isl_pip_basic_map_compute_divs: remove some equalities first

diff --git a/isl_map_piplib.c b/isl_map_piplib.c
index 1a12e83..25d223b 100644 (file)
--- a/isl_map_piplib.c
+++ b/isl_map_piplib.c
@@ -1,9 +1,11 @@
 #include "isl_set.h"
 #include "isl_map.h"
+#include "isl_mat.h"
 #include "isl_seq.h"
 #include "isl_piplib.h"
 #include "isl_map_piplib.h"
 #include "isl_map_private.h"
+#include "isl_equalities.h"
 
 static void copy_values_from(isl_int *dst, Entier *src, unsigned n)
 {
@@ -483,7 +485,7 @@ struct isl_map *isl_pip_basic_map_lexmin(
  * The output has the same parameters, but no output variables, only
  * explicit existentially quantified variables.
  */
-static struct isl_set *compute_divs(struct isl_basic_set *bset)
+static struct isl_set *compute_divs_no_eq(struct isl_basic_set *bset)
 {
        PipMatrix *domain = NULL, *context = NULL;
        PipOptions      *options;
@@ -558,6 +560,235 @@ error:
        return NULL;
 }
 
+static struct isl_set *isl_set_reset_dim(struct isl_set *set,
+       struct isl_dim *dim)
+{
+       return (struct isl_set *) isl_map_reset_dim((struct isl_map *)set, dim);
+}
+
+/* Given a matrix M (mat) and a size n (size), replace mat
+ * by the matrix
+ *
+ *             [ M 0 ]
+ *             [ 0 I ]
+ *
+ * where I is an n x n identity matrix.
+ */
+static struct isl_mat *append_identity(struct isl_ctx *ctx,
+       struct isl_mat *mat, unsigned size)
+{
+       int i;
+       unsigned n_row, n_col;
+
+       n_row = mat->n_row;
+       n_col = mat->n_col;
+       mat = isl_mat_extend(ctx, mat, n_row + size, n_col + size);
+       if (!mat)
+               return NULL;
+       for (i = 0; i < n_row; ++i)
+               isl_seq_clr(mat->row[i] + n_col, size);
+       for (i = 0; i < size; ++i) {
+               isl_seq_clr(mat->row[n_row + i], n_col + size);
+               isl_int_set_si(mat->row[n_row + i][n_col + i], 1);
+       }
+       return mat;
+}
+
+/* Apply a preimage specified by "mat" on the parameters of "bset".
+ */
+static struct isl_basic_set *basic_set_parameter_preimage(
+       struct isl_basic_set *bset, struct isl_mat *mat)
+{
+       unsigned nparam, n_out;
+
+       if (!bset || !mat)
+               goto error;
+
+       bset->dim = isl_dim_cow(bset->dim);
+       if (!bset->dim)
+               goto error;
+
+       nparam = isl_basic_set_dim(bset, isl_dim_param);
+       n_out = isl_basic_set_dim(bset, isl_dim_set);
+
+       isl_assert(bset->ctx, mat->n_row == 1 + nparam, goto error);
+
+       mat = append_identity(bset->ctx, mat, n_out);
+       if (!mat)
+               goto error;
+
+       bset->dim->nparam = 0;
+       bset->dim->n_out += nparam;
+       bset = isl_basic_set_preimage(bset, mat);
+       if (bset) {
+               bset->dim->nparam = bset->dim->n_out - n_out;
+               bset->dim->n_out = n_out;
+       }
+       return bset;
+error:
+       isl_mat_free(bset ? bset->ctx : NULL, mat);
+       isl_basic_set_free(bset);
+       return NULL;
+}
+
+/* Apply a preimage specified by "mat" on the parameters of "set".
+ */
+static struct isl_set *set_parameter_preimage(
+       struct isl_set *set, struct isl_mat *mat)
+{
+       struct isl_dim *dim = NULL;
+       unsigned nparam, n_out;
+
+       if (!set || !mat)
+               goto error;
+
+       dim = isl_dim_copy(set->dim);
+       dim = isl_dim_cow(dim);
+       if (!dim)
+               goto error;
+
+       nparam = isl_set_dim(set, isl_dim_param);
+       n_out = isl_set_dim(set, isl_dim_set);
+
+       isl_assert(set->ctx, mat->n_row == 1 + nparam, goto error);
+
+       mat = append_identity(set->ctx, mat, n_out);
+       if (!mat)
+               goto error;
+
+       dim->nparam = 0;
+       dim->n_out += nparam;
+       isl_set_reset_dim(set, dim);
+       set = isl_set_preimage(set, mat);
+       if (!set)
+               goto error2;
+       dim = isl_dim_copy(set->dim);
+       dim = isl_dim_cow(dim);
+       if (!dim)
+               goto error2;
+       dim->nparam = dim->n_out - n_out;
+       dim->n_out = n_out;
+       isl_set_reset_dim(set, dim);
+       return set;
+error:
+       isl_dim_free(dim);
+       isl_mat_free(set ? set->ctx : NULL, mat);
+error2:
+       isl_set_free(set);
+       return NULL;
+}
+
+/* Intersect the basic set "bset" with the affine space specified by the
+ * equalities in "eq".
+ */
+static struct isl_basic_set *basic_set_append_equalities(
+       struct isl_basic_set *bset, struct isl_mat *eq)
+{
+       int i, k;
+       unsigned len;
+
+       if (!bset || !eq)
+               goto error;
+
+       bset = isl_basic_set_extend_dim(bset, isl_dim_copy(bset->dim), 0,
+                                       eq->n_row, 0);
+       if (!bset)
+               goto error;
+
+       len = 1 + isl_dim_total(bset->dim) + bset->extra;
+       for (i = 0; i < eq->n_row; ++i) {
+               k = isl_basic_set_alloc_equality(bset);
+               if (k < 0)
+                       goto error;
+               isl_seq_cpy(bset->eq[k], eq->row[i], eq->n_col);
+               isl_seq_clr(bset->eq[k] + eq->n_col, len - eq->n_col);
+       }
+       isl_mat_free(bset->ctx, eq);
+
+       return bset;
+error:
+       isl_mat_free(bset ? bset->ctx : NULL, eq);
+       isl_basic_set_free(bset);
+       return NULL;
+}
+
+/* Intersect the set "set" with the affine space specified by the
+ * equalities in "eq".
+ */
+static struct isl_set *set_append_equalities(struct isl_set *set,
+       struct isl_mat *eq)
+{
+       int i;
+
+       if (!set || !eq)
+               goto error;
+
+       for (i = 0; i < set->n; ++i) {
+               set->p[i] = basic_set_append_equalities(set->p[i],
+                                       isl_mat_copy(set->ctx, eq));
+               if (!set->p[i])
+                       goto error;
+       }
+       isl_mat_free(set->ctx, eq);
+       return set;
+error:
+       isl_mat_free(set ? set->ctx : NULL, eq);
+       isl_set_free(set);
+       return NULL;
+}
+
+/* Project the given basic set onto its parameter domain, possibly introducing
+ * new, explicit, existential variables in the constraints.
+ * The input has parameters and output variables.
+ * The output has the same parameters, but no output variables, only
+ * explicit existentially quantified variables.
+ *
+ * The actual projection is performed by pip, but pip doesn't seem
+ * to like equalities very much, so we first remove the equalities
+ * among the parameters by performing a variable compression on
+ * the parameters.  Afterward, an inverse transformation is performed
+ * and the equalities among the parameters are inserted back in.
+ */
+static struct isl_set *compute_divs(struct isl_basic_set *bset)
+{
+       int i, j;
+       struct isl_mat *eq;
+       struct isl_mat *T, *T2;
+       struct isl_set *set;
+       unsigned nparam, n_out;
+
+       bset = isl_basic_set_cow(bset);
+       if (!bset)
+               return NULL;
+
+       if (bset->n_eq == 0)
+               return compute_divs_no_eq(bset);
+
+       isl_basic_set_gauss(bset, NULL);
+
+       nparam = isl_basic_set_dim(bset, isl_dim_param);
+       n_out = isl_basic_set_dim(bset, isl_dim_out);
+
+       for (i = 0, j = n_out - 1; i < bset->n_eq && j >= 0; --j) {
+               if (!isl_int_is_zero(bset->eq[i][1 + nparam + j]))
+                       ++i;
+       }
+       if (i == bset->n_eq)
+               return compute_divs_no_eq(bset);
+
+       eq = isl_mat_sub_alloc(bset->ctx, bset->eq, i, bset->n_eq - i,
+               0, 1 + nparam);
+       eq = isl_mat_cow(bset->ctx, eq);
+       T = isl_mat_variable_compression(bset->ctx,
+               isl_mat_copy(bset->ctx, eq), &T2);
+       bset = basic_set_parameter_preimage(bset, T);
+
+       set = compute_divs_no_eq(bset);
+       set = set_parameter_preimage(set, T2);
+       set = set_append_equalities(set, eq);
+       return set;
+}
+
 /* Compute an explicit representation for all the existentially
  * quantified variables.
  * The input and output dimensions are first turned into parameters