintf(pbqp->dump_file, "node n%d is set to %d<br><br>\n",
1019                                         node->index, min_index);
1020         }
1021
1022 #if KAPS_STATISTIC
1023         dump--;
1024         if (dump == 0) {
1025                 FILE *fh = fopen("solutions.pb", "a");
1026                 fprintf(fh, "[%u]", min_index);
1027                 fclose(fh);
1028                 pbqp->num_bf++;
1029         }
1030 #endif
1031
1032         /* Now that we found the minimum set all other costs to infinity. */
1033         select_alternative(node, min_index);
1034 }
1035
1036 void solve_pbqp_brute_force(pbqp *pbqp)
1037 {
1038         /* Reduce nodes degree ... */
1039         initial_simplify_edges(pbqp);
1040
1041         /* ... and put node into bucket representing their degree. */
1042         fill_node_buckets(pbqp);
1043
1044 #if KAPS_STATISTIC
1045         FILE *fh = fopen("solutions.pb", "a");
1046         fprintf(fh, "Solution");
1047         fclose(fh);
1048 #endif
1049
1050         apply_brute_force_reductions(pbqp);
1051
1052         pbqp->solution = determine_solution(pbqp);
1053
1054 #if KAPS_STATISTIC
1055         fh = fopen("solutions.pb", "a");
1056         fprintf(fh, ": %lld RE:%u R0:%u R1:%u R2:%u RN/BF:%u\n", pbqp->solution,
1057                         pbqp->num_edges, pbqp->num_r0, pbqp->num_r1, pbqp->num_r2,
1058                         pbqp->num_bf);
1059         fclose(fh);
1060 #endif
1061
1062         /* Solve reduced nodes. */
1063         back_propagate(pbqp);
1064
1065         free_buckets();
1066 }
1067
1068 void back_propagate_RI(pbqp *pbqp, pbqp_node *node)
1069 {
1070         pbqp_edge   *edge;
1071         pbqp_node   *other;
1072         pbqp_matrix *mat;
1073         vector      *vec;
1074         int          is_src;
1075
1076         assert(pbqp);
1077         assert(node);
1078
1079         edge = node->edges[0];
1080         mat = edge->costs;
1081         is_src = edge->src == node;
1082         vec = node->costs;
1083
1084         if (is_src) {
1085                 other = edge->tgt;
1086                 assert(other);
1087
1088                 /* Update pointer for brute force solver. */
1089                 other = pbqp->nodes[other->index];
1090
1091                 node->solution = pbqp_matrix_get_col_min_index(mat, other->solution, vec);
1092         } else {
1093                 other = edge->src;
1094                 assert(other);
1095
1096                 /* Update pointer for brute force solver. */
1097                 other = pbqp->nodes[other->index];
1098
1099                 node->solution = pbqp_matrix_get_row_min_index(mat, other->solution, vec);
1100         }
1101
1102         if (pbqp->dump_file) {
1103                 fprintf(pbqp->dump_file, "node n%d is set to %d<br>\n", node->index, node->solution);
1104         }
1105 }
1106
1107 void back_propagate_RII(pbqp *pbqp, pbqp_node *node)
1108 {
1109         pbqp_edge   *src_edge   = node->edges[0];
1110         pbqp_edge   *tgt_edge   = node->edges[1];
1111         int          src_is_src = src_edge->src == node;
1112         int          tgt_is_src = tgt_edge->src == node;
1113         pbqp_matrix *src_mat;
1114         pbqp_matrix *tgt_mat;
1115         pbqp_node   *src_node;
1116         pbqp_node   *tgt_node;
1117         vector      *vec;
1118         vector      *node_vec;
1119         unsigned     col_index;
1120         unsigned     row_index;
1121
1122         assert(pbqp);
1123
1124         if (src_is_src) {
1125                 src_node = src_edge->tgt;
1126         } else {
1127                 src_node = src_edge->src;
1128         }
1129
1130         if (tgt_is_src) {
1131                 tgt_node = tgt_edge->tgt;
1132         } else {
1133                 tgt_node = tgt_edge->src;
1134         }
1135
1136         /* Swap nodes if necessary. */
1137         if (tgt_node->index < src_node->index) {
1138                 pbqp_node *tmp_node;
1139                 pbqp_edge *tmp_edge;
1140
1141                 tmp_node = src_node;
1142                 src_node = tgt_node;
1143                 tgt_node = tmp_node;
1144
1145                 tmp_edge = src_edge;
1146                 src_edge = tgt_edge;
1147                 tgt_edge = tmp_edge;
1148
1149                 src_is_src = src_edge->src == node;
1150                 tgt_is_src = tgt_edge->src == node;
1151         }
1152
1153         /* Update pointer for brute force solver. */
1154         src_node = pbqp->nodes[src_node->index];
1155         tgt_node = pbqp->nodes[tgt_node->index];
1156
1157         src_mat = src_edge->costs;
1158         tgt_mat = tgt_edge->costs;
1159
1160         node_vec = node->costs;
1161
1162         row_index = src_node->solution;
1163         col_index = tgt_node->solution;
1164
1165         vec = vector_copy(pbqp, node_vec);
1166
1167         if (src_is_src) {
1168                 vector_add_matrix_col(vec, src_mat, row_index);
1169         } else {
1170                 vector_add_matrix_row(vec, src_mat, row_index);
1171         }
1172
1173         if (tgt_is_src) {
1174                 vector_add_matrix_col(vec, tgt_mat, col_index);
1175         } else {
1176                 vector_add_matrix_row(vec, tgt_mat, col_index);
1177         }
1178
1179         node->solution = vector_get_min_index(vec);
1180         if (pbqp->dump_file) {
1181                 fprintf(pbqp->dump_file, "node n%d is set to %d<br>\n", node->index, node->solution);
1182         }
1183
1184         obstack_free(&pbqp->obstack, vec);
1185 }
1186
1187 int node_is_reduced(pbqp_node *node)
1188 {
1189         if (!reduced_bucket) return 0;
1190
1191         if (pbqp_node_get_degree(node) == 0) return 1;
1192
1193         return node_bucket_contains(reduced_bucket, node);
1194 }