A.18 Nested for Directives

 

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The following example of for directive nesting (Section 2.9 on page 33) is compliant because the inner and outer for directives bind to different parallel regions:

#pragma omp parallel default(shared)  
{  
    #pragma omp for  
        for (i=0; i<n; i++)   
        {  
            #pragma omp parallel shared(i, n)  
            {  
                #pragma omp for  
                    for (j=0; j<n; j++)  
                        work(i, j);  
            }  
        }  
}  

A following variation of the preceding example is also compliant:

#pragma omp parallel default(shared)  
{  
    #pragma omp for  
        for (i=0; i<n; i++)  
            work1(i, n);  
}  
  
void work1(int i, int n)  
{  
    int j;  
    #pragma omp parallel default(shared)  
    {  
        #pragma omp for  
            for (j=0; j<n; j++)  
                work2(i, j);  
    }  
    return;  
}