Thank you very much for your answer, i will further explore it.
By the way, apart from the tutorial "A CIL Tutorial ..." posted by Zachary Anderson several months ago and the CIL documentation itself,
is there any available documentation which can help me understand the data flow analysis module?
Because i wish to use it do some interprocedural def-use pair analysis.
Best Regards!

Ting SU,software institute,East China Normal University
PhD. student (Email,MSN)
From: Gabriel Kerneis
Date: 2013-03-02 16:59
To: tsuletgo
CC: cil-users
Subject: Re: [CIL users] Can the Reaching Definition Module handle interprocedural def-use analysis?
On Sat, Mar 02, 2013 at 09:29:25AM +0800, tsuletgo wrote:
> I have a question about the Reaching Definition module based on the Data Flow module in CIL.
> Can the RD(Reaching Definition) module analyzes interprocedural def-use pair
> of a variable? or it only can do intraprocedural def-use pair analysis?
After looking at the code briefly, I believe it does only intraprocedural
analysis (but I've never used it myself, and the code is rather complex, so
take this answer with a grain of salt).