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How To Release LLVM To The Public
This document contains information about successfully releasing LLVM ---
including sub-projects: e.g., ``clang`` and ``compiler-rt`` --- to the public.
It is the Release Manager's responsibility to ensure that a high quality build
of LLVM is released.
If you're looking for the document on how to test the release candidates and
create the binary packages, please refer to the :doc:`ReleaseProcess` instead.
.. _timeline:
Release Timeline
LLVM is released on a time based schedule --- with major releases roughly
every 6 months. In between major releases there may be dot releases.
The release manager will determine if and when to make a dot release based
on feedback from the community. Typically, dot releases should be made if
there are large number of bug-fixes in the stable branch or a critical bug
has been discovered that affects a large number of users.
Unless otherwise stated, dot releases will follow the same procedure as
major releases.
Annual Release Schedule
Here is the annual release schedule for LLVM. This is meant to be a
guide, and release managers are not required to follow this exactly.
Releases should be tagged on Tuesdays.
=============================== =========================
Release Approx. Date
=============================== =========================
*release branch: even releases* *4th Tue in January*
*release branch: odd releases* *4th Tue in July*
X.0.0-rc1 3 days after branch.
X.0.0-rc2 2 weeks after branch.
X.0.0-rc3 4 weeks after branch
**X.0.0-final** **6 weeks after branch**
**X.0.1** **8 weeks after branch**
**X.0.2** **10 weeks after branch**
**X.0.3** **12 weeks after branch**
**X.0.4** **14 weeks after branch**
**X.0.5** **16 weeks after branch**
**X.0.6 (if necessary)** **18 weeks after branch**
=============================== =========================
Release Process Summary
* Announce release schedule to the LLVM community and update the website. Do
this at least 3 weeks before the -rc1 release.
* Create release branch and begin release process.
* Send out release candidate sources for first round of testing. Testing lasts
6 weeks. During the first round of testing, any regressions found should be
fixed. Patches are merged from mainline into the release branch. Also, all
features need to be completed during this time. Any features not completed at
the end of the first round of testing will be removed or disabled for the
* Generate and send out the second release candidate sources. Only *critical*
bugs found during this testing phase will be fixed. Any bugs introduced by
merged patches will be fixed. If so a third round of testing is needed.
* The release notes are updated.
* Finally, release!
* Announce bug fix release schedule to the LLVM community and update the website.
* Do bug-fix releases every two weeks until X.0.5 or X.0.6 (if necessary).
Release Process
.. contents::
Release Administrative Tasks
This section describes a few administrative tasks that need to be done for the
release process to begin. Specifically, it involves:
* Updating version numbers,
* Creating the release branch, and
* Tagging release candidates for the release team to begin testing.
Create Release Branch
Branch the Git trunk using the following procedure:
#. Remind developers that the release branching is imminent and to refrain from
committing patches that might break the build. E.g., new features, large
patches for works in progress, an overhaul of the type system, an exciting
new TableGen feature, etc.
#. Verify that the current git trunk is in decent shape by
examining nightly tester and buildbot results.
#. Bump the version in trunk to N.0.0git and tag the commit with llvmorg-N-init.
If ``X`` is the version to be released, then ``N`` is ``X + 1``.
$ git tag -a llvmorg-N-init
#. Clear the release notes in trunk.
#. Create the release branch from the last known good revision from before the
version bump. The branch's name is release/X.x where ``X`` is the major version
number and ``x`` is just the letter ``x``.
#. All tags and branches need to be created in both the llvm/llvm-project and
llvm/llvm-test-suite repos.
Update LLVM Version
After creating the LLVM release branch, update the release branches'
``CMakeLists.txt`` versions from '``X.0.0git``' to '``X.0.0``'.
In addition, the version numbers of all the Bugzilla components must be updated
for the next release.
Tagging the LLVM Release Candidates
Tag release candidates:
$ git tag -a llvmorg-X.Y.Z-rcN
The Release Manager must supply pre-packaged source tarballs for users. This can
be done with the script in utils/release.
Tarballs, release binaries, or any other release artifacts must be uploaded to
GitHub. This can be done using the script in utils/release.
$ upload --token <github-token> --release X.Y.Z-rcN --files <release_files>
$ ./ -release X.Y.Z -rc $RC
This will generate source tarballs for each LLVM project being validated, which
can be uploaded to github for further testing.
Build The Binary Distribution
Creating the binary distribution requires following the instructions
:doc:`here <ReleaseProcess>`.
That process will perform both Release+Asserts and Release builds but only
pack the Release build for upload. You should use the Release+Asserts sysroot,
normally under ``final/Phase3/Release+Asserts/llvmCore-3.8.1-RCn.install/``,
for test-suite and run-time benchmarks, to make sure nothing serious has
passed through the net. For compile-time benchmarks, use the Release version.
The minimum required version of the tools you'll need are :doc:`here <GettingStarted>`
Release Qualification Criteria
There are no official release qualification criteria. It is up to the
the release manager to determine when a release is ready. The release manager
should pay attention to the results of community testing, the number of outstanding
bugs, and then number of regressions when determining whether or not to make a
The community values time based releases, so releases should not be delayed for
too long unless there are critical issues remaining. In most cases, the only
kind of bugs that are critical enough to block a release would be a major regression
from a previous release.
Official Testing
A few developers in the community have dedicated time to validate the release
candidates and volunteered to be the official release testers for each
These will be the ones testing, generating and uploading the official binaries
to the server, and will be the minimum tests *necessary* for the release to
This will obviously not cover all OSs and distributions, so additional community
validation is important. However, if community input is not reached before the
release is out, all bugs reported will have to go on the next stable release.
The official release managers are:
* Major releases (X.0): Hans Wennborg
* Stable releases (X.n): Tom Stellard
The official release testers are volunteered from the community and have
consistently validated and released binaries for their targets/OSs. To contact
them, you should post on the `Discourse forums (Project
Infrastructure - Release Testers). <>`_
The official testers list is in the file ``RELEASE_TESTERS.TXT``, in the ``LLVM``
Community Testing
Once all testing has been completed and appropriate bugs filed, the release
candidate tarballs are put on the website and the LLVM community is notified.
We ask that all LLVM developers test the release in any the following ways:
#. Download ``llvm-X.Y``, ``llvm-test-X.Y``, and the appropriate ``clang``
binary. Build LLVM. Run ``make check`` and the full LLVM test suite (``make
TEST=nightly report``).
#. Download ``llvm-X.Y``, ``llvm-test-X.Y``, and the ``clang`` sources. Compile
everything. Run ``make check`` and the full LLVM test suite (``make
TEST=nightly report``).
#. Download ``llvm-X.Y``, ``llvm-test-X.Y``, and the appropriate ``clang``
binary. Build whole programs with it (ex. Chromium, Firefox, Apache) for
your platform.
#. Download ``llvm-X.Y``, ``llvm-test-X.Y``, and the appropriate ``clang``
binary. Build *your* programs with it and check for conformance and
performance regressions.
#. Run the :doc:`release process <ReleaseProcess>`, if your platform is
*different* than that which is officially supported, and report back errors
only if they were not reported by the official release tester for that
We also ask that the OS distribution release managers test their packages with
the first candidate of every release, and report any *new* errors in Bugzilla.
If the bug can be reproduced with an unpatched upstream version of the release
candidate (as opposed to the distribution's own build), the priority should be
release blocker.
During the first round of testing, all regressions must be fixed before the
second release candidate is tagged.
In the subsequent stages, the testing is only to ensure that bug
fixes previously merged in have not created new major problems. *This is not
the time to solve additional and unrelated bugs!* If no patches are merged in,
the release is determined to be ready and the release manager may move onto the
next stage.
Reporting Regressions
Every regression that is found during the tests (as per the criteria above),
should be filled in a bug in Bugzilla with the priority *release blocker* and
blocking a specific release.
To help manage all the bugs reported and which ones are blockers or not, a new
"[meta]" bug should be created and all regressions *blocking* that Meta. Once
all blockers are done, the Meta can be closed.
If a bug can't be reproduced, or stops being a blocker, it should be removed
from the Meta and its priority decreased to *normal*. Debugging can continue,
but on trunk.
Backport Requests
Instructions for requesting a backport to a stable branch can be found :doc:`here <GitHub>`.
Triaging Bug Reports for Releases
This section describes how to triage bug reports:
#. Search for bugs with a Release Milestone that have not been added to the
"Release Status" github project:
Replace 14.0.5 in this query with the version from the Release Milestone being
Add these bugs to the "Release Status" project.
#. Navigate to the `Release Status project <>`_
to see the list of bugs that are being considered for the release.
#. Review each bug and first check if it has been fixed in main. If it has, update
its status to "Needs Pull Request", and create a pull request for the fix
using the /cherry-pick or /branch comments if this has not been done already.
#. If a bug has been fixed and has a pull request created for backporting it,
then update its status to "Needs Review" and notify a knowledgeable reviewer.
Usually you will want to notify the person who approved the patch in Phabricator,
but you may use your best judgement on who a good reviewer would be. Once
you have identified the reviewer(s), assign the issue to them and mention
them (i.e @username) in a comment and ask them if the patch is safe to backport.
You should also review the bug yourself to ensure that it meets the requirements
for committing to the release branch.
#. Once a bug has been reviewed, add the release:reviewed label and update the
issue's status to "Needs Merge". Check the pull request associated with the
issue. If all the tests pass, then the pull request can be merged. If not,
then add a comment on the issue asking someone to take a look at the failures.
#. Once the pull request has been merged push it to the official release branch:
git checkout release/XX.x
git pull --ff-only release/XX.x
git push release/XX.x:release/XX.x
Then add a comment to the issue stating that the fix has been merged along with
the git hashes from the release branch. Add the release:merged label to the issue
and close it.
Release Patch Rules
Below are the rules regarding patching the release branch:
#. Patches applied to the release branch may only be applied by the release
manager, the official release testers or the code owners with approval from
the release manager.
#. Release managers are encouraged, but not required, to get approval from code
owners before approving patches. If there is no code owner or the code owner
is unreachable then release managers can ask approval from patch reviewers or
other developers active in that area.
#. *Before RC1* Patches should be limited to bug fixes, important optimization
improvements, or completion of features that were started before the branch
was created. As with all phases, release managers and code owners can reject
patches that are deemed too invasive.
#. *Before RC2* Patches should be limited to bug fixes or backend specific
improvements that are determined to be very safe.
#. *Before RC3/Final Major Release* Patches should be limited to critical
bugs or regressions.
#. *Bug fix releases* Patches should be limited to bug fixes or very safe
and critical performance improvements. Patches must maintain both API and
ABI compatibility with the previous major release.
Merging Patches
Use the ``git cherry-pick -x`` command to merge patches to the release branch:
#. ``git cherry-pick -x abcdef0``
#. Run regression tests.
Release Final Tasks
The final stages of the release process involves tagging the "final" release
branch, updating documentation that refers to the release, and updating the
demo page.
Update Documentation
Review the documentation in the release branch and ensure that it is up
to date. The "Release Notes" must be updated to reflect new features, bug
fixes, new known issues, and changes in the list of supported platforms.
The "Getting Started Guide" should be updated to reflect the new release
version number tag available from Subversion and changes in basic system
.. _tag:
Tag the LLVM Final Release
Tag the final release sources:
$ git tag -a llvmorg-X.Y.Z
$ git push llvmorg-X.Y.Z
Update the LLVM Website
The website must be updated before the release announcement is sent out. Here
is what to do:
#. Check out the ``www-releases`` module from GitHub.
#. Create a new sub-directory ``X.Y.Z`` in the releases directory.
#. Copy and commit the ``llvm/docs`` and ``LICENSE.txt`` files into this new
#. Update the ``releases/download.html`` file with links to the release
binaries on GitHub.
#. Update the ``releases/index.html`` with the new release and link to release
#. After you push the changes to the www-releases repo, someone with admin
access must login to and manually pull the new
changes into /data/www-releases/. This is where the website is served from.
#. Finally checkout the llvm-www repo and update the main page
(``index.html`` and sidebar) to point to the new release and release
Announce the Release
Create a new post in the `Announce Category <>`_
once all the release tasks are complete. For X.0.0 releases, make sure to include a
link to the release notes in the post. For X.0.1+ releases, generate a changelog
using this command and add it to the post.
$ git log --format="[%h %s](" llvmorg-X.0.N-1..llvmorg-X.0.N
Once the release has been announced add a link to the announcement on the llvm
homepage (from the llvm-www repo) in the "Release Emails" section.