chore: import upstream snapshot with attribution

paddle/phi/kernels/impl/unbind_kernel_impl.h

@@ -0,0 +1,47 @@
+// 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/concat_and_split_functor.h"
+#include "paddle/phi/kernels/unbind_kernel.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void UnbindKernel(const Context& dev_ctx,
+                  const DenseTensor& x,
+                  int axis,
+                  std::vector<DenseTensor*> outs) {
+  int64_t unbind_numel = x.numel();
+  PADDLE_ENFORCE_LE(unbind_numel,
+                    std::numeric_limits<int>::max(),
+                    ::common::errors::PreconditionNotMet(
+                        "The number of proposals in unbind should be less than "
+                        "2^31, but got %lld. Please check the input tensor. ",
+                        unbind_numel));
+  auto x_dims = x.dims();
+  axis = axis < 0 ? x_dims.size() + axis : axis;
+
+  std::vector<const DenseTensor*> shape_refer;
+  for (size_t j = 0; j < outs.size(); ++j) {
+    dev_ctx.template Alloc<T>(outs[j]);
+    shape_refer.emplace_back(outs[j]);
+  }
+
+  funcs::SplitFunctor<Context, T> functor;
+  functor(dev_ctx, x, shape_refer, axis, &outs);
+}
+
+}  // namespace phi