[Bug fortran/52075] New: OpenMP atomic update failing if -fbounds-check specified

["longb at cray dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52075

             Bug #: 52075
           Summary: OpenMP atomic update failing if -fbounds-check
                    specified
    Classification: Unclassified
           Product: gcc
           Version: 4.6.2
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: longb@cray.com


Test code:

!  derived from OpenMP test OMP3f/F03_2_8_5_3.F90
program F03_2_8_5_3
! thread-num n sets bit 2**n in each element of the array (assuming 2**n can
! be represented by the data type). Each element of the array should contain
! 2**num-threads - 1.
   use omp_lib
   implicit none

   integer, parameter :: NT = 4
   integer, parameter :: ARRAY_SIZE = 1024
   integer :: X(ARRAY_SIZE) = 0, v, i

   call omp_set_dynamic(.false.);
   call omp_set_num_threads(NT); 

   !$omp parallel private(v)
   if (omp_get_thread_num() < STORAGE_SIZE(X)) then
      do i = 1, ARRAY_SIZE
         !$omp atomic
         X(i) = IOR(X(i), 2**omp_get_thread_num())
      end do
   end if
   !$omp end parallel

   do i = 1, ARRAY_SIZE
      if (X(i) /= MASKR(MIN(NT, STORAGE_SIZE(X)))) then
         write (*,*) 'FAIL - X(', i, ') == ', X(i), ' (expected ', &
                  MASKR(MIN(NT, STORAGE_SIZE(X))),')'
         stop 1
      end if
   end do

end program F03_2_8_5_3


Works as expected with just -fopenmp:

> ftn -fopenmp  test.f90
> aprun -n1 -d4 ./a.out
Application 6244707 resources: utime ~0s, stime ~0s
>

Failing (wrong answer) if -fbounds-check is also specified:

> ftn -fopenmp -fbounds-check test.f90
> aprun -n1 -d4 ./a.out
 FAIL - X(           1 ) ==            7  (expected           15 )
STOP 1
Application 6244710 exit codes: 1
Application 6244710 resources: utime ~0s, stime ~0s