http://cr.openjdk.java.net/~vlivanov/8234401/webrev.00/ https://bugs.openjdk.java.net/browse/JDK-8234401
ConstantCallSite has a ctor which deliberately leaks partially initialized instance into user code. isFrozen is declared final and if user code is obstinate enough, it can end up with non-frozen state embedded into the generated code. It manifests as a ConstantCallSite instance which is stuck in non-frozen state.
I switched isFrozen from final to @Stable, so non-frozen state is never constant folded. Put some store-store barriers along the way to restore final field handling.
I deliberately stopped there (just restoring isFrozen final field behavior). Without proper synchronization, there's still a theoretical possibility of transiently observing a call site in non-frozen state right after ctor is over. But at least there's no way anymore to accidentally break an instance in such a way it becomes permanently unusable.
PS: converted CallSite.target to final along the way and made some other minor refactorings.
Testing: regression test, tier1-2 Best regards, Vladimir Ivanov
