Add aten::_thnn_fused_gru_cell and _thnn_fused_lstm_cell (#926)

- [x] thnn_fused_gru_cell_forward
- [x] thnn_fused_gru_cell_backward
- [x] thnn_fused_lstm_cell_forward
- [x] thnn_fused_lstm_cell_backward

---------

Co-authored-by: Yutao Xu <[email protected]>

src/ATen/native/xpu/RNN.cpp

@@ -0,0 +1,46 @@
+#include <ATen/ATen.h>
+#include <ATen/native/xpu/sycl/RNNKernels.h>
+
+namespace at::native {
+
+std::tuple<Tensor, Tensor, Tensor> _thnn_fused_lstm_cell_xpu(
+    const Tensor& input_gates,
+    const Tensor& hidden_gates,
+    const Tensor& cx,
+    const std::optional<Tensor>& input_bias_opt,
+    const std::optional<Tensor>& hidden_bias_opt) {
+  return native::xpu::_thnn_fused_lstm_cell_kernel(
+      input_gates, hidden_gates, cx, input_bias_opt, hidden_bias_opt);
+}
+
+std::tuple<Tensor, Tensor, Tensor> _thnn_fused_lstm_cell_backward_xpu(
+    const std::optional<Tensor>& grad_hy_opt,
+    const std::optional<Tensor>& grad_cy_opt,
+    const Tensor& cx,
+    const Tensor& cy,
+    const Tensor& workspace,
+    bool has_bias) {
+  return native::xpu::_thnn_fused_lstm_cell_backward_kernel(
+      grad_hy_opt, grad_cy_opt, cx, cy, workspace, has_bias);
+}
+
+std::tuple<at::Tensor, at::Tensor> _thnn_fused_gru_cell_xpu(
+    const Tensor& input_gates,
+    const Tensor& hidden_gates,
+    const Tensor& hx,
+    const std::optional<at::Tensor>& input_bias,
+    const std::optional<at::Tensor>& hidden_bias) {
+  return native::xpu::_thnn_fused_gru_cell_kernel(
+      input_gates, hidden_gates, hx, input_bias, hidden_bias);
+}
+
+std::tuple<Tensor, Tensor, Tensor, Tensor, Tensor>
+_thnn_fused_gru_cell_backward_xpu(
+    const Tensor& grad_hy,
+    const Tensor& workspace,
+    bool has_bias) {
+  return native::xpu::_thnn_fused_gru_cell_backward_kernel(
+      grad_hy, workspace, has_bias);
+}
+
+} // namespace at::native

src/ATen/native/xpu/XPUFallback.template

@@ -186,7 +186,6 @@ TORCH_LIBRARY_IMPL(aten, XPU, m) {
     "ormqr",
     "_scaled_dot_product_efficient_attention",
     "_scaled_mm",
-    "_thnn_fused_gru_cell",
     "_to_sparse_csr",
     "triangular_solve.X",
     "_upsample_bilinear2d_aa.out",