Shared library undefined reference for CUDA Kernel wrapper - go

Question

So I am attempting to use the CUDA Runtime API with Go's cgo on Windows. I've been at this for a few days now and am stuck: I am getting an undefined reference to my kernel wrapper.
I have separated out my kernel and it's wrapper into the following
FILE: cGo.cuh
typedef unsigned long int ktype;
typedef unsigned char glob;
/*
function Prototypes
*/
extern "C" void kernel_kValid(int, int, ktype *, glob *);
__global__ void kValid(ktype *, glob *);
FILE: cGo.cu
#include "cGo.cuh"
#include "device_launch_parameters.h"
#include "cuda.h"
#include "cuda_runtime.h"
//function Definitions
/*
kernel_kValid is a wrapper function for the CUDA Kernel to be called from Go
*/
extern "C" void kernel_kValid(int blocks, int threads, ktype *kInfo, glob *values) {
kValid<<<blocks, threads>>>(kInfo, values);//execute the kernel
}
/*
kValid is the CUDA Kernel which is to be executed
*/
__global__ void kValid(ktype *kInfo, glob *values) {
//lots of code
}
I compile my CUDA source code into a shared library as such:
nvcc -shared -o myLib.so cGo.cu
then I have created a header file to include in my cgo
FILE: cGo.h
typedef unsigned long int ktype;
typedef unsigned char glob;
/*
function Declarations
*/
void kernel_kValid(int , int , ktype *, glob *);
Then from the go package I utilize cgo to call my kernel wrapper I have
package cuda
/*
#cgo LDFLAGS: -LC:/Storage/Cuda/lib/x64 -lcudart //this is the Cuda library
#cgo LDFLAGS: -L${SRCDIR}/lib -lmyLib //this is my shared library
#cgo CPPFLAGS: -IC:/Storage/Cuda/include //this contains cuda headers
#cgo CPPFLAGS: -I${SRCDIR}/include //this contains cGo.h
#include <cuda_runtime.h>
#include <stdlib.h>
#include "cGo.h"
*/
import "C"
func useKernel(){
//other code
C.kernel_kValid(C.int(B), C.int(T), unsafe.Pointer(storageDevice), unsafe.Pointer(globDevice))
cudaErr, err = C.cudaDeviceSynchronize()
//rest of the code
}
So all of the calls to the CUDA runtime API don't throw errors, it's only my kernel wrapper. This is the output when I build the cuda package with go.
C:\Users\user\Documents\Repos\go\cuda_wrapper>go build cuda_wrapper\cuda
# cuda_wrapper/cuda
In file included from C:/Storage/Cuda/include/host_defines.h:50:0,
from C:/Storage/Cuda/include/device_types.h:53,
from C:/Storage/Cuda/include/builtin_types.h:56,
from C:/Storage/Cuda/include/cuda_runtime.h:86,
from C:\Go\workspace\src\cuda_wrapper\cuda\cuda.go:12:
C:/Storage/Cuda/include/crt/host_defines.h:84:0: warning: "__cdecl" redefined
#define __cdecl
<built-in>: note: this is the location of the previous definition
# cuda_wrapper/cuda
C:\Users\user\AppData\Local\Temp\go-build038297194\cuda_wrapper\cuda\_obj\cuda.cgo2.o: In function `_cgo_440ebb0a3e25_Cfunc_kernel_kValid':
/tmp/go-build\cuda_wrapper\cuda\_obj/cgo-gcc-prolog:306: undefined reference to `kernel_kValid'
collect2.exe: error: ld returned 1 exit status
It's here I'm not really sure what's wrong. I have been looking at questions asked about undefined references with cgo but nothing I have found has solved my issue. I have also been looking at the fact that the CUDA runtime API is written in C++ and if that would affect how cgo will compile this but again I haven't found anything conclusive. At this point I think I have confused myself more than anything else so I'm hoping someone more knowledgeable can point me in the right direction.

Answer 1

Good catch on the name manlging.
Here's a solution we used for gorgonia:
#include <math.h>
#ifdef __cplusplus
extern "C" {
#endif
__global__ void sigmoid32(float* A, int size)
{
int blockId = blockIdx.x + blockIdx.y * gridDim.x + gridDim.x * gridDim.y * blockIdx.z;
int idx = blockId * (blockDim.x * blockDim.y * blockDim.z) + (threadIdx.z * (blockDim.x * blockDim.y)) + (threadIdx.y * blockDim.x) + threadIdx.x;
if (idx >= size) {
return;
}
A[idx] = 1 / (1 + powf((float)(M_E), (-1 * A[idx])));
}
#ifdef __cplusplus
}
#endif
So... just wrap your kernel wrapper function in extern "C"