[Bug fortran/83017] DO CONCURRENT not parallelizing

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83017

--- Comment #6 from rguenther at suse dot de <rguenther at suse dot de> ---
On November 16, 2017 2:22:50 PM GMT+01:00, cfztol at hotmail dot com
<gcc-bugzilla@gcc.gnu.org> wrote:
>https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83017
>
>--- Comment #5 from Christian Felter <cfztol at hotmail dot com> ---
>Okay, sounds like there is hope. By the way, the problem also exists
>without a
>function call. Declaring
>
>     real, dimension(nsplit) :: tmp
>
>and replacing the loop with
>
>     do concurrent (i = 1:nsplit)
>
>         tmp = 0
>         do j = low(i), high(i)    
>             k = mod( j, nsplit ) + 1
>             tmp(k) = tmp(k) + (-1)**(j+1) / real( 2*j-1 )
>         end do
>         pi(i) = sum(tmp)    
>
>     end do
>
>also inhibits parallelization.

What does do concurrent guarantee?