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

Generating a parser and lexer with bison and flex

Manually constructing a lexer and a parser is not difficult and usually results in fast components. The disadvantage is that it is not easy to introduce changes, especially in the parser. This can be important if you are prototyping a new programming language. Using specialized tools can mitigate this issue.

There are many tools available that generate either a lexer or a parser from a specification file. In the Linux world, flex ( and bison ( are the most commonly used tools. Flex generates a lexer from a set of regular expressions, while bison generates a parser from a grammar description. Usually, both tools are used together.

Bison produces an LALR(1) parser from a grammar description. An LALR(1) parser is a bottom-up parser and is implemented using an automaton. The input for bison is a grammar file very similar to the one presented at beginning of this chapter...