chore: import upstream snapshot with attribution

paddle/phi/kernels/cpu/gather_tree_kernel.cc

@@ -0,0 +1,84 @@
+// 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/gather_tree_kernel.h"
+
+#include "paddle/phi/core/enforce.h"
+#include "paddle/phi/core/kernel_registry.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void GatherTreeKernel(const Context &dev_ctx,
+                      const DenseTensor &ids,
+                      const DenseTensor &parents,
+                      DenseTensor *out) {
+  const auto *ids_data = ids.data<T>();
+  const auto *parents_data = parents.data<T>();
+
+  T *out_data = dev_ctx.template Alloc<T>(out);
+  if (out && out->numel() == 0) {
+    return;
+  }
+
+  auto &ids_dims = ids.dims();
+  int64_t max_length = ids_dims[0];
+  auto batch_size = ids_dims[1];
+  auto beam_size = ids_dims[2];
+
+  PADDLE_ENFORCE_NOT_NULL(ids_data,
+                          common::errors::InvalidArgument(
+                              "Input(Ids) of gather_tree should not be null."));
+
+  PADDLE_ENFORCE_NOT_NULL(
+      parents_data,
+      common::errors::InvalidArgument(
+          "Input(Parents) of gather_tree should not be null."));
+
+  for (int batch = 0; batch < batch_size; batch++) {
+    for (int beam = 0; beam < beam_size; beam++) {
+      auto idx =
+          (max_length - 1) * batch_size * beam_size + batch * beam_size + beam;
+      out_data[idx] = ids_data[idx];
+      auto parent = parents_data[idx];
+      for (int64_t step = max_length - 2; step >= 0; step--) {
+        PADDLE_ENFORCE_LT(
+            parent,
+            beam_size,
+            common::errors::InvalidArgument(
+                "The parents must be less than beam size, but received "
+                "parents %d is greater than or equal to beam size %d. ",
+                parent,
+                beam_size));
+
+        PADDLE_ENFORCE_GE(
+            parent,
+            0,
+            common::errors::InvalidArgument(
+                "The parents must be greater than or equal to 0, but received "
+                "parents %d is less than 0. ",
+                parent));
+
+        idx = step * batch_size * beam_size + batch * beam_size;
+        out_data[idx + beam] = ids_data[idx + parent];
+        parent = parents_data[idx + parent];
+      }
+    }
+  }
+}
+
+}  // namespace phi
+
+PD_REGISTER_KERNEL(
+    gather_tree, CPU, ALL_LAYOUT, phi::GatherTreeKernel, int, int64_t) {}