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/*
 * Copyright 2008-2009 Katholieke Universiteit Leuven
 * Copyright 2010      INRIA Saclay
 *
 * Use of this software is governed by the GNU LGPLv2.1 license
 *
 * Written by Sven Verdoolaege, K.U.Leuven, Departement
 * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
 * and INRIA Saclay - Ile-de-France, Parc Club Orsay Universite,
 * ZAC des vignes, 4 rue Jacques Monod, 91893 Orsay, France 
 */

#include <isl_map_private.h>
#include <isl_constraint_private.h>
#include <isl_space_private.h>
#include <isl/seq.h>
#include <isl_aff_private.h>
#include <isl_local_space_private.h>

isl_ctx *isl_constraint_get_ctx(__isl_keep isl_constraint *c)
{
        return c ? isl_local_space_get_ctx(c->ls) : NULL;
}

static unsigned n(struct isl_constraint *c, enum isl_dim_type type)
{
        return isl_local_space_dim(c->ls, type);
}

static unsigned offset(struct isl_constraint *c, enum isl_dim_type type)
{
        return isl_local_space_offset(c->ls, type);
}

static unsigned basic_map_offset(__isl_keep isl_basic_map *bmap,
                                                        enum isl_dim_type type)
{
        return type == isl_dim_div ? 1 + isl_space_dim(bmap->dim, isl_dim_all)
                                   : 1 + isl_space_offset(bmap->dim, type);
}

static unsigned basic_set_offset(struct isl_basic_set *bset,
                                                        enum isl_dim_type type)
{
        isl_space *dim = bset->dim;
        switch (type) {
        case isl_dim_param:     return 1;
        case isl_dim_in:        return 1 + dim->nparam;
        case isl_dim_out:       return 1 + dim->nparam + dim->n_in;
        case isl_dim_div:       return 1 + dim->nparam + dim->n_in + dim->n_out;
        default:                return 0;
        }
}

__isl_give isl_constraint *isl_constraint_alloc_vec(int eq,
        __isl_take isl_local_space *ls, __isl_take isl_vec *v)
{
        isl_constraint *constraint;

        if (!ls || !v)
                goto error;

        constraint = isl_alloc_type(isl_vec_get_ctx(v), isl_constraint);
        if (!constraint)
                goto error;

        constraint->ref = 1;
        constraint->eq = eq;
        constraint->ls = ls;
        constraint->v = v;

        return constraint;
error:
        isl_local_space_free(ls);
        isl_vec_free(v);
        return NULL;
}

__isl_give isl_constraint *isl_constraint_alloc(int eq,
        __isl_take isl_local_space *ls)
{
        isl_ctx *ctx;
        isl_vec *v;

        if (!ls)
                return NULL;

        ctx = isl_local_space_get_ctx(ls);
        v = isl_vec_alloc(ctx, 1 + isl_local_space_dim(ls, isl_dim_all));
        v = isl_vec_clr(v);
        return isl_constraint_alloc_vec(eq, ls, v);
}

struct isl_constraint *isl_basic_map_constraint(struct isl_basic_map *bmap,
        isl_int **line)
{
        int eq;
        isl_ctx *ctx;
        isl_vec *v;
        isl_local_space *ls = NULL;
        isl_constraint *constraint;

        if (!bmap || !line)
                goto error;

        eq = line >= bmap->eq;

        ctx = isl_basic_map_get_ctx(bmap);
        ls = isl_basic_map_get_local_space(bmap);
        v = isl_vec_alloc(ctx, 1 + isl_local_space_dim(ls, isl_dim_all));
        if (!v)
                goto error;
        isl_seq_cpy(v->el, line[0], v->size);
        constraint = isl_constraint_alloc_vec(eq, ls, v);

        isl_basic_map_free(bmap);
        return constraint;
error:
        isl_local_space_free(ls);
        isl_basic_map_free(bmap);
        return NULL;
}

struct isl_constraint *isl_basic_set_constraint(struct isl_basic_set *bset,
        isl_int **line)
{
        return isl_basic_map_constraint((struct isl_basic_map *)bset, line);
}

__isl_give isl_constraint *isl_equality_alloc(__isl_take isl_local_space *ls)
{
        return isl_constraint_alloc(1, ls);
}

__isl_give isl_constraint *isl_inequality_alloc(__isl_take isl_local_space *ls)
{
        return isl_constraint_alloc(0, ls);
}

struct isl_constraint *isl_constraint_dup(struct isl_constraint *c)
{
        if (!c)
                return NULL;

        return isl_constraint_alloc_vec(c->eq, isl_local_space_copy(c->ls),
                                                isl_vec_copy(c->v));
}

struct isl_constraint *isl_constraint_cow(struct isl_constraint *c)
{
        if (!c)
                return NULL;

        if (c->ref == 1)
                return c;
        c->ref--;
        return isl_constraint_dup(c);
}

struct isl_constraint *isl_constraint_copy(struct isl_constraint *constraint)
{
        if (!constraint)
                return NULL;

        constraint->ref++;
        return constraint;
}

void *isl_constraint_free(struct isl_constraint *c)
{
        if (!c)
                return NULL;

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

        isl_local_space_free(c->ls);
        isl_vec_free(c->v);
        free(c);

        return NULL;
}

/* Return the number of constraints in "bset", i.e., the
 * number of times isl_basic_set_foreach_constraint will
 * call the callback.
 */
int isl_basic_set_n_constraint(__isl_keep isl_basic_set *bset)
{
        if (!bset)
                return -1;

        return bset->n_eq + bset->n_ineq;
}

int isl_basic_map_foreach_constraint(__isl_keep isl_basic_map *bmap,
        int (*fn)(__isl_take isl_constraint *c, void *user), void *user)
{
        int i;
        struct isl_constraint *c;

        if (!bmap)
                return -1;

        isl_assert(bmap->ctx, ISL_F_ISSET(bmap, ISL_BASIC_MAP_FINAL),
                        return -1);

        for (i = 0; i < bmap->n_eq; ++i) {
                c = isl_basic_map_constraint(isl_basic_map_copy(bmap),
                                                &bmap->eq[i]);
                if (!c)
                        return -1;
                if (fn(c, user) < 0)
                        return -1;
        }

        for (i = 0; i < bmap->n_ineq; ++i) {
                c = isl_basic_map_constraint(isl_basic_map_copy(bmap),
                                                &bmap->ineq[i]);
                if (!c)
                        return -1;
                if (fn(c, user) < 0)
                        return -1;
        }

        return 0;
}

int isl_basic_set_foreach_constraint(__isl_keep isl_basic_set *bset,
        int (*fn)(__isl_take isl_constraint *c, void *user), void *user)
{
        return isl_basic_map_foreach_constraint((isl_basic_map *)bset, fn, user);
}

int isl_constraint_is_equal(struct isl_constraint *constraint1,
        struct isl_constraint *constraint2)
{
        int equal;

        if (!constraint1 || !constraint2)
                return 0;
        if (constraint1->eq != constraint2->eq)
                return 0;
        equal = isl_local_space_is_equal(constraint1->ls, constraint2->ls);
        if (equal < 0 || !equal)
                return equal;
        return isl_vec_is_equal(constraint1->v, constraint2->v);
}

struct isl_basic_map *isl_basic_map_add_constraint(
        struct isl_basic_map *bmap, struct isl_constraint *constraint)
{
        isl_ctx *ctx;
        isl_space *dim;
        int equal_space;

        if (!bmap || !constraint)
                goto error;

        ctx = isl_constraint_get_ctx(constraint);
        dim = isl_constraint_get_space(constraint);
        equal_space = isl_space_is_equal(bmap->dim, dim);
        isl_space_free(dim);
        isl_assert(ctx, equal_space, goto error);

        bmap = isl_basic_map_intersect(bmap,
                                isl_basic_map_from_constraint(constraint));
        return bmap;
error:
        isl_basic_map_free(bmap);
        isl_constraint_free(constraint);
        return NULL;
}

struct isl_basic_set *isl_basic_set_add_constraint(
        struct isl_basic_set *bset, struct isl_constraint *constraint)
{
        return (struct isl_basic_set *)
                isl_basic_map_add_constraint((struct isl_basic_map *)bset,
                                                constraint);
}

__isl_give isl_map *isl_map_add_constraint(__isl_take isl_map *map,
        __isl_take isl_constraint *constraint)
{
        isl_basic_map *bmap;

        bmap = isl_basic_map_from_constraint(constraint);
        map = isl_map_intersect(map, isl_map_from_basic_map(bmap));

        return map;
}

__isl_give isl_set *isl_set_add_constraint(__isl_take isl_set *set,
        __isl_take isl_constraint *constraint)
{
        return isl_map_add_constraint(set, constraint);
}

__isl_give isl_space *isl_constraint_get_space(
        __isl_keep isl_constraint *constraint)
{
        return constraint ? isl_local_space_get_space(constraint->ls) : NULL;
}

__isl_give isl_local_space *isl_constraint_get_local_space(
        __isl_keep isl_constraint *constraint)
{
        return constraint ? isl_local_space_copy(constraint->ls) : NULL;
}

int isl_constraint_dim(struct isl_constraint *constraint,
        enum isl_dim_type type)
{
        if (!constraint)
                return -1;
        return n(constraint, type);
}

int isl_constraint_involves_dims(__isl_keep isl_constraint *constraint,
        enum isl_dim_type type, unsigned first, unsigned n)
{
        int i;
        isl_ctx *ctx;
        int *active = NULL;
        int involves = 0;

        if (!constraint)
                return -1;
        if (n == 0)
                return 0;

        ctx = isl_constraint_get_ctx(constraint);
        if (first + n > isl_constraint_dim(constraint, type))
                isl_die(ctx, isl_error_invalid,
                        "range out of bounds", return -1);

        active = isl_local_space_get_active(constraint->ls,
                                            constraint->v->el + 1);
        if (!active)
                goto error;

        first += isl_local_space_offset(constraint->ls, type) - 1;
        for (i = 0; i < n; ++i)
                if (active[first + i]) {
                        involves = 1;
                        break;
                }

        free(active);

        return involves;
error:
        free(active);
        return -1;
}

/* Does the given constraint represent a lower bound on the given
 * dimension?
 */
int isl_constraint_is_lower_bound(__isl_keep isl_constraint *constraint,
        enum isl_dim_type type, unsigned pos)
{
        if (!constraint)
                return -1;

        if (pos >= isl_local_space_dim(constraint->ls, type))
                isl_die(isl_constraint_get_ctx(constraint), isl_error_invalid,
                        "position out of bounds", return -1);

        pos += isl_local_space_offset(constraint->ls, type);
        return isl_int_is_pos(constraint->v->el[pos]);
}

/* Does the given constraint represent an upper bound on the given
 * dimension?
 */
int isl_constraint_is_upper_bound(__isl_keep isl_constraint *constraint,
        enum isl_dim_type type, unsigned pos)
{
        if (!constraint)
                return -1;

        if (pos >= isl_local_space_dim(constraint->ls, type))
                isl_die(isl_constraint_get_ctx(constraint), isl_error_invalid,
                        "position out of bounds", return -1);

        pos += isl_local_space_offset(constraint->ls, type);
        return isl_int_is_neg(constraint->v->el[pos]);
}

const char *isl_constraint_get_dim_name(__isl_keep isl_constraint *constraint,
        enum isl_dim_type type, unsigned pos)
{
        return constraint ?
            isl_local_space_get_dim_name(constraint->ls, type, pos) : NULL;
}

void isl_constraint_get_constant(struct isl_constraint *constraint, isl_int *v)
{
        if (!constraint)
                return;
        isl_int_set(*v, constraint->v->el[0]);
}

void isl_constraint_get_coefficient(struct isl_constraint *constraint,
        enum isl_dim_type type, int pos, isl_int *v)
{
        if (!constraint)
                return;

        if (pos >= isl_local_space_dim(constraint->ls, type))
                isl_die(constraint->v->ctx, isl_error_invalid,
                        "position out of bounds", return);

        pos += isl_local_space_offset(constraint->ls, type);
        isl_int_set(*v, constraint->v->el[pos]);
}

__isl_give isl_aff *isl_constraint_get_div(__isl_keep isl_constraint *constraint,
        int pos)
{
        if (!constraint)
                return NULL;

        return isl_local_space_get_div(constraint->ls, pos);
}

__isl_give isl_constraint *isl_constraint_set_constant(
        __isl_take isl_constraint *constraint, isl_int v)
{
        constraint = isl_constraint_cow(constraint);
        if (!constraint)
                return NULL;

        constraint->v = isl_vec_cow(constraint->v);
        if (!constraint->v)
                return isl_constraint_free(constraint);

        isl_int_set(constraint->v->el[0], v);
        return constraint;
}

__isl_give isl_constraint *isl_constraint_set_constant_si(
        __isl_take isl_constraint *constraint, int v)
{
        constraint = isl_constraint_cow(constraint);
        if (!constraint)
                return NULL;

        constraint->v = isl_vec_cow(constraint->v);
        if (!constraint->v)
                return isl_constraint_free(constraint);

        isl_int_set_si(constraint->v->el[0], v);
        return constraint;
}

__isl_give isl_constraint *isl_constraint_set_coefficient(
        __isl_take isl_constraint *constraint,
        enum isl_dim_type type, int pos, isl_int v)
{
        constraint = isl_constraint_cow(constraint);
        if (!constraint)
                return NULL;

        if (pos >= isl_local_space_dim(constraint->ls, type))
                isl_die(constraint->v->ctx, isl_error_invalid,
                        "position out of bounds",
                        return isl_constraint_free(constraint));

        constraint = isl_constraint_cow(constraint);
        if (!constraint)
                return NULL;

        constraint->v = isl_vec_cow(constraint->v);
        if (!constraint->v)
                return isl_constraint_free(constraint);

        pos += isl_local_space_offset(constraint->ls, type);
        isl_int_set(constraint->v->el[pos], v);

        return constraint;
}

__isl_give isl_constraint *isl_constraint_set_coefficient_si(
        __isl_take isl_constraint *constraint,
        enum isl_dim_type type, int pos, int v)
{
        constraint = isl_constraint_cow(constraint);
        if (!constraint)
                return NULL;

        if (pos >= isl_local_space_dim(constraint->ls, type))
                isl_die(constraint->v->ctx, isl_error_invalid,
                        "position out of bounds",
                        return isl_constraint_free(constraint));

        constraint = isl_constraint_cow(constraint);
        if (!constraint)
                return NULL;

        constraint->v = isl_vec_cow(constraint->v);
        if (!constraint->v)
                return isl_constraint_free(constraint);

        pos += isl_local_space_offset(constraint->ls, type);
        isl_int_set_si(constraint->v->el[pos], v);

        return constraint;
}

/* Drop any constraint from "bset" that is identical to "constraint".
 * In particular, this means that the local spaces of "bset" and
 * "constraint" need to be the same.
 *
 * Since the given constraint may actually be a pointer into the bset,
 * we have to be careful not to reorder the constraints as the user
 * may be holding on to other constraints from the same bset.
 * This should be cleaned up when the internal representation of
 * isl_constraint is changed to use isl_aff.
 */
__isl_give isl_basic_set *isl_basic_set_drop_constraint(
        __isl_take isl_basic_set *bset, __isl_take isl_constraint *constraint)
{
        int i;
        unsigned n;
        isl_int **row;
        unsigned total;
        isl_local_space *ls1;
        int equal;

        if (!bset || !constraint)
                goto error;

        ls1 = isl_basic_set_get_local_space(bset);
        equal = isl_local_space_is_equal(ls1, constraint->ls);
        isl_local_space_free(ls1);
        if (equal < 0)
                goto error;
        if (!equal) {
                isl_constraint_free(constraint);
                return bset;
        }

        if (isl_constraint_is_equality(constraint)) {
                n = bset->n_eq;
                row = bset->eq;
        } else {
                n = bset->n_ineq;
                row = bset->ineq;
        }

        total = isl_constraint_dim(constraint, isl_dim_all);
        for (i = 0; i < n; ++i)
                if (isl_seq_eq(row[i], constraint->v->el, 1 + total))
                        isl_seq_clr(row[i], 1 + total);
                        
        isl_constraint_free(constraint);
        return bset;
error:
        isl_constraint_free(constraint);
        isl_basic_set_free(bset);
        return NULL;
}

struct isl_constraint *isl_constraint_negate(struct isl_constraint *constraint)
{
        isl_ctx *ctx;

        constraint = isl_constraint_cow(constraint);
        if (!constraint)
                return NULL;

        ctx = isl_constraint_get_ctx(constraint);
        if (isl_constraint_is_equality(constraint))
                isl_die(ctx, isl_error_invalid, "cannot negate equality",
                        return isl_constraint_free(constraint));
        constraint->v = isl_vec_neg(constraint->v);
        constraint->v = isl_vec_cow(constraint->v);
        if (!constraint->v)
                return isl_constraint_free(constraint);
        isl_int_sub_ui(constraint->v->el[0], constraint->v->el[0], 1);
        return constraint;
}

int isl_constraint_is_equality(struct isl_constraint *constraint)
{
        if (!constraint)
                return -1;
        return constraint->eq;
}

int isl_constraint_is_div_constraint(__isl_keep isl_constraint *constraint)
{
        int i;
        int n_div;

        if (!constraint)
                return -1;
        if (isl_constraint_is_equality(constraint))
                return 0;
        n_div = isl_constraint_dim(constraint, isl_dim_div);
        for (i = 0; i < n_div; ++i) {
                if (isl_local_space_is_div_constraint(constraint->ls,
                                                        constraint->v->el, i))
                        return 1;
        }

        return 0;
}

/* We manually set ISL_BASIC_SET_FINAL instead of calling
 * isl_basic_map_finalize because we want to keep the position
 * of the divs and we therefore do not want to throw away redundant divs.
 * This is arguably a bit fragile.
 */
__isl_give isl_basic_map *isl_basic_map_from_constraint(
        __isl_take isl_constraint *constraint)
{
        int k;
        isl_local_space *ls;
        struct isl_basic_map *bmap;
        isl_int *c;
        unsigned total;

        if (!constraint)
                return NULL;

        ls = isl_local_space_copy(constraint->ls);
        bmap = isl_basic_map_from_local_space(ls);
        bmap = isl_basic_map_extend_constraints(bmap, 1, 1);
        if (isl_constraint_is_equality(constraint)) {
                k = isl_basic_map_alloc_equality(bmap);
                if (k < 0)
                        goto error;
                c = bmap->eq[k];
        }
        else {
                k = isl_basic_map_alloc_inequality(bmap);
                if (k < 0)
                        goto error;
                c = bmap->ineq[k];
        }
        total = isl_basic_map_total_dim(bmap);
        isl_seq_cpy(c, constraint->v->el, 1 + total);
        isl_constraint_free(constraint);
        if (bmap)
                ISL_F_SET(bmap, ISL_BASIC_SET_FINAL);
        return bmap;
error:
        isl_constraint_free(constraint);
        isl_basic_map_free(bmap);
        return NULL;
}

struct isl_basic_set *isl_basic_set_from_constraint(
        struct isl_constraint *constraint)
{
        if (!constraint)
                return NULL;

        if (isl_constraint_dim(constraint, isl_dim_in) != 0)
                isl_die(isl_constraint_get_ctx(constraint), isl_error_invalid,
                        "not a set constraint",
                        return isl_constraint_free(constraint));
        return (isl_basic_set *)isl_basic_map_from_constraint(constraint);
}

int isl_basic_map_has_defining_equality(
        __isl_keep isl_basic_map *bmap, enum isl_dim_type type, int pos,
        __isl_give isl_constraint **c)
{
        int i;
        unsigned offset;
        unsigned total;

        if (!bmap)
                return -1;
        offset = basic_map_offset(bmap, type);
        total = isl_basic_map_total_dim(bmap);
        isl_assert(bmap->ctx, pos < isl_basic_map_dim(bmap, type), return -1);
        for (i = 0; i < bmap->n_eq; ++i)
                if (!isl_int_is_zero(bmap->eq[i][offset + pos]) &&
                    isl_seq_first_non_zero(bmap->eq[i]+offset+pos+1,
                                           1+total-offset-pos-1) == -1) {
                        *c = isl_basic_map_constraint(isl_basic_map_copy(bmap),
                                                                &bmap->eq[i]);
                        return 1;
                }
        return 0;
}

int isl_basic_set_has_defining_equality(
        __isl_keep isl_basic_set *bset, enum isl_dim_type type, int pos,
        __isl_give isl_constraint **c)
{
        return isl_basic_map_has_defining_equality((isl_basic_map *)bset,
                                                    type, pos, c);
}

int isl_basic_set_has_defining_inequalities(
        struct isl_basic_set *bset, enum isl_dim_type type, int pos,
        struct isl_constraint **lower,
        struct isl_constraint **upper)
{
        int i, j;
        unsigned offset;
        unsigned total;
        isl_int m;
        isl_int **lower_line, **upper_line;

        if (!bset)
                return -1;
        offset = basic_set_offset(bset, type);
        total = isl_basic_set_total_dim(bset);
        isl_assert(bset->ctx, pos < isl_basic_set_dim(bset, type), return -1);
        isl_int_init(m);
        for (i = 0; i < bset->n_ineq; ++i) {
                if (isl_int_is_zero(bset->ineq[i][offset + pos]))
                        continue;
                if (isl_int_is_one(bset->ineq[i][offset + pos]))
                        continue;
                if (isl_int_is_negone(bset->ineq[i][offset + pos]))
                        continue;
                if (isl_seq_first_non_zero(bset->ineq[i]+offset+pos+1,
                                                1+total-offset-pos-1) != -1)
                        continue;
                for (j = i + 1; j < bset->n_ineq; ++j) {
                        if (!isl_seq_is_neg(bset->ineq[i]+1, bset->ineq[j]+1,
                                            total))
                                continue;
                        isl_int_add(m, bset->ineq[i][0], bset->ineq[j][0]);
                        if (isl_int_abs_ge(m, bset->ineq[i][offset+pos]))
                                continue;

                        if (isl_int_is_pos(bset->ineq[i][offset+pos])) {
                                lower_line = &bset->ineq[i];
                                upper_line = &bset->ineq[j];
                        } else {
                                lower_line = &bset->ineq[j];
                                upper_line = &bset->ineq[i];
                        }
                        *lower = isl_basic_set_constraint(
                                        isl_basic_set_copy(bset), lower_line);
                        *upper = isl_basic_set_constraint(
                                        isl_basic_set_copy(bset), upper_line);
                        isl_int_clear(m);
                        return 1;
                }
        }
        *lower = NULL;
        *upper = NULL;
        isl_int_clear(m);
        return 0;
}

/* Given two constraints "a" and "b" on the variable at position "abs_pos"
 * (in "a" and "b"), add a constraint to "bset" that ensures that the
 * bound implied by "a" is (strictly) larger than the bound implied by "b".
 *
 * If both constraints imply lower bounds, then this means that "a" is
 * active in the result.
 * If both constraints imply upper bounds, then this means that "b" is
 * active in the result.
 */
static __isl_give isl_basic_set *add_larger_bound_constraint(
        __isl_take isl_basic_set *bset, isl_int *a, isl_int *b,
        unsigned abs_pos, int strict)
{
        int k;
        isl_int t;
        unsigned total;

        k = isl_basic_set_alloc_inequality(bset);
        if (k < 0)
                goto error;

        total = isl_basic_set_dim(bset, isl_dim_all);

        isl_int_init(t);
        isl_int_neg(t, b[1 + abs_pos]);

        isl_seq_combine(bset->ineq[k], t, a, a[1 + abs_pos], b, 1 + abs_pos);
        isl_seq_combine(bset->ineq[k] + 1 + abs_pos,
                t, a + 1 + abs_pos + 1, a[1 + abs_pos], b + 1 + abs_pos + 1,
                total - abs_pos);

        if (strict)
                isl_int_sub_ui(bset->ineq[k][0], bset->ineq[k][0], 1);

        isl_int_clear(t);

        return bset;
error:
        isl_basic_set_free(bset);
        return NULL;
}

/* Add constraints to "context" that ensure that "u" is the smallest
 * (and therefore active) upper bound on "abs_pos" in "bset" and return
 * the resulting basic set.
 */
static __isl_give isl_basic_set *set_smallest_upper_bound(
        __isl_keep isl_basic_set *context,
        __isl_keep isl_basic_set *bset, unsigned abs_pos, int n_upper, int u)
{
        int j;

        context = isl_basic_set_copy(context);
        context = isl_basic_set_cow(context);

        context = isl_basic_set_extend_constraints(context, 0, n_upper - 1);

        for (j = 0; j < bset->n_ineq; ++j) {
                if (j == u)
                        continue;
                if (!isl_int_is_neg(bset->ineq[j][1 + abs_pos]))
                        continue;
                context = add_larger_bound_constraint(context,
                        bset->ineq[j], bset->ineq[u], abs_pos, j > u);
        }

        context = isl_basic_set_simplify(context);
        context = isl_basic_set_finalize(context);

        return context;
}

/* Add constraints to "context" that ensure that "u" is the largest
 * (and therefore active) upper bound on "abs_pos" in "bset" and return
 * the resulting basic set.
 */
static __isl_give isl_basic_set *set_largest_lower_bound(
        __isl_keep isl_basic_set *context,
        __isl_keep isl_basic_set *bset, unsigned abs_pos, int n_lower, int l)
{
        int j;

        context = isl_basic_set_copy(context);
        context = isl_basic_set_cow(context);

        context = isl_basic_set_extend_constraints(context, 0, n_lower - 1);

        for (j = 0; j < bset->n_ineq; ++j) {
                if (j == l)
                        continue;
                if (!isl_int_is_pos(bset->ineq[j][1 + abs_pos]))
                        continue;
                context = add_larger_bound_constraint(context,
                        bset->ineq[l], bset->ineq[j], abs_pos, j > l);
        }

        context = isl_basic_set_simplify(context);
        context = isl_basic_set_finalize(context);

        return context;
}

static int foreach_upper_bound(__isl_keep isl_basic_set *bset,
        enum isl_dim_type type, unsigned abs_pos,
        __isl_take isl_basic_set *context, int n_upper,
        int (*fn)(__isl_take isl_constraint *lower,
                  __isl_take isl_constraint *upper,
                  __isl_take isl_basic_set *bset, void *user), void *user)
{
        isl_basic_set *context_i;
        isl_constraint *upper = NULL;
        int i;

        for (i = 0; i < bset->n_ineq; ++i) {
                if (isl_int_is_zero(bset->ineq[i][1 + abs_pos]))
                        continue;

                context_i = set_smallest_upper_bound(context, bset,
                                                        abs_pos, n_upper, i);
                if (isl_basic_set_is_empty(context_i)) {
                        isl_basic_set_free(context_i);
                        continue;
                }
                upper = isl_basic_set_constraint(isl_basic_set_copy(bset),
                                                &bset->ineq[i]);
                if (!upper || !context_i)
                        goto error;
                if (fn(NULL, upper, context_i, user) < 0)
                        break;
        }

        isl_basic_set_free(context);

        if (i < bset->n_ineq)
                return -1;

        return 0;
error:
        isl_constraint_free(upper);
        isl_basic_set_free(context_i);
        isl_basic_set_free(context);
        return -1;
}

static int foreach_lower_bound(__isl_keep isl_basic_set *bset,
        enum isl_dim_type type, unsigned abs_pos,
        __isl_take isl_basic_set *context, int n_lower,
        int (*fn)(__isl_take isl_constraint *lower,
                  __isl_take isl_constraint *upper,
                  __isl_take isl_basic_set *bset, void *user), void *user)
{
        isl_basic_set *context_i;
        isl_constraint *lower = NULL;
        int i;

        for (i = 0; i < bset->n_ineq; ++i) {
                if (isl_int_is_zero(bset->ineq[i][1 + abs_pos]))
                        continue;

                context_i = set_largest_lower_bound(context, bset,
                                                        abs_pos, n_lower, i);
                if (isl_basic_set_is_empty(context_i)) {
                        isl_basic_set_free(context_i);
                        continue;
                }
                lower = isl_basic_set_constraint(isl_basic_set_copy(bset),
                                                &bset->ineq[i]);
                if (!lower || !context_i)
                        goto error;
                if (fn(lower, NULL, context_i, user) < 0)
                        break;
        }

        isl_basic_set_free(context);

        if (i < bset->n_ineq)
                return -1;

        return 0;
error:
        isl_constraint_free(lower);
        isl_basic_set_free(context_i);
        isl_basic_set_free(context);
        return -1;
}

static int foreach_bound_pair(__isl_keep isl_basic_set *bset,
        enum isl_dim_type type, unsigned abs_pos,
        __isl_take isl_basic_set *context, int n_lower, int n_upper,
        int (*fn)(__isl_take isl_constraint *lower,
                  __isl_take isl_constraint *upper,
                  __isl_take isl_basic_set *bset, void *user), void *user)
{
        isl_basic_set *context_i, *context_j;
        isl_constraint *lower = NULL;
        isl_constraint *upper = NULL;
        int i, j;

        for (i = 0; i < bset->n_ineq; ++i) {
                if (!isl_int_is_pos(bset->ineq[i][1 + abs_pos]))
                        continue;

                context_i = set_largest_lower_bound(context, bset,
                                                        abs_pos, n_lower, i);
                if (isl_basic_set_is_empty(context_i)) {
                        isl_basic_set_free(context_i);
                        continue;
                }

                for (j = 0; j < bset->n_ineq; ++j) {
                        if (!isl_int_is_neg(bset->ineq[j][1 + abs_pos]))
                                continue;

                        context_j = set_smallest_upper_bound(context_i, bset,
                                                            abs_pos, n_upper, j);
                        context_j = isl_basic_set_extend_constraints(context_j,
                                                                        0, 1);
                        context_j = add_larger_bound_constraint(context_j,
                                bset->ineq[i], bset->ineq[j], abs_pos, 0);
                        context_j = isl_basic_set_simplify(context_j);
                        context_j = isl_basic_set_finalize(context_j);
                        if (isl_basic_set_is_empty(context_j)) {
                                isl_basic_set_free(context_j);
                                continue;
                        }
                        lower = isl_basic_set_constraint(isl_basic_set_copy(bset),
                                                        &bset->ineq[i]);
                        upper = isl_basic_set_constraint(isl_basic_set_copy(bset),
                                                        &bset->ineq[j]);
                        if (!lower || !upper || !context_j)
                                goto error;
                        if (fn(lower, upper, context_j, user) < 0)
                                break;
                }

                isl_basic_set_free(context_i);

                if (j < bset->n_ineq)
                        break;
        }

        isl_basic_set_free(context);

        if (i < bset->n_ineq)
                return -1;

        return 0;
error:
        isl_constraint_free(lower);
        isl_constraint_free(upper);
        isl_basic_set_free(context_i);
        isl_basic_set_free(context_j);
        isl_basic_set_free(context);
        return -1;
}

/* For each pair of lower and upper bounds on the variable "pos"
 * of type "type", call "fn" with these lower and upper bounds and the
 * set of constraints on the remaining variables where these bounds
 * are active, i.e., (stricly) larger/smaller than the other lower/upper bounds.
 *
 * If the designated variable is equal to an affine combination of the
 * other variables then fn is called with both lower and upper
 * set to the corresponding equality.
 *
 * If there is no lower (or upper) bound, then NULL is passed
 * as the corresponding bound.
 *
 * We first check if the variable is involved in any equality.
 * If not, we count the number of lower and upper bounds and
 * act accordingly.
 */
int isl_basic_set_foreach_bound_pair(__isl_keep isl_basic_set *bset,
        enum isl_dim_type type, unsigned pos,
        int (*fn)(__isl_take isl_constraint *lower,
                  __isl_take isl_constraint *upper,
                  __isl_take isl_basic_set *bset, void *user), void *user)
{
        int i;
        isl_constraint *lower = NULL;
        isl_constraint *upper = NULL;
        isl_basic_set *context = NULL;
        unsigned abs_pos;
        int n_lower, n_upper;

        if (!bset)
                return -1;
        isl_assert(bset->ctx, pos < isl_basic_set_dim(bset, type), return -1);
        isl_assert(bset->ctx, type == isl_dim_param || type == isl_dim_set,
                return -1);

        abs_pos = pos;
        if (type == isl_dim_set)
                abs_pos += isl_basic_set_dim(bset, isl_dim_param);

        for (i = 0; i < bset->n_eq; ++i) {
                if (isl_int_is_zero(bset->eq[i][1 + abs_pos]))
                        continue;

                lower = isl_basic_set_constraint(isl_basic_set_copy(bset),
                                                &bset->eq[i]);
                upper = isl_constraint_copy(lower);
                context = isl_basic_set_remove_dims(isl_basic_set_copy(bset),
                                        type, pos, 1);
                if (!lower || !upper || !context)
                        goto error;
                return fn(lower, upper, context, user);
        }

        n_lower = 0;
        n_upper = 0;
        for (i = 0; i < bset->n_ineq; ++i) {
                if (isl_int_is_pos(bset->ineq[i][1 + abs_pos]))
                        n_lower++;
                else if (isl_int_is_neg(bset->ineq[i][1 + abs_pos]))
                        n_upper++;
        }

        context = isl_basic_set_copy(bset);
        context = isl_basic_set_cow(context);
        if (!context)
                goto error;
        for (i = context->n_ineq - 1; i >= 0; --i)
                if (!isl_int_is_zero(context->ineq[i][1 + abs_pos]))
                        isl_basic_set_drop_inequality(context, i);

        context = isl_basic_set_drop(context, type, pos, 1);
        if (!n_lower && !n_upper)
                return fn(NULL, NULL, context, user);
        if (!n_lower)
                return foreach_upper_bound(bset, type, abs_pos, context, n_upper,
                                                fn, user);
        if (!n_upper)
                return foreach_lower_bound(bset, type, abs_pos, context, n_lower,
                                                fn, user);
        return foreach_bound_pair(bset, type, abs_pos, context, n_lower, n_upper,
                                        fn, user);
error:
        isl_constraint_free(lower);
        isl_constraint_free(upper);
        isl_basic_set_free(context);
        return -1;
}

__isl_give isl_aff *isl_constraint_get_bound(
        __isl_keep isl_constraint *constraint, enum isl_dim_type type, int pos)
{
        isl_aff *aff;
        isl_ctx *ctx;

        if (!constraint)
                return NULL;
        ctx = isl_constraint_get_ctx(constraint);
        if (pos >= isl_constraint_dim(constraint, type))
                isl_die(ctx, isl_error_invalid,
                        "index out of bounds", return NULL);
        if (isl_constraint_dim(constraint, isl_dim_in) != 0)
                isl_die(ctx, isl_error_invalid,
                        "not a set constraint", return NULL);

        pos += offset(constraint, type);
        if (isl_int_is_zero(constraint->v->el[pos]))
                isl_die(ctx, isl_error_invalid,
                        "constraint does not define a bound on given dimension",
                        return NULL);

        aff = isl_aff_alloc(isl_local_space_copy(constraint->ls));
        if (!aff)
                return NULL;

        if (isl_int_is_neg(constraint->v->el[pos]))
                isl_seq_cpy(aff->v->el + 1, constraint->v->el, aff->v->size - 1);
        else
                isl_seq_neg(aff->v->el + 1, constraint->v->el, aff->v->size - 1);
        isl_int_set_si(aff->v->el[1 + pos], 0);
        isl_int_abs(aff->v->el[0], constraint->v->el[pos]);

        return aff;
}

/* For an inequality constraint
 *
 *      f >= 0
 *
 * or an equality constraint
 *
 *      f = 0
 *
 * return the affine expression f.
 */
__isl_give isl_aff *isl_constraint_get_aff(
        __isl_keep isl_constraint *constraint)
{
        isl_aff *aff;

        if (!constraint)
                return NULL;

        aff = isl_aff_alloc(isl_local_space_copy(constraint->ls));
        if (!aff)
                return NULL;

        isl_seq_cpy(aff->v->el + 1, constraint->v->el, aff->v->size - 1);
        isl_int_set_si(aff->v->el[0], 1);

        return aff;
}

/* Construct an equality constraint equating the given affine expression
 * to zero.
 */
__isl_give isl_constraint *isl_equality_from_aff(__isl_take isl_aff *aff)
{
        int k;
        isl_local_space *ls;
        isl_basic_set *bset;

        if (!aff)
                return NULL;

        ls = isl_aff_get_domain_local_space(aff);
        bset = isl_basic_set_from_local_space(ls);
        bset = isl_basic_set_extend_constraints(bset, 1, 0);
        k = isl_basic_set_alloc_equality(bset);
        if (k < 0)
                goto error;

        isl_seq_cpy(bset->eq[k], aff->v->el + 1, aff->v->size - 1);
        isl_aff_free(aff);

        return isl_basic_set_constraint(bset, &bset->eq[k]);
error:
        isl_aff_free(aff);
        isl_basic_set_free(bset);
        return NULL;
}

/* Construct an inequality constraint enforcing the given affine expression
 * to be non-negative.
 */
__isl_give isl_constraint *isl_inequality_from_aff(__isl_take isl_aff *aff)
{
        int k;
        isl_local_space *ls;
        isl_basic_set *bset;

        if (!aff)
                return NULL;

        ls = isl_aff_get_domain_local_space(aff);
        bset = isl_basic_set_from_local_space(ls);
        bset = isl_basic_set_extend_constraints(bset, 0, 1);
        k = isl_basic_set_alloc_inequality(bset);
        if (k < 0)
                goto error;

        isl_seq_cpy(bset->ineq[k], aff->v->el + 1, aff->v->size - 1);
        isl_aff_free(aff);

        return isl_basic_set_constraint(bset, &bset->ineq[k]);
error:
        isl_aff_free(aff);
        isl_basic_set_free(bset);
        return NULL;
}