chore: import upstream snapshot with attribution

paddle/phi/kernels/cpu/gather_kernel.cc

@@ -0,0 +1,82 @@
+// 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_kernel.h"
+
+#include "paddle/phi/core/kernel_registry.h"
+#include "paddle/phi/kernels/funcs/gather.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void GatherKernel(const Context& dev_ctx,
+                  const DenseTensor& x,
+                  const DenseTensor& index,
+                  const Scalar& axis,
+                  DenseTensor* out) {
+  if (out && out->numel() == 0) {
+    dev_ctx.template Alloc<T>(out);
+    return;
+  }
+  const auto& index_type = index.dtype();
+  auto axis_v = axis.to<int>();
+  if (axis_v < 0) {
+    axis_v += static_cast<int>(x.dims().size());
+  }
+
+  // gather at non-zero axis
+  if (axis_v != 0) {
+    if (index_type == DataType::INT32) {
+      funcs::GatherV2Function<T, int32_t>(dev_ctx, &x, &index, axis_v, out);
+    } else if (index_type == DataType::INT64) {
+      funcs::GatherV2Function<T, int64_t>(dev_ctx, &x, &index, axis_v, out);
+    }
+    return;
+  }
+
+  dev_ctx.template Alloc<T>(out);
+
+  if (x.numel() == 0) {
+    return;
+  }
+
+  // gather at axis 0
+  if (index_type == DataType::INT32) {
+    funcs::CPUGather<T, int>(dev_ctx, x, index, out);
+  } else if (index_type == DataType::INT64) {
+    funcs::CPUGather<T, int64_t>(dev_ctx, x, index, out);
+  } else {
+    PADDLE_THROW(common::errors::InvalidArgument(
+        "The data type of Input(Index) of gather "
+        "must be int32 or int64 on CPU."));
+  }
+}
+
+}  // namespace phi
+
+PD_REGISTER_KERNEL(gather,
+                   CPU,
+                   ALL_LAYOUT,
+                   phi::GatherKernel,
+                   float,
+                   double,
+                   uint8_t,
+                   int8_t,
+                   int16_t,
+                   int32_t,
+                   int64_t,
+                   bool,
+                   phi::bfloat16,
+                   phi::complex64,
+                   phi::complex128) {}