isl_basic_map_affine_hull: allow computation of affine hull of rational sets
[platform/upstream/isl.git] / isl_affine_hull.c
index 13a53ca..ea08d02 100644 (file)
@@ -4,12 +4,17 @@
 #include "isl_lp.h"
 #include "isl_map.h"
 #include "isl_map_private.h"
+#include "isl_equalities.h"
+#include "isl_sample.h"
 
-struct isl_basic_map *isl_basic_map_implicit_equalities(struct isl_ctx *ctx,
+struct isl_basic_map *isl_basic_map_implicit_equalities(
                                                struct isl_basic_map *bmap)
 {
        int i;
+       int rational;
        isl_int opt;
+       isl_int opt_denom;
+       struct isl_ctx *ctx;
 
        if (!bmap)
                return bmap;
@@ -19,98 +24,85 @@ struct isl_basic_map *isl_basic_map_implicit_equalities(struct isl_ctx *ctx,
        if (F_ISSET(bmap, ISL_BASIC_MAP_NO_IMPLICIT))
                return bmap;
 
+       ctx = bmap->ctx;
+       rational = F_ISSET(bmap, ISL_BASIC_MAP_RATIONAL);
        isl_int_init(opt);
+       isl_int_init(opt_denom);
+       if (!rational)
+               isl_int_set_si(opt_denom, 1);
        for (i = 0; i < bmap->n_ineq; ++i) {
                enum isl_lp_result res;
-               res = isl_solve_lp(bmap, 1, bmap->ineq[i]+1, ctx->one, &opt);
+               res = isl_solve_lp(bmap, 1, bmap->ineq[i]+1, ctx->one,
+                                       &opt, rational ? &opt_denom : NULL);
                if (res == isl_lp_unbounded)
                        continue;
                if (res == isl_lp_error)
                        goto error;
                if (res == isl_lp_empty) {
-                       bmap = isl_basic_map_set_to_empty(ctx, bmap);
+                       bmap = isl_basic_map_set_to_empty(bmap);
                        break;
                }
+               if (!isl_int_is_one(opt_denom))
+                       continue;
                isl_int_add(opt, opt, bmap->ineq[i][0]);
                if (isl_int_is_zero(opt)) {
-                       isl_basic_map_inequality_to_equality(ctx, bmap, i);
+                       isl_basic_map_inequality_to_equality(bmap, i);
                        --i;
                }
        }
+       isl_int_clear(opt_denom);
        isl_int_clear(opt);
 
        F_SET(bmap, ISL_BASIC_MAP_NO_IMPLICIT);
        return bmap;
 error:
        isl_int_clear(opt);
-       isl_basic_map_free(ctx, bmap);
+       isl_basic_map_free(bmap);
        return NULL;
 }
 
-struct isl_basic_map *isl_basic_map_affine_hull(struct isl_ctx *ctx,
-                                               struct isl_basic_map *bmap)
-{
-       bmap = isl_basic_map_implicit_equalities(ctx, bmap);
-       if (!bmap)
-               return NULL;
-       if (bmap->n_ineq == 0)
-               return bmap;
-       bmap = isl_basic_map_cow(ctx, bmap);
-       if (!bmap)
-               return NULL;
-       isl_basic_map_free_inequality(ctx, bmap, bmap->n_ineq);
-       return isl_basic_map_finalize(ctx, bmap);
-}
-
-struct isl_basic_set *isl_basic_set_affine_hull(struct isl_ctx *ctx,
-                                               struct isl_basic_set *bset)
-{
-       return (struct isl_basic_set *)
-               isl_basic_map_affine_hull(ctx, (struct isl_basic_map *)bset);
-}
-
 /* Make eq[row][col] of both bmaps equal so we can add the row
  * add the column to the common matrix.
  * Note that because of the echelon form, the columns of row row
  * after column col are zero.
  */
 static void set_common_multiple(
-       struct isl_basic_map *bmap1, struct isl_basic_map *bmap2,
+       struct isl_basic_set *bset1, struct isl_basic_set *bset2,
        unsigned row, unsigned col)
 {
        isl_int m, c;
 
-       if (isl_int_eq(bmap1->eq[row][col], bmap2->eq[row][col]))
+       if (isl_int_eq(bset1->eq[row][col], bset2->eq[row][col]))
                return;
 
        isl_int_init(c);
        isl_int_init(m);
-       isl_int_lcm(m, bmap1->eq[row][col], bmap2->eq[row][col]);
-       isl_int_divexact(c, m, bmap1->eq[row][col]);
-       isl_seq_scale(bmap1->eq[row], bmap1->eq[row], c, col+1);
-       isl_int_divexact(c, m, bmap2->eq[row][col]);
-       isl_seq_scale(bmap2->eq[row], bmap2->eq[row], c, col+1);
+       isl_int_lcm(m, bset1->eq[row][col], bset2->eq[row][col]);
+       isl_int_divexact(c, m, bset1->eq[row][col]);
+       isl_seq_scale(bset1->eq[row], bset1->eq[row], c, col+1);
+       isl_int_divexact(c, m, bset2->eq[row][col]);
+       isl_seq_scale(bset2->eq[row], bset2->eq[row], c, col+1);
        isl_int_clear(c);
        isl_int_clear(m);
 }
 
 /* Delete a given equality, moving all the following equalities one up.
  */
-static void delete_row(struct isl_basic_map *bmap, unsigned row)
+static void delete_row(struct isl_basic_set *bset, unsigned row)
 {
        isl_int *t;
        int r;
 
-       t = bmap->eq[row];
-       bmap->n_eq--;
-       for (r = row; r < bmap->n_eq; ++r)
-               bmap->eq[r] = bmap->eq[r+1];
-       bmap->eq[bmap->n_eq] = t;
+       t = bset->eq[row];
+       bset->n_eq--;
+       for (r = row; r < bset->n_eq; ++r)
+               bset->eq[r] = bset->eq[r+1];
+       bset->eq[bset->n_eq] = t;
 }
 
-/* Make first row entries in column col of bmap1 identical to
- * those of bmap2, using the fact that entry bmap1->eq[row][col]=a
- * is non-zero.  Initially, these elements of bmap1 are all zero.
+/* Make first row entries in column col of bset1 identical to
+ * those of bset2, using the fact that entry bset1->eq[row][col]=a
+ * is non-zero.  Initially, these elements of bset1 are all zero.
  * For each row i < row, we set
  *             A[i] = a * A[i] + B[i][col] * A[row]
  *             B[i] = a * B[i]
@@ -118,7 +110,7 @@ static void delete_row(struct isl_basic_map *bmap, unsigned row)
  *             A[i][col] = B[i][col] = a * old(B[i][col])
  */
 static void construct_column(
-       struct isl_basic_map *bmap1, struct isl_basic_map *bmap2,
+       struct isl_basic_set *bset1, struct isl_basic_set *bset2,
        unsigned row, unsigned col)
 {
        int r;
@@ -128,24 +120,24 @@ static void construct_column(
 
        isl_int_init(a);
        isl_int_init(b);
-       total = 1 + bmap1->nparam + bmap1->n_in + bmap1->n_out + bmap1->n_div;
+       total = 1 + bset1->dim;
        for (r = 0; r < row; ++r) {
-               if (isl_int_is_zero(bmap2->eq[r][col]))
+               if (isl_int_is_zero(bset2->eq[r][col]))
                        continue;
-               isl_int_gcd(b, bmap2->eq[r][col], bmap1->eq[row][col]);
-               isl_int_divexact(a, bmap1->eq[row][col], b);
-               isl_int_divexact(b, bmap2->eq[r][col], b);
-               isl_seq_combine(bmap1->eq[r], a, bmap1->eq[r],
-                                             b, bmap1->eq[row], total);
-               isl_seq_scale(bmap2->eq[r], bmap2->eq[r], a, total);
+               isl_int_gcd(b, bset2->eq[r][col], bset1->eq[row][col]);
+               isl_int_divexact(a, bset1->eq[row][col], b);
+               isl_int_divexact(b, bset2->eq[r][col], b);
+               isl_seq_combine(bset1->eq[r], a, bset1->eq[r],
+                                             b, bset1->eq[row], total);
+               isl_seq_scale(bset2->eq[r], bset2->eq[r], a, total);
        }
        isl_int_clear(a);
        isl_int_clear(b);
-       delete_row(bmap1, row);
+       delete_row(bset1, row);
 }
 
-/* Make first row entries in column col of bmap1 identical to
- * those of bmap2, using only these entries of the two matrices.
+/* Make first row entries in column col of bset1 identical to
+ * those of bset2, using only these entries of the two matrices.
  * Let t be the last row with different entries.
  * For each row i < t, we set
  *     A[i] = (A[t][col]-B[t][col]) * A[i] + (B[i][col]-A[i][col) * A[t]
@@ -154,7 +146,7 @@ static void construct_column(
  *     A[i][col] = B[i][col] = old(A[t][col]*B[i][col]-A[i][col]*B[t][col])
  */
 static int transform_column(
-       struct isl_basic_map *bmap1, struct isl_basic_map *bmap2,
+       struct isl_basic_set *bset1, struct isl_basic_set *bset2,
        unsigned row, unsigned col)
 {
        int i, t;
@@ -162,31 +154,31 @@ static int transform_column(
        unsigned total;
 
        for (t = row-1; t >= 0; --t)
-               if (isl_int_ne(bmap1->eq[t][col], bmap2->eq[t][col]))
+               if (isl_int_ne(bset1->eq[t][col], bset2->eq[t][col]))
                        break;
        if (t < 0)
                return 0;
 
-       total = 1 + bmap1->nparam + bmap1->n_in + bmap1->n_out + bmap1->n_div;
+       total = 1 + bset1->dim;
        isl_int_init(a);
        isl_int_init(b);
        isl_int_init(g);
-       isl_int_sub(b, bmap1->eq[t][col], bmap2->eq[t][col]);
+       isl_int_sub(b, bset1->eq[t][col], bset2->eq[t][col]);
        for (i = 0; i < t; ++i) {
-               isl_int_sub(a, bmap2->eq[i][col], bmap1->eq[i][col]);
+               isl_int_sub(a, bset2->eq[i][col], bset1->eq[i][col]);
                isl_int_gcd(g, a, b);
                isl_int_divexact(a, a, g);
                isl_int_divexact(g, b, g);
-               isl_seq_combine(bmap1->eq[i], g, bmap1->eq[i], a, bmap1->eq[t],
+               isl_seq_combine(bset1->eq[i], g, bset1->eq[i], a, bset1->eq[t],
                                total);
-               isl_seq_combine(bmap2->eq[i], g, bmap2->eq[i], a, bmap2->eq[t],
+               isl_seq_combine(bset2->eq[i], g, bset2->eq[i], a, bset2->eq[t],
                                total);
        }
        isl_int_clear(a);
        isl_int_clear(b);
        isl_int_clear(g);
-       delete_row(bmap1, t);
-       delete_row(bmap2, t);
+       delete_row(bset1, t);
+       delete_row(bset2, t);
        return 1;
 }
 
@@ -195,84 +187,250 @@ static int transform_column(
  * except that the echelon form we use starts from the last column
  * and that we are dealing with integer coefficients.
  */
-static struct isl_basic_map *affine_hull(struct isl_ctx *ctx,
-       struct isl_basic_map *bmap1, struct isl_basic_map *bmap2)
+static struct isl_basic_set *affine_hull(
+       struct isl_basic_set *bset1, struct isl_basic_set *bset2)
 {
        unsigned total;
        int col;
        int row;
 
-       total = 1 + bmap1->nparam + bmap1->n_in + bmap1->n_out + bmap1->n_div;
+       total = 1 + bset1->dim;
 
        row = 0;
        for (col = total-1; col >= 0; --col) {
-               int is_zero1 = row >= bmap1->n_eq ||
-                       isl_int_is_zero(bmap1->eq[row][col]);
-               int is_zero2 = row >= bmap2->n_eq ||
-                       isl_int_is_zero(bmap2->eq[row][col]);
+               int is_zero1 = row >= bset1->n_eq ||
+                       isl_int_is_zero(bset1->eq[row][col]);
+               int is_zero2 = row >= bset2->n_eq ||
+                       isl_int_is_zero(bset2->eq[row][col]);
                if (!is_zero1 && !is_zero2) {
-                       set_common_multiple(bmap1, bmap2, row, col);
+                       set_common_multiple(bset1, bset2, row, col);
                        ++row;
                } else if (!is_zero1 && is_zero2) {
-                       construct_column(bmap1, bmap2, row, col);
+                       construct_column(bset1, bset2, row, col);
                } else if (is_zero1 && !is_zero2) {
-                       construct_column(bmap2, bmap1, row, col);
+                       construct_column(bset2, bset1, row, col);
                } else {
-                       if (transform_column(bmap1, bmap2, row, col))
+                       if (transform_column(bset1, bset2, row, col))
                                --row;
                }
        }
-       isl_basic_map_free(ctx, bmap2);
-       return bmap1;
+       isl_basic_set_free(bset2);
+       isl_assert(ctx, row == bset1->n_eq, goto error);
+       return bset1;
+error:
+       isl_basic_set_free(bset1);
+       return NULL;
 }
 
-struct isl_basic_map *isl_map_affine_hull(struct isl_ctx *ctx,
-                                               struct isl_map *map)
+static struct isl_basic_set *isl_basic_set_from_vec(struct isl_ctx *ctx,
+       struct isl_vec *vec)
 {
        int i;
-       struct isl_basic_map *bmap;
+       int k;
+       struct isl_basic_set *bset = NULL;
+
+       if (!vec)
+               return NULL;
+       isl_assert(ctx, vec->size != 0, goto error);
+
+       bset = isl_basic_set_alloc(ctx, 0, vec->size - 1, 0, vec->size - 1, 0);
+       for (i = bset->dim - 1; i >= 0; --i) {
+               k = isl_basic_set_alloc_equality(bset);
+               if (k < 0)
+                       goto error;
+               isl_seq_clr(bset->eq[k], 1 + bset->dim);
+               isl_int_neg(bset->eq[k][0], vec->block.data[1 + i]);
+               isl_int_set(bset->eq[k][1 + i], vec->block.data[0]);
+       }
+       isl_vec_free(ctx, vec);
+
+       return bset;
+error:
+       isl_basic_set_free(bset);
+       isl_vec_free(ctx, vec);
+       return NULL;
+}
+
+static struct isl_basic_set *outside_point(struct isl_ctx *ctx,
+       struct isl_basic_set *bset, isl_int *eq, int up)
+{
+       struct isl_basic_set *slice = NULL;
+       struct isl_vec *sample;
+       struct isl_basic_set *point;
+       int k;
+
+       slice = isl_basic_set_copy(bset);
+       if (!slice)
+               goto error;
+       slice = isl_basic_set_extend(slice, 0, slice->dim, 0, 1, 0);
+       k = isl_basic_set_alloc_equality(slice);
+       if (k < 0)
+               goto error;
+       isl_seq_cpy(slice->eq[k], eq, 1 + slice->dim);
+       if (up)
+               isl_int_add_ui(slice->eq[k][0], slice->eq[k][0], 1);
+       else
+               isl_int_sub_ui(slice->eq[k][0], slice->eq[k][0], 1);
+
+       sample = isl_basic_set_sample(slice);
+       if (!sample)
+               goto error;
+       if (sample->size == 0) {
+               isl_vec_free(ctx, sample);
+               point = isl_basic_set_empty(ctx, 0, bset->dim);
+       } else
+               point = isl_basic_set_from_vec(ctx, sample);
+
+       return point;
+error:
+       isl_basic_set_free(slice);
+       return NULL;
+}
+
+/* After computing the rational affine hull (by detecting the implicit
+ * equalities), we remove all equalities found so far, compute
+ * the integer affine hull of what is left, and then add the original
+ * equalities back in.
+ *
+ * The integer affine hull is constructed by successively looking
+ * a point that is affinely independent of the points found so far.
+ * In particular, for each equality satisfied by the points so far,
+ * we check if there is any point on the corresponding hyperplane
+ * shifted by one (in either direction).
+ */
+struct isl_basic_map *isl_basic_map_affine_hull(struct isl_basic_map *bmap)
+{
+       int i, j;
+       struct isl_mat *T2 = NULL;
+       struct isl_basic_set *bset = NULL;
+       struct isl_basic_set *hull = NULL;
+       struct isl_vec *sample;
+       struct isl_ctx *ctx;
+
+       bmap = isl_basic_map_implicit_equalities(bmap);
+       if (!bmap)
+               return NULL;
+       ctx = bmap->ctx;
+       if (bmap->n_ineq == 0)
+               return bmap;
+
+       if (F_ISSET(bmap, ISL_BASIC_MAP_RATIONAL)) {
+               bmap = isl_basic_map_cow(bmap);
+               isl_basic_map_free_inequality(bmap, bmap->n_ineq);
+               return bmap;
+       }
+
+       bset = isl_basic_map_underlying_set(isl_basic_map_copy(bmap));
+       bset = isl_basic_set_remove_equalities(bset, NULL, &T2);
+
+       sample = isl_basic_set_sample(isl_basic_set_copy(bset));
+       hull = isl_basic_set_from_vec(ctx, sample);
+
+       for (i = 0; i < bset->dim; ++i) {
+               struct isl_basic_set *point;
+               for (j = 0; j < hull->n_eq; ++j) {
+                       point = outside_point(ctx, bset, hull->eq[j], 1);
+                       if (!point)
+                               goto error;
+                       if (!F_ISSET(point, ISL_BASIC_SET_EMPTY))
+                               break;
+                       isl_basic_set_free(point);
+                       point = outside_point(ctx, bset, hull->eq[j], 0);
+                       if (!point)
+                               goto error;
+                       if (!F_ISSET(point, ISL_BASIC_SET_EMPTY))
+                               break;
+                       isl_basic_set_free(point);
+               }
+               if (j == hull->n_eq)
+                       break;
+               hull = affine_hull(hull, point);
+       }
+
+       isl_basic_set_free(bset);
+       bset = NULL;
+       bmap = isl_basic_map_cow(bmap);
+       if (!bmap)
+               goto error;
+       isl_basic_map_free_inequality(bmap, bmap->n_ineq);
+       if (T2)
+               hull = isl_basic_set_preimage(ctx, hull, T2);
+       bmap = isl_basic_map_intersect(bmap,
+                                       isl_basic_map_overlying_set(hull,
+                                               isl_basic_map_copy(bmap)));
+
+       return isl_basic_map_finalize(bmap);
+error:
+       isl_mat_free(ctx, T2);
+       isl_basic_set_free(bset);
+       isl_basic_set_free(hull);
+       isl_basic_map_free(bmap);
+       return NULL;
+}
+
+struct isl_basic_set *isl_basic_set_affine_hull(struct isl_basic_set *bset)
+{
+       return (struct isl_basic_set *)
+               isl_basic_map_affine_hull((struct isl_basic_map *)bset);
+}
+
+struct isl_basic_map *isl_map_affine_hull(struct isl_map *map)
+{
+       int i;
+       struct isl_basic_map *model = NULL;
+       struct isl_basic_map *hull = NULL;
+       struct isl_set *set;
 
-       map = isl_map_compute_divs(ctx, map);
-       map = isl_map_cow(ctx, map);
        if (!map)
                return NULL;
 
        if (map->n == 0) {
-               bmap = isl_basic_map_empty(ctx,
-                                           map->nparam, map->n_in, map->n_out);
-               isl_map_free(ctx, map);
-               return bmap;
+               hull = isl_basic_map_empty(map->ctx,
+                                       map->nparam, map->n_in, map->n_out);
+               isl_map_free(map);
+               return hull;
        }
 
-       for (i = 1; i < map->n; ++i)
-               map->p[0] = isl_basic_map_align_divs(ctx, map->p[0], map->p[i]);
-       for (i = 1; i < map->n; ++i)
-               map->p[i] = isl_basic_map_align_divs(ctx, map->p[i], map->p[0]);
+       map = isl_map_align_divs(map);
+       model = isl_basic_map_copy(map->p[0]);
+       set = isl_map_underlying_set(map);
+       set = isl_set_cow(set);
+       if (!set)
+               goto error;
 
-       for (i = 0; i < map->n; ++i) {
-               map->p[i] = isl_basic_map_cow(ctx, map->p[i]);
-               map->p[i] = isl_basic_map_affine_hull(ctx, map->p[i]);
-               map->p[i] = isl_basic_map_gauss(ctx, map->p[i], NULL);
-               if (!map->p[i])
+       for (i = 0; i < set->n; ++i) {
+               set->p[i] = isl_basic_set_cow(set->p[i]);
+               set->p[i] = isl_basic_set_affine_hull(set->p[i]);
+               set->p[i] = isl_basic_set_gauss(set->p[i], NULL);
+               if (!set->p[i])
                        goto error;
        }
-       while (map->n > 1) {
-               map->p[0] = affine_hull(ctx, map->p[0], map->p[--map->n]);
-               if (!map->p[0])
-                       goto error;
+       set = isl_set_remove_empty_parts(set);
+       if (set->n == 0) {
+               hull = isl_basic_map_empty(set->ctx,
+                                   model->nparam, model->n_in, model->n_out);
+               isl_basic_map_free(model);
+       } else {
+               struct isl_basic_set *bset;
+               while (set->n > 1) {
+                       set->p[0] = affine_hull(set->p[0], set->p[--set->n]);
+                       if (!set->p[0])
+                               goto error;
+               }
+               bset = isl_basic_set_copy(set->p[0]);
+               hull = isl_basic_map_overlying_set(bset, model);
        }
-       bmap = isl_basic_map_copy(ctx, map->p[0]);
-       isl_map_free(ctx, map);
-       bmap = isl_basic_map_finalize(ctx, bmap);
-       return isl_basic_map_simplify(ctx, bmap);
+       isl_set_free(set);
+       hull = isl_basic_map_simplify(hull);
+       return isl_basic_map_finalize(hull);
 error:
-       isl_map_free(ctx, map);
+       isl_basic_map_free(model);
+       isl_set_free(set);
        return NULL;
 }
 
-struct isl_basic_set *isl_set_affine_hull(struct isl_ctx *ctx,
-                                               struct isl_set *set)
+struct isl_basic_set *isl_set_affine_hull(struct isl_set *set)
 {
        return (struct isl_basic_set *)
-               isl_map_affine_hull(ctx, (struct isl_map *)set);
+               isl_map_affine_hull((struct isl_map *)set);
 }