Warning
If you are using a released version of LLVM, see the download page to find your documentation.
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:
Several introductory papers and presentations.
.. toctree:: :hidden: LangRef
- :doc:`LangRef`
- 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
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.
.. toctree:: :hidden: CMake HowToBuildOnARM HowToCrossCompileLLVM CommandGuide/index GettingStarted GettingStartedVS BuildingLLVMWithAutotools FAQ Lexicon HowToAddABuilder yaml2obj HowToSubmitABug SphinxQuickstartTemplate Phabricator TestingGuide tutorial/index ReleaseNotes Passes YamlIO GetElementPtr Frontend/PerformanceTips MCJITDesignAndImplementation
- :doc:`GettingStarted`
- 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.
- :doc:`CMake`
- An addendum to the main Getting Started guide for those using the CMake build system.
- :doc:`HowToBuildOnARM`
- Notes on building and testing LLVM/Clang on ARM.
- :doc:`HowToCrossCompileLLVM`
- Notes on cross-building and testing LLVM/Clang.
- :doc:`GettingStartedVS`
- An addendum to the main Getting Started guide for those using Visual Studio on Windows.
- :doc:`BuildingLLVMWithAutotools`
- An addendum to the Getting Started guide with instructions for building LLVM with the Autotools build system.
- :doc:`tutorial/index`
- Tutorials about using LLVM. Includes a tutorial about making a custom language with LLVM.
- :doc:`LLVM Command Guide <CommandGuide/index>`
- A reference manual for the LLVM command line utilities ("man" pages for LLVM tools).
- :doc:`Passes`
- A list of optimizations and analyses implemented in LLVM.
- :doc:`FAQ`
- A list of common questions and problems and their solutions.
- :doc:`Release notes for the current release <ReleaseNotes>`
- This describes new features, known bugs, and other limitations.
- :doc:`HowToSubmitABug`
- Instructions for properly submitting information about any bugs you run into in the LLVM system.
- :doc:`SphinxQuickstartTemplate`
- A template + tutorial for writing new Sphinx documentation. It is meant to be read in source form.
- :doc:`LLVM Testing Infrastructure Guide <TestingGuide>`
- 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.
- :doc:`Lexicon`
- Definition of acronyms, terms and concepts used in LLVM.
- :doc:`HowToAddABuilder`
- Instructions for adding new builder to LLVM buildbot master.
- :doc:`YamlIO`
- A reference guide for using LLVM's YAML I/O library.
- :doc:`GetElementPtr`
- Answers to some very frequent questions about LLVM's most frequently misunderstood instruction.
- :doc:`Frontend/PerformanceTips`
- A collection of tips for frontend authors on how to generate IR which LLVM is able to effectively optimize.
For developers of applications which use LLVM as a library.
.. toctree:: :hidden: Atomics CodingStandards CommandLine CompilerWriterInfo ExtendingLLVM HowToSetUpLLVMStyleRTTI ProgrammersManual Extensions LibFuzzer
- :doc:`LLVM Language Reference Manual <LangRef>`
- Defines the LLVM intermediate representation and the assembly form of the different nodes.
- :doc:`Atomics`
- Information about LLVM's concurrency model.
- :doc:`ProgrammersManual`
- Introduction to the general layout of the LLVM sourcebase, important classes and APIs, and some tips & tricks.
- :doc:`Extensions`
- LLVM-specific extensions to tools and formats LLVM seeks compatibility with.
- :doc:`CommandLine`
- Provides information on using the command line parsing library.
- :doc:`CodingStandards`
- Details the LLVM coding standards and provides useful information on writing efficient C++ code.
- :doc:`HowToSetUpLLVMStyleRTTI`
- How to make
isa<>,dyn_cast<>, etc. available for clients of your class hierarchy. - :doc:`ExtendingLLVM`
- Look here to see how to add instructions and intrinsics to LLVM.
- Doxygen generated documentation
- (classes) (tarball)
- ViewVC Repository Browser
- :doc:`CompilerWriterInfo`
- A list of helpful links for compiler writers.
- :doc:`LibFuzzer`
- A library for writing in-process guided fuzzers.
For API clients and LLVM developers.
.. toctree:: :hidden: AliasAnalysis BitCodeFormat BlockFrequencyTerminology BranchWeightMetadata Bugpoint CodeGenerator ExceptionHandling LinkTimeOptimization SegmentedStacks TableGenFundamentals TableGen/index DebuggingJITedCode GoldPlugin MarkedUpDisassembly SystemLibrary SourceLevelDebugging Vectorizers WritingAnLLVMBackend GarbageCollection WritingAnLLVMPass HowToUseAttributes NVPTXUsage AMDGPUUsage StackMaps InAlloca BigEndianNEON CoverageMappingFormat Statepoints MergeFunctions BitSets FaultMaps
- :doc:`WritingAnLLVMPass`
- Information on how to write LLVM transformations and analyses.
- :doc:`WritingAnLLVMBackend`
- Information on how to write LLVM backends for machine targets.
- :doc:`CodeGenerator`
- 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.
- :doc:`TableGen <TableGen/index>`
- Describes the TableGen tool, which is used heavily by the LLVM code generator.
- :doc:`AliasAnalysis`
- Information on how to write a new alias analysis implementation or how to use existing analyses.
- :doc:`GarbageCollection`
- The interfaces source-language compilers should use for compiling GC'd programs.
- :doc:`Source Level Debugging with LLVM <SourceLevelDebugging>`
- This document describes the design and philosophy behind the LLVM source-level debugger.
- :doc:`Vectorizers`
- This document describes the current status of vectorization in LLVM.
- :doc:`ExceptionHandling`
- This document describes the design and implementation of exception handling in LLVM.
- :doc:`Bugpoint`
- Automatic bug finder and test-case reducer description and usage information.
- :doc:`BitCodeFormat`
- This describes the file format and encoding used for LLVM "bc" files.
- :doc:`System Library <SystemLibrary>`
- This document describes the LLVM System Library (
lib/System) and how to keep LLVM source code portable - :doc:`LinkTimeOptimization`
- This document describes the interface between LLVM intermodular optimizer and the linker and its design
- :doc:`GoldPlugin`
- How to build your programs with link-time optimization on Linux.
- :doc:`DebuggingJITedCode`
- How to debug JITed code with GDB.
- :doc:`MCJITDesignAndImplementation`
- Describes the inner workings of MCJIT execution engine.
- :doc:`BranchWeightMetadata`
- Provides information about Branch Prediction Information.
- :doc:`BlockFrequencyTerminology`
- Provides information about terminology used in the
BlockFrequencyInfoanalysis pass. - :doc:`SegmentedStacks`
- This document describes segmented stacks and how they are used in LLVM.
- :doc:`MarkedUpDisassembly`
- This document describes the optional rich disassembly output syntax.
- :doc:`HowToUseAttributes`
- Answers some questions about the new Attributes infrastructure.
- :doc:`NVPTXUsage`
- This document describes using the NVPTX back-end to compile GPU kernels.
- :doc:`AMDGPUUsage`
- This document describes how to use the AMDGPU back-end.
- :doc:`StackMaps`
- LLVM support for mapping instruction addresses to the location of values and allowing code to be patched.
- :doc:`BigEndianNEON`
- LLVM's support for generating NEON instructions on big endian ARM targets is somewhat nonintuitive. This document explains the implementation and rationale.
- :doc:`CoverageMappingFormat`
- This describes the format and encoding used for LLVM’s code coverage mapping.
- :doc:`Statepoints`
- This describes a set of experimental extensions for garbage collection support.
- :doc:`MergeFunctions`
- Describes functions merging optimization.
- :doc:`InAlloca`
- Description of the
inallocaargument attribute. - :doc:`FaultMaps`
- LLVM support for folding control flow into faulting machine instructions.
Information about LLVM's development process.
.. toctree:: :hidden: DeveloperPolicy MakefileGuide Projects LLVMBuild HowToReleaseLLVM Packaging ReleaseProcess Phabricator
- :doc:`DeveloperPolicy`
- The LLVM project's policy towards developers and their contributions.
- :doc:`Projects`
- 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. - :doc:`LLVMBuild`
- Describes the LLVMBuild organization and files used by LLVM to specify component descriptions.
- :doc:`MakefileGuide`
- Describes how the LLVM makefiles work and how to use them.
- :doc:`HowToReleaseLLVM`
- This is a guide to preparing LLVM releases. Most developers can ignore it.
- :doc:`ReleaseProcess`
- This is a guide to validate a new release, during the release process. Most developers can ignore it.
- :doc:`Packaging`
- Advice on packaging LLVM into a distribution.
- :doc:`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.
If you can't find what you need in these docs, try consulting the mailing lists.
- Developer's List (llvmdev)
- 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 (llvmbugs)
- This list gets emailed every time a bug is opened and closed. It is higher volume than the LLVMdev 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
- llvmbb - Bot for the main LLVM buildbot master. http://lab.llvm.org:8011/console
- bb-chapuni - An individually run buildbot master. http://bb.pgr.jp/console
- smooshlab - Apple's internal buildbot master.
- robot - Bugzilla linker. %bug <number>
- clang-bot - A geordi instance running near-trunk clang instead of gcc.