chore: import upstream snapshot with attribution

paddle/phi/kernels/impl/segment_pool_grad_kernel_impl.h

@@ -0,0 +1,55 @@
+// 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 <string>
+
+#include "paddle/phi/common/place.h"
+#include "paddle/phi/kernels/funcs/math_function.h"
+#include "paddle/phi/kernels/funcs/segment_pooling.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void SegmentPoolGradKernel(const Context& dev_ctx,
+                           const DenseTensor& x,
+                           const DenseTensor& segment_ids,
+                           const DenseTensor& out,
+                           const optional<DenseTensor>& summed_ids,
+                           const DenseTensor& out_grad,
+                           const std::string& pooltype,
+                           DenseTensor* x_grad) {
+  dev_ctx.template Alloc<T>(x_grad);
+  funcs::SetConstant<Context, T> set_zero;
+  set_zero(dev_ctx, x_grad, static_cast<T>(0));
+  // return after allocation if x_grad is empty.
+  if (x_grad && x_grad->numel() == 0) {
+    return;
+  }
+
+  auto index_type = segment_ids.type();
+  if (index_type == DataType::INT32) {
+    funcs::SegmentPoolGradFunctor<Context, T, int> pool;
+    pool(dev_ctx, x, out, out_grad, segment_ids, x_grad, summed_ids, pooltype);
+  } else if (index_type == DataType::INT64) {
+    funcs::SegmentPoolGradFunctor<Context, T, int64_t> pool;
+    pool(dev_ctx, x, out, out_grad, segment_ids, x_grad, summed_ids, pooltype);
+  } else {
+    PADDLE_THROW(common::errors::InvalidArgument(
+        "Unsupported index type, Expected int, int64, but got %s.",
+        index_type));
+  }
+}
+}  // namespace phi