Getting Started with LLVM Core Libraries

Bruno Cardoso Lopes, Rafael Auler

• Publisher: Packt Publishing
• Year: 2014
• ISBN:
  9781782166924
• Edition: 1
• Topic: Ciencia de la computación
• Subtopic: Programación en C++

LLVM is a bleeding edge compiler technology framework. Easily extendable and designed as a multitude of libraries, LLVM provides a smooth experience for compiler newcomers and reduces the steep learning curve often associated with compiler development.

To start, this book will show you how to configure, build, and install LLVM libraries, tools, and external projects. Next, you will be introduced to LLVM design and how it works in practice throughout each LLVM compiler stage: frontend, IR, backend, the JIT engine, cross-compilation capabilities, and the plugin interface. With multiple hands-on examples and source code snippets, Getting Started with LLVM Core Libraries ensures a solid and smooth  first step into the LLVM compiler development environment.

Getting Started with LLVM Core Libraries

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Table of Contents

Getting Started with LLVM Core Libraries

Credits

About the Authors

About the Reviewers

www.PacktPub.com

Support files, eBooks, discount offers, and more

Why subscribe?

Free access for Packt account holders

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. Build and Install LLVM

Understanding LLVM versions

Obtaining prebuilt packages

Obtaining the official prebuilt binaries

Using package managers

Staying updated with snapshot packages

Linux

Windows

Building from sources

System requirements

Obtaining sources

SVN

Git

Building and installing LLVM

Using the autotools-generated configure script

Building and configuring with Unix

Using CMake and Ninja

Building with Unix using CMake and Ninja

Solving build errors

Using other Unix approaches

Windows and Microsoft Visual Studio

Mac OS X and Xcode

Summary

2. External Projects

Introducing Clang extras

Building and installing Clang extra tools

Understanding Compiler-RT

Seeing Compiler-RT in action

Using the DragonEgg plugin

Building DragonEgg

Understanding the compilation pipeline with DragonEgg and LLVM tools

Understanding the LLVM test suite

Using LLDB

Exercising a debug session with LLDB

Introducing the libc++ standard library

Summary

3. Tools and Design

Introducing LLVM's basic design principles and its history

Understanding LLVM today

Interacting with the compiler driver

Using standalone tools

Delving into the LLVM internal design

Getting to know LLVM's basic libraries

Introducing LLVM's C++ practices

Seeing polymorphism in practice

Introducing C++ templates in LLVM

Enforcing C++ best practices in LLVM

Making string references lightweight in LLVM

Demonstrating the pluggable pass interface

Writing your first LLVM project

Writing the Makefile

Writing the code

Navigating the LLVM source – general advice

Understanding the code as a documentation

Asking the community for help

Coping with updates – using the SVN log as a documentation

Concluding remarks

Summary

4. The Frontend

Introducing Clang

Frontend actions

Libraries

Using libclang

Understanding Clang diagnostics

Reading diagnostics

Learning the frontend phases with Clang

Lexical analysis

Exercising lexical errors

Writing libclang code that uses the lexer

Preprocessing

Syntactic analysis

Understanding Clang AST nodes

Understanding the parser actions with a debugger

Exercising a parser error

Writing code that traverses the Clang AST

Serializing the AST with precompiled headers

Semantic analysis

Exercising a semantic error

Generating the LLVM IR code

Putting it together

Summary

5. The LLVM Intermediate Representation

Overview

Understanding the LLVM IR target dependency

Exercising basic tools to manipulate the IR formats

Introducing the LLVM IR language syntax

Introducing the LLVM IR in-memory model

Writing a custom LLVM IR generator

Building and running the IR generator

Learning how to write code to generate any IR construct with the C++ backend

Optimizing at the IR level

Compile-time and link-time optimizations

Discovering which passes matter

Understanding pass dependencies

Understanding the pass API

Writing a custom pass

Building and running your new pass with the LLVM build system

Building and running your new pass with your own Makefile

Summary

6. The Backend

Overview

Using the backend tools

Learning the backend code structure

Knowing the backend libraries

Learning how to use TableGen for LLVM backends

The language

Knowing the code generator .td files

Target properties

Registers

Instructions

Understanding the instruction selection phase

The SelectionDAG class

Lowering

DAG combine and legalization

DAG-to-DAG instruction selection

Pattern matching

Visualizing the instruction selection process

Fast instruction selection

Scheduler

Instruction itineraries

Hazard detection

Scheduling units

Machine instructions

Register allocation

Register coalescer

Virtual register rewrite

Target hooks

Prologue and epilogue

Frame indexes

Understanding the machine code framework

MC instructions

Code emission

Writing your own machine pass

Summary

7. The Just-in-Time Compiler

Getting to know the LLVM JIT engine basics

Introducing the execution engine

Memory management

Introducing the llvm::JIT framework

Writing blobs to memory

Using JITMemoryManager

Target code emitters

Target information

Learning how to use the JIT class

The generic value

Introducing the llvm::MCJIT framework

The MCJIT engine

Learning the module's states

Understanding how MCJIT compiles modules

The Object buffer, the cache, and the image

Dynamic linking

The memory manager

The MC code emission

Object finalization

Using the MCJIT engine

Using LLVM JIT compilation tools

Using the lli tool

Using the llvm-rtdyld tool

Other resources

Summary

8. Cross-platform Compilation

Comparing GCC and LLVM

Understanding target triples

Preparing your toolchain

Standard C and C++ libraries

Runtime libraries

The assembler and the linker

The Clang frontend

Multilib

Cross-compiling with Clang command-line arguments

Driver options for the target

Dependencies

Cross-compiling

Installing GCC

Potential problems

Changing the system root

Generating a Clang cross-compiler

Configuration options

Building and installing your Clang-based cross-compiler

Alternative build methods

Ninja

ELLCC

EmbToolkit

Testing

Development boards

Simulators

Additional resources

Summary

9. The Clang Static Analyzer

Understanding the role of a static analyzer

Comparing classic warnings versus the Clang Static Analyzer

The power of the symbolic execution engine

Testing the static analyzer

Using the driver versus using the compiler

Getting to know the available checkers

Using the static analyzer in the Xcode IDE

Generating graphical reports in HTML

Handling large projects

A real-world example – finding bugs in Apache

Extending the static analyzer with your own checkers

Getting familiar with the project architecture

Writing your own checker

Solving the problem with a custom checker

Writing the state class

Understanding ProgramState immutability

Dissecting the code

Defining the Checker subclass

Writing the Register macro

Implem...