int index = readUnsignedShort();
  public final VM_Field getFieldReference() {    if (VM.VerifyAssertions)      VM.assert(opcode == JBC_getstatic || opcode == JBC_putstatic ||                opcode == JBC_getfield || opcode == JBC_putfield);    int index = readUnsignedShort();    return declaringClass.getFieldRef(index);  }