[Bug fortran/56907] New: C_LOC shall not call internal-PACK when an array argument is used

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56907



             Bug #: 56907

           Summary: C_LOC shall not call internal-PACK when an array

                    argument is used

    Classification: Unclassified

           Product: gcc

           Version: 4.9.0

            Status: UNCONFIRMED

          Keywords: missed-optimization

          Severity: normal

          Priority: P3

         Component: fortran

        AssignedTo: unassig...@gcc.gnu.org

        ReportedBy: bur...@gcc.gnu.org





Found when looking at gfortran.dg/assumed_type_2.f90.



For an array argument, C_LOC should simply take the first element of the array

(section). Currently, it invokes internal packing.



As Fortran 2008 demands that the argument is contiguous, internal_packing

should simply return the original array (section) - hence, there is no

wrong-code issue - just a missed optimization.



>From the dump:

    D.1901 = _gfortran_internal_pack (&parm.4);

    D.1903 = D.1901;



Test case:



! { dg-do compile }

! { dg-options "-fdump-tree-original" }

!

! PR fortran/ <<<<<<<<<<<

!



subroutine sub(xxx)

  use iso_c_binding

  implicit none

  integer, target :: xxx(:)

  type(c_ptr) :: ptr

  ptr = c_loc (xxx)

end

! { dg-final { scan-tree-dump-not " _gfortran_internal_pack" "original" } }

! { dg-final { cleanup-tree-dump "optimized" } }