Book Image

Learn LLVM 12

By : Kai Nacke
Book Image

Learn LLVM 12

By: Kai Nacke

Overview of this book

LLVM was built to bridge the gap between compiler textbooks and actual compiler development. It provides a modular codebase and advanced tools which help developers to build compilers easily. This book provides a practical introduction to LLVM, gradually helping you navigate through complex scenarios with ease when it comes to building and working with compilers. You’ll start by configuring, building, and installing LLVM libraries, tools, and external projects. Next, the book will introduce you to LLVM design and how it works in practice during each LLVM compiler stage: frontend, optimizer, and backend. Using a subset of a real programming language as an example, you will then learn how to develop a frontend and generate LLVM IR, hand it over to the optimization pipeline, and generate machine code from it. Later chapters will show you how to extend LLVM with a new pass and how instruction selection in LLVM works. You’ll also focus on Just-in-Time compilation issues and the current state of JIT-compilation support that LLVM provides, before finally going on to understand how to develop a new backend for LLVM. By the end of this LLVM book, you will have gained real-world experience in working with the LLVM compiler development framework with the help of hands-on examples and source code snippets.
Table of Contents (17 chapters)
Section 1 – The Basics of Compiler Construction with LLVM
Section 2 – From Source to Machine Code Generation
Section 3 –Taking LLVM to the Next Level

Piecing it all together

Our new target, located in the llvm/lib/Target/M88k directory, needs to be integrated into the build system. To make development easy, we add it as an experimental target in the llvm/CMakeLists.txt file. We replace the existing empty string with the name of our target:


We also need to provide a llvm/lib/Target/M88k/CMakeLists.txt file to build our target. Besides listing the C++ files for the target, it also defines the generation of the source from the target description.

Generating all the types of sources from the target description

Different runs of the llvm-tblgen tool generate different portions of C++ code. However, I recommend adding the generation of all parts to the CMakeLists.txt file. The reason for this is that it provides better checking. For example, if you make an error with the instruction encoding, then this is only caught during the generation of the...