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 608 pages

Edition 1st Edition

Languages

C++

Tools

LLVM

Concepts

Programming Language

Author (1):

Quentin Colombet

View More author details

Table of Contents (29) Chapters

Preface

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. 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. Introduction to the Backend

14. Getting Started with the Backend

15. Getting Started with the Machine Code Layer

16. The Machine Pass Pipeline

17. 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. Final Lowering and Optimizations

23. Instruction Scheduling

24. Register Allocation

25. Lowering of the Stack Layout

26. Getting Started with the Assembler

27. Other Books You May Enjoy

28. Index

Writing a simple constant propagation optimization

To help you master LLVM APIs, this section offers a hands-on exercise where you will implement your own constant propagation optimization at the LLVM IR level.

To be able to complete this exercise, you will have to take a closer look at the APIs of the classes that we introduced earlier, mainly the Module, Function, BasicBlock, and Instruction classes, but believe it or not, you have been exposed to almost everything you need to be able to do that.

A possible solution is given in ch4/simple_constant_propagation, and the README.md file in this directory explains how to use your implementation in the provided framework.

Before we give you the few APIs that you need to complete this exercise, let us introduce the problem properly.

The optimization

The constant propagation optimization is as simple as it sounds: you find constant values in your programs, and you try to form more constants by simulating the computations...