Implement details for d-expand

Fix a function call

onnxruntime/contrib_ops/cuda/collective/distributed_expand.cc

@@ -26,7 +26,47 @@ DistributedExpand<T>::DistributedExpand(const OpKernelInfo& info) : DistributedK
 template <typename T>
 Status DistributedExpand<T>::ComputeInternal(OpKernelContext* context) const {
   ORT_ENFORCE(context != nullptr);
-  return Status(common::ONNXRUNTIME, common::NOT_IMPLEMENTED, "Encounter unsupported expand pattern.");
+  // Assumptions.
+  //  - Shape is not sharded.
+  // Algorithm.
+  //  - Compute logical output shape.
+  //  - Compute local output shape.
+  //  - Expand from local input to local output.
+
+  auto input_tensor = context->Input<Tensor>(0);
+  auto shape_tensor = context->Input<Tensor>(1);
+  const auto& input_sharding_spec = input_shard_specs_.at(0);
+  const auto& shape_sharding_spec = input_shard_specs_.at(1);
+  const auto& output_sharding_spec = output_shard_specs_.at(0);
+
+  ORT_ENFORCE(shape_sharding_spec.HasNoShard(),
+              "It's not worth to shard Shape tensor. "
+              "If sharding shape is needed, please submit a feature request.");
+  // Compute logical input shape.
+  const auto original_input_shape = ComputeOriginShape(input_tensor->Shape(), input_sharding_spec);
+
+  // Compute logical output shape.
+  // This `shape_tensor` stores the logical output shape.
+  const auto* p_shape = shape_tensor->Data<int64_t>();
+  TensorShapeVector original_output_dims{p_shape, p_shape + shape_tensor->Shape().Size()};
+  TensorShape original_output_shape(original_output_dims);
+  ORT_ENFORCE(
+    onnxruntime::cuda::ComputeOutputShape(
+      Node().Name(),
+      original_input_shape,
+      original_output_dims, original_output_shape).IsOK());
+
+  // Compute local output shape.
+  const auto local_output_shape = ComputeShardShape(original_output_shape, output_sharding_spec);
+
+  auto output_tensor = context->Output(0, local_output_shape);
+
+  return FuncExpand(
+    this,
+    context,
+    input_tensor,
+    shape_tensor,
+    output_tensor);
 }
 
 ONNX_OPERATOR_TYPED_KERNEL_EX(