@Override
      int nextClearBit(BitSet bitSet, int startIdx) {
        int bitNumber = bitSet.nextClearBit(startIdx);
        while (isEven(bitNumber)) {
          bitNumber = bitSet.nextClearBit(bitNumber + 1);
        }
        return bitNumber;
      }
Alignment constraint that can be used during search of free registers.
android/android_framework/dex-maker/src/main/java/com/android/dx/ssa/back/FirstFitLocalCombiningAllocator.java