isl_map_inline_foreach_basic_map: drop basic maps that have become empty

In particular, drop basic maps that have become empty in
isl_map_detect_equalities (which calls isl_map_inline_foreach_basic_map).

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

diff --git a/isl_affine_hull.c b/isl_affine_hull.c
index e71bc10..edfefe4 100644 (file)
--- a/isl_affine_hull.c
+++ b/isl_affine_hull.c
@@ -1126,30 +1126,6 @@ __isl_give isl_basic_set *isl_basic_set_detect_equalities(
                isl_basic_map_detect_equalities((isl_basic_map *)bset);
 }
 
-__isl_give isl_map *isl_map_inline_foreach_basic_map(__isl_take isl_map *map,
-       __isl_give isl_basic_map *(*fn)(__isl_take isl_basic_map *bmap))
-{
-       struct isl_basic_map *bmap;
-       int i;
-
-       if (!map)
-               return NULL;
-
-       for (i = 0; i < map->n; ++i) {
-               bmap = isl_basic_map_copy(map->p[i]);
-               bmap = fn(bmap);
-               if (!bmap)
-                       goto error;
-               isl_basic_map_free(map->p[i]);
-               map->p[i] = bmap;
-       }
-
-       return map;
-error:
-       isl_map_free(map);
-       return NULL;
-}
-
 __isl_give isl_map *isl_map_detect_equalities(__isl_take isl_map *map)
 {
        return isl_map_inline_foreach_basic_map(map,

diff --git a/isl_map.c b/isl_map.c
index 51a8600..b0554cf 100644 (file)
--- a/isl_map.c
+++ b/isl_map.c
@@ -5331,6 +5331,39 @@ static int remove_if_empty(__isl_keep isl_map *map, int i)
        return 0;
 }
 
+/* Perform "fn" on each basic map of "map", where we may not be holding
+ * the only reference to "map".
+ * In particular, "fn" should be a semantics preserving operation
+ * that we want to apply to all copies of "map".  We therefore need
+ * to be careful not to modify "map" in a way that breaks "map"
+ * in case anything goes wrong.
+ */
+__isl_give isl_map *isl_map_inline_foreach_basic_map(__isl_take isl_map *map,
+       __isl_give isl_basic_map *(*fn)(__isl_take isl_basic_map *bmap))
+{
+       struct isl_basic_map *bmap;
+       int i;
+
+       if (!map)
+               return NULL;
+
+       for (i = map->n - 1; i >= 0; --i) {
+               bmap = isl_basic_map_copy(map->p[i]);
+               bmap = fn(bmap);
+               if (!bmap)
+                       goto error;
+               isl_basic_map_free(map->p[i]);
+               map->p[i] = bmap;
+               if (remove_if_empty(map, i) < 0)
+                       goto error;
+       }
+
+       return map;
+error:
+       isl_map_free(map);
+       return NULL;
+}
+
 struct isl_map *isl_map_fix_si(struct isl_map *map,
                enum isl_dim_type type, unsigned pos, int value)
 {