Use other mechanism to determine whether an edge is already copied or not.
[libfirm] / heuristical.c
index cbc61e0..2ee5170 100644 (file)
@@ -2,6 +2,7 @@
 #include "assert.h"
 #include "error.h"
 
+#include "bucket.h"
 #include "heuristical.h"
 #include "html_dumper.h"
 #include "kaps.h"
@@ -17,28 +18,28 @@ static pbqp_node **node_buckets[4];
 static pbqp_node **reduced_bucket = NULL;
 static int         buckets_filled = 0;
 
+/* Forward declarations. */
+static void apply_Brute_Force(pbqp *pbqp);
+
 static void insert_into_edge_bucket(pbqp_edge *edge)
 {
-       unsigned bucket_len = ARR_LEN(edge_bucket);
-
-       if (edge->bucket_index < bucket_len && edge_bucket[edge->bucket_index]
-                       == edge)
+       if (edge_bucket_contains(edge_bucket, edge)) {
                /* Edge is already inserted. */
                return;
+       }
 
-       edge->bucket_index = bucket_len;
-       ARR_APP1(pbqp_edge *, edge_bucket, edge);
+       edge_bucket_insert(&edge_bucket, edge);
 }
 
 static void init_buckets(void)
 {
        int i;
 
-       edge_bucket = NEW_ARR_F(pbqp_edge *, 0);
-       reduced_bucket = NEW_ARR_F(pbqp_node *, 0);
+       edge_bucket_init(&edge_bucket);
+       node_bucket_init(&reduced_bucket);
 
        for (i = 0; i < 4; ++i) {
-               node_buckets[i] = NEW_ARR_F(pbqp_node *, 0);
+               node_bucket_init(&node_buckets[i]);
        }
 }
 
@@ -47,15 +48,11 @@ static void free_buckets(void)
        int i;
 
        for (i = 0; i < 4; ++i) {
-               DEL_ARR_F(node_buckets[i]);
-               node_buckets[i] = NULL;
+               node_bucket_free(&node_buckets[i]);
        }
 
-       DEL_ARR_F(edge_bucket);
-       edge_bucket = NULL;
-
-       DEL_ARR_F(reduced_bucket);
-       reduced_bucket = NULL;
+       edge_bucket_free(&edge_bucket);
+       node_bucket_free(&reduced_bucket);
 
        buckets_filled = 0;
 }
@@ -69,21 +66,19 @@ static void fill_node_buckets(pbqp *pbqp)
        node_len = pbqp->num_nodes;
 
        for (node_index = 0; node_index < node_len; ++node_index) {
-               unsigned   arity;
+               unsigned   degree;
                pbqp_node *node = get_node(pbqp, node_index);
 
                if (!node) continue;
 
-               arity = ARR_LEN(node->edges);
+               degree = pbqp_node_get_degree(node);
 
                /* We have only one bucket for nodes with arity >= 3. */
-               if (arity > 3) {
-                       arity = 3;
+               if (degree > 3) {
+                       degree = 3;
                }
 
-               node->bucket_index = ARR_LEN(node_buckets[arity]);
-
-               ARR_APP1(pbqp_node *, node_buckets[arity], node);
+               node_bucket_insert(&node_buckets[degree], node);
        }
 
        buckets_filled = 1;
@@ -136,7 +131,7 @@ static void normalize_towards_source(pbqp *pbqp, pbqp_edge *edge)
 
                        if (min == INF_COSTS) {
                                unsigned edge_index;
-                               unsigned edge_len = ARR_LEN(src_node->edges);
+                               unsigned edge_len = pbqp_node_get_degree(src_node);
 
                                for (edge_index = 0; edge_index < edge_len; ++edge_index) {
                                        pbqp_edge *edge_candidate = src_node->edges[edge_index];
@@ -195,7 +190,7 @@ static void normalize_towards_target(pbqp *pbqp, pbqp_edge *edge)
 
                        if (min == INF_COSTS) {
                                unsigned edge_index;
-                               unsigned edge_len = ARR_LEN(tgt_node->edges);
+                               unsigned edge_len = pbqp_node_get_degree(tgt_node);
 
                                for (edge_index = 0; edge_index < edge_len; ++edge_index) {
                                        pbqp_edge *edge_candidate = tgt_node->edges[edge_index];
@@ -210,49 +205,124 @@ static void normalize_towards_target(pbqp *pbqp, pbqp_edge *edge)
 
 static void reorder_node(pbqp_node *node)
 {
-       unsigned    arity;
-       unsigned    old_arity;
-       unsigned    old_bucket_len;
-       unsigned    old_bucket_index;
-       pbqp_node **old_bucket;
-       pbqp_node  *other;
+       unsigned    degree     = pbqp_node_get_degree(node);
+       /* Assume node lost one incident edge. */
+       unsigned    old_degree = degree + 1;
 
        if (!buckets_filled) return;
 
-       assert(node);
-
-       arity = ARR_LEN(node->edges);
-
        /* Same bucket as before */
-       if (arity > 2) return;
-
-       /* Assume node lost one incident edge. */
-       old_arity        = arity + 1;
-       old_bucket       = node_buckets[old_arity];
-       old_bucket_len   = ARR_LEN(old_bucket);
-       old_bucket_index = node->bucket_index;
-
-       if (old_bucket_len <= old_bucket_index || old_bucket[old_bucket_index]
-                       != node) {
-               unsigned bucket_len = ARR_LEN(node_buckets[arity]);
+       if (degree > 2) return;
 
+       if (!node_bucket_contains(node_buckets[old_degree], node)) {
                /* Old arity is new arity, so we have nothing to do. */
-               assert(old_bucket_index < bucket_len);
-               assert(node_buckets[arity][old_bucket_index] == node);
+               assert(node_bucket_contains(node_buckets[degree], node));
                return;
        }
 
-       assert(old_bucket[old_bucket_index] == node);
-
        /* Delete node from old bucket... */
-       other                        = old_bucket[old_bucket_len - 1];
-       other->bucket_index          = old_bucket_index;
-       old_bucket[old_bucket_index] = other;
-       ARR_SHRINKLEN(node_buckets[old_arity], old_bucket_len - 1);
+       node_bucket_remove(&node_buckets[old_degree], node);
 
        /* ..and add to new one. */
-       node->bucket_index = ARR_LEN(node_buckets[arity]);
-       ARR_APP1(pbqp_node*, node_buckets[arity], node);
+       node_bucket_insert(&node_buckets[degree], node);
+}
+
+static void check_melting_possibility(pbqp *pbqp, pbqp_edge *edge)
+{
+       pbqp_matrix    *mat;
+       pbqp_node      *src_node;
+       pbqp_node      *tgt_node;
+       vector         *src_vec;
+       vector         *tgt_vec;
+       int             src_len;
+       int             tgt_len;
+       int             src_index;
+       int             tgt_index;
+
+       assert(pbqp);
+       assert(edge);
+
+       src_node = edge->src;
+       tgt_node = edge->tgt;
+       assert(src_node);
+       assert(tgt_node);
+
+       src_vec = src_node->costs;
+       tgt_vec = tgt_node->costs;
+       assert(src_vec);
+       assert(tgt_vec);
+
+       src_len = src_vec->len;
+       tgt_len = tgt_vec->len;
+       assert(src_len > 0);
+       assert(tgt_len > 0);
+
+       mat = edge->costs;
+       assert(mat);
+
+       if (src_len == 1 && tgt_len == 1) {
+               //panic("Something is wrong");
+       }
+
+       int allRowsOk = 1;
+       for (src_index = 0; src_index < src_len; ++src_index) {
+               int onlyOneZero = 0;
+               if (src_vec->entries[src_index].data == INF_COSTS) {
+                       continue;
+               }
+               for (tgt_index = 0; tgt_index < tgt_len; ++tgt_index) {
+                       if (tgt_vec->entries[tgt_index].data == INF_COSTS) {
+                               continue;
+                       }
+                       if (mat->entries[src_index * tgt_len + tgt_index] == 0) {
+                               if (onlyOneZero) {
+                                       onlyOneZero = 0;
+                                       break;
+                               } else {
+                                       onlyOneZero = 1;
+                                       continue;
+                               }
+                       }
+                       if (mat->entries[src_index * tgt_len + tgt_index] == INF_COSTS) {
+                               continue;
+                       }
+                       onlyOneZero = 0;
+                       break;
+               }
+               allRowsOk &= onlyOneZero;
+       }
+
+       int allColsOk = 1;
+       for (tgt_index = 0; tgt_index < tgt_len; ++tgt_index) {
+               int onlyOneZero = 0;
+               if (tgt_vec->entries[tgt_index].data == INF_COSTS) {
+                       continue;
+               }
+               for (src_index = 0; src_index < src_len; ++src_index) {
+                       if (src_vec->entries[src_index].data == INF_COSTS) {
+                               continue;
+                       }
+                       if (mat->entries[src_index * tgt_len + tgt_index] == 0) {
+                               if (onlyOneZero) {
+                                       onlyOneZero = 0;
+                                       break;
+                               } else {
+                                       onlyOneZero = 1;
+                                       continue;
+                               }
+                       }
+                       if (mat->entries[src_index * tgt_len + tgt_index] == INF_COSTS) {
+                               continue;
+                       }
+                       onlyOneZero = 0;
+                       break;
+               }
+               allColsOk &= onlyOneZero;
+       }
+
+       if (allRowsOk && allColsOk) {
+               panic("Hurray");
+       }
 }
 
 static void simplify_edge(pbqp *pbqp, pbqp_edge *edge)
@@ -317,10 +387,12 @@ static void simplify_edge(pbqp *pbqp, pbqp_edge *edge)
                delete_edge(edge);
                reorder_node(src_node);
                reorder_node(tgt_node);
+       } else {
+               //check_melting_possibility(pbqp, edge);
        }
 }
 
-void solve_pbqp_heuristical(pbqp *pbqp)
+static void initial_simplify_edges(pbqp *pbqp)
 {
        unsigned node_index;
        unsigned node_len;
@@ -346,7 +418,7 @@ void solve_pbqp_heuristical(pbqp *pbqp)
                if (!node) continue;
 
                edges = node->edges;
-               edge_len = ARR_LEN(edges);
+               edge_len = pbqp_node_get_degree(node);
 
                for (edge_index = 0; edge_index < edge_len; ++edge_index) {
                        pbqp_edge *edge = edges[edge_index];
@@ -357,57 +429,56 @@ void solve_pbqp_heuristical(pbqp *pbqp)
                        simplify_edge(pbqp, edge);
                }
        }
+}
 
-       /* Put node into bucket representing their arity. */
-       fill_node_buckets(pbqp);
-
-       for (;;) {
-               if (ARR_LEN(edge_bucket) > 0) {
-                       apply_edge(pbqp);
-               } else if (ARR_LEN(node_buckets[1]) > 0) {
-                       apply_RI(pbqp);
-               } else if (ARR_LEN(node_buckets[2]) > 0) {
-                       apply_RII(pbqp);
-               } else if (ARR_LEN(node_buckets[3]) > 0) {
-                       apply_RN(pbqp);
-               } else {
-                       break;
-               }
-       }
+num determine_solution(FILE *file)
+{
+       unsigned node_index;
+       unsigned node_len;
+       num      solution;
 
-       if (pbqp->dump_file) {
-               dump_section(pbqp->dump_file, 1, "4. Determine Solution/Minimum");
-               dump_section(pbqp->dump_file, 2, "4.1. Trivial Solution");
+       if (file) {
+               dump_section(file, 1, "4. Determine Solution/Minimum");
+               dump_section(file, 2, "4.1. Trivial Solution");
        }
 
        /* Solve trivial nodes and calculate solution. */
-       node_len = ARR_LEN(node_buckets[0]);
+       node_len = node_bucket_get_length(node_buckets[0]);
        for (node_index = 0; node_index < node_len; ++node_index) {
                pbqp_node *node = node_buckets[0][node_index];
                assert(node);
 
                node->solution = vector_get_min_index(node->costs);
-               pbqp->solution = pbqp_add(pbqp->solution,
+               solution       = pbqp_add(solution,
                                node->costs->entries[node->solution].data);
-               if (pbqp->dump_file) {
-                       fprintf(pbqp->dump_file, "node n%d is set to %d<br>\n", node->index, node->solution);
-                       dump_node(pbqp, node);
+               if (file) {
+                       fprintf(file, "node n%d is set to %d<br>\n", node->index, node->solution);
+                       dump_node(file, node);
                }
        }
 
+       if (file) {
+               dump_section(file, 2, "Minimum");
+               fprintf(file, "Minimum is equal to %lld.", solution);
+       }
+
+       return solution;
+}
+
+static void back_propagate(pbqp *pbqp)
+{
+       unsigned node_index;
+       unsigned node_len   = node_bucket_get_length(reduced_bucket);
+
+       assert(pbqp);
        if (pbqp->dump_file) {
-               dump_section(pbqp->dump_file, 2, "Minimum");
-               fprintf(pbqp->dump_file, "Minimum is equal to %lld.", pbqp->solution);
                dump_section(pbqp->dump_file, 2, "Back Propagation");
        }
 
-       /* Solve reduced nodes. */
-       node_len = ARR_LEN(reduced_bucket);
        for (node_index = node_len; node_index > 0; --node_index) {
                pbqp_node *node = reduced_bucket[node_index - 1];
-               assert(node);
 
-               switch (ARR_LEN(node->edges)) {
+               switch (pbqp_node_get_degree(node)) {
                        case 1:
                                back_propagate_RI(pbqp, node);
                                break;
@@ -419,30 +490,60 @@ void solve_pbqp_heuristical(pbqp *pbqp)
                                break;
                }
        }
+}
+
+static void apply_heuristic_reductions(pbqp *pbqp)
+{
+       for (;;) {
+               if (edge_bucket_get_length(edge_bucket) > 0) {
+                       apply_edge(pbqp);
+               } else if (node_bucket_get_length(node_buckets[1]) > 0) {
+                       apply_RI(pbqp);
+               } else if (node_bucket_get_length(node_buckets[2]) > 0) {
+                       apply_RII(pbqp);
+               } else if (node_bucket_get_length(node_buckets[3]) > 0) {
+                       apply_RN(pbqp);
+               } else {
+                       return;
+               }
+       }
+}
+
+void solve_pbqp_heuristical(pbqp *pbqp)
+{
+       /* Reduce nodes degree ... */
+       initial_simplify_edges(pbqp);
+
+       /* ... and put node into bucket representing their degree. */
+       fill_node_buckets(pbqp);
+
+       apply_heuristic_reductions(pbqp);
+
+       pbqp->solution = determine_solution(pbqp->dump_file);
+
+       /* Solve reduced nodes. */
+       back_propagate(pbqp);
 
        free_buckets();
 }
 
 void apply_edge(pbqp *pbqp)
 {
-       unsigned   bucket_len = ARR_LEN(edge_bucket);
-       pbqp_edge *edge       = edge_bucket[bucket_len - 1];
-
-       ARR_SHRINKLEN(edge_bucket, (int)bucket_len - 1);
+       pbqp_edge *edge = edge_bucket_pop(&edge_bucket);
 
        simplify_edge(pbqp, edge);
 }
 
 void apply_RI(pbqp *pbqp)
 {
-       pbqp_node  **bucket     = node_buckets[1];
-       unsigned     bucket_len = ARR_LEN(bucket);
-       pbqp_node   *node       = bucket[bucket_len - 1];
+       pbqp_node   *node       = node_bucket_pop(&node_buckets[1]);
        pbqp_edge   *edge       = node->edges[0];
        pbqp_matrix *mat        = edge->costs;
        int          is_src     = edge->src == node;
        pbqp_node   *other_node;
 
+       assert(pbqp_node_get_degree(node) == 1);
+
        if (is_src) {
                other_node = edge->tgt;
        } else {
@@ -455,9 +556,9 @@ void apply_RI(pbqp *pbqp)
                dump_section(pbqp->dump_file, 2, txt);
                pbqp_dump_graph(pbqp);
                fputs("<br>\nBefore reduction:<br>\n", pbqp->dump_file);
-               dump_node(pbqp, node);
-               dump_node(pbqp, other_node);
-               dump_edge(pbqp, edge);
+               dump_node(pbqp->dump_file, node);
+               dump_node(pbqp->dump_file, other_node);
+               dump_edge(pbqp->dump_file, edge);
        }
 
        if (is_src) {
@@ -471,23 +572,18 @@ void apply_RI(pbqp *pbqp)
 
        if (pbqp->dump_file) {
                fputs("<br>\nAfter reduction:<br>\n", pbqp->dump_file);
-               dump_node(pbqp, other_node);
+               dump_node(pbqp->dump_file, other_node);
        }
 
-       /* Remove node from bucket... */
-       ARR_SHRINKLEN(bucket, (int)bucket_len - 1);
        reorder_node(other_node);
 
-       /* ...and add it to back propagation list. */
-       node->bucket_index = ARR_LEN(reduced_bucket);
-       ARR_APP1(pbqp_node *, reduced_bucket, node);
+       /* Add node to back propagation list. */
+       node_bucket_insert(&reduced_bucket, node);
 }
 
 void apply_RII(pbqp *pbqp)
 {
-       pbqp_node  **bucket     = node_buckets[2];
-       unsigned     bucket_len = ARR_LEN(bucket);
-       pbqp_node   *node       = bucket[bucket_len - 1];
+       pbqp_node   *node       = node_bucket_pop(&node_buckets[2]);
        pbqp_edge   *src_edge   = node->edges[0];
        pbqp_edge   *tgt_edge   = node->edges[1];
        int          src_is_src = src_edge->src == node;
@@ -508,6 +604,7 @@ void apply_RII(pbqp *pbqp)
        unsigned     node_len;
 
        assert(pbqp);
+       assert(pbqp_node_get_degree(node) == 2);
 
        if (src_is_src) {
                src_node = src_edge->tgt;
@@ -544,11 +641,11 @@ void apply_RII(pbqp *pbqp)
                dump_section(pbqp->dump_file, 2, txt);
                pbqp_dump_graph(pbqp);
                fputs("<br>\nBefore reduction:<br>\n", pbqp->dump_file);
-               dump_node(pbqp, src_node);
-               dump_edge(pbqp, src_edge);
-               dump_node(pbqp, node);
-               dump_edge(pbqp, tgt_edge);
-               dump_node(pbqp, tgt_node);
+               dump_node(pbqp->dump_file, src_node);
+               dump_edge(pbqp->dump_file, src_edge);
+               dump_node(pbqp->dump_file, node);
+               dump_edge(pbqp->dump_file, tgt_edge);
+               dump_node(pbqp->dump_file, tgt_node);
        }
 
        src_mat = src_edge->costs;
@@ -592,12 +689,8 @@ void apply_RII(pbqp *pbqp)
        disconnect_edge(src_node, src_edge);
        disconnect_edge(tgt_node, tgt_edge);
 
-       /* Remove node from bucket... */
-       ARR_SHRINKLEN(bucket, (int)bucket_len - 1);
-
-       /* ...and add it to back propagation list. */
-       node->bucket_index = ARR_LEN(reduced_bucket);
-       ARR_APP1(pbqp_node *, reduced_bucket, node);
+       /* Add node to back propagation list. */
+       node_bucket_insert(&reduced_bucket, node);
 
        if (edge == NULL) {
                edge = alloc_edge(pbqp, src_node->index, tgt_node->index, mat);
@@ -613,19 +706,63 @@ void apply_RII(pbqp *pbqp)
 
        if (pbqp->dump_file) {
                fputs("<br>\nAfter reduction:<br>\n", pbqp->dump_file);
-               dump_edge(pbqp, edge);
+               dump_edge(pbqp->dump_file, edge);
        }
 
        /* Edge has changed so we simplify it. */
        simplify_edge(pbqp, edge);
 }
 
-void apply_RN(pbqp *pbqp)
+static void select_alternative(pbqp_node *node, unsigned selected_index)
+{
+       unsigned  edge_index;
+       unsigned  node_index;
+       unsigned  node_len;
+       vector   *node_vec;
+       unsigned  max_degree = pbqp_node_get_degree(node);
+
+       assert(node);
+       node->solution = selected_index;
+       node_vec = node->costs;
+       node_len = node_vec->len;
+       assert(selected_index < node_len);
+
+       /* Set all other costs to infinity. */
+       for (node_index = 0; node_index < node_len; ++node_index) {
+               if (node_index != selected_index) {
+                       node_vec->entries[node_index].data = INF_COSTS;
+               }
+       }
+
+       /* Add all incident edges to edge bucket, since they are now independent. */
+       for (edge_index = 0; edge_index < max_degree; ++edge_index) {
+               insert_into_edge_bucket(node->edges[edge_index]);
+       }
+}
+
+static pbqp_node *get_node_with_max_degree(void)
 {
        pbqp_node  **bucket       = node_buckets[3];
-       unsigned     bucket_len   = ARR_LEN(bucket);
+       unsigned     bucket_len   = node_bucket_get_length(bucket);
        unsigned     bucket_index;
-       pbqp_node   *node         = NULL;
+       unsigned     max_degree   = 0;
+       pbqp_node   *result       = NULL;
+
+       for (bucket_index = 0; bucket_index < bucket_len; ++bucket_index) {
+               pbqp_node *candidate = bucket[bucket_index];
+               unsigned   degree    = pbqp_node_get_degree(candidate);
+
+               if (degree > max_degree) {
+                       result = candidate;
+                       max_degree = degree;
+               }
+       }
+
+       return result;
+}
+
+static unsigned get_local_minimal_alternative(pbqp *pbqp, pbqp_node *node)
+{
        pbqp_edge   *edge;
        vector      *node_vec;
        vector      *vec;
@@ -639,28 +776,10 @@ void apply_RN(pbqp *pbqp)
        int          is_src;
 
        assert(pbqp);
-
-       /* Search for node with maximum degree. */
-       for (bucket_index = 0; bucket_index < bucket_len; ++bucket_index) {
-               pbqp_node *candidate = bucket[bucket_index];
-               unsigned   degree    = ARR_LEN(candidate->edges);
-
-               if (degree > max_degree) {
-                       node = candidate;
-                       max_degree = degree;
-               }
-       }
        assert(node);
        node_vec = node->costs;
        node_len = node_vec->len;
 
-       if (pbqp->dump_file) {
-               char     txt[100];
-               sprintf(txt, "RN-Reduction of Node n%d", node->index);
-               dump_section(pbqp->dump_file, 2, txt);
-               pbqp_dump_graph(pbqp);
-       }
-
        for (node_index = 0; node_index < node_len; ++node_index) {
                num value = node_vec->entries[node_index].data;
 
@@ -688,26 +807,167 @@ void apply_RN(pbqp *pbqp)
                }
        }
 
+       return min_index;
+}
+
+void apply_RN(pbqp *pbqp)
+{
+       pbqp_node   *node         = NULL;
+       unsigned     min_index    = 0;
+
+       assert(pbqp);
+
+       /* We want to reduce a node with maximum degree. */
+       node = get_node_with_max_degree();
+       assert(node);
+       assert(pbqp_node_get_degree(node) > 2);
+
+       if (pbqp->dump_file) {
+               char     txt[100];
+               sprintf(txt, "RN-Reduction of Node n%d", node->index);
+               dump_section(pbqp->dump_file, 2, txt);
+               pbqp_dump_graph(pbqp);
+       }
+
+       min_index = get_local_minimal_alternative(pbqp, node);
+
        if (pbqp->dump_file) {
                fprintf(pbqp->dump_file, "node n%d is set to %d<br><br>\n",
                                        node->index, min_index);
-               fprintf(pbqp->dump_file, "Minimal cost of RN reduction: %lld<br>\n",
-                                                       min);
        }
 
-       node->solution = min_index;
-
        /* Now that we found the local minimum set all other costs to infinity. */
+       select_alternative(node, min_index);
+}
+
+static void apply_brute_force_reductions(pbqp *pbqp)
+{
+       for (;;) {
+               if (edge_bucket_get_length(edge_bucket) > 0) {
+                       apply_edge(pbqp);
+               } else if (node_bucket_get_length(node_buckets[1]) > 0) {
+                       apply_RI(pbqp);
+               } else if (node_bucket_get_length(node_buckets[2]) > 0) {
+                       apply_RII(pbqp);
+               } else if (node_bucket_get_length(node_buckets[3]) > 0) {
+                       apply_Brute_Force(pbqp);
+               } else {
+                       return;
+               }
+       }
+}
+
+static unsigned get_minimal_alternative(pbqp *pbqp, pbqp_node *node)
+{
+       vector      *node_vec;
+       unsigned     node_index;
+       unsigned     node_len;
+       unsigned     min_index    = 0;
+       num          min          = INF_COSTS;
+       unsigned     bucket_index;
+
+       assert(pbqp);
+       assert(node);
+       node_vec     = node->costs;
+       node_len     = node_vec->len;
+       bucket_index = node->bucket_index;
+
        for (node_index = 0; node_index < node_len; ++node_index) {
-               if (node_index != min_index) {
-                       node_vec->entries[node_index].data = INF_COSTS;
+               pbqp_node_bucket bucket_deg3;
+               num              value;
+               unsigned         bucket_0_length;
+               unsigned         bucket_red_length;
+
+               /* Some node buckets and the edge bucket should be empty. */
+               assert(node_bucket_get_length(node_buckets[1]) == 0);
+               assert(node_bucket_get_length(node_buckets[2]) == 0);
+               assert(edge_bucket_get_length(edge_bucket)     == 0);
+
+               /* char *tmp = obstack_finish(&pbqp->obstack); */
+
+               /* Save current PBQP state. */
+               node_bucket_deep_copy(pbqp, &bucket_deg3, node_buckets[3]);
+               bucket_0_length   = node_bucket_get_length(node_buckets[0]);
+               bucket_red_length = node_bucket_get_length(reduced_bucket);
+
+               /* Select alternative and solve PBQP recursively. */
+               select_alternative(node_buckets[3][bucket_index], node_index);
+               apply_brute_force_reductions(pbqp);
+
+               value = determine_solution(pbqp->dump_file);
+
+               if (value < min) {
+                       min = value;
+                       min_index = node_index;
                }
+
+               /* Some node buckets and the edge bucket should still be empty. */
+               assert(node_bucket_get_length(node_buckets[1]) == 0);
+               assert(node_bucket_get_length(node_buckets[2]) == 0);
+               assert(edge_bucket_get_length(edge_bucket)     == 0);
+
+               /* Clear modified buckets... */
+               node_bucket_shrink(&node_buckets[3], 0);
+
+               /* ... and restore old PBQP state. */
+               node_bucket_shrink(&node_buckets[0], bucket_0_length);
+               node_bucket_shrink(&reduced_bucket, bucket_red_length);
+               node_bucket_copy(&node_buckets[3], bucket_deg3);
+
+               /* Free copies. */
+               /* obstack_free(&pbqp->obstack, tmp); */
+               node_bucket_free(&bucket_deg3);
        }
 
-       /* Add all incident edges to edge bucket, since they are now independent. */
-       for (edge_index = 0; edge_index < max_degree; ++edge_index) {
-               insert_into_edge_bucket(node->edges[edge_index]);
+       return min_index;
+}
+
+void apply_Brute_Force(pbqp *pbqp)
+{
+       pbqp_node   *node         = NULL;
+       unsigned     min_index    = 0;
+
+       assert(pbqp);
+
+       /* We want to reduce a node with maximum degree. */
+       node = get_node_with_max_degree();
+       assert(node);
+       assert(pbqp_node_get_degree(node) > 2);
+
+       if (pbqp->dump_file) {
+               char     txt[100];
+               sprintf(txt, "BF-Reduction of Node n%d", node->index);
+               dump_section(pbqp->dump_file, 2, txt);
+               pbqp_dump_graph(pbqp);
        }
+
+       min_index = get_minimal_alternative(pbqp, node);
+
+       if (pbqp->dump_file) {
+               fprintf(pbqp->dump_file, "node n%d is set to %d<br><br>\n",
+                                       node->index, min_index);
+       }
+
+       /* Now that we found the minimum set all other costs to infinity. */
+       select_alternative(node, min_index);
+}
+
+void solve_pbqp_brute_force(pbqp *pbqp)
+{
+       /* Reduce nodes degree ... */
+       initial_simplify_edges(pbqp);
+
+       /* ... and put node into bucket representing their degree. */
+       fill_node_buckets(pbqp);
+
+       apply_brute_force_reductions(pbqp);
+
+       pbqp->solution = determine_solution(pbqp->dump_file);
+
+       /* Solve reduced nodes. */
+       back_propagate(pbqp);
+
+       free_buckets();
 }
 
 void back_propagate_RI(pbqp *pbqp, pbqp_node *node)
@@ -822,11 +1082,7 @@ int node_is_reduced(pbqp_node *node)
 {
        if (!reduced_bucket) return 0;
 
-       assert(node);
-       if (ARR_LEN(node->edges) == 0) return 1;
-
-       unsigned bucket_length = ARR_LEN(reduced_bucket);
-       unsigned bucket_index  = node->bucket_index;
+       if (pbqp_node_get_degree(node) == 0) return 1;
 
-       return bucket_index < bucket_length && reduced_bucket[bucket_index] == node;
+       return node_bucket_contains(reduced_bucket, node);
 }