pointer attachment example

ptr-atmt.c

// clang -fopenmp ptr-atmt.c -o ptr-atmt
#include <omp.h>
#include <stdio.h>


#pragma omp declare target
double *ptr;
void work(int i)
{
     // work on ptr[i]
     // ...
     printf("[dev] work(%d): ptr = %p\n", i, ptr);
}
#pragma omp end declare target

// work() is a device kernel, and ptr is also on the device


void foo(double arr[], size_t sz)
{
     ptr = arr;
     #pragma omp target map(ptr[0:sz])
     #pragma omp teams distribute
     for (int i = 0; i < sz; i++) {
           printf("[host] will work(%d): ptr = %p\n", i, ptr);
           work( i );
     }
}

int main(void) {
        double array[] = { 1, 2 };
        foo(array, 2);
}