Add the macro for NVCC (test=develop)

Author: yihuaxu

paddle/fluid/operators/stack_op.h

@@ -149,11 +149,20 @@ class StackKernel : public framework::OpKernel<T> {
     for (auto i = axis; i < dim.size(); ++i) post *= dim[i];
 
 #ifdef __NVCC__
+    int total_num = pre * n * post;
+    auto &dev_ctx = ctx.template device_context<DeviceContext>();
+
     thrust::device_vector<const T *> device_x_vec(x_datas);
     auto x_data_arr = device_x_vec.data().get();
+
+    StackFunctorForRange(dev_ctx, x_data_arr, y_data, total_num, n, post);
+
+    // Wait() must be called because device_x_vec may be destructed before
+    // kernel ends
+    dev_ctx.Wait();
 #else
     auto x_data_arr = x_datas.data();
-#endif
+
     size_t x_offset = 0;
     size_t y_offset = 0;
     for (int i = 0; i < pre; i++) {
@@ -164,10 +173,6 @@ class StackKernel : public framework::OpKernel<T> {
       }
       x_offset += post;
     }
-#ifdef __NVCC__
-    // Wait() must be called because device_x_vec may be destructed before
-    // kernel ends
-    dev_ctx.Wait();
 #endif
   }
 };