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

Instrumenting an application with sanitizers

LLVM comes with a couple of sanitizers. These are passes that instrument the Intermediate Representation (IR) in a way to check for certain misbehaviors of an application. Usually, they require library support, which is part of the compiler-rt project. Sanitizers can be enabled in Clang, which makes them very comfortable to use. In the following sections, we will have a look at the available sanitizers, namely, address, memory, and thread. We will first look at the address sanitizer.

Detecting memory access problems with the address sanitizer

You use the address sanitizer to detect a couple of memory access bugs in an application. This includes common errors such as using dynamically allocated memory after freeing it, or writing to dynamically allocated memory outside the boundaries of the allocated memory.

When enabled, the address sanitizer replaces calls to the malloc() and free() functions with its own version, and instruments...