我正在尝试添加一个cuda后端到一个20k的loc c++表达式模板库。到目前为止,它工作得很好,但我完全被“警告:从__host__ __device__
函数调用__host__
函数是不允许的”警告淹没了。
大部分代码可以总结如下:
template<class Impl>
struct Wrapper{
Impl impl;
// lots and lots of decorator code
__host__ __device__ void call(){ impl.call();};
};
//Guaranteed to never ever be used on gpu.
struct ImplCPU{
void call();
};
//Guaranteed to never ever be used on cpu.
struct ImplGPU{
__host__ __device__ void call();//Actually only __device__, but needed to shut up the compiler as well
};
Wrapper<ImplCPU> wrapCPU;
Wrapper<ImplGPU> wrapGPU;
在所有情况下,包装器中的call()都是微不足道的,而包装器本身是一个相当复杂的野兽(只有包含元信息的主机函数)。条件编译不是一个选项,两个路径都应该同时使用。
我离“--禁用-警告”还差一步,因为老实说,复制和维护10k个可怕的模板魔法的成本超过了警告的好处。
我非常高兴有一种方法可以根据实现是针对gpu还是针对cpu来有条件地调用device或host (因为Impl知道它的用途)。
只是为了显示它是坏的。一条警告:
/home/user/Remora/include/remora/detail/matrix_expression_classes.hpp(859): warning: calling a __host__ function from a __host__ __device__ function is not allowed
detected during:
instantiation of "remora::matrix_matrix_prod<MatA, MatB>::size_type remora::matrix_matrix_prod<MatA, MatB>::size1() const [with MatA=remora::dense_triangular_proxy<const float, remora::row_major, remora::lower, remora::hip_tag>, MatB=remora::matrix<float, remora::column_major, remora::hip_tag>]"
/home/user/Remora/include/remora/cpu/../assignment.hpp(258): here
instantiation of "MatA &remora::assign(remora::matrix_expression<MatA, Device> &, const remora::matrix_expression<MatB, Device> &) [with MatA=remora::dense_matrix_adaptor<float, remora::row_major, remora::continuous_dense_tag, remora::hip_tag>, MatB=remora::matrix_matrix_prod<remora::dense_triangular_proxy<const float, remora::row_major, remora::lower, remora::hip_tag>, remora::matrix<float, remora::column_major, remora::hip_tag>>, Device=remora::hip_tag]"
/home/user/Remora/include/remora/cpu/../assignment.hpp(646): here
instantiation of "remora::noalias_proxy<C>::closure_type &remora::noalias_proxy<C>::operator=(const E &) [with C=remora::matrix<float, remora::row_major, remora::hip_tag>, E=remora::matrix_matrix_prod<remora::dense_triangular_proxy<const float, remora::row_major, remora::lower, remora::hip_tag>, remora::matrix<float, remora::column_major, remora::hip_tag>>]"
/home/user/Remora/Test/hip_triangular_prod.cpp(325): here
instantiation of "void Remora_hip_triangular_prod::triangular_prod_matrix_matrix_test(Orientation) [with Orientation=remora::row_major]"
/home/user/Remora/Test/hip_triangular_prod.cpp(527): here
https://stackoverflow.com/questions/52152898
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