LLVM and API reference documentation.

API Reference

Doxygen generated documentation


How To Use Attributes

Answers some questions about the new Attributes infrastructure.

LLVM Reference

Command Line Utilities

LLVM Command Guide

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

LLVM bugpoint tool: design and usage

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

Using -opt-bisect-limit to debug optimization errors

A command line option for debugging optimization-induced failures.

Symbolizer Markup Format

A reference for the log symbolizer markup accepted by llvm-symbolizer.

The Microsoft PDB File Format

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

Garbage Collection

Garbage Collection with LLVM

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

Garbage Collection Safepoints in LLVM

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


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.


LLVM Language Reference Manual

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

Design and Usage of the InAlloca Attribute

Description of the inalloca argument attribute.

LLVM Bitcode File Format

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

Machine IR (MIR) Format Reference Manual

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

Global Instruction Selection

This describes the prototype instruction selection replacement, GlobalISel.

Testing and Debugging

LLVM Testing Infrastructure Guide

A reference manual for using the LLVM testing infrastructure.

test-suite Guide

Describes how to compile and run the test-suite benchmarks.


A sampled heap memory error detection toolkit designed for production use.


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.

Additional Topics

FaultMaps and implicit checks

LLVM support for folding control flow into faulting machine instructions.

LLVM Atomic Instructions and Concurrency Guide

Information about LLVM’s concurrency model.

Exception Handling in LLVM

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

LLVM Extensions

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

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.

LLVM Block Frequency Terminology

Provides information about terminology used in the BlockFrequencyInfo analysis pass.

LLVM Branch Weight Metadata

Provides information about Branch Prediction Information.

The Often Misunderstood GEP Instruction

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

Scudo Hardened Allocator

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


Security hardening for production code aiming to mitigate memory related vulnerabilities. Based on the Armv8.5-A Memory Tagging Extension.

Dependence Graphs

A description of the design of the various dependence graphs such as the DDG (Data Dependence Graph).

Speculative Load Hardening

A description of the Speculative Load Hardening mitigation for Spectre v1.

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.

Stack maps and patch points in LLVM

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

Coroutines in LLVM

LLVM support for coroutines.

Pointer Authentication

A description of pointer authentication, its LLVM IR representation, and its support in the backend.


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

Convergence And Uniformity

A description of uniformity analysis in the presence of irreducible control flow, and its implementation.