public void add(int regV, int regW) {
    ensureCapacity(Math.max(regV, regW) + 1);

    interference.get(regV).add(regW);
    interference.get(regW).add(regV);
  }
Adds a register pair to the interference/liveness graph. Parameter order is insignificant.

@param regV one register index
@param regW another register index
android/android_framework/dex-maker/src/main/java/com/android/dx/ssa/back/InterferenceGraph.java