chore: import upstream snapshot with attribution

paddle/phi/kernels/gpu/c_scatter_kernel.cu

@@ -0,0 +1,125 @@
+// Copyright (c) 2024 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/gpu/c_scatter_kernel.h"
+#include "glog/logging.h"
+#include "paddle/phi/core/distributed/comm_context_manager.h"
+
+#if defined(PADDLE_WITH_NCCL) || defined(PADDLE_WITH_RCCL)
+#include "paddle/phi/core/distributed/nccl_comm_context.h"
+#endif
+#include "paddle/phi/core/dense_tensor.h"
+#include "paddle/phi/core/kernel_registry.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void CScatterOpCUDAKernel(const Context& dev_ctx,
+                          const DenseTensor& input,
+                          int ring_id,
+                          int root,
+                          int nranks,
+                          bool use_calc_stream,
+                          DenseTensor* out) {
+#if defined(PADDLE_WITH_NCCL) || defined(PADDLE_WITH_RCCL)
+  auto x = &input;
+  int64_t numel = x->numel();
+  ncclDataType_t dtype = ToNCCLDataType(x->dtype());
+
+  int root_id = root;
+  auto place = dev_ctx.GetPlace();
+  gpuStream_t stream = nullptr;
+  distributed::NCCLCommContext* comm_ctx = nullptr;
+  PADDLE_ENFORCE_GE(
+      root_id,
+      0,
+      common::errors::InvalidArgument(
+          "The root_id (%d) for c_scatter_op must be non-negative.", root_id));
+  PADDLE_ENFORCE_GE(
+      ring_id,
+      0,
+      common::errors::InvalidArgument(
+          "The ring_id (%d) for c_scatter_op must be non-negative.", ring_id));
+
+  comm_ctx =
+      static_cast<distributed::NCCLCommContext*>(dev_ctx.GetCommContext());
+  PADDLE_ENFORCE_NE(comm_ctx,
+                    nullptr,
+                    common::errors::Unavailable(
+                        "NCCLCommContext is nullptr, collective op should "
+                        "has ring_id attr."));
+  PADDLE_ENFORCE_EQ(nranks,
+                    comm_ctx->GetSize(),
+                    common::errors::InvalidArgument(
+                        "The number of ranks (%d) you set of must "
+                        "be equal to comm_ctx->GetSize() (%d).",
+                        nranks,
+                        comm_ctx->GetSize()));
+
+  stream = comm_ctx->GetStream();
+  VLOG(3) << "new comm_context_manager has ring_id " << ring_id;
+
+  if (use_calc_stream) {
+    // should ExecutionContext for calc stream.
+    stream = dev_ctx.stream();
+  }
+
+  DDim x_dims = x->dims();
+  DDim out_dims(x_dims);
+  DenseTensor temp;
+  temp.Resize(out_dims);
+  auto out_ptr = dev_ctx.template Alloc<T>(&temp);
+
+  if (root_id == comm_ctx->GetRank()) {
+    comm_ctx->Broadcast(const_cast<DenseTensor*>(x), *x, root_id, stream);
+    Copy(dev_ctx,
+         *static_cast<const DenseTensor*>(x),
+         place,
+         false,
+         static_cast<DenseTensor*>(&temp));
+  } else {
+    comm_ctx->Broadcast(&temp, temp, root_id, stream);
+  }
+
+  out_dims[0] = out_dims[0] / nranks;
+  auto start_index = out_dims[0] * comm_ctx->GetRank();
+  auto end_index = start_index + out_dims[0];
+  temp = temp.Slice(start_index, end_index);
+  temp.Resize(out_dims);
+  out->Resize(out_dims);
+  dev_ctx.template Alloc<T>(out);
+  Copy(dev_ctx,
+       *static_cast<const DenseTensor*>(&temp),
+       place,
+       true,
+       static_cast<DenseTensor*>(out));
+  out->Resize(out_dims);
+#else
+  PADDLE_ENFORCE_EQ(
+      true,
+      false,
+      common::errors::Unavailable("PaddlePaddle should compile with GPU."));
+#endif
+}
+}  // namespace phi
+
+PD_REGISTER_KERNEL(c_scatter,
+                   GPU,
+                   ALL_LAYOUT,
+                   phi::CScatterOpCUDAKernel,
+                   float,
+                   double,
+                   int,
+                   int64_t,
+                   phi::float16) {}