public DalvInsn expandedSuffix(BitSet compatRegs) {
    if (hasResult() && !compatRegs.get(0)) {
      RegisterSpec r = registers.get(0);
      return makeMove(position, r, r.withReg(0));
    } else {
      return null;
    }
  }
Gets the instruction suffix required, if any, to use in an expanded version of this instance.
Will not generate a move for a register marked compatible to the format by the given BitSet.

@param compatRegs {@code non-null;} set of compatible registers
@return {@code null-ok;} the suffix, if any
@see #expandedVersion
android/android_framework/dex-maker/src/main/java/com/android/dx/dex/code/DalvInsn.java