X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=isl_affine_hull.c;h=e71bc104b417ff8c58461061cf75bfb23cdf4ea4;hb=de51a9bc4da5dd3f1f9f57c2362da6f9752c44e0;hp=f2c67617e2db2adbe6f6d865e2e6e5310914e56d;hpb=4dab342ae5af2ca922fdc5b5a06eeac5e5ef5813;p=platform%2Fupstream%2Fisl.git

diff --git a/isl_affine_hull.c b/isl_affine_hull.c
index f2c6761..e71bc10 100644
--- a/isl_affine_hull.c
+++ b/isl_affine_hull.c
@@ -1,52 +1,77 @@
-#include "isl_ctx.h"
-#include "isl_seq.h"
-#include "isl_set.h"
-#include "isl_lp.h"
-#include "isl_map.h"
-#include "isl_map_private.h"
-
-struct isl_basic_map *isl_basic_map_affine_hull(struct isl_ctx *ctx,
+/*
+ * Copyright 2008-2009 Katholieke Universiteit Leuven
+ *
+ * Use of this software is governed by the MIT license
+ *
+ * Written by Sven Verdoolaege, K.U.Leuven, Departement
+ * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
+ */
+
+#include <isl_ctx_private.h>
+#include <isl_map_private.h>
+#include <isl/seq.h>
+#include <isl/set.h>
+#include <isl/lp.h>
+#include <isl/map.h>
+#include "isl_equalities.h"
+#include "isl_sample.h"
+#include "isl_tab.h"
+#include <isl_mat_private.h>
+
+struct isl_basic_map *isl_basic_map_implicit_equalities(
 						struct isl_basic_map *bmap)
 {
-	int i;
-	isl_int opt;
+	struct isl_tab *tab;
 
-	bmap = isl_basic_map_cow(ctx, bmap);
 	if (!bmap)
-		return NULL;
+		return bmap;
 
-	isl_int_init(opt);
-	for (i = 0; i < bmap->n_ineq; ++i) {
-		enum isl_lp_result res;
-		res = isl_solve_lp(bmap, 1, bmap->ineq[i]+1, ctx->one, &opt);
-		if (res == isl_lp_unbounded)
-			continue;
-		if (res == isl_lp_error)
-			goto error;
-		if (res == isl_lp_empty) {
-			bmap = isl_basic_map_set_to_empty(ctx, bmap);
-			break;
-		}
-		isl_int_add(opt, opt, bmap->ineq[i][0]);
-		if (isl_int_is_zero(opt)) {
-			isl_basic_map_inequality_to_equality(ctx, bmap, i);
-			--i;
-		}
-	}
-	isl_basic_map_free_inequality(ctx, bmap, bmap->n_ineq);
-	isl_int_clear(opt);
-	return isl_basic_map_finalize(ctx, bmap);
+	bmap = isl_basic_map_gauss(bmap, NULL);
+	if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_EMPTY))
+		return bmap;
+	if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_NO_IMPLICIT))
+		return bmap;
+	if (bmap->n_ineq <= 1)
+		return bmap;
+
+	tab = isl_tab_from_basic_map(bmap, 0);
+	if (isl_tab_detect_implicit_equalities(tab) < 0)
+		goto error;
+	bmap = isl_basic_map_update_from_tab(bmap, tab);
+	isl_tab_free(tab);
+	bmap = isl_basic_map_gauss(bmap, NULL);
+	ISL_F_SET(bmap, ISL_BASIC_MAP_NO_IMPLICIT);
+	return bmap;
 error:
-	isl_int_clear(opt);
-	isl_basic_map_free(ctx, bmap);
+	isl_tab_free(tab);
+	isl_basic_map_free(bmap);
 	return NULL;
 }
 
-struct isl_basic_set *isl_basic_set_affine_hull(struct isl_ctx *ctx,
+struct isl_basic_set *isl_basic_set_implicit_equalities(
 						struct isl_basic_set *bset)
 {
 	return (struct isl_basic_set *)
-		isl_basic_map_affine_hull(ctx, (struct isl_basic_map *)bset);
+		isl_basic_map_implicit_equalities((struct isl_basic_map*)bset);
+}
+
+struct isl_map *isl_map_implicit_equalities(struct isl_map *map)
+{
+	int i;
+
+	if (!map)
+		return map;
+
+	for (i = 0; i < map->n; ++i) {
+		map->p[i] = isl_basic_map_implicit_equalities(map->p[i]);
+		if (!map->p[i])
+			goto error;
+	}
+
+	return map;
+error:
+	isl_map_free(map);
+	return NULL;
 }
 
 /* Make eq[row][col] of both bmaps equal so we can add the row
@@ -55,42 +80,42 @@ struct isl_basic_set *isl_basic_set_affine_hull(struct isl_ctx *ctx,
  * after column col are zero.
  */
 static void set_common_multiple(
-	struct isl_basic_map *bmap1, struct isl_basic_map *bmap2,
+	struct isl_basic_set *bset1, struct isl_basic_set *bset2,
 	unsigned row, unsigned col)
 {
 	isl_int m, c;
 
-	if (isl_int_eq(bmap1->eq[row][col], bmap2->eq[row][col]))
+	if (isl_int_eq(bset1->eq[row][col], bset2->eq[row][col]))
 		return;
 
 	isl_int_init(c);
 	isl_int_init(m);
-	isl_int_lcm(m, bmap1->eq[row][col], bmap2->eq[row][col]);
-	isl_int_divexact(c, m, bmap1->eq[row][col]);
-	isl_seq_scale(bmap1->eq[row], bmap1->eq[row], c, col+1);
-	isl_int_divexact(c, m, bmap2->eq[row][col]);
-	isl_seq_scale(bmap2->eq[row], bmap2->eq[row], c, col+1);
+	isl_int_lcm(m, bset1->eq[row][col], bset2->eq[row][col]);
+	isl_int_divexact(c, m, bset1->eq[row][col]);
+	isl_seq_scale(bset1->eq[row], bset1->eq[row], c, col+1);
+	isl_int_divexact(c, m, bset2->eq[row][col]);
+	isl_seq_scale(bset2->eq[row], bset2->eq[row], c, col+1);
 	isl_int_clear(c);
 	isl_int_clear(m);
 }
 
 /* Delete a given equality, moving all the following equalities one up.
  */
-static void delete_row(struct isl_basic_map *bmap, unsigned row)
+static void delete_row(struct isl_basic_set *bset, unsigned row)
 {
 	isl_int *t;
 	int r;
 
-	t = bmap->eq[row];
-	bmap->n_eq--;
-	for (r = row; r < bmap->n_eq; ++r)
-		bmap->eq[r] = bmap->eq[r+1];
-	bmap->eq[bmap->n_eq] = t;
+	t = bset->eq[row];
+	bset->n_eq--;
+	for (r = row; r < bset->n_eq; ++r)
+		bset->eq[r] = bset->eq[r+1];
+	bset->eq[bset->n_eq] = t;
 }
 
-/* Make first row entries in column col of bmap1 identical to
- * those of bmap2, using the fact that entry bmap1->eq[row][col]=a
- * is non-zero.  Initially, these elements of bmap1 are all zero.
+/* Make first row entries in column col of bset1 identical to
+ * those of bset2, using the fact that entry bset1->eq[row][col]=a
+ * is non-zero.  Initially, these elements of bset1 are all zero.
  * For each row i < row, we set
  *		A[i] = a * A[i] + B[i][col] * A[row]
  *		B[i] = a * B[i]
@@ -98,7 +123,7 @@ static void delete_row(struct isl_basic_map *bmap, unsigned row)
  *		A[i][col] = B[i][col] = a * old(B[i][col])
  */
 static void construct_column(
-	struct isl_basic_map *bmap1, struct isl_basic_map *bmap2,
+	struct isl_basic_set *bset1, struct isl_basic_set *bset2,
 	unsigned row, unsigned col)
 {
 	int r;
@@ -108,24 +133,24 @@ static void construct_column(
 
 	isl_int_init(a);
 	isl_int_init(b);
-	total = 1 + bmap1->nparam + bmap1->n_in + bmap1->n_out + bmap1->n_div;
+	total = 1 + isl_basic_set_n_dim(bset1);
 	for (r = 0; r < row; ++r) {
-		if (isl_int_is_zero(bmap2->eq[r][col]))
+		if (isl_int_is_zero(bset2->eq[r][col]))
 			continue;
-		isl_int_gcd(b, bmap2->eq[r][col], bmap1->eq[row][col]);
-		isl_int_divexact(a, bmap1->eq[row][col], b);
-		isl_int_divexact(b, bmap2->eq[r][col], b);
-		isl_seq_combine(bmap1->eq[r], a, bmap1->eq[r],
-					      b, bmap1->eq[row], total);
-		isl_seq_scale(bmap2->eq[r], bmap2->eq[r], a, total);
+		isl_int_gcd(b, bset2->eq[r][col], bset1->eq[row][col]);
+		isl_int_divexact(a, bset1->eq[row][col], b);
+		isl_int_divexact(b, bset2->eq[r][col], b);
+		isl_seq_combine(bset1->eq[r], a, bset1->eq[r],
+					      b, bset1->eq[row], total);
+		isl_seq_scale(bset2->eq[r], bset2->eq[r], a, total);
 	}
 	isl_int_clear(a);
 	isl_int_clear(b);
-	delete_row(bmap1, row);
+	delete_row(bset1, row);
 }
 
-/* Make first row entries in column col of bmap1 identical to
- * those of bmap2, using only these entries of the two matrices.
+/* Make first row entries in column col of bset1 identical to
+ * those of bset2, using only these entries of the two matrices.
  * Let t be the last row with different entries.
  * For each row i < t, we set
  *	A[i] = (A[t][col]-B[t][col]) * A[i] + (B[i][col]-A[i][col) * A[t]
@@ -134,7 +159,7 @@ static void construct_column(
  *	A[i][col] = B[i][col] = old(A[t][col]*B[i][col]-A[i][col]*B[t][col])
  */
 static int transform_column(
-	struct isl_basic_map *bmap1, struct isl_basic_map *bmap2,
+	struct isl_basic_set *bset1, struct isl_basic_set *bset2,
 	unsigned row, unsigned col)
 {
 	int i, t;
@@ -142,31 +167,31 @@ static int transform_column(
 	unsigned total;
 
 	for (t = row-1; t >= 0; --t)
-		if (isl_int_ne(bmap1->eq[t][col], bmap2->eq[t][col]))
+		if (isl_int_ne(bset1->eq[t][col], bset2->eq[t][col]))
 			break;
 	if (t < 0)
 		return 0;
 
-	total = 1 + bmap1->nparam + bmap1->n_in + bmap1->n_out + bmap1->n_div;
+	total = 1 + isl_basic_set_n_dim(bset1);
 	isl_int_init(a);
 	isl_int_init(b);
 	isl_int_init(g);
-	isl_int_sub(b, bmap1->eq[t][col], bmap2->eq[t][col]);
+	isl_int_sub(b, bset1->eq[t][col], bset2->eq[t][col]);
 	for (i = 0; i < t; ++i) {
-		isl_int_sub(a, bmap2->eq[i][col], bmap1->eq[i][col]);
+		isl_int_sub(a, bset2->eq[i][col], bset1->eq[i][col]);
 		isl_int_gcd(g, a, b);
 		isl_int_divexact(a, a, g);
 		isl_int_divexact(g, b, g);
-		isl_seq_combine(bmap1->eq[i], g, bmap1->eq[i], a, bmap1->eq[t],
+		isl_seq_combine(bset1->eq[i], g, bset1->eq[i], a, bset1->eq[t],
 				total);
-		isl_seq_combine(bmap2->eq[i], g, bmap2->eq[i], a, bmap2->eq[t],
+		isl_seq_combine(bset2->eq[i], g, bset2->eq[i], a, bset2->eq[t],
 				total);
 	}
 	isl_int_clear(a);
 	isl_int_clear(b);
 	isl_int_clear(g);
-	delete_row(bmap1, t);
-	delete_row(bmap2, t);
+	delete_row(bset1, t);
+	delete_row(bset2, t);
 	return 1;
 }
 
@@ -175,84 +200,1044 @@ static int transform_column(
  * except that the echelon form we use starts from the last column
  * and that we are dealing with integer coefficients.
  */
-static struct isl_basic_map *affine_hull(struct isl_ctx *ctx,
-	struct isl_basic_map *bmap1, struct isl_basic_map *bmap2)
+static struct isl_basic_set *affine_hull(
+	struct isl_basic_set *bset1, struct isl_basic_set *bset2)
 {
 	unsigned total;
 	int col;
 	int row;
 
-	total = 1 + bmap1->nparam + bmap1->n_in + bmap1->n_out + bmap1->n_div;
+	if (!bset1 || !bset2)
+		goto error;
+
+	total = 1 + isl_basic_set_n_dim(bset1);
 
 	row = 0;
 	for (col = total-1; col >= 0; --col) {
-		int is_zero1 = row >= bmap1->n_eq ||
-			isl_int_is_zero(bmap1->eq[row][col]);
-		int is_zero2 = row >= bmap2->n_eq ||
-			isl_int_is_zero(bmap2->eq[row][col]);
+		int is_zero1 = row >= bset1->n_eq ||
+			isl_int_is_zero(bset1->eq[row][col]);
+		int is_zero2 = row >= bset2->n_eq ||
+			isl_int_is_zero(bset2->eq[row][col]);
 		if (!is_zero1 && !is_zero2) {
-			set_common_multiple(bmap1, bmap2, row, col);
+			set_common_multiple(bset1, bset2, row, col);
 			++row;
 		} else if (!is_zero1 && is_zero2) {
-			construct_column(bmap1, bmap2, row, col);
+			construct_column(bset1, bset2, row, col);
 		} else if (is_zero1 && !is_zero2) {
-			construct_column(bmap2, bmap1, row, col);
+			construct_column(bset2, bset1, row, col);
 		} else {
-			if (transform_column(bmap1, bmap2, row, col))
+			if (transform_column(bset1, bset2, row, col))
 				--row;
 		}
 	}
-	isl_basic_map_free(ctx, bmap2);
-	return bmap1;
+	isl_assert(bset1->ctx, row == bset1->n_eq, goto error);
+	isl_basic_set_free(bset2);
+	bset1 = isl_basic_set_normalize_constraints(bset1);
+	return bset1;
+error:
+	isl_basic_set_free(bset1);
+	isl_basic_set_free(bset2);
+	return NULL;
+}
+
+/* Find an integer point in the set represented by "tab"
+ * that lies outside of the equality "eq" e(x) = 0.
+ * If "up" is true, look for a point satisfying e(x) - 1 >= 0.
+ * Otherwise, look for a point satisfying -e(x) - 1 >= 0 (i.e., e(x) <= -1).
+ * The point, if found, is returned.
+ * If no point can be found, a zero-length vector is returned.
+ *
+ * Before solving an ILP problem, we first check if simply
+ * adding the normal of the constraint to one of the known
+ * integer points in the basic set represented by "tab"
+ * yields another point inside the basic set.
+ *
+ * The caller of this function ensures that the tableau is bounded or
+ * that tab->basis and tab->n_unbounded have been set appropriately.
+ */
+static struct isl_vec *outside_point(struct isl_tab *tab, isl_int *eq, int up)
+{
+	struct isl_ctx *ctx;
+	struct isl_vec *sample = NULL;
+	struct isl_tab_undo *snap;
+	unsigned dim;
+
+	if (!tab)
+		return NULL;
+	ctx = tab->mat->ctx;
+
+	dim = tab->n_var;
+	sample = isl_vec_alloc(ctx, 1 + dim);
+	if (!sample)
+		return NULL;
+	isl_int_set_si(sample->el[0], 1);
+	isl_seq_combine(sample->el + 1,
+		ctx->one, tab->bmap->sample->el + 1,
+		up ? ctx->one : ctx->negone, eq + 1, dim);
+	if (isl_basic_map_contains(tab->bmap, sample))
+		return sample;
+	isl_vec_free(sample);
+	sample = NULL;
+
+	snap = isl_tab_snap(tab);
+
+	if (!up)
+		isl_seq_neg(eq, eq, 1 + dim);
+	isl_int_sub_ui(eq[0], eq[0], 1);
+
+	if (isl_tab_extend_cons(tab, 1) < 0)
+		goto error;
+	if (isl_tab_add_ineq(tab, eq) < 0)
+		goto error;
+
+	sample = isl_tab_sample(tab);
+
+	isl_int_add_ui(eq[0], eq[0], 1);
+	if (!up)
+		isl_seq_neg(eq, eq, 1 + dim);
+
+	if (sample && isl_tab_rollback(tab, snap) < 0)
+		goto error;
+
+	return sample;
+error:
+	isl_vec_free(sample);
+	return NULL;
 }
 
-struct isl_basic_map *isl_map_affine_hull(struct isl_ctx *ctx,
-						struct isl_map *map)
+struct isl_basic_set *isl_basic_set_recession_cone(struct isl_basic_set *bset)
 {
 	int i;
-	struct isl_basic_map *bmap;
 
-	map = isl_map_compute_divs(ctx, map);
-	map = isl_map_cow(ctx, map);
-	if (!map)
+	bset = isl_basic_set_cow(bset);
+	if (!bset)
 		return NULL;
+	isl_assert(bset->ctx, bset->n_div == 0, goto error);
 
-	if (map->n == 0) {
-		bmap = isl_basic_map_empty(ctx,
-					    map->nparam, map->n_in, map->n_out);
-		isl_map_free(ctx, map);
+	for (i = 0; i < bset->n_eq; ++i)
+		isl_int_set_si(bset->eq[i][0], 0);
+
+	for (i = 0; i < bset->n_ineq; ++i)
+		isl_int_set_si(bset->ineq[i][0], 0);
+
+	ISL_F_CLR(bset, ISL_BASIC_SET_NO_IMPLICIT);
+	return isl_basic_set_implicit_equalities(bset);
+error:
+	isl_basic_set_free(bset);
+	return NULL;
+}
+
+__isl_give isl_set *isl_set_recession_cone(__isl_take isl_set *set)
+{
+	int i;
+
+	if (!set)
+		return NULL;
+	if (set->n == 0)
+		return set;
+
+	set = isl_set_remove_divs(set);
+	set = isl_set_cow(set);
+	if (!set)
+		return NULL;
+
+	for (i = 0; i < set->n; ++i) {
+		set->p[i] = isl_basic_set_recession_cone(set->p[i]);
+		if (!set->p[i])
+			goto error;
+	}
+
+	return set;
+error:
+	isl_set_free(set);
+	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
+ * in the current approximation and adding them to that approximation
+ * until no such points can be found any more.
+ *
+ * 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 __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;
+
+	if (!tab || !hull)
+		goto error;
+
+	dim = tab->n_var;
+
+	if (isl_tab_extend_cons(tab, 2 * dim + 1) < 0)
+		goto error;
+
+	for (i = 0; i < dim; ++i) {
+		struct isl_vec *sample;
+		struct isl_basic_set *point;
+		for (j = 0; j < hull->n_eq; ++j) {
+			sample = outside_point(tab, hull->eq[j], 1);
+			if (!sample)
+				goto error;
+			if (sample->size > 0)
+				break;
+			isl_vec_free(sample);
+			sample = outside_point(tab, hull->eq[j], 0);
+			if (!sample)
+				goto error;
+			if (sample->size > 0)
+				break;
+			isl_vec_free(sample);
+
+			if (isl_tab_add_eq(tab, hull->eq[j]) < 0)
+				goto error;
+		}
+		if (j == hull->n_eq)
+			break;
+		if (tab->samples)
+			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 NULL;
+	}
+
+	return hull;
+error:
+	isl_basic_set_free(hull);
+	return NULL;
+}
+
+/* Drop all constraints in bmap that involve any of the dimensions
+ * first to first+n-1.
+ */
+static __isl_give isl_basic_map *isl_basic_map_drop_constraints_involving(
+	__isl_take isl_basic_map *bmap, unsigned first, unsigned n)
+{
+	int i;
+
+	if (n == 0)
 		return bmap;
+
+	bmap = isl_basic_map_cow(bmap);
+
+	if (!bmap)
+		return NULL;
+
+	for (i = bmap->n_eq - 1; i >= 0; --i) {
+		if (isl_seq_first_non_zero(bmap->eq[i] + 1 + first, n) == -1)
+			continue;
+		isl_basic_map_drop_equality(bmap, i);
+	}
+
+	for (i = bmap->n_ineq - 1; i >= 0; --i) {
+		if (isl_seq_first_non_zero(bmap->ineq[i] + 1 + first, n) == -1)
+			continue;
+		isl_basic_map_drop_inequality(bmap, i);
+	}
+
+	return bmap;
+}
+
+/* Drop all constraints in bset that involve any of the dimensions
+ * first to first+n-1.
+ */
+__isl_give isl_basic_set *isl_basic_set_drop_constraints_involving(
+	__isl_take isl_basic_set *bset, unsigned first, unsigned n)
+{
+	return isl_basic_map_drop_constraints_involving(bset, first, n);
+}
+
+/* Drop all constraints in bmap that do not involve any of the dimensions
+ * first to first + n - 1 of the given type.
+ */
+__isl_give isl_basic_map *isl_basic_map_drop_constraints_not_involving_dims(
+	__isl_take isl_basic_map *bmap,
+	enum isl_dim_type type, unsigned first, unsigned n)
+{
+	int i;
+	unsigned dim;
+
+	if (n == 0)
+		return isl_basic_map_set_to_empty(bmap);
+	bmap = isl_basic_map_cow(bmap);
+	if (!bmap)
+		return NULL;
+
+	dim = isl_basic_map_dim(bmap, type);
+	if (first + n > dim || first + n < first)
+		isl_die(isl_basic_map_get_ctx(bmap), isl_error_invalid,
+			"index out of bounds", return isl_basic_map_free(bmap));
+
+	first += isl_basic_map_offset(bmap, type) - 1;
+
+	for (i = bmap->n_eq - 1; i >= 0; --i) {
+		if (isl_seq_first_non_zero(bmap->eq[i] + 1 + first, n) != -1)
+			continue;
+		isl_basic_map_drop_equality(bmap, i);
 	}
 
-	for (i = 1; i < map->n; ++i)
-		map->p[0] = isl_basic_map_align_divs(ctx, map->p[0], map->p[i]);
-	for (i = 1; i < map->n; ++i)
-		map->p[i] = isl_basic_map_align_divs(ctx, map->p[i], map->p[0]);
+	for (i = bmap->n_ineq - 1; i >= 0; --i) {
+		if (isl_seq_first_non_zero(bmap->ineq[i] + 1 + first, n) != -1)
+			continue;
+		isl_basic_map_drop_inequality(bmap, i);
+	}
+
+	return bmap;
+}
+
+/* Drop all constraints in bset that do not involve any of the dimensions
+ * first to first + n - 1 of the given type.
+ */
+__isl_give isl_basic_set *isl_basic_set_drop_constraints_not_involving_dims(
+	__isl_take isl_basic_set *bset,
+	enum isl_dim_type type, unsigned first, unsigned n)
+{
+	return isl_basic_map_drop_constraints_not_involving_dims(bset,
+							    type, first, n);
+}
+
+/* Drop all constraints in bmap that involve any of the dimensions
+ * first to first + n - 1 of the given type.
+ */
+__isl_give isl_basic_map *isl_basic_map_drop_constraints_involving_dims(
+	__isl_take isl_basic_map *bmap,
+	enum isl_dim_type type, unsigned first, unsigned n)
+{
+	unsigned dim;
+
+	if (!bmap)
+		return NULL;
+	if (n == 0)
+		return bmap;
+
+	dim = isl_basic_map_dim(bmap, type);
+	if (first + n > dim || first + n < first)
+		isl_die(isl_basic_map_get_ctx(bmap), isl_error_invalid,
+			"index out of bounds", return isl_basic_map_free(bmap));
+
+	bmap = isl_basic_map_remove_divs_involving_dims(bmap, type, first, n);
+	first += isl_basic_map_offset(bmap, type) - 1;
+	return isl_basic_map_drop_constraints_involving(bmap, first, n);
+}
+
+/* Drop all constraints in bset that involve any of the dimensions
+ * first to first + n - 1 of the given type.
+ */
+__isl_give isl_basic_set *isl_basic_set_drop_constraints_involving_dims(
+	__isl_take isl_basic_set *bset,
+	enum isl_dim_type type, unsigned first, unsigned n)
+{
+	return isl_basic_map_drop_constraints_involving_dims(bset,
+							    type, first, n);
+}
+
+/* Drop all constraints in map that involve any of the dimensions
+ * first to first + n - 1 of the given type.
+ */
+__isl_give isl_map *isl_map_drop_constraints_involving_dims(
+	__isl_take isl_map *map,
+	enum isl_dim_type type, unsigned first, unsigned n)
+{
+	int i;
+	unsigned dim;
+
+	if (!map)
+		return NULL;
+	if (n == 0)
+		return map;
+
+	dim = isl_map_dim(map, type);
+	if (first + n > dim || first + n < first)
+		isl_die(isl_map_get_ctx(map), isl_error_invalid,
+			"index out of bounds", return isl_map_free(map));
+
+	map = isl_map_cow(map);
+	if (!map)
+		return NULL;
 
 	for (i = 0; i < map->n; ++i) {
-		map->p[i] = isl_basic_map_cow(ctx, map->p[i]);
-		map->p[i] = isl_basic_map_affine_hull(ctx, map->p[i]);
-		map->p[i] = isl_basic_map_gauss(ctx, map->p[i], NULL);
+		map->p[i] = isl_basic_map_drop_constraints_involving_dims(
+						    map->p[i], type, first, n);
 		if (!map->p[i])
+			return isl_map_free(map);
+	}
+
+	return map;
+}
+
+/* Drop all constraints in set that involve any of the dimensions
+ * first to first + n - 1 of the given type.
+ */
+__isl_give isl_set *isl_set_drop_constraints_involving_dims(
+	__isl_take isl_set *set,
+	enum isl_dim_type type, unsigned first, unsigned n)
+{
+	return isl_map_drop_constraints_involving_dims(set, type, first, n);
+}
+
+/* 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.
+ *
+ * The equalities are obtained by successively looking for
+ * a point that is affinely independent of the points found so far.
+ * In particular, for each equality satisfied by the points so far,
+ * we check if there is any point on a hyperplane parallel to the
+ * corresponding hyperplane shifted by at least one (in either direction).
+ */
+static struct isl_basic_set *uset_affine_hull_bounded(struct isl_basic_set *bset)
+{
+	struct isl_vec *sample = NULL;
+	struct isl_basic_set *hull;
+	struct isl_tab *tab = NULL;
+	unsigned dim;
+
+	if (isl_basic_set_plain_is_empty(bset))
+		return bset;
+
+	dim = isl_basic_set_n_dim(bset);
+
+	if (bset->sample && bset->sample->size == 1 + dim) {
+		int contains = isl_basic_set_contains(bset, bset->sample);
+		if (contains < 0)
 			goto error;
+		if (contains) {
+			if (dim == 0)
+				return bset;
+			sample = isl_vec_copy(bset->sample);
+		} else {
+			isl_vec_free(bset->sample);
+			bset->sample = NULL;
+		}
+	}
+
+	tab = isl_tab_from_basic_set(bset, 1);
+	if (!tab)
+		goto error;
+	if (tab->empty) {
+		isl_tab_free(tab);
+		isl_vec_free(sample);
+		return isl_basic_set_set_to_empty(bset);
+	}
+
+	if (!sample) {
+		struct isl_tab_undo *snap;
+		snap = isl_tab_snap(tab);
+		sample = isl_tab_sample(tab);
+		if (isl_tab_rollback(tab, snap) < 0)
+			goto error;
+		isl_vec_free(tab->bmap->sample);
+		tab->bmap->sample = isl_vec_copy(sample);
+	}
+
+	if (!sample)
+		goto error;
+	if (sample->size == 0) {
+		isl_tab_free(tab);
+		isl_vec_free(sample);
+		return isl_basic_set_set_to_empty(bset);
 	}
-	while (map->n > 1) {
-		map->p[0] = affine_hull(ctx, map->p[0], map->p[--map->n]);
-		if (!map->p[0])
+
+	hull = initialize_hull(bset, sample);
+
+	hull = extend_affine_hull(tab, hull, bset);
+	isl_basic_set_free(bset);
+	isl_tab_free(tab);
+
+	return hull;
+error:
+	isl_vec_free(sample);
+	isl_tab_free(tab);
+	isl_basic_set_free(bset);
+	return NULL;
+}
+
+/* Given an unbounded tableau and an integer point satisfying the tableau,
+ * construct an initial affine hull containing the recession cone
+ * shifted to the given point.
+ *
+ * The unbounded directions are taken from the last rows of the basis,
+ * which is assumed to have been initialized appropriately.
+ */
+static __isl_give isl_basic_set *initial_hull(struct isl_tab *tab,
+	__isl_take isl_vec *vec)
+{
+	int i;
+	int k;
+	struct isl_basic_set *bset = NULL;
+	struct isl_ctx *ctx;
+	unsigned dim;
+
+	if (!vec || !tab)
+		return NULL;
+	ctx = vec->ctx;
+	isl_assert(ctx, vec->size != 0, goto error);
+
+	bset = isl_basic_set_alloc(ctx, 0, vec->size - 1, 0, vec->size - 1, 0);
+	if (!bset)
+		goto error;
+	dim = isl_basic_set_n_dim(bset) - tab->n_unbounded;
+	for (i = 0; i < dim; ++i) {
+		k = isl_basic_set_alloc_equality(bset);
+		if (k < 0)
 			goto error;
+		isl_seq_cpy(bset->eq[k] + 1, tab->basis->row[1 + i] + 1,
+			    vec->size - 1);
+		isl_seq_inner_product(bset->eq[k] + 1, vec->el +1,
+				      vec->size - 1, &bset->eq[k][0]);
+		isl_int_neg(bset->eq[k][0], bset->eq[k][0]);
+	}
+	bset->sample = vec;
+	bset = isl_basic_set_gauss(bset, NULL);
+
+	return bset;
+error:
+	isl_basic_set_free(bset);
+	isl_vec_free(vec);
+	return NULL;
+}
+
+/* Given a tableau of a set and a tableau of the corresponding
+ * recession cone, detect and add all equalities to the tableau.
+ * If the tableau is bounded, then we can simply keep the
+ * tableau in its state after the return from extend_affine_hull.
+ * However, if the tableau is unbounded, then
+ * isl_tab_set_initial_basis_with_cone will add some additional
+ * constraints to the tableau that have to be removed again.
+ * In this case, we therefore rollback to the state before
+ * any constraints were added and then add the equalities back in.
+ */
+struct isl_tab *isl_tab_detect_equalities(struct isl_tab *tab,
+	struct isl_tab *tab_cone)
+{
+	int j;
+	struct isl_vec *sample;
+	struct isl_basic_set *hull = NULL;
+	struct isl_tab_undo *snap;
+
+	if (!tab || !tab_cone)
+		goto error;
+
+	snap = isl_tab_snap(tab);
+
+	isl_mat_free(tab->basis);
+	tab->basis = NULL;
+
+	isl_assert(tab->mat->ctx, tab->bmap, goto error);
+	isl_assert(tab->mat->ctx, tab->samples, goto error);
+	isl_assert(tab->mat->ctx, tab->samples->n_col == 1 + tab->n_var, goto error);
+	isl_assert(tab->mat->ctx, tab->n_sample > tab->n_outside, goto error);
+
+	if (isl_tab_set_initial_basis_with_cone(tab, tab_cone) < 0)
+		goto error;
+
+	sample = isl_vec_alloc(tab->mat->ctx, 1 + tab->n_var);
+	if (!sample)
+		goto error;
+
+	isl_seq_cpy(sample->el, tab->samples->row[tab->n_outside], sample->size);
+
+	isl_vec_free(tab->bmap->sample);
+	tab->bmap->sample = isl_vec_copy(sample);
+
+	if (tab->n_unbounded == 0)
+		hull = isl_basic_set_from_vec(isl_vec_copy(sample));
+	else
+		hull = initial_hull(tab, isl_vec_copy(sample));
+
+	for (j = tab->n_outside + 1; j < tab->n_sample; ++j) {
+		isl_seq_cpy(sample->el, tab->samples->row[j], sample->size);
+		hull = affine_hull(hull,
+				isl_basic_set_from_vec(isl_vec_copy(sample)));
+	}
+
+	isl_vec_free(sample);
+
+	hull = extend_affine_hull(tab, hull, NULL);
+	if (!hull)
+		goto error;
+
+	if (tab->n_unbounded == 0) {
+		isl_basic_set_free(hull);
+		return tab;
+	}
+
+	if (isl_tab_rollback(tab, snap) < 0)
+		goto error;
+
+	if (hull->n_eq > tab->n_zero) {
+		for (j = 0; j < hull->n_eq; ++j) {
+			isl_seq_normalize(tab->mat->ctx, hull->eq[j], 1 + tab->n_var);
+			if (isl_tab_add_eq(tab, hull->eq[j]) < 0)
+				goto error;
+		}
+	}
+
+	isl_basic_set_free(hull);
+
+	return tab;
+error:
+	isl_basic_set_free(hull);
+	isl_tab_free(tab);
+	return NULL;
+}
+
+/* Compute the affine hull of "bset", where "cone" is the recession cone
+ * of "bset".
+ *
+ * We first compute a unimodular transformation that puts the unbounded
+ * directions in the last dimensions.  In particular, we take a transformation
+ * that maps all equalities to equalities (in HNF) on the first dimensions.
+ * Let x be the original dimensions and y the transformed, with y_1 bounded
+ * and y_2 unbounded.
+ *
+ *	       [ y_1 ]			[ y_1 ]   [ Q_1 ]
+ *	x = U  [ y_2 ]			[ y_2 ] = [ Q_2 ] x
+ *
+ * Let's call the input basic set S.  We compute S' = preimage(S, U)
+ * and drop the final dimensions including any constraints involving them.
+ * This results in set S''.
+ * Then we compute the affine hull A'' of S''.
+ * Let F y_1 >= g be the constraint system of A''.  In the transformed
+ * space the y_2 are unbounded, so we can add them back without any constraints,
+ * resulting in
+ *
+ *		        [ y_1 ]
+ *		[ F 0 ] [ y_2 ] >= g
+ * or
+ *		        [ Q_1 ]
+ *		[ F 0 ] [ Q_2 ] x >= g
+ * or
+ *		F Q_1 x >= g
+ *
+ * The affine hull in the original space is then obtained as
+ * A = preimage(A'', Q_1).
+ */
+static struct isl_basic_set *affine_hull_with_cone(struct isl_basic_set *bset,
+	struct isl_basic_set *cone)
+{
+	unsigned total;
+	unsigned cone_dim;
+	struct isl_basic_set *hull;
+	struct isl_mat *M, *U, *Q;
+
+	if (!bset || !cone)
+		goto error;
+
+	total = isl_basic_set_total_dim(cone);
+	cone_dim = total - cone->n_eq;
+
+	M = isl_mat_sub_alloc6(bset->ctx, cone->eq, 0, cone->n_eq, 1, total);
+	M = isl_mat_left_hermite(M, 0, &U, &Q);
+	if (!M)
+		goto error;
+	isl_mat_free(M);
+
+	U = isl_mat_lin_to_aff(U);
+	bset = isl_basic_set_preimage(bset, isl_mat_copy(U));
+
+	bset = isl_basic_set_drop_constraints_involving(bset, total - cone_dim,
+							cone_dim);
+	bset = isl_basic_set_drop_dims(bset, total - cone_dim, cone_dim);
+
+	Q = isl_mat_lin_to_aff(Q);
+	Q = isl_mat_drop_rows(Q, 1 + total - cone_dim, cone_dim);
+
+	if (bset && bset->sample && bset->sample->size == 1 + total)
+		bset->sample = isl_mat_vec_product(isl_mat_copy(Q), bset->sample);
+
+	hull = uset_affine_hull_bounded(bset);
+
+	if (!hull) {
+		isl_mat_free(Q);
+		isl_mat_free(U);
+	} else {
+		struct isl_vec *sample = isl_vec_copy(hull->sample);
+		U = isl_mat_drop_cols(U, 1 + total - cone_dim, cone_dim);
+		if (sample && sample->size > 0)
+			sample = isl_mat_vec_product(U, sample);
+		else
+			isl_mat_free(U);
+		hull = isl_basic_set_preimage(hull, Q);
+		if (hull) {
+			isl_vec_free(hull->sample);
+			hull->sample = sample;
+		} else
+			isl_vec_free(sample);
+	}
+
+	isl_basic_set_free(cone);
+
+	return hull;
+error:
+	isl_basic_set_free(bset);
+	isl_basic_set_free(cone);
+	return NULL;
+}
+
+/* Look for all equalities satisfied by the integer points in bset,
+ * which is assumed not to have any explicit equalities.
+ *
+ * The equalities are obtained by successively looking for
+ * a point that is affinely independent of the points found so far.
+ * In particular, for each equality satisfied by the points so far,
+ * we check if there is any point on a hyperplane parallel to the
+ * corresponding hyperplane shifted by at least one (in either direction).
+ *
+ * Before looking for any outside points, we first compute the recession
+ * cone.  The directions of this recession cone will always be part
+ * of the affine hull, so there is no need for looking for any points
+ * in these directions.
+ * In particular, if the recession cone is full-dimensional, then
+ * the affine hull is simply the whole universe.
+ */
+static struct isl_basic_set *uset_affine_hull(struct isl_basic_set *bset)
+{
+	struct isl_basic_set *cone;
+
+	if (isl_basic_set_plain_is_empty(bset))
+		return bset;
+
+	cone = isl_basic_set_recession_cone(isl_basic_set_copy(bset));
+	if (!cone)
+		goto error;
+	if (cone->n_eq == 0) {
+		struct isl_basic_set *hull;
+		isl_basic_set_free(cone);
+		hull = isl_basic_set_universe_like(bset);
+		isl_basic_set_free(bset);
+		return hull;
+	}
+
+	if (cone->n_eq < isl_basic_set_total_dim(cone))
+		return affine_hull_with_cone(bset, cone);
+
+	isl_basic_set_free(cone);
+	return uset_affine_hull_bounded(bset);
+error:
+	isl_basic_set_free(bset);
+	return NULL;
+}
+
+/* Look for all equalities satisfied by the integer points in bmap
+ * that are independent of the equalities already explicitly available
+ * in bmap.
+ *
+ * We first remove all equalities already explicitly available,
+ * then look for additional equalities in the reduced space
+ * and then transform the result to the original space.
+ * The original equalities are _not_ added to this set.  This is
+ * the responsibility of the calling function.
+ * The resulting basic set has all meaning about the dimensions removed.
+ * In particular, dimensions that correspond to existential variables
+ * in bmap and that are found to be fixed are not removed.
+ */
+static struct isl_basic_set *equalities_in_underlying_set(
+						struct isl_basic_map *bmap)
+{
+	struct isl_mat *T1 = NULL;
+	struct isl_mat *T2 = NULL;
+	struct isl_basic_set *bset = NULL;
+	struct isl_basic_set *hull = NULL;
+
+	bset = isl_basic_map_underlying_set(bmap);
+	if (!bset)
+		return NULL;
+	if (bset->n_eq)
+		bset = isl_basic_set_remove_equalities(bset, &T1, &T2);
+	if (!bset)
+		goto error;
+
+	hull = uset_affine_hull(bset);
+	if (!T2)
+		return hull;
+
+	if (!hull) {
+		isl_mat_free(T1);
+		isl_mat_free(T2);
+	} else {
+		struct isl_vec *sample = isl_vec_copy(hull->sample);
+		if (sample && sample->size > 0)
+			sample = isl_mat_vec_product(T1, sample);
+		else
+			isl_mat_free(T1);
+		hull = isl_basic_set_preimage(hull, T2);
+		if (hull) {
+			isl_vec_free(hull->sample);
+			hull->sample = sample;
+		} else
+			isl_vec_free(sample);
+	}
+
+	return hull;
+error:
+	isl_mat_free(T1);
+	isl_mat_free(T2);
+	isl_basic_set_free(bset);
+	isl_basic_set_free(hull);
+	return NULL;
+}
+
+/* Detect and make explicit all equalities satisfied by the (integer)
+ * points in bmap.
+ */
+struct isl_basic_map *isl_basic_map_detect_equalities(
+						struct isl_basic_map *bmap)
+{
+	int i, j;
+	struct isl_basic_set *hull = NULL;
+
+	if (!bmap)
+		return NULL;
+	if (bmap->n_ineq == 0)
+		return bmap;
+	if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_EMPTY))
+		return bmap;
+	if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_ALL_EQUALITIES))
+		return bmap;
+	if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_RATIONAL))
+		return isl_basic_map_implicit_equalities(bmap);
+
+	hull = equalities_in_underlying_set(isl_basic_map_copy(bmap));
+	if (!hull)
+		goto error;
+	if (ISL_F_ISSET(hull, ISL_BASIC_SET_EMPTY)) {
+		isl_basic_set_free(hull);
+		return isl_basic_map_set_to_empty(bmap);
+	}
+	bmap = isl_basic_map_extend_space(bmap, isl_space_copy(bmap->dim), 0,
+					hull->n_eq, 0);
+	for (i = 0; i < hull->n_eq; ++i) {
+		j = isl_basic_map_alloc_equality(bmap);
+		if (j < 0)
+			goto error;
+		isl_seq_cpy(bmap->eq[j], hull->eq[i],
+				1 + isl_basic_set_total_dim(hull));
+	}
+	isl_vec_free(bmap->sample);
+	bmap->sample = isl_vec_copy(hull->sample);
+	isl_basic_set_free(hull);
+	ISL_F_SET(bmap, ISL_BASIC_MAP_NO_IMPLICIT | ISL_BASIC_MAP_ALL_EQUALITIES);
+	bmap = isl_basic_map_simplify(bmap);
+	return isl_basic_map_finalize(bmap);
+error:
+	isl_basic_set_free(hull);
+	isl_basic_map_free(bmap);
+	return NULL;
+}
+
+__isl_give isl_basic_set *isl_basic_set_detect_equalities(
+						__isl_take isl_basic_set *bset)
+{
+	return (isl_basic_set *)
+		isl_basic_map_detect_equalities((isl_basic_map *)bset);
+}
+
+__isl_give isl_map *isl_map_inline_foreach_basic_map(__isl_take isl_map *map,
+	__isl_give isl_basic_map *(*fn)(__isl_take isl_basic_map *bmap))
+{
+	struct isl_basic_map *bmap;
+	int i;
+
+	if (!map)
+		return NULL;
+
+	for (i = 0; i < map->n; ++i) {
+		bmap = isl_basic_map_copy(map->p[i]);
+		bmap = fn(bmap);
+		if (!bmap)
+			goto error;
+		isl_basic_map_free(map->p[i]);
+		map->p[i] = bmap;
+	}
+
+	return map;
+error:
+	isl_map_free(map);
+	return NULL;
+}
+
+__isl_give isl_map *isl_map_detect_equalities(__isl_take isl_map *map)
+{
+	return isl_map_inline_foreach_basic_map(map,
+					    &isl_basic_map_detect_equalities);
+}
+
+__isl_give isl_set *isl_set_detect_equalities(__isl_take isl_set *set)
+{
+	return (isl_set *)isl_map_detect_equalities((isl_map *)set);
+}
+
+/* After computing the rational affine hull (by detecting the implicit
+ * equalities), we compute the additional equalities satisfied by
+ * the integer points (if any) and add the original equalities back in.
+ */
+struct isl_basic_map *isl_basic_map_affine_hull(struct isl_basic_map *bmap)
+{
+	bmap = isl_basic_map_detect_equalities(bmap);
+	bmap = isl_basic_map_cow(bmap);
+	if (bmap)
+		isl_basic_map_free_inequality(bmap, bmap->n_ineq);
+	bmap = isl_basic_map_finalize(bmap);
+	return bmap;
+}
+
+struct isl_basic_set *isl_basic_set_affine_hull(struct isl_basic_set *bset)
+{
+	return (struct isl_basic_set *)
+		isl_basic_map_affine_hull((struct isl_basic_map *)bset);
+}
+
+struct isl_basic_map *isl_map_affine_hull(struct isl_map *map)
+{
+	int i;
+	struct isl_basic_map *model = NULL;
+	struct isl_basic_map *hull = NULL;
+	struct isl_set *set;
+
+	map = isl_map_detect_equalities(map);
+	map = isl_map_align_divs(map);
+
+	if (!map)
+		return NULL;
+
+	if (map->n == 0) {
+		hull = isl_basic_map_empty_like_map(map);
+		isl_map_free(map);
+		return hull;
+	}
+
+	model = isl_basic_map_copy(map->p[0]);
+	set = isl_map_underlying_set(map);
+	set = isl_set_cow(set);
+	if (!set)
+		goto error;
+
+	for (i = 0; i < set->n; ++i) {
+		set->p[i] = isl_basic_set_cow(set->p[i]);
+		set->p[i] = isl_basic_set_affine_hull(set->p[i]);
+		set->p[i] = isl_basic_set_gauss(set->p[i], NULL);
+		if (!set->p[i])
+			goto error;
+	}
+	set = isl_set_remove_empty_parts(set);
+	if (set->n == 0) {
+		hull = isl_basic_map_empty_like(model);
+		isl_basic_map_free(model);
+	} else {
+		struct isl_basic_set *bset;
+		while (set->n > 1) {
+			set->p[0] = affine_hull(set->p[0], set->p[--set->n]);
+			if (!set->p[0])
+				goto error;
+		}
+		bset = isl_basic_set_copy(set->p[0]);
+		hull = isl_basic_map_overlying_set(bset, model);
 	}
-	bmap = isl_basic_map_copy(ctx, map->p[0]);
-	isl_map_free(ctx, map);
-	bmap = isl_basic_map_finalize(ctx, bmap);
-	return isl_basic_map_simplify(ctx, bmap);
+	isl_set_free(set);
+	hull = isl_basic_map_simplify(hull);
+	return isl_basic_map_finalize(hull);
 error:
-	isl_map_free(ctx, map);
+	isl_basic_map_free(model);
+	isl_set_free(set);
 	return NULL;
 }
 
-struct isl_basic_set *isl_set_affine_hull(struct isl_ctx *ctx,
-						struct isl_set *set)
+struct isl_basic_set *isl_set_affine_hull(struct isl_set *set)
 {
 	return (struct isl_basic_set *)
-		isl_map_affine_hull(ctx, (struct isl_map *)set);
+		isl_map_affine_hull((struct isl_map *)set);
 }