public void mergeInterferenceSet(int reg, IntSet set) {
    if (reg < interference.size()) {
      set.merge(interference.get(reg));
    }
  }
Merges the interference set for a register into a given bit set

@param reg {@code >= 0;} register
@param set {@code non-null;} interference set; will be merged with set for given register
android/android_framework/dex-maker/src/main/java/com/android/dx/ssa/back/InterferenceGraph.java