isl_map_simplify.c: break if set turns out to be empty during div coalescing

diff --git a/isl_map_simplify.c b/isl_map_simplify.c
index 9275c3b..307b93c 100644 (file)
--- a/isl_map_simplify.c
+++ b/isl_map_simplify.c
@@ -1917,6 +1917,14 @@ static int div_find_coalesce(struct isl_basic_map *bmap, int *pairs,
        }
 
        isl_int_add(bmap->ineq[l][0], bmap->ineq[l][0], bmap->ineq[u][0]);
+       if (isl_int_is_neg(bmap->ineq[l][0])) {
+               isl_int_sub(bmap->ineq[l][0],
+                           bmap->ineq[l][0], bmap->ineq[u][0]);
+               bmap = isl_basic_map_copy(bmap);
+               bmap = isl_basic_map_set_to_empty(bmap);
+               isl_basic_map_free(bmap);
+               return -1;
+       }
        isl_int_add_ui(bmap->ineq[l][0], bmap->ineq[l][0], 1);
        for (i = 0; i < bmap->n_div; ++i) {
                if (i == div)
@@ -2246,6 +2254,9 @@ static struct isl_basic_map *coalesce_or_drop_more_redundant_divs(
                }
        }
 
+       if (ISL_F_ISSET(bmap, ISL_BASIC_MAP_EMPTY))
+               return bmap;
+
        return drop_more_redundant_divs(bmap, pairs, n);
 }