giserman / llvm6-pass-template

An easy to use template for building an LLVM 6 sample pass

At a glance

A step-by-step tutorial for building an out-of-source LLVM pass based on Adrian Sampson's "LLVM for Grad Students"

Setup

LLVM is an umbrella project for building compilers and code transformation tools. We consider in this tutorial:

• Building LLVM from source
• Building a trivial out-of-source LLVM pass.

We will be building LLVM v6.0.1 which is the latest as of this writing. We assume that you have a working compiler toolchain (GCC or LLVM) and that CMake is installed (minimum version 3.4.3). We also assume that you are working un a Linux system.

With a working Internet connection, run ./setup.sh and pray the Linux Gods that nothing fails. This will download LLVM and clang and then compile them.

Building the Pass

Run ./build.sh.

This will basically create ./build/ and run cmake on it.

Testing the Pass

Run ./test.sh.

This will compile ./test/test.c into human-readable LLVM IR, run the pass on it and show the final IR.

Further resources

This tutorial is based on the following resources

• Adrian Sampson's blog entry "LLVM for Grad Students" (link)
• LLVM documentation: Writing an LLVM pass (link)
• LLVM documentation: Building LLVM with CMake (link)