!14097 map a fv cnode if it is not mapped and belong to primal_graph_

From: @xychow
Reviewed-by: @ginfung,@zh_qh
Signed-off-by: @zh_qh

mindspore/ccsrc/frontend/optimizer/ad/dfunctor.cc

@@ -91,6 +91,16 @@ void DFunctor::BackPropagateFv(const AnfNodePtr &fv, const AnfNodePtr &din) {
   if (fv_adjoint == anfnode_to_adjoin_.end()) {
     MS_LOG(DEBUG) << "BackPropagateFv can not find adjoint in anfnode_to_adjoin_ fv " << fv->func_graph()->ToString()
                   << " " << fv->ToString() << ".";
+
+    if (fv->func_graph() == primal_graph_) {
+      // If this fv is not mapped by MapMorphism because of cnode order, then map it now.
+      (void)MapMorphism(fv);
+      fv_adjoint = anfnode_to_adjoin_.find(fv);
+      if (fv_adjoint == anfnode_to_adjoin_.end()) {
+        MS_LOG(EXCEPTION) << "Can not find adjoint in anfnode_to_adjoin_ fv " << fv->func_graph()->ToString() << " "
+                          << fv->ToString() << ".";
+      }
+    } else {
       fv_adjoint = anfnode_to_adjoin_indirect_fv_.find(fv);
       if (fv_adjoint == anfnode_to_adjoin_indirect_fv_.end()) {
         MS_LOG(DEBUG) << "BackPropagateFv can not find adjoint in anfnode_to_adjoin_indirect_fv_ fv "
@@ -108,6 +118,7 @@ void DFunctor::BackPropagateFv(const AnfNodePtr &fv, const AnfNodePtr &din) {
         fv_adjoint = anfnode_to_adjoin_indirect_fv_.find(fv);
       }
     }
+  }
   auto fv_node = fv_adjoint->second->k();
   auto cached_envitem_iter = anfnode_to_envitem_.find(fv_node);
   CNodePtr embed_node, default_val_node;

tests/ut/python/optimizer/test_auto_grad.py

@@ -110,3 +110,31 @@ def test_second_grad_with_j_primitive():
     second_grad = SinGradSec(first_grad)
     x = Tensor(np.array([1.0], dtype=np.float32))
     second_grad(x)
+
+
+# A CNode being used as FV is MapMorphism after MapMorphism of call-site CNode;
+def test_ad_fv_cnode_order():
+    context.set_context(mode=context.GRAPH_MODE, save_graphs=True)
+    class Net(nn.Cell):
+        def __init__(self):
+            super(Net, self).__init__()
+
+        # cnode xay is not being MapMorphism when cnode second_level() is being MapMorphism and
+        # BackPropagateFv as MapMorphism is started from output node and from left to right order.
+        def construct(self, x, y):
+            def first_level():
+                xay = x + y
+
+                def second_level():
+                    return xay
+
+                return second_level() + xay
+            return first_level()
+
+    input_x = Tensor(np.array([1.0], dtype=np.float32))
+    input_y = Tensor(np.array([2.0], dtype=np.float32))
+
+    net = Net()
+    net.add_flags_recursive(defer_inline=True)
+    grad_net = grad_all(net)
+    grad_net(input_x, input_y)