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 #include <isl_vec_private.h>
  18
  19 struct isl_counter {
  20         struct isl_scan_callback callback;
  21         isl_int count;
  22         isl_int max;
  23 };
  24
  25 static isl_stat increment_counter(struct isl_scan_callback *cb,
  26         __isl_take isl_vec *sample)
  27 {
  28         struct isl_counter *cnt = (struct isl_counter *)cb;
  29
  30         isl_int_add_ui(cnt->count, cnt->count, 1);
  31
  32         isl_vec_free(sample);
  33
  34         if (isl_int_is_zero(cnt->max) || isl_int_lt(cnt->count, cnt->max))
  35                 return isl_stat_ok;
  36         return isl_stat_error;
  37 }
  38
  39 static int increment_range(struct isl_scan_callback *cb, isl_int min, isl_int max)
  40 {
  41         struct isl_counter *cnt = (struct isl_counter *)cb;
  42
  43         isl_int_add(cnt->count, cnt->count, max);
  44         isl_int_sub(cnt->count, cnt->count, min);
  45         isl_int_add_ui(cnt->count, cnt->count, 1);
  46
  47         if (isl_int_is_zero(cnt->max) || isl_int_lt(cnt->count, cnt->max))
  48                 return 0;
  49         isl_int_set(cnt->count, cnt->max);
  50         return -1;
  51 }
  52
  53 /* Call callback->add with the current sample value of the tableau "tab".
  54  */
  55 static int add_solution(struct isl_tab *tab, struct isl_scan_callback *callback)
  56 {
  57         struct isl_vec *sample;
  58
  59         if (!tab)
  60                 return -1;
  61         sample = isl_tab_get_sample_value(tab);
  62         if (!sample)
  63                 return -1;
  64
  65         return callback->add(callback, sample);
  66 }
  67
  68 static int scan_0D(struct isl_basic_set *bset,
  69         struct isl_scan_callback *callback)
  70 {
  71         struct isl_vec *sample;
  72
  73         sample = isl_vec_alloc(bset->ctx, 1);
  74         isl_basic_set_free(bset);
  75
  76         if (!sample)
  77                 return -1;
  78
  79         isl_int_set_si(sample->el[0], 1);
  80
  81         return callback->add(callback, sample);
  82 }
  83
  84 /* Look for all integer points in "bset", which is assumed to be bounded,
  85  * and call callback->add on each of them.
  86  *
  87  * We first compute a reduced basis for the set and then scan
  88  * the set in the directions of this basis.
  89  * We basically perform a depth first search, where in each level i
  90  * we compute the range in the i-th basis vector direction, given
  91  * fixed values in the directions of the previous basis vector.
  92  * We then add an equality to the tableau fixing the value in the
  93  * direction of the current basis vector to each value in the range
  94  * in turn and then continue to the next level.
  95  *
  96  * The search is implemented iteratively.  "level" identifies the current
  97  * basis vector.  "init" is true if we want the first value at the current
  98  * level and false if we want the next value.
  99  * Solutions are added in the leaves of the search tree, i.e., after
 100  * we have fixed a value in each direction of the basis.
 101  */
 102 int isl_basic_set_scan(struct isl_basic_set *bset,
 103         struct isl_scan_callback *callback)
 104 {
 105         unsigned dim;
 106         struct isl_mat *B = NULL;
 107         struct isl_tab *tab = NULL;
 108         struct isl_vec *min;
 109         struct isl_vec *max;
 110         struct isl_tab_undo **snap;
 111         int level;
 112         int init;
 113         enum isl_lp_result res;
 114
 115         if (!bset)
 116                 return -1;
 117
 118         dim = isl_basic_set_total_dim(bset);
 119         if (dim == 0)
 120                 return scan_0D(bset, callback);
 121
 122         min = isl_vec_alloc(bset->ctx, dim);
 123         max = isl_vec_alloc(bset->ctx, dim);
 124         snap = isl_alloc_array(bset->ctx, struct isl_tab_undo *, dim);
 125
 126         if (!min || !max || !snap)
 127                 goto error;
 128
 129         tab = isl_tab_from_basic_set(bset, 0);
 130         if (!tab)
 131                 goto error;
 132         if (isl_tab_extend_cons(tab, dim + 1) < 0)
 133                 goto error;
 134
 135         tab->basis = isl_mat_identity(bset->ctx, 1 + dim);
 136         if (1)
 137                 tab = isl_tab_compute_reduced_basis(tab);
 138         if (!tab)
 139                 goto error;
 140         B = isl_mat_copy(tab->basis);
 141         if (!B)
 142                 goto error;
 143
 144         level = 0;
 145         init = 1;
 146
 147         while (level >= 0) {
 148                 int empty = 0;
 149                 if (init) {
 150                         res = isl_tab_min(tab, B->row[1 + level],
 151                                     bset->ctx->one, &min->el[level], NULL, 0);
 152                         if (res == isl_lp_empty)
 153                                 empty = 1;
 154                         if (res == isl_lp_error || res == isl_lp_unbounded)
 155                                 goto error;
 156                         isl_seq_neg(B->row[1 + level] + 1,
 157                                     B->row[1 + level] + 1, dim);
 158                         res = isl_tab_min(tab, B->row[1 + level],
 159                                     bset->ctx->one, &max->el[level], NULL, 0);
 160                         isl_seq_neg(B->row[1 + level] + 1,
 161                                     B->row[1 + level] + 1, dim);
 162                         isl_int_neg(max->el[level], max->el[level]);
 163                         if (res == isl_lp_empty)
 164                                 empty = 1;
 165                         if (res == isl_lp_error || res == isl_lp_unbounded)
 166                                 goto error;
 167                         snap[level] = isl_tab_snap(tab);
 168                 } else
 169                         isl_int_add_ui(min->el[level], min->el[level], 1);
 170
 171                 if (empty || isl_int_gt(min->el[level], max->el[level])) {
 172                         level--;
 173                         init = 0;
 174                         if (level >= 0)
 175                                 if (isl_tab_rollback(tab, snap[level]) < 0)
 176                                         goto error;
 177                         continue;
 178                 }
 179                 if (level == dim - 1 && callback->add == increment_counter) {
 180                         if (increment_range(callback,
 181                                             min->el[level], max->el[level]))
 182                                 goto error;
 183                         level--;
 184                         init = 0;
 185                         if (level >= 0)
 186                                 if (isl_tab_rollback(tab, snap[level]) < 0)
 187                                         goto error;
 188                         continue;
 189                 }
 190                 isl_int_neg(B->row[1 + level][0], min->el[level]);
 191                 if (isl_tab_add_valid_eq(tab, B->row[1 + level]) < 0)
 192                         goto error;
 193                 isl_int_set_si(B->row[1 + level][0], 0);
 194                 if (level < dim - 1) {
 195                         ++level;
 196                         init = 1;
 197                         continue;
 198                 }
 199                 if (add_solution(tab, callback) < 0)
 200                         goto error;
 201                 init = 0;
 202                 if (isl_tab_rollback(tab, snap[level]) < 0)
 203                         goto error;
 204         }
 205
 206         isl_tab_free(tab);
 207         free(snap);
 208         isl_vec_free(min);
 209         isl_vec_free(max);
 210         isl_basic_set_free(bset);
 211         isl_mat_free(B);
 212         return 0;
 213 error:
 214         isl_tab_free(tab);
 215         free(snap);
 216         isl_vec_free(min);
 217         isl_vec_free(max);
 218         isl_basic_set_free(bset);
 219         isl_mat_free(B);
 220         return -1;
 221 }
 222
 223 int isl_set_scan(__isl_take isl_set *set, struct isl_scan_callback *callback)
 224 {
 225         int i;
 226
 227         if (!set || !callback)
 228                 goto error;
 229
 230         set = isl_set_cow(set);
 231         set = isl_set_make_disjoint(set);
 232         set = isl_set_compute_divs(set);
 233         if (!set)
 234                 goto error;
 235
 236         for (i = 0; i < set->n; ++i)
 237                 if (isl_basic_set_scan(isl_basic_set_copy(set->p[i]),
 238                                         callback) < 0)
 239                         goto error;
 240
 241         isl_set_free(set);
 242         return 0;
 243 error:
 244         isl_set_free(set);
 245         return -1;
 246 }
 247
 248 int isl_basic_set_count_upto(__isl_keep isl_basic_set *bset,
 249         isl_int max, isl_int *count)
 250 {
 251         struct isl_counter cnt = { { &increment_counter } };
 252
 253         if (!bset)
 254                 return -1;
 255
 256         isl_int_init(cnt.count);
 257         isl_int_init(cnt.max);
 258
 259         isl_int_set_si(cnt.count, 0);
 260         isl_int_set(cnt.max, max);
 261         if (isl_basic_set_scan(isl_basic_set_copy(bset), &cnt.callback) < 0 &&
 262             isl_int_lt(cnt.count, cnt.max))
 263                 goto error;
 264
 265         isl_int_set(*count, cnt.count);
 266         isl_int_clear(cnt.max);
 267         isl_int_clear(cnt.count);
 268
 269         return 0;
 270 error:
 271         isl_int_clear(cnt.count);
 272         return -1;
 273 }
 274
 275 int isl_set_count_upto(__isl_keep isl_set *set, isl_int max, isl_int *count)
 276 {
 277         struct isl_counter cnt = { { &increment_counter } };
 278
 279         if (!set)
 280                 return -1;
 281
 282         isl_int_init(cnt.count);
 283         isl_int_init(cnt.max);
 284
 285         isl_int_set_si(cnt.count, 0);
 286         isl_int_set(cnt.max, max);
 287         if (isl_set_scan(isl_set_copy(set), &cnt.callback) < 0 &&
 288             isl_int_lt(cnt.count, cnt.max))
 289                 goto error;
 290
 291         isl_int_set(*count, cnt.count);
 292         isl_int_clear(cnt.max);
 293         isl_int_clear(cnt.count);
 294
 295         return 0;
 296 error:
 297         isl_int_clear(cnt.count);
 298         return -1;
 299 }
 300
 301 int isl_set_count(__isl_keep isl_set *set, isl_int *count)
 302 {
 303         if (!set)
 304                 return -1;
 305         return isl_set_count_upto(set, set->ctx->zero, count);
 306 }
 307
 308 /* Count the total number of elements in "set" (in an inefficient way) and
 309  * return the result.
 310  */
 311 __isl_give isl_val *isl_set_count_val(__isl_keep isl_set *set)
 312 {
 313         isl_val *v;
 314
 315         if (!set)
 316                 return NULL;
 317         v = isl_val_zero(isl_set_get_ctx(set));
 318         v = isl_val_cow(v);
 319         if (!v)
 320                 return NULL;
 321         if (isl_set_count(set, &v->n) < 0)
 322                 v = isl_val_free(v);
 323         return v;
 324 }