if (verboseJNI) VM.sysWrite("JNI called: IsAssignableFrom  \n");
if (traceJNI) VM.sysWrite("JNI called: IsAssignableFrom  \n");
  private static boolean IsAssignableFrom(int envJREF, int firstClassJREF,                                           int secondClassJREF) {    if (verboseJNI) VM.sysWrite("JNI called: IsAssignableFrom  \n");    VM_JNIEnvironment env;    try {      env = VM_Thread.getCurrentThread().getJNIEnv();      Class cls1 = (Class) env.getJNIRef(firstClassJREF);      Class cls2 = (Class) env.getJNIRef(secondClassJREF);      if (cls1==null || cls2==null)        return false;      return cls2.isAssignableFrom(cls1);    } catch (Throwable unexpected) {      env = VM_Thread.getCurrentThread().getJNIEnv();      env.recordException(unexpected);      return false;    }  }