[llvm-dev] How to do some dataflow analysis via IR on a large project?

Kevin Hu via llvm-dev llvm-dev at lists.llvm.org
Mon Feb 29 21:55:50 PST 2016

Dear Shulin,

Sounds like you'll need an inter-procedural analysis across different
source files. One
option I can think of is to manually update the Makefiles, make compiler
emit bitcode
files, merge them with llvm-link and run it through your optimization pass
as a big bitcode
file. This somehow could involve huge amount of tedious work for a huge
project like
Apache, and may be error-prone.

Another option I can think of is the libLTO. It should link all bitcode
files and run optimization
passes for you.


I've never dealt with it myself and I don't find abundant tutorials and
examples online. You
probably need to dig into the source code. (in lib/LTO ?)

Correct me where I'm wrong or if there are any other good approaches.


On Mon, Feb 29, 2016 at 9:15 PM 周书林 via llvm-dev <llvm-dev at lists.llvm.org>

> I am learning to do some basic dataflow analysis on C code projects,
> such as Apache httpd. Now I am a newbie of LLVM IR, and there are some
> problems in doing that.
> In the official User Manual of how to write a LLVM PASS, they only
> show the way to generate IR of a single ".c" source file. But in fact
> there are so many examples that the usage and definition of a function
> are not in the same ".c" source file, rising the difficulty of
> analzing the dataflow of such functions.
> So, I want to know, is there any method of strategies to generate the
> IR among many related source files?
> Thanks a lot !
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
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