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 |        | 
 | <div class="doc_title">LLVM Developer Policy</div> | 
 | <ol> | 
 |   <li><a href="#introduction">Introduction</a></li> | 
 |   <li><a href="#policies">Developer Policies</a> | 
 |   <ol> | 
 |     <li><a href="#informed">Stay Informed</a></li> | 
 |     <li><a href="#patches">Making a Patch</a></li> | 
 |     <li><a href="#reviews">Code Reviews</a></li> | 
 |     <li><a href="#owners">Code Owners</a></li> | 
 |     <li><a href="#testcases">Test Cases</a></li> | 
 |     <li><a href="#quality">Quality</a></li> | 
 |     <li><a href="#commitaccess">Obtaining Commit Access</a></li> | 
 |     <li><a href="#newwork">Making a Major Change</a></li> | 
 |     <li><a href="#incremental">Incremental Development</a></li> | 
 |     <li><a href="#attribution">Attribution of Changes</a></li> | 
 |   </ol></li> | 
 |   <li><a href="#clp">Copyright, License, and Patents</a> | 
 |   <ol> | 
 |     <li><a href="#copyright">Copyright</a></li> | 
 |     <li><a href="#license">License</a></li> | 
 |     <li><a href="#patents">Patents</a></li> | 
 |     <li><a href="#devagree">Developer Agreements</a></li> | 
 |   </ol></li> | 
 | </ol> | 
 | <div class="doc_author">Written by the LLVM Oversight Team</div> | 
 |  | 
 | <!--=========================================================================--> | 
 | <div class="doc_section"><a name="introduction">Introduction</a></div> | 
 | <!--=========================================================================--> | 
 | <div class="doc_text"> | 
 | <p>This document contains the LLVM Developer Policy which defines the project's | 
 |    policy towards developers and their contributions. The intent of this policy | 
 |    is to eliminate miscommunication, 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> | 
 | <p>This policy is also designed to accomplish the following objectives:</p> | 
 |  | 
 | <ol> | 
 |   <li>Attract both users and developers to the LLVM project.</li> | 
 |  | 
 |   <li>Make life as simple and easy for contributors as possible.</li> | 
 |  | 
 |   <li>Keep the top of Subversion trees as stable as possible.</li> | 
 | </ol> | 
 |    | 
 | <p>This policy is aimed at frequent contributors to LLVM. People interested in | 
 |    contributing one-off patches can do so in an informal way by sending them to | 
 |    the | 
 |    <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits | 
 |    mailing list</a> and engaging another developer to see it through the | 
 |    process.</p> | 
 | </div> | 
 |  | 
 | <!--=========================================================================--> | 
 | <div class="doc_section"><a name="policies">Developer Policies</a></div> | 
 | <!--=========================================================================--> | 
 | <div class="doc_text"> | 
 | <p>This section contains policies that pertain to frequent LLVM developers.  We | 
 |    always welcome <a href="#patches">one-off patches</a> from people who do not | 
 |    routinely contribute to LLVM, but we expect more from frequent contributors | 
 |    to keep the system as efficient as possible for everyone.  Frequent LLVM | 
 |    contributors are expected to meet the following requirements 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="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">llvmdev</a> email | 
 |   list.  If you are doing anything more than just casual work on LLVM, it is | 
 |   suggested that you also subscribe to the | 
 |   <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a> | 
 |   list and pay attention to changes being made by others.</p> | 
 |  | 
 | <p>We recommend that active developers register an email account with  | 
 |    <a href="http://llvm.org/bugs/">LLVM Bugzilla</a> and preferably subscribe to | 
 |    the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmbugs">llvm-bugs</a> | 
 |    email list to keep track of bugs and enhancements occurring in LLVM.</p> | 
 | </div> | 
 |  | 
 | <!-- _______________________________________________________________________ --> | 
 | <div class="doc_subsection"> <a name="patches">Making a Patch</a></div> | 
 |  | 
 | <div class="doc_text"> | 
 | <p>When making a patch for review, the goal is to make it as easy for the | 
 |    reviewer to read it as possible.  As such, we recommend that you:</p> | 
 |  | 
 | <ol> | 
 |   <li>Make your patch against the Subversion trunk, not a branch, and not an old | 
 |       version of LLVM.  This makes it easy to apply the patch.  For information | 
 |       on how to check out SVN trunk, please see the <a | 
 |       href="GettingStarted.html#checkout">Getting Started Guide</a>.</li> | 
 |          | 
 |   <li>Similarly, patches should be submitted soon after they are generated.  Old | 
 |       patches may not apply correctly if the underlying code changes between the | 
 |       time the patch was created and the time it is applied.</li> | 
 |  | 
 |   <li>Patches should be made with this command: | 
 | <div class="doc_code"> | 
 | <pre> | 
 | svn diff | 
 | </pre> | 
 | </div> | 
 |       or with the utility <tt>utils/mkpatch</tt>, which makes it easy to read | 
 |       the diff.</li> | 
 |  | 
 |   <li>Patches should not include differences in generated code such as the code | 
 |       generated by <tt>autoconf</tt> or <tt>tblgen</tt>. The | 
 |       <tt>utils/mkpatch</tt> utility takes care of this for you.</li> | 
 | </ol> | 
 |    | 
 | <p>When sending a patch to a mailing list, it is a good idea to send it as an | 
 |    <em>attachment</em> to the message, not embedded into the text of the | 
 |    message.  This ensures that your mailer will not mangle the patch when it | 
 |    sends it (e.g. by making whitespace changes or by wrapping lines).</p> | 
 |  | 
 | <p><em>For Thunderbird users:</em> Before submitting a patch, please open  | 
 |    <em>Preferences → Advanced → General → Config Editor</em>, | 
 |    find the key <tt>mail.content_disposition_type</tt>, and set its value to | 
 |    <tt>1</tt>. Without this setting, Thunderbird sends your attachment using | 
 |    <tt>Content-Disposition: inline</tt> rather than <tt>Content-Disposition: | 
 |    attachment</tt>. Apple Mail gamely displays such a file inline, making it | 
 |    difficult to work with for reviewers using that program.</p> | 
 | </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 one way to increase the quality | 
 |    of software. We generally follow these policies:</p> | 
 |  | 
 | <ol> | 
 |   <li>All developers are required to have significant changes reviewed before | 
 |       they are committed to the repository.</li> | 
 |  | 
 |   <li>Code reviews are conducted by email, usually on the llvm-commits | 
 |       list.</li> | 
 |  | 
 |   <li>Code can be reviewed either before it is committed or after.  We expect | 
 |       major changes to be reviewed before being committed, but smaller changes | 
 |       (or changes where the developer owns the component) can be reviewed after | 
 |       commit.</li> | 
 |  | 
 |   <li>The developer responsible for a code change is also responsible for making | 
 |       all necessary review-related changes.</li> | 
 |  | 
 |   <li>Code review can be an iterative process, which continues until the patch | 
 |       is ready to be committed.</li> | 
 | </ol> | 
 |    | 
 | <p>Developers should participate in code reviews as both reviewers and | 
 |    reviewees. If someone is kind enough to review your code, you should return | 
 |    the favor for someone else.  Note that anyone is welcome to review and give | 
 |    feedback on a patch, but only people with Subversion write access can approve | 
 |    it.</p> | 
 | </div> | 
 |  | 
 | <!-- _______________________________________________________________________ --> | 
 | <div class="doc_subsection"> <a name="owners">Code Owners</a></div> | 
 | <div class="doc_text"> | 
 |  | 
 | <p>The LLVM Project relies on two features of its process to maintain rapid | 
 |    development in addition to the high quality of its source base: the | 
 |    combination of code review plus post-commit review for trusted maintainers. | 
 |    Having both is a great way for the project to take advantage of the fact that | 
 |    most people do the right thing most of the time, and only commit patches | 
 |    without pre-commit review when they are confident they are right.</p> | 
 |       | 
 | <p>The trick to this is that the project has to guarantee that all patches that | 
 |    are committed are reviewed after they go in: you don't want everyone to | 
 |    assume someone else will review it, allowing the patch to go unreviewed.  To | 
 |    solve this problem, we have a notion of an 'owner' for a piece of the code. | 
 |    The sole responsibility of a code owner is to ensure that a commit to their | 
 |    area of the code is appropriately reviewed, either by themself or by someone | 
 |    else.  The current code owners are:</p> | 
 |    | 
 | <ol> | 
 |   <li><b>Evan Cheng</b>: Code generator and all targets.</li> | 
 |  | 
 |   <li><b>Doug Gregor</b>: Clang Basic, Lex, Parse, and Sema Libraries.</li> | 
 |  | 
 |   <li><b>Anton Korobeynikov</b>: Exception handling, debug information, and | 
 |       Windows codegen.</li> | 
 |  | 
 |   <li><b>Ted Kremenek</b>: Clang Static Analyzer.</li> | 
 |  | 
 |   <li><b>Chris Lattner</b>: Everything not covered by someone else.</li> | 
 |    | 
 |   <li><b>Duncan Sands</b>: llvm-gcc 4.2.</li> | 
 | </ol> | 
 |    | 
 | <p>Note that code ownership is completely different than reviewers: anyone can | 
 |    review a piece of code, and we welcome code review from anyone who is | 
 |    interested.  Code owners are the "last line of defense" to guarantee that all | 
 |    patches that are committed are actually reviewed.</p> | 
 |  | 
 | <p>Being a code owner is a somewhat unglamorous position, but it is incredibly | 
 |    important for the ongoing success of the project.  Because people get busy, | 
 |    interests change, and unexpected things happen, code ownership is purely | 
 |    opt-in, and anyone can choose to resign their "title" at any time. For now, | 
 |    we do not have an official policy on how one gets elected to be a code | 
 |    owner.</p> | 
 | </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 any bugs fixed and any new | 
 |    features added.  Some tips for getting your testcase approved:</p> | 
 |  | 
 | <ol> | 
 |   <li>All feature and regression test cases are added to the  | 
 |       <tt>llvm/test</tt> directory. The appropriate sub-directory should be | 
 |       selected (see the <a href="TestingGuide.html">Testing Guide</a> for | 
 |       details).</li> | 
 |  | 
 |   <li>Test cases should be written in <a href="LangRef.html">LLVM assembly | 
 |       language</a> unless the feature or regression being tested requires | 
 |       another language (e.g. the bug being fixed or feature being implemented is | 
 |       in the llvm-gcc C++ front-end, in which case it must be written in | 
 |       C++).</li> | 
 |  | 
 |   <li>Test cases, especially for regressions, should be reduced as much as | 
 |       possible, by <a href="Bugpoint.html">bugpoint</a> or manually. 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. Please keep | 
 |       them short.</li> | 
 | </ol> | 
 |    | 
 | <p>Note that llvm/test is designed for regression and small feature tests | 
 |    only. More extensive test cases (e.g., entire applications, benchmarks, etc) | 
 |    should be added to the <tt>llvm-test</tt> test suite.  The llvm-test suite is | 
 |    for coverage (correctness, performance, etc) testing, not feature or | 
 |    regression testing.</p> | 
 | </div> | 
 |  | 
 | <!-- _______________________________________________________________________ --> | 
 | <div class="doc_subsection"> <a name="quality">Quality</a></div> | 
 | <div class="doc_text"> | 
 | <p>The minimum quality standards that any change must satisfy before being | 
 |    committed 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>Bug fixes and new features should <a href="#testcases">include a | 
 |       testcase</a> so we know if the fix/feature ever regresses in the | 
 |       future.</li> | 
 |  | 
 |   <li>Code must pass the dejagnu (<tt>llvm/test</tt>) test suite.</li> | 
 |  | 
 |   <li>The code must not cause regressions on a reasonable subset of llvm-test, | 
 |       where "reasonable" depends on the contributor's judgement and the scope of | 
 |       the change (more invasive changes require more testing). A reasonable | 
 |       subset might be something like | 
 |       "<tt>llvm-test/MultiSource/Benchmarks</tt>".</li> | 
 | </ol> | 
 |  | 
 | <p>Additionally, the committer is responsible for addressing any problems found | 
 |    in the future that the change is responsible for.  For example:</p> | 
 |  | 
 | <ul> | 
 |   <li>The code should compile cleanly on all supported platforms.</li> | 
 |  | 
 |   <li>The changes should not cause any correctness regressions in the | 
 |       <tt>llvm-test</tt> suite and must not cause any major performance | 
 |       regressions.</li> | 
 |  | 
 |   <li>The change set should not cause performance or correctness regressions for | 
 |       the LLVM tools.</li> | 
 |  | 
 |   <li>The changes should not cause performance or correctness regressions in | 
 |       code compiled by LLVM on all applicable targets.</li> | 
 |  | 
 |   <li>You are expected to address any <a href="http://llvm.org/bugs/">bugzilla | 
 |       bugs</a> that result from your change.</li> | 
 | </ul> | 
 |    | 
 | <p>We prefer for this to be handled before submission but understand that it | 
 |    isn't possible to test all of this for every submission.  Our build bots and | 
 |    nightly testing infrastructure normally finds these problems.  A good rule of | 
 |    thumb is to check the nightly testers for regressions the day after your | 
 |    change.  Build bots will directly email you if a group of commits that | 
 |    included yours caused a failure.  You are expected to check the build bot | 
 |    messages to see if they are your fault and, if so, fix the breakage.</p> | 
 |  | 
 | <p>Commits that violate these quality standards (e.g. are very broken) may be | 
 |    reverted. This is necessary when the change blocks other developers from | 
 |    making progress. The developer is welcome to re-commit the change after the | 
 |    problem has been fixed.</p> | 
 | </div> | 
 |  | 
 | <!-- _______________________________________________________________________ --> | 
 | <div class="doc_subsection"> | 
 |   <a name="commitaccess">Obtaining Commit Access</a></div> | 
 | <div class="doc_text"> | 
 |  | 
 | <p>We grant commit access to contributors with a track record of submitting high | 
 |    quality patches.  If you would like commit access, please send an email to | 
 |    <a href="mailto:sabre@nondot.org">Chris</a> with the following | 
 |    information:</p> | 
 |  | 
 | <ol> | 
 |   <li>The user name you want to commit with, e.g. "hacker".</li> | 
 |  | 
 |   <li>The full name and email address you want message to llvm-commits to come | 
 |       from, e.g. "J. Random Hacker <hacker@yoyodyne.com>".</li> | 
 |  | 
 |   <li>A "password hash" of the password you want to use, e.g. "2ACR96qjUqsyM".   | 
 |       Note that you don't ever tell us what your password is, you just give it | 
 |       to us in an encrypted form.  To get this, run "htpasswd" (a utility that | 
 |       comes with apache) in crypt mode (often enabled with "-d"), or find a web | 
 |       page that will do it for you.</li> | 
 | </ol> | 
 |  | 
 | <p>Once you've been granted commit access, you should be able to check out an | 
 |    LLVM tree with an SVN URL of "https://username@llvm.org/..." instead of the | 
 |    normal anonymous URL of "http://llvm.org/...".  The first time you commit | 
 |    you'll have to type in your password.  Note that you may get a warning from | 
 |    SVN about an untrusted key, you can ignore this.  To verify that your commit | 
 |    access works, please do a test commit (e.g. change a comment or add a blank | 
 |    line).  Your first commit to a repository may require the autogenerated email | 
 |    to be approved by a mailing list.  This is normal, and will be done when | 
 |    the mailing list owner has time.</p> | 
 |  | 
 | <p>If you have recently been granted commit access, these policies apply:</p> | 
 |  | 
 | <ol> | 
 |   <li>You are granted <i>commit-after-approval</i> to all parts of LLVM.  To get | 
 |       approval, submit a <a href="#patches">patch</a> to | 
 |       <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>. | 
 |       When approved you may commit it yourself.</li> | 
 |  | 
 |   <li>You are allowed to commit patches without approval which you think are | 
 |       obvious. This is clearly a subjective decision — we simply expect | 
 |       you to use good judgement.  Examples include: fixing build breakage, | 
 |       reverting obviously broken patches, documentation/comment changes, any | 
 |       other minor changes.</li> | 
 |  | 
 |   <li>You are allowed to commit patches without approval to those portions of | 
 |       LLVM that you have contributed or maintain (i.e., 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>Multiple violations of these policies or a single egregious violation may | 
 |       cause commit access to be revoked.</li> | 
 | </ol> | 
 |  | 
 | <p>In any case, your changes are still subject to <a href="#reviews">code | 
 |    review</a> (either before or after they are committed, depending on the | 
 |    nature of the change).  You are encouraged to review other peoples' patches | 
 |    as well, but you aren't required to.</p> | 
 | </div> | 
 |  | 
 | <!-- _______________________________________________________________________ --> | 
 | <div class="doc_subsection"> <a name="newwork">Making a Major Change</a></div> | 
 | <div class="doc_text"> | 
 | <p>When a developer begins a major new project with the aim of contributing it | 
 |    back to LLVM, s/he should inform the community with an email to | 
 |    the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">llvmdev</a> | 
 |    email list, to the extent possible. The reason for this is to: | 
 |  | 
 | <ol> | 
 |   <li>keep the community informed about future changes to LLVM, </li> | 
 |  | 
 |   <li>avoid duplication of effort by preventing multiple parties working on the | 
 |       same thing and not knowing about it, and</li> | 
 |  | 
 |   <li>ensure that any technical issues around the proposed work are discussed | 
 |       and resolved before any significant work is done.</li> | 
 | </ol> | 
 |    | 
 | <p>The design of LLVM is carefully controlled to ensure that all the pieces fit | 
 |    together well and are as consistent as possible. If you plan to make a major | 
 |    change to the way LLVM works or want to add a major new extension, it is a | 
 |    good idea to get consensus with the development community before you start | 
 |    working on it.</p> | 
 |    | 
 | <p>Once the design of the new feature is finalized, the work itself should be | 
 |    done as a series of <a href="#incremental">incremental changes</a>, not as a | 
 |    long-term development branch.</p> | 
 | </div> | 
 |  | 
 | <!-- _______________________________________________________________________ --> | 
 | <div class="doc_subsection"> <a name="incremental">Incremental Development</a> | 
 | </div> | 
 | <div class="doc_text"> | 
 | <p>In the LLVM project, we do all significant changes as a series of incremental | 
 |    patches.  We have a strong dislike for huge changes or long-term development | 
 |    branches.  Long-term development branches have a number of drawbacks:</p> | 
 |  | 
 | <ol> | 
 |   <li>Branches must have mainline merged into them periodically.  If the branch | 
 |       development and mainline development occur in the same pieces of code, | 
 |       resolving merge conflicts can take a lot of time.</li> | 
 |  | 
 |   <li>Other people in the community tend to ignore work on branches.</li> | 
 |  | 
 |   <li>Huge changes (produced when a branch is merged back onto mainline) are | 
 |       extremely difficult to <a href="#reviews">code review</a>.</li> | 
 |  | 
 |   <li>Branches are not routinely tested by our nightly tester | 
 |       infrastructure.</li> | 
 |  | 
 |   <li>Changes developed as monolithic large changes often don't work until the | 
 |       entire set of changes is done.  Breaking it down into a set of smaller | 
 |       changes increases the odds that any of the work will be committed to the | 
 |       main repository.</li> | 
 | </ol>     | 
 |    | 
 | <p>To address these problems, LLVM uses an incremental development style and we | 
 |    require contributors to follow this practice when making a large/invasive | 
 |    change.  Some tips:</p> | 
 |  | 
 | <ul> | 
 |   <li>Large/invasive changes usually have a number of secondary changes that are | 
 |       required before the big change can be made (e.g. API cleanup, etc).  These | 
 |       sorts of changes can often be done before the major change is done, | 
 |       independently of that work.</li> | 
 |  | 
 |   <li>The remaining inter-related work should be decomposed into unrelated sets | 
 |       of changes if possible.  Once this is done, define the first increment and | 
 |       get consensus on what the end goal of the change is.</li> | 
 |  | 
 |   <li>Each change in the set can be stand alone (e.g. to fix a bug), or part of | 
 |       a planned series of changes that works towards the development goal.</li> | 
 |      | 
 |   <li>Each change 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> | 
 |  | 
 |   <li>Often, an independent precursor to a big change is to add a new API and | 
 |       slowly migrate clients to use the new API.  Each change to use the new API | 
 |       is often "obvious" and can be committed without review.  Once the new API | 
 |       is in place and used, it is much easier to replace the underlying | 
 |       implementation of the API.  This implementation change is logically | 
 |       separate from the API change.</li> | 
 | </ul> | 
 |    | 
 | <p>If you are interested in making a large change, and this scares you, please | 
 |    make sure to first <a href="#newwork">discuss the change/gather consensus</a> | 
 |    then ask about the best way to go about making the change.</p> | 
 | </div> | 
 |  | 
 | <!-- _______________________________________________________________________ --> | 
 | <div class="doc_subsection"><a name="attribution">Attribution of  | 
 | Changes</a></div> | 
 | <div class="doc_text"> | 
 | <p>We believe in correct attribution of contributions to their contributors. | 
 |    However, we do not want the source code to be littered with random | 
 |    attributions "this code written by J. Random Hacker" (this is noisy and | 
 |    distracting).  In practice, the revision control system keeps a perfect | 
 |    history of who changed what, and the CREDITS.txt file describes higher-level | 
 |    contributions.  If you commit a patch for someone else, please say "patch | 
 |    contributed by J. Random Hacker!" in the commit message.</p> | 
 |  | 
 | <p>Overall, please do not add contributor names to the source code.</p> | 
 | </div> | 
 |  | 
 | <!--=========================================================================--> | 
 | <div class="doc_section"> | 
 |   <a name="clp">Copyright, License, and Patents</a> | 
 | </div> | 
 | <!--=========================================================================--> | 
 |  | 
 | <div class="doc_text"> | 
 | <p>This section addresses the issues of copyright, license and patents for the | 
 |    LLVM project.  Currently, the University of Illinois is the LLVM copyright | 
 |    holder and the terms of its license to LLVM users and developers is the | 
 |    <a href="http://www.opensource.org/licenses/UoI-NCSA.php">University of  | 
 |    Illinois/NCSA Open Source License</a>.</p> | 
 |  | 
 | <div class="doc_notes"> | 
 | <p style="text-align:center;font-weight:bold">NOTE: This section deals with | 
 |    legal matters but does not provide legal advice.  We are not lawyers, please | 
 |    seek legal counsel from an attorney.</p> | 
 | </div> | 
 | </div> | 
 |  | 
 | <!-- _______________________________________________________________________ --> | 
 | <div class="doc_subsection"><a name="copyright">Copyright</a></div> | 
 | <div class="doc_text"> | 
 | <p>For consistency and ease of management, the project requires the copyright | 
 |    for all LLVM software to be held by a single copyright holder: the University | 
 |    of Illinois (UIUC).</p> | 
 |    | 
 | <p>Although UIUC may eventually reassign the copyright of the software to | 
 |    another entity (e.g. a dedicated non-profit "LLVM Organization") the intent | 
 |    for the project is to always have a single entity hold the copyrights to LLVM | 
 |    at any given time.</p> | 
 |  | 
 | <p>We believe that 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.  The goal of the | 
 |    LLVM project is to always keep the code open and <a href="#license">licensed | 
 |    under a very liberal license</a>.</p> | 
 | </div> | 
 |  | 
 | <!-- _______________________________________________________________________ --> | 
 | <div class="doc_subsection"><a name="license">License</a></div> | 
 | <div class="doc_text"> | 
 | <p>We intend to keep LLVM perpetually open source and to use a liberal open | 
 |    source license. The current license is the | 
 |    <a href="http://www.opensource.org/licenses/UoI-NCSA.php">University of | 
 |    llinois/NCSA Open Source License</a>, which boils down to this:</p> | 
 |  | 
 | <ul> | 
 |   <li>You can freely distribute LLVM.</li> | 
 |  | 
 |   <li>You must retain the copyright notice if you redistribute LLVM.</li> | 
 |  | 
 |   <li>Binaries derived from LLVM must reproduce the copyright notice (e.g.  in | 
 |       an included readme file).</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 <b>allows | 
 |    commercial products to be derived from LLVM</b> with few restrictions and | 
 |    without a requirement for making any derived works also open source (i.e. | 
 |    LLVM's license is not a "copyleft" license like the GPL). We suggest that you | 
 |    read the <a href="http://www.opensource.org/licenses/UoI-NCSA.php">License</a> | 
 |    if further clarification is needed.</p> | 
 |    | 
 | <p>Note that the LLVM Project does distribute llvm-gcc, <b>which is GPL.</b> | 
 |    This means that anything "linked" into llvm-gcc must itself be compatible | 
 |    with the GPL, and must be releasable under the terms of the GPL.  This | 
 |    implies that <b>any code linked into llvm-gcc and distributed to others may | 
 |    be subject to the viral aspects of the GPL</b> (for example, a proprietary | 
 |    code generator linked into llvm-gcc must be made available under the GPL). | 
 |    This is not a problem for code already distributed under a more liberal | 
 |    license (like the UIUC license), and does not affect code generated by | 
 |    llvm-gcc.  It may be a problem if you intend to base commercial development | 
 |    on llvm-gcc without redistributing your source code.</p> | 
 |    | 
 | <p>We have no plans to change the license of LLVM.  If you have questions or | 
 |    comments about the license, please contact the | 
 |    <a href="mailto:llvm-oversight@cs.uiuc.edu">LLVM Oversight Group</a>.</p> | 
 | </div> | 
 |  | 
 | <!-- _______________________________________________________________________ --> | 
 | <div class="doc_subsection"><a name="patents">Patents</a></div> | 
 | <div class="doc_text"> | 
 | <p>To the best of our knowledge, LLVM does not infringe on any patents (we have | 
 |    actually removed code from LLVM in the past that was found to infringe). | 
 |    Having code in LLVM that infringes on patents would violate an important goal | 
 |    of the project by making it hard or impossible to reuse the code for | 
 |    arbitrary purposes (including commercial use).</p> | 
 |     | 
 | <p>When contributing code, we expect contributors to notify us of any potential | 
 |    for patent-related trouble with their changes.  If you or your employer own | 
 |    the rights to a patent and would like to contribute code to LLVM that relies | 
 |    on it, we require that the copyright owner sign an agreement that allows any | 
 |    other user of LLVM to freely use your patent.  Please contact | 
 |    the <a href="mailto:llvm-oversight@cs.uiuc.edu">oversight group</a> for more | 
 |    details.</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, developers agree to assign | 
 |    their copyrights to UIUC for any contribution made so that the entire | 
 |    software base can be managed by a single copyright holder.  This implies that | 
 |    any contributions can be licensed under the license that the project | 
 |    uses.</p> | 
 |  | 
 | <p>When contributing code, you also affirm that you are legally entitled to | 
 |    grant this copyright, personally or on behalf of your employer.  If the code | 
 |    belongs to some other entity, please raise this issue with the oversight | 
 |    group before the code is committed.</p> | 
 | </div> | 
 |  | 
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