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

Assembling with the LLVM infrastructure

The LLVM infrastructure uses the same overall pipeline for producing both textual assembly files and object files.

In both cases, the process is guided by your target-specific AsmPrinter pass, which you wrote in Chapter 12. What changes to produce the different types of files is the actual implementation of the MCStreamer class. Figure 21.2 captures this difference:

Figure 21.2: How the target-specific AsmPrinter class produces a textual assembly or binary file

In Figure 21.2, you can see that the abstract MCStreamer class is instantiated with the MCAsmStreamer subclass to produce a textual assembly file (.s) or with one of the MCObjectStreamer subclasses to produce the related binary file format (.o): the MCELFStreamer class for ELF, the MCXCoffStreamer class for COFF, and so on.

The subclasses of the MCObjectStreamer class encapsulate all the logic to produce the layout of the related object file format, including the...