Skip to content
Switch branches/tags
Go to file
Cannot retrieve contributors at this time

Contributing to Eclipse OMR

Thanks for your interest in this project.

We welcome and encourage all kinds of contribution to the project, not only code. This includes bug reports, user experience feedback, assistance in reproducing issues and more.

If you are new to working with git, you may use our Git Crash Course to help you get started.


This project uses GitHub Issues to track ongoing development, discuss project plans, and keep track of bugs. Be sure to search for existing issues before you create another one.

Visit our Issues page on GitHub to search and submit


Our GitHub issues get labelled by committers in order to allow easier navigation, and to flag certain issues as being of interest to certain groups. A PR or Issue may have multiple labels, as many as needed to provide adequate categorization.

A subset of the labels are documented below.

  • good first issue generally refers to a task that would be suitable for someone new to the project with little experience with either the technology or even open-source projects and processes. They are intended for anyone who wants to gently get their feet wet on building, testing, or familiarizing themselves with part of the code base.

  • bug issues are functional problems, errors or unexpected behaviour.

  • build/configure labels are used to describe issues with the build and configure system (e.g., makefiles, autotools configure).

  • ci labels are used for issues and enhancements with the continuous integration system for pull request testing (e.g., Jenkins, Azure, etc.)

  • cmake labels are similar to build/configure but they apply specifically to the CMake configuration.

  • compiler arch review labels are used to indicate a review of this issue or pull request at the OMR Compiler Architecture meeting is requested prior to committing.

  • documentation labels are used for issues or enhancements to the documentation (either in the source code itself or stand-alone documentation files).

  • epic issues are used to group together related issues and to track larger goals in the project across issues.

  • GSoC Project labels are for potential ideas for Google Summer Of Code projects.

  • help wanted issues have value to the project but no immediate human resources to undertake it. Those that are looking to complete a task that someone isn't already working on can consider these.

  • license labels are used to annotate issues concerning the source code license.

  • meeting labels are used to annotate issues pertaining to project meeting agendas or minutes.

  • toolchain bug labels are used to document issues or pull requests that describe or implement a workaround to a bug in the development toolchain (such as the compiler) used to build OMR. Toolchain workarounds should be temporary in nature, and the intention of this label is to make such workarounds easy to discover in the future lest they be lost in the code.

  • tooling labels are for issues concerning support tooling needed to support any of the code or processes within the project.

Labels are also used to classify issues and pull requests by the dominant Eclipse OMR technology component they affect. For instance,

Label Component Principal Directories
comp:compiler Compiler compiler
comp:core Core OMR functionality include_code, omr
comp:diagnostic Diagnostic services ddr
comp:doc OMR documentation doc
comp:gc Garbage collector gc
comp:glue Glue code glue
comp:jitbuilder JitBuilder jitbuilder
comp:port Port library port
comp:test Unit tests and testing framework fvtest
comp:thread Thread library thread
comp:tril Tril infrastructure and tests fvtest/tril
comp:utilities OMR utilities util

Further classification by processor architecture, operating system, and bitness can be achieved with the following labels:

Submitting a contribution

You can propose contributions by sending pull requests through GitHub. Following these guidelines will help us to merge your pull requests smoothly:

  1. If you're not sure your contribution would be accepted, and want to validate your approach or idea before writing code, feel free to open an issue. However, not every feature or fix needs an issue. If the problem and fix are cleanly connected, and you have the fix in hand, feel free to just submit a pull request.

  2. Your pull request is an opportunity to explain both what changes you'd like pulled in, but also why you'd like them added. Providing clarity on why you want changes makes it easier to accept, and provides valuable context to review.

  3. Please read carefully and adhere to the legal considerations and copyright/license requirements outlined below.

  4. For each file that you modify, ensure that the current copyright year in the header at the top of the file is up-to-date with the current year. Note that renaming, moving, or copying a file does not require a copyright change.

  5. Follow the coding style and format of the code you are modifying (see the coding standards). The code base is yet to be unified in style however, so if the file you are editing seems to have a diffferent style, defer to the style of the file as you found it.

  6. Only use C++ language features supported by our compilers. A list of supported features can be found here.

  7. Follow the commit guidelines found below.

  8. We encourage you to open a pull request early, and mark it as "Work In Progress" (prefix the PR title with WIP). This allows feedback to start early, and helps create a better end product. Committers will wait until after you've removed the WIP prefix to merge your changes.

  9. If you are contributing a change to the compiler technology that involves modifications to the Testarossa IL (including, but not limited to, adding a new IL opcode, changing the properties of an opcode, or adding a new datatype) or, in the opinion of a committer, a fundamental element of compiler infrastructure, a committer will request that this pull request be presented at an upcoming OMR Compiler Architecture meeting to invite community discussion prior to merging. Issues of the same nature may also be asked to be discussed before the same architecture meeting prior to producing a pull request.

Downstream Dependencies

If a downstream project consuming OMR has a dependency on the contents of your pull request, i.e. the pull request should not be merged until all downstream preparations have been complete, you as the contributor of the pull request may use the WIP prefix in addition to comment in the said pull request to inform the committer of your particular circumstances for merging. That is, you may request a review of the pull request even though it's marked WIP, informing the committer of your desire to coordinate when the PR is merged. Once all downstream preparations have been complete it is your responsibility as the contributor to remove the WIP prefix and inform the committers that the pull request is ready for merging, pending reviews have been completed.

Commit Guidelines

The first line describes the change made. It is written in the imperative mood, and should say what happens when the patch is applied. Keep it short and simple. The first line should be less than 70 characters, where reasonable, and should be written in sentence case preferably not ending in a period. Leave a blank line between the first line and the message body.

The body should be wrapped at 72 characters, where reasonable.

Include as much information in your commit as possible. You may want to include designs and rationale, examples and code, or issues and next steps. Prefer copying resources into the body of the commit over providing external links. Structure large commit messages with headers, references etc. Remember however that the commit message is always going to be rendered in plain text.

Please add [skip ci] to the commit message when the change doesn't require a compilation, such as documentation only changes, to avoid unnecessarily wasting the project's build resources.

Use the commit footer to place commit metadata. The footer is the last block of contiguous text in the message. It is separated from the body by one or more blank lines, and as such cannot contain any blank lines. Lines in the footer are of the form:

Key: Value

When a commit has related issues or commits, explain the relation in the message body. You should also leave an Issue tag in the footer. However, if this is the final commit that fixes an issue you should leave a Closes tag (or one of the tags described here in the footer instead which will automatically close the referenced issue when this pull request is merged.

For example, if this is just one of the commits necessary to address Issue 1234 then the following is a valid commit message:

Correct race in frobnicator

This patch eliminates the race condition in issue #1234.

Issue: #1234

However, if this is the final commit that addresses the issue then the following is an acceptable commit message:

Correct race in frobnicator

This patch eliminates the race condition in issue #1234.

Closes: #1234

Commit Authorship

Be sure to author commits with the same email address that you used to sign the Eclipse Contributor Agreement.

If there are multiple authors of a commit they should all be credited with a Co-authored-by: Full Name <email address> line at the footer of each commit. Each co-author must sign the ECA.

Each time a commit is pushed, a GitHub CI check will be run automatically that verifies that the commit author(s) has signed the Eclipse Contributor Agreement. If not, the check will fail and the result will be visible in the pull request.

Example Commits

Here is an example of a good commit:

Update and expand the commit guidelines

Elaborate on the style guidelines for commit messages. These new
style guidelines reflect the conversation found in #124.

The guidelines are changed to:
- Provide guidance on how to write a good first line.
- Elaborate on formatting requirements.
- Relax the advice on using issues for nontrivial commits.
- Move issue references from the first line to the message footer.
- Encourage contributors to put more information into the commit

Issue: #124

The first line is meaningful and imperative. The body contains enough information that the reader understands the why and how of the commit, and its relation to any issues. The issue is properly tagged.

The following is an example of a bad commit:

FIX #124: Changing a couple random things in
Also, there are some bug fixes in the thread library.

The commit rolls unrelated changes together in a very bad way. There is not enough information for the commit message to be useful. The first line is not meaningful or imperative. The message is not formatted correctly and the issue is improperly referenced.

Other resources for writing good commits

Install a git commit message hook script to validate local commits

We have a script that attempts to enforce some of these commit guidelines. You can install it by following instructions similar to the ones below.

cd omr_repo_dir
cp scripts/commit-msg .git/hooks
chmod +x .git/hooks/commit-msg

If the hook declines your commit, the message will remain in omr_repo_dir/.git/COMMIT_EDITMSG.

Be sure to update your version of the script occasionally as it may evolve as our commit guidelines evolve.

Legal considerations

Please read the Eclipse Foundation policy on accepting contributions via Git.

Your contribution cannot be accepted unless you have a signed ECA - Eclipse Foundation Contributor Agreement in place. If you have an active signed Eclipse CLA (the CLA was updated by the Eclipse Foundation to become the ECA in August 2016), then that signed CLA is sufficient. You will have to sign the ECA once your CLA expires.

Here is the checklist for contributions to be acceptable:

  1. Create an account at Eclipse.
  2. Add your GitHub user name in your account settings.
  3. Log into the project's portal and sign the "Eclipse ECA".
  4. Ensure that you author the commit using the same email address as your Eclipse account.
  5. Include the appropriate copyright notice and license at the top of each file.

Your signing of the ECA will be verified by a webservice called 'ip-validation' that checks the email address(es) that authored your commits has signed the ECA. Note: This service is case-sensitive, so ensure the email that signed the ECA and that authored your commits is the same, down to the case.

Copyright Notice and Licensing Requirements

It is the responsibility of each contributor to obtain legal advice, and to ensure that their contributions fulfill the legal requirements of their organization. This document is not legal advice.

OMR is dual-licensed under the Eclipse Public License 2.0 and the Apache License v2.0. Any previously unlicensed contribution should be released under the same license.

  • If you wish to contribute code under a different license, you must consult with a committer before contributing.
  • For any scenario not covered by this document, please discuss the copyright notice and licensing requirements with a committer before contributing.

The template for the copyright notice and dual-license is as follows:

 *  Copyright (c) 2017, 2017 ${author} and others
 *  This program and the accompanying materials are made available under
 *  the terms of the Eclipse Public License 2.0 which accompanies this
 *  distribution and is available at
 *  or the Apache License, Version 2.0 which accompanies this distribution and
 *  is available at
 *  This Source Code may also be made available under the following
 *  Secondary Licenses when the conditions for such availability set
 *  forth in the Eclipse Public License, v. 2.0 are satisfied: GNU
 *  General Public License, version 2 with the GNU Classpath
 *  Exception [1] and GNU General Public License, version 2 with the
 *  OpenJDK Assembly Exception [2].
 *  [1]
 *  [2]
 *  SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0 WITH Classpath-exception-2.0 OR LicenseRef-GPL-2.0 WITH Assembly-exception