private int getParamIndex(NormalSsaInsn insn) {
    CstInsn cstInsn = (CstInsn) (insn.getOriginalRopInsn());

    int param = ((CstInteger) cstInsn.getConstant()).getValue();
    return param;
  }
Returns the parameter index associated with a move-param insn. Does not verify that the insn is
a move-param insn.

@param insn {@code non-null;} a move-param insn
@return {@code >=0;} parameter index
android/android_framework/dex-maker/src/main/java/com/android/dx/ssa/MoveParamCombiner.java