[英]How to thrust::make_transform_iterator that dereferences a device_ptr?
C ++和CUDA的新功能。 使用MSVS 2015社區和CUDA 9.2。
我嘗試制作一個transform_iterator,它僅取消引用device_ptr。
我收到編譯錯誤:函數“ dereference_device_double_functor :: operator()”無法通過給定的參數列表調用
我還制作了一個使用host_vector和普通雙指針的版本,以確保我的函子用法正確。
#include <iostream>
#include "thrust\device_vector.h"
#include "thrust\host_vector.h"
struct dereference_device_double_functor
{
dereference_device_double_functor() {}
typedef thrust::device_reference<thrust::device_ptr<double>> argument_type;
typedef double result_type;
__host__ __device__
double operator()(thrust::device_reference<thrust::device_ptr<double>> xDpRef) const {
thrust::device_ptr<double> xDp = (thrust::device_ptr<double>)xDpRef;
return *xDp;
}
};
struct dereference_host_double_functor
{
dereference_host_double_functor() {}
typedef double* argument_type;
typedef double result_type;
__host__ __device__
double operator()(double* const& xPtr) const {
return *xPtr;
}
};
int main()
{
// Create double
thrust::device_vector<double> dv(1, 5);
thrust::host_vector<double> hv(1, 6);
// Make sure its there
std::cout << dv[0] << std::endl;
std::cout << hv[0] << std::endl;
// Create pointers to doubles
thrust::device_vector<thrust::device_ptr<double>> dvPtr(1);
thrust::device_vector<double*> hvPtr(1);
// Assign pointers to doubles
dvPtr[0] = &(dv[0]);
hvPtr[0] = &(hv[0]);
// Make sure pointers point correctly
std::cout << *((thrust::device_ptr<double>)dvPtr[0]) << std::endl;
std::cout << *(hvPtr[0]) << std::endl;
// Test functor with iterator
auto dvi = dvPtr.begin();
double dvd = dereference_device_double_functor()(*dvi);
auto hvi = hvPtr.begin();
double hvd = dereference_host_double_functor()(*hvi);
// Make sure it worked with iterator
std::cout << dvd << std::endl;
std::cout << hvd << std::endl;
// Make dereferencing transfom iterators
auto tik = thrust::make_transform_iterator(dvPtr.begin(), dereference_device_double_functor());
auto tij = thrust::make_transform_iterator(hvPtr.begin(), dereference_host_double_functor());
// Check that transform iterators work
//std::cout << *tik << std::endl; // Will cause compile error: function "dereference_device_double_functor::operator()" cannot be called with the given argument list
std::cout << *tij << std::endl;
return 0;
}
感謝你的幫助!
在您的問題中,您聲明以下內容:
我嘗試制作一個transform_iterator,它僅取消引用device_ptr。
但是,這不是我在您的代碼中看到的:
__host__ __device__
double operator()(thrust::device_reference<thrust::device_ptr<double>> xDpRef) const {
當我在linux上編譯您的代碼時,我得到以下內容(摘自編譯錯誤提示):
$ nvcc -std=c++11 -o t351 t351.cu
/usr/local/cuda/bin/..//include/thrust/iterator/transform_iterator.h(312): error: function "dereference_device_double_functor::operator()" cannot be called with the given argument list
argument types are: (thrust::device_ptr<double>)
object type is: dereference_device_double_functor
...
因此推力為您傳遞了一個thrust::device_ptr<double>
。 但是您的函子運算符已配置為采用thrust::device_reference<thrust::device_ptr<double>>
當我從中修改您的代碼時:
__host__ __device__
double operator()(thrust::device_reference<thrust::device_ptr<double>> xDpRef) const {
對此:
__host__ __device__
double operator()(thrust::device_ptr<double> xDpRef) const {
它可以為我編譯並正確運行(在Linux上):
$ cat t351.cu
#include <iostream>
#include <thrust/device_vector.h>
#include <thrust/host_vector.h>
struct dereference_device_double_functor
{
dereference_device_double_functor() {}
typedef thrust::device_reference<thrust::device_ptr<double>> argument_type;
typedef double result_type;
__host__ __device__
double operator()(thrust::device_ptr<double> xDpRef) const {
thrust::device_ptr<double> xDp = (thrust::device_ptr<double>)xDpRef;
return *xDp;
}
};
struct dereference_host_double_functor
{
dereference_host_double_functor() {}
typedef double* argument_type;
typedef double result_type;
__host__ __device__
double operator()(double* const& xPtr) const {
return *xPtr;
}
};
int main()
{
// Create double
thrust::device_vector<double> dv(1, 5);
thrust::host_vector<double> hv(1, 6);
// Make sure its there
std::cout << dv[0] << std::endl;
std::cout << hv[0] << std::endl;
// Create pointers to doubles
thrust::device_vector<thrust::device_ptr<double>> dvPtr(1);
thrust::device_vector<double*> hvPtr(1);
// Assign pointers to doubles
dvPtr[0] = &(dv[0]);
hvPtr[0] = &(hv[0]);
// Make sure pointers point correctly
std::cout << *((thrust::device_ptr<double>)dvPtr[0]) << std::endl;
std::cout << *(hvPtr[0]) << std::endl;
// Test functor with iterator
auto dvi = dvPtr.begin();
double dvd = dereference_device_double_functor()(*dvi);
auto hvi = hvPtr.begin();
double hvd = dereference_host_double_functor()(*hvi);
// Make sure it worked with iterator
std::cout << dvd << std::endl;
std::cout << hvd << std::endl;
// Make dereferencing transfom iterators
auto tik = thrust::make_transform_iterator(dvPtr.begin(), dereference_device_double_functor());
auto tij = thrust::make_transform_iterator(hvPtr.begin(), dereference_host_double_functor());
// Check that transform iterators work
std::cout << *tik << std::endl; // Will cause compile error: function "dereference_device_double_functor::operator()" cannot be called with the given argument list
std::cout << *tij << std::endl;
return 0;
}
$ nvcc -std=c++11 -o t351 t351.cu
$ cuda-memcheck ./t351
========= CUDA-MEMCHECK
5
6
5
6
5
6
5
6
========= ERROR SUMMARY: 0 errors
$
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