isl_sample.c: interval_sample: handle equalities directly

diff --git a/isl_sample.c b/isl_sample.c
index 4887ef6..26e8132 100644 (file)
--- a/isl_sample.c
+++ b/isl_sample.c
@@ -44,13 +44,28 @@ static struct isl_vec *interval_sample(struct isl_ctx *ctx,
        bset = isl_basic_set_simplify(bset);
        if (!bset)
                return NULL;
-       if (bset->n_eq > 0)
-               return isl_basic_set_sample(bset);
-       if (bset->n_ineq == 0)
+       if (isl_basic_set_fast_is_empty(bset))
+               return empty_sample(bset);
+       if (bset->n_eq == 0 && bset->n_ineq == 0)
                return zero_sample(bset);
 
        sample = isl_vec_alloc(ctx, 2);
        isl_int_set_si(sample->block.data[0], 1);
+
+       if (bset->n_eq > 0) {
+               isl_assert(bset->ctx, bset->n_eq == 1, goto error);
+               isl_assert(bset->ctx, bset->n_ineq == 0, goto error);
+               if (isl_int_is_one(bset->eq[0][1]))
+                       isl_int_neg(sample->el[1], bset->eq[0][0]);
+               else {
+                       isl_assert(bset->ctx, isl_int_is_negone(bset->eq[0][1]),
+                                  goto error);
+                       isl_int_set(sample->el[1], bset->eq[0][0]);
+               }
+               isl_basic_set_free(bset);
+               return sample;
+       }
+
        isl_int_init(t);
        if (isl_int_is_one(bset->ineq[0][1]))
                isl_int_neg(sample->block.data[1], bset->ineq[0][0]);
@@ -70,6 +85,10 @@ static struct isl_vec *interval_sample(struct isl_ctx *ctx,
 
        isl_basic_set_free(bset);
        return sample;
+error:
+       isl_basic_set_free(bset);
+       isl_vec_free(sample);
+       return NULL;
 }
 
 static struct isl_mat *independent_bounds(struct isl_ctx *ctx,