These test cases illustrate that gfortran ignores the COLLAPSE(M) clause on
an !$OMP DO when the value given is not a constant (or declared as a variable
having the parameter attribute. Other compilers supporting OpenMP API 3.0
raise an error when the primary test case is compiled.
The expected output should be an error similar to that raised by either the
Intel or PGI compilers.
> cat ISU3102.f90
! collapse not having a constant value
program test
use omp_lib
implicit none
integer :: j,k
integer :: m = 2
! integer,parameter :: m = 2
!$omp parallel num_threads(2) private(j,k)
!$omp do collapse(m) schedule (static,1)
do k = 1,2
do j = 1,6
print *, k, j, omp_get_thread_num()
enddo
enddo
!$omp end do
!$omp end parallel
end
> diff ISU3102.f90 ISU3102p.f90
6,7c6,7
< integer :: m = 2
< ! integer,parameter :: m = 2
---
> ! integer :: m = 2
> integer,parameter :: m = 2
> diff ISU3102.f90 ISU3102noc.f90
9c9
< !$omp do collapse(m) schedule (static,1)
---
> !$omp do schedule (static,1)
BAD - The collapse clause is ignored rather than having an error detected:
> setenv OMP_NUM_THREADS 2
> gfortran -o x -fopenmp ISU3102.f90
> ./x | sort
1 1 0
1 2 0
1 3 0
1 4 0
1 5 0
1 6 0
2 1 1
2 2 1
2 3 1
2 4 1
2 5 1
2 6 1
Expected output when value m has parameter attribute (constant):
> gfortran -o xp -fopenmp ISU3102p.f90
> ./xp | sort
1 1 0
1 2 1
1 3 0
1 4 1
1 5 0
1 6 1
2 1 0
2 2 1
2 3 0
2 4 1
2 5 0
2 6 1
Output when no collapse clause is present:
> ./xnoc | sort
1 1 0
1 2 0
1 3 0
1 4 0
1 5 0
1 6 0
2 1 1
2 2 1
2 3 1
2 4 1
2 5 1
2 6 1
Ifort (intel) raises an error:
> ifort -openmp -o ix ISU3102.f90 -liomp5
ISU3102.f90(9): error #8167: COLLAPSE operand must be an integer expression
!$omp do collapse(m) schedule (static,1)
---------^
compilation aborted for ISU3102.f90 (code 1)
PGI raises an error:
> pgf90 -mp -o px ISU3102.f90
PGF90-S-0155-The COLLAPSE expression must be a positive integer constant
(ISU3102.f90: 9)
0 inform, 0 warnings, 1 severes, 0 fatal for test
ifort (intel) o.k. with a value that is a parameter:
> ifort -openmp -o ixp ISU3102p.f90 -liomp5
ISU3102p.f90(9): (col. 7) remark: OpenMP DEFINED LOOP WAS PARALLELIZED.
ISU3102p.f90(8): (col. 7) remark: OpenMP DEFINED REGION WAS PARALLELIZED.
PGI o.k. with a value that is a parameter:
> pgf90 -mp -o pxp ISU3102p.f90
--
Summary: !$omp collapse(m) with non-constant m should give error
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: longb at cray dot com
GCC build triplet: x86_64-suse-linux
GCC host triplet: x86_64-suse-linux
GCC target triplet: x86_64-suse-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40878
