Recursive function and pass by VALUE optimizations

Hi all,

I have some questions about the recursive functions performance in the compiler.

The code is below, the performance table obtains with the compiler 14.  First column is normal, second column is pass by value.

Ifort is slower than gfortran(4.8.2), and is passing by reference creating more copies in the recursive case ?

I don't know if performance is better with old compiler version.

Thanks.

ifort         3.51  1.151

gfortran  2.027  0.452

program ackermann
         implicit none
   write(*,*) ack(3, 12)
   contains
 recursive function ack(m, n) result(a)
   integer, intent(in) :: m,n
   integer :: a

   if (m == 0) then
     a=n+1
   else if (n == 0) then
     a=ack(m-1,1)
   else
     a=ack(m-1, ack(m, n-1))
   end if
 end function ack
 end program ackermann