Explore the world of code generation with the LLVM infrastructure, and learn how to extend existing backends or develop your own Key Features Understand the steps involved in generating assembly code from LLVM IR Learn the key constructs needed to leverage LLVM for your hardware or backend Strengthen your understanding with targeted exercises and practical examples in every chapter Purchase of the print or Kindle book includes a free PDF eBook Book DescriptionThe LLVM infrastructure is a popular compiler ecosystem widely used in the tech industry and academia. This technology is crucial for both experienced and aspiring compiler developers looking to make an impact in the field. Written by Quentin Colombet, a veteran LLVM contributor and architect of the GlobalISel framework, this book provides a primer on the main aspects of LLVM, with an emphasis on its backend infrastructure; that is, everything needed to transform the intermediate representation (IR) produced by frontends like Clang into assembly code and object files. You’ll learn how to write an optimizing code generator for a toy backend in LLVM. The chapters will guide you step by step through building this backend while exploring key concepts, such as the ABI, cost model, and register allocation. You’ll also find out how to express these concepts using LLVM's existing infrastructure and how established backends address these challenges. Furthermore, the book features code snippets that demonstrate the actual APIs. By the end of this book, you’ll have gained a deeper understanding of LLVM. The concepts presented are expected to remain stable across different LLVM versions, making this book a reliable quick reference guide for understanding LLVM.What you will learn Understand essential compiler concepts, such as SSA, dominance, and ABI Build and extend LLVM backends for creating custom compiler features Optimize code by manipulating LLVM's Intermediate Representation Contribute effectively to LLVM open-source projects and development Develop debugging skills for LLVM optimizations and passes Grasp how encoding and (dis)assembling work in the context of compilers Utilize LLVM's TableGen DSL for creating custom compiler models Who this book is forThis book is for both beginners to LLVM and experienced LLVM developers. If you’re new to LLVM, it offers a clear, approachable guide to compiler backends, starting with foundational concepts. For seasoned LLVM developers, it dives into less-documented areas such as TableGen, MachineIR, and MC, enabling you to solve complex problems and expand your expertise. Whether you’re starting out or looking to deepen your knowledge, this book has something for you.

Table of Contents:
Table of Contents Building LLVM, Understanding the Directory Structure Compiler Basics and How They Map to LLVM Structures Dealing with the Pass Pipeline TableGen: LLVM's Swiss Army Knife for Modeling Understanding LLVM IR Survey of the Existing Passes Introducing Target-Specific Constructs - Custom Passes, Intrinsic, Cost Model Hands-On Debugging LLVM IR Passes Understanding MachineIR Machine Pass Pipeline - Hypothesis, Optimizations, and Target Hooks Legacy Instruction Selection Framework - SelectionDAG The New Instruction Selection Framework - GlobalISel Instruction Scheduling - Data Dependency Graph and Scheduling Model Register Allocation - Coalescing, Spilling, and Register Assignment Hands-On Debugging MachineIR Passes Understanding MC Building the Assembler - Disassembler Running Analysis on the MC Layer Register Allocation Lowering of the Stack Layout Assembler