The LLVM compiler infrastructure supports a wide range of projects, from industrial strength compilers to specialized JIT applications to small research projects.

Similarly, documentation is broken down into several high-level groupings targeted at different audiences:

LLVM Design & Overview

Several introductory papers and presentations.

LLVM Language Reference Manual

Defines the LLVM intermediate representation.

Introduction to the LLVM Compiler

Presentation providing a users introduction to LLVM.

Intro to LLVM

Book chapter providing a compiler hacker’s introduction to LLVM.

LLVM: A Compilation Framework for Lifelong Program Analysis & Transformation

Design overview.

LLVM: An Infrastructure for Multi-Stage Optimization

More details (quite old now).

Publications mentioning LLVM

User Guides

For those new to the LLVM system.

NOTE: If you are a user who is only interested in using LLVM-based compilers, you should look into Clang or DragonEgg instead. The documentation here is intended for users who have a need to work with the intermediate LLVM representation.

Getting Started with the LLVM System

Discusses how to get up and running quickly with the LLVM infrastructure. Everything from unpacking and compilation of the distribution to execution of some tools.

Building LLVM with CMake

An addendum to the main Getting Started guide for those using the CMake build system.

How To Build On ARM

Notes on building and testing LLVM/Clang on ARM.

How to Cross Compile Compiler-rt Builtins For Arm

Notes on cross-building and testing the compiler-rt builtins for Arm.

How To Cross-Compile Clang/LLVM using Clang/LLVM

Notes on cross-building and testing LLVM/Clang.

Getting Started with the LLVM System using Microsoft Visual Studio

An addendum to the main Getting Started guide for those using Visual Studio on Windows.

LLVM Tutorial: Table of Contents

Tutorials about using LLVM. Includes a tutorial about making a custom language with LLVM.

LLVM Command Guide

A reference manual for the LLVM command line utilities (“man” pages for LLVM tools).

LLVM’s Analysis and Transform Passes

A list of optimizations and analyses implemented in LLVM.

Frequently Asked Questions (FAQ)

A list of common questions and problems and their solutions.

Release notes for the current release

This describes new features, known bugs, and other limitations.

How to submit an LLVM bug report

Instructions for properly submitting information about any bugs you run into in the LLVM system.

Sphinx Quickstart Template

A template + tutorial for writing new Sphinx documentation. It is meant to be read in source form.

LLVM Testing Infrastructure Guide

A reference manual for using the LLVM testing infrastructure.

How to build the C, C++, ObjC, and ObjC++ front end

Instructions for building the clang front-end from source.

The LLVM Lexicon

Definition of acronyms, terms and concepts used in LLVM.

How To Add Your Build Configuration To LLVM Buildbot Infrastructure

Instructions for adding new builder to LLVM buildbot master.


A reference guide for using LLVM’s YAML I/O library.

The Often Misunderstood GEP Instruction

Answers to some very frequent questions about LLVM’s most frequently misunderstood instruction.

Performance Tips for Frontend Authors

A collection of tips for frontend authors on how to generate IR which LLVM is able to effectively optimize.

A guide to Dockerfiles for building LLVM

A reference for using Dockerfiles provided with LLVM.

Programming Documentation

For developers of applications which use LLVM as a library.

LLVM Language Reference Manual

Defines the LLVM intermediate representation and the assembly form of the different nodes.

LLVM Atomic Instructions and Concurrency Guide

Information about LLVM’s concurrency model.

LLVM Programmer’s Manual

Introduction to the general layout of the LLVM sourcebase, important classes and APIs, and some tips & tricks.

LLVM Extensions

LLVM-specific extensions to tools and formats LLVM seeks compatibility with.

CommandLine 2.0 Library Manual

Provides information on using the command line parsing library.

LLVM Coding Standards

Details the LLVM coding standards and provides useful information on writing efficient C++ code.

How to set up LLVM-style RTTI for your class hierarchy

How to make isa<>, dyn_cast<>, etc. available for clients of your class hierarchy.

Extending LLVM: Adding instructions, intrinsics, types, etc.

Look here to see how to add instructions and intrinsics to LLVM.

Doxygen generated documentation


Documentation for Go bindings

ViewVC Repository Browser
Architecture & Platform Information for Compiler Writers

A list of helpful links for compiler writers.

libFuzzer – a library for coverage-guided fuzz testing.

A library for writing in-process guided fuzzers.

Fuzzing LLVM libraries and tools

Information on writing and using Fuzzers to find bugs in LLVM.

Scudo Hardened Allocator

A library that implements a security-hardened malloc().

Using -opt-bisect-limit to debug optimization errors

A command line option for debugging optimization-induced failures.

Subsystem Documentation

For API clients and LLVM developers.

Writing an LLVM Pass

Information on how to write LLVM transformations and analyses.

Writing an LLVM Backend

Information on how to write LLVM backends for machine targets.

The LLVM Target-Independent Code Generator

The design and implementation of the LLVM code generator. Useful if you are working on retargetting LLVM to a new architecture, designing a new codegen pass, or enhancing existing components.

Machine IR (MIR) Format Reference Manual

A reference manual for the MIR serialization format, which is used to test LLVM’s code generation passes.


Describes the TableGen tool, which is used heavily by the LLVM code generator.

LLVM Alias Analysis Infrastructure

Information on how to write a new alias analysis implementation or how to use existing analyses.


Information about the MemorySSA utility in LLVM, as well as how to use it.

Garbage Collection with LLVM

The interfaces source-language compilers should use for compiling GC’d programs.

Source Level Debugging with LLVM

This document describes the design and philosophy behind the LLVM source-level debugger.

Auto-Vectorization in LLVM

This document describes the current status of vectorization in LLVM.

Exception Handling in LLVM

This document describes the design and implementation of exception handling in LLVM.

LLVM bugpoint tool: design and usage

Automatic bug finder and test-case reducer description and usage information.

LLVM Bitcode File Format

This describes the file format and encoding used for LLVM “bc” files.

System Library

This document describes the LLVM System Library (lib/System) and how to keep LLVM source code portable

LLVM Link Time Optimization: Design and Implementation

This document describes the interface between LLVM intermodular optimizer and the linker and its design

The LLVM gold plugin

How to build your programs with link-time optimization on Linux.

Debugging JIT-ed Code With GDB

How to debug JITed code with GDB.

MCJIT Design and Implementation

Describes the inner workings of MCJIT execution engine.

LLVM Branch Weight Metadata

Provides information about Branch Prediction Information.

LLVM Block Frequency Terminology

Provides information about terminology used in the BlockFrequencyInfo analysis pass.

Segmented Stacks in LLVM

This document describes segmented stacks and how they are used in LLVM.

LLVM’s Optional Rich Disassembly Output

This document describes the optional rich disassembly output syntax.

How To Use Attributes

Answers some questions about the new Attributes infrastructure.

User Guide for NVPTX Back-end

This document describes using the NVPTX backend to compile GPU kernels.

User Guide for AMDGPU Backend

This document describes using the AMDGPU backend to compile GPU kernels.

Stack maps and patch points in LLVM

LLVM support for mapping instruction addresses to the location of values and allowing code to be patched.

Using ARM NEON instructions in big endian mode

LLVM’s support for generating NEON instructions on big endian ARM targets is somewhat nonintuitive. This document explains the implementation and rationale.

LLVM Code Coverage Mapping Format

This describes the format and encoding used for LLVM’s code coverage mapping.

Garbage Collection Safepoints in LLVM

This describes a set of experimental extensions for garbage collection support.

MergeFunctions pass, how it works

Describes functions merging optimization.

Design and Usage of the InAlloca Attribute

Description of the inalloca argument attribute.

FaultMaps and implicit checks

LLVM support for folding control flow into faulting machine instructions.

Compiling CUDA with clang

LLVM support for CUDA.

Coroutines in LLVM

LLVM support for coroutines.

Global Instruction Selection

This describes the prototype instruction selection replacement, GlobalISel.

XRay Instrumentation

High-level documentation of how to use XRay in LLVM.

Debugging with XRay

An example of how to debug an application with XRay.

The Microsoft PDB File Format

A detailed description of the Microsoft PDB (Program Database) file format.

Control Flow Verification Tool Design Document

A description of the verification tool for Control Flow Integrity.

Development Process Documentation

Information about LLVM’s development process.

Contributing to LLVM

An overview on how to contribute to LLVM.

LLVM Developer Policy

The LLVM project’s policy towards developers and their contributions.

Creating an LLVM Project

How-to guide and templates for new projects that use the LLVM infrastructure. The templates (directory organization, Makefiles, and test tree) allow the project code to be located outside (or inside) the llvm/ tree, while using LLVM header files and libraries.

LLVMBuild Guide

Describes the LLVMBuild organization and files used by LLVM to specify component descriptions.

How To Release LLVM To The Public

This is a guide to preparing LLVM releases. Most developers can ignore it.

How To Validate a New Release

This is a guide to validate a new release, during the release process. Most developers can ignore it.

Advice on Packaging LLVM

Advice on packaging LLVM into a distribution.

Code Reviews with Phabricator

Describes how to use the Phabricator code review tool hosted on http://reviews.llvm.org/ and its command line interface, Arcanist.


LLVM has a thriving community of friendly and helpful developers. The two primary communication mechanisms in the LLVM community are mailing lists and IRC.

Mailing Lists

If you can’t find what you need in these docs, try consulting the mailing lists.

Developer’s List (llvm-dev)

This list is for people who want to be included in technical discussions of LLVM. People post to this list when they have questions about writing code for or using the LLVM tools. It is relatively low volume.

Commits Archive (llvm-commits)

This list contains all commit messages that are made when LLVM developers commit code changes to the repository. It also serves as a forum for patch review (i.e. send patches here). It is useful for those who want to stay on the bleeding edge of LLVM development. This list is very high volume.

Bugs & Patches Archive (llvm-bugs)

This list gets emailed every time a bug is opened and closed. It is higher volume than the LLVM-dev list.

Test Results Archive (llvm-testresults)

A message is automatically sent to this list by every active nightly tester when it completes. As such, this list gets email several times each day, making it a high volume list.

LLVM Announcements List (llvm-announce)

This is a low volume list that provides important announcements regarding LLVM. It gets email about once a month.


Users and developers of the LLVM project (including subprojects such as Clang) can be found in #llvm on irc.oftc.net.

This channel has several bots.

  • Buildbot reporters

  • robot - Bugzilla linker. %bug <number>

  • clang-bot - A geordi instance running near-trunk clang instead of gcc.

Community wide proposals

Proposals for massive changes in how the community behaves and how the work flow can be better.

LLVM Community Code of Conduct

Proposal to adopt a code of conduct on the LLVM social spaces (lists, events, IRC, etc).

Moving LLVM Projects to GitHub

Proposal to move from SVN/Git to GitHub.

Vectorization Plan

Proposal to model the process and upgrade the infrastructure of LLVM’s Loop Vectorizer.

Indices and tables