Use variable_data() in tensor_to_numpy (#22214)

Summary:
As part of the Variable/Tensor merge, we want to gradually remove call sites of `tensor_data()` and the API itself, and instead uses `variable_data()`. This PR removes the `tensor_data()` call in the tensor_to_numpy conversion path.
Pull Request resolved: #22214

Differential Revision: D15997397

Pulled By: yf225

fbshipit-source-id: 6fcab7b14e138824fc2adb5434512bcf868ca375

tools/autograd/templates/python_variable_methods.cpp

@@ -428,12 +428,7 @@ static PyObject * THPVariable_numpy(PyObject* self, PyObject* arg)
   HANDLE_TH_ERRORS
   jit::tracer::warn("Converting a tensor to a NumPy array", jit::tracer::WARN_PYTHON_DATAFLOW);
   auto& self_ = reinterpret_cast<THPVariable*>(self)->cdata;
-  if (self_.requires_grad()) {
-    throw std::runtime_error(
-        "Can't call numpy() on Variable that requires grad. "
-        "Use var.detach().numpy() instead.");
-  }
-  return torch::utils::tensor_to_numpy(self_.tensor_data());
+  return torch::utils::tensor_to_numpy(self_);
   END_HANDLE_TH_ERRORS
 }
 

torch/csrc/utils/tensor_numpy.cpp

@@ -85,6 +85,11 @@ PyObject* tensor_to_numpy(const at::Tensor& tensor) {
   if (tensor.type().backend() != Backend::CPU) {
     throw TypeError("NumPy conversion for %s is not supported", tensor.type().toString().c_str());
   }
+  if (tensor.requires_grad()) {
+    throw std::runtime_error(
+        "Can't call numpy() on Variable that requires grad. "
+        "Use var.detach().numpy() instead.");
+  }
   auto dtype = aten_to_numpy_dtype(tensor.scalar_type());
   auto sizes = to_numpy_shape(tensor.sizes());
   auto strides = to_numpy_shape(tensor.strides());
@@ -110,7 +115,8 @@ PyObject* tensor_to_numpy(const at::Tensor& tensor) {
   // object of the ndarray to the tensor and disabling resizes on the storage.
   // This is not sufficient. For example, the tensor's storage may be changed
   // via Tensor.set_, which can free the underlying memory.
-  PyObject* py_tensor = THPVariable_Wrap(make_variable(tensor, false));
+  TORCH_INTERNAL_ASSERT(tensor.is_variable());
+  PyObject* py_tensor = THPVariable_Wrap(tensor);
   if (!py_tensor) throw python_error();
   if (PyArray_SetBaseObject((PyArrayObject*)array.get(), py_tensor) == -1) {
     return nullptr;