Intel® Fortran Compiler 17.0 Developer Guide and Reference
To parallelize the loop at line %d, annotate the routine %s with %s.
If the loop contains a call to a function, the compiler cannot parallelize the loop without more information about the function being called.
However, if the function being called in the loop is an elemental function or a function specified with ATTRIBUTES CONCURRENCY_SAFE, then the call does not inhibit parallelization of the loop.
Consider the following:
subroutine foo ()
integer, parameter :: N2 = 10000
real (8) :: A(N2), B(N2)
interface
function bar (k)
integer :: bar, k
end function bar
end interface
integer :: i
do i =1, N2
A(i) = B(i) * bar(N2)
end do
end subroutine fooIf you determine it is safe to do so, an alternative way you can modify the program code is as follows:
subroutine foo ()
integer, parameter :: N2 = 10000
real (8) :: A(N2), B(N2)
interface
function bar (k)
!dir$ attributes concurrency_safe : profitable :: bar
integer :: bar, k
end function bar
end interface
integer :: i
do i =1, N2
A(i) = B(i) * bar(N2)
end do
end subroutine fooConfirm the routine satisfies the semantics of this annotation. A weaker annotation able to achieve a similar effect is ATTRIBUTES CONCURRENCY_SAFE(PROFITABLE).