没有SYCL_EXTERNAL属性，SYCL内核无法调用未定义的函数

Question

我试图计算KNN的欧几里德距离，但同时使用dpc++。训练数据集包含5个特征和1600行，而我希望并行计算当前测试点与网格上每个训练点之间的距离，但我始终得到有关sycl内核的错误。该功能的代码：

code

std::vector<double> distance_calculation_FPGA(queue& q,const std::vector<std::vector<double>>& dataset,const std::vector<double>& curr_test) {
range<1> num_items{ dataset.size()};
std::vector<double>res;


res.resize(dataset.size());
buffer dataset_buf(dataset);
buffer curr_test_buf(curr_test);
buffer res_buf(res.data(), num_items);

q.submit([&](handler& h) {
    accessor a(dataset_buf, h, read_only);
    accessor b(curr_test_buf, h, read_only);

    accessor dif(res_buf, h, write_only, no_init);

   h.parallel_for(num_items, [=](auto i) {
  
        for (int j = 0; j <(const int) a[i].size(); ++j) {
            dif[i] += (a[i][j] - b[j]) * (a[i][j] - b[j]) ;
        }
        });
 });
for (int i = 0; i < res.size(); ++i) {
    std::cout << res[i] << std::endl;
} 
//old distance calculation (serial)
//for (int i = 0; i < dataset.size(); ++i) {
 //   double dis = 0;
   // for (int j = 0; j < dataset[i].size(); ++j) {
     //   dis += (curr_test[j] - dataset[i][j]) * (curr_test[j] - dataset[i][j]);
    //}
    //res.push_back(dis);
//}

return res;

}

我所收到的错误：

SYCL kernel cannot call a variadic function

SYCL kernel cannot call an undefined function without SYCL_EXTERNAL attribute

会非常感谢你的帮助！

谢谢

Answer 1

我们尝试通过创建虚拟的'dataset‘和'curr_test’变量来运行您的代码。我们成功地运行了这个程序。请参阅这条线

请参阅下面所附的完整代码。

#include <CL/sycl.hpp>
#include <iostream> 
using namespace sycl;

std::vector<double> distance_calculation_FPGA(queue& q,const std::vector<std::vector<double>>& dataset,const std::vector<double>& curr_test) 
{
range<1> num_items{ dataset.size()};
std::vector<double>res;

res.resize(dataset.size());
buffer dataset_buf(dataset);
buffer curr_test_buf(curr_test);
buffer res_buf(res.data(), num_items);

q.submit([&](handler& h) {
accessor a(dataset_buf, h, read_only);
accessor b(curr_test_buf, h, read_only);

accessor dif(res_buf, h, write_only, no_init);

h.parallel_for(num_items, [=](auto i) {

    for (int j = 0; j <(const int) a[i].size(); ++j) {
//           dif[i] += (a[i][j] - b[j]) * (a[i][j] - b[j]) ;
         dif[i]+=a[i][j];          
        }
        });
    });
    q.wait(); //We have added this line of code for synchronization.
    for (int i : res) { 
        std::cout <<i<< std::endl;
    } 
    return res;
    }


int main(){
std::vector<std::vector<double>> dataset;
for(int i=0;i<5;i++)
{
    std::vector<double> d;

    for(int j=0;j<1600;j++)
    {
        d.push_back((double)j);
    }
    dataset.push_back(d);
}

std::vector<double> curr_test;
for(int i=0;i<1600;i++)
{
    curr_test.push_back((double)i);
}
queue q;
std::cout << "Running on "<< 
q.get_device().get_info<sycl::info::device::name>()<< std::endl; 
//print the device name as a test to check the parallelisation

distance_calculation_FPGA(q,dataset,curr_test);

return 0;
}