chore: import upstream snapshot with attribution

paddle/phi/kernels/cast_kernel.h

@@ -0,0 +1,44 @@
+/* Copyright (c) 2021 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/empty_kernel.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void CastKernel(const Context& dev_ctx,
+                const DenseTensor& x,
+                DataType out_dtype,
+                DenseTensor* out);
+
+template <typename T, typename Context>
+DenseTensor Cast(const Context& dev_ctx,
+                 const DenseTensor& x,
+                 DataType out_dtype) {
+  DenseTensor dense_out;
+  MetaTensor meta_out(&dense_out);
+  CastInferMeta(x, out_dtype, &meta_out);
+  CastKernel<T, Context>(dev_ctx, x, out_dtype, &dense_out);
+  return dense_out;
+}
+
+#ifdef _WIN32
+#define INSTANTIATE_CAST_KERNEL(type, context)        \
+  template PADDLE_API void CastKernel<type, context>( \
+      const context&, const DenseTensor&, DataType, DenseTensor*);
+#endif
+}  // namespace phi