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