chore: import upstream snapshot with attribution

paddle/phi/kernels/gpu/index_select_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/backends/gpu/gpu_info.h"
+#include "paddle/phi/backends/gpu/gpu_launch_config.h"
+#include "paddle/phi/backends/gpu/gpu_primitives.h"
+#include "paddle/phi/core/kernel_registry.h"
+#include "paddle/phi/core/utils/data_type.h"
+
+namespace phi {
+
+template <typename T, typename IndexT>
+__global__ void index_select_cuda_kernel(const T* input,
+                                         T* output,
+                                         const IndexT* index,
+                                         int64_t N,
+                                         int64_t stride,
+                                         int64_t size,
+                                         int64_t delta,
+                                         int64_t dim_size) {
+  CUDA_KERNEL_LOOP_TYPE(idx, N, int64_t) {
+    int64_t pre_idx = idx / (stride * size);
+    int64_t dim_idx = idx % (stride * size) / stride;
+    IndexT src_dim_idx = index[dim_idx];
+    if (src_dim_idx < 0) {
+      src_dim_idx += dim_size;
+    }
+    int64_t input_idx =
+        idx + (delta * pre_idx + src_dim_idx - dim_idx) * stride;
+    output[idx] = input[input_idx];
+  }
+}
+
+}  // namespace phi