How To Release LLVM To The Public

1. Introduction
2. Qualification Criteria
3. Release Timeline
4. Release Process

Written by Tanya Lattner, Reid Spencer, John Criswell

Introduction

This document collects information about successfully releasing LLVM (including subprojects llvm-gcc and Clang) to the public. It is the release manager's responsibility to ensure that a high quality build of LLVM is released.

Release Timeline

LLVM is released on a time based schedule (currently every 6 months). We do not have dot releases because of the nature of LLVM incremental development philosophy. The release schedule is roughly as follows:

1. Set code freeze and branch creation date for 6 months after last code freeze date. Announce release schedule to the LLVM community and update the website.
2. Create release branch and begin release process.
3. Send out pre-release for first round of testing. Testing will last 7-10 days. During the first round of testing, regressions should be found and fixed. Patches are merged from mainline to the release branch.
4. Generate and send out second pre-release. Bugs found during this time will not be fixed unless absolutely critical. Bugs introduce by patches merged in will be fixed and if so, a 3rd round of testing is needed.
5. The release notes should be updated during the first and second round of pre-release testing.
6. Finally, release!

Release Process

1. Release Administrative Tasks

1. Create Release Branch
2. Update Version Numbers

2. Building the Release

1. Build the LLVM Source Distributions
2. Build LLVM
3. Build the LLVM-GCC Binary Distribution
4. Build the Clang Binary Distribution
5. Target Specific Build Details

3. Release Qualification Criteria

1. Qualify LLVM
2. Qualify LLVM-GCC
3. Qualify Clang
4. Specific Target Qualification Details

4. Community Testing
5. Release Patch Rules
6. Release final tasks

1. Update Documentation
2. Tag the LLVM Release Branch
3. Update the LLVM Demo Page
4. Update the LLVM Website
5. Announce the Release

Release Administrative Tasks
This section describes a few administrative tasks that need to be done for the release process to begin. Specifically, it involves creating the release branch, resetting version numbers, and creating the release tarballs for the release team to begin testing.
Create Release Branch

Branch the Subversion HEAD using the following procedure:

1. Verify that the current Subversion HEAD is in decent shape by examining nightly tester or buildbot results.

2. Request all developers to refrain from committing. Offenders get commit rights taken away (temporarily).

3. Create the release branch for `llvm`, `llvm-gcc4.2`, `clang`, and the `test-suite`. The branch name will be `release_XX`,where `XX` is the major and minor release numbers. `Clang` will have a different release number than `llvm`/ `llvm-gcc4` since its first release was years later (still deciding if this will be true or not). These branches can be created without checking out anything from subversion.

       svn copy https://llvm.org/svn/llvm-project/llvm/trunk \
                https://llvm.org/svn/llvm-project/llvm/branches/release_XX
       svn copy https://llvm.org/svn/llvm-project/llvm-gcc-4.2/trunk \
                https://llvm.org/svn/llvm-project/llvm-gcc-4.2/branches/release_XX
       svn copy https://llvm.org/svn/llvm-project/test-suite/trunk \
                https://llvm.org/svn/llvm-project/test-suite/branches/release_XX
       svn copy https://llvm.org/svn/llvm-project/cfe/trunk \
                https://llvm.org/svn/llvm-project/cfe/branches/release_XX

4. Advise developers they can work on Subversion HEAD again.

5. The Release Manager should switch to the release branch (as all changes to the release will now be done in the branch). The easiest way to do this is to grab another working copy using the following commands:

       svn co https://llvm.org/svn/llvm-project/llvm/branches/release_XX
       svn co https://llvm.org/svn/llvm-project/llvm-gcc-4.2/branches/release_XX
       svn co https://llvm.org/svn/llvm-project/test-suite/branches/release_XX
       svn co https://llvm.org/svn/llvm-project/cfe/branches/release_XX

Update LLVM Version

After creating the LLVM release branch, update the release branches' autoconf/configure.ac version from X.Xsvn to just X.X. Update it on mainline as well to be the next version (X.X+1svn). Regenerated the configure script for both. This must be done for both `llvm` and the `test-suite`.

FIXME: Add a note about `clang`.

In addition, the version number of all the Bugzilla components must be updated for the next release.

Build the LLVM Source Distributions

Create source distributions for `LLVM`, `LLVM-GCC`, `clang`, and the llvm `test-suite` by exporting the source from Subversion and archiving it. This can be done with the following commands:

    svn export https://llvm.org/svn/llvm-project/llvm/branches/release_XX llvm-X.X
    svn export https://llvm.org/svn/llvm-project/llvm-gcc-4.2/branches/release_XX llvm-gcc4.2-X.X.source
    svn export https://llvm.org/svn/llvm-project/test-suite/branches/release_XX llvm-test-X.X
    svn export https://llvm.org/svn/llvm-project/cfe/branches/release_XX clang-X.X
    tar -czvf - llvm-X.X          | gzip > llvm-X.X.tar.gz
    tar -czvf - llvm-test-X.X     | gzip > llvm-test-X.X.tar.gz
    tar -czvf - llvm-gcc4.2-X.X.source | gzip > llvm-gcc-4.2-X.X.source.tar.gz
    tar -czvf - clang-X.X | gzip > clang-X.X.tar.gz

Building the Release
The build of `llvm`, `llvm-gcc`, and `clang` must be free of errors and warnings in both debug, release, and release-asserts builds. If all builds are clean, then the release passes build qualification.

1. debug: ENABLE_OPTIMIZED=0
2. release: ENABLE_OPTIMIZED=1
3. release-asserts: ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1

Build LLVM

Build both debug, release (optimized), and release-asserts versions of LLVM on all supported platforms. Direction to build llvm are here.

Build the LLVM GCC Binary Distribution

Creating the LLVM GCC binary distribution (release/optimized) requires performing the following steps for each supported platform:

1. Build the LLVM GCC front-end by following the directions in the README.LLVM file. The frontend must be compiled with c, c++, objc (mac only), objc++ (mac only) and fortran support.
2. Please boostrap as well.
3. Be sure to build with LLVM_VERSION_INFO=X.X, where X is the major and minor release numbers.
4. Copy the installation directory to a directory named for the specific target. For example on Red Hat Enterprise Linux, the directory would be named `llvm-gcc4.2-2.6-x86-linux-RHEL4`. Archive and compress the new directory.

Build Clang Binary Distribution

Creating the Clang binary distribution (debug/release/release-asserts) requires performing the following steps for each supported platform:

1. Build clang according to the directions here.
2. Build both a debug and release version of clang, but the binary will be a release build.
3. Package clang (details to follow).

Target Specific Build Details

The table below specifies which compilers are used for each arch/os combination when qualifying the build of `llvm`, `llvm-gcc`, `clang.`

Architecture | OS | compiler
--- | --- | ---
x86-32 | Mac OS 10.5 | gcc 4.0.1
x86-32 | Linux | gcc 4.2.X, gcc 4.3.X
x86-32 | FreeBSD | gcc 4.2.X
x86-32 | mingw | gcc 3.4.5
x86-64 | Mac OS 10.5 | gcc 4.0.1
x86-64 | Linux | gcc 4.2.X, gcc 4.3.X
x86-64 | FreeBSD | gcc 4.2.X

Building the Release
A release is qualified when it has no regressions from the previous release (or baseline). Regressions are related to correctness only and not performance at this time. Regressions are new failures in the set of tests that are used to qualify each product and only include things on the list. Ultimately, there is no end to the number of possible bugs in a release. We need a very concrete and definitive release criteria that ensures we have monotonically improving quality on some metric. The metric we use is described below. This doesn't mean that we don't care about other things, but this are things that must be satisfied before a release can go out
Qualify LLVM

LLVM is qualified when it has a clean dejagnu test run without a frontend and it has no regressions when using either `llvm-gcc` or `clang` with the `test-suite` from the previous release.

Qualify LLVM-GCC

`LLVM-GCC` is qualified when front-end specific tests in the `llvm` dejagnu test suite all pass and there are no regressions in the `test-suite`.

We do not use the gcc dejagnu test suite as release criteria.

Qualify Clang
`Clang` is qualified when front-end specific tests in the `llvm` dejagnu test suite all pass, clang's own test suite passes cleanly, and there are no regressions in the `test-suite`.
Specific Target Qualification Details

Architecture | OS | llvm-gcc baseline | clang baseline | tests
--- | --- | --- | --- | ---
x86-32 | Mac OS 10.5 | last release | none | llvm dejagnu, clang tests, test-suite (including spec)
x86-32 | Linux | last release | none | llvm dejagnu, clang tests, test-suite (including spec)
x86-32 | FreeBSD | none | none | llvm dejagnu, clang tests, test-suite
x86-32 | mingw | last release | none | QT
x86-64 | Mac OS 10.5 | last release | none | llvm dejagnu, clang tests, test-suite (including spec)
x86-64 | Linux | last release | none | llvm dejagnu, clang tests, test-suite (including spec)
x86-64 | FreeBSD | none | none | llvm dejagnu, clang tests, test-suite

Community Testing

Once all testing has been completed and appropriate bugs filed, the pre-release tar balls may be put on the website and the LLVM community is notified. Ask that all LLVM developers test the release in 2 ways:

1. Download llvm-X.X, llvm-test-X.X, and the appropriate llvm-gcc4 and/or clang binary. Build LLVM. Run "make check" and the full llvm-test suite (make TEST=nightly report).
2. Download llvm-X.X, llvm-test-X.X, and the llvm-gcc4 and/or clang source. Compile everything. Run "make check" and the full llvm-test suite (make TEST=nightly report).

Ask LLVM developers to submit the report and make check results to the list. Attempt to verify that there are no regressions from the previous release. The results are not used to qualify a release, but to spot other potential problems. For unsupported targets, verify that make check at least is clean.

During the first round of testing time, all regressions must be fixed before the second pre-release is created.

If this is the second round of testing, this is only to ensure the 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 step.

Release Patch Rules

Below are the rules regarding patching the release branch.

- Patches applied to the release branch are only applied by the release manager.
- During the first round of testing, patches that fix regressions or that are small and relatively risk free (verified by the appropriate code owner) are applied to the branch. Code owners are asked to be very conservative in approving patches for the branch and we reserve the right to reject any patch that does not fix a regression as previously defined.
- During the remaining rounds of testing, only patches that fix regressions may be applied.
Release Final Tasks

The final stages of the release process involving taging the release branch, updating documentation that refers to the release, and updating the demo page.

FIXME: Add a note if anything needs to be done to the clang website. Eventually the websites will be merged hopefully.

Update Documentation

Review the documentation and ensure that it is up to date. The Release Notes must be updated to reflect 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 avaiable from Subversion and changes in basic system requirements. Merge both changes from mainline into the release branch.

Tag the Release Branch

Tag the release branch using the following procedure:

    svn copy https://llvm.org/svn/llvm-project/llvm/branches/release_XX \
             https://llvm.org/svn/llvm-project/llvm/tags/RELEASE_XX
    svn copy https://llvm.org/svn/llvm-project/llvm-gcc-4.2/branches/release_XX \
             https://llvm.org/svn/llvm-project/llvm-gcc-4.2/tags/RELEASE_XX
    svn copy https://llvm.org/svn/llvm-project/test-suite/branches/release_XX \
             https://llvm.org/svn/llvm-project/test-suite/tags/RELEASE_XX

Update the LLVM Demo Page

The LLVM demo page must be updated to use the new release. This consists of using the llvm-gcc binary and building LLVM. Update the website demo page configuration to use the new release.

Update the LLVM Website

The website must be updated before the release announcement is sent out. Here is what to do:

1. Check out the `website` module from CVS.
2. Create a new subdirectory X.X in the releases directory.
3. Commit the `llvm`, `test-suite`, `llvm-gcc` source, `clang source`, `clang binaries`, and `llvm-gcc` binaries in this new directory.
4. Copy and commit the `llvm/docs` and `LICENSE.txt` files into this new directory. The docs should be built with BUILD_FOR_WEBSITE=1.
5. Commit the index.html to the release/X.X directory to redirect (use from previous release.
6. Update the `releases/download.html` file with the new release.
7. Update the `releases/index.html` with the new release and link to release documentation.
8. Finally, update the main page (`index.html` and sidebar) to point to the new release and release announcement. Make sure this all gets committed back into Subversion.

Announce the Release

Have Chris send out the release announcement when everything is finished.