chore: import upstream snapshot with attribution

paddle/phi/kernels/cpu/i0e_grad_kernel.cc

@@ -0,0 +1,49 @@
+// Copyright (c) 2023 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "paddle/phi/kernels/i0e_grad_kernel.h"
+
+#include "paddle/phi/backends/cpu/cpu_context.h"
+#include "paddle/phi/core/kernel_registry.h"
+#include "paddle/phi/kernels/funcs/for_range.h"
+#include "paddle/phi/kernels/impl/bessel_grad_kernel_impl.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void I0eGradKernel(const Context& dev_ctx,
+                   const DenseTensor& x,
+                   const DenseTensor& out,
+                   const DenseTensor& out_grad,
+                   DenseTensor* x_grad) {
+  if (x_grad && x_grad->numel() == 0) {
+    dev_ctx.template Alloc<T>(x_grad);
+    return;
+  }
+
+  auto size = x.numel();
+  auto* x_data = x.data<T>();
+  auto* out_data = out.data<T>();
+  auto* out_grad_data = out_grad.data<T>();
+  auto* x_grad_data = dev_ctx.template Alloc<T>(x_grad);
+
+  funcs::ForRange<Context> for_range(dev_ctx, size);
+  I0eGradFunctor<T> functor(x_data, out_data, out_grad_data, x_grad_data, size);
+  for_range(functor);
+}
+
+}  // namespace phi
+
+PD_REGISTER_KERNEL(
+    i0e_grad, CPU, ALL_LAYOUT, phi::I0eGradKernel, float, double) {}