chore: import upstream snapshot with attribution

paddle/phi/kernels/custom/c_allreduce_max_kernel.cc

@@ -0,0 +1,38 @@
+/* Copyright (c) 2025 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/custom/c_allreduce_kernel_impl.h"
+#ifdef PADDLE_WITH_CUSTOM_DEVICE
+namespace phi {
+template <typename T, typename Context>
+void CAllReduceMaxKernel(const Context& dev_ctx,
+                         const DenseTensor& x_in,
+                         int ring_id,
+                         bool use_calc_stream,
+                         bool use_model_parallel,
+                         DenseTensor* out) {
+  CAllReduceKernel<T, Context, phi::ccl::CCLReduceOp::MAX>(
+      dev_ctx, x_in, ring_id, use_calc_stream, use_model_parallel, out);
+}
+}  // namespace phi
+
+PD_REGISTER_KERNEL(c_allreduce_max,
+                   Custom,
+                   ALL_LAYOUT,
+                   phi::CAllReduceMaxKernel,
+                   float,
+                   double,
+                   int32_t,
+                   int64_t,
+                   phi::float16) {}
+#endif