You're reading from LLVM Code Generation A deep dive into compiler backend development

Product type Paperback

Published in May 2025

Publisher Packt

ISBN-13 9781837637782

Length 620 pages

Edition 1st Edition

Languages

C++

Tools

LLVM

Concepts

Programming Language

Author (1):

Quentin Colombet

View More author details

Table of Contents (30) Chapters

Preface

1. Part 1: Getting Started with LLVM

2. Building LLVM and Understanding the Directory Structure FREE CHAPTER

3. Contributing to LLVM

4. Compiler Basics and How They Map to LLVM APIs

5. Writing Your First Optimization

6. Dealing with Pass Managers

7. TableGen – LLVM Swiss Army Knife for Modeling

8. Part 2: Middle-End: LLVM IR to LLVM IR

9. Understanding LLVM IR

10. Survey of the Existing Passes

11. Introducing Target-Specific Constructs

12. Hands-On Debugging LLVM IR Passes

13. Part 3: Introduction to the Backend

14. Getting Started with the Backend

15. Getting Started with the Machine Code Layer

16. The Machine Pass Pipeline

17. Part 4: LLVM IR to Machine IR

18. Getting Started with Instruction Selection

19. Instruction Selection: The IR Building Phase

20. Instruction Selection: The Legalization Phase

21. Instruction Selection: The Selection Phase and Beyond

22. Part 5: Final Lowering and Optimizations

23. Instruction Scheduling

24. Register Allocation

25. Lowering of the Stack Layout

26. Getting Started with the Assembler

27. Unlock Your Book’s Exclusive Benefits

28. Other Books You May Enjoy

29. Index

How to find the unknown

If we told you to look for a specific transformation, you would find it by looking for some keywords across the code base (using git grep, for instance). However, if you do not know what exists in the middle end, how do you even begin to look for it?

In this section, you will discover two main ways to approach the LLVM code base to find what it has to offer. This information is important as it allows you to reuse what exists instead of reimplementing everything.

The first approach leverages opt, an LLVM-provided developer tool, to present human-friendly information. We will show you how to dig into the code base using that information.

In the second approach, we flip the angle of attack by starting from the source files instead of the developer-facing tools. You will discover what to expect in each directory and how to extract the relevant information from the source files.