Book Image

Learn LLVM 12

By : Kai Nacke
Book Image

Learn LLVM 12

By: Kai Nacke

Overview of this book

LLVM was built to bridge the gap between compiler textbooks and actual compiler development. It provides a modular codebase and advanced tools which help developers to build compilers easily. This book provides a practical introduction to LLVM, gradually helping you navigate through complex scenarios with ease when it comes to building and working with compilers. You’ll start by configuring, building, and installing LLVM libraries, tools, and external projects. Next, the book will introduce you to LLVM design and how it works in practice during each LLVM compiler stage: frontend, optimizer, and backend. Using a subset of a real programming language as an example, you will then learn how to develop a frontend and generate LLVM IR, hand it over to the optimization pipeline, and generate machine code from it. Later chapters will show you how to extend LLVM with a new pass and how instruction selection in LLVM works. You’ll also focus on Just-in-Time compilation issues and the current state of JIT-compilation support that LLVM provides, before finally going on to understand how to develop a new backend for LLVM. By the end of this LLVM book, you will have gained real-world experience in working with the LLVM compiler development framework with the help of hands-on examples and source code snippets.
Table of Contents (17 chapters)
Section 1 – The Basics of Compiler Construction with LLVM
Section 2 – From Source to Machine Code Generation
Section 3 –Taking LLVM to the Next Level

Creating the project layout

The project layout for tinylang follows the approach we laid out in Chapter 2, Touring the LLVM Source. The source code for each component is in a subdirectory of the lib directory, while the header files are in a subdirectory of include/tinylang. The subdirectory is named after the component. In Chapter 2, Touring the LLVM Source, we only created the Basic component.

From the previous chapter, we know that we need to implement a lexer, a parser, an AST, and a semantic analyzer. Each is a component of its own, called Lexer, Parser, AST, and Sema. The directory layout that was used in the previous chapter looks like this:

Figure 4.1 – The directory layout of the tinylang project

The components have clearly defined dependencies. Here, Lexer only depends on Basic. Parser depends on Basic, Lexer, AST, and Sema. Finally, Sema only depends on Basic and AST. These well-defined dependencies help with reusing components.