Shenandoah C2 barrier verification is disabled when unusual barrier configuration is requested. However, that only takes care of options provided from the command line (as our tests assert). For the configuration that disables barriers implicitly, e.g. x86_32, this is not enough, and tests fail with false negatives. We need to disable C2 barriers verification explicitly there.

diff -r 5e7316970e87 src/hotspot/share/gc/shenandoah/shenandoahArguments.cpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahArguments.cpp Mon May 06 19:27:40 2019 +0200
+++ b/src/hotspot/share/gc/shenandoah/shenandoahArguments.cpp Mon May 06 19:43:46 2019 +0200
@@ -50,6 +50,8 @@
   FLAG_SET_DEFAULT(ShenandoahStoreValEnqueueBarrier, false);
   FLAG_SET_DEFAULT(ShenandoahCASBarrier, false);
   FLAG_SET_DEFAULT(ShenandoahCloneBarrier, false);
+
+ FLAG_SET_DEFAULT(ShenandoahVerifyOptoBarriers, false);
 #endif
 
 #ifdef _LP64