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

[周书林 via llvm-dev]

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 !