如何在Windows上的cuda推送调用中指定OpenMP执行策略？

在将代码从Linux移植到Windows时，感谢Visual Studio C ++ 2015社区，我遇到了一个我无法理解的编译错误。 下面是一个展示这个错误的示例程序，使用OpenMP构build一个双精度vector然后用cuda推力对它进行sorting。

# include <thrust/sort.h> # include <thrust/system/omp/execution_policy.h> # include <chrono> # include <random> # include <vector> double unit_random() { static std::default_random_engine generator(std::chrono::system_clock::Now().time_since_epoch().count()); static std::uniform_real_distribution<double> distribution(double(0),double(1)); return distribution(generator); } int main(int argc,char* argv[]) { constexpr size_t input_size = 100000; std::vector< double > input(input_size,0); for ( size_t i = 0; i < input_size; ++i) input[i] = unit_random() * 1000; thrust::sort(thrust::omp::par,input.begin(),input.end()); return 0; }

以下是在Visual Studio控制台中看到的错误（文件名被缩短）：

thrust/system/omp/detail/sort.inl(136): error C2146: Syntax error: missing ';' before identifier 'nseg' thrust/detail/sort.inl(83): note: see reference to function template instantiation 'void thrust::system::omp::detail::stable_sort<thrust::system::omp::detail::par_t,RandomAccessIterator,StrictWeakOrdering>(thrust::system::omp::detail::execution_policy<thrust::system::omp::detail::par_t> &,StrictWeakOrdering)' being compiled with [ RandomAccessIterator=std::_Vector_iterator<std::_Vector_val<std::_Simple_types<double>>>,StrictWeakOrdering=thrust::less<value_type> ] thrust/system/detail/generic/sort.inl(63): note: see reference to function template instantiation 'void thrust::stable_sort<DerivedPolicy,StrictWeakOrdering>(const thrust::detail::execution_policy_base<DerivedPolicy> &,StrictWeakOrdering)' being compiled with [ DerivedPolicy=thrust::system::omp::detail::par_t,RandomAccessIterator=std::_Vector_iterator<std::_Vector_val<std::_Simple_types<double>>>,StrictWeakOrdering=thrust::less<value_type> ] thrust/detail/sort.inl(56): note: see reference to function template instantiation 'void thrust::system::detail::generic::sort<Derived,StrictWeakOrdering>(thrust::execution_policy<Derived> &,StrictWeakOrdering)' being compiled with [ Derived=thrust::system::omp::detail::par_t,StrictWeakOrdering=thrust::less<value_type> ] thrust/system/detail/generic/sort.inl(49): note: see reference to function template instantiation 'void thrust::sort<DerivedPolicy,thrust::less<value_type>>(const thrust::detail::execution_policy_base<DerivedPolicy> &,StrictWeakOrdering=thrust::less<value_type> ] thrust/detail/sort.inl(41): note: see reference to function template instantiation 'void thrust::system::detail::generic::sort<Derived,RandomAccessIterator>(thrust::execution_policy<Derived> &,RandomAccessIterator)' being compiled with [ Derived=thrust::system::omp::detail::par_t,RandomAccessIterator=std::_Vector_iterator<std::_Vector_val<std::_Simple_types<double>>> ] windows_cuda_thrust_error.cc(24): note: see reference to function template instantiation 'void thrust::sort<DerivedPolicy,std::_Vector_iterator<std::_Vector_val<std::_Simple_types<double>>>>(const thrust::detail::execution_policy_base<DerivedPolicy> &,RandomAccessIterator)' being compiled with [ DerivedPolicy=thrust::system::omp::detail::par_t,RandomAccessIterator=std::_Vector_iterator<std::_Vector_val<std::_Simple_types<double>>> ] thrust/system/omp/detail/sort.inl(136): error C2275: 'IndexType': illegal use of this type as an expression thrust/system/omp/detail/sort.inl(113): note: see declaration of 'IndexType' thrust/system/omp/detail/sort.inl(136): error C2065: 'nseg': undeclared identifier thrust/system/omp/detail/sort.inl(142): error C2065: 'nseg': undeclared identifier thrust/system/omp/detail/sort.inl(159): error C2065: 'nseg': undeclared identifier ========== Build: 0 succeeded,1 Failed,1 up-to-date,0 skipped ==========

相同的代码在Linux上正常工作。

我们应该如何在Windows上的cuda推送调用中指定OpenMP执行策略？ 或者，我在这个特定的环境中做错了什么？

CUDA C诉Thrust，我错过了什么？

使用的推力版本是1.8.1，这里是推力函数的摘录，在文件thrust / system / omp / detail / sort.inl中，提高了编译错误：

template<typename DerivedPolicy,typename RandomAccessIterator,typename StrictWeakOrdering> void stable_sort(execution_policy<DerivedPolicy> &exec,RandomAccessIterator first,RandomAccessIterator last,StrictWeakOrdering comp) { // ... typedef typename thrust::iterator_difference<RandomAccessIterator>::type IndexType; if(first == last) return; #pragma omp parallel { thrust::system::detail::internal::uniform_decomposition<IndexType> decomp(last - first,1,omp_get_num_threads()); // process id IndexType p_i = omp_get_thread_num(); // every thread sorts its own tile if(p_i < decomp.size()) { thrust::stable_sort(thrust::seq,first + decomp[p_i].begin(),first + decomp[p_i].end(),comp); } #pragma omp barrier IndexType nseg = decomp.size(); // line 136 // ... } }

正如@ kangshiyin所建议的那样，我在github上提出了一个问题（见问题＃817 ），并且推动开发人员找到了解决方法。 问题来自MSVC当前处理OpenMP代码的方式，因此问题中提供的代码非常好。

如果出现类似的问题，请先尝试更新到推力的最新版本。 您也可以尝试应用相同的解决方法：只需在引起错误的行之前添加一个分号。