isl_scan.c

   1 /*
   2  * Copyright 2008-2009 Katholieke Universiteit Leuven
   3  *
   4  * Use of this software is governed by the MIT license
   5  *
   6  * Written by Sven Verdoolaege, K.U.Leuven, Departement
   7  * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
   8  */
   9
  10 #include <isl_ctx_private.h>
  11 #include <isl_map_private.h>
  12 #include "isl_basis_reduction.h"
  13 #include "isl_scan.h"
  14 #include <isl_seq.h>
  15 #include "isl_tab.h"
  16 #include <isl_val_private.h>
  17
  18 struct isl_counter {
  19         struct isl_scan_callback callback;
  20         isl_int count;
  21         isl_int max;
  22 };
  23
  24 static int increment_counter(struct isl_scan_callback *cb,
  25         __isl_take isl_vec *sample)
  26 {
  27         struct isl_counter *cnt = (struct isl_counter *)cb;
  28
  29         isl_int_add_ui(cnt->count, cnt->count, 1);
  30
  31         isl_vec_free(sample);
  32
  33         if (isl_int_is_zero(cnt->max) || isl_int_lt(cnt->count, cnt->max))
  34                 return 0;
  35         return -1;
  36 }
  37
  38 static int increment_range(struct isl_scan_callback *cb, isl_int min, isl_int max)
  39 {
  40         struct isl_counter *cnt = (struct isl_counter *)cb;
  41
  42         isl_int_add(cnt->count, cnt->count, max);
  43         isl_int_sub(cnt->count, cnt->count, min);
  44         isl_int_add_ui(cnt->count, cnt->count, 1);
  45
  46         if (isl_int_is_zero(cnt->max) || isl_int_lt(cnt->count, cnt->max))
  47                 return 0;
  48         isl_int_set(cnt->count, cnt->max);
  49         return -1;
  50 }
  51
  52 /* Call callback->add with the current sample value of the tableau "tab".
  53  */
  54 static int add_solution(struct isl_tab *tab, struct isl_scan_callback *callback)
  55 {
  56         struct isl_vec *sample;
  57
  58         if (!tab)
  59                 return -1;
  60         sample = isl_tab_get_sample_value(tab);
  61         if (!sample)
  62                 return -1;
  63
  64         return callback->add(callback, sample);
  65 }
  66
  67 static int scan_0D(struct isl_basic_set *bset,
  68         struct isl_scan_callback *callback)
  69 {
  70         struct isl_vec *sample;
  71
  72         sample = isl_vec_alloc(bset->ctx, 1);
  73         isl_basic_set_free(bset);
  74
  75         if (!sample)
  76                 return -1;
  77
  78         isl_int_set_si(sample->el[0], 1);
  79
  80         return callback->add(callback, sample);
  81 }
  82
  83 /* Look for all integer points in "bset", which is assumed to be bounded,
  84  * and call callback->add on each of them.
  85  *
  86  * We first compute a reduced basis for the set and then scan
  87  * the set in the directions of this basis.
  88  * We basically perform a depth first search, where in each level i
  89  * we compute the range in the i-th basis vector direction, given
  90  * fixed values in the directions of the previous basis vector.
  91  * We then add an equality to the tableau fixing the value in the
  92  * direction of the current basis vector to each value in the range
  93  * in turn and then continue to the next level.
  94  *
  95  * The search is implemented iteratively.  "level" identifies the current
  96  * basis vector.  "init" is true if we want the first value at the current
  97  * level and false if we want the next value.
  98  * Solutions are added in the leaves of the search tree, i.e., after
  99  * we have fixed a value in each direction of the basis.
 100  */
 101 int isl_basic_set_scan(struct isl_basic_set *bset,
 102         struct isl_scan_callback *callback)
 103 {
 104         unsigned dim;
 105         struct isl_mat *B = NULL;
 106         struct isl_tab *tab = NULL;
 107         struct isl_vec *min;
 108         struct isl_vec *max;
 109         struct isl_tab_undo **snap;
 110         int level;
 111         int init;
 112         enum isl_lp_result res;
 113
 114         if (!bset)
 115                 return -1;
 116
 117         dim = isl_basic_set_total_dim(bset);
 118         if (dim == 0)
 119                 return scan_0D(bset, callback);
 120
 121         min = isl_vec_alloc(bset->ctx, dim);
 122         max = isl_vec_alloc(bset->ctx, dim);
 123         snap = isl_alloc_array(bset->ctx, struct isl_tab_undo *, dim);
 124
 125         if (!min || !max || !snap)
 126                 goto error;
 127
 128         tab = isl_tab_from_basic_set(bset, 0);
 129         if (!tab)
 130                 goto error;
 131         if (isl_tab_extend_cons(tab, dim + 1) < 0)
 132                 goto error;
 133
 134         tab->basis = isl_mat_identity(bset->ctx, 1 + dim);
 135         if (1)
 136                 tab = isl_tab_compute_reduced_basis(tab);
 137         if (!tab)
 138                 goto error;
 139         B = isl_mat_copy(tab->basis);
 140         if (!B)
 141                 goto error;
 142
 143         level = 0;
 144         init = 1;
 145
 146         while (level >= 0) {
 147                 int empty = 0;
 148                 if (init) {
 149                         res = isl_tab_min(tab, B->row[1 + level],
 150                                     bset->ctx->one, &min->el[level], NULL, 0);
 151                         if (res == isl_lp_empty)
 152                                 empty = 1;
 153                         if (res == isl_lp_error || res == isl_lp_unbounded)
 154                                 goto error;
 155                         isl_seq_neg(B->row[1 + level] + 1,
 156                                     B->row[1 + level] + 1, dim);
 157                         res = isl_tab_min(tab, B->row[1 + level],
 158                                     bset->ctx->one, &max->el[level], NULL, 0);
 159                         isl_seq_neg(B->row[1 + level] + 1,
 160                                     B->row[1 + level] + 1, dim);
 161                         isl_int_neg(max->el[level], max->el[level]);
 162                         if (res == isl_lp_empty)
 163                                 empty = 1;
 164                         if (res == isl_lp_error || res == isl_lp_unbounded)
 165                                 goto error;
 166                         snap[level] = isl_tab_snap(tab);
 167                 } else
 168                         isl_int_add_ui(min->el[level], min->el[level], 1);
 169
 170                 if (empty || isl_int_gt(min->el[level], max->el[level])) {
 171                         level--;
 172                         init = 0;
 173                         if (level >= 0)
 174                                 if (isl_tab_rollback(tab, snap[level]) < 0)
 175                                         goto error;
 176                         continue;
 177                 }
 178                 if (level == dim - 1 && callback->add == increment_counter) {
 179                         if (increment_range(callback,
 180                                             min->el[level], max->el[level]))
 181                                 goto error;
 182                         level--;
 183                         init = 0;
 184                         if (level >= 0)
 185                                 if (isl_tab_rollback(tab, snap[level]) < 0)
 186                                         goto error;
 187                         continue;
 188                 }
 189                 isl_int_neg(B->row[1 + level][0], min->el[level]);
 190                 if (isl_tab_add_valid_eq(tab, B->row[1 + level]) < 0)
 191                         goto error;
 192                 isl_int_set_si(B->row[1 + level][0], 0);
 193                 if (level < dim - 1) {
 194                         ++level;
 195                         init = 1;
 196                         continue;
 197                 }
 198                 if (add_solution(tab, callback) < 0)
 199                         goto error;
 200                 init = 0;
 201                 if (isl_tab_rollback(tab, snap[level]) < 0)
 202                         goto error;
 203         }
 204
 205         isl_tab_free(tab);
 206         free(snap);
 207         isl_vec_free(min);
 208         isl_vec_free(max);
 209         isl_basic_set_free(bset);
 210         isl_mat_free(B);
 211         return 0;
 212 error:
 213         isl_tab_free(tab);
 214         free(snap);
 215         isl_vec_free(min);
 216         isl_vec_free(max);
 217         isl_basic_set_free(bset);
 218         isl_mat_free(B);
 219         return -1;
 220 }
 221
 222 int isl_set_scan(__isl_take isl_set *set, struct isl_scan_callback *callback)
 223 {
 224         int i;
 225
 226         if (!set || !callback)
 227                 goto error;
 228
 229         set = isl_set_cow(set);
 230         set = isl_set_make_disjoint(set);
 231         set = isl_set_compute_divs(set);
 232         if (!set)
 233                 goto error;
 234
 235         for (i = 0; i < set->n; ++i)
 236                 if (isl_basic_set_scan(isl_basic_set_copy(set->p[i]),
 237                                         callback) < 0)
 238                         goto error;
 239
 240         isl_set_free(set);
 241         return 0;
 242 error:
 243         isl_set_free(set);
 244         return -1;
 245 }
 246
 247 int isl_basic_set_count_upto(__isl_keep isl_basic_set *bset,
 248         isl_int max, isl_int *count)
 249 {
 250         struct isl_counter cnt = { { &increment_counter } };
 251
 252         if (!bset)
 253                 return -1;
 254
 255         isl_int_init(cnt.count);
 256         isl_int_init(cnt.max);
 257
 258         isl_int_set_si(cnt.count, 0);
 259         isl_int_set(cnt.max, max);
 260         if (isl_basic_set_scan(isl_basic_set_copy(bset), &cnt.callback) < 0 &&
 261             isl_int_lt(cnt.count, cnt.max))
 262                 goto error;
 263
 264         isl_int_set(*count, cnt.count);
 265         isl_int_clear(cnt.max);
 266         isl_int_clear(cnt.count);
 267
 268         return 0;
 269 error:
 270         isl_int_clear(cnt.count);
 271         return -1;
 272 }
 273
 274 int isl_set_count_upto(__isl_keep isl_set *set, isl_int max, isl_int *count)
 275 {
 276         struct isl_counter cnt = { { &increment_counter } };
 277
 278         if (!set)
 279                 return -1;
 280
 281         isl_int_init(cnt.count);
 282         isl_int_init(cnt.max);
 283
 284         isl_int_set_si(cnt.count, 0);
 285         isl_int_set(cnt.max, max);
 286         if (isl_set_scan(isl_set_copy(set), &cnt.callback) < 0 &&
 287             isl_int_lt(cnt.count, cnt.max))
 288                 goto error;
 289
 290         isl_int_set(*count, cnt.count);
 291         isl_int_clear(cnt.max);
 292         isl_int_clear(cnt.count);
 293
 294         return 0;
 295 error:
 296         isl_int_clear(cnt.count);
 297         return -1;
 298 }
 299
 300 int isl_set_count(__isl_keep isl_set *set, isl_int *count)
 301 {
 302         if (!set)
 303                 return -1;
 304         return isl_set_count_upto(set, set->ctx->zero, count);
 305 }
 306
 307 /* Count the total number of elements in "set" (in an inefficient way) and
 308  * return the result.
 309  */
 310 __isl_give isl_val *isl_set_count_val(__isl_keep isl_set *set)
 311 {
 312         isl_val *v;
 313
 314         if (!set)
 315                 return NULL;
 316         v = isl_val_zero(isl_set_get_ctx(set));
 317         v = isl_val_cow(v);
 318         if (!v)
 319                 return NULL;
 320         if (isl_set_count(set, &v->n) < 0)
 321                 v = isl_val_free(v);
 322         return v;
 323 }