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60 lines
1.7 KiB
Fortran
60 lines
1.7 KiB
Fortran
! { dg-do run }
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! { dg-options "-ffixed-form" }
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REAL FUNCTION FN1(I)
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INTEGER I
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FN1 = I * 2.0
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RETURN
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END FUNCTION FN1
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REAL FUNCTION FN2(A, B)
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REAL A, B
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FN2 = A + B
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RETURN
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END FUNCTION FN2
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PROGRAM A18
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INCLUDE "omp_lib.h" ! or USE OMP_LIB
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INTEGER ISYNC(256)
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REAL WORK(256)
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REAL RESULT(256)
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INTEGER IAM, NEIGHBOR
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!$OMP PARALLEL PRIVATE(IAM, NEIGHBOR) SHARED(WORK, ISYNC) NUM_THREADS(4)
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IAM = OMP_GET_THREAD_NUM() + 1
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ISYNC(IAM) = 0
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!$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.
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! The first flush ensures that my work is made visible before
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! synch. The second flush ensures that synch is made visible.
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!$OMP FLUSH(WORK,ISYNC)
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ISYNC(IAM) = 1
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!$OMP FLUSH(ISYNC)
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! Wait until neighbor is done. The first flush ensures that
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! synch is read from memory, rather than from the temporary
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! view of memory. The second flush ensures that work is read
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! from memory, and is done so after the while loop exits.
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IF (IAM .EQ. 1) THEN
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NEIGHBOR = OMP_GET_NUM_THREADS()
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ELSE
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NEIGHBOR = IAM - 1
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ENDIF
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DO WHILE (ISYNC(NEIGHBOR) .EQ. 0)
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!$OMP FLUSH(ISYNC)
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END DO
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!$OMP FLUSH(WORK, ISYNC)
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RESULT(IAM) = FN2(WORK(NEIGHBOR), WORK(IAM))
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!$OMP END PARALLEL
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DO I=1,4
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IF (I .EQ. 1) THEN
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NEIGHBOR = 4
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ELSE
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NEIGHBOR = I - 1
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ENDIF
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IF (RESULT(I) .NE. I * 2 + NEIGHBOR * 2) THEN
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CALL ABORT
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ENDIF
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ENDDO
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END PROGRAM A18
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