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			365 lines
		
	
	
		
			14 KiB
		
	
	
	
		
			ReStructuredText
		
	
	
	
=================================
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How To Release LLVM To The Public
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=================================
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Introduction
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============
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This document contains information about successfully releasing LLVM ---
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including sub-projects: e.g., ``clang`` and ``compiler-rt`` --- to the public.
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It is the Release Manager's responsibility to ensure that a high quality build
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of LLVM is released.
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If you're looking for the document on how to test the release candidates and
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create the binary packages, please refer to the :doc:`ReleaseProcess` instead.
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.. _timeline:
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Release Timeline
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================
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LLVM is released on a time based schedule --- with major releases roughly
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every 6 months.  In between major releases there may be dot releases.
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The release manager will determine if and when to make a dot release based
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on feedback from the community.  Typically, dot releases should be made if
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there are large number of bug-fixes in the stable branch or a critical bug
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has been discovered that affects a large number of users.
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Unless otherwise stated, dot releases will follow the same procedure as
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major releases.
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The release process is roughly as follows:
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* Set code freeze and branch creation date for 6 months after last code freeze
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  date.  Announce release schedule to the LLVM community and update the website.
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* Create release branch and begin release process.
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* Send out release candidate sources for first round of testing.  Testing lasts
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  7-10 days.  During the first round of testing, any regressions found should be
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  fixed.  Patches are merged from mainline into the release branch.  Also, all
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  features need to be completed during this time.  Any features not completed at
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  the end of the first round of testing will be removed or disabled for the
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  release.
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* Generate and send out the second release candidate sources.  Only *critical*
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  bugs found during this testing phase will be fixed.  Any bugs introduced by
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  merged patches will be fixed.  If so a third round of testing is needed.
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* The release notes are updated.
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* Finally, release!
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The release process will be accelerated for dot releases.  If the first round
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of testing finds no critical bugs and no regressions since the last major release,
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then additional rounds of testing will not be required.
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Release Process
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===============
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.. contents::
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   :local:
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Release Administrative Tasks
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----------------------------
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This section describes a few administrative tasks that need to be done for the
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release process to begin.  Specifically, it involves:
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* Creating the release branch,
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* Setting version numbers, and
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* Tagging release candidates for the release team to begin testing.
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Create Release Branch
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^^^^^^^^^^^^^^^^^^^^^
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Branch the Subversion trunk using the following procedure:
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#. Remind developers that the release branching is imminent and to refrain from
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   committing patches that might break the build.  E.g., new features, large
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   patches for works in progress, an overhaul of the type system, an exciting
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   new TableGen feature, etc.
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#. Verify that the current Subversion trunk is in decent shape by
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   examining nightly tester and buildbot results.
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#. Create the release branch for ``llvm``, ``clang``, and other sub-projects,
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   from the last known good revision.  The branch's name is
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   ``release_XY``, where ``X`` is the major and ``Y`` the minor release
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   numbers.  Use ``utils/release/tag.sh`` to tag the release.
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#. Advise developers that they may now check their patches into the Subversion
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   tree again.
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#. The Release Manager should switch to the release branch, because all changes
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   to the release will now be done in the branch.  The easiest way to do this is
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   to grab a working copy using the following commands:
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   ::
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     $ svn co https://llvm.org/svn/llvm-project/llvm/branches/release_XY llvm-X.Y
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     $ svn co https://llvm.org/svn/llvm-project/cfe/branches/release_XY clang-X.Y
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     $ svn co https://llvm.org/svn/llvm-project/test-suite/branches/release_XY test-suite-X.Y
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Update LLVM Version
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^^^^^^^^^^^^^^^^^^^
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After creating the LLVM release branch, update the release branches'
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``autoconf`` and ``configure.ac`` versions from '``X.Ysvn``' to '``X.Y``'.
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Update it on mainline as well to be the next version ('``X.Y+1svn``').
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Regenerate the configure scripts for both ``llvm`` and the ``test-suite``.
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In addition, the version numbers of all the Bugzilla components must be updated
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for the next release.
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Tagging the LLVM Release Candidates
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Tag release candidates using the tag.sh script in utils/release.
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::
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  $ ./tag.sh -release X.Y.Z -rc $RC
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The Release Manager may supply pre-packaged source tarballs for users.  This can
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be done with the export.sh script in utils/release.
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::
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  $ ./export.sh -release X.Y.Z -rc $RC
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This will generate source tarballs for each LLVM project being validated, which
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can be uploaded to the website for further testing.
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Build Clang Binary Distribution
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Creating the ``clang`` binary distribution requires following the instructions
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:doc:`here <ReleaseProcess>`.
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That process will perform both Release+Asserts and Release builds but only
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pack the Release build for upload. You should use the Release+Asserts sysroot,
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normally under ``final/Phase3/Release+Asserts/llvmCore-3.8.1-RCn.install/``,
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for test-suite and run-time benchmarks, to make sure nothing serious has 
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passed through the net. For compile-time benchmarks, use the Release version.
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The minimum required version of the tools you'll need are :doc:`here <GettingStarted>`
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Release Qualification Criteria
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------------------------------
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A release is qualified when it has no regressions from the previous release (or
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baseline).  Regressions are related to correctness first and performance second.
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(We may tolerate some minor performance regressions if they are deemed
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necessary for the general quality of the compiler.)
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More specifically, Clang/LLVM is qualified when it has a clean test with all
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supported sub-projects included (``make check-all``), per target, and it has no
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regressions with the ``test-suite`` in relation to the previous release.
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Regressions are new failures in the set of tests that are used to qualify
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each product and only include things on the list.  Every release will have
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some bugs in it.  It is the reality of developing a complex piece of
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software.  We need a very concrete and definitive release criteria that
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ensures we have monotonically improving quality on some metric.  The metric we
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use is described below.  This doesn't mean that we don't care about other
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criteria, but these are the criteria which we found to be most important and
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which must be satisfied before a release can go out.
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Official Testing
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----------------
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A few developers in the community have dedicated time to validate the release
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candidates and volunteered to be the official release testers for each
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architecture.
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These will be the ones testing, generating and uploading the official binaries
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to the server, and will be the minimum tests *necessary* for the release to
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proceed.
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This will obviously not cover all OSs and distributions, so additional community
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validation is important. However, if community input is not reached before the
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release is out, all bugs reported will have to go on the next stable release.
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The official release managers are:
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* Major releases (X.0): Hans Wennborg
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* Stable releases (X.n): Tom Stellard
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The official release testers are volunteered from the community and have
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consistently validated and released binaries for their targets/OSs. To contact
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them, you should email the ``release-testers@lists.llvm.org`` mailing list.
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The official testers list is in the file ``RELEASE_TESTERS.TXT``, in the ``LLVM``
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repository.
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Community Testing
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-----------------
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Once all testing has been completed and appropriate bugs filed, the release
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candidate tarballs are put on the website and the LLVM community is notified.
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We ask that all LLVM developers test the release in any the following ways:
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#. Download ``llvm-X.Y``, ``llvm-test-X.Y``, and the appropriate ``clang``
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   binary.  Build LLVM.  Run ``make check`` and the full LLVM test suite (``make
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   TEST=nightly report``).
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#. Download ``llvm-X.Y``, ``llvm-test-X.Y``, and the ``clang`` sources.  Compile
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   everything.  Run ``make check`` and the full LLVM test suite (``make
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   TEST=nightly report``).
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#. Download ``llvm-X.Y``, ``llvm-test-X.Y``, and the appropriate ``clang``
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   binary. Build whole programs with it (ex. Chromium, Firefox, Apache) for
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   your platform.
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#. Download ``llvm-X.Y``, ``llvm-test-X.Y``, and the appropriate ``clang``
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   binary. Build *your* programs with it and check for conformance and
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   performance regressions.
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#. Run the :doc:`release process <ReleaseProcess>`, if your platform is
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   *different* than that which is officially supported, and report back errors
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   only if they were not reported by the official release tester for that
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   architecture.
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We also ask that the OS distribution release managers test their packages with
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the first candidate of every release, and report any *new* errors in Bugzilla.
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If the bug can be reproduced with an unpatched upstream version of the release
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candidate (as opposed to the distribution's own build), the priority should be
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release blocker.
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During the first round of testing, all regressions must be fixed before the
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second release candidate is tagged.
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In the subsequent stages, the testing is only to ensure that bug
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fixes previously merged in have not created new major problems. *This is not
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the time to solve additional and unrelated bugs!* If no patches are merged in,
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the release is determined to be ready and the release manager may move onto the
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next stage.
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Reporting Regressions
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---------------------
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Every regression that is found during the tests (as per the criteria above),
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should be filled in a bug in Bugzilla with the priority *release blocker* and
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blocking a specific release.
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To help manage all the bugs reported and which ones are blockers or not, a new
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"[meta]" bug should be created and all regressions *blocking* that Meta. Once
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all blockers are done, the Meta can be closed.
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If a bug can't be reproduced, or stops being a blocker, it should be removed
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from the Meta and its priority decreased to *normal*. Debugging can continue,
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but on trunk.
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Release Patch Rules
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-------------------
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Below are the rules regarding patching the release branch:
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#. Patches applied to the release branch may only be applied by the release
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   manager, the official release testers or the code owners with approval from
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   the release manager.
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#. During the first round of testing, patches that fix regressions or that are
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   small and relatively risk free (verified by the appropriate code owner) are
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   applied to the branch.  Code owners are asked to be very conservative in
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   approving patches for the branch.  We reserve the right to reject any patch
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   that does not fix a regression as previously defined.
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#. During the remaining rounds of testing, only patches that fix critical
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   regressions may be applied.
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#. For dot releases all patches must maintain both API and ABI compatibility with
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   the previous major release.  Only bug-fixes will be accepted.
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Merging Patches
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^^^^^^^^^^^^^^^
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The ``utils/release/merge.sh`` script can be used to merge individual revisions
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into any one of the llvm projects. To merge revision ``$N`` into project
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``$PROJ``, do:
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#. ``svn co https://llvm.org/svn/llvm-project/$PROJ/branches/release_XX
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   $PROJ.src``
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#. ``$PROJ.src/utils/release/merge.sh --proj $PROJ --rev $N``
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#. Run regression tests.
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#. ``cd $PROJ.src``. Run the ``svn commit`` command printed out by ``merge.sh``
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   in step 2.
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Release Final Tasks
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-------------------
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The final stages of the release process involves tagging the "final" release
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branch, updating documentation that refers to the release, and updating the
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demo page.
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Update Documentation
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^^^^^^^^^^^^^^^^^^^^
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Review the documentation and ensure that it is up to date.  The "Release Notes"
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must be updated to reflect new features, bug fixes, new known issues, and
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changes in the list of supported platforms.  The "Getting Started Guide" should
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be updated to reflect the new release version number tag available from
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Subversion and changes in basic system requirements.  Merge both changes from
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mainline into the release branch.
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.. _tag:
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Tag the LLVM Final Release
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^^^^^^^^^^^^^^^^^^^^^^^^^^
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Tag the final release sources using the tag.sh script in utils/release.
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::
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  $ ./tag.sh -release X.Y.Z -final
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Update the LLVM Demo Page
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-------------------------
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The LLVM demo page must be updated to use the new release.  This consists of
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using the new ``clang`` binary and building LLVM.
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Update the LLVM Website
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^^^^^^^^^^^^^^^^^^^^^^^
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The website must be updated before the release announcement is sent out.  Here
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is what to do:
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#. Check out the ``www`` module from Subversion.
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#. Create a new sub-directory ``X.Y`` in the releases directory.
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#. Commit the ``llvm``, ``test-suite``, ``clang`` source and binaries in this
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   new directory.
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#. Copy and commit the ``llvm/docs`` and ``LICENSE.txt`` files into this new
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   directory.  The docs should be built with ``BUILD_FOR_WEBSITE=1``.
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#. Commit the ``index.html`` to the ``release/X.Y`` directory to redirect (use
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   from previous release).
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#. Update the ``releases/download.html`` file with the new release.
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#. Update the ``releases/index.html`` with the new release and link to release
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   documentation.
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#. Finally, update the main page (``index.html`` and sidebar) to point to the
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   new release and release announcement.  Make sure this all gets committed back
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   into Subversion.
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Announce the Release
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^^^^^^^^^^^^^^^^^^^^
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Send an email to the list announcing the release, pointing people to all the
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relevant documentation, download pages and bugs fixed.
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