https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115802
--- Comment #9 from Ivan Bodrov <securesneakers at gmail dot com> --- Created attachment 58598 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58598&action=edit Minimal program to reproduce the issue (no condvar) To further simplify the original code, the condition variable can be excluded and the waiter code can be replaced with unlock-then-lock: mutex_lock(&mtx); while (!val) { mutex_unlock(&mtx); mutex_lock(&mtx); } mutex_unlock(&mtx); This might be a better demonstration. Will hang the same way for the same reason: $ gcc -O2 minimal-executable-no-cond.c $ ./a.out
