[LLVMdev] How to slice the source code?

[Jonas Wagner]

Hi,

maybe you can have a look at the CReduce project:
http://embed.cs.utah.edu/creduce/

This project implements many source-to-source transformations of C
programs, e.g. removing functions, changing variable names, deleting
branches in if-statements, etc. Some of these are purely based on the
source code, other use the Clang frontend.

Hope this helps,
Jonas


On Sun, Mar 17, 2013 at 7:25 PM, Mingliang LIU <liuml07 at gmail.com> wrote:

> Hi all,
>
> I'm doing the program slicing [1] in LLVM. Now I implemented the Weiser's
> algorithm [2] in a simple way by writing a plugin to analyze the IR. My
> final goal is to slice the source code, thus I recorded all the lines of
> source code to be sliced. The last step is to delete the lines which are
> not in the program slice. However, I met a problem when deleting the source
> code directly:
>
> To make it clear, I gave an example following, in which the following
> lines (underline decoration) can be deleted. We can see that the line 4
> should also be deleted, but it's not.
>
>> 1   *for (int i = 0; i < BUFSIZE; i++) {*
>> 2      *for (int j = 0; j < np; j++)
>> *3         *buf[i] = ((rank + j) % np);
>> *4  }
>
>
> I got the LoC info from meta-data of the IR which can be deleted. However,
> there is no according IR in the first place, which represents the line 4
> (whose functionality is to end a block). I'm not familiar with clang and
> its AST. A friend told me to parse the code using python to find the
> matching "}" (or END in Fortran) and delete them. I'd like to know if there
> is an LLVM way to do this.
>
> Any idea?
>
> Thank you!
>
> [1] http://en.wikipedia.org/wiki/Program_slicing
> [2] http://dl.acm.org/citation.cfm?id=802557
> --
> Mingliang LIU (刘明亮 in Chinese)
>
> PACMAN Group,  Dept. of Computer Science & Technology
> Tsinghua University, Beijing 100084, China
> Email: liuml07 at mails.tsinghua.edu.cn
> Homepage: http://pacman.cs.tsinghua.edu.cn/~liuml07/
>
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>
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