isl_map_simplify.c: eliminate_div: improve error handling

[isl.git] / isl_schedule.c

/*
 * Copyright 2011      INRIA Saclay
 * Copyright 2012-2014 Ecole Normale Superieure
 *
 * Use of this software is governed by the MIT license
 *
 * Written by Sven Verdoolaege, INRIA Saclay - Ile-de-France,
 * Parc Club Orsay Universite, ZAC des vignes, 4 rue Jacques Monod,
 * 91893 Orsay, France
 * and Ecole Normale Superieure, 45 rue d'Ulm, 75230 Paris, France
 */

#include <isl/ctx.h>
#include <isl_aff_private.h>
#include <isl/map.h>
#include <isl/set.h>
#include <isl/schedule.h>
#include <isl/schedule_node.h>
#include <isl_sort.h>
#include <isl_schedule_private.h>
#include <isl_schedule_tree.h>
#include <isl_schedule_node_private.h>
#include <isl_band_private.h>

/* Return a schedule encapsulating the given schedule tree.
 *
 * We currently only allow schedule trees with a domain or extension as root.
 *
 * The leaf field is initialized as a leaf node so that it can be
 * used to represent leaves in the constructed schedule.
 * The reference count is set to -1 since the isl_schedule_tree
 * should never be freed.  It is up to the (internal) users of
 * these leaves to ensure that they are only used while the schedule
 * is still alive.
 */
__isl_give isl_schedule *isl_schedule_from_schedule_tree(isl_ctx *ctx,
        __isl_take isl_schedule_tree *tree)
{
        enum isl_schedule_node_type type;
        isl_schedule *schedule;

        if (!tree)
                return NULL;
        type = isl_schedule_tree_get_type(tree);
        if (type != isl_schedule_node_domain &&
            type != isl_schedule_node_extension)
                isl_die(isl_schedule_tree_get_ctx(tree), isl_error_unsupported,
                        "root of schedule tree should be a domain or extension",
                        goto error);

        schedule = isl_calloc_type(ctx, isl_schedule);
        if (!schedule)
                goto error;

        schedule->leaf.ctx = ctx;
        isl_ctx_ref(ctx);
        schedule->ref = 1;
        schedule->root = tree;
        schedule->leaf.ref = -1;
        schedule->leaf.type = isl_schedule_node_leaf;

        return schedule;
error:
        isl_schedule_tree_free(tree);
        return NULL;
}

/* Return a pointer to a schedule with as single node
 * a domain node with the given domain.
 */
__isl_give isl_schedule *isl_schedule_from_domain(
        __isl_take isl_union_set *domain)
{
        isl_ctx *ctx;
        isl_schedule_tree *tree;

        ctx = isl_union_set_get_ctx(domain);
        tree = isl_schedule_tree_from_domain(domain);
        return isl_schedule_from_schedule_tree(ctx, tree);
}

/* Return a pointer to a schedule with as single node
 * a domain node with an empty domain.
 */
__isl_give isl_schedule *isl_schedule_empty(__isl_take isl_space *space)
{
        return isl_schedule_from_domain(isl_union_set_empty(space));
}

/* Return a new reference to "sched".
 */
__isl_give isl_schedule *isl_schedule_copy(__isl_keep isl_schedule *sched)
{
        if (!sched)
                return NULL;

        sched->ref++;
        return sched;
}

/* Return an isl_schedule that is equal to "schedule" and that has only
 * a single reference.
 *
 * We only need and support this function when the schedule is represented
 * as a schedule tree.
 */
__isl_give isl_schedule *isl_schedule_cow(__isl_take isl_schedule *schedule)
{
        isl_ctx *ctx;
        isl_schedule_tree *tree;

        if (!schedule)
                return NULL;
        if (schedule->ref == 1)
                return schedule;

        ctx = isl_schedule_get_ctx(schedule);
        if (!schedule->root)
                isl_die(ctx, isl_error_internal,
                        "only for schedule tree based schedules",
                        return isl_schedule_free(schedule));
        schedule->ref--;
        tree = isl_schedule_tree_copy(schedule->root);
        return isl_schedule_from_schedule_tree(ctx, tree);
}

__isl_null isl_schedule *isl_schedule_free(__isl_take isl_schedule *sched)
{
        if (!sched)
                return NULL;

        if (--sched->ref > 0)
                return NULL;

        isl_band_list_free(sched->band_forest);
        isl_schedule_tree_free(sched->root);
        isl_ctx_deref(sched->leaf.ctx);
        free(sched);
        return NULL;
}

/* Replace the root of "schedule" by "tree".
 */
__isl_give isl_schedule *isl_schedule_set_root(
        __isl_take isl_schedule *schedule, __isl_take isl_schedule_tree *tree)
{
        if (!schedule || !tree)
                goto error;
        if (schedule->root == tree) {
                isl_schedule_tree_free(tree);
                return schedule;
        }

        schedule = isl_schedule_cow(schedule);
        if (!schedule)
                goto error;
        isl_schedule_tree_free(schedule->root);
        schedule->root = tree;

        return schedule;
error:
        isl_schedule_free(schedule);
        isl_schedule_tree_free(tree);
        return NULL;
}

isl_ctx *isl_schedule_get_ctx(__isl_keep isl_schedule *schedule)
{
        return schedule ? schedule->leaf.ctx : NULL;
}

/* Return a pointer to the leaf of "schedule".
 *
 * Even though these leaves are not reference counted, we still
 * indicate that this function does not return a copy.
 */
__isl_keep isl_schedule_tree *isl_schedule_peek_leaf(
        __isl_keep isl_schedule *schedule)
{
        return schedule ? &schedule->leaf : NULL;
}

/* Are "schedule1" and "schedule2" obviously equal to each other?
 */
isl_bool isl_schedule_plain_is_equal(__isl_keep isl_schedule *schedule1,
        __isl_keep isl_schedule *schedule2)
{
        if (!schedule1 || !schedule2)
                return isl_bool_error;
        if (schedule1 == schedule2)
                return isl_bool_true;
        return isl_schedule_tree_plain_is_equal(schedule1->root,
                                                schedule2->root);
}

/* Return the (parameter) space of the schedule, i.e., the space
 * of the root domain.
 */
__isl_give isl_space *isl_schedule_get_space(
        __isl_keep isl_schedule *schedule)
{
        enum isl_schedule_node_type type;
        isl_space *space;
        isl_union_set *domain;

        if (!schedule)
                return NULL;
        if (!schedule->root)
                isl_die(isl_schedule_get_ctx(schedule), isl_error_invalid,
                        "schedule tree representation not available",
                        return NULL);
        type = isl_schedule_tree_get_type(schedule->root);
        if (type != isl_schedule_node_domain)
                isl_die(isl_schedule_get_ctx(schedule), isl_error_internal,
                        "root node not a domain node", return NULL);

        domain = isl_schedule_tree_domain_get_domain(schedule->root);
        space = isl_union_set_get_space(domain);
        isl_union_set_free(domain);

        return space;
}

/* Return a pointer to the root of "schedule".
 */
__isl_give isl_schedule_node *isl_schedule_get_root(
        __isl_keep isl_schedule *schedule)
{
        isl_ctx *ctx;
        isl_schedule_tree *tree;
        isl_schedule_tree_list *ancestors;

        if (!schedule)
                return NULL;

        if (!schedule->root)
                isl_die(isl_schedule_get_ctx(schedule), isl_error_invalid,
                        "schedule tree representation not available",
                        return NULL);

        ctx = isl_schedule_get_ctx(schedule);
        tree = isl_schedule_tree_copy(schedule->root);
        schedule = isl_schedule_copy(schedule);
        ancestors = isl_schedule_tree_list_alloc(ctx, 0);
        return isl_schedule_node_alloc(schedule, tree, ancestors, NULL);
}

/* Set max_out to the maximal number of output dimensions over
 * all maps.
 */
static isl_stat update_max_out(__isl_take isl_map *map, void *user)
{
        int *max_out = user;
        int n_out = isl_map_dim(map, isl_dim_out);

        if (n_out > *max_out)
                *max_out = n_out;

        isl_map_free(map);
        return isl_stat_ok;
}

/* Internal data structure for map_pad_range.
 *
 * "max_out" is the maximal schedule dimension.
 * "res" collects the results.
 */
struct isl_pad_schedule_map_data {
        int max_out;
        isl_union_map *res;
};

/* Pad the range of the given map with zeros to data->max_out and
 * then add the result to data->res.
 */
static isl_stat map_pad_range(__isl_take isl_map *map, void *user)
{
        struct isl_pad_schedule_map_data *data = user;
        int i;
        int n_out = isl_map_dim(map, isl_dim_out);

        map = isl_map_add_dims(map, isl_dim_out, data->max_out - n_out);
        for (i = n_out; i < data->max_out; ++i)
                map = isl_map_fix_si(map, isl_dim_out, i, 0);

        data->res = isl_union_map_add_map(data->res, map);
        if (!data->res)
                return isl_stat_error;

        return isl_stat_ok;
}

/* Pad the ranges of the maps in the union map with zeros such they all have
 * the same dimension.
 */
static __isl_give isl_union_map *pad_schedule_map(
        __isl_take isl_union_map *umap)
{
        struct isl_pad_schedule_map_data data;

        if (!umap)
                return NULL;
        if (isl_union_map_n_map(umap) <= 1)
                return umap;

        data.max_out = 0;
        if (isl_union_map_foreach_map(umap, &update_max_out, &data.max_out) < 0)
                return isl_union_map_free(umap);

        data.res = isl_union_map_empty(isl_union_map_get_space(umap));
        if (isl_union_map_foreach_map(umap, &map_pad_range, &data) < 0)
                data.res = isl_union_map_free(data.res);

        isl_union_map_free(umap);
        return data.res;
}

/* Return the domain of the root domain node of "schedule".
 */
__isl_give isl_union_set *isl_schedule_get_domain(
        __isl_keep isl_schedule *schedule)
{
        if (!schedule)
                return NULL;
        if (!schedule->root)
                isl_die(isl_schedule_get_ctx(schedule), isl_error_invalid,
                        "schedule tree representation not available",
                        return NULL);
        return isl_schedule_tree_domain_get_domain(schedule->root);
}

/* Traverse all nodes of "sched" in depth first preorder.
 *
 * If "fn" returns -1 on any of the nodes, then the traversal is aborted.
 * If "fn" returns 0 on any of the nodes, then the subtree rooted
 * at that node is skipped.
 *
 * Return 0 on success and -1 on failure.
 */
isl_stat isl_schedule_foreach_schedule_node(__isl_keep isl_schedule *sched,
        isl_bool (*fn)(__isl_keep isl_schedule_node *node, void *user),
        void *user)
{
        isl_schedule_node *node;
        isl_stat r;

        if (!sched)
                return isl_stat_error;

        node = isl_schedule_get_root(sched);
        r = isl_schedule_node_foreach_descendant(node, fn, user);
        isl_schedule_node_free(node);

        return r;
}

/* Traverse the node of "sched" in depth first postorder,
 * allowing the user to modify the visited node.
 * The traversal continues from the node returned by the callback function.
 * It is the responsibility of the user to ensure that this does not
 * lead to an infinite loop.  It is safest to always return a pointer
 * to the same position (same ancestors and child positions) as the input node.
 */
__isl_give isl_schedule *isl_schedule_map_schedule_node(
        __isl_take isl_schedule *schedule,
        __isl_give isl_schedule_node *(*fn)(
                __isl_take isl_schedule_node *node, void *user), void *user)
{
        isl_schedule_node *node;

        node = isl_schedule_get_root(schedule);
        isl_schedule_free(schedule);

        node = isl_schedule_node_map_descendant(node, fn, user);
        schedule = isl_schedule_node_get_schedule(node);
        isl_schedule_node_free(node);

        return schedule;
}

/* Wrapper around isl_schedule_node_reset_user for use as
 * an isl_schedule_map_schedule_node callback.
 */
static __isl_give isl_schedule_node *reset_user(
        __isl_take isl_schedule_node *node, void *user)
{
        return isl_schedule_node_reset_user(node);
}

/* Reset the user pointer on all identifiers of parameters and tuples
 * in the schedule "schedule".
 */
__isl_give isl_schedule *isl_schedule_reset_user(
        __isl_take isl_schedule *schedule)
{
        return isl_schedule_map_schedule_node(schedule, &reset_user, NULL);
}

/* Wrapper around isl_schedule_node_align_params for use as
 * an isl_schedule_map_schedule_node callback.
 */
static __isl_give isl_schedule_node *align_params(
        __isl_take isl_schedule_node *node, void *user)
{
        isl_space *space = user;

        return isl_schedule_node_align_params(node, isl_space_copy(space));
}

/* Align the parameters of all nodes in schedule "schedule"
 * to those of "space".
 */
__isl_give isl_schedule *isl_schedule_align_params(
        __isl_take isl_schedule *schedule, __isl_take isl_space *space)
{
        schedule = isl_schedule_map_schedule_node(schedule,
                                                    &align_params, space);
        isl_space_free(space);
        return schedule;
}

/* Wrapper around isl_schedule_node_pullback_union_pw_multi_aff for use as
 * an isl_schedule_map_schedule_node callback.
 */
static __isl_give isl_schedule_node *pullback_upma(
        __isl_take isl_schedule_node *node, void *user)
{
        isl_union_pw_multi_aff *upma = user;

        return isl_schedule_node_pullback_union_pw_multi_aff(node,
                                        isl_union_pw_multi_aff_copy(upma));
}

/* Compute the pullback of "schedule" by the function represented by "upma".
 * In other words, plug in "upma" in the iteration domains of "schedule".
 *
 * The schedule tree is not allowed to contain any expansion nodes.
 */
__isl_give isl_schedule *isl_schedule_pullback_union_pw_multi_aff(
        __isl_take isl_schedule *schedule,
        __isl_take isl_union_pw_multi_aff *upma)
{
        schedule = isl_schedule_map_schedule_node(schedule,
                                                &pullback_upma, upma);
        isl_union_pw_multi_aff_free(upma);
        return schedule;
}

/* Intersect the domain of the schedule "schedule" with "domain".
 * The root of "schedule" is required to be a domain node.
 */
__isl_give isl_schedule *isl_schedule_intersect_domain(
        __isl_take isl_schedule *schedule, __isl_take isl_union_set *domain)
{
        enum isl_schedule_node_type root_type;
        isl_schedule_node *node;

        if (!schedule || !domain)
                goto error;

        root_type = isl_schedule_tree_get_type(schedule->root);
        if (root_type != isl_schedule_node_domain)
                isl_die(isl_schedule_get_ctx(schedule), isl_error_invalid,
                        "root node must be a domain node", goto error);

        node = isl_schedule_get_root(schedule);
        isl_schedule_free(schedule);
        node = isl_schedule_node_domain_intersect_domain(node, domain);
        schedule = isl_schedule_node_get_schedule(node);
        isl_schedule_node_free(node);

        return schedule;
error:
        isl_schedule_free(schedule);
        isl_union_set_free(domain);
        return NULL;
}

/* Return an isl_union_map representation of the schedule.
 * If we still have access to the schedule tree, then we return
 * an isl_union_map corresponding to the subtree schedule of the child
 * of the root domain node.  That is, we do not intersect the domain
 * of the returned isl_union_map with the domain constraints.
 * Otherwise, we must have removed it because we created a band forest.
 * If so, we extract the isl_union_map from the forest.
 * This reconstructed schedule map
 * then needs to be padded with zeros to unify the schedule space
 * since the result of isl_band_list_get_suffix_schedule may not have
 * a unified schedule space.
 */
__isl_give isl_union_map *isl_schedule_get_map(__isl_keep isl_schedule *sched)
{
        enum isl_schedule_node_type type;
        isl_schedule_node *node;
        isl_union_map *umap;

        if (!sched)
                return NULL;

        if (sched->root) {
                type = isl_schedule_tree_get_type(sched->root);
                if (type != isl_schedule_node_domain)
                        isl_die(isl_schedule_get_ctx(sched), isl_error_internal,
                                "root node not a domain node", return NULL);

                node = isl_schedule_get_root(sched);
                node = isl_schedule_node_child(node, 0);
                umap = isl_schedule_node_get_subtree_schedule_union_map(node);
                isl_schedule_node_free(node);

                return umap;
        }

        umap = isl_band_list_get_suffix_schedule(sched->band_forest);
        return pad_schedule_map(umap);
}

static __isl_give isl_band_list *construct_band_list(
        __isl_take isl_schedule_node *node, __isl_take isl_union_set *domain,
        __isl_keep isl_band *parent);

/* Construct an isl_band structure from the given schedule tree node,
 * which may be either a band node or a leaf node.
 * In the latter case, construct a zero-dimensional band.
 * "domain" is the universe set of the domain elements that reach "node".
 * "parent" is the parent isl_band of the isl_band constructed
 * by this function.
 *
 * In case of a band node, we copy the properties (except tilability,
 * which is implicit in an isl_band) to the isl_band.
 * We assume that the band node is not zero-dimensional.
 * If the child of the band node is not a leaf node,
 * then we extract the children of the isl_band from this child.
 */
static __isl_give isl_band *construct_band(__isl_take isl_schedule_node *node,
        __isl_take isl_union_set *domain, __isl_keep isl_band *parent)
{
        int i;
        isl_ctx *ctx;
        isl_band *band = NULL;
        isl_multi_union_pw_aff *mupa;

        if (!node || !domain)
                goto error;

        ctx = isl_schedule_node_get_ctx(node);
        band = isl_band_alloc(ctx);
        if (!band)
                goto error;

        band->schedule = node->schedule;
        band->parent = parent;

        if (isl_schedule_node_get_type(node) == isl_schedule_node_leaf) {
                band->n = 0;
                band->pma = isl_union_pw_multi_aff_from_domain(domain);
                isl_schedule_node_free(node);
                return band;
        }

        band->n = isl_schedule_node_band_n_member(node);
        if (band->n == 0)
                isl_die(ctx, isl_error_unsupported,
                        "zero-dimensional band nodes not supported",
                        goto error);
        band->coincident = isl_alloc_array(ctx, int, band->n);
        if (band->n && !band->coincident)
                goto error;
        for (i = 0; i < band->n; ++i)
                band->coincident[i] =
                        isl_schedule_node_band_member_get_coincident(node, i);
        mupa = isl_schedule_node_band_get_partial_schedule(node);
        band->pma = isl_union_pw_multi_aff_from_multi_union_pw_aff(mupa);
        if (!band->pma)
                goto error;

        node = isl_schedule_node_child(node, 0);
        if (isl_schedule_node_get_type(node) == isl_schedule_node_leaf) {
                isl_schedule_node_free(node);
                isl_union_set_free(domain);
                return band;
        }

        band->children = construct_band_list(node, domain, band);
        if (!band->children)
                return isl_band_free(band);

        return band;
error:
        isl_union_set_free(domain);
        isl_schedule_node_free(node);
        isl_band_free(band);
        return NULL;
}

/* Construct a list of isl_band structures from the children of "node".
 * "node" itself is a sequence or set node, so that each of the child nodes
 * is a filter node and the list returned by node_construct_band_list
 * consists of a single element.
 * "domain" is the universe set of the domain elements that reach "node".
 * "parent" is the parent isl_band of the isl_band structures constructed
 * by this function.
 */
static __isl_give isl_band_list *construct_band_list_from_children(
        __isl_take isl_schedule_node *node, __isl_take isl_union_set *domain,
        __isl_keep isl_band *parent)
{
        int i, n;
        isl_ctx *ctx;
        isl_band_list *list;

        n = isl_schedule_node_n_children(node);

        ctx = isl_schedule_node_get_ctx(node);
        list = isl_band_list_alloc(ctx, 0);
        for (i = 0; i < n; ++i) {
                isl_schedule_node *child;
                isl_band_list *list_i;

                child = isl_schedule_node_get_child(node, i);
                list_i = construct_band_list(child, isl_union_set_copy(domain),
                                                parent);
                list = isl_band_list_concat(list, list_i);
        }

        isl_union_set_free(domain);
        isl_schedule_node_free(node);

        return list;
}

/* Construct an isl_band structure from the given sequence node
 * (or set node that is treated as a sequence node).
 * A single-dimensional band is created with as schedule for each of
 * filters of the children, the corresponding child position.
 * "domain" is the universe set of the domain elements that reach "node".
 * "parent" is the parent isl_band of the isl_band constructed
 * by this function.
 */
static __isl_give isl_band_list *construct_band_list_sequence(
        __isl_take isl_schedule_node *node, __isl_take isl_union_set *domain,
        __isl_keep isl_band *parent)
{
        int i, n;
        isl_ctx *ctx;
        isl_band *band = NULL;
        isl_space *space;
        isl_union_pw_multi_aff *upma;

        if (!node || !domain)
                goto error;

        ctx = isl_schedule_node_get_ctx(node);
        band = isl_band_alloc(ctx);
        if (!band)
                goto error;

        band->schedule = node->schedule;
        band->parent = parent;
        band->n = 1;
        band->coincident = isl_calloc_array(ctx, int, band->n);
        if (!band->coincident)
                goto error;

        n = isl_schedule_node_n_children(node);
        space = isl_union_set_get_space(domain);
        upma = isl_union_pw_multi_aff_empty(isl_space_copy(space));

        space = isl_space_set_from_params(space);
        space = isl_space_add_dims(space, isl_dim_set, 1);

        for (i = 0; i < n; ++i) {
                isl_schedule_node *child;
                isl_union_set *filter;
                isl_val *v;
                isl_val_list *vl;
                isl_multi_val *mv;
                isl_union_pw_multi_aff *upma_i;

                child = isl_schedule_node_get_child(node, i);
                filter = isl_schedule_node_filter_get_filter(child);
                isl_schedule_node_free(child);
                filter = isl_union_set_intersect(filter,
                                                isl_union_set_copy(domain));
                v = isl_val_int_from_si(ctx, i);
                vl = isl_val_list_from_val(v);
                mv = isl_multi_val_from_val_list(isl_space_copy(space), vl);
                upma_i = isl_union_pw_multi_aff_multi_val_on_domain(filter, mv);
                upma = isl_union_pw_multi_aff_union_add(upma, upma_i);
        }

        isl_space_free(space);

        band->pma = upma;
        if (!band->pma)
                goto error;

        band->children = construct_band_list_from_children(node, domain, band);
        if (!band->children)
                band = isl_band_free(band);
        return isl_band_list_from_band(band);
error:
        isl_union_set_free(domain);
        isl_schedule_node_free(node);
        isl_band_free(band);
        return NULL;
}

/* Construct a list of isl_band structures from "node" depending
 * on the type of "node".
 * "domain" is the universe set of the domain elements that reach "node".
 * "parent" is the parent isl_band of the isl_band structures constructed
 * by this function.
 *
 * If schedule_separate_components is set then set nodes are treated
 * as sequence nodes.  Otherwise, we directly extract an (implicitly
 * parallel) list of isl_band structures.
 *
 * If "node" is a filter, then "domain" is updated by the filter.
 */
static __isl_give isl_band_list *construct_band_list(
        __isl_take isl_schedule_node *node, __isl_take isl_union_set *domain,
        __isl_keep isl_band *parent)
{
        enum isl_schedule_node_type type;
        isl_ctx *ctx;
        isl_band *band;
        isl_band_list *list;
        isl_union_set *filter;

        if (!node || !domain)
                goto error;

        type = isl_schedule_node_get_type(node);
        switch (type) {
        case isl_schedule_node_error:
                goto error;
        case isl_schedule_node_context:
                isl_die(isl_schedule_node_get_ctx(node), isl_error_unsupported,
                        "context nodes not supported", goto error);
        case isl_schedule_node_domain:
                isl_die(isl_schedule_node_get_ctx(node), isl_error_invalid,
                        "internal domain nodes not allowed", goto error);
        case isl_schedule_node_expansion:
                isl_die(isl_schedule_node_get_ctx(node), isl_error_unsupported,
                        "expansion nodes not supported", goto error);
        case isl_schedule_node_extension:
                isl_die(isl_schedule_node_get_ctx(node), isl_error_unsupported,
                        "extension nodes not supported", goto error);
        case isl_schedule_node_filter:
                filter = isl_schedule_node_filter_get_filter(node);
                domain = isl_union_set_intersect(domain, filter);
                node = isl_schedule_node_child(node, 0);
                return construct_band_list(node, domain, parent);
        case isl_schedule_node_guard:
                isl_die(isl_schedule_node_get_ctx(node), isl_error_unsupported,
                        "guard nodes not supported", goto error);
        case isl_schedule_node_mark:
                isl_die(isl_schedule_node_get_ctx(node), isl_error_unsupported,
                        "mark nodes not supported", goto error);
        case isl_schedule_node_set:
                ctx = isl_schedule_node_get_ctx(node);
                if (isl_options_get_schedule_separate_components(ctx))
                        return construct_band_list_sequence(node, domain,
                                                            parent);
                else
                        return construct_band_list_from_children(node, domain,
                                                            parent);
        case isl_schedule_node_sequence:
                return construct_band_list_sequence(node, domain, parent);
        case isl_schedule_node_leaf:
        case isl_schedule_node_band:
                band = construct_band(node, domain, parent);
                list = isl_band_list_from_band(band);
                break;
        }

        return list;
error:
        isl_union_set_free(domain);
        isl_schedule_node_free(node);
        return NULL;
}

/* Return the roots of a band forest representation of the schedule.
 * The band forest is constructed from the schedule tree,
 * but once such a band forest is
 * constructed, we forget about the original schedule tree since
 * the user may modify the schedule through the band forest.
 */
__isl_give isl_band_list *isl_schedule_get_band_forest(
        __isl_keep isl_schedule *schedule)
{
        isl_schedule_node *node;
        isl_union_set *domain;

        if (!schedule)
                return NULL;
        if (schedule->root) {
                node = isl_schedule_get_root(schedule);
                domain = isl_schedule_node_domain_get_domain(node);
                domain = isl_union_set_universe(domain);
                node = isl_schedule_node_child(node, 0);

                schedule->band_forest = construct_band_list(node, domain, NULL);
                schedule->root = isl_schedule_tree_free(schedule->root);
        }
        return isl_band_list_dup(schedule->band_forest);
}

/* Call "fn" on each band in the schedule in depth-first post-order.
 */
int isl_schedule_foreach_band(__isl_keep isl_schedule *sched,
        int (*fn)(__isl_keep isl_band *band, void *user), void *user)
{
        int r;
        isl_band_list *forest;

        if (!sched)
                return -1;

        forest = isl_schedule_get_band_forest(sched);
        r = isl_band_list_foreach_band(forest, fn, user);
        isl_band_list_free(forest);

        return r;
}

static __isl_give isl_printer *print_band_list(__isl_take isl_printer *p,
        __isl_keep isl_band_list *list);

static __isl_give isl_printer *print_band(__isl_take isl_printer *p,
        __isl_keep isl_band *band)
{
        isl_band_list *children;

        p = isl_printer_start_line(p);
        p = isl_printer_print_union_pw_multi_aff(p, band->pma);
        p = isl_printer_end_line(p);

        if (!isl_band_has_children(band))
                return p;

        children = isl_band_get_children(band);

        p = isl_printer_indent(p, 4);
        p = print_band_list(p, children);
        p = isl_printer_indent(p, -4);

        isl_band_list_free(children);

        return p;
}

static __isl_give isl_printer *print_band_list(__isl_take isl_printer *p,
        __isl_keep isl_band_list *list)
{
        int i, n;

        n = isl_band_list_n_band(list);
        for (i = 0; i < n; ++i) {
                isl_band *band;
                band = isl_band_list_get_band(list, i);
                p = print_band(p, band);
                isl_band_free(band);
        }

        return p;
}

/* Insert a band node with partial schedule "partial" between the domain
 * root node of "schedule" and its single child.
 * Return a pointer to the updated schedule.
 *
 * If any of the nodes in the tree depend on the set of outer band nodes
 * then we refuse to insert the band node.
 */
__isl_give isl_schedule *isl_schedule_insert_partial_schedule(
        __isl_take isl_schedule *schedule,
        __isl_take isl_multi_union_pw_aff *partial)
{
        isl_schedule_node *node;
        int anchored;

        node = isl_schedule_get_root(schedule);
        isl_schedule_free(schedule);
        if (!node)
                goto error;
        if (isl_schedule_node_get_type(node) != isl_schedule_node_domain)
                isl_die(isl_schedule_node_get_ctx(node), isl_error_internal,
                        "root node not a domain node", goto error);

        node = isl_schedule_node_child(node, 0);
        anchored = isl_schedule_node_is_subtree_anchored(node);
        if (anchored < 0)
                goto error;
        if (anchored)
                isl_die(isl_schedule_node_get_ctx(node), isl_error_invalid,
                        "cannot insert band node in anchored subtree",
                        goto error);
        node = isl_schedule_node_insert_partial_schedule(node, partial);

        schedule = isl_schedule_node_get_schedule(node);
        isl_schedule_node_free(node);

        return schedule;
error:
        isl_schedule_node_free(node);
        isl_multi_union_pw_aff_free(partial);
        return NULL;
}

/* Insert a context node with constraints "context" between the domain
 * root node of "schedule" and its single child.
 * Return a pointer to the updated schedule.
 */
__isl_give isl_schedule *isl_schedule_insert_context(
        __isl_take isl_schedule *schedule, __isl_take isl_set *context)
{
        isl_schedule_node *node;

        node = isl_schedule_get_root(schedule);
        isl_schedule_free(schedule);
        node = isl_schedule_node_child(node, 0);
        node = isl_schedule_node_insert_context(node, context);
        schedule = isl_schedule_node_get_schedule(node);
        isl_schedule_node_free(node);

        return schedule;
}

/* Insert a guard node with constraints "guard" between the domain
 * root node of "schedule" and its single child.
 * Return a pointer to the updated schedule.
 */
__isl_give isl_schedule *isl_schedule_insert_guard(
        __isl_take isl_schedule *schedule, __isl_take isl_set *guard)
{
        isl_schedule_node *node;

        node = isl_schedule_get_root(schedule);
        isl_schedule_free(schedule);
        node = isl_schedule_node_child(node, 0);
        node = isl_schedule_node_insert_guard(node, guard);
        schedule = isl_schedule_node_get_schedule(node);
        isl_schedule_node_free(node);

        return schedule;
}

/* Return a tree with as top-level node a filter corresponding to "filter" and
 * as child, the (single) child of "tree".
 * However, if this single child is of type "type", then the filter is inserted
 * in the children of this single child instead.
 */
static __isl_give isl_schedule_tree *insert_filter_in_child_of_type(
        __isl_take isl_schedule_tree *tree, __isl_take isl_union_set *filter,
        enum isl_schedule_node_type type)
{
        if (!isl_schedule_tree_has_children(tree)) {
                isl_schedule_tree_free(tree);
                return isl_schedule_tree_from_filter(filter);
        } else {
                tree = isl_schedule_tree_child(tree, 0);
        }

        if (isl_schedule_tree_get_type(tree) == type)
                tree = isl_schedule_tree_children_insert_filter(tree, filter);
        else
                tree = isl_schedule_tree_insert_filter(tree, filter);

        return tree;
}

/* Construct a schedule that combines the schedules "schedule1" and "schedule2"
 * with a top-level node (underneath the domain node) of type "type",
 * either isl_schedule_node_sequence or isl_schedule_node_set.
 * The domains of the two schedules are assumed to be disjoint.
 *
 * The new schedule has as domain the union of the domains of the two
 * schedules.  The child of the domain node is a node of type "type"
 * with two filters corresponding to the domains of the input schedules.
 * If one (or both) of the top-level nodes of the two schedules is itself
 * of type "type", then the filter is pushed into the children of that
 * node and the sequence of set is flattened.
 */
__isl_give isl_schedule *isl_schedule_pair(enum isl_schedule_node_type type,
        __isl_take isl_schedule *schedule1, __isl_take isl_schedule *schedule2)
{
        int disjoint;
        isl_ctx *ctx;
        enum isl_schedule_node_type root_type;
        isl_schedule_tree *tree1, *tree2;
        isl_union_set *filter1, *filter2, *domain;

        if (!schedule1 || !schedule2)
                goto error;

        root_type = isl_schedule_tree_get_type(schedule1->root);
        if (root_type != isl_schedule_node_domain)
                isl_die(isl_schedule_get_ctx(schedule1), isl_error_internal,
                        "root node not a domain node", goto error);
        root_type = isl_schedule_tree_get_type(schedule2->root);
        if (root_type != isl_schedule_node_domain)
                isl_die(isl_schedule_get_ctx(schedule1), isl_error_internal,
                        "root node not a domain node", goto error);

        ctx = isl_schedule_get_ctx(schedule1);
        tree1 = isl_schedule_tree_copy(schedule1->root);
        filter1 = isl_schedule_tree_domain_get_domain(tree1);
        tree2 = isl_schedule_tree_copy(schedule2->root);
        filter2 = isl_schedule_tree_domain_get_domain(tree2);

        isl_schedule_free(schedule1);
        isl_schedule_free(schedule2);

        disjoint = isl_union_set_is_disjoint(filter1, filter2);
        if (disjoint < 0)
                filter1 = isl_union_set_free(filter1);
        if (!disjoint)
                isl_die(ctx, isl_error_invalid,
                        "schedule domains not disjoint",
                        filter1 = isl_union_set_free(filter1));

        domain = isl_union_set_union(isl_union_set_copy(filter1),
                                    isl_union_set_copy(filter2));
        filter1 = isl_union_set_gist(filter1, isl_union_set_copy(domain));
        filter2 = isl_union_set_gist(filter2, isl_union_set_copy(domain));

        tree1 = insert_filter_in_child_of_type(tree1, filter1, type);
        tree2 = insert_filter_in_child_of_type(tree2, filter2, type);

        tree1 = isl_schedule_tree_from_pair(type, tree1, tree2);
        tree1 = isl_schedule_tree_insert_domain(tree1, domain);

        return isl_schedule_from_schedule_tree(ctx, tree1);
error:
        isl_schedule_free(schedule1);
        isl_schedule_free(schedule2);
        return NULL;
}

/* Construct a schedule that combines the schedules "schedule1" and "schedule2"
 * through a sequence node.
 * The domains of the input schedules are assumed to be disjoint.
 */
__isl_give isl_schedule *isl_schedule_sequence(
        __isl_take isl_schedule *schedule1, __isl_take isl_schedule *schedule2)
{
        return isl_schedule_pair(isl_schedule_node_sequence,
                                schedule1, schedule2);
}

/* Construct a schedule that combines the schedules "schedule1" and "schedule2"
 * through a set node.
 * The domains of the input schedules are assumed to be disjoint.
 */
__isl_give isl_schedule *isl_schedule_set(
        __isl_take isl_schedule *schedule1, __isl_take isl_schedule *schedule2)
{
        return isl_schedule_pair(isl_schedule_node_set, schedule1, schedule2);
}

/* Print "schedule" to "p".
 *
 * If "schedule" was created from a schedule tree, then we print
 * the schedule tree representation.  Otherwise, we print
 * the band forest representation.
 */
__isl_give isl_printer *isl_printer_print_schedule(__isl_take isl_printer *p,
        __isl_keep isl_schedule *schedule)
{
        isl_band_list *forest;

        if (!schedule)
                return isl_printer_free(p);

        if (schedule->root)
                return isl_printer_print_schedule_tree(p, schedule->root);

        forest = isl_schedule_get_band_forest(schedule);

        p = print_band_list(p, forest);

        isl_band_list_free(forest);

        return p;
}

void isl_schedule_dump(__isl_keep isl_schedule *schedule)
{
        isl_printer *printer;

        if (!schedule)
                return;

        printer = isl_printer_to_file(isl_schedule_get_ctx(schedule), stderr);
        printer = isl_printer_set_yaml_style(printer, ISL_YAML_STYLE_BLOCK);
        printer = isl_printer_print_schedule(printer, schedule);

        isl_printer_free(printer);
}