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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title>LLVM Developer Policy</title>
<link rel="stylesheet" href="llvm.css" type="text/css">
</head>
<body>
<div class="doc_warning">DRAFT Only. DRAFT Only. DRAFT Only. DRAFT Only.</div>
<div class="doc_title">LLVM Developer Policy</div>
<table class="layout"><tr class="layout"><td class="layout">
<h2>Contents</h2>
<ol>
<li><a href="#overview">Overview</a></li>
<li><a href="#terms">Terminology</a></li>
<li><a href="#candl">Copyright and License</a>
<ol>
<li><a href="#copyright">Copyright</a></li>
<li><a href="#license">License</a></li>
<li><a href="#devagree">Developer Agreements</a></li>
</ol></li>
<li><a href="#general">General Policies</a>
<ol>
<li><a href="#informed">Stay Informed</a> </li>
<li><a href="#newwork">Starting New Work</a></li>
<li><a href="#reviews">Code Reviews</a></li>
<li><a href="#incremental">Incremental Development</a></li>
<li><a href="#quality">Quality</a></li>
<li><a href="#testcases">Test Cases</a></li>
</ol></li>
<li><a href="#patches">Patch Policies</a>
<ol>
<li><a href="#p_form">Patch Form</a></li>
<li><a href="#p_testing">Patch Testing</a></li>
<li><a href="#p_submission">Patch Submission</a></li>
<li><a href="#p_after">After Submission</a></li>
<li><a href="#c_access">Obtaining Commit Access</a></li>
<li><a href="#c_new">New Committers</a></li>
</ol></li>
</ol>
<div class="doc_author">Written by LLVM Oversight Team</div>
</td><td class="layout">
<!--=========================================================================-->
<div class="doc_section"><a name="overview">Overview</a></div>
<!--=========================================================================-->
<div class="doc_text">
<p>This document contains the LLVM Developer Policy which defines the
project's policy towards developer's and their contributions. The intent of
this policy is to eliminate mis-communication, rework, and confusion that
might arise from the distributed nature of LLVM's development. By stating
the policy in clear terms, we hope each developer can know ahead of time
what to expect when making LLVM contributions.</p>
</div>
<!--=========================================================================-->
<div class="doc_section"><a name="terms">Terminology</a></div>
<!--=========================================================================-->
<div class="doc_text">
<p>So that the policies defined in the next sections are clear, we first
define some terms here.</p>
<dl>
<dt><a name="t_change">Change</a></dt>
<dd>Any modification to LLVM including documentation, tests, build system,
etc. either in <a href="#t_patch">patch</a> or
<a href="#t_commit">commit</a> form.</dd>
<dt><a name="t_commit">Commit</a><dt>
<dd>A <a href="t_change">change</a> submitted directly to LLVM software
respository via the <tt>cvs commit</tt> command.</dd>
<dt><a name="t_developer">Developer</a></dt>
<dd>Anyone who submits a <a href="#t_change">change</a> to LLVM.</dd>
<dt><a name="t_inrement">Increment</a></dt>
<dd>A <a href="#t_change">change</a> or set of changes, whether by
<a href="#t_patch">patch</a> or <a href="#t_commit">commit</a>, that are
related by a single common purpose. Increments are atomic as they
leave LLVM in a stable state (both compiling and working properly).</dd>
<dt><a name="t_must">Must</a></dt>
<dd>When used in a policy statement, the term <i>must</i> implies a
non-optional requirement on the developer.</dd>
<dt><a name="t_patch">Patch</a></dt>
<dd>A <a href="#t_change">change</a> submitted by email in patch (diff)
format generated by the <tt>cvs diff</tt> command.</dd>
<dt><a name="t_should">Should</a></dt>
<dd>When used in a policy statement, the term <i>should</i> implies a
recommended but optional requirement on the developer.</dd>
</dl>
</div>
</td></tr></table>
<!--=========================================================================-->
<div class="doc_section"><a name="candl">Copyright and License</a></div>
<!--=========================================================================-->
<div class="doc_text">
<p>We address here the issues of copyright and license for the LLVM project.
A copyright is literally the "right to copy". It is a set of exclusive rights
granted to a party regulating the particular expression of information.
In this case, the information is LLVM. A license is something granted by a
copyright holder to other parties that controls the use of the information
by them. Currently, the University of Illinois is the LLVM copyright holder
and the terms of its license to LLVM users and developers is the
University of Illinois Open Source License (see LICENSE.txt).</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"><a name="copyright">Copyright</a></div>
<div class="doc_text">
<p>The LLVM project believes in correct attribution of contributions to
their contributors. Developers should, therefore, place their name at the
top of any source file they originate and list their contributions in the
CREDITS.TXT file. Furthermore, correct attribution of submitted patches
should be made in the commit comments.</p>
<p>However, for consistency and ease of management, the project requires the
copyright for all LLVM software to be held by a single copyright holder.
Although UIUC may assign the copyright of the software to another entity,
the intent for the project is to always have a single entity hold the copy
rights to LLVM at any given time.
<p>Having multiple copyright holders for various portions of LLVM is
problematic in the management of the software. Having a single copyright
holder is in the best interests of all developers and users as it greatly
reduces the managerial burden for any kind of administrative or technical
decisions about LLVM.</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"><a name="license">License</a></div>
<div class="doc_text">
<p>LLVM licensing decisions will be made by the LLVM Oversight Group. Any
issues, comments or suggestions with the licensing should be sent to
<a href="mailto:oversight@llvm.org">oversight@llvm.org</a>.</p>
<p>The LLVM Oversight Group intends to keep LLVM perpetually open source
and to use liberal open source licenses. The current license is the
University of Illinois Open Source License (see LICENSE.TXT), which boils
down to this:</p>
<ul>
<li>You can freely distribute LLVM.</li>
<li>You must retain the copyright notice if you redistribute.</li>
<li>Binaries derived from LLVM must reproduce the copyright notice.</li>
<li>You can't use our names to promote your LLVM derived products.</li>
<li>There's no warranty on LLVM at all.</li>
</ul>
<p>We believe this fosters the widest adoption of LLVM because it allows
commercial products to be derived from LLVM with few restrictions and
without a requirement for making any derived works also open source. The
intent of the license is to let people use LLVM freely with only the
obligation to be honest about where it came from.</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"><a name="devagree">Developer Agreements</a></div>
<div class="doc_text">
<p>With regards to the LLVM copyright and licensing, developer's agree to:</p>
<ul>
<li>give up their copy rights to any contribution made so that the entire
software base can be managed by a single copyright holder.</li>
<li>allow their contribution(s) to be licensed as open source by the then
current or subsequent license chosen by the LLVM Oversight Group.</li>
<li>not make LLVM available under any other licensing agreement.</li>
</ul>
</div>
<!--=========================================================================-->
<div class="doc_section"><a name="general">General Policies</a></div>
<!--=========================================================================-->
<div class="doc_text">
<p>This section contains policies that pertain generally to LLVM developers.
<p>LLVM Developers are expected to meet the following obligations in order
for LLVM to maintain a high standard of quality<p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="informed">Stay Informed</a> </div>
<div class="doc_text">
<p>Developers should stay informed by reading at least the
<a href="mailto:llvmdev@llvm.org">llvmdev</a> email list. If you are doing
anything more than just casual work on LLVM, it is highly suggested that you
also subscribe to the llvm-commits list and pay attention to changes being
made by others.</p>
<p>Active developers must register an email account with bugzilla
(<a href="http://llvm.org/bugs/">http://llvm.org/bugs/</a>) and preferably
subscribe to the llvm-bugs email list to keep track of bugs occuring in
LLVM.</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="newwork">Starting New Work</a></div>
<div class="doc_text">
<p>When a developer begins new work with the aim of contributing it back to
LLVM, s/he must inform the community with an email to llvm-dev email list,
to the extent possible. The reason for this is to:
<ul>
<li>keep the community informed about future changes to LLVM, </li>
<li>avoid duplication of effort by having multiple parties working on the
same thing and not knowing about it, and</li>
<li>ensure that any issues around the proposed work are discussed and
resolved before any significant work is accomplished.</li>
</ul>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="reviews">Code Reviews</a></div>
<div class="doc_text">
<p>LLVM has a code review policy. Code review is an excellent way to ensure
high quality in the software. The following policies apply:</p>
<ol>
<li>All developers are required to have any significant changes reviewed
before they are committed to the repository.</li>
<li>Code reviews are conducted by email.</li>
<li>Code can be reviewed either before it is committed or after.</li>
<li>The developer responsible for a code change is also responsible for
making all necessary review changes.</li>
<li>Developers should participate in code reviews as both a reviewer and
a reviewee. We don't have a dedicated team of reviewers. If someone is
kind enough to review your code, you should return the favor for someone
else.</li>
</ol>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="incremental">Incremental Development</a>
</div>
<div class="doc_text">
<p>LLVM uses an incremental development style and all developers are expected
to follow this practice. Incremental development is a big key to LLVM's
success and it is essential that developers submit incremental patches. The
following defines the incremental development approach:</p>
<ol>
<li>The first task is to define the increment and get consensus (with the
LLVM development community) on what the end goal of the change is. Making
random small changes that go nowhere is not useful for anyone.</li>
<li>An increment is the smallest patch size necessary to effect one change
in LLVM.</li>
<li>Increments can be stand alone (e.g. to fix a bug), or part of a planned
series of increments towards some development goal.</li>
<li>Increments should be kept as small as possible. This simplifies your
work (into a logical progression), simplifies code review and reduces the
chance that you will get negative feedback on the change. Small increments
also facilitate the maintenance of a high quality code base.</li>
</ol>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="quality">Quality</a></div>
<div class="doc_text">
<p>The minimum quality standards for any change to the main development
branch are:</p>
<ol>
<li>Code must adhere to the
<a href="CodingStandards.html">LLVM Coding Standards</a>.</li>
<li>Code must compile cleanly (no errors, no warnings) on at least one
platform.</li>
<li>Code must pass the deja gnu (llvm/test) test suite.</li>
<li>
</ol>
<p>Additionally, the committer is responsible for all of the following items.
It is considered significantly preferable for all of these items to be
accounted for <i>before</i> the code is submitted for review or committed.</p>
<ol>
<li>Code must compile cleanly on all platforms.</li>
<li>Code must pass the <tt>llvm-test</tt> test suite including
SPEC CINT2000, SPEC CFP2000, SPEC CINT2006, and SPEC CFP2006.</li>
<li>The changesat must not cause performance or correctness regressions
for the LLVM tools.</li>
<li>The changes must not cause performance or correctness regressions in
code compiled with LLVM on all applicable targets.</li>
</ol>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="testcases">Test Cases</a></div>
<div class="doc_text">
<p>Developers are required to create test cases for regressions and new
features and include them with their changes. The following policies
apply:</p>
<ol>
<li>All feature and regression test cases must be added to the
<tt>llvm/test</tt> directory. The appropriate subdirectory should be
selected (see the <a href="TestingGuide.html">Testing Guide</a> for
details.</li>
<li>Test cases should be written in LLVM assembly language unless the
feature or regression being tested requires another language.</li>
<li>Test cases, especially for regressions, should be as reduced as
possible, preferably by
<a href="CommandGuide/html/bugpoint.html">bugpoint</a>. It is unacceptable
to place an entire failing program into <tt>llvm/test</tt> as this creates
a <i>time-to-test</i> burden on all developers. Keep them short!</li>
<li>More extensive test cases (applications, benchmarks, etc.) should be
added to the <tt>llvm-test</tt> test suite, after approval from the
Oversight Group. This test suite is for coverage not features or
regressions.</li>
</ol>
</div>
<!--=========================================================================-->
<div class="doc_section"><a name="patches">Patch Policies</a></div>
<!--=========================================================================-->
<div class="doc_text">
<p>This section contains policies that pertain to submitting patches
to LLVM and committing code to the repository</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="p_form">Patch Form</a></div>
<div class="doc_text">
<p>When submitting a patch, developers must follow these rules:</p>
<ol>
<li>Patches must be made against the CVS HEAD (main development trunk),
not a branch.</li>
<li>Patches must be made with this cvs command:<pre>
cvs diff -Ntdup -5</pre> or with the utility <tt>utils/mkpatch</tt>.</li>
<li>Patches must not include differences in generated code such as the
code generated by <tt>flex</tt>, <tt>bison</tt> or <tt>tblgen</tt>. The
<tt>utils/mkpatch</tt> utility takes care of this for you.</li>
</ol>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="p_testing">Patch Testing</a></div>
<div class="doc_text">
<p>Before a patch is submitted for review, it should be tested to ensure
that:</p>
<ol>
<li>The patch must compile against the CVS HEAD cleanly (zero warnings, zero
errors).</li>
<li>All the llvm/test (Deja Gnu) tests must pass.</li>
<li>All the llvm-test tests must pass on at least one platform.</li>
</ol>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="p_submission">Patch Submission</a></div>
<div class="doc_text">
<p>When a patch is ready to be submitted, these policies apply:</p>
<ol>
<li>Patches should be submitted immediately after they are generated. Stale
patches are unlikely to apply correctly and could be rejected simply due to
age.</li>
<li>Patches must be submitted by e-mail to the
<a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">
llvm-commits</a> list.</li>
</ol>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="p_after">After Submission</a></div>
<div class="doc_text">
<p>After a patch has been submitted, these policies apply:</p>
<ol>
<li>The patch is subject to review by anyone on the llvm-commits email list.
</li>
<li>Any changes recommended by the reviewer must be made by the submitter
of the patch and the patch re-submitted.</li>
<li>If the submitter believes the review comment is in error, a response to
the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">
llvm-commits</a> list should be made explaining why the recommendation
cannot be followed.</li>
</ol>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="p_after">After Commit</a></div>
<div class="doc_text">
<p>After a patch has been committed, these policies apply:</p>
<ol>
<li>The patch is subject to further review by anyone on the llvm-commits
email list.</li>
<li>The patch submitter is responsible for all aspects of the patch per
the <a href="quality">quality policy</a> above.</li>
<li>If the patch is discovered to not meet the
<a href="quality">quality standards</a> standards within a reasonable time
frame (24 hours), it may be subject to reversal.</li>
</ol>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="c_access">Gaining Commit Access</a></div>
<div class="doc_text">
<p>Commit access to the repository is granted according to this policy:</p>
<ol>
<li>Commit access is not granted to anyone unless they specifically ask for
it.</li>
<li>Requests for commit access must be sent to the LLVM Oversight Group at
<a href="mailto:oversight@llvm.org">oversight@llvm.org</a>.</li>
<li>Granting commit access is at the sole discretion of the LLVM Oversight
Group.</li>
<li>Submitting patches to LLVM via the patch policy above will greatly
increase the chance that your request for commit access is granted.</li>
<li>Getting to know the members of the LLVM community (email, IRC, in person
contact, etc.) will also increase your chances.</li>
</ol>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"> <a name="c_new">New Committers</a></div>
<div class="doc_text">
<p>For those who have recently obtained commit access, the following policies
apply:</p>
<ol>
<li>You are granted <i>commit-after-approval</i> to all parts of LLVM.
To get approval, submit a patch to llvm-commits per the patch policies
above. When approved you may commit it yourself.</li>
<li>You are granted <i>commit-without-approavl</i> to those portions of LLVM
that you own (contributed) or maintain (have been assigned responsibility
for), with the proviso that such commits must not break the build. This is
a "trust but verify" policy and commits of this nature are reviewed after
they are committed.</li>
<li>Commits that violate the <a href="quality">quality standards</a> may
be reverted. This is necessary when the change blocks other developers from
making progress. The developers is welcome to re-commit the change after
the problem has been fixed.</li>
<li>Multiple violations of these policies or a single aggregious violation
may cause commit access to be revoked, at the sole discretion of the
LLVM Oversight Group.</li>
</ol>
</div>
<!--=========================================================================-->
<div class="doc_section"><a name="notes">Policy Notes</a></div>
<!--=========================================================================-->
<div class="doc_text">
<p>This section contains some notes on policy topics that need to be
resolved and incorporated into the main body of the document above.</p>
<ol>
<li>When to open a new bug and when to re-use an existing one. For example
PR1158. If the same assertion happens do you open a new bug or reopen
1158?</li>
</ol>
</div>
<!-- *********************************************************************** -->
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