X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=isl_affine_hull.c;h=12fbad5d1bb14d412261c8f386bb9deae23a792c;hb=1815b1f908799391d4e87c2f73350885a693726b;hp=a1335984acf59223a242ddbc62169b0277452624;hpb=1453eb1ef0aff6fb416782c09a90eaf00914fb9a;p=platform%2Fupstream%2Fisl.git

diff --git a/isl_affine_hull.c b/isl_affine_hull.c
index a133598..12fbad5 100644
--- a/isl_affine_hull.c
+++ b/isl_affine_hull.c
@@ -1,12 +1,22 @@
-#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"
+/*
+ * 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)
@@ -24,13 +34,18 @@ struct isl_basic_map *isl_basic_map_implicit_equalities(
 	if (bmap->n_ineq <= 1)
 		return bmap;
 
-	tab = isl_tab_from_basic_map(bmap);
-	tab = isl_tab_detect_implicit_equalities(tab);
+	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_tab_free(tab);
+	isl_basic_map_free(bmap);
+	return NULL;
 }
 
 struct isl_basic_set *isl_basic_set_implicit_equalities(
@@ -192,6 +207,9 @@ static struct isl_basic_set *affine_hull(
 	int col;
 	int row;
 
+	if (!bset1 || !bset2)
+		goto error;
+
 	total = 1 + isl_basic_set_n_dim(bset1);
 
 	row = 0;
@@ -212,12 +230,13 @@ static struct isl_basic_set *affine_hull(
 				--row;
 		}
 	}
-	isl_basic_set_free(bset2);
 	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;
 }
 
@@ -239,10 +258,9 @@ error:
 static struct isl_vec *outside_point(struct isl_tab *tab, isl_int *eq, int up)
 {
 	struct isl_ctx *ctx;
-	struct isl_vec *sample;
+	struct isl_vec *sample = NULL;
 	struct isl_tab_undo *snap;
 	unsigned dim;
-	int k;
 
 	if (!tab)
 		return NULL;
@@ -254,9 +272,9 @@ static struct isl_vec *outside_point(struct isl_tab *tab, isl_int *eq, int up)
 		return NULL;
 	isl_int_set_si(sample->el[0], 1);
 	isl_seq_combine(sample->el + 1,
-		ctx->one, tab->bset->sample->el + 1,
+		ctx->one, tab->bmap->sample->el + 1,
 		up ? ctx->one : ctx->negone, eq + 1, dim);
-	if (isl_basic_set_contains(tab->bset, sample))
+	if (isl_basic_map_contains(tab->bmap, sample))
 		return sample;
 	isl_vec_free(sample);
 	sample = NULL;
@@ -269,7 +287,8 @@ static struct isl_vec *outside_point(struct isl_tab *tab, isl_int *eq, int up)
 
 	if (isl_tab_extend_cons(tab, 1) < 0)
 		goto error;
-	tab = isl_tab_add_ineq(tab, eq);
+	if (isl_tab_add_ineq(tab, eq) < 0)
+		goto error;
 
 	sample = isl_tab_sample(tab);
 
@@ -277,7 +296,7 @@ static struct isl_vec *outside_point(struct isl_tab *tab, isl_int *eq, int up)
 	if (!up)
 		isl_seq_neg(eq, eq, 1 + dim);
 
-	if (isl_tab_rollback(tab, snap) < 0)
+	if (sample && isl_tab_rollback(tab, snap) < 0)
 		goto error;
 
 	return sample;
@@ -308,6 +327,98 @@ error:
 	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
@@ -316,11 +427,15 @@ error:
  *
  * 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, k;
+	int i, j;
 	unsigned dim;
 
 	if (!tab || !hull)
@@ -348,8 +463,7 @@ static struct isl_basic_set *extend_affine_hull(struct isl_tab *tab,
 				break;
 			isl_vec_free(sample);
 
-			tab = isl_tab_add_eq(tab, hull->eq[j]);
-			if (!tab)
+			if (isl_tab_add_eq(tab, hull->eq[j]) < 0)
 				goto error;
 		}
 		if (j == hull->n_eq)
@@ -358,8 +472,13 @@ static struct isl_basic_set *extend_affine_hull(struct isl_tab *tab,
 			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;
@@ -368,32 +487,186 @@ error:
 	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.
  */
-static struct isl_basic_set *drop_constraints_involving
-	(struct isl_basic_set *bset, unsigned first, unsigned n)
+__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 (!bset)
+	if (n == 0)
+		return isl_basic_map_set_to_empty(bmap);
+	bmap = isl_basic_map_cow(bmap);
+	if (!bmap)
 		return NULL;
 
-	bset = isl_basic_set_cow(bset);
+	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 = bset->n_eq - 1; i >= 0; --i) {
-		if (isl_seq_first_non_zero(bset->eq[i] + 1 + first, n) == -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_set_drop_equality(bset, i);
+		isl_basic_map_drop_equality(bmap, i);
 	}
 
-	for (i = bset->n_ineq - 1; i >= 0; --i) {
-		if (isl_seq_first_non_zero(bset->ineq[i] + 1 + first, n) == -1)
+	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_set_drop_inequality(bset, i);
+		isl_basic_map_drop_inequality(bmap, i);
 	}
 
-	return bset;
+	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_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,
@@ -412,7 +685,7 @@ static struct isl_basic_set *uset_affine_hull_bounded(struct isl_basic_set *bset
 	struct isl_tab *tab = NULL;
 	unsigned dim;
 
-	if (isl_basic_set_fast_is_empty(bset))
+	if (isl_basic_set_plain_is_empty(bset))
 		return bset;
 
 	dim = isl_basic_set_n_dim(bset);
@@ -431,10 +704,14 @@ static struct isl_basic_set *uset_affine_hull_bounded(struct isl_basic_set *bset
 		}
 	}
 
-	tab = isl_tab_from_basic_set(bset);
+	tab = isl_tab_from_basic_set(bset, 1);
 	if (!tab)
 		goto error;
-	tab->bset = isl_basic_set_copy(bset);
+	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;
@@ -442,8 +719,8 @@ static struct isl_basic_set *uset_affine_hull_bounded(struct isl_basic_set *bset
 		sample = isl_tab_sample(tab);
 		if (isl_tab_rollback(tab, snap) < 0)
 			goto error;
-		isl_vec_free(tab->bset->sample);
-		tab->bset->sample = isl_vec_copy(sample);
+		isl_vec_free(tab->bmap->sample);
+		tab->bmap->sample = isl_vec_copy(sample);
 	}
 
 	if (!sample)
@@ -454,10 +731,10 @@ static struct isl_basic_set *uset_affine_hull_bounded(struct isl_basic_set *bset
 		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;
@@ -469,7 +746,7 @@ error:
 }
 
 /* Given an unbounded tableau and an integer point satisfying the tableau,
- * construct an intial affine hull containing the recession cone
+ * 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,
@@ -521,14 +798,14 @@ error:
  * 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 eqaulities back in.
+ * 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;
+	struct isl_basic_set *hull = NULL;
 	struct isl_tab_undo *snap;
 
 	if (!tab || !tab_cone)
@@ -539,7 +816,7 @@ struct isl_tab *isl_tab_detect_equalities(struct isl_tab *tab,
 	isl_mat_free(tab->basis);
 	tab->basis = NULL;
 
-	isl_assert(tab->mat->ctx, tab->bset, goto error);
+	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);
@@ -553,8 +830,8 @@ struct isl_tab *isl_tab_detect_equalities(struct isl_tab *tab,
 
 	isl_seq_cpy(sample->el, tab->samples->row[tab->n_outside], sample->size);
 
-	isl_vec_free(tab->bset->sample);
-	tab->bset->sample = isl_vec_copy(sample);
+	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));
@@ -569,7 +846,7 @@ struct isl_tab *isl_tab_detect_equalities(struct isl_tab *tab,
 
 	isl_vec_free(sample);
 
-	hull = extend_affine_hull(tab, hull);
+	hull = extend_affine_hull(tab, hull, NULL);
 	if (!hull)
 		goto error;
 
@@ -584,7 +861,8 @@ struct isl_tab *isl_tab_detect_equalities(struct isl_tab *tab,
 	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);
-			tab = isl_tab_add_eq(tab, hull->eq[j]);
+			if (isl_tab_add_eq(tab, hull->eq[j]) < 0)
+				goto error;
 		}
 	}
 
@@ -592,6 +870,7 @@ struct isl_tab *isl_tab_detect_equalities(struct isl_tab *tab,
 
 	return tab;
 error:
+	isl_basic_set_free(hull);
 	isl_tab_free(tab);
 	return NULL;
 }
@@ -641,7 +920,7 @@ static struct isl_basic_set *affine_hull_with_cone(struct isl_basic_set *bset,
 	total = isl_basic_set_total_dim(cone);
 	cone_dim = total - cone->n_eq;
 
-	M = isl_mat_sub_alloc(bset->ctx, cone->eq, 0, cone->n_eq, 1, total);
+	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;
@@ -650,7 +929,8 @@ static struct isl_basic_set *affine_hull_with_cone(struct isl_basic_set *bset,
 	U = isl_mat_lin_to_aff(U);
 	bset = isl_basic_set_preimage(bset, isl_mat_copy(U));
 
-	bset = drop_constraints_involving(bset, total - cone_dim, cone_dim);
+	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);
@@ -661,9 +941,10 @@ static struct isl_basic_set *affine_hull_with_cone(struct isl_basic_set *bset,
 
 	hull = uset_affine_hull_bounded(bset);
 
-	if (!hull)
+	if (!hull) {
+		isl_mat_free(Q);
 		isl_mat_free(U);
-	else {
+	} 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)
@@ -671,8 +952,11 @@ static struct isl_basic_set *affine_hull_with_cone(struct isl_basic_set *bset,
 		else
 			isl_mat_free(U);
 		hull = isl_basic_set_preimage(hull, Q);
-		isl_vec_free(hull->sample);
-		hull->sample = sample;
+		if (hull) {
+			isl_vec_free(hull->sample);
+			hull->sample = sample;
+		} else
+			isl_vec_free(sample);
 	}
 
 	isl_basic_set_free(cone);
@@ -704,7 +988,7 @@ static struct isl_basic_set *uset_affine_hull(struct isl_basic_set *bset)
 {
 	struct isl_basic_set *cone;
 
-	if (isl_basic_set_fast_is_empty(bset))
+	if (isl_basic_set_plain_is_empty(bset))
 		return bset;
 
 	cone = isl_basic_set_recession_cone(isl_basic_set_copy(bset));
@@ -761,21 +1045,26 @@ static struct isl_basic_set *equalities_in_underlying_set(
 	if (!T2)
 		return hull;
 
-	if (!hull)
+	if (!hull) {
 		isl_mat_free(T1);
-	else {
+		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);
-		isl_vec_free(hull->sample);
-		hull->sample = sample;
+		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);
@@ -809,7 +1098,7 @@ struct isl_basic_map *isl_basic_map_detect_equalities(
 		isl_basic_set_free(hull);
 		return isl_basic_map_set_to_empty(bmap);
 	}
-	bmap = isl_basic_map_extend_dim(bmap, isl_dim_copy(bmap->dim), 0,
+	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);
@@ -837,27 +1126,10 @@ __isl_give isl_basic_set *isl_basic_set_detect_equalities(
 		isl_basic_map_detect_equalities((isl_basic_map *)bset);
 }
 
-struct isl_map *isl_map_detect_equalities(struct isl_map *map)
+__isl_give isl_map *isl_map_detect_equalities(__isl_take isl_map *map)
 {
-	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 = isl_basic_map_detect_equalities(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;
+	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)
@@ -873,7 +1145,9 @@ 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);
-	isl_basic_map_free_inequality(bmap, bmap->n_ineq);
+	if (bmap)
+		isl_basic_map_free_inequality(bmap, bmap->n_ineq);
+	bmap = isl_basic_map_finalize(bmap);
 	return bmap;
 }
 
@@ -883,12 +1157,63 @@ struct isl_basic_set *isl_basic_set_affine_hull(struct isl_basic_set *bset)
 		isl_basic_map_affine_hull((struct isl_basic_map *)bset);
 }
 
-struct isl_basic_map *isl_map_affine_hull(struct isl_map *map)
+/* Compute the affine hull of each basic map in "map" separately
+ * and call isl_basic_map_gauss on the result.
+ */
+static __isl_give isl_map *isl_map_local_affine_hull(__isl_take isl_map *map)
 {
 	int i;
+
+	map = isl_map_cow(map);
+	if (!map)
+		return NULL;
+
+	for (i = 0; i < map->n; ++i) {
+		map->p[i] = isl_basic_map_affine_hull(map->p[i]);
+		map->p[i] = isl_basic_map_gauss(map->p[i], NULL);
+		if (!map->p[i])
+			return isl_map_free(map);
+	}
+
+	return map;
+}
+
+static __isl_give isl_set *isl_set_local_affine_hull(__isl_take isl_set *set)
+{
+	return isl_map_local_affine_hull(set);
+}
+
+/* Compute the affine hull of "map".
+ *
+ * We first compute the affine hull of each basic map separately.
+ * Then we align the divs and recompute the affine hulls of the basic
+ * maps since some of them may now have extra divs.
+ * In order to avoid performing parametric integer programming to
+ * compute explicit expressions for the divs, possible leading to
+ * an explosion in the number of basic maps, we first drop all unknown
+ * divs before aligning the divs.  Note that the divs determined
+ * by an equality will be known since we call isl_basic_set_gauss
+ * from isl_map_local_affine_hull.  Calling gauss is also needed
+ * because affine_hull assumes its input has been gaussed, while
+ * isl_map_affine_hull may be called on input that has not been gaussed,
+ * in particular from initial_facet_constraint.
+ * Similarly, align_divs may reorder some divs so that we need to
+ * gauss the result again.
+ * Finally, we combine the individual affine hulls into a single
+ * affine hull.
+ */
+__isl_give isl_basic_map *isl_map_affine_hull(__isl_take isl_map *map)
+{
 	struct isl_basic_map *model = NULL;
 	struct isl_basic_map *hull = NULL;
 	struct isl_set *set;
+	isl_basic_set *bset;
+
+	map = isl_map_detect_equalities(map);
+	map = isl_map_local_affine_hull(map);
+	map = isl_map_remove_empty_parts(map);
+	map = isl_map_remove_unknown_divs(map);
+	map = isl_map_align_divs(map);
 
 	if (!map)
 		return NULL;
@@ -899,37 +1224,18 @@ struct isl_basic_map *isl_map_affine_hull(struct isl_map *map)
 		return hull;
 	}
 
-	map = isl_map_detect_equalities(map);
-	map = isl_map_align_divs(map);
-	if (!map)
-		return NULL;
 	model = isl_basic_map_copy(map->p[0]);
 	set = isl_map_underlying_set(map);
 	set = isl_set_cow(set);
+	set = isl_set_local_affine_hull(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);
-	}
+	while (set->n > 1)
+		set->p[0] = affine_hull(set->p[0], set->p[--set->n]);
+
+	bset = isl_basic_set_copy(set->p[0]);
+	hull = isl_basic_map_overlying_set(bset, model);
 	isl_set_free(set);
 	hull = isl_basic_map_simplify(hull);
 	return isl_basic_map_finalize(hull);