add isl_band_split

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>

diff --git a/doc/user.pod b/doc/user.pod
index f786df5..2893bc8 100644 (file)
--- a/doc/user.pod
+++ b/doc/user.pod
@@ -5128,6 +5128,13 @@ loops iterators should be scaled by the tile sizes.
 If the C<tile_shift_point_loops> option is set, then the point loops
 are shifted to start at zero.
 
+A band can be split into two nested bands using the following function.
+
+       int isl_band_split(__isl_keep isl_band *band, int pos);
+
+The resulting outer band contains the first C<pos> dimensions of C<band>
+while the inner band contains the remaining dimensions.
+
 A representation of the band can be printed using
 
        #include <isl/band.h>

diff --git a/include/isl/band.h b/include/isl/band.h
index b0809a8..a94937b 100644 (file)
--- a/include/isl/band.h
+++ b/include/isl/band.h
@@ -35,6 +35,7 @@ int isl_options_set_tile_shift_point_loops(isl_ctx *ctx, int val);
 int isl_options_get_tile_shift_point_loops(isl_ctx *ctx);
 
 int isl_band_tile(__isl_keep isl_band *band, __isl_take isl_vec *sizes);
+int isl_band_split(__isl_keep isl_band *band, int pos);
 
 int isl_band_n_member(__isl_keep isl_band *band);
 int isl_band_member_is_zero_distance(__isl_keep isl_band *band, int pos);

diff --git a/isl_band.c b/isl_band.c
index 0f8f6c4..18572d0 100644 (file)
--- a/isl_band.c
+++ b/isl_band.c
@@ -511,6 +511,119 @@ error:
        return -1;
 }
 
+/* Internal data structure used inside isl_union_pw_multi_aff_drop.
+ *
+ * "pos" is the position of the first dimension to drop.
+ * "n" is the number of dimensions to drop.
+ * "res" accumulates the result.
+ */
+struct isl_union_pw_multi_aff_drop_data {
+       int pos;
+       int n;
+       isl_union_pw_multi_aff *res;
+};
+
+/* Drop the data->n output dimensions starting at data->pos from "pma"
+ * and add the result to data->res.
+ */
+static int pw_multi_aff_drop(__isl_take isl_pw_multi_aff *pma, void *user)
+{
+       struct isl_union_pw_multi_aff_drop_data *data = user;
+
+       pma = isl_pw_multi_aff_drop_dims(pma, isl_dim_out, data->pos, data->n);
+
+       data->res = isl_union_pw_multi_aff_add_pw_multi_aff(data->res, pma);
+       if (!data->res)
+               return -1;
+
+       return 0;
+}
+
+/* Drop the "n" output dimensions starting at "pos" from "sched".
+ */
+static isl_union_pw_multi_aff *isl_union_pw_multi_aff_drop(
+       __isl_take isl_union_pw_multi_aff *sched, int pos, int n)
+{
+       isl_space *space;
+       struct isl_union_pw_multi_aff_drop_data data = { pos, n };
+
+       space = isl_union_pw_multi_aff_get_space(sched);
+       data.res = isl_union_pw_multi_aff_empty(space);
+
+       if (isl_union_pw_multi_aff_foreach_pw_multi_aff(sched,
+                                               &pw_multi_aff_drop, &data) < 0)
+               data.res = isl_union_pw_multi_aff_free(data.res);
+
+       isl_union_pw_multi_aff_free(sched);
+       return data.res;
+}
+
+/* Drop the "n" dimensions starting at "pos" from "band".
+ */
+static int isl_band_drop(__isl_keep isl_band *band, int pos, int n)
+{
+       int i;
+       isl_union_pw_multi_aff *sched;
+
+       if (!band)
+               return -1;
+       if (n == 0)
+               return 0;
+
+       sched = isl_union_pw_multi_aff_copy(band->pma);
+       sched = isl_union_pw_multi_aff_drop(sched, pos, n);
+       if (!sched)
+               return -1;
+
+       isl_union_pw_multi_aff_free(band->pma);
+       band->pma = sched;
+
+       for (i = pos + n; i < band->n; ++i)
+               band->zero[i - n] = band->zero[i];
+
+       band->n -= n;
+
+       return 0;
+}
+
+/* Split the given band into two nested bands, one with the first "pos"
+ * dimensions of "band" and one with the remaining band->n - pos dimensions.
+ */
+int isl_band_split(__isl_keep isl_band *band, int pos)
+{
+       isl_ctx *ctx;
+       isl_band *child;
+       isl_band_list *list;
+
+       if (!band)
+               return -1;
+
+       ctx = isl_band_get_ctx(band);
+
+       if (pos < 0 || pos > band->n)
+               isl_die(ctx, isl_error_invalid, "position out of bounds",
+                       return -1);
+
+       child = isl_band_dup(band);
+       if (isl_band_drop(child, 0, pos) < 0)
+               child = isl_band_free(child);
+       list = isl_band_list_alloc(ctx, 1);
+       list = isl_band_list_add(list, child);
+       if (!list)
+               return -1;
+
+       if (isl_band_drop(band, pos, band->n - pos) < 0) {
+               isl_band_list_free(list);
+               return -1;
+       }
+
+       child->children = band->children;
+       band->children = list;
+       child->parent = band;
+
+       return 0;
+}
+
 __isl_give isl_printer *isl_printer_print_band(__isl_take isl_printer *p,
        __isl_keep isl_band *band)
 {