basis_reduction_tab.c

   1 #include <assert.h>
   2 #include "isl_tab.h"
   3
   4 struct tab_lp {
   5         struct isl_ctx  *ctx;
   6         struct isl_vec  *row;
   7         struct isl_tab  *tab;
   8         struct isl_tab_undo     **stack;
   9         isl_int         *obj;
  10         isl_int          opt;
  11         isl_int          opt_denom;
  12         int              neq;
  13         unsigned         dim;
  14         int              n_ineq;
  15 };
  16
  17 static struct tab_lp *init_lp(struct isl_basic_set *bset);
  18 static void set_lp_obj(struct tab_lp *lp, isl_int *row, int dim);
  19 static int solve_lp(struct tab_lp *lp);
  20 static void get_obj_val(struct tab_lp* lp, mpq_t *F);
  21 static void delete_lp(struct tab_lp *lp);
  22 static int add_lp_row(struct tab_lp *lp, isl_int *row, int dim);
  23 static void get_alpha(struct tab_lp* lp, int row, mpq_t *alpha);
  24 static void del_lp_row(struct tab_lp *lp);
  25
  26 #define GBR_LP                              struct tab_lp
  27 #define GBR_type                            mpq_t
  28 #define GBR_init(v)                         mpq_init(v)
  29 #define GBR_clear(v)                        mpq_clear(v)
  30 #define GBR_set(a,b)                        mpq_set(a,b)
  31 #define GBR_set_ui(a,b)                     mpq_set_ui(a,b,1)
  32 #define GBR_mul(a,b,c)                      mpq_mul(a,b,c)
  33 #define GBR_lt(a,b)                         (mpq_cmp(a,b) < 0)
  34 #define GBR_floor(a,b)                      mpz_fdiv_q(a,mpq_numref(b),mpq_denref(b))
  35 #define GBR_ceil(a,b)                       mpz_cdiv_q(a,mpq_numref(b),mpq_denref(b))
  36 #define GBR_lp_init(P)                      init_lp(P)
  37 #define GBR_lp_set_obj(lp, obj, dim)        set_lp_obj(lp, obj, dim)
  38 #define GBR_lp_solve(lp)                    solve_lp(lp)
  39 #define GBR_lp_get_obj_val(lp, F)           get_obj_val(lp, F)
  40 #define GBR_lp_delete(lp)                   delete_lp(lp)
  41 #define GBR_lp_next_row(lp)                 lp->neq
  42 #define GBR_lp_add_row(lp, row, dim)        add_lp_row(lp, row, dim)
  43 #define GBR_lp_get_alpha(lp, row, alpha)    get_alpha(lp, row, alpha)
  44 #define GBR_lp_del_row(lp)                  del_lp_row(lp);
  45 #include "basis_reduction_templ.c"
  46
  47 /* Set up a tableau for the Cartesian product of bset with itself.
  48  * This could be optimized by first setting up a tableau for bset
  49  * and then performing the Cartesian product on the tableau.
  50  */
  51 static struct isl_tab *gbr_tab(struct isl_basic_set *bset,
  52         struct isl_vec *row)
  53 {
  54         int i, j;
  55         unsigned dim;
  56         struct isl_tab *tab;
  57
  58         if (!bset || !row)
  59                 return NULL;
  60
  61         dim = isl_basic_set_total_dim(bset);
  62         tab = isl_tab_alloc(bset->ctx, 2 * bset->n_ineq + dim + 1, 2 * dim, 0);
  63
  64         for (i = 0; i < 2; ++i) {
  65                 isl_seq_clr(row->el + 1 + (1 - i) * dim, dim);
  66                 for (j = 0; j < bset->n_ineq; ++j) {
  67                         isl_int_set(row->el[0], bset->ineq[j][0]);
  68                         isl_seq_cpy(row->el + 1 + i * dim,
  69                                     bset->ineq[j] + 1, dim);
  70                         tab = isl_tab_add_ineq(tab, row->el);
  71                         if (!tab || tab->empty)
  72                                 return tab;
  73                 }
  74         }
  75
  76         return tab;
  77 }
  78
  79 static struct tab_lp *init_lp(struct isl_basic_set *bset)
  80 {
  81         struct tab_lp *lp = NULL;
  82
  83         if (!bset)
  84                 return NULL;
  85
  86         isl_assert(bset->ctx, bset->n_eq == 0, return NULL);
  87
  88         lp = isl_calloc_type(bset->ctx, struct tab_lp);
  89         if (!lp)
  90                 return NULL;
  91
  92         isl_int_init(lp->opt);
  93         isl_int_init(lp->opt_denom);
  94
  95         lp->dim = isl_basic_set_total_dim(bset);
  96         lp->n_ineq = bset->n_ineq;
  97
  98         lp->ctx = bset->ctx;
  99         isl_ctx_ref(lp->ctx);
 100
 101         lp->stack = isl_alloc_array(lp->ctx, struct isl_tab_undo *, lp->dim);
 102
 103         lp->row = isl_vec_alloc(lp->ctx, 1 + 2 * lp->dim);
 104         if (!lp->row)
 105                 goto error;
 106         lp->tab = gbr_tab(bset, lp->row);
 107         if (!lp->tab)
 108                 goto error;
 109         lp->obj = NULL;
 110         lp->neq = 0;
 111
 112         return lp;
 113 error:
 114         delete_lp(lp);
 115         return NULL;
 116 }
 117
 118 static void set_lp_obj(struct tab_lp *lp, isl_int *row, int dim)
 119 {
 120         lp->obj = row;
 121 }
 122
 123 static int solve_lp(struct tab_lp *lp)
 124 {
 125         enum isl_lp_result res;
 126         unsigned flags = 0;
 127
 128         isl_int_set_si(lp->row->el[0], 0);
 129         isl_seq_cpy(lp->row->el + 1, lp->obj, lp->dim);
 130         isl_seq_neg(lp->row->el + 1 + lp->dim, lp->obj, lp->dim);
 131         if (lp->neq)
 132                 flags = ISL_TAB_SAVE_DUAL;
 133         res = isl_tab_min(lp->tab, lp->row->el, lp->ctx->one,
 134                           &lp->opt, &lp->opt_denom, flags);
 135         if (res != isl_lp_ok)
 136                 return -1;
 137         return 0;
 138 }
 139
 140 static void get_obj_val(struct tab_lp* lp, mpq_t *F)
 141 {
 142         isl_int_neg(mpq_numref(*F), lp->opt);
 143         isl_int_set(mpq_denref(*F), lp->opt_denom);
 144 }
 145
 146 static void delete_lp(struct tab_lp *lp)
 147 {
 148         if (!lp)
 149                 return;
 150
 151         isl_int_clear(lp->opt);
 152         isl_int_clear(lp->opt_denom);
 153         isl_vec_free(lp->row);
 154         free(lp->stack);
 155         isl_tab_free(lp->tab);
 156         isl_ctx_deref(lp->ctx);
 157         free(lp);
 158 }
 159
 160 static int add_lp_row(struct tab_lp *lp, isl_int *row, int dim)
 161 {
 162         lp->stack[lp->neq] = isl_tab_snap(lp->tab);
 163
 164         isl_int_set_si(lp->row->el[0], 0);
 165         isl_seq_cpy(lp->row->el + 1, row, lp->dim);
 166         isl_seq_neg(lp->row->el + 1 + lp->dim, row, lp->dim);
 167
 168         lp->tab = isl_tab_add_valid_eq(lp->tab, lp->row->el);
 169
 170         return lp->neq++;
 171 }
 172
 173 static void get_alpha(struct tab_lp* lp, int row, mpq_t *alpha)
 174 {
 175         row += 2 * lp->n_ineq;
 176         isl_int_neg(mpq_numref(*alpha), lp->tab->dual->el[1 + row]);
 177         isl_int_set(mpq_denref(*alpha), lp->tab->dual->el[0]);
 178 }
 179
 180 static void del_lp_row(struct tab_lp *lp)
 181 {
 182         lp->neq--;
 183         isl_tab_rollback(lp->tab, lp->stack[lp->neq]);
 184 }