+ if (!bset)
+ goto error;
+ bset = isl_basic_set_extend_constraints(bset, 0, 1);
+ k = isl_basic_set_alloc_inequality(bset);
+ if (k < 0)
+ goto error;
+ isl_seq_clr(bset->ineq[k] + 1, isl_basic_set_total_dim(bset));
+ isl_int_set_si(bset->ineq[k][0], 1);
+ bset = isl_basic_set_preimage(bset, T);
+ return bset;
+error:
+ isl_mat_free(T);
+ isl_basic_set_free(bset);
+ return NULL;
+}
+
+/* Compute the convex hull of a pair of basic sets without any parameters or
+ * integer divisions, where the convex hull is known to be pointed,
+ * but the basic sets may be unbounded.
+ *
+ * We turn this problem into the computation of a convex hull of a pair
+ * _bounded_ polyhedra by "changing the direction of the homogeneous
+ * dimension". This idea is due to Matthias Koeppe.
+ *
+ * Consider the cones in homogeneous space that correspond to the
+ * input polyhedra. The rays of these cones are also rays of the
+ * polyhedra if the coordinate that corresponds to the homogeneous
+ * dimension is zero. That is, if the inner product of the rays
+ * with the homogeneous direction is zero.
+ * The cones in the homogeneous space can also be considered to
+ * correspond to other pairs of polyhedra by chosing a different
+ * homogeneous direction. To ensure that both of these polyhedra
+ * are bounded, we need to make sure that all rays of the cones
+ * correspond to vertices and not to rays.
+ * Let s be a direction such that <s, r> > 0 for all rays r of both cones.
+ * Then using s as a homogeneous direction, we obtain a pair of polytopes.
+ * The vector s is computed in valid_direction.
+ *
+ * Note that we need to consider _all_ rays of the cones and not just
+ * the rays that correspond to rays in the polyhedra. If we were to
+ * only consider those rays and turn them into vertices, then we
+ * may inadvertently turn some vertices into rays.
+ *
+ * The standard homogeneous direction is the unit vector in the 0th coordinate.
+ * We therefore transform the two polyhedra such that the selected
+ * direction is mapped onto this standard direction and then proceed
+ * with the normal computation.
+ * Let S be a non-singular square matrix with s as its first row,
+ * then we want to map the polyhedra to the space
+ *
+ * [ y' ] [ y ] [ y ] [ y' ]
+ * [ x' ] = S [ x ] i.e., [ x ] = S^{-1} [ x' ]
+ *
+ * We take S to be the unimodular completion of s to limit the growth
+ * of the coefficients in the following computations.
+ *
+ * Let b_i + A_i x >= 0 be the constraints of polyhedron i.
+ * We first move to the homogeneous dimension
+ *
+ * b_i y + A_i x >= 0 [ b_i A_i ] [ y ] [ 0 ]
+ * y >= 0 or [ 1 0 ] [ x ] >= [ 0 ]
+ *
+ * Then we change directoin
+ *
+ * [ b_i A_i ] [ y' ] [ y' ]
+ * [ 1 0 ] S^{-1} [ x' ] >= 0 or [ b_i' A_i' ] [ x' ] >= 0
+ *
+ * Then we compute the convex hull of the polytopes b_i' + A_i' x' >= 0
+ * resulting in b' + A' x' >= 0, which we then convert back
+ *
+ * [ y ] [ y ]
+ * [ b' A' ] S [ x ] >= 0 or [ b A ] [ x ] >= 0
+ *
+ * The polyhedron b + A x >= 0 is then the convex hull of the input polyhedra.
+ */
+static struct isl_basic_set *convex_hull_pair_pointed(
+ struct isl_basic_set *bset1, struct isl_basic_set *bset2)
+{
+ struct isl_ctx *ctx = NULL;
+ struct isl_vec *dir = NULL;
+ struct isl_mat *T = NULL;
+ struct isl_mat *T2 = NULL;
+ struct isl_basic_set *hull;
+ struct isl_set *set;
+
+ if (!bset1 || !bset2)
+ goto error;
+ ctx = bset1->ctx;
+ dir = valid_direction(isl_basic_set_copy(bset1),
+ isl_basic_set_copy(bset2));
+ if (!dir)
+ goto error;
+ T = isl_mat_alloc(bset1->ctx, dir->size, dir->size);
+ if (!T)
+ goto error;
+ isl_seq_cpy(T->row[0], dir->block.data, dir->size);
+ T = isl_mat_unimodular_complete(T, 1);
+ T2 = isl_mat_right_inverse(isl_mat_copy(T));
+
+ bset1 = homogeneous_map(bset1, isl_mat_copy(T2));
+ bset2 = homogeneous_map(bset2, T2);
+ set = isl_set_alloc_dim(isl_basic_set_get_dim(bset1), 2, 0);
+ set = isl_set_add_basic_set(set, bset1);
+ set = isl_set_add_basic_set(set, bset2);
+ hull = uset_convex_hull(set);
+ hull = isl_basic_set_preimage(hull, T);
+
+ isl_vec_free(dir);
+
+ return hull;
+error:
+ isl_vec_free(dir);
+ isl_basic_set_free(bset1);
+ isl_basic_set_free(bset2);
+ return NULL;
+}
+
+static struct isl_basic_set *uset_convex_hull_wrap(struct isl_set *set);
+static struct isl_basic_set *modulo_affine_hull(
+ struct isl_set *set, struct isl_basic_set *affine_hull);
+
+/* Compute the convex hull of a pair of basic sets without any parameters or
+ * integer divisions.
+ *
+ * This function is called from uset_convex_hull_unbounded, which
+ * means that the complete convex hull is unbounded. Some pairs
+ * of basic sets may still be bounded, though.
+ * They may even lie inside a lower dimensional space, in which
+ * case they need to be handled inside their affine hull since
+ * the main algorithm assumes that the result is full-dimensional.
+ *
+ * If the convex hull of the two basic sets would have a non-trivial
+ * lineality space, we first project out this lineality space.
+ */
+static struct isl_basic_set *convex_hull_pair(struct isl_basic_set *bset1,
+ struct isl_basic_set *bset2)
+{
+ isl_basic_set *lin, *aff;
+ int bounded1, bounded2;
+
+ aff = isl_set_affine_hull(isl_basic_set_union(isl_basic_set_copy(bset1),
+ isl_basic_set_copy(bset2)));
+ if (!aff)
+ goto error;
+ if (aff->n_eq != 0)
+ return modulo_affine_hull(isl_basic_set_union(bset1, bset2), aff);
+ isl_basic_set_free(aff);
+
+ bounded1 = isl_basic_set_is_bounded(bset1);
+ bounded2 = isl_basic_set_is_bounded(bset2);
+
+ if (bounded1 < 0 || bounded2 < 0)
+ goto error;
+
+ if (bounded1 && bounded2)
+ uset_convex_hull_wrap(isl_basic_set_union(bset1, bset2));
+
+ if (bounded1 || bounded2)
+ return convex_hull_pair_pointed(bset1, bset2);
+
+ lin = induced_lineality_space(isl_basic_set_copy(bset1),
+ isl_basic_set_copy(bset2));
+ if (!lin)
+ goto error;
+ if (isl_basic_set_is_universe(lin)) {
+ isl_basic_set_free(bset1);
+ isl_basic_set_free(bset2);
+ return lin;
+ }
+ if (lin->n_eq < isl_basic_set_total_dim(lin)) {
+ struct isl_set *set;
+ set = isl_set_alloc_dim(isl_basic_set_get_dim(bset1), 2, 0);
+ set = isl_set_add_basic_set(set, bset1);
+ set = isl_set_add_basic_set(set, bset2);
+ return modulo_lineality(set, lin);
+ }
+ isl_basic_set_free(lin);
+
+ return convex_hull_pair_pointed(bset1, bset2);
+error:
+ isl_basic_set_free(bset1);
+ isl_basic_set_free(bset2);
+ return NULL;
+}
+
+/* Compute the lineality space of a basic set.
+ * We currently do not allow the basic set to have any divs.
+ * We basically just drop the constants and turn every inequality
+ * into an equality.
+ */
+struct isl_basic_set *isl_basic_set_lineality_space(struct isl_basic_set *bset)
+{
+ int i, k;
+ struct isl_basic_set *lin = NULL;
+ unsigned dim;
+
+ if (!bset)
+ goto error;
+ isl_assert(bset->ctx, bset->n_div == 0, goto error);
+ dim = isl_basic_set_total_dim(bset);
+
+ lin = isl_basic_set_alloc_dim(isl_basic_set_get_dim(bset), 0, dim, 0);
+ if (!lin)
+ goto error;
+ for (i = 0; i < bset->n_eq; ++i) {
+ k = isl_basic_set_alloc_equality(lin);
+ if (k < 0)
+ goto error;
+ isl_int_set_si(lin->eq[k][0], 0);
+ isl_seq_cpy(lin->eq[k] + 1, bset->eq[i] + 1, dim);
+ }
+ lin = isl_basic_set_gauss(lin, NULL);
+ if (!lin)
+ goto error;
+ for (i = 0; i < bset->n_ineq && lin->n_eq < dim; ++i) {
+ k = isl_basic_set_alloc_equality(lin);
+ if (k < 0)
+ goto error;
+ isl_int_set_si(lin->eq[k][0], 0);
+ isl_seq_cpy(lin->eq[k] + 1, bset->ineq[i] + 1, dim);
+ lin = isl_basic_set_gauss(lin, NULL);
+ if (!lin)
+ goto error;
+ }
+ isl_basic_set_free(bset);
+ return lin;
+error:
+ isl_basic_set_free(lin);
+ isl_basic_set_free(bset);
+ return NULL;
+}
+
+/* Compute the (linear) hull of the lineality spaces of the basic sets in the
+ * "underlying" set "set".
+ */
+static struct isl_basic_set *uset_combined_lineality_space(struct isl_set *set)
+{
+ int i;
+ struct isl_set *lin = NULL;
+
+ if (!set)
+ return NULL;
+ if (set->n == 0) {
+ struct isl_dim *dim = isl_set_get_dim(set);
+ isl_set_free(set);
+ return isl_basic_set_empty(dim);
+ }
+
+ lin = isl_set_alloc_dim(isl_set_get_dim(set), set->n, 0);
+ for (i = 0; i < set->n; ++i)
+ lin = isl_set_add_basic_set(lin,
+ isl_basic_set_lineality_space(isl_basic_set_copy(set->p[i])));
+ isl_set_free(set);
+ return isl_set_affine_hull(lin);
+}
+
+/* Compute the convex hull of a set without any parameters or
+ * integer divisions.
+ * In each step, we combined two basic sets until only one
+ * basic set is left.
+ * The input basic sets are assumed not to have a non-trivial
+ * lineality space. If any of the intermediate results has
+ * a non-trivial lineality space, it is projected out.
+ */
+static struct isl_basic_set *uset_convex_hull_unbounded(struct isl_set *set)
+{
+ struct isl_basic_set *convex_hull = NULL;
+
+ convex_hull = isl_set_copy_basic_set(set);
+ set = isl_set_drop_basic_set(set, convex_hull);
+ if (!set)
+ goto error;
+ while (set->n > 0) {
+ struct isl_basic_set *t;
+ t = isl_set_copy_basic_set(set);
+ if (!t)
+ goto error;
+ set = isl_set_drop_basic_set(set, t);
+ if (!set)
+ goto error;
+ convex_hull = convex_hull_pair(convex_hull, t);
+ if (set->n == 0)
+ break;
+ t = isl_basic_set_lineality_space(isl_basic_set_copy(convex_hull));
+ if (!t)
+ goto error;
+ if (isl_basic_set_is_universe(t)) {
+ isl_basic_set_free(convex_hull);
+ convex_hull = t;
+ break;
+ }
+ if (t->n_eq < isl_basic_set_total_dim(t)) {
+ set = isl_set_add_basic_set(set, convex_hull);
+ return modulo_lineality(set, t);
+ }
+ isl_basic_set_free(t);
+ }
+ isl_set_free(set);
+ return convex_hull;
+error:
+ isl_set_free(set);
+ isl_basic_set_free(convex_hull);
+ return NULL;
+}
+
+/* Compute an initial hull for wrapping containing a single initial
+ * facet.
+ * This function assumes that the given set is bounded.
+ */
+static struct isl_basic_set *initial_hull(struct isl_basic_set *hull,
+ struct isl_set *set)
+{
+ struct isl_mat *bounds = NULL;
+ unsigned dim;
+ int k;
+
+ if (!hull)
+ goto error;
+ bounds = initial_facet_constraint(set);
+ if (!bounds)
+ goto error;
+ k = isl_basic_set_alloc_inequality(hull);
+ if (k < 0)
+ goto error;
+ dim = isl_set_n_dim(set);
+ isl_assert(set->ctx, 1 + dim == bounds->n_col, goto error);
+ isl_seq_cpy(hull->ineq[k], bounds->row[0], bounds->n_col);
+ isl_mat_free(bounds);
+
+ return hull;
+error:
+ isl_basic_set_free(hull);
+ isl_mat_free(bounds);
+ return NULL;
+}
+
+struct max_constraint {
+ struct isl_mat *c;
+ int count;
+ int ineq;
+};
+
+static int max_constraint_equal(const void *entry, const void *val)
+{
+ struct max_constraint *a = (struct max_constraint *)entry;
+ isl_int *b = (isl_int *)val;
+
+ return isl_seq_eq(a->c->row[0] + 1, b, a->c->n_col - 1);
+}
+
+static void update_constraint(struct isl_ctx *ctx, struct isl_hash_table *table,
+ isl_int *con, unsigned len, int n, int ineq)
+{
+ struct isl_hash_table_entry *entry;
+ struct max_constraint *c;
+ uint32_t c_hash;
+
+ c_hash = isl_seq_get_hash(con + 1, len);
+ entry = isl_hash_table_find(ctx, table, c_hash, max_constraint_equal,
+ con + 1, 0);
+ if (!entry)
+ return;
+ c = entry->data;
+ if (c->count < n) {
+ isl_hash_table_remove(ctx, table, entry);
+ return;
+ }
+ c->count++;
+ if (isl_int_gt(c->c->row[0][0], con[0]))
+ return;
+ if (isl_int_eq(c->c->row[0][0], con[0])) {
+ if (ineq)
+ c->ineq = ineq;
+ return;
+ }
+ c->c = isl_mat_cow(c->c);
+ isl_int_set(c->c->row[0][0], con[0]);
+ c->ineq = ineq;
+}
+
+/* Check whether the constraint hash table "table" constains the constraint
+ * "con".
+ */
+static int has_constraint(struct isl_ctx *ctx, struct isl_hash_table *table,
+ isl_int *con, unsigned len, int n)
+{
+ struct isl_hash_table_entry *entry;
+ struct max_constraint *c;
+ uint32_t c_hash;
+
+ c_hash = isl_seq_get_hash(con + 1, len);
+ entry = isl_hash_table_find(ctx, table, c_hash, max_constraint_equal,
+ con + 1, 0);
+ if (!entry)
+ return 0;
+ c = entry->data;
+ if (c->count < n)
+ return 0;