https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103023
--- Comment #2 from bartoldeman at users dot sourceforge.net --- Yes this is about the ICE mainly. It was stripped down from this, which HAS uniform. subroutine func(u,f,ndim) !$OMP DECLARE SIMD(func) uniform(ndim) linear(ref(f,u):1) integer, intent(in) :: ndim double precision, intent(in) :: u(ndim) double precision, intent(out) :: f(ndim) f(1) = u(1) + u(2) f(2) = u(1) - u(2) end subroutine func subroutine main(u,f) double precision, intent(in) :: u(8) double precision, intent(out) :: f(8) !$OMP SIMD do i=1,8,2 call func(u(i),f(i),2) enddo end subroutine main If I leave out ndim and hardcode "2" in func (:: u(2) and :: f(2)), or let the auto-vectorizer and inliner do its work this produces good code (though it would be better with u and f transposed, as basically the code transposes it to two ymm registers in the asm output. With general "ndim" that could still work, e.g. with ndim=3 and 3 equations for u(1:3) -> f(1:3), you'd work with 3 vector registers. Now you may wonder why "ndim" here, since we know it's "2": this comes from feeding a user-defined function into a larger program (that processes e.g. maps) where that same user needs to specify ndim as a parameter. Intel (ifort) doesn't like this at all from what I can see: openfun.f90(1): error #6080: Only scalar variables may be referenced in a LINEAR or MONOTONIC clause. [U] subroutine func(u,f) ----------------^ openfun.f90(1): error #6080: Only scalar variables may be referenced in a LINEAR or MONOTONIC clause. [F] subroutine func(u,f) ------------------^ compilation aborted for openfun.f90 (code 1)