I updated Android Studio to 2.0 Preview 2, then I got an error Renderscript support mode is not currently supported with renderscript target 21+
I'm using renderscriptTargetApi 23
Renderscript isn't currently supported with Target 21+ so simply change the target to API 20 and that should solve the error. So the renderscript related options in your default config section of your gradle file should like :
renderscriptTargetApi 20
renderscriptSupportModeEnabled true