isl_affine_hull.c: outside_point: fix error handling

diff --git a/isl_affine_hull.c b/isl_affine_hull.c
index 797b4cf..dcb3d18 100644 (file)
--- a/isl_affine_hull.c
+++ b/isl_affine_hull.c
@@ -295,7 +295,7 @@ static struct isl_vec *outside_point(struct isl_tab *tab, isl_int *eq, int up)
        if (!up)
                isl_seq_neg(eq, eq, 1 + dim);
 
-       if (isl_tab_rollback(tab, snap) < 0)
+       if (sample && isl_tab_rollback(tab, snap) < 0)
                goto error;
 
        return sample;