return NULL;
}
-/* Drop n input dimensions starting at first.
+/* Move "n" divs starting at "first" to the end of the list of divs.
+ */
+static struct isl_basic_map *move_divs_last(struct isl_basic_map *bmap,
+ unsigned first, unsigned n)
+{
+ isl_int **div;
+ int i;
+
+ if (first + n == bmap->n_div)
+ return bmap;
+
+ div = isl_alloc_array(bmap->ctx, isl_int *, n);
+ if (!div)
+ goto error;
+ for (i = 0; i < n; ++i)
+ div[i] = bmap->div[first + i];
+ for (i = 0; i < bmap->n_div - first - n; ++i)
+ bmap->div[first + i] = bmap->div[first + n + i];
+ for (i = 0; i < n; ++i)
+ bmap->div[bmap->n_div - n + i] = div[i];
+ free(div);
+ return bmap;
+error:
+ isl_basic_map_free(bmap);
+ return NULL;
+}
+
+/* Drop "n" dimensions of type "type" starting at "first".
*
* In principle, this frees up some extra variables as the number
* of columns remains constant, but we would have to extend
for (i = 0; i < bmap->n_div; ++i)
constraint_drop_vars(bmap->div[i]+1+offset, n, left);
- bmap->dim = isl_dim_drop(bmap->dim, type, first, n);
+ if (type == isl_dim_div) {
+ bmap = move_divs_last(bmap, first, n);
+ if (!bmap)
+ goto error;
+ isl_basic_map_free_div(bmap, n);
+ } else
+ bmap->dim = isl_dim_drop(bmap->dim, type, first, n);
if (!bmap->dim)
goto error;
return bmap;
}
+static int n_pure_div_eq(struct isl_basic_map *bmap)
+{
+ int i, j;
+ unsigned total;
+
+ total = isl_dim_total(bmap->dim);
+ for (i = 0, j = bmap->n_div-1; i < bmap->n_eq; ++i) {
+ while (j >= 0 && isl_int_is_zero(bmap->eq[i][1 + total + j]))
+ --j;
+ if (j < 0)
+ break;
+ if (isl_seq_first_non_zero(bmap->eq[i] + 1 + total, j) != -1)
+ return 0;
+ }
+ return i;
+}
+
/* Normalize divs that appear in equalities.
*
* In particular, we assume that bmap contains some equalities
return bmap;
total = isl_dim_total(bmap->dim);
- for (i = 0, j = bmap->n_div-1; i < bmap->n_eq; ++i) {
- while (j >= 0 && isl_int_is_zero(bmap->eq[i][1 + total + j]))
- --j;
- if (j < 0)
- break;
- if (isl_seq_first_non_zero(bmap->eq[i] + 1 + total, j) != -1)
- goto done;
- }
- div_eq = i;
+ div_eq = n_pure_div_eq(bmap);
if (div_eq == 0)
return bmap;
isl_mat_free(bmap->ctx, C2);
isl_mat_free(bmap->ctx, T);
- *progress = 1;
+ if (progress)
+ *progress = 1;
done:
ISL_F_SET(bmap, ISL_BASIC_MAP_NORMALIZED_DIVS);
return bmap;
}
+static struct isl_basic_map *set_div_from_lower_bound(
+ struct isl_basic_map *bmap, int div, int ineq)
+{
+ unsigned total = 1 + isl_dim_total(bmap->dim);
+
+ isl_seq_neg(bmap->div[div] + 1, bmap->ineq[ineq], total + bmap->n_div);
+ isl_int_set(bmap->div[div][0], bmap->ineq[ineq][total + div]);
+ isl_int_add(bmap->div[div][1], bmap->div[div][1], bmap->div[div][0]);
+ isl_int_sub_ui(bmap->div[div][1], bmap->div[div][1], 1);
+ isl_int_set_si(bmap->div[div][1 + total + div], 0);
+
+ return bmap;
+}
+
+/* Check whether it is ok to define a div based on an inequality.
+ * To avoid the introduction of circular definitions of divs, we
+ * do not allow such a definition if the resulting expression would refer to
+ * any other undefined divs or if any known div is defined in
+ * terms of the unknown div.
+ */
+static int ok_to_set_div_from_bound(struct isl_basic_map *bmap,
+ int div, int ineq)
+{
+ int j;
+ unsigned total = 1 + isl_dim_total(bmap->dim);
+
+ /* Not defined in terms of unknown divs */
+ for (j = 0; j < bmap->n_div; ++j) {
+ if (div == j)
+ continue;
+ if (isl_int_is_zero(bmap->ineq[ineq][total + j]))
+ continue;
+ if (isl_int_is_zero(bmap->div[j][0]))
+ return 0;
+ }
+
+ /* No other div defined in terms of this one => avoid loops */
+ for (j = 0; j < bmap->n_div; ++j) {
+ if (div == j)
+ continue;
+ if (isl_int_is_zero(bmap->div[j][0]))
+ continue;
+ if (!isl_int_is_zero(bmap->div[j][1 + total + div]))
+ return 0;
+ }
+
+ return 1;
+}
+
+/* Given two constraints "k" and "l" that are opposite to each other,
+ * except for the constant term, check if we can use them
+ * to obtain an expression for one of the hitherto unknown divs.
+ * "sum" is the sum of the constant terms of the constraints.
+ * If this sum is strictly smaller than the coefficient of one
+ * of the divs, then this pair can be used define the div.
+ * To avoid the introduction of circular definitions of divs, we
+ * do not use the pair if the resulting expression would refer to
+ * any other undefined divs or if any known div is defined in
+ * terms of the unknown div.
+ */
+static struct isl_basic_map *check_for_div_constraints(
+ struct isl_basic_map *bmap, int k, int l, isl_int sum, int *progress)
+{
+ int i, j;
+ unsigned total = 1 + isl_dim_total(bmap->dim);
+
+ for (i = 0; i < bmap->n_div; ++i) {
+ if (!isl_int_is_zero(bmap->div[i][0]))
+ continue;
+ if (isl_int_is_zero(bmap->ineq[k][total + i]))
+ continue;
+ if (isl_int_abs_ge(sum, bmap->ineq[k][total + i]))
+ continue;
+ if (!ok_to_set_div_from_bound(bmap, i, k))
+ break;
+ if (isl_int_is_pos(bmap->ineq[k][total + i]))
+ bmap = set_div_from_lower_bound(bmap, i, k);
+ else
+ bmap = set_div_from_lower_bound(bmap, i, l);
+ if (progress)
+ *progress = 1;
+ break;
+ }
+ return bmap;
+}
+
static struct isl_basic_map *remove_duplicate_constraints(
struct isl_basic_map *bmap, int *progress)
{
continue;
l = index[h] - &bmap->ineq[0];
isl_int_add(sum, bmap->ineq[k][0], bmap->ineq[l][0]);
- if (isl_int_is_pos(sum))
+ if (isl_int_is_pos(sum)) {
+ bmap = check_for_div_constraints(bmap, k, l, sum,
+ progress);
continue;
+ }
if (isl_int_is_zero(sum)) {
/* We need to break out of the loop after these
* changes since the contents of the hash
while (progress) {
progress = 0;
bmap = isl_basic_map_normalize_constraints(bmap);
+ bmap = remove_duplicate_divs(bmap, &progress);
bmap = eliminate_divs_eq(bmap, &progress);
bmap = eliminate_divs_ineq(bmap, &progress);
bmap = isl_basic_map_gauss(bmap, &progress);
/* requires equalities in normal form */
bmap = normalize_divs(bmap, &progress);
- bmap = remove_duplicate_divs(bmap, &progress);
bmap = remove_duplicate_constraints(bmap, &progress);
}
return bmap;
if (ISL_F_ISSET(bset, ISL_BASIC_SET_RATIONAL))
return bset;
+ if (!bset->n_ineq)
+ return bset;
+
bset = isl_basic_set_cow(bset);
if (!bset)
return NULL;
isl_basic_set_copy(context));
if (!bset)
goto error;
+ if (isl_basic_set_fast_is_empty(bset))
+ goto done;
+ if (!bset->n_ineq)
+ goto done;
if (bset->n_eq > 0) {
struct isl_basic_set *affine_hull;
return NULL;
}
+/* Normalize the divs in "bmap" in the context of the equalities in "context".
+ * We simply add the equalities in context to bmap and then do a regular
+ * div normalizations. Better results can be obtained by normalizing
+ * only the divs in bmap than do not also appear in context.
+ * We need to be careful to reduce the divs using the equalities
+ * so that later calls to isl_basic_map_overlying_set wouldn't introduce
+ * spurious constraints.
+ */
+static struct isl_basic_map *normalize_divs_in_context(
+ struct isl_basic_map *bmap, struct isl_basic_map *context)
+{
+ int i;
+ unsigned total_context;
+ int div_eq;
+
+ div_eq = n_pure_div_eq(bmap);
+ if (div_eq == 0)
+ return bmap;
+
+ if (context->n_div > 0)
+ bmap = isl_basic_map_align_divs(bmap, context);
+
+ total_context = isl_basic_map_total_dim(context);
+ bmap = isl_basic_map_extend_constraints(bmap, context->n_eq, 0);
+ for (i = 0; i < context->n_eq; ++i) {
+ int k;
+ k = isl_basic_map_alloc_equality(bmap);
+ isl_seq_cpy(bmap->eq[k], context->eq[i], 1 + total_context);
+ isl_seq_clr(bmap->eq[k] + 1 + total_context,
+ isl_basic_map_total_dim(bmap) - total_context);
+ }
+ bmap = isl_basic_map_gauss(bmap, NULL);
+ bmap = normalize_divs(bmap, NULL);
+ bmap = isl_basic_map_gauss(bmap, NULL);
+ return bmap;
+}
+
struct isl_basic_map *isl_basic_map_gist(struct isl_basic_map *bmap,
struct isl_basic_map *context)
{
bmap = isl_basic_map_convex_hull(bmap);
context = isl_basic_map_convex_hull(context);
+ if (context->n_eq)
+ bmap = normalize_divs_in_context(bmap, context);
+
context = isl_basic_map_align_divs(context, bmap);
bmap = isl_basic_map_align_divs(bmap, context);
isl_seq_first_non_zero(v->block.data + 1, total) == -1)
goto disjoint;
}
- isl_vec_free(bmap1->ctx, v);
+ isl_vec_free(v);
free(elim);
return 0;
disjoint:
- isl_vec_free(bmap1->ctx, v);
+ isl_vec_free(v);
free(elim);
return 1;
error:
- isl_vec_free(bmap1->ctx, v);
+ isl_vec_free(v);
free(elim);
return -1;
}
return isl_map_fast_is_disjoint((struct isl_map *)set1,
(struct isl_map *)set2);
}
+
+/* Check if we can combine a given div with lower bound l and upper
+ * bound u with some other div and if so return that other div.
+ * Otherwise return -1.
+ *
+ * We first check that
+ * - the bounds are opposites of each other (expect for the constant
+ * term
+ * - the bounds do not reference any other div
+ * - no div is defined in terms of this div
+ *
+ * Let m be the size of the range allowed on the div by the bounds.
+ * That is, the bounds are of the form
+ *
+ * e <= a <= e + m - 1
+ *
+ * with e some expression in the other variables.
+ * We look for another div b such that no third div is defined in terms
+ * of this second div b and such that in any constraint that contains
+ * a (except for the given lower and upper bound), also contains b
+ * with a coefficient that is m times that of b.
+ * That is, all constraints (execpt for the lower and upper bound)
+ * are of the form
+ *
+ * e + f (a + m b) >= 0
+ *
+ * If so, we return b so that "a + m b" can be replaced by
+ * a single div "c = a + m b".
+ */
+static int div_find_coalesce(struct isl_basic_map *bmap, int *pairs,
+ unsigned div, unsigned l, unsigned u)
+{
+ int i, j;
+ unsigned dim;
+ int coalesce = -1;
+
+ if (bmap->n_div <= 1)
+ return -1;
+ dim = isl_dim_total(bmap->dim);
+ if (isl_seq_first_non_zero(bmap->ineq[l] + 1 + dim, div) != -1)
+ return -1;
+ if (isl_seq_first_non_zero(bmap->ineq[l] + 1 + dim + div + 1,
+ bmap->n_div - div - 1) != -1)
+ return -1;
+ if (!isl_seq_is_neg(bmap->ineq[l] + 1, bmap->ineq[u] + 1,
+ dim + bmap->n_div))
+ return -1;
+
+ for (i = 0; i < bmap->n_div; ++i) {
+ if (isl_int_is_zero(bmap->div[i][0]))
+ continue;
+ if (!isl_int_is_zero(bmap->div[i][1 + 1 + dim + div]))
+ return -1;
+ }
+
+ isl_int_add(bmap->ineq[l][0], bmap->ineq[l][0], bmap->ineq[u][0]);
+ isl_int_add_ui(bmap->ineq[l][0], bmap->ineq[l][0], 1);
+ for (i = 0; i < bmap->n_div; ++i) {
+ if (i == div)
+ continue;
+ if (!pairs[i])
+ continue;
+ for (j = 0; j < bmap->n_div; ++j) {
+ if (isl_int_is_zero(bmap->div[j][0]))
+ continue;
+ if (!isl_int_is_zero(bmap->div[j][1 + 1 + dim + i]))
+ break;
+ }
+ if (j < bmap->n_div)
+ continue;
+ for (j = 0; j < bmap->n_ineq; ++j) {
+ int valid;
+ if (j == l || j == u)
+ continue;
+ if (isl_int_is_zero(bmap->ineq[j][1 + dim + div]))
+ continue;
+ if (isl_int_is_zero(bmap->ineq[j][1 + dim + i]))
+ break;
+ isl_int_mul(bmap->ineq[j][1 + dim + div],
+ bmap->ineq[j][1 + dim + div],
+ bmap->ineq[l][0]);
+ valid = isl_int_eq(bmap->ineq[j][1 + dim + div],
+ bmap->ineq[j][1 + dim + i]);
+ isl_int_divexact(bmap->ineq[j][1 + dim + div],
+ bmap->ineq[j][1 + dim + div],
+ bmap->ineq[l][0]);
+ if (!valid)
+ break;
+ }
+ if (j < bmap->n_ineq)
+ continue;
+ coalesce = i;
+ break;
+ }
+ isl_int_sub_ui(bmap->ineq[l][0], bmap->ineq[l][0], 1);
+ isl_int_sub(bmap->ineq[l][0], bmap->ineq[l][0], bmap->ineq[u][0]);
+ return coalesce;
+}
+
+/* Given a lower and an upper bound on div i, construct an inequality
+ * that when nonnegative ensures that this pair of bounds always allows
+ * for an integer value of the given div.
+ * The lower bound is inequality l, while the upper bound is inequality u.
+ * The constructed inequality is stored in ineq.
+ * g, fl, fu are temporary scalars.
+ *
+ * Let the upper bound be
+ *
+ * -n_u a + e_u >= 0
+ *
+ * and the lower bound
+ *
+ * n_l a + e_l >= 0
+ *
+ * Let n_u = f_u g and n_l = f_l g, with g = gcd(n_u, n_l).
+ * We have
+ *
+ * - f_u e_l <= f_u f_l g a <= f_l e_u
+ *
+ * Since all variables are integer valued, this is equivalent to
+ *
+ * - f_u e_l - (f_u - 1) <= f_u f_l g a <= f_l e_u + (f_l - 1)
+ *
+ * If this interval is at least f_u f_l g, then it contains at least
+ * one integer value for a.
+ * That is, the test constraint is
+ *
+ * f_l e_u + f_u e_l + f_l - 1 + f_u - 1 + 1 >= f_u f_l g
+ */
+static void construct_test_ineq(struct isl_basic_map *bmap, int i,
+ int l, int u, isl_int *ineq, isl_int g, isl_int fl, isl_int fu)
+{
+ unsigned dim;
+ dim = isl_dim_total(bmap->dim);
+
+ isl_int_gcd(g, bmap->ineq[l][1 + dim + i], bmap->ineq[u][1 + dim + i]);
+ isl_int_divexact(fl, bmap->ineq[l][1 + dim + i], g);
+ isl_int_divexact(fu, bmap->ineq[u][1 + dim + i], g);
+ isl_int_neg(fu, fu);
+ isl_seq_combine(ineq, fl, bmap->ineq[u], fu, bmap->ineq[l],
+ 1 + dim + bmap->n_div);
+ isl_int_add(ineq[0], ineq[0], fl);
+ isl_int_add(ineq[0], ineq[0], fu);
+ isl_int_sub_ui(ineq[0], ineq[0], 1);
+ isl_int_mul(g, g, fl);
+ isl_int_mul(g, g, fu);
+ isl_int_sub(ineq[0], ineq[0], g);
+}
+
+/* Remove more kinds of divs that are not strictly needed.
+ * In particular, if all pairs of lower and upper bounds on a div
+ * are such that they allow at least one integer value of the div,
+ * the we can eliminate the div using Fourier-Motzkin without
+ * introducing any spurious solutions.
+ */
+static struct isl_basic_map *drop_more_redundant_divs(
+ struct isl_basic_map *bmap, int *pairs, int n)
+{
+ struct isl_ctx *ctx = NULL;
+ struct isl_tab *tab = NULL;
+ struct isl_vec *vec = NULL;
+ unsigned dim;
+ int remove = -1;
+ isl_int g, fl, fu;
+
+ isl_int_init(g);
+ isl_int_init(fl);
+ isl_int_init(fu);
+
+ if (!bmap)
+ goto error;
+
+ ctx = bmap->ctx;
+
+ dim = isl_dim_total(bmap->dim);
+ vec = isl_vec_alloc(ctx, 1 + dim + bmap->n_div);
+ if (!vec)
+ goto error;
+
+ tab = isl_tab_from_basic_map(bmap);
+
+ while (n > 0) {
+ int i, l, u;
+ int best = -1;
+ enum isl_lp_result res;
+
+ for (i = 0; i < bmap->n_div; ++i) {
+ if (!pairs[i])
+ continue;
+ if (best >= 0 && pairs[best] <= pairs[i])
+ continue;
+ best = i;
+ }
+
+ i = best;
+ for (l = 0; l < bmap->n_ineq; ++l) {
+ if (!isl_int_is_pos(bmap->ineq[l][1 + dim + i]))
+ continue;
+ for (u = 0; u < bmap->n_ineq; ++u) {
+ if (!isl_int_is_neg(bmap->ineq[u][1 + dim + i]))
+ continue;
+ construct_test_ineq(bmap, i, l, u,
+ vec->el, g, fl, fu);
+ res = isl_tab_min(ctx, tab, vec->el,
+ ctx->one, &g, NULL, 0);
+ if (res == isl_lp_error)
+ goto error;
+ if (res == isl_lp_empty) {
+ bmap = isl_basic_map_set_to_empty(bmap);
+ break;
+ }
+ if (res != isl_lp_ok || isl_int_is_neg(g))
+ break;
+ }
+ if (u < bmap->n_ineq)
+ break;
+ }
+ if (l == bmap->n_ineq) {
+ remove = i;
+ break;
+ }
+ pairs[i] = 0;
+ --n;
+ }
+
+ isl_tab_free(ctx, tab);
+ isl_vec_free(vec);
+
+ isl_int_clear(g);
+ isl_int_clear(fl);
+ isl_int_clear(fu);
+
+ free(pairs);
+
+ if (remove < 0)
+ return bmap;
+
+ bmap = isl_basic_map_remove(bmap, isl_dim_div, remove, 1);
+ return isl_basic_map_drop_redundant_divs(bmap);
+error:
+ free(pairs);
+ isl_basic_map_free(bmap);
+ if (ctx) {
+ isl_tab_free(ctx, tab);
+ isl_vec_free(vec);
+ }
+ isl_int_clear(g);
+ isl_int_clear(fl);
+ isl_int_clear(fu);
+ return NULL;
+}
+
+/* Given a pair of divs div1 and div2 such that, expect for the lower bound l
+ * and the upper bound u, div1 always occurs together with div2 in the form
+ * (div1 + m div2), where m is the constant range on the variable div1
+ * allowed by l and u, replace the pair div1 and div2 by a single
+ * div that is equal to div1 + m div2.
+ *
+ * The new div will appear in the location that contains div2.
+ * We need to modify all constraints that contain
+ * div2 = (div - div1) / m
+ * (If a constraint does not contain div2, it will also not contain div1.)
+ * If the constraint also contains div1, then we know they appear
+ * as f (div1 + m div2) and we can simply replace (div1 + m div2) by div,
+ * i.e., the coefficient of div is f.
+ *
+ * Otherwise, we first need to introduce div1 into the constraint.
+ * Let the l be
+ *
+ * div1 + f >=0
+ *
+ * and u
+ *
+ * -div1 + f' >= 0
+ *
+ * A lower bound on div2
+ *
+ * n div2 + t >= 0
+ *
+ * can be replaced by
+ *
+ * (n * (m div 2 + div1) + m t + n f)/g >= 0
+ *
+ * with g = gcd(m,n).
+ * An upper bound
+ *
+ * -n div2 + t >= 0
+ *
+ * can be replaced by
+ *
+ * (-n * (m div2 + div1) + m t + n f')/g >= 0
+ *
+ * These constraint are those that we would obtain from eliminating
+ * div1 using Fourier-Motzkin.
+ *
+ * After all constraints have been modified, we drop the lower and upper
+ * bound and then drop div1.
+ */
+static struct isl_basic_map *coalesce_divs(struct isl_basic_map *bmap,
+ unsigned div1, unsigned div2, unsigned l, unsigned u)
+{
+ isl_int a;
+ isl_int b;
+ isl_int m;
+ unsigned dim, total;
+ int i;
+
+ dim = isl_dim_total(bmap->dim);
+ total = 1 + dim + bmap->n_div;
+
+ isl_int_init(a);
+ isl_int_init(b);
+ isl_int_init(m);
+ isl_int_add(m, bmap->ineq[l][0], bmap->ineq[u][0]);
+ isl_int_add_ui(m, m, 1);
+
+ for (i = 0; i < bmap->n_ineq; ++i) {
+ if (i == l || i == u)
+ continue;
+ if (isl_int_is_zero(bmap->ineq[i][1 + dim + div2]))
+ continue;
+ if (isl_int_is_zero(bmap->ineq[i][1 + dim + div1])) {
+ isl_int_gcd(b, m, bmap->ineq[i][1 + dim + div2]);
+ isl_int_divexact(a, m, b);
+ isl_int_divexact(b, bmap->ineq[i][1 + dim + div2], b);
+ if (isl_int_is_pos(b)) {
+ isl_seq_combine(bmap->ineq[i], a, bmap->ineq[i],
+ b, bmap->ineq[l], total);
+ } else {
+ isl_int_neg(b, b);
+ isl_seq_combine(bmap->ineq[i], a, bmap->ineq[i],
+ b, bmap->ineq[u], total);
+ }
+ }
+ isl_int_set(bmap->ineq[i][1 + dim + div2],
+ bmap->ineq[i][1 + dim + div1]);
+ isl_int_set_si(bmap->ineq[i][1 + dim + div1], 0);
+ }
+
+ isl_int_clear(a);
+ isl_int_clear(b);
+ isl_int_clear(m);
+ if (l > u) {
+ isl_basic_map_drop_inequality(bmap, l);
+ isl_basic_map_drop_inequality(bmap, u);
+ } else {
+ isl_basic_map_drop_inequality(bmap, u);
+ isl_basic_map_drop_inequality(bmap, l);
+ }
+ bmap = isl_basic_map_drop_div(bmap, div1);
+ return bmap;
+}
+
+/* First check if we can coalesce any pair of divs and
+ * then continue with dropping more redundant divs.
+ *
+ * We loop over all pairs of lower and upper bounds on a div
+ * with coefficient 1 and -1, respectively, check if there
+ * is any other div "c" with which we can coalesce the div
+ * and if so, perform the coalescing.
+ */
+static struct isl_basic_map *coalesce_or_drop_more_redundant_divs(
+ struct isl_basic_map *bmap, int *pairs, int n)
+{
+ int i, l, u;
+ unsigned dim;
+
+ dim = isl_dim_total(bmap->dim);
+
+ for (i = 0; i < bmap->n_div; ++i) {
+ if (!pairs[i])
+ continue;
+ for (l = 0; l < bmap->n_ineq; ++l) {
+ if (!isl_int_is_one(bmap->ineq[l][1 + dim + i]))
+ continue;
+ for (u = 0; u < bmap->n_ineq; ++u) {
+ int c;
+
+ if (!isl_int_is_negone(bmap->ineq[u][1+dim+i]))
+ continue;
+ c = div_find_coalesce(bmap, pairs, i, l, u);
+ if (c < 0)
+ continue;
+ free(pairs);
+ bmap = coalesce_divs(bmap, i, c, l, u);
+ return isl_basic_map_drop_redundant_divs(bmap);
+ }
+ }
+ }
+
+ return drop_more_redundant_divs(bmap, pairs, n);
+}
+
+/* Remove divs that are not strictly needed.
+ * In particular, if a div only occurs positively (or negatively)
+ * in constraints, then it can simply be dropped.
+ * Also, if a div occurs only occurs in two constraints and if moreover
+ * those two constraints are opposite to each other, except for the constant
+ * term and if the sum of the constant terms is such that for any value
+ * of the other values, there is always at least one integer value of the
+ * div, i.e., if one plus this sum is greater than or equal to
+ * the (absolute value) of the coefficent of the div in the constraints,
+ * then we can also simply drop the div.
+ *
+ * If any divs are left after these simple checks then we move on
+ * to more complicated cases in drop_more_redundant_divs.
+ */
+struct isl_basic_map *isl_basic_map_drop_redundant_divs(
+ struct isl_basic_map *bmap)
+{
+ int i, j;
+ unsigned off;
+ int *pairs = NULL;
+ int n = 0;
+
+ if (!bmap)
+ goto error;
+
+ off = isl_dim_total(bmap->dim);
+ pairs = isl_calloc_array(bmap->ctx, int, bmap->n_div);
+ if (!pairs)
+ goto error;
+
+ for (i = 0; i < bmap->n_div; ++i) {
+ int pos, neg;
+ int last_pos, last_neg;
+ int redundant;
+
+ if (!isl_int_is_zero(bmap->div[i][0]))
+ continue;
+ for (j = 0; j < bmap->n_eq; ++j)
+ if (!isl_int_is_zero(bmap->eq[j][1 + off + i]))
+ break;
+ if (j < bmap->n_eq)
+ continue;
+ ++n;
+ pos = neg = 0;
+ for (j = 0; j < bmap->n_ineq; ++j) {
+ if (isl_int_is_pos(bmap->ineq[j][1 + off + i])) {
+ last_pos = j;
+ ++pos;
+ }
+ if (isl_int_is_neg(bmap->ineq[j][1 + off + i])) {
+ last_neg = j;
+ ++neg;
+ }
+ }
+ pairs[i] = pos * neg;
+ if (pairs[i] == 0) {
+ for (j = bmap->n_ineq - 1; j >= 0; --j)
+ if (!isl_int_is_zero(bmap->ineq[j][1+off+i]))
+ isl_basic_map_drop_inequality(bmap, j);
+ bmap = isl_basic_map_drop_div(bmap, i);
+ free(pairs);
+ return isl_basic_map_drop_redundant_divs(bmap);
+ }
+ if (pairs[i] != 1)
+ continue;
+ if (!isl_seq_is_neg(bmap->ineq[last_pos] + 1,
+ bmap->ineq[last_neg] + 1,
+ off + bmap->n_div))
+ continue;
+
+ isl_int_add(bmap->ineq[last_pos][0],
+ bmap->ineq[last_pos][0], bmap->ineq[last_neg][0]);
+ isl_int_add_ui(bmap->ineq[last_pos][0],
+ bmap->ineq[last_pos][0], 1);
+ redundant = isl_int_ge(bmap->ineq[last_pos][0],
+ bmap->ineq[last_pos][1+off+i]);
+ isl_int_sub_ui(bmap->ineq[last_pos][0],
+ bmap->ineq[last_pos][0], 1);
+ isl_int_sub(bmap->ineq[last_pos][0],
+ bmap->ineq[last_pos][0], bmap->ineq[last_neg][0]);
+ if (!redundant) {
+ if (!ok_to_set_div_from_bound(bmap, i, last_pos)) {
+ pairs[i] = 0;
+ --n;
+ continue;
+ }
+ bmap = set_div_from_lower_bound(bmap, i, last_pos);
+ bmap = isl_basic_map_simplify(bmap);
+ free(pairs);
+ return isl_basic_map_drop_redundant_divs(bmap);
+ }
+ if (last_pos > last_neg) {
+ isl_basic_map_drop_inequality(bmap, last_pos);
+ isl_basic_map_drop_inequality(bmap, last_neg);
+ } else {
+ isl_basic_map_drop_inequality(bmap, last_neg);
+ isl_basic_map_drop_inequality(bmap, last_pos);
+ }
+ bmap = isl_basic_map_drop_div(bmap, i);
+ free(pairs);
+ return isl_basic_map_drop_redundant_divs(bmap);
+ }
+
+ if (n > 0)
+ return coalesce_or_drop_more_redundant_divs(bmap, pairs, n);
+
+ free(pairs);
+ return bmap;
+error:
+ free(pairs);
+ isl_basic_map_free(bmap);
+ return NULL;
+}
projects / platform / upstream / isl.git / blobdiff