In the current implementation, scalar
constants are actually inlinable subroutines. As
of version 5.004 of Perl, the appropriate scalar
con- stant is inserted directly in place of some
subroutine calls, thereby saving the overhead of a
subroutine call. See "Constant Functions" in
perlsub for details about how and when this
happens.

##</code><code>##

 
If the result after optimization and constant
folding is either a constant or a lexically-scoped
scalar which has no other references, then it will
be used in place of function calls