[Dy2Stat] Fix always copy by paddle.to_tensor from PR #33335(#33590)

python/paddle/fluid/dygraph/dygraph_to_static/partial_program.py

@@ -247,28 +247,27 @@ class PartialProgramLayer(layers.Layer):
         flatten_inputs = flatten(inputs)
         # Convert variable into VarBase and feed in training data.
         input_vars = []
+        expected_place = framework._current_expected_place()
         for i, value in enumerate(flatten_inputs):
             if isinstance(value, np.ndarray):
                 var = core.VarBase(
                     value=value,
                     name=self._inputs[i].desc.name(),
                     persistable=False,
-                    place=framework._current_expected_place(),
+                    place=expected_place,
                     zero_copy=True)
             elif isinstance(value, core.VarBase):
-                value.name = self._inputs[i].desc.name()
-                if value.stop_gradient:
-                    # NOTE(Aurelius84): If var is on CPUPlace, it will be transformed multi times
-                    # into CUDAPlace when it's as input of multi Ops. so we move it in advance
-                    # to avoid this problem.
-                    var = paddle.to_tensor(
-                        value,
-                        dtype=value.dtype,
-                        place=framework._current_expected_place(),
-                        stop_gradient=True)
+                # NOTE(Aurelius84): If var is on CPUPlace, it will be transformed multi times
+                # into CUDAPlace when it's as input of multi Ops. so we move it in advance
+                # to avoid this problem.
+                if value.stop_gradient and not value.place._equals(
+                        expected_place):
+                    var = value._copy_to(expected_place, False)
+                    var.stop_gradient = True
                     var.name = value.name
                 else:
                     var = value
+                var.name = self._inputs[i].desc.name()
             else:
                 continue
             input_vars.append(var)