concurrency - 为什么 DO CONCURRENT 语句会给出奇怪的结果？

Question

让我们编译以下 Fortran 程序：

program main
    implicit none
    integer::j
    complex::y(2)
    real::x(2)

    x(1)=1.0
    x(2)=2.0

    do j=1,2
        y(j)=FF(x(j))
    enddo

    write(6,*)
    write(6,*) y,"by DO"

    forall (integer::i=1:2)
        y(i)=FF(x(i))
    end forall

    write(6,*)
    write(6,*) y,"by FORALL"

    do concurrent (integer::i=1:2)
        y(i)=FF(x(i))
    enddo

    write(6,*)
    write(6,*) y,"by DO CONCURRENT"
    write(6,*)

    contains
    complex pure function FF(xx)
        real,intent(in)::xx
        FF=cmplx(xx)
    end function
end program

ifort (ver. 19.0.4.243) 没有选项。然后，我们得到结果：

$ ./a.out

 (1.000000,0.0000000E+00) (2.000000,0.0000000E+00) by DO

 (1.000000,0.0000000E+00) (2.000000,0.0000000E+00) by FORALL

 (2.000000,0.0000000E+00) (2.000000,0.0000000E+00) by DO CONCURRENT

第一个和第二个结果符合预期。为什么 DO CONCURRENT 不给出相同的结果？

标签： concurrencyfortranintel-fortranfortran2008