[Users] CCTK_LOOP3_INT macro with Fortran and OpenMP

[Roland Haas]

Hello Miguel,



> this seems to work fine. however, if i add the OpenMP statements to
> the loop in the "usual" way:
You should leave out the "DO COLLAPSE(3)" and just use "!$OMP PARALLEL
PRIVATE (...)". This will declare a parallel region but no looping
construct (which loopcontrol will do internally).

>    !$OMP PARALLEL DO COLLAPSE(3) &
>    !$OMP PRIVATE(i,j,k, (...))
>    CCTK_LOOP3_INT(int3, i, j, k)
> 
>     (...)
> 
>    CCTK_ENDLOOP3_INT(int3)
>    !$OMP END PARALLEL DO
> 
> the code fails to compile with a bunch of errors:
> 
> Error: Unexpected !$OMP SINGLE statement at (1)
> 
> Error: Unexpected assignment statement at (1)
> 
> Error: Unexpected !$OMP END SINGLE statement at (1)
> 
> (...)
> 
> i've searched around but could not find such an example in the ET
> thorns. is this possible to do? can someone point me in the right
> direction?
Examples on how to use LoopControl are sparse and indeed none for
Fortan may exist.

Note that also in C the proper use is:

--8<--
#pragma omp parallel
CCTK_LOOP3_INT(int3, i, j, k) {
} CCTK_ENDLOOP3_INT(int3);
--8<--

ie only an "omp parallel" and no "parallel for".

Yours,
Roland

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