[llvm-bugs] [Bug 49613] New: Segmentation fault: OpenMP critical hint(omp_sync_hint_uncontended):

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=49613

            Bug ID: 49613
           Summary: Segmentation fault: OpenMP critical
                    hint(omp_sync_hint_uncontended):
           Product: OpenMP
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Runtime Library
          Assignee: unassignedbugs at nondot.org
          Reporter: kim.walisch at gmail.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 24654
  --> https://bugs.llvm.org/attachment.cgi?id=24654&action=edit
Bash script that reproduces the segmentation fault

Hi,

While trying out the omp_sync_hint_uncontended synchronization hint with a
critical section I have hit a segmentation fault (Clang 11, Ubuntu 20.04 x64,
Intel i7-6700 CPU). With another synchronization hint such as
omp_sync_hint_contended or without any synchronization hint there is no
segmentation fault.

The attached crash-omp_sync_hint_uncontended.sh bash script clones my
primecount OpenMP project, changes the critical sections in the file
src/gourdon/AC.cpp to use the omp_sync_hint_uncontended synchronization hint,
builds the primecount program using clang++-11 (hardcoded in the bash script)
and then runs the program which immediately causes the segmentation fault:

$ ./crash-omp_sync_hint_uncontended.sh
./crash-omp_sync_hint_uncontended.sh: line 13: 71249 Segmentation fault     
(core dumped) ./primecount 1e15 --AC

I have also run the primecount binary using valgrind which gives a stack trace
of where the segmentation fault happened. I have attached the valgrind output
(Segmentation-fault.txt) to this bug report.

Regards,
Kim Walisch

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