Early checking added and new test cases added for schedule fuse

src/te/schedule/schedule_lang.cc

@@ -263,10 +263,10 @@ Stage& Stage::fuse(IterVar outer, IterVar inner, IterVar* p_target) {  // NOLINT
     std::swap(outer, inner);
     std::swap(pos_inner, pos_outer);
   }
-  self->relations.push_back(FuseNode::make(outer, inner, fused));
-  all_vars->data.push_back(fused);
   CHECK_EQ(pos_inner, pos_outer + 1)
       << "Can only fuse iterations that are consecutive between each other";
+  self->relations.push_back(FuseNode::make(outer, inner, fused));
+  all_vars->data.push_back(fused);
   leaf_vars->data.erase(leaf_vars->data.begin() + pos_outer,
                         leaf_vars->data.begin() + pos_inner + 1);
   leaf_vars->data.insert(leaf_vars->data.begin() + pos_outer,

tests/python/unittest/test_lang_schedule.py

@@ -102,6 +102,49 @@ def test_fuse():
     assert any(isinstance(x, tvm.te.schedule.Fuse) for x in s[T].relations)
     assert tuple(s[T].leaf_iter_vars) == (fused, xi, yi)
 
+def test_fuse_with_split():
+    m = te.size_var('m')
+    n = te.size_var('n')
+    A = te.placeholder((m, n), name='A')
+    T = te.compute((m, n), lambda i, j: A[i, j])
+
+    s = te.create_schedule(T.op)
+    y = T.op.axis[1]
+    xo, xi = s[T].split(T.op.axis[0], factor=10)
+    fused = s[T].fuse(xi, y)
+    assert any(isinstance(x, tvm.te.schedule.Fuse) for x in s[T].relations)
+    assert tuple(s[T].leaf_iter_vars) == (xo, fused)
+
+@pytest.mark.xfail
+def test_fuse_with_out_of_order_axis():
+    m = te.size_var('m')
+    n = te.size_var('n')
+    A = te.placeholder((m, n), name='A')
+    T = te.compute((m, n), lambda i, j: A[i, j])
+
+    s = te.create_schedule(T.op)
+    y = T.op.axis[1]
+    xo, xi = s[T].split(T.op.axis[0], factor=10)
+    fused = s[T].fuse(xo, y) # should throw here
+
+@pytest.mark.xfail
+def test_fuse_with_out_of_order_axis_with_reorder():
+    m = te.size_var('m')
+    n = te.size_var('n')
+    A = te.placeholder((m, n), name='A')
+    T = te.compute((m, n), lambda i, j: A[i, j])
+
+    s = te.create_schedule(T.op)
+    y = T.op.axis[1]
+    xo, xi = s[T].split(T.op.axis[0], factor=10)
+    s[T].reorder(y, xo, xi)
+    fused = s[T].fuse(y, xo) # should be ok
+
+    s = te.create_schedule(T.op)
+    y = T.op.axis[1]
+    xo, xi = s[T].split(T.op.axis[0], factor=10)
+    s[T].reorder(y, xo, xi)
+    fused = s[T].fuse(y, xi) # should throw here
 
 def test_singleton():
     print("test singleton")
@@ -257,5 +300,8 @@ def intrin_func(ins, outs, sp):
     test_tile()
     test_split()
     test_fuse()
+    test_fuse_with_split()
+    test_fuse_with_out_of_order_axis()
+    test_fuse_with_out_of_order_axis_with_reorder()
     test_vectorize()
     test_vectorize_commreduce()