isl_pip_basic_map_compute_divs: don't turn divs into output dimensions

There is no practical reason why we should want to do this transformation
and removing it makes it possible to you use the standard interface
to pip in the next commit.

diff --git a/isl_map_piplib.c b/isl_map_piplib.c
index b38a7c1..8a495eb 100644 (file)
--- a/isl_map_piplib.c
+++ b/isl_map_piplib.c
@@ -553,39 +553,13 @@ static struct isl_set *isl_set_reset_dim(struct isl_set *set,
        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_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(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".
+ * bset is assumed to have only parameters and divs.
  */
 static struct isl_basic_set *basic_set_parameter_preimage(
        struct isl_basic_set *bset, struct isl_mat *mat)
 {
-       unsigned nparam, n_out;
+       unsigned nparam;
 
        if (!bset || !mat)
                goto error;
@@ -595,20 +569,15 @@ static struct isl_basic_set *basic_set_parameter_preimage(
                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(mat, n_out);
-       if (!mat)
-               goto error;
-
        bset->dim->nparam = 0;
-       bset->dim->n_out += nparam;
+       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;
+               bset->dim->nparam = bset->dim->n_out;
+               bset->dim->n_out = 0;
        }
        return bset;
 error:
@@ -618,12 +587,13 @@ error:
 }
 
 /* Apply a preimage specified by "mat" on the parameters of "set".
+ * set is assumed to have only parameters and divs.
  */
 static struct isl_set *set_parameter_preimage(
        struct isl_set *set, struct isl_mat *mat)
 {
        struct isl_dim *dim = NULL;
-       unsigned nparam, n_out;
+       unsigned nparam;
 
        if (!set || !mat)
                goto error;
@@ -634,16 +604,11 @@ static struct isl_set *set_parameter_preimage(
                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(mat, n_out);
-       if (!mat)
-               goto error;
-
        dim->nparam = 0;
-       dim->n_out += nparam;
+       dim->n_out = nparam;
        isl_set_reset_dim(set, dim);
        set = isl_set_preimage(set, mat);
        if (!set)
@@ -652,8 +617,8 @@ static struct isl_set *set_parameter_preimage(
        dim = isl_dim_cow(dim);
        if (!dim)
                goto error2;
-       dim->nparam = dim->n_out - n_out;
-       dim->n_out = n_out;
+       dim->nparam = dim->n_out;
+       dim->n_out = 0;
        isl_set_reset_dim(set, dim);
        return set;
 error:
@@ -725,8 +690,8 @@ error:
 
 /* 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
+ * The input has parameters and (possibly implicit) existential variables.
+ * The output has the same parameters, but only
  * explicit existentially quantified variables.
  *
  * The actual projection is performed by pip, but pip doesn't seem
@@ -741,7 +706,7 @@ static struct isl_set *compute_divs(struct isl_basic_set *bset)
        struct isl_mat *eq;
        struct isl_mat *T, *T2;
        struct isl_set *set;
-       unsigned nparam, n_out;
+       unsigned nparam, n_div;
 
        bset = isl_basic_set_cow(bset);
        if (!bset)
@@ -753,9 +718,9 @@ static struct isl_set *compute_divs(struct isl_basic_set *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);
+       n_div = isl_basic_set_dim(bset, isl_dim_div);
 
-       for (i = 0, j = n_out - 1; i < bset->n_eq && j >= 0; --j) {
+       for (i = 0, j = n_div - 1; i < bset->n_eq && j >= 0; --j) {
                if (!isl_int_is_zero(bset->eq[i][1 + nparam + j]))
                        ++i;
        }
@@ -776,8 +741,7 @@ static struct isl_set *compute_divs(struct isl_basic_set *bset)
 
 /* Compute an explicit representation for all the existentially
  * quantified variables.
- * The input and output dimensions are first turned into parameters
- * and the existential variables into output dimensions.
+ * The input and output dimensions are first turned into parameters.
  * compute_divs then returns a map with the same parameters and
  * no input or output dimensions and the dimension specification
  * is reset to that of the input.
@@ -799,14 +763,12 @@ struct isl_map *isl_pip_basic_map_compute_divs(struct isl_basic_map *bmap)
        nparam = isl_basic_map_dim(bmap, isl_dim_param);
        n_in = isl_basic_map_dim(bmap, isl_dim_in);
        n_out = isl_basic_map_dim(bmap, isl_dim_out);
-       dim = isl_dim_set_alloc(bmap->ctx, nparam + n_in + n_out, bmap->n_div);
+       dim = isl_dim_set_alloc(bmap->ctx, nparam + n_in + n_out, 0);
        if (!dim)
                goto error;
 
        orig_dim = bmap->dim;
        bmap->dim = dim;
-       bmap->extra -= bmap->n_div;
-       bmap->n_div = 0;
        bset = (struct isl_basic_set *)bmap;
 
        set = compute_divs(bset);