Question

Inside of a kernel, is it OK to pass the address of a struct, which is declared inside the kernel, to a device function? The device function’s argument is a pointer to a struct.

Answer 1

Yes, as the following program demonstrates:

#include <stdio.h>

struct my_struct
{
  int x;
};

// foo receives its argument by pointer
__device__ void foo(my_struct *a)
{
  a->x = 13;
}

__global__ void kernel()
{
  my_struct a;
  a.x = 7;

  // expect 7 in the printed output
  printf("a.x before foo: %d\n", a.x);

  foo(&a);

  // expect 13 in the printed output
  printf("a.x after foo: %d\n", a.x);
}

int main()
{
  kernel<<<1,1>>>();
  cudaThreadSynchronize();
  return 0;
}

The result:

$ nvcc -arch=sm_20 test.cu -run
a.x before foo: 7
a.x after foo: 13