static PyObject *unpack_saved_variables(
THPFunction *self,
std::function<PyObject*(const Variable&)> unpack_fn)
{
THPUtils_assert(!self->has_freed_buffers, ERR_BACKWARD_TWICE);
auto& saved_variables = self->saved_variables;
if (saved_variables.empty())
return PyTuple_New(0);
int num_saved = saved_variables.size();
THPObjectPtr saved(PyTuple_New(num_saved));
if (!saved)
return NULL;
auto saved_for = THPFunction_asFunction(self);
for (int i = 0; i < num_saved; i++) {
auto unpacked_var = saved_variables[i].unpack(saved_for);
THPObjectPtr value;
if (!unpacked_var.defined()) {
Py_INCREF(Py_None);
value = Py_None;
} else {
value = unpack_fn(unpacked_var);
}
PyTuple_SET_ITEM(saved.get(), i, value.release());
}
return saved.release();
}
PyObject *THPFunction_apply(PyObject *cls, PyObject *inputs)
{
HANDLE_TH_ERRORS
torch::autograd::profiler::RecordFunction record(((PyTypeObject*)cls)->tp_name);
THPObjectPtr backward_cls(PyObject_GetAttrString(cls, "_backward_cls"));
if (!backward_cls) return NULL;
THPObjectPtr ctx_obj(PyObject_CallFunctionObjArgs(backward_cls, NULL));
if (!ctx_obj) return NULL;
THPFunction* ctx = (THPFunction*)ctx_obj.get();
// Prepare inputs and allocate context (grad fn)
auto info_pair = unpack_input<false>(inputs);
UnpackedInput& unpacked_input = info_pair.first;
InputFlags& input_info = info_pair.second;
// Initialize backward function (and ctx)
bool is_volatile = input_info.flags.is_volatile;
ctx->cdata.set_flags(std::move(input_info.flags));
ctx->needs_input_grad = input_info.needs_input_grad.release();
ctx->is_variable_input = std::move(input_info.is_variable_input);
// Prepend ctx to tensor_input, in preparation for static method call
auto num_args = PyTuple_GET_SIZE(inputs);
THPObjectPtr ctx_tensor_input(PyTuple_New(num_args + 1));
PyTuple_SET_ITEM(ctx_tensor_input.get(), 0, ctx_obj.release());
for (int i = 0; i < num_args; ++i) {
PyObject *arg = PyTuple_GET_ITEM(unpacked_input.tensor_input.get(), i);
Py_INCREF(arg);
PyTuple_SET_ITEM(ctx_tensor_input.get(), i + 1, arg);
}
// Call forward
THPObjectPtr forward_fn(PyObject_GetAttrString(cls, "forward"));
if (!forward_fn) return NULL;
THPObjectPtr tensor_outputs(PyObject_CallObject(forward_fn, ctx_tensor_input));
if (!tensor_outputs) return NULL;
THPObjectPtr outputs {process_outputs(cls, ctx, unpacked_input, inputs,
std::move(tensor_outputs), is_volatile)};
return outputs.release();
END_HANDLE_TH_ERRORS
}