X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=heuristical.c;h=2ee5170baae1406f870504bf89ff023991f199ec;hb=9bbf4d07cd3b5c39acf50470bd10f5e738612996;hp=e69de29bb2d1d6434b8b29ae775ad8c2e48c5391;hpb=d01193ed5f4474a0f51b2b8dd809f5b39ac9b722;p=libfirm
diff --git a/heuristical.c b/heuristical.c
index e69de29bb..2ee5170ba 100644
--- a/heuristical.c
+++ b/heuristical.c
@@ -0,0 +1,1088 @@
+#include "adt/array.h"
+#include "assert.h"
+#include "error.h"
+
+#include "bucket.h"
+#include "heuristical.h"
+#include "html_dumper.h"
+#include "kaps.h"
+#include "matrix.h"
+#include "pbqp_edge.h"
+#include "pbqp_edge_t.h"
+#include "pbqp_node.h"
+#include "pbqp_node_t.h"
+#include "vector.h"
+
+static pbqp_edge **edge_bucket;
+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)
+{
+ if (edge_bucket_contains(edge_bucket, edge)) {
+ /* Edge is already inserted. */
+ return;
+ }
+
+ edge_bucket_insert(&edge_bucket, edge);
+}
+
+static void init_buckets(void)
+{
+ int i;
+
+ edge_bucket_init(&edge_bucket);
+ node_bucket_init(&reduced_bucket);
+
+ for (i = 0; i < 4; ++i) {
+ node_bucket_init(&node_buckets[i]);
+ }
+}
+
+static void free_buckets(void)
+{
+ int i;
+
+ for (i = 0; i < 4; ++i) {
+ node_bucket_free(&node_buckets[i]);
+ }
+
+ edge_bucket_free(&edge_bucket);
+ node_bucket_free(&reduced_bucket);
+
+ buckets_filled = 0;
+}
+
+static void fill_node_buckets(pbqp *pbqp)
+{
+ unsigned node_index;
+ unsigned node_len;
+
+ assert(pbqp);
+ node_len = pbqp->num_nodes;
+
+ for (node_index = 0; node_index < node_len; ++node_index) {
+ unsigned degree;
+ pbqp_node *node = get_node(pbqp, node_index);
+
+ if (!node) continue;
+
+ degree = pbqp_node_get_degree(node);
+
+ /* We have only one bucket for nodes with arity >= 3. */
+ if (degree > 3) {
+ degree = 3;
+ }
+
+ node_bucket_insert(&node_buckets[degree], node);
+ }
+
+ buckets_filled = 1;
+}
+
+static void normalize_towards_source(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;
+
+ 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);
+
+ /* Normalize towards source node. */
+ for (src_index = 0; src_index < src_len; ++src_index) {
+ num min = pbqp_matrix_get_row_min(mat, src_index, tgt_vec);
+
+ if (min != 0) {
+ if (src_vec->entries[src_index].data == INF_COSTS) {
+ pbqp_matrix_set_row_value(mat, src_index, 0);
+ } else {
+ pbqp_matrix_sub_row_value(mat, src_index, tgt_vec, min);
+ }
+ src_vec->entries[src_index].data = pbqp_add(
+ src_vec->entries[src_index].data, min);
+
+ if (min == INF_COSTS) {
+ unsigned edge_index;
+ 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];
+ if (edge_candidate != edge) {
+ insert_into_edge_bucket(edge_candidate);
+ }
+ }
+ }
+ }
+ }
+}
+
+static void normalize_towards_target(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 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);
+
+ for (tgt_index = 0; tgt_index < tgt_len; ++tgt_index) {
+ num min = pbqp_matrix_get_col_min(mat, tgt_index, src_vec);
+
+ if (min != 0) {
+ if (tgt_vec->entries[tgt_index].data == INF_COSTS) {
+ pbqp_matrix_set_col_value(mat, tgt_index, 0);
+ } else {
+ pbqp_matrix_sub_col_value(mat, tgt_index, src_vec, min);
+ }
+ tgt_vec->entries[tgt_index].data = pbqp_add(
+ tgt_vec->entries[tgt_index].data, min);
+
+ if (min == INF_COSTS) {
+ unsigned edge_index;
+ 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];
+ if (edge_candidate != edge) {
+ insert_into_edge_bucket(edge_candidate);
+ }
+ }
+ }
+ }
+ }
+}
+
+static void reorder_node(pbqp_node *node)
+{
+ unsigned degree = pbqp_node_get_degree(node);
+ /* Assume node lost one incident edge. */
+ unsigned old_degree = degree + 1;
+
+ if (!buckets_filled) return;
+
+ /* Same bucket as before */
+ 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(node_bucket_contains(node_buckets[degree], node));
+ return;
+ }
+
+ /* Delete node from old bucket... */
+ node_bucket_remove(&node_buckets[old_degree], node);
+
+ /* ..and add to new one. */
+ 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)
+{
+ pbqp_matrix *mat;
+ pbqp_node *src_node;
+ pbqp_node *tgt_node;
+ vector *src_vec;
+ vector *tgt_vec;
+ int src_len;
+ int tgt_len;
+
+ assert(pbqp);
+ assert(edge);
+
+ src_node = edge->src;
+ tgt_node = edge->tgt;
+ assert(src_node);
+ assert(tgt_node);
+
+ /* If edge are already deleted, we have nothing to do. */
+ if (!is_connected(src_node, edge) || !is_connected(tgt_node, edge))
+ return;
+
+ if (pbqp->dump_file) {
+ char txt[100];
+ sprintf(txt, "Simplification of Edge n%d-n%d", src_node->index, tgt_node->index);
+ dump_section(pbqp->dump_file, 3, txt);
+ }
+
+ 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 (pbqp->dump_file) {
+ fputs("Input:
\n", pbqp->dump_file);
+ dump_simplifyedge(pbqp, edge);
+ }
+
+ normalize_towards_source(pbqp, edge);
+ normalize_towards_target(pbqp, edge);
+
+ if (pbqp->dump_file) {
+ fputs("
\nOutput:
\n", pbqp->dump_file);
+ dump_simplifyedge(pbqp, edge);
+ }
+
+ if (pbqp_matrix_is_zero(mat, src_vec, tgt_vec)) {
+ if (pbqp->dump_file) {
+ fputs("edge has been eliminated
\n", pbqp->dump_file);
+ }
+
+ delete_edge(edge);
+ reorder_node(src_node);
+ reorder_node(tgt_node);
+ } else {
+ //check_melting_possibility(pbqp, edge);
+ }
+}
+
+static void initial_simplify_edges(pbqp *pbqp)
+{
+ unsigned node_index;
+ unsigned node_len;
+
+ assert(pbqp);
+
+ if (pbqp->dump_file) {
+ pbqp_dump_input(pbqp);
+ dump_section(pbqp->dump_file, 1, "2. Simplification of Cost Matrices");
+ }
+
+ node_len = pbqp->num_nodes;
+
+ init_buckets();
+
+ /* First simplify all edges. */
+ for (node_index = 0; node_index < node_len; ++node_index) {
+ unsigned edge_index;
+ pbqp_node *node = get_node(pbqp, node_index);
+ pbqp_edge **edges;
+ unsigned edge_len;
+
+ if (!node) continue;
+
+ edges = node->edges;
+ edge_len = pbqp_node_get_degree(node);
+
+ for (edge_index = 0; edge_index < edge_len; ++edge_index) {
+ pbqp_edge *edge = edges[edge_index];
+
+ /* Simplify only once per edge. */
+ if (node != edge->src) continue;
+
+ simplify_edge(pbqp, edge);
+ }
+ }
+}
+
+num determine_solution(FILE *file)
+{
+ unsigned node_index;
+ unsigned node_len;
+ num 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 = 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);
+ solution = pbqp_add(solution,
+ node->costs->entries[node->solution].data);
+ if (file) {
+ fprintf(file, "node n%d is set to %d
\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, "Back Propagation");
+ }
+
+ for (node_index = node_len; node_index > 0; --node_index) {
+ pbqp_node *node = reduced_bucket[node_index - 1];
+
+ switch (pbqp_node_get_degree(node)) {
+ case 1:
+ back_propagate_RI(pbqp, node);
+ break;
+ case 2:
+ back_propagate_RII(pbqp, node);
+ break;
+ default:
+ panic("Only nodes with degree one or two should be in this bucket");
+ 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)
+{
+ pbqp_edge *edge = edge_bucket_pop(&edge_bucket);
+
+ simplify_edge(pbqp, edge);
+}
+
+void apply_RI(pbqp *pbqp)
+{
+ 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 {
+ other_node = edge->src;
+ }
+
+ if (pbqp->dump_file) {
+ char txt[100];
+ sprintf(txt, "RI-Reduction of Node n%d", node->index);
+ dump_section(pbqp->dump_file, 2, txt);
+ pbqp_dump_graph(pbqp);
+ fputs("
\nBefore reduction:
\n", pbqp->dump_file);
+ dump_node(pbqp->dump_file, node);
+ dump_node(pbqp->dump_file, other_node);
+ dump_edge(pbqp->dump_file, edge);
+ }
+
+ if (is_src) {
+ pbqp_matrix_add_to_all_cols(mat, node->costs);
+ normalize_towards_target(pbqp, edge);
+ } else {
+ pbqp_matrix_add_to_all_rows(mat, node->costs);
+ normalize_towards_source(pbqp, edge);
+ }
+ disconnect_edge(other_node, edge);
+
+ if (pbqp->dump_file) {
+ fputs("
\nAfter reduction:
\n", pbqp->dump_file);
+ dump_node(pbqp->dump_file, other_node);
+ }
+
+ reorder_node(other_node);
+
+ /* Add node to back propagation list. */
+ node_bucket_insert(&reduced_bucket, node);
+}
+
+void apply_RII(pbqp *pbqp)
+{
+ 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;
+ int tgt_is_src = tgt_edge->src == node;
+ pbqp_matrix *src_mat;
+ pbqp_matrix *tgt_mat;
+ pbqp_node *src_node;
+ pbqp_node *tgt_node;
+ pbqp_matrix *mat;
+ vector *vec;
+ vector *node_vec;
+ vector *src_vec;
+ vector *tgt_vec;
+ unsigned col_index;
+ unsigned col_len;
+ unsigned row_index;
+ unsigned row_len;
+ unsigned node_len;
+
+ assert(pbqp);
+ assert(pbqp_node_get_degree(node) == 2);
+
+ if (src_is_src) {
+ src_node = src_edge->tgt;
+ } else {
+ src_node = src_edge->src;
+ }
+
+ if (tgt_is_src) {
+ tgt_node = tgt_edge->tgt;
+ } else {
+ tgt_node = tgt_edge->src;
+ }
+
+ /* Swap nodes if necessary. */
+ if (tgt_node->index < src_node->index) {
+ pbqp_node *tmp_node;
+ pbqp_edge *tmp_edge;
+
+ tmp_node = src_node;
+ src_node = tgt_node;
+ tgt_node = tmp_node;
+
+ tmp_edge = src_edge;
+ src_edge = tgt_edge;
+ tgt_edge = tmp_edge;
+
+ src_is_src = src_edge->src == node;
+ tgt_is_src = tgt_edge->src == node;
+ }
+
+ if (pbqp->dump_file) {
+ char txt[100];
+ sprintf(txt, "RII-Reduction of Node n%d", node->index);
+ dump_section(pbqp->dump_file, 2, txt);
+ pbqp_dump_graph(pbqp);
+ fputs("
\nBefore reduction:
\n", pbqp->dump_file);
+ 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;
+ tgt_mat = tgt_edge->costs;
+
+ src_vec = src_node->costs;
+ tgt_vec = tgt_node->costs;
+ node_vec = node->costs;
+
+ row_len = src_vec->len;
+ col_len = tgt_vec->len;
+ node_len = node_vec->len;
+
+ mat = pbqp_matrix_alloc(pbqp, row_len, col_len);
+
+ for (row_index = 0; row_index < row_len; ++row_index) {
+ for (col_index = 0; col_index < col_len; ++col_index) {
+ vec = vector_copy(pbqp, node_vec);
+
+ if (src_is_src) {
+ vector_add_matrix_col(vec, src_mat, row_index);
+ } else {
+ vector_add_matrix_row(vec, src_mat, row_index);
+ }
+
+ if (tgt_is_src) {
+ vector_add_matrix_col(vec, tgt_mat, col_index);
+ } else {
+ vector_add_matrix_row(vec, tgt_mat, col_index);
+ }
+
+ mat->entries[row_index * col_len + col_index] = vector_get_min(vec);
+
+ obstack_free(&pbqp->obstack, vec);
+ }
+ }
+
+ pbqp_edge *edge = get_edge(pbqp, src_node->index, tgt_node->index);
+
+ /* Disconnect node. */
+ disconnect_edge(src_node, src_edge);
+ disconnect_edge(tgt_node, tgt_edge);
+
+ /* 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);
+ } else {
+ pbqp_matrix_add(edge->costs, mat);
+
+ /* Free local matrix. */
+ obstack_free(&pbqp->obstack, mat);
+
+ reorder_node(src_node);
+ reorder_node(tgt_node);
+ }
+
+ if (pbqp->dump_file) {
+ fputs("
\nAfter reduction:
\n", pbqp->dump_file);
+ dump_edge(pbqp->dump_file, edge);
+ }
+
+ /* Edge has changed so we simplify it. */
+ simplify_edge(pbqp, edge);
+}
+
+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 = node_bucket_get_length(bucket);
+ unsigned bucket_index;
+ 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;
+ pbqp_matrix *mat;
+ unsigned edge_index;
+ unsigned max_degree = 0;
+ unsigned node_index;
+ unsigned node_len;
+ unsigned min_index = 0;
+ num min = INF_COSTS;
+ int is_src;
+
+ assert(pbqp);
+ assert(node);
+ node_vec = node->costs;
+ node_len = node_vec->len;
+
+ for (node_index = 0; node_index < node_len; ++node_index) {
+ num value = node_vec->entries[node_index].data;
+
+ for (edge_index = 0; edge_index < max_degree; ++edge_index) {
+ edge = node->edges[edge_index];
+ mat = edge->costs;
+ is_src = edge->src == node;
+
+ if (is_src) {
+ vec = vector_copy(pbqp, edge->tgt->costs);
+ vector_add_matrix_row(vec, mat, node_index);
+ } else {
+ vec = vector_copy(pbqp, edge->src->costs);
+ vector_add_matrix_col(vec, mat, node_index);
+ }
+
+ value = pbqp_add(value, vector_get_min(vec));
+
+ obstack_free(&pbqp->obstack, vec);
+ }
+
+ if (value < min) {
+ min = value;
+ min_index = node_index;
+ }
+ }
+
+ 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
\n",
+ node->index, 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) {
+ 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);
+ }
+
+ 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
\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)
+{
+ pbqp_edge *edge;
+ pbqp_node *other;
+ pbqp_matrix *mat;
+ vector *vec;
+ int is_src;
+
+ assert(pbqp);
+ assert(node);
+
+ edge = node->edges[0];
+ mat = edge->costs;
+ is_src = edge->src == node;
+ vec = node->costs;
+
+ if (is_src) {
+ other = edge->tgt;
+ assert(other);
+ vector_add_matrix_col(vec, mat, other->solution);
+ } else {
+ other = edge->src;
+ assert(other);
+ vector_add_matrix_row(vec, mat, other->solution);
+ }
+
+ node->solution = vector_get_min_index(vec);
+ if (pbqp->dump_file) {
+ fprintf(pbqp->dump_file, "node n%d is set to %d
\n", node->index, node->solution);
+ }
+}
+
+void back_propagate_RII(pbqp *pbqp, pbqp_node *node)
+{
+ pbqp_edge *src_edge = node->edges[0];
+ pbqp_edge *tgt_edge = node->edges[1];
+ int src_is_src = src_edge->src == node;
+ int tgt_is_src = tgt_edge->src == node;
+ pbqp_matrix *src_mat;
+ pbqp_matrix *tgt_mat;
+ pbqp_node *src_node;
+ pbqp_node *tgt_node;
+ vector *vec;
+ vector *node_vec;
+ unsigned col_index;
+ unsigned row_index;
+
+ assert(pbqp);
+
+ if (src_is_src) {
+ src_node = src_edge->tgt;
+ } else {
+ src_node = src_edge->src;
+ }
+
+ if (tgt_is_src) {
+ tgt_node = tgt_edge->tgt;
+ } else {
+ tgt_node = tgt_edge->src;
+ }
+
+ /* Swap nodes if necessary. */
+ if (tgt_node->index < src_node->index) {
+ pbqp_node *tmp_node;
+ pbqp_edge *tmp_edge;
+
+ tmp_node = src_node;
+ src_node = tgt_node;
+ tgt_node = tmp_node;
+
+ tmp_edge = src_edge;
+ src_edge = tgt_edge;
+ tgt_edge = tmp_edge;
+
+ src_is_src = src_edge->src == node;
+ tgt_is_src = tgt_edge->src == node;
+ }
+
+ src_mat = src_edge->costs;
+ tgt_mat = tgt_edge->costs;
+
+ node_vec = node->costs;
+
+ row_index = src_node->solution;
+ col_index = tgt_node->solution;
+
+ vec = vector_copy(pbqp, node_vec);
+
+ if (src_is_src) {
+ vector_add_matrix_col(vec, src_mat, row_index);
+ } else {
+ vector_add_matrix_row(vec, src_mat, row_index);
+ }
+
+ if (tgt_is_src) {
+ vector_add_matrix_col(vec, tgt_mat, col_index);
+ } else {
+ vector_add_matrix_row(vec, tgt_mat, col_index);
+ }
+
+ node->solution = vector_get_min_index(vec);
+ if (pbqp->dump_file) {
+ fprintf(pbqp->dump_file, "node n%d is set to %d
\n", node->index, node->solution);
+ }
+
+ obstack_free(&pbqp->obstack, vec);
+}
+
+int node_is_reduced(pbqp_node *node)
+{
+ if (!reduced_bucket) return 0;
+
+ if (pbqp_node_get_degree(node) == 0) return 1;
+
+ return node_bucket_contains(reduced_bucket, node);
+}