chore: import upstream snapshot with attribution

paddle/phi/kernels/impl/angle_kernel_impl.h

@@ -0,0 +1,41 @@
+// 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/core/dense_tensor.h"
+#include "paddle/phi/kernels/funcs/complex_functors.h"
+#include "paddle/phi/kernels/funcs/for_range.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void AngleKernel(const Context& dev_ctx,
+                 const DenseTensor& x,
+                 DenseTensor* out) {
+  auto numel = x.numel();
+  auto* x_data = x.data<T>();
+  out->Resize(x.dims());
+  if (out->numel() == 0) {
+    dev_ctx.template Alloc<dtype::Real<T>>(out);
+    return;
+  }
+  auto* out_data = dev_ctx.template Alloc<dtype::Real<T>>(out);
+
+  funcs::ForRange<Context> for_range(dev_ctx, numel);
+  funcs::AngleFunctor<T> functor(x_data, out_data, numel);
+  for_range(functor);
+}
+
+}  // namespace phi