public BasicBlock labelToBlock(int label) {
    int idx = indexOfLabel(label);

    if (idx < 0) {
      throw new IllegalArgumentException("no such label: " + Hex.u2(label));
    }

    return get(idx);
  }
Gets the first block in the list with the given label, if any.

@param label {@code label >= 0;} the label to look for
@return {@code non-null;} the so-labelled block
@throws IllegalArgumentException thrown if the label isn't found
android/android_framework/dex-maker/src/main/java/com/android/dx/rop/code/BasicBlockList.java