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

The logging capabilities in LLVM

One of the nice things that you get for almost free when building components with the LLVM infrastructure is its logging capabilities.

You can use this feature as soon as you’ve hooked up the LLVM command-line interface (CLI) in your compiler (see Chapter 5 on how to do this). The opt developer tool, which you can build within the LLVM project and Clang, is set up to expose these logging capabilities.

Let’s start with the first class of logging that you can enable: intermediate dumps.

Printing the IR between passes

The pass managers expose command-line options to print the IR before and after each pass using the textual representation. You can use the following options to enable this printing:

print-before-all/print-after-all: Print the IR before (or after, respectively) each pass in the current pipeline.
print-before/print-after=PassName1[,PassName2]*: Print the IR before (or after, respectively) PassName1...