[Bug fortran/112338] New: ieee_set_halting_mode only affects the master thread outside of an OpenMP parallel region

[Bug fortran/112338] New: ieee_set_halting_mode only affects the master thread outside of an OpenMP parallel region

[vladimir.fuka at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112338

            Bug ID: 112338
           Summary: ieee_set_halting_mode only  affects the master thread
                    outside of an OpenMP parallel region
           Product: gcc
           Version: 13.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vladimir.fuka at gmail dot com
  Target Milestone: ---

Calling ieee_set_halting_mode only affects the master thread if other threads
already exist and the call is done outside of a parallel region. I am not sure
what the Fortran standard and the OpenMP specifications prescribe, but the
following code produces different results with GCC and with Intel.

    use ieee_exceptions 

    implicit none

    integer, parameter :: n = 100
    real :: nom(n)
    integer :: denom(n)

    logical :: saved_fpe_mode(size(ieee_all))
    integer :: i

    nom = 1
    denom = 0

    call ieee_set_halting_mode(ieee_overflow, .true.)
    call ieee_set_halting_mode(ieee_invalid, .true.)
    call ieee_set_halting_mode(ieee_divide_by_zero, .true.)

    !$omp parallel
    print *,"hello from a thread"
    !$omp end parallel

    call ieee_get_halting_mode(ieee_all, saved_fpe_mode)
    call ieee_set_halting_mode(ieee_all, .false.)

    !$omp parallel do
    do i = 1, n
      nom(i) = nom(i) / denom(i)
    end do
    !$omp end parallel do


    nom = min(max(0., nom), 1.)

    !$omp parallel
    call ieee_set_halting_mode(ieee_all, saved_fpe_mode)
    !$omp end parallel

    print *, nom
end




With GCC 

gfortran-13 -fopenmp -g fpe.f90

the code halts on line 28 (nom(i) = nom(i) / denom(i)) with SIGFPE:
Floating-point exception - erroneous arithmetic operation.


With Intel

ifx -qopenmp -g fpe.f90

the code does not halt and prints all 1.000000s.

[Bug fortran/112338] ieee_set_halting_mode only affects the master thread outside of an OpenMP parallel region

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112338

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
My bet it is not described ...