A.14 使用不带列表的 flush 指令

下面的示例 (对于第 20 页) 的 第2.6.5部分 区分 flush 指令的影响共享对象不会从不受影响的共享对象列表:

示例

代码

// omp_flush_without_list.c
#include <omp.h>

int x, *p = &x;

void f1(int *q)
{
    *q = 1;
    #pragma omp flush
    // x, p, and *q are flushed
    //   because they are shared and accessible
    // q is not flushed because it is not shared.
}

void f2(int *q)
{
    #pragma omp barrier
    *q = 2;

    #pragma omp barrier
    // a barrier implies a flush
    // x, p, and *q are flushed
    //   because they are shared and accessible
    // q is not flushed because it is not shared.
}

int g(int n)
{
    int i = 1, j, sum = 0;
    *p = 1;

    #pragma omp parallel reduction(+: sum) num_threads(10)
    {
        f1(&j);
        // i, n and sum were not flushed
        //   because they were not accessible in f1
        // j was flushed because it was accessible
        sum += j;
        f2(&j);
        // i, n, and sum were not flushed
        //   because they were not accessible in f2
        // j was flushed because it was accessible
        sum += i + j + *p + n;
    }
    return sum;
}

int main()
{
}