private int totalRopWidth(RegisterSpecList sources) {
    int sz = sources.size();
    int total = 0;

    for (int i = 0; i < sz; i++) {
      total += sources.get(i).getCategory();
    }

    return total;
  }
Calculates the total rop width of the list of SSA registers

@param sources {@code non-null;} list of SSA registers
@return {@code >= 0;} rop-form width in register units
android/android_framework/dex-maker/src/main/java/com/android/dx/rop/code/DexTranslationAdvice.java