[llvm-bugs] [Bug 30890] New: Reduction across teams hangs at __kmpc_end_reduce()

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=30890

            Bug ID: 30890
           Summary: Reduction across teams hangs at __kmpc_end_reduce()
           Product: OpenMP
           Version: unspecified
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Runtime Library
          Assignee: unassignedbugs at nondot.org
          Reporter: grokos at us.ibm.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Tested on x86_64 and ppc64le, RHEL.

The following code which involves a reduction across teams when target
offloading is disabled never runs to completion.

#include <omp.h>

int main() {
  int nthreads = 0;

  #pragma omp target teams num_teams(4) map(tofrom: nthreads) \
              if(target:0) reduction(+:nthreads)
  {
    nthreads = omp_get_num_threads();
  }

  return 0;
}

Execution freezes while calling __kmpc_end_reduce(). It seems threads are
spinning forever at a hyper-barrier (__kmp_hyper_barrier_gather()).

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20161102/e702fe9b/attachment.html>