When I run the tests under qemu they pass or fail non-deterministically. Note the difference in "destroy a barrier that has waiting threads" section.

Run 1:

root@qemux86-64:/usr/lib/valgrind/ptest# valgrind --tool=drd --fair-sched=yes ./helgrind/tests/bar_bad
==31394== drd, a thread error detector
==31394== Copyright (C) 2006-2017, and GNU GPL'd, by Bart Van Assche.
==31394== Using Valgrind-3.16.1 and LibVEX; rerun with -h for copyright info
==31394== Command: ./helgrind/tests/bar_bad
==31394== 

initialise a barrier with zero count
==31394== pthread_barrier_init: 'count' argument is zero: barrier 0x4852030
==31394==    at 0x48262D2: pthread_barrier_init_intercept (drd_pthread_intercepts.c:1302)
==31394==    by 0x48262D2: pthread_barrier_init (drd_pthread_intercepts.c:1310)
==31394==    by 0x401273: main (bar_bad.c:43)
==31394== 

initialise a barrier twice
==31394== Barrier reinitialization: barrier 0x4852070
==31394==    at 0x48262D2: pthread_barrier_init_intercept (drd_pthread_intercepts.c:1302)
==31394==    by 0x48262D2: pthread_barrier_init (drd_pthread_intercepts.c:1310)
==31394==    by 0x4012CB: main (bar_bad.c:49)
==31394== barrier 0x4852070 was first observed at:
==31394==    at 0x48262D2: pthread_barrier_init_intercept (drd_pthread_intercepts.c:1302)
==31394==    by 0x48262D2: pthread_barrier_init (drd_pthread_intercepts.c:1310)
==31394==    by 0x4012B5: main (bar_bad.c:48)
==31394== 

initialise a barrier which has threads waiting on it
==31394== Barrier reinitialization: barrier 0x48520b0
==31394==    at 0x48262D2: pthread_barrier_init_intercept (drd_pthread_intercepts.c:1302)
==31394==    by 0x48262D2: pthread_barrier_init (drd_pthread_intercepts.c:1310)
==31394==    by 0x401367: main (bar_bad.c:64)
==31394== barrier 0x48520b0 was first observed at:
==31394==    at 0x48262D2: pthread_barrier_init_intercept (drd_pthread_intercepts.c:1302)
==31394==    by 0x48262D2: pthread_barrier_init (drd_pthread_intercepts.c:1310)
==31394==    by 0x40130D: main (bar_bad.c:55)
==31394== 

destroy a barrier that has waiting threads
==31394== Destruction of a barrier with active waiters: barrier 0x4852350
==31394==    at 0x4826C71: pthread_barrier_destroy_intercept (drd_pthread_intercepts.c:1323)
==31394==    by 0x4826C71: pthread_barrier_destroy (drd_pthread_intercepts.c:1328)
==31394==    by 0x4013F9: main (bar_bad.c:82)
==31394== barrier 0x4852350 was first observed at:
==31394==    at 0x48262D2: pthread_barrier_init_intercept (drd_pthread_intercepts.c:1302)
==31394==    by 0x48262D2: pthread_barrier_init (drd_pthread_intercepts.c:1310)
==31394==    by 0x4013A9: main (bar_bad.c:70)
==31394== 

destroy a barrier that was never initialised
==31394== Not a barrier
==31394==    at 0x4826C71: pthread_barrier_destroy_intercept (drd_pthread_intercepts.c:1323)
==31394==    by 0x4826C71: pthread_barrier_destroy (drd_pthread_intercepts.c:1328)
==31394==    by 0x40148E: main (bar_bad.c:98)
==31394== 
==31394== 
==31394== For lists of detected and suppressed errors, rerun with: -s
==31394== ERROR SUMMARY: 6 errors from 5 contexts (suppressed: 138 from 15)


Run 2:

root@qemux86-64:/usr/lib/valgrind/ptest# valgrind --tool=drd --fair-sched=yes ./helgrind/tests/bar_bad
==31400== drd, a thread error detector
==31400== Copyright (C) 2006-2017, and GNU GPL'd, by Bart Van Assche.
==31400== Using Valgrind-3.16.1 and LibVEX; rerun with -h for copyright info
==31400== Command: ./helgrind/tests/bar_bad
==31400== 

initialise a barrier with zero count
==31400== pthread_barrier_init: 'count' argument is zero: barrier 0x4852030
==31400==    at 0x48262D2: pthread_barrier_init_intercept (drd_pthread_intercepts.c:1302)
==31400==    by 0x48262D2: pthread_barrier_init (drd_pthread_intercepts.c:1310)
==31400==    by 0x401273: main (bar_bad.c:43)
==31400== 

initialise a barrier twice
==31400== Barrier reinitialization: barrier 0x4852070
==31400==    at 0x48262D2: pthread_barrier_init_intercept (drd_pthread_intercepts.c:1302)
==31400==    by 0x48262D2: pthread_barrier_init (drd_pthread_intercepts.c:1310)
==31400==    by 0x4012CB: main (bar_bad.c:49)
==31400== barrier 0x4852070 was first observed at:
==31400==    at 0x48262D2: pthread_barrier_init_intercept (drd_pthread_intercepts.c:1302)
==31400==    by 0x48262D2: pthread_barrier_init (drd_pthread_intercepts.c:1310)
==31400==    by 0x4012B5: main (bar_bad.c:48)
==31400== 

initialise a barrier which has threads waiting on it
==31400== Barrier reinitialization: barrier 0x48520b0
==31400==    at 0x48262D2: pthread_barrier_init_intercept (drd_pthread_intercepts.c:1302)
==31400==    by 0x48262D2: pthread_barrier_init (drd_pthread_intercepts.c:1310)
==31400==    by 0x401367: main (bar_bad.c:64)
==31400== barrier 0x48520b0 was first observed at:
==31400==    at 0x48262D2: pthread_barrier_init_intercept (drd_pthread_intercepts.c:1302)
==31400==    by 0x48262D2: pthread_barrier_init (drd_pthread_intercepts.c:1310)
==31400==    by 0x40130D: main (bar_bad.c:55)
==31400== 

destroy a barrier that has waiting threads

destroy a barrier that was never initialised
==31400== Not a barrier
==31400==    at 0x4826C71: pthread_barrier_destroy_intercept (drd_pthread_intercepts.c:1323)
==31400==    by 0x4826C71: pthread_barrier_destroy (drd_pthread_intercepts.c:1328)
==31400==    by 0x40148E: main (bar_bad.c:98)
==31400== 
==31400== 
==31400== For lists of detected and suppressed errors, rerun with: -s
==31400== ERROR SUMMARY: 4 errors from 4 contexts (suppressed: 138 from 15)


This is observed with valgrind 3.16.1 under qemu x86_64.
I believe this has been also previously reported in https://bugs.kde.org/show_bug.cgi?id=358213 but seemingly never fixed properly.