A.23 Examples of the ordered Directive

 

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It is possible to have multiple ordered sections with a for specified with the ordered clause. The first example is noncompliant because the API specifies the following:

"An iteration of a loop with a for construct must not execute the same ordered directive more than once, and it must not execute more than one ordered directive." (See Section 2.6.6 on page 22)

In this noncompliant example, all iterations execute 2 ordered sections:

#pragma omp for ordered  
for (i=0; i<n; i++)   
{  
    ...  
    #pragma omp ordered  
    { ... }  
    ...  
    #pragma omp ordered  
    { ... }  
    ...  
}  

The following compliant example shows a for with more than one ordered section:

#pragma omp for ordered  
for (i=0; i<n; i++)   
{  
    ...  
    if (i <= 10)   
    {  
        ...  
        #pragma omp ordered  
        { ... }  
    }  
    ...  
    (i > 10)   
    {  
        ...  
        #pragma omp ordered  
        { ... }  
    }  
    ...  
}