public int blockIndexToRopLabel(int bi) {
    if (bi < 0) {
      return -1;
    }
    return blocks.get(bi).getRopLabel();
  }
@param bi block index or {@code -1} for none
@return rop label or {code -1} if {@code bi} was {@code -1}
android/android_framework/dex-maker/src/main/java/com/android/dx/ssa/SsaMethod.java