return NULL;
}
+/* Move "sample" to a point that is one up (or down) from the original
+ * point in dimension "pos".
+ */
+static void adjacent_point(__isl_keep isl_vec *sample, int pos, int up)
+{
+ if (up)
+ isl_int_add_ui(sample->el[1 + pos], sample->el[1 + pos], 1);
+ else
+ isl_int_sub_ui(sample->el[1 + pos], sample->el[1 + pos], 1);
+}
+
+/* Check if any points that are adjacent to "sample" also belong to "bset".
+ * If so, add them to "hull" and return the updated hull.
+ *
+ * Before checking whether and adjacent point belongs to "bset", we first
+ * check whether it already belongs to "hull" as this test is typically
+ * much cheaper.
+ */
+static __isl_give isl_basic_set *add_adjacent_points(
+ __isl_take isl_basic_set *hull, __isl_take isl_vec *sample,
+ __isl_keep isl_basic_set *bset)
+{
+ int i, up;
+ int dim;
+
+ if (!sample)
+ goto error;
+
+ dim = isl_basic_set_dim(hull, isl_dim_set);
+
+ for (i = 0; i < dim; ++i) {
+ for (up = 0; up <= 1; ++up) {
+ int contains;
+ isl_basic_set *point;
+
+ adjacent_point(sample, i, up);
+ contains = isl_basic_set_contains(hull, sample);
+ if (contains < 0)
+ goto error;
+ if (contains) {
+ adjacent_point(sample, i, !up);
+ continue;
+ }
+ contains = isl_basic_set_contains(bset, sample);
+ if (contains < 0)
+ goto error;
+ if (contains) {
+ point = isl_basic_set_from_vec(
+ isl_vec_copy(sample));
+ hull = affine_hull(hull, point);
+ }
+ adjacent_point(sample, i, !up);
+ if (contains)
+ break;
+ }
+ }
+
+ isl_vec_free(sample);
+
+ return hull;
+error:
+ isl_vec_free(sample);
+ isl_basic_set_free(hull);
+ return NULL;
+}
+
/* Extend an initial (under-)approximation of the affine hull of basic
* set represented by the tableau "tab"
* by looking for points that do not satisfy one of the equalities
*
* The caller of this function ensures that "tab" is bounded or
* that tab->basis and tab->n_unbounded have been set appropriately.
+ *
+ * "bset" may be either NULL or the basic set represented by "tab".
+ * If "bset" is not NULL, we check for any point we find if any
+ * of its adjacent points also belong to "bset".
*/
-static struct isl_basic_set *extend_affine_hull(struct isl_tab *tab,
- struct isl_basic_set *hull)
+static __isl_give isl_basic_set *extend_affine_hull(struct isl_tab *tab,
+ __isl_take isl_basic_set *hull, __isl_keep isl_basic_set *bset)
{
int i, j;
unsigned dim;
tab = isl_tab_add_sample(tab, isl_vec_copy(sample));
if (!tab)
goto error;
+ if (bset)
+ hull = add_adjacent_points(hull, isl_vec_copy(sample),
+ bset);
point = isl_basic_set_from_vec(sample);
hull = affine_hull(hull, point);
if (!hull)
return bset;
}
+/* Construct an initial underapproximatino of the hull of "bset"
+ * from "sample" and any of its adjacent points that also belong to "bset".
+ */
+static __isl_give isl_basic_set *initialize_hull(__isl_keep isl_basic_set *bset,
+ __isl_take isl_vec *sample)
+{
+ isl_basic_set *hull;
+
+ hull = isl_basic_set_from_vec(isl_vec_copy(sample));
+ hull = add_adjacent_points(hull, sample, bset);
+
+ return hull;
+}
+
/* Look for all equalities satisfied by the integer points in bset,
* which is assumed to be bounded.
*
return isl_basic_set_set_to_empty(bset);
}
- hull = isl_basic_set_from_vec(sample);
+ hull = initialize_hull(bset, sample);
+ hull = extend_affine_hull(tab, hull, bset);
isl_basic_set_free(bset);
- hull = extend_affine_hull(tab, hull);
isl_tab_free(tab);
return hull;
isl_vec_free(sample);
- hull = extend_affine_hull(tab, hull);
+ hull = extend_affine_hull(tab, hull, NULL);
if (!hull)
goto error;