RVC by default?

[Aleksey Shipilev]

Hi,

I was looking at some generated code on RISC-V, and realized while we have RVC support, we don't 
enable it by default. On HiFive Unleashed:

$ test-jdk/bin/java -XX:+UnlockExperimentalVMOptions -XX:+PrintFlagsFinal 2>&1 | grep RVC
      bool UseRVC                                   = false                           {ARCH 
experimental} {default}


Is there a reason not to do RVC by default? Can we reliably poll the RVC capabilities in current 
hardware?

-- 
Thanks,
-Aleksey