68 lines
1.5 KiB
C
68 lines
1.5 KiB
C
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/* { dg-do run } */
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#include <omp.h>
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#include <stdio.h>
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extern void abort (void);
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#define NUMBER_OF_THREADS 4
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int synch[NUMBER_OF_THREADS];
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int work[NUMBER_OF_THREADS];
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int result[NUMBER_OF_THREADS];
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int
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fn1 (int i)
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{
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return i * 2;
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}
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int
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fn2 (int a, int b)
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{
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return a + b;
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}
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int
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main ()
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{
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int i, iam, neighbor;
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omp_set_num_threads (NUMBER_OF_THREADS);
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#pragma omp parallel private(iam,neighbor) shared(work,synch)
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{
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iam = omp_get_thread_num ();
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synch[iam] = 0;
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#pragma omp barrier
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/*Do computation into my portion of work array */
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work[iam] = fn1 (iam);
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/* Announce that I am done with my work. The first flush
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* ensures that my work is made visible before synch.
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* The second flush ensures that synch is made visible.
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*/
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#pragma omp flush(work,synch)
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synch[iam] = 1;
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#pragma omp flush(synch)
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/* Wait for neighbor. The first flush ensures that synch is read
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* from memory, rather than from the temporary view of memory.
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* The second flush ensures that work is read from memory, and
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* is done so after the while loop exits.
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*/
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neighbor = (iam > 0 ? iam : omp_get_num_threads ()) - 1;
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while (synch[neighbor] == 0)
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{
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#pragma omp flush(synch)
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}
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#pragma omp flush(work,synch)
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/* Read neighbor's values of work array */
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result[iam] = fn2 (work[neighbor], work[iam]);
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}
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/* output result here */
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for (i = 0; i < NUMBER_OF_THREADS; i++)
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{
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neighbor = (i > 0 ? i : NUMBER_OF_THREADS) - 1;
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if (result[i] != i * 2 + neighbor * 2)
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abort ();
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}
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return 0;
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}
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