support convert core.Tensor to paddle.Tensor (#33430)

paddle/fluid/pybind/imperative.cc

@@ -245,7 +245,7 @@ static void InitVarBaseFromNumpyWithArgDefault(imperative::VarBase *self,
 }
 
 static void InitVarBaseFromTensorWithArgDefault(
-    imperative::VarBase *self, const framework::LoDTensor &tensor) {
+    imperative::VarBase *self, const framework::Tensor &tensor) {
   VLOG(4) << "Init VarBase";
   auto place = imperative::GetCurrentTracer()->ExpectedPlace();
   new (self) imperative::VarBase(

python/paddle/fluid/tests/unittests/test_var_base.py

@@ -176,7 +176,6 @@ class TestVarBase(unittest.TestCase):
 
                 x = paddle.to_tensor(1, dtype='uint8')
                 self.assertEqual(x.item(), 1)
-                print(type(x.item()))
                 self.assertTrue(isinstance(x.item(), int))
 
                 x = paddle.to_tensor(1, dtype='int8')
@@ -203,6 +202,24 @@ class TestVarBase(unittest.TestCase):
                 self.assertEqual(x.item(), 1 + 1j)
                 self.assertTrue(isinstance(x.item(), complex))
 
+                numpy_array = np.random.randn(3, 4)
+                # covert core.LoDTensor to paddle.Tensor
+                lod_tensor = paddle.fluid.core.LoDTensor()
+                place = paddle.fluid.framework._current_expected_place()
+                lod_tensor.set(numpy_array, place)
+                x = paddle.to_tensor(lod_tensor)
+                self.assertTrue(np.array_equal(x.numpy(), numpy_array))
+                self.assertEqual(x.type, core.VarDesc.VarType.LOD_TENSOR)
+                self.assertEqual(str(x.place), str(place))
+
+                # covert core.Tensor to paddle.Tensor
+                x = paddle.to_tensor(numpy_array)
+                dlpack = x.value().get_tensor()._to_dlpack()
+                tensor_from_dlpack = paddle.fluid.core.from_dlpack(dlpack)
+                x = paddle.to_tensor(tensor_from_dlpack)
+                self.assertTrue(np.array_equal(x.numpy(), numpy_array))
+                self.assertEqual(x.type, core.VarDesc.VarType.LOD_TENSOR)
+
                 with self.assertRaises(ValueError):
                     paddle.randn([3, 2, 2]).item()
                 with self.assertRaises(ValueError):

python/paddle/tensor/creation.py

@@ -136,9 +136,10 @@ def to_tensor(data, dtype=None, place=None, stop_gradient=True):
             data = data._copy_to(place, False)
             ata = _handle_dtype(data, dtype)
             data.stop_gradient = stop_gradient
-        elif isinstance(data, core.LoDTensor):
-            # convert LoDTensor to VarBase first
-            # Currenly, LoDTensor does no copy when places are same
+        elif isinstance(data, (core.LoDTensor, core.Tensor)):
+            # Note(zhouwei25): should't expose it to users, just for internal use.
+            # convert core.Tensor/core.LoDTensor to VarBase first
+            # Currenly, there is no copy when places are same
             data = paddle.Tensor(data)
             if not data.place._equals(place):
                 data = data._copy_to(place, False)