fix(mge/core): fix Tensor deepcopy issue

GitOrigin-RevId: 6bea7970b8319fc54458c6b1d3cd2545cca3c0c0

python_module/megengine/core/tensor.py

@@ -6,6 +6,7 @@
 # software distributed under the License is distributed on an
 # "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 import collections
+import copy
 import functools
 import itertools
 import weakref
@@ -674,6 +675,22 @@ class Tensor:
         snd = mgb.make_shared(device, value=data, dtype=dtype)
         self._reset(snd, requires_grad=requires_grad)
 
+    def __deepcopy__(self, memo):
+        """
+        Since Tensor have __getstate__ and __setstate__ method,
+        deepcopy only process the that and ignore the attribute of Parameter.
+        So we need to add __deepcopy__ method to deepcopy correct attribute.
+        """
+        assert (self.__val is not None) and (
+            self.__sym is None
+        ), "Only SharedND initialized Tensor can be serialized or deep copied"
+        cls = self.__class__
+        result = cls.__new__(cls)
+        memo[id(self)] = result
+        for k, v in self.__dict__.items():
+            setattr(result, k, copy.deepcopy(v, memo))
+        return result
+
 
 def tensor(
     data: Union[list, np.ndarray] = None,