chore: import upstream snapshot with attribution

paddle/phi/kernels/impl/maxout_kernel_impl.h

@@ -0,0 +1,40 @@
+// 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.
+
+#pragma once
+
+#include "paddle/phi/kernels/funcs/maxouting.h"
+#include "paddle/phi/kernels/maxout_kernel.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void MaxOutKernel(const Context& dev_ctx,
+                  const DenseTensor& x,
+                  int groups,
+                  int axis,
+                  DenseTensor* out) {
+  if (out && out->numel() == 0) {
+    dev_ctx.template Alloc<T>(out);
+    return;
+  }
+  if (axis < 0) {
+    axis += x.dims().size();
+  }
+
+  funcs::MaxOutFunctor<Context, T> maxout_forward;
+  maxout_forward(dev_ctx, x, out, groups, axis);
+}
+
+}  // namespace phi