Getting Involved

LLVM welcomes contributions of all kinds. To get started, please review the following topics:

Contributing to LLVM
An overview on how to contribute to LLVM.
LLVM Developer Policy
The LLVM project’s policy towards developers and their contributions.
LLVM Code-Review Policy and Practices
The LLVM project’s code-review process.
LLVM Community Support Policy
The LLVM support policy for core and non-core components.
Sphinx Quickstart Template
A template + tutorial for writing new Sphinx documentation. It is meant to be read in source form.
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.
How to submit an LLVM bug report
Instructions for properly submitting information about any bugs you run into in the LLVM system.
LLVM Bug Life Cycle
Describes how bugs are reported, triaged and closed.
LLVM Coding Standards
Details the LLVM coding standards and provides useful information on writing efficient C++ code.
LLVM GitHub User Guide
Describes how to use the llvm-project repository on GitHub.
Bisecting LLVM code
Describes how to use git bisect on LLVM’s repository.
Policies on git repositories
Collection of policies around the git repositories.

Development Process

Information about LLVM’s development process.

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.
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.
How To Add Your Build Configuration To LLVM Buildbot Infrastructure
Instructions for adding new builder to LLVM buildbot master.
Advice on Packaging LLVM
Advice on packaging LLVM into a distribution.
Release notes for the current release
This describes new features, known bugs, and other limitations.

Forums & Mailing Lists

If you can’t find what you need in these docs, try consulting the Discourse forums. There are also commit mailing lists for all commits to the LLVM Project. The LLVM Community Code of Conduct applies to all these forums and mailing lists.

LLVM Discourse
The forums for all things LLVM and related sub-projects. There are categories and subcategories for a wide variety of areas within LLVM. You can also view tags or search for a specific topic.
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.
LLVM Announcements
If you just want project wide announcements such as releases, developers meetings, or blog posts, then you should check out the Announcement category on LLVM Discourse.

Online Sync-Ups

A number of regular calls are organized on specific topics. It should be expected that the range of topics will change over time. At the time of writing, the following sync-ups are organized. The LLVM Community Code of Conduct applies to all online sync-ups.

If you’d like to organize a new sync-up, please add the info in the table below. Please also create a calendar event for it and invite calendar@llvm.org to the event, so that it’ll show up on the LLVM community calendar. Please see Guidance on what to put into LLVM community calendar invites for more guidance on what to add to your calendar invite.

LLVM regular sync-up calls
Topic Frequency Calendar link Minutes/docs link
Loop Optimization Working Group Every 2 weeks on Wednesday ics Minutes/docs
RISC-V Every 2 weeks on Thursday ics gcal  
Scalable Vectors and Arm SVE Monthly, every 3rd Tuesday ics gcal Minutes/docs
ML Guided Compiler Optimizations Monthly   Minutes/docs
LLVM security group Monthly, every 3rd Tuesday ics gcal Minutes/docs
CIRCT Weekly, on Wednesday   Minutes/docs
MLIR design meetings Weekly, on Thursdays   Minutes/docs
flang Multiple meeting series, documented here    
OpenMP Multiple meeting series, documented here    
LLVM Alias Analysis Every 4 weeks on Tuesdays ics Minutes/docs
Vector Predication Every 2 weeks on Tuesdays, 3pm UTC   Minutes/docs
LLVM Pointer Authentication Every month on Mondays ics Minutes/docs
MemorySSA in LLVM Every 8 weeks on Mondays ics gcal Minutes/docs
LLVM Embedded Toolchains Every 4 weeks on Thursdays ics gcal Minutes/docs
Clang C and C++ Language Working Group 1st and 3rd Wednesday of the month gcal Minutes/docs
LLVM SPIR-V Backend Working Group Every week on Thursday   Meeting details/agenda
SYCL Upstream Working Group Every 2 weeks on Mondays gcal Meeting details/agenda

Office hours

A number of experienced LLVM contributors make themselves available for a chat on a regular schedule, to anyone who is looking for some guidance. Please find the list of who is available when, through which medium, and what their area of expertise is. Don’t be too shy to dial in!

The LLVM Community Code of Conduct applies to all office hours.

Of course, people take time off from time to time, so if you dial in and you don’t find anyone present, chances are they happen to be off that day.

LLVM office hours
Name In-scope topics When? Where? Languages
Kristof Beyls General questions on how to contribute to LLVM; organizing meetups; submitting talks; and other general LLVM-related topics. Arm/AArch64 codegen. LLVM security group. LLVM Office Hours. Every 2nd and 4th Wednesday of the month at 9.30am CET, for 30 minutes. ics Jitsi English, Flemish, Dutch
Alina Sbirlea General questions on how to contribute to LLVM; women in compilers; MemorySSA, BatchAA, various loop passes, new pass manager. Monthly, 2nd Tuesdays, 10.00am PT/7:00pm CET, for 30 minutes. ics gcal GoogleMeet English, Romanian
Aaron Ballman (he/him) Clang internals; frontend attributes; clang-tidy; clang-query; AST matchers Monthly, 2nd Monday of the month at 10:00am Eastern and again at 2:00pm Eastern, for 30 minutes (will run longer as needed). ics gcal GoogleMeet English, Norwegian (not fluently)
Johannes Doerfert (he/him) OpenMP, LLVM-IR, interprocedural optimizations, Attributor, workshops, research, … Every week, Wednesdays 9:30am (Pacific Time), for 1 hour. ics MS Teams English, German
Tobias Grosser General questions on how to contribute to LLVM/MLIR, Polly, Loop Optimization, FPL, Research in LLVM, PhD in CS, Summer of Code. Monthly, last Monday of the month at 18:00 London time (typically 9am PT), for 30 minutes. Video Call English, German, Spanish, French
Anastasia Stulova Clang internals for C/C++ language extensions and dialects, OpenCL, GPU, SPIR-V, how to contribute, women in compilers. Monthly, 2nd Thursday of the month at 17:00 BST - London time (9:00am PT except for 2 weeks in spring), 1 hour slot. GoogleMeet English, Russian, German (not fluently)
Alexey Bader SYCL compiler, offload tools, OpenCL and SPIR-V, how to contribute. Monthly, 2nd Monday of the month at 9:30am PT, for 30 minutes. GoogleMeet English, Russian
Maksim Panchenko BOLT internals, IR, new passes, proposals, etc. Monthly, 2nd Wednesday of the month at 11:00am PT, for 30 minutes. Zoom English, Russian
Michal Paszkowski SPIR-V backend, IGC, OpenCL, and IR transformations Monthly, 3rd Thursday of the month at 21:00 Warsaw/Poland time, 1 hour slot. MS Teams English, Polish
Quentin Colombet (he/him) LLVM/MLIR; Codegen (Instruction selection (GlobalISel/SDISel), Machine IR, Register allocation, etc.); Optimizations; MCA Monthly, 1st Wednesday of the month at 8.00am PT, for 30 minutes. ics gcal Google meet English, French
Paulo Matos (he/him) WebAssembly backend; LLVM IR; Monthly, 1st Monday of the month at 11:00am Europe/Berlin, for 30 minutes. Igalia Jitsi English, Portuguese, German

Guidance for office hours hosts

  • If you’re interested in becoming an office hours host, please add your information to the list above. Please create a calendar event for it and invite calendar@llvm.org to the event so that it’ll show up on the LLVM community calendar. Please see Guidance on what to put into LLVM community calendar invites for more guidance on what to add to your calendar invite.

  • When starting an office hours session, consider typing something like “Hi, I’m available for chats in the next half hour at video chat URL. I’m looking forward to having conversations on the video chat or here.” on the LLVM chat channels that you are already on. These could include:

    Doing this can help:
    • overcome potential anxiety to call in for a first time,
    • people who prefer to first exchange a few messages through text chat before dialing in, and
    • remind the wider community that office hours do exist.
  • If you decide to no longer host office hours, please do remove your entry from the list above.

IRC

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

The #llvm-build channel has a bot for LLVM buildbot status changes. The bot will post a message with a link to a build bot and a blamelist when a build goes from passing to failing and again (without the blamelist) when the build goes from failing back to passing. It is a good channel for actively monitoring build statuses, but it is a noisy channel due to the automated messages. The channel is not actively moderated.

In addition to the traditional IRC there is a Discord chat server available. To sign up, please use this invitation link.

Meetups and social events

Besides developer meetings and conferences, there are several user groups called LLVM Socials. We greatly encourage you to join one in your city. Or start a new one if there is none:

How to start LLVM Social in your town

Community wide proposals

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

Moving LLVM Projects to GitHub
Proposal to move from SVN/Git to GitHub.
Bugpoint Redesign
Design doc for a redesign of the Bugpoint tool.
Test-Suite Extensions
Proposals for additional benchmarks/programs for llvm’s test-suite.
Variable Names Plan
Proposal to change the variable names coding standard.
Vectorization Plan
Proposal to model the process and upgrade the infrastructure of LLVM’s Loop Vectorizer.
Vector Predication Roadmap
Proposal for predicated vector instructions in LLVM.

LLVM community calendar

We aim to maintain a public calendar view of all events happening in the LLVM community such as Online Sync-Ups and Office hours. The calendar can be found at https://calendar.google.com/calendar/u/0/embed?src=calendar@llvm.org and can also be seen inline below:

Guidance on what to put into LLVM community calendar invites

To add your event, create a calendar event for it and invite calendar@llvm.org on it. Your event should then show up on the community calendar.

Please put the following pieces of information in your calendar invite:

  • Write a single paragraph describing what the event is about. Include things such as who the event is for and what sort of topics are discussed.
  • State explicitly that the LLVM Community Code of Conduct applies to this event.
  • Make it clear who:
    • the organizer is.
    • the person to contact is in case of any code-of-conduct issues. Typically, this would be the organizer.
  • If you have meeting minutes for your event, add a pointer to where those live. A good place for meeting minutes could be as a post on LLVM Discourse.

An example invite looks as follows

This event is a meetup for all developers of LLDB. Meeting agendas are posted
on discourse before the event.

Attendees are required to adhere to the LLVM Code of Conduct
(https://llvm.org/docs/CodeOfConduct.html). For any Code of Conduct reports,
please contact the organizers, and also email conduct@llvm.org.

Agenda/Meeting Minutes: Link to minutes

Organizer(s): First Surname (name@email.com)