isl_map_gist: handle some special cases

diff --git a/isl_map_simplify.c b/isl_map_simplify.c
index ca6b58f..f37cb2a 100644 (file)
--- a/isl_map_simplify.c
+++ b/isl_map_simplify.c
@@ -1484,6 +1484,25 @@ struct isl_basic_map *isl_basic_map_gist(struct isl_basic_map *bmap,
        if (!bmap || !context)
                goto error;
 
+       if (isl_basic_map_is_universe(context)) {
+               isl_basic_map_free(context);
+               return bmap;
+       }
+       if (isl_basic_map_is_universe(bmap)) {
+               isl_basic_map_free(context);
+               return bmap;
+       }
+       if (isl_basic_map_fast_is_empty(context)) {
+               struct isl_dim *dim = isl_dim_copy(bmap->dim);
+               isl_basic_map_free(context);
+               isl_basic_map_free(bmap);
+               return isl_basic_map_universe(dim);
+       }
+       if (isl_basic_map_fast_is_empty(bmap)) {
+               isl_basic_map_free(context);
+               return bmap;
+       }
+
        bmap = isl_basic_map_convex_hull(bmap);
        context = isl_basic_map_convex_hull(context);
 
@@ -1507,10 +1526,24 @@ struct isl_map *isl_map_gist(struct isl_map *map, struct isl_basic_map *context)
 {
        int i;
 
+       if (!map || !context)
+               goto error;;
+
+       if (isl_basic_map_is_universe(context)) {
+               isl_basic_map_free(context);
+               return map;
+       }
+       if (isl_basic_map_fast_is_empty(context)) {
+               struct isl_dim *dim = isl_dim_copy(map->dim);
+               isl_basic_map_free(context);
+               isl_map_free(map);
+               return isl_map_universe(dim);
+       }
+
        context = isl_basic_map_convex_hull(context);
        map = isl_map_cow(map);
        if (!map || !context)
-               return NULL;
+               goto error;;
        isl_assert(map->ctx, isl_dim_equal(map->dim, context->dim), goto error);
        map = isl_map_compute_divs(map);
        for (i = 0; i < map->n; ++i)