[OpenMP RT] issue-94260-2.c tests rarely segfaults

[mikaoP]

Running tests on a shared cluster I noticed issue-94260-2.c failed. I only managed to reproduce de segfault by running it in a:

while /path/to/build/runtimes/runtimes-bins/openmp/runtime/test/tasking/Output/issue-94260-2.c.tmp ; do date; done

EDIT1: I ran in a Debug build
EDIT: I managed to get a coredump :) and it seems that

https://github.com/llvm/llvm-project/blob/main/openmp/runtime/src/kmp_tasking.cpp#L3236
other_pthread is 0xefefefefefefefef

Also I see some threads in the:

__kmp_fork_barrier -> __kmp_hyper_barrier_release

while others are in:

__kmpc_reduce_nowait -> __kmp_barrier -> __kmp_hyper_barrier_gather

[llvmbot]

@llvm/issue-subscribers-openmp

Author: None (mikaoP)

Running tests on a shared cluster I noticed issue-94260-2.c failed. I only managed to reproduce de segfault by running it in a:

while /path/to/build/runtimes/runtimes-bins/openmp/runtime/test/tasking/Output/issue-94260-2.c.tmp ; do date; done

[LewisCrawford]

This seems to be a fairly frequent intermittent failure on the LLVM buildbot too (6 failures out of the latest 200 runs).
Some examples from the past 5 days of runs failing due to this:

• https://lab.llvm.org/buildbot/#/builders/88/builds/16868
• https://lab.llvm.org/buildbot/#/builders/88/builds/16832
• https://lab.llvm.org/buildbot/#/builders/88/builds/16788
• https://lab.llvm.org/buildbot/#/builders/88/builds/16773
• https://lab.llvm.org/buildbot/#/builders/88/builds/16711
• https://lab.llvm.org/buildbot/#/builders/88/builds/16676

It's been happening for at least a few months though. Some examples from back in August:

• https://lab.llvm.org/buildbot/#/builders/88/builds/15015
• https://lab.llvm.org/buildbot/#/builders/88/builds/14946
• https://lab.llvm.org/buildbot/#/builders/88/builds/14920

[LewisCrawford]

CC @jpeyton52 , who added this test in PR #95823 while fixing issue #94260