Technical requirements

At the time of writing this book, LLVM only has a few software requirements:

• A C/C++ compiler that supports C++14
• CMake
• One of the build systems supported by CMake, such as GNU Make or Ninja
• Python (2.7 is fine too, but I strongly recommend using 3.x)
• zlib

The exact versions of these items change from time to time. Check out https://llvm.org/docs/GettingStarted.html#software for more details.

This chapter assumes you have built an LLVM before. If that's not the case, perform the following steps:

1. Grab a copy of the LLVM source tree from GitHub:

   $ git clone https://github.com/llvm/llvm-project

2. Usually, the default branch should build without errors. If you want to use release versions that are more stable, such as release version 10.x, use the following command:

   $ git clone -b release/10.x https://github.com/llvm/llvm-project

3. Finally, you should create a build folder where you're going to invoke the CMake command. All the building artifacts will also be placed inside this folder. This can be done using the following command:

   $ mkdir .my_build
   $ cd .my_build