This document contains information about successfully releasing LLVM — including subprojects: e.g., clang and dragonegg — to the public. It is the Release Manager's responsibility to ensure that a high quality build of LLVM is released.
LLVM is released on a time based schedule — roughly every 6 months. We do not normally have dot releases because of the nature of LLVM's incremental development philosophy. That said, the only thing preventing dot releases for critical bug fixes from happening is a lack of resources — testers, machines, time, etc. And, because of the high quality we desire for LLVM releases, we cannot allow for a truncated form of release qualification.
The release process is roughly as follows:
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.
Create release branch and begin release process.
Send out release candidate sources for first round of testing. Testing lasts 7-10 days. 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 release.
Generate and send out the second release candidate sources. Only critial 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!
This section describes a few administrative tasks that need to be done for the release process to begin. Specifically, it involves:
Branch the Subversion 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 Subversion trunk is in decent shape by examining nightly tester and buildbot results.
Create the release branch for llvm, clang, the test-suite, and dragonegg from the last known good revision. The branch's name is release_XY, where X is the major and Y the minor release numbers. The branches should be created using the following commands:
$ svn copy https://llvm.org/svn/llvm-project/llvm/trunk \
https://llvm.org/svn/llvm-project/llvm/branches/release_XY
$ svn copy https://llvm.org/svn/llvm-project/cfe/trunk \
https://llvm.org/svn/llvm-project/cfe/branches/release_XY
$ svn copy https://llvm.org/svn/llvm-project/dragonegg/trunk \
https://llvm.org/svn/llvm-project/dragonegg/branches/release_XY
$ svn copy https://llvm.org/svn/llvm-project/test-suite/trunk \
https://llvm.org/svn/llvm-project/test-suite/branches/release_XY
Advise developers that they may now check their patches into the Subversion tree again.
The Release Manager should switch to the release branch, because all changes to the release will now be done in the branch. The easiest way to do this is to grab a working copy using the following commands:
$ svn co https://llvm.org/svn/llvm-project/llvm/branches/release_XY llvm-X.Y $ svn co https://llvm.org/svn/llvm-project/cfe/branches/release_XY clang-X.Y $ svn co https://llvm.org/svn/llvm-project/dragonegg/branches/release_XY dragonegg-X.Y $ svn co https://llvm.org/svn/llvm-project/test-suite/branches/release_XY test-suite-X.Y
After creating the LLVM release branch, update the release branches' autoconf and configure.ac versions from 'X.Ysvn' to 'X.Y'. Update it on mainline as well to be the next version ('X.Y+1svn'). Regenerate the configure scripts for both llvm and the test-suite.
In addition, the version numbers of all the Bugzilla components must be updated for the next release.
Create release candidates for llvm, clang, dragonegg, and the LLVM test-suite by tagging the branch with the respective release candidate number. For instance, to create Release Candidate 1 you would issue the following commands:
$ svn mkdir https://llvm.org/svn/llvm-project/llvm/tags/RELEASE_XY
$ svn copy https://llvm.org/svn/llvm-project/llvm/branches/release_XY \
https://llvm.org/svn/llvm-project/llvm/tags/RELEASE_XY/rc1
$ svn mkdir https://llvm.org/svn/llvm-project/cfe/tags/RELEASE_XY
$ svn copy https://llvm.org/svn/llvm-project/cfe/branches/release_XY \
https://llvm.org/svn/llvm-project/cfe/tags/RELEASE_XY/rc1
$ svn mkdir https://llvm.org/svn/llvm-project/dragonegg/tags/RELEASE_XY
$ svn copy https://llvm.org/svn/llvm-project/dragonegg/branches/release_XY \
https://llvm.org/svn/llvm-project/dragonegg/tags/RELEASE_XY/rc1
$ svn mkdir https://llvm.org/svn/llvm-project/test-suite/tags/RELEASE_XY
$ svn copy https://llvm.org/svn/llvm-project/test-suite/branches/release_XY \
https://llvm.org/svn/llvm-project/test-suite/tags/RELEASE_XY/rc1
Similarly, Release Candidate 2 would be named RC2 and so on. This keeps a permanent copy of the release candidate around for people to export and build as they wish. The final released sources will be tagged in the RELEASE_XY directory as Final (c.f. Tag the LLVM Final Release).
The Release Manager may supply pre-packaged source tarballs for users. This can be done with the following commands:
$ svn export https://llvm.org/svn/llvm-project/llvm/tags/RELEASE_XY/rc1 llvm-X.Yrc1 $ svn export https://llvm.org/svn/llvm-project/cfe/tags/RELEASE_XY/rc1 clang-X.Yrc1 $ svn export https://llvm.org/svn/llvm-project/dragonegg/tags/RELEASE_XY/rc1 dragonegg-X.Yrc1 $ svn export https://llvm.org/svn/llvm-project/test-suite/tags/RELEASE_XY/rc1 llvm-test-X.Yrc1 $ tar -cvf - llvm-X.Yrc1 | gzip > llvm-X.Yrc1.src.tar.gz $ tar -cvf - clang-X.Yrc1 | gzip > clang-X.Yrc1.src.tar.gz $ tar -cvf - dragonegg-X.Yrc1 | gzip > dragonegg-X.Yrc1.src.tar.gz $ tar -cvf - llvm-test-X.Yrc1 | gzip > llvm-test-X.Yrc1.src.tar.gz
The builds of llvm, clang, and dragonegg must be free of errors and warnings in Debug, Release+Asserts, and Release builds. If all builds are clean, then the release passes Build Qualification.
The make options for building the different modes:
| Mode | Options |
|---|---|
| Debug | ENABLE_OPTIMIZED=0 |
| Release+Asserts | ENABLE_OPTIMIZED=1 |
| Release | ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1 |
Build Debug, Release+Asserts, and Release versions of llvm on all supported platforms. Directions to build llvm are here.
Creating the clang binary distribution (Debug/Release+Asserts/Release) requires performing the following steps for each supported platform:
The table below specifies which compilers are used for each Arch/OS combination when qualifying the build of llvm, clang, and dragonegg.
| 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 |
A release is qualified when it has no regressions from the previous release (or baseline). Regressions are related to correctness first and performance second. (We may tolerate some minor performance regressions if they are deemed necessary for the general quality of the compiler.)
Regressions are new failures in the set of tests that are used to qualify each product and only include things on the list. Every release will have some bugs in it. It is the reality of developing a complex piece of software. 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 criteria, but these are the criteria which we found to be most important and which must be satisfied before a release can go out
LLVM is qualified when it has a clean test run without a front-end. And it has no regressions when using either clang or dragonegg with the test-suite from the previous release.
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.
| Architecture | OS | clang baseline | tests |
|---|---|---|---|
| x86-32 | Linux | last release | llvm dejagnu, clang tests, test-suite (including spec) |
| x86-32 | FreeBSD | last release | llvm dejagnu, clang tests, test-suite |
| x86-32 | mingw | none | QT |
| x86-64 | Mac OS 10.X | last release | llvm dejagnu, clang tests, test-suite (including spec) |
| x86-64 | Linux | last release | llvm dejagnu, clang tests, test-suite (including spec) |
| x86-64 | FreeBSD | last release | llvm dejagnu, clang tests, test-suite |
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. Ask that all LLVM developers test the release in 2 ways:
Ask LLVM developers to submit the test suite report and make check results to the list. 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 is at least clean.
During the first round of testing, all regressions must be fixed before the second release candidate is tagged.
If this is the second round of testing, 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.
Below are the rules regarding patching the release branch:
Patches applied to the release branch may only be 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. 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 critical regressions may be applied.
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.
Review the documentation 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 avaiable from Subversion and changes in basic system requirements. Merge both changes from mainline into the release branch.
Tag the final release sources using the following procedure:
$ svn copy https://llvm.org/svn/llvm-project/llvm/branches/release_XY \
https://llvm.org/svn/llvm-project/llvm/tags/RELEASE_XY/Final
$ svn copy https://llvm.org/svn/llvm-project/cfe/branches/release_XY \
https://llvm.org/svn/llvm-project/cfe/tags/RELEASE_XY/Final
$ svn copy https://llvm.org/svn/llvm-project/dragonegg/branches/release_XY \
https://llvm.org/svn/llvm-project/dragonegg/tags/RELEASE_XY/Final
$ svn copy https://llvm.org/svn/llvm-project/test-suite/branches/release_XY \
https://llvm.org/svn/llvm-project/test-suite/tags/RELEASE_XY/Final
The LLVM demo page must be updated to use the new release. This consists of using the new clang binary and building LLVM.
The website must be updated before the release announcement is sent out. Here is what to do:
Have Chris send out the release announcement when everything is finished.