[Bug fortran/30285] gfortran excessive memory usage with large modules

["anlauf at gmx dot de" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #5 from anlauf at gmx dot de  2007-02-02 11:09 -------
> from what i see so far, the problem is in the .mod files, not in the reading of
> them.  there are hundreds of thousands of 'commons' defined, which is silly. 

This gave me the idea to the code below.  Try compiling:


module mod0
  implicit none
  INCLUDE 'mpif.h'
  private
  public :: sub0
contains
  subroutine sub0 ()
  end subroutine sub0
end module mod0

module mod1
  use mod0, only : sub0
  implicit none
  private
  public :: sub1
contains
  subroutine sub1 ()
  end subroutine sub1
end module mod1

module mod2
  use mod0, only : sub0
  use mod1, only : sub1
  implicit none
  private
  public :: sub2
contains
  subroutine sub2 ()
  end subroutine sub2
end module mod2


with mpif.h cut down to:

      INTEGER MPI_BOTTOM
      COMMON /MPIPRIV/ MPI_BOTTOM

and look at the module files.  If you repeat the above,
the module files will explode.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30285