chore: import upstream snapshot with attribution

paddle/phi/kernels/cpu/label_smooth_kernel.cc

@@ -0,0 +1,53 @@
+// Copyright (c) 2022 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/label_smooth_kernel.h"
+
+#include "paddle/phi/backends/cpu/cpu_context.h"
+#include "paddle/phi/core/kernel_registry.h"
+#include "paddle/phi/kernels/funcs/eigen/common.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void LabelSmoothKernel(const Context& dev_ctx,
+                       const DenseTensor& label,
+                       const optional<DenseTensor>& prior_dist,
+                       float epsilon,
+                       DenseTensor* out) {
+  auto label_dim = label.dims()[label.dims().size() - 1];
+  dev_ctx.template Alloc<T>(out);
+  auto& dev = *dev_ctx.eigen_device();
+  if (label_dim != 0) {
+    auto eigen_out = EigenVector<T>::Flatten(*out);
+    auto eigen_in = EigenVector<T>::Flatten(label);
+    if (prior_dist.is_initialized()) {
+      auto dist = EigenVector<T>::Flatten(*prior_dist.get_ptr());
+      eigen_out.device(dev) =
+          static_cast<T>(1 - epsilon) * eigen_in +
+          static_cast<T>(epsilon) *
+              dist.broadcast(Eigen::DSizes<int, 1>(
+                  static_cast<int>(label.numel() / label_dim)));
+    } else {
+      eigen_out.device(dev) =
+          static_cast<T>(1 - epsilon) * eigen_in +
+          static_cast<T>(epsilon / static_cast<float>(label_dim));
+    }
+  }
+}
+
+}  // namespace phi
+
+PD_REGISTER_KERNEL(
+    label_smooth, CPU, ALL_LAYOUT, phi::LabelSmoothKernel, float, double) {}