What this book covers

Chapter 1, LLVM Design and Use, introduces the modular world of LLVM infrastructure, where you learn how to download and install LLVM and Clang. In this chapter, we play with some examples to get accustomed to the workings of LLVM. We also see some examples of various frontends.

Chapter 2, Steps in Writing a Frontend, explains the steps to write a frontend for a language. We will write a bare-metal toy compiler frontend for a basic toy language. We will also see how a frontend language can be converted into the LLVM intermediate representation (IR).

Chapter 3, Extending the Frontend and Adding JIT Support, explores the more advanced features of the toy language and the addition of JIT support to the frontend. We implement some powerful features of a language that are found in most modern programming languages.

Chapter 4, Preparing Optimizations, takes a look at the pass infrastructure of the LLVM IR. We explore various optimization levels, and the optimization techniques kicking at each level. We also see a step-by-step approach to writing our own LLVM pass.

Chapter 5, Implementing Optimizations, demonstrates how we can implement various common optimization passes on LLVM IR. We also explore some vectorization techniques that are not yet present in the LLVM open source code.

Chapter 6, Target-independent Code Generator, takes us on a journey through the abstract infrastructure of a target-independent code generator. We explore how LLVM IR is converted to Selection DAGs, which are further processed to emit target machine code.

Chapter 7, Optimizing the Machine Code, examines how Selection DAGs are optimized and how target registers are allocated to variables. This chapter also describes various optimization techniques on Selection DAGs as well as various register allocation techniques.

Chapter 8, Writing an LLVM Backend, takes us on a journey of describing a target architecture. This chapter covers how to describe registers, instruction sets, calling conventions, encoding, subtarget features, and so on.

Chapter 9, Using LLVM for Various Useful Projects, explores various other projects where LLVM IR infrastructure can be used. Remember that LLVM is not just a compiler; it is a compiler infrastructure. This chapter explores various projects that can be applied to a code snippet to get useful information from it.