A CIL Tutorial - Department of Computer Science - ETH Zürich

CHAPTER 0. OVERVIEW AND ORGANIZATION 9
modications to it, and optionally returns a result up to the caller in main.ml. We include this
source le in the build by adding it to the list CILTUT SRC in CMakeLists.txt.
Functions, like tut0 below, that do this sort of work should be called from processOneFile in
main.ml.
0.2 tut0.ml
The rst step in writing an OCaml module that uses the CIL library is to open the Cil module (or
bind it to an alias, like we do with the Errormsg module). The CMakeLists.txt le provided with
this tutorial ensures that the CIL library is correctly found and linked assuming that it has been
correctly installed. From now on, in the following chapters, the code to open modules and create
aliases will be included only for the rst mention of a module.
open Cil (∗ The CIL library ∗)
module E = Errormsg (∗ CIL's error message library ∗)
tut0 is a dummy function that doesn't do anything. However, there is certainly nothing preventing
it from inspecting f and making changes to its mutable elds if it really wanted to.
let tut0 (f : file) : unit =
E.log "I'n in tut0 and I could change %s if I wanted to!\n" f.fileName;
()
When the compiler front-end embodied by this tutorial is built and installed, the code in this
module may be run by providing the --enable-tut0 command line switch, like so:
$ ciltutcc --enable-tut0 -o program program.c
I'm in tut0 and I could change program.i if I wanted to!
Finally, if ciltutcc fails due to an unhandled exception, a stack trace may be obtained by
re-executing the command as follows:
OCaml Style Note: Types are inferred, so you don't have to write them
all the time. However, if you want to remember what your code does a month
from now, writing in some of the types is a Good Idea.