Product Version: Intel(R) Visual Fortran Compiler XE 15.0.0.070
Cause:
The vectorization report generated when using Visual Fortran Compiler's optimization options (-O2 -Qopt-report:2) states that loop was not vectorized since loop body became empty after optimizations.
Example:
An example below will generate the following remark in optimization report:
integer function foo(a, b, n)
implicit none
integer, intent(in) :: n
real, intent(inout) :: a
real, intent (in) :: b
integer :: i
do i=1,n
a = b + 1
end do
foo = a
end function Report from: Vector optimizations [vec]
LOOP BEGIN at f15414.f90(8,5)
remark #15414: loop was not vectorized: nothing to vectorize since loop body became empty after optimizations
LOOP END
Resolution:
In the example above, there is only one expression inside the loop. When moved outside the loop as a result of the compiler's optimization process there is nothing else left inside the loop to vectorize.
See also:
Requirements for Vectorizable Loops
Vectorization and Optimization Reports