[Bug fortran/40973] New: Mark PRIVATE module functions as STATIC to faciliate optimization

["burnus at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

We should consider marking module procedures with PRIVATE attribute as STATIC
(in the C sense) such that they can be eliminated. In the following program,
"two" could be optimized away as it cannot be called from outside the module.
However, this does not happen with

  gfortran -O3 -c test.f90    (nor with ifort -O3 -c test, nor for NAG f95,
openf95)

as "nm test.o" shows. I think STATIC does the right thing also if it is used as
in the following example:

  procedure(), pointer :: ptr  ! e.g. dummy argument, module variable, local
variable ...
  ptr => two

I think one cannot mark it as STATIC if it has a C binding name, i.e. PRIVATE
but bind(C). It can be marked as STATIC, however, if it has no binding name: 
bind(C,name="").

(Maybe I miss something as this optimization does not happen for so many
compilers, but I fail to see the flaw.)


MODULE M
  PRIVATE :: two
CONTAINS
  SUBROUTINE one(a)
    integer :: a
    a = two()
  END SUBROUTINE one
  integer FUNCTION two()
     two = 42
  END FUNCTION two
END MODULE


-- 
           Summary: Mark PRIVATE module functions as STATIC to faciliate
                    optimization
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: burnus at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40973