+/*
+ * Copyright 2008-2009 Katholieke Universiteit Leuven
+ *
+ * Use of this software is governed by the GNU LGPLv2.1 license
+ *
+ * Written by Sven Verdoolaege, K.U.Leuven, Departement
+ * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
+ */
+
#include "isl_sample.h"
#include "isl_sample_piplib.h"
#include "isl_vec.h"
if (!tab)
return NULL;
- isl_assert(tab->mat->ctx, tab->bset, return NULL);
- bset = tab->bset;
+ bset = isl_tab_peek_bset(tab);
+ isl_assert(tab->mat->ctx, bset, return NULL);
n_eq = tab->n_var - tab->n_col + tab->n_dead;
if (tab->empty || n_eq == 0)
*
* The initial basis is the identity matrix. If the range in some direction
* contains more than one integer value, we perform basis reduction based
- * on the value of ctx->gbr
+ * on the value of ctx->opt->gbr
* - ISL_GBR_NEVER: never perform basis reduction
* - ISL_GBR_ONCE: only perform basis reduction the first
* time such a range is encountered
* - ISL_GBR_ALWAYS: always perform basis reduction when
* such a range is encountered
*
- * When ctx->gbr is set to ISL_GBR_ALWAYS, then we allow the basis
+ * When ctx->opt->gbr is set to ISL_GBR_ALWAYS, then we allow the basis
* reduction computation to return early. That is, as soon as it
* finds a reasonable first direction.
*/
ctx = tab->mat->ctx;
dim = tab->n_var;
- gbr = ctx->gbr;
+ gbr = ctx->opt->gbr;
if (tab->n_unbounded == tab->n_var) {
sample = isl_tab_get_sample_value(tab);
goto error;
if (!empty && isl_tab_sample_is_integer(tab))
break;
- if (!empty && !reduced && ctx->gbr != ISL_GBR_NEVER &&
+ if (!empty && !reduced &&
+ ctx->opt->gbr != ISL_GBR_NEVER &&
isl_int_lt(min->el[level], max->el[level])) {
unsigned gbr_only_first;
- if (ctx->gbr == ISL_GBR_ONCE)
- ctx->gbr = ISL_GBR_NEVER;
+ if (ctx->opt->gbr == ISL_GBR_ONCE)
+ ctx->opt->gbr = ISL_GBR_NEVER;
tab->n_zero = level;
- gbr_only_first = ctx->gbr_only_first;
- ctx->gbr_only_first =
- ctx->gbr == ISL_GBR_ALWAYS;
+ gbr_only_first = ctx->opt->gbr_only_first;
+ ctx->opt->gbr_only_first =
+ ctx->opt->gbr == ISL_GBR_ALWAYS;
tab = isl_tab_compute_reduced_basis(tab);
- ctx->gbr_only_first = gbr_only_first;
+ ctx->opt->gbr_only_first = gbr_only_first;
if (!tab || !tab->basis)
goto error;
reduced = 1;
level--;
init = 0;
if (level >= 0)
- isl_tab_rollback(tab, snap[level]);
+ if (isl_tab_rollback(tab, snap[level]) < 0)
+ goto error;
continue;
}
isl_int_neg(tab->basis->row[1 + level][0], min->el[level]);
} else
sample = isl_vec_alloc(ctx, 0);
- ctx->gbr = gbr;
+ ctx->opt->gbr = gbr;
isl_vec_free(min);
isl_vec_free(max);
free(snap);
return sample;
error:
- ctx->gbr = gbr;
+ ctx->opt->gbr = gbr;
isl_vec_free(min);
isl_vec_free(max);
free(snap);
ctx = bset->ctx;
tab = isl_tab_from_basic_set(bset);
+ if (tab && tab->empty) {
+ isl_tab_free(tab);
+ ISL_F_SET(bset, ISL_BASIC_SET_EMPTY);
+ sample = isl_vec_alloc(bset->ctx, 0);
+ isl_basic_set_free(bset);
+ return sample;
+ }
+
+ if (isl_tab_track_bset(tab, isl_basic_set_copy(bset)) < 0)
+ goto error;
if (!ISL_F_ISSET(bset, ISL_BASIC_SET_NO_IMPLICIT))
tab = isl_tab_detect_implicit_equalities(tab);
if (!tab)
goto error;
- tab->bset = isl_basic_set_copy(bset);
-
sample = isl_tab_sample(tab);
if (!sample)
goto error;
return NULL;
}
+static void vec_sum_of_neg(struct isl_vec *v, isl_int *s)
+{
+ int i;
+
+ isl_int_set_si(*s, 0);
+
+ for (i = 0; i < v->size; ++i)
+ if (isl_int_is_neg(v->el[i]))
+ isl_int_add(*s, *s, v->el[i]);
+}
+
+/* Given a tableau "tab", a tableau "tab_cone" that corresponds
+ * to the recession cone and the inverse of a new basis U = inv(B),
+ * with the unbounded directions in B last,
+ * add constraints to "tab" that ensure any rational value
+ * in the unbounded directions can be rounded up to an integer value.
+ *
+ * The new basis is given by x' = B x, i.e., x = U x'.
+ * For any rational value of the last tab->n_unbounded coordinates
+ * in the update tableau, the value that is obtained by rounding
+ * up this value should be contained in the original tableau.
+ * For any constraint "a x + c >= 0", we therefore need to add
+ * a constraint "a x + c + s >= 0", with s the sum of all negative
+ * entries in the last elements of "a U".
+ *
+ * Since we are not interested in the first entries of any of the "a U",
+ * we first drop the columns of U that correpond to bounded directions.
+ */
+static int tab_shift_cone(struct isl_tab *tab,
+ struct isl_tab *tab_cone, struct isl_mat *U)
+{
+ int i;
+ isl_int v;
+ struct isl_basic_set *bset = NULL;
+
+ if (tab && tab->n_unbounded == 0) {
+ isl_mat_free(U);
+ return 0;
+ }
+ isl_int_init(v);
+ if (!tab || !tab_cone || !U)
+ goto error;
+ bset = isl_tab_peek_bset(tab_cone);
+ U = isl_mat_drop_cols(U, 0, tab->n_var - tab->n_unbounded);
+ for (i = 0; i < bset->n_ineq; ++i) {
+ int ok;
+ struct isl_vec *row = NULL;
+ if (isl_tab_is_equality(tab_cone, tab_cone->n_eq + i))
+ continue;
+ row = isl_vec_alloc(bset->ctx, tab_cone->n_var);
+ if (!row)
+ goto error;
+ isl_seq_cpy(row->el, bset->ineq[i] + 1, tab_cone->n_var);
+ row = isl_vec_mat_product(row, isl_mat_copy(U));
+ if (!row)
+ goto error;
+ vec_sum_of_neg(row, &v);
+ isl_vec_free(row);
+ if (isl_int_is_zero(v))
+ continue;
+ tab = isl_tab_extend(tab, 1);
+ isl_int_add(bset->ineq[i][0], bset->ineq[i][0], v);
+ ok = isl_tab_add_ineq(tab, bset->ineq[i]) >= 0;
+ isl_int_sub(bset->ineq[i][0], bset->ineq[i][0], v);
+ if (!ok)
+ goto error;
+ }
+
+ isl_mat_free(U);
+ isl_int_clear(v);
+ return 0;
+error:
+ isl_mat_free(U);
+ isl_int_clear(v);
+ return -1;
+}
+
+/* Compute and return an initial basis for the possibly
+ * unbounded tableau "tab". "tab_cone" is a tableau
+ * for the corresponding recession cone.
+ * Additionally, add constraints to "tab" that ensure
+ * that any rational value for the unbounded directions
+ * can be rounded up to an integer value.
+ *
+ * If the tableau is bounded, i.e., if the recession cone
+ * is zero-dimensional, then we just use inital_basis.
+ * Otherwise, we construct a basis whose first directions
+ * correspond to equalities, followed by bounded directions,
+ * i.e., equalities in the recession cone.
+ * The remaining directions are then unbounded.
+ */
+int isl_tab_set_initial_basis_with_cone(struct isl_tab *tab,
+ struct isl_tab *tab_cone)
+{
+ struct isl_mat *eq;
+ struct isl_mat *cone_eq;
+ struct isl_mat *U, *Q;
+
+ if (!tab || !tab_cone)
+ return -1;
+
+ if (tab_cone->n_col == tab_cone->n_dead) {
+ tab->basis = initial_basis(tab);
+ return tab->basis ? 0 : -1;
+ }
+
+ eq = tab_equalities(tab);
+ if (!eq)
+ return -1;
+ tab->n_zero = eq->n_row;
+ cone_eq = tab_equalities(tab_cone);
+ eq = isl_mat_concat(eq, cone_eq);
+ if (!eq)
+ return -1;
+ tab->n_unbounded = tab->n_var - (eq->n_row - tab->n_zero);
+ eq = isl_mat_left_hermite(eq, 0, &U, &Q);
+ if (!eq)
+ return -1;
+ isl_mat_free(eq);
+ tab->basis = isl_mat_lin_to_aff(Q);
+ if (tab_shift_cone(tab, tab_cone, U) < 0)
+ return -1;
+ if (!tab->basis)
+ return -1;
+ return 0;
+}
+
/* Compute and return a sample point in bset using generalized basis
* reduction. We first check if the input set has a non-trivial
* recession cone. If so, we perform some extra preprocessing in
if (dim == 1)
return interval_sample(bset);
- switch (bset->ctx->ilp_solver) {
+ switch (bset->ctx->opt->ilp_solver) {
case ISL_ILP_PIP:
return pip_sample(bset);
case ISL_ILP_GBR:
isl_int_neg(bset->eq[k][0], vec->el[1 + i]);
isl_int_set(bset->eq[k][1 + i], vec->el[0]);
}
- isl_vec_free(vec);
+ bset->sample = vec;
return bset;
error:
projects / platform / upstream / isl.git / blobdiff