isl_basic_map_is_empty: special case universal input

In particular, there is no need to compute any sample point on
universal inputs.

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

diff --git a/isl_map.c b/isl_map.c
index c42809c..0bccc4c 100644 (file)
--- a/isl_map.c
+++ b/isl_map.c
@@ -7283,6 +7283,9 @@ int isl_basic_map_is_empty(struct isl_basic_map *bmap)
        if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_EMPTY))
                return 1;
 
+       if (isl_basic_map_is_universe(bmap))
+               return 0;
+
        if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_RATIONAL)) {
                struct isl_basic_map *copy = isl_basic_map_copy(bmap);
                copy = isl_basic_map_remove_redundancies(copy);