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         unsigned    old_bucket_len;
 208         unsigned    old_bucket_index;
 209         pbqp_node **old_bucket;
 210         pbqp_node  *other;
 211
 212         if (!buckets_filled) return;
 213
 214         assert(node);
 215
 216         arity = ARR_LEN(node->edges);
 217
 218         /* Same bucket as before */
 219         if (arity > 2) return;
 220
 221         /* Assume node lost one incident edge. */
 222         old_arity        = arity + 1;
 223         old_bucket       = node_buckets[old_arity];
 224         old_bucket_len   = node_bucket_get_length(old_bucket);
 225         old_bucket_index = node->bucket_index;
 226
 227         if (old_bucket_len <= old_bucket_index || old_bucket[old_bucket_index]
 228                         != node) {
 229                 unsigned bucket_len = node_bucket_get_length(node_buckets[arity]);
 230
 231                 /* Old arity is new arity, so we have nothing to do. */
 232                 assert(old_bucket_index < bucket_len);
 233                 assert(node_buckets[arity][old_bucket_index] == node);
 234                 return;
 235         }
 236
 237         assert(old_bucket[old_bucket_index] == node);
 238
 239         /* Delete node from old bucket... */
 240         other                        = old_bucket[old_bucket_len - 1];
 241         other->bucket_index          = old_bucket_index;
 242         old_bucket[old_bucket_index] = other;
 243         ARR_SHRINKLEN(node_buckets[old_arity], old_bucket_len - 1);
 244
 245         /* ..and add to new one. */
 246         node->bucket_index = node_bucket_get_length(node_buckets[arity]);
 247         ARR_APP1(pbqp_node*, node_buckets[arity], node);
 248 }
 249
 250 static void simplify_edge(pbqp *pbqp, pbqp_edge *edge)
 251 {
 252         pbqp_matrix    *mat;
 253         pbqp_node      *src_node;
 254         pbqp_node      *tgt_node;
 255         vector         *src_vec;
 256         vector         *tgt_vec;
 257         int             src_len;
 258         int             tgt_len;
 259
 260         assert(pbqp);
 261         assert(edge);
 262
 263         src_node = edge->src;
 264         tgt_node = edge->tgt;
 265         assert(src_node);
 266         assert(tgt_node);
 267
 268         /* If edge are already deleted, we have nothing to do. */
 269         if (!is_connected(src_node, edge) || !is_connected(tgt_node, edge))
 270                 return;
 271
 272         if (pbqp->dump_file) {
 273                 char txt[100];
 274                 sprintf(txt, "Simplification of Edge n%d-n%d", src_node->index, tgt_node->index);
 275                 dump_section(pbqp->dump_file, 3, txt);
 276         }
 277
 278         src_vec = src_node->costs;
 279         tgt_vec = tgt_node->costs;
 280         assert(src_vec);
 281         assert(tgt_vec);
 282
 283         src_len = src_vec->len;
 284         tgt_len = tgt_vec->len;
 285         assert(src_len > 0);
 286         assert(tgt_len > 0);
 287
 288         mat = edge->costs;
 289         assert(mat);
 290
 291         if (pbqp->dump_file) {
 292                 fputs("Input:<br>\n", pbqp->dump_file);
 293                 dump_simplifyedge(pbqp, edge);
 294         }
 295
 296         normalize_towards_source(pbqp, edge);
 297         normalize_towards_target(pbqp, edge);
 298
 299         if (pbqp->dump_file) {
 300                 fputs("<br>\nOutput:<br>\n", pbqp->dump_file);
 301                 dump_simplifyedge(pbqp, edge);
 302         }
 303
 304         if (pbqp_matrix_is_zero(mat, src_vec, tgt_vec)) {
 305                 if (pbqp->dump_file) {
 306                         fputs("edge has been eliminated<br>\n", pbqp->dump_file);
 307                 }
 308
 309                 delete_edge(edge);
 310                 reorder_node(src_node);
 311                 reorder_node(tgt_node);
 312         }
 313 }
 314
 315 void solve_pbqp_heuristical(pbqp *pbqp)
 316 {
 317         unsigned node_index;
 318         unsigned node_len;
 319
 320         assert(pbqp);
 321
 322         if (pbqp->dump_file) {
 323                 pbqp_dump_input(pbqp);
 324                 dump_section(pbqp->dump_file, 1, "2. Simplification of Cost Matrices");
 325         }
 326
 327         node_len = pbqp->num_nodes;
 328
 329         init_buckets();
 330
 331         /* First simplify all edges. */
 332         for (node_index = 0; node_index < node_len; ++node_index) {
 333                 unsigned    edge_index;
 334                 pbqp_node  *node = get_node(pbqp, node_index);
 335                 pbqp_edge **edges;
 336                 unsigned    edge_len;
 337
 338                 if (!node) continue;
 339
 340                 edges = node->edges;
 341                 edge_len = ARR_LEN(edges);
 342
 343                 for (edge_index = 0; edge_index < edge_len; ++edge_index) {
 344                         pbqp_edge *edge = edges[edge_index];
 345
 346                         /* Simplify only once per edge. */
 347                         if (node != edge->src) continue;
 348
 349                         simplify_edge(pbqp, edge);
 350                 }
 351         }
 352
 353         /* Put node into bucket representing their arity. */
 354         fill_node_buckets(pbqp);
 355
 356         for (;;) {
 357                 if (edge_bucket_get_length(edge_bucket) > 0) {
 358                         apply_edge(pbqp);
 359                 } else if (node_bucket_get_length(node_buckets[1]) > 0) {
 360                         apply_RI(pbqp);
 361                 } else if (node_bucket_get_length(node_buckets[2]) > 0) {
 362                         apply_RII(pbqp);
 363                 } else if (node_bucket_get_length(node_buckets[3]) > 0) {
 364                         apply_RN(pbqp);
 365                 } else {
 366                         break;
 367                 }
 368         }
 369
 370         if (pbqp->dump_file) {
 371                 dump_section(pbqp->dump_file, 1, "4. Determine Solution/Minimum");
 372                 dump_section(pbqp->dump_file, 2, "4.1. Trivial Solution");
 373         }
 374
 375         /* Solve trivial nodes and calculate solution. */
 376         node_len = node_bucket_get_length(node_buckets[0]);
 377         for (node_index = 0; node_index < node_len; ++node_index) {
 378                 pbqp_node *node = node_buckets[0][node_index];
 379                 assert(node);
 380
 381                 node->solution = vector_get_min_index(node->costs);
 382                 pbqp->solution = pbqp_add(pbqp->solution,
 383                                 node->costs->entries[node->solution].data);
 384                 if (pbqp->dump_file) {
 385                         fprintf(pbqp->dump_file, "node n%d is set to %d<br>\n", node->index, node->solution);
 386                         dump_node(pbqp, node);
 387                 }
 388         }
 389
 390         if (pbqp->dump_file) {
 391                 dump_section(pbqp->dump_file, 2, "Minimum");
 392                 fprintf(pbqp->dump_file, "Minimum is equal to %lld.", pbqp->solution);
 393                 dump_section(pbqp->dump_file, 2, "Back Propagation");
 394         }
 395
 396         /* Solve reduced nodes. */
 397         node_len = node_bucket_get_length(reduced_bucket);
 398         for (node_index = node_len; node_index > 0; --node_index) {
 399                 pbqp_node *node = reduced_bucket[node_index - 1];
 400                 assert(node);
 401
 402                 switch (ARR_LEN(node->edges)) {
 403                         case 1:
 404                                 back_propagate_RI(pbqp, node);
 405                                 break;
 406                         case 2:
 407                                 back_propagate_RII(pbqp, node);
 408                                 break;
 409                         default:
 410                                 panic("Only nodes with degree one or two should be in this bucket");
 411                                 break;
 412                 }
 413         }
 414
 415         free_buckets();
 416 }
 417
 418 void apply_edge(pbqp *pbqp)
 419 {
 420         pbqp_edge *edge = edge_bucket_pop(&edge_bucket);
 421
 422         simplify_edge(pbqp, edge);
 423 }
 424
 425 void apply_RI(pbqp *pbqp)
 426 {
 427         pbqp_node   *node       = node_bucket_pop(&node_buckets[1]);
 428         pbqp_edge   *edge       = node->edges[0];
 429         pbqp_matrix *mat        = edge->costs;
 430         int          is_src     = edge->src == node;
 431         pbqp_node   *other_node;
 432
 433         if (is_src) {
 434                 other_node = edge->tgt;
 435         } else {
 436                 other_node = edge->src;
 437         }
 438
 439         if (pbqp->dump_file) {
 440                 char     txt[100];
 441                 sprintf(txt, "RI-Reduction of Node n%d", node->index);
 442                 dump_section(pbqp->dump_file, 2, txt);
 443                 pbqp_dump_graph(pbqp);
 444                 fputs("<br>\nBefore reduction:<br>\n", pbqp->dump_file);
 445                 dump_node(pbqp, node);
 446                 dump_node(pbqp, other_node);
 447                 dump_edge(pbqp, edge);
 448         }
 449
 450         if (is_src) {
 451                 pbqp_matrix_add_to_all_cols(mat, node->costs);
 452                 normalize_towards_target(pbqp, edge);
 453         } else {
 454                 pbqp_matrix_add_to_all_rows(mat, node->costs);
 455                 normalize_towards_source(pbqp, edge);
 456         }
 457         disconnect_edge(other_node, edge);
 458
 459         if (pbqp->dump_file) {
 460                 fputs("<br>\nAfter reduction:<br>\n", pbqp->dump_file);
 461                 dump_node(pbqp, other_node);
 462         }
 463
 464         reorder_node(other_node);
 465
 466         /* Add node to back propagation list. */
 467         node_bucket_insert(&reduced_bucket, node);
 468 }
 469
 470 void apply_RII(pbqp *pbqp)
 471 {
 472         pbqp_node   *node       = node_bucket_pop(&node_buckets[2]);
 473         pbqp_edge   *src_edge   = node->edges[0];
 474         pbqp_edge   *tgt_edge   = node->edges[1];
 475         int          src_is_src = src_edge->src == node;
 476         int          tgt_is_src = tgt_edge->src == node;
 477         pbqp_matrix *src_mat;
 478         pbqp_matrix *tgt_mat;
 479         pbqp_node   *src_node;
 480         pbqp_node   *tgt_node;
 481         pbqp_matrix *mat;
 482         vector      *vec;
 483         vector      *node_vec;
 484         vector      *src_vec;
 485         vector      *tgt_vec;
 486         unsigned     col_index;
 487         unsigned     col_len;
 488         unsigned     row_index;
 489         unsigned     row_len;
 490         unsigned     node_len;
 491
 492         assert(pbqp);
 493
 494         if (src_is_src) {
 495                 src_node = src_edge->tgt;
 496         } else {
 497                 src_node = src_edge->src;
 498         }
 499
 500         if (tgt_is_src) {
 501                 tgt_node = tgt_edge->tgt;
 502         } else {
 503                 tgt_node = tgt_edge->src;
 504         }
 505
 506         /* Swap nodes if necessary. */
 507         if (tgt_node->index < src_node->index) {
 508                 pbqp_node *tmp_node;
 509                 pbqp_edge *tmp_edge;
 510
 511                 tmp_node = src_node;
 512                 src_node = tgt_node;
 513                 tgt_node = tmp_node;
 514
 515                 tmp_edge = src_edge;
 516                 src_edge = tgt_edge;
 517                 tgt_edge = tmp_edge;
 518
 519                 src_is_src = src_edge->src == node;
 520                 tgt_is_src = tgt_edge->src == node;
 521         }
 522
 523         if (pbqp->dump_file) {
 524                 char     txt[100];
 525                 sprintf(txt, "RII-Reduction of Node n%d", node->index);
 526                 dump_section(pbqp->dump_file, 2, txt);
 527                 pbqp_dump_graph(pbqp);
 528                 fputs("<br>\nBefore reduction:<br>\n", pbqp->dump_file);
 529                 dump_node(pbqp, src_node);
 530                 dump_edge(pbqp, src_edge);
 531                 dump_node(pbqp, node);
 532                 dump_edge(pbqp, tgt_edge);
 533                 dump_node(pbqp, tgt_node);
 534         }
 535
 536         src_mat = src_edge->costs;
 537         tgt_mat = tgt_edge->costs;
 538
 539         src_vec  = src_node->costs;
 540         tgt_vec  = tgt_node->costs;
 541         node_vec = node->costs;
 542
 543         row_len  = src_vec->len;
 544         col_len  = tgt_vec->len;
 545         node_len = node_vec->len;
 546
 547         mat = pbqp_matrix_alloc(pbqp, row_len, col_len);
 548
 549         for (row_index = 0; row_index < row_len; ++row_index) {
 550                 for (col_index = 0; col_index < col_len; ++col_index) {
 551                         vec = vector_copy(pbqp, node_vec);
 552
 553                         if (src_is_src) {
 554                                 vector_add_matrix_col(vec, src_mat, row_index);
 555                         } else {
 556                                 vector_add_matrix_row(vec, src_mat, row_index);
 557                         }
 558
 559                         if (tgt_is_src) {
 560                                 vector_add_matrix_col(vec, tgt_mat, col_index);
 561                         } else {
 562                                 vector_add_matrix_row(vec, tgt_mat, col_index);
 563                         }
 564
 565                         mat->entries[row_index * col_len + col_index] = vector_get_min(vec);
 566
 567                         obstack_free(&pbqp->obstack, vec);
 568                 }
 569         }
 570
 571         pbqp_edge *edge = get_edge(pbqp, src_node->index, tgt_node->index);
 572
 573         /* Disconnect node. */
 574         disconnect_edge(src_node, src_edge);
 575         disconnect_edge(tgt_node, tgt_edge);
 576
 577         /* Add node to back propagation list. */
 578         node_bucket_insert(&reduced_bucket, node);
 579
 580         if (edge == NULL) {
 581                 edge = alloc_edge(pbqp, src_node->index, tgt_node->index, mat);
 582         } else {
 583                 pbqp_matrix_add(edge->costs, mat);
 584
 585                 /* Free local matrix. */
 586                 obstack_free(&pbqp->obstack, mat);
 587
 588                 reorder_node(src_node);
 589                 reorder_node(tgt_node);
 590         }
 591
 592         if (pbqp->dump_file) {
 593                 fputs("<br>\nAfter reduction:<br>\n", pbqp->dump_file);
 594                 dump_edge(pbqp, edge);
 595         }
 596
 597         /* Edge has changed so we simplify it. */
 598         simplify_edge(pbqp, edge);
 599 }
 600
 601 void apply_RN(pbqp *pbqp)
 602 {
 603         pbqp_node  **bucket       = node_buckets[3];
 604         unsigned     bucket_len   = node_bucket_get_length(bucket);
 605         unsigned     bucket_index;
 606         pbqp_node   *node         = NULL;
 607         pbqp_edge   *edge;
 608         vector      *node_vec;
 609         vector      *vec;
 610         pbqp_matrix *mat;
 611         unsigned     edge_index;
 612         unsigned     max_degree   = 0;
 613         unsigned     node_index;
 614         unsigned     node_len;
 615         unsigned     min_index    = 0;
 616         num          min          = INF_COSTS;
 617         int          is_src;
 618
 619         assert(pbqp);
 620
 621         /* Search for node with maximum degree. */
 622         for (bucket_index = 0; bucket_index < bucket_len; ++bucket_index) {
 623                 pbqp_node *candidate = bucket[bucket_index];
 624                 unsigned   degree    = ARR_LEN(candidate->edges);
 625
 626                 if (degree > max_degree) {
 627                         node = candidate;
 628                         max_degree = degree;
 629                 }
 630         }
 631         assert(node);
 632         node_vec = node->costs;
 633         node_len = node_vec->len;
 634
 635         if (pbqp->dump_file) {
 636                 char     txt[100];
 637                 sprintf(txt, "RN-Reduction of Node n%d", node->index);
 638                 dump_section(pbqp->dump_file, 2, txt);
 639                 pbqp_dump_graph(pbqp);
 640         }
 641
 642         for (node_index = 0; node_index < node_len; ++node_index) {
 643                 num value = node_vec->entries[node_index].data;
 644
 645                 for (edge_index = 0; edge_index < max_degree; ++edge_index) {
 646                         edge   = node->edges[edge_index];
 647                         mat    = edge->costs;
 648                         is_src = edge->src == node;
 649
 650                         if (is_src) {
 651                                 vec = vector_copy(pbqp, edge->tgt->costs);
 652                                 vector_add_matrix_row(vec, mat, node_index);
 653                         } else {
 654                                 vec = vector_copy(pbqp, edge->src->costs);
 655                                 vector_add_matrix_col(vec, mat, node_index);
 656                         }
 657
 658                         value = pbqp_add(value, vector_get_min(vec));
 659
 660                         obstack_free(&pbqp->obstack, vec);
 661                 }
 662
 663                 if (value < min) {
 664                         min = value;
 665                         min_index = node_index;
 666                 }
 667         }
 668
 669         if (pbqp->dump_file) {
 670                 fprintf(pbqp->dump_file, "node n%d is set to %d<br><br>\n",
 671                                         node->index, min_index);
 672                 fprintf(pbqp->dump_file, "Minimal cost of RN reduction: %lld<br>\n",
 673                                                         min);
 674         }
 675
 676         node->solution = min_index;
 677
 678         /* Now that we found the local minimum set all other costs to infinity. */
 679         for (node_index = 0; node_index < node_len; ++node_index) {
 680                 if (node_index != min_index) {
 681                         node_vec->entries[node_index].data = INF_COSTS;
 682                 }
 683         }
 684
 685         /* Add all incident edges to edge bucket, since they are now independent. */
 686         for (edge_index = 0; edge_index < max_degree; ++edge_index) {
 687                 insert_into_edge_bucket(node->edges[edge_index]);
 688         }
 689 }
 690
 691 void back_propagate_RI(pbqp *pbqp, pbqp_node *node)
 692 {
 693         pbqp_edge   *edge;
 694         pbqp_node   *other;
 695         pbqp_matrix *mat;
 696         vector      *vec;
 697         int          is_src;
 698
 699         assert(pbqp);
 700         assert(node);
 701
 702         edge = node->edges[0];
 703         mat = edge->costs;
 704         is_src = edge->src == node;
 705         vec = node->costs;
 706
 707         if (is_src) {
 708                 other = edge->tgt;
 709                 assert(other);
 710                 vector_add_matrix_col(vec, mat, other->solution);
 711         } else {
 712                 other = edge->src;
 713                 assert(other);
 714                 vector_add_matrix_row(vec, mat, other->solution);
 715         }
 716
 717         node->solution = vector_get_min_index(vec);
 718         if (pbqp->dump_file) {
 719                 fprintf(pbqp->dump_file, "node n%d is set to %d<br>\n", node->index, node->solution);
 720         }
 721 }
 722
 723 void back_propagate_RII(pbqp *pbqp, pbqp_node *node)
 724 {
 725         pbqp_edge   *src_edge   = node->edges[0];
 726         pbqp_edge   *tgt_edge   = node->edges[1];
 727         int          src_is_src = src_edge->src == node;
 728         int          tgt_is_src = tgt_edge->src == node;
 729         pbqp_matrix *src_mat;
 730         pbqp_matrix *tgt_mat;
 731         pbqp_node   *src_node;
 732         pbqp_node   *tgt_node;
 733         vector      *vec;
 734         vector      *node_vec;
 735         unsigned     col_index;
 736         unsigned     row_index;
 737
 738         assert(pbqp);
 739
 740         if (src_is_src) {
 741                 src_node = src_edge->tgt;
 742         } else {
 743                 src_node = src_edge->src;
 744         }
 745
 746         if (tgt_is_src) {
 747                 tgt_node = tgt_edge->tgt;
 748         } else {
 749                 tgt_node = tgt_edge->src;
 750         }
 751
 752         /* Swap nodes if necessary. */
 753         if (tgt_node->index < src_node->index) {
 754                 pbqp_node *tmp_node;
 755                 pbqp_edge *tmp_edge;
 756
 757                 tmp_node = src_node;
 758                 src_node = tgt_node;
 759                 tgt_node = tmp_node;
 760
 761                 tmp_edge = src_edge;
 762                 src_edge = tgt_edge;
 763                 tgt_edge = tmp_edge;
 764
 765                 src_is_src = src_edge->src == node;
 766                 tgt_is_src = tgt_edge->src == node;
 767         }
 768
 769         src_mat = src_edge->costs;
 770         tgt_mat = tgt_edge->costs;
 771
 772         node_vec = node->costs;
 773
 774         row_index = src_node->solution;
 775         col_index = tgt_node->solution;
 776
 777         vec = vector_copy(pbqp, node_vec);
 778
 779         if (src_is_src) {
 780                 vector_add_matrix_col(vec, src_mat, row_index);
 781         } else {
 782                 vector_add_matrix_row(vec, src_mat, row_index);
 783         }
 784
 785         if (tgt_is_src) {
 786                 vector_add_matrix_col(vec, tgt_mat, col_index);
 787         } else {
 788                 vector_add_matrix_row(vec, tgt_mat, col_index);
 789         }
 790
 791         node->solution = vector_get_min_index(vec);
 792         if (pbqp->dump_file) {
 793                 fprintf(pbqp->dump_file, "node n%d is set to %d<br>\n", node->index, node->solution);
 794         }
 795
 796         obstack_free(&pbqp->obstack, vec);
 797 }
 798
 799 int node_is_reduced(pbqp_node *node)
 800 {
 801         if (!reduced_bucket) return 0;
 802
 803         assert(node);
 804         if (ARR_LEN(node->edges) == 0) return 1;
 805
 806         return node_bucket_contains(reduced_bucket, node);
 807 }