[Bug libgomp/35881] New: OMP atypical results for omp_get_max_threads

[jv244 at cam dot ac dot uk]

The following test program returns 1 for omp_get_max_threads in a parallel
region. This is different from what I get with three other compilers, and hence
somewhat unexpected. Is this correct, and if so, should it be the default?

> gfortran -v
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: /data03/vondele/gcc_4_3_0_release/gcc-4.3.0/configure
--prefix=/ext/software/64/gfortran-suite/gcc-4.3.0
--enable-languages=c,c++,fortran
Thread model: posix
gcc version 4.3.0 (GCC)

SUBROUTINE TEST()
   IMPLICIT NONE
   INTEGER :: ithread,nthread,mthread
!$ INTEGER :: omp_get_thread_num, omp_get_max_threads, omp_get_num_threads

   ithread=0
   nthread=1
   mthread=1

!$ nthread=omp_get_max_threads()
   write(6,*) ithread,nthread,mthread

!$OMP PARALLEL PRIVATE(ithread,nthread,mthread)
!$ nthread=omp_get_max_threads()
!$ mthread=omp_get_num_threads()
!$ ithread=omp_get_thread_num()
!$OMP CRITICAL
   write(6,*) ithread,nthread,mthread
!$OMP END CRITICAL
!$OMP END PARALLEL

END SUBROUTINE TEST

CALL TEST()

END


IBM:
vondele@blanc161:~> xlf90_r -qsuffix=f=f90 -O3 -qsmp=omp test.f90
** test   === End of Compilation 1 ===
** _main   === End of Compilation 2 ===
1501-510  Compilation successful for file test.f90.
vondele@blanc161:~> ./a.out
 0 4 1
 0 4 4
 1 4 4
 3 4 4
 2 4 4

vondele@pcihopt3:/data03/vondele/openmp> pgf90 -openmp test.f90
vondele@pcihopt3:/data03/vondele/openmp> ./a.out
           0           4           1
           0           4           4
           1           4           4
           2           4           4
           3           4           4

vondele@pcihopt3:/data03/vondele/openmp> ifort -O0 -openmp test.f90
test.f90(13): (col. 7) remark: OpenMP DEFINED REGION WAS PARALLELIZED.
vondele@pcihopt3:/data03/vondele/openmp> ./a.out
           0           4           1
           0           4           4
           1           4           4
           2           4           4
           3           4           4

vondele@pcihopt3:/data03/vondele/openmp> gfortran  -O0 -fopenmp test.f90
vondele@pcihopt3:/data03/vondele/openmp> ./a.out
           0           4           1
           0           1           4
           1           1           4
           2           1           4
           3           1           4


-- 
           Summary: OMP atypical results for omp_get_max_threads
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libgomp
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jv244 at cam dot ac dot uk


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35881