Some versions of Intel Fortran produce code that yields segmentation fault, while some others don't

Jozsef_K_ · ‎06-05-2015

Dear Community,

I have encountered some weird phenomenon involving Fortran array operations. The following code

PROGRAM test
  IMPLICIT NONE

  INTEGER, PARAMETER :: dp = 8
  INTEGER, PARAMETER :: N = 10
  INTEGER :: i, no_onedir_points, no_quadrature_points
  REAL(dp), DIMENSION(1:N*N) :: w
  REAL(dp), DIMENSION(1:n) :: gw

  no_onedir_points = N
  no_quadrature_points = N*N

  DO i = 1, N
    gw( i ) = REAL( i, dp )
  ENDDO    ! i

  w(  1:no_quadrature_points ) = &
              PACK( ARRAY=SPREAD( SOURCE=gw(1:no_onedir_points), &
                                  DIM=2, &
                                  NCOPIES=no_onedir_points ) * &
                          SPREAD( SOURCE=gw(1:no_onedir_points), &
                                  DIM=1, &
                                  NCOPIES=no_onedir_points ),  &
                    MASK=.TRUE. )

  WRITE(*,*) gw
  WRITE(*,*) w

END PROGRAM test

is a (rather simplified) snippet from a FEM code to generate some tensor products of arrays.

Compiling it by Intel Fortan 2015 Update 3 (ifort version 15.0.3) the resulting code suffers segfault at the call to PACK. Turning to Intel Fortran 2015 (ifort version 15.0.1) yields the same. However, if the code above is compiled with Intel Fortran 2013 SP1 Update 3 (ifort version 14.0.2) then everything works fine and the expected result is produced.

Moreover, if I modify the above code to avoid the "embedded" calls to SPREAD within PACK using a temporary array

PROGRAM test
  IMPLICIT NONE

  INTEGER, PARAMETER :: dp = 8
  INTEGER, PARAMETER :: N = 10
  INTEGER :: i, no_onedir_points, no_quadrature_points
  REAL(dp), DIMENSION(1:N*N) :: w
  REAL(dp), DIMENSION(1:N,1:N) :: data
  REAL(dp), DIMENSION(1:n) :: gw

  no_onedir_points = N
  no_quadrature_points = N*N

  DO i = 1, N
    gw( i ) = REAL( i, dp )
  ENDDO    ! i


  data(1:no_onedir_points,1:no_onedir_points) = &
                          SPREAD( SOURCE=gw(1:no_onedir_points), &
                                  DIM=2, &
                                  NCOPIES=no_onedir_points ) * &
                          SPREAD( SOURCE=gw(1:no_onedir_points), &
                                  DIM=1, &
                                  NCOPIES=no_onedir_points )

  w(  1:no_quadrature_points ) = &
              PACK( ARRAY=data(1:no_onedir_points,1:no_onedir_points),  &
                    MASK=.TRUE. )

  WRITE(*,*) gw
  WRITE(*,*) w

END PROGRAM test

then everything is going fine with ifort version 15.0.3.

Am I doing something wrong, or is this a bug somewhere?

Thank you for your help,

Jozsef

Steven_L_Intel1 · ‎06-05-2015

See https://software.intel.com/en-us/forums/topic/559308