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			608 lines
		
	
	
		
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| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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|                       "http://www.w3.org/TR/html4/strict.dtd">
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| <html>
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| <head>
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|   <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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|   <title>LLVM Developer Policy</title>
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|   <link rel="stylesheet" href="llvm.css" type="text/css">
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| </head>
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| <body>
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|       
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| <div class="doc_title">LLVM Developer Policy</div>
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| <ol>
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|   <li><a href="#introduction">Introduction</a></li>
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|   <li><a href="#policies">Developer Policies</a>
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|   <ol>
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|     <li><a href="#informed">Stay Informed</a></li>
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|     <li><a href="#patches">Making a Patch</a></li>
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|     <li><a href="#reviews">Code Reviews</a></li>
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|     <li><a href="#owners">Code Owners</a></li>
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|     <li><a href="#testcases">Test Cases</a></li>
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|     <li><a href="#quality">Quality</a></li>
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|     <li><a href="#commitaccess">Obtaining Commit Access</a></li>
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|     <li><a href="#newwork">Making a Major Change</a></li>
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|     <li><a href="#incremental">Incremental Development</a></li>
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|     <li><a href="#attribution">Attribution of Changes</a></li>
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|   </ol></li>
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|   <li><a href="#clp">Copyright, License, and Patents</a>
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|   <ol>
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|     <li><a href="#copyright">Copyright</a></li>
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|     <li><a href="#license">License</a></li>
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|     <li><a href="#patents">Patents</a></li>
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|     <li><a href="#devagree">Developer Agreements</a></li>
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|   </ol></li>
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| </ol>
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| <div class="doc_author">Written by the LLVM Oversight Team</div>
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| 
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| <!--=========================================================================-->
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| <div class="doc_section"><a name="introduction">Introduction</a></div>
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| <!--=========================================================================-->
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| <div class="doc_text">
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| <p>This document contains the LLVM Developer Policy which defines the project's
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|    policy towards developers and their contributions. The intent of this policy
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|    is to eliminate miscommunication, rework, and confusion that might arise from
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|    the distributed nature of LLVM's development.  By stating the policy in clear
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|    terms, we hope each developer can know ahead of time what to expect when
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|    making LLVM contributions.</p>
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| <p>This policy is also designed to accomplish the following objectives:</p>
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| 
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| <ol>
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|   <li>Attract both users and developers to the LLVM project.</li>
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| 
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|   <li>Make life as simple and easy for contributors as possible.</li>
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| 
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|   <li>Keep the top of Subversion trees as stable as possible.</li>
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| </ol>
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|   
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| <p>This policy is aimed at frequent contributors to LLVM. People interested in
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|    contributing one-off patches can do so in an informal way by sending them to
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|    the
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|    <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits
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|    mailing list</a> and engaging another developer to see it through the
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|    process.</p>
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| </div>
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| 
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| <!--=========================================================================-->
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| <div class="doc_section"><a name="policies">Developer Policies</a></div>
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| <!--=========================================================================-->
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| <div class="doc_text">
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| <p>This section contains policies that pertain to frequent LLVM developers.  We
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|    always welcome <a href="#patches">one-off patches</a> from people who do not
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|    routinely contribute to LLVM, but we expect more from frequent contributors
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|    to keep the system as efficient as possible for everyone.  Frequent LLVM
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|    contributors are expected to meet the following requirements in order for
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|    LLVM to maintain a high standard of quality.<p>
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| </div>
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| 
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| <!-- _______________________________________________________________________ -->
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| <div class="doc_subsection"> <a name="informed">Stay Informed</a> </div>
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| <div class="doc_text">
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| <p>Developers should stay informed by reading at least the 
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|    <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">llvmdev</a> email
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|   list.  If you are doing anything more than just casual work on LLVM, it is
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|   suggested that you also subscribe to the
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|   <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>
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|   list and pay attention to changes being made by others.</p>
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| 
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| <p>We recommend that active developers register an email account with 
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|    <a href="http://llvm.org/bugs/">LLVM Bugzilla</a> and preferably subscribe to
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|    the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmbugs">llvm-bugs</a>
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|    email list to keep track of bugs and enhancements occurring in LLVM.</p>
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| </div>
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| 
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| <!-- _______________________________________________________________________ -->
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| <div class="doc_subsection"> <a name="patches">Making a Patch</a></div>
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| 
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| <div class="doc_text">
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| <p>When making a patch for review, the goal is to make it as easy for the
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|    reviewer to read it as possible.  As such, we recommend that you:</p>
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| 
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| <ol>
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|   <li>Make your patch against the Subversion trunk, not a branch, and not an old
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|       version of LLVM.  This makes it easy to apply the patch.  For information
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|       on how to check out SVN trunk, please see the <a
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|       href="GettingStarted.html#checkout">Getting Started Guide</a>.</li>
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|         
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|   <li>Similarly, patches should be submitted soon after they are generated.  Old
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|       patches may not apply correctly if the underlying code changes between the
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|       time the patch was created and the time it is applied.</li>
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| 
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|   <li>Patches should be made with this command:
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| <div class="doc_code">
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| <pre>
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| svn diff
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| </pre>
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| </div>
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|       or with the utility <tt>utils/mkpatch</tt>, which makes it easy to read
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|       the diff.</li>
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| 
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|   <li>Patches should not include differences in generated code such as the code
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|       generated by <tt>autoconf</tt> or <tt>tblgen</tt>. The
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|       <tt>utils/mkpatch</tt> utility takes care of this for you.</li>
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| </ol>
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|   
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| <p>When sending a patch to a mailing list, it is a good idea to send it as an
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|    <em>attachment</em> to the message, not embedded into the text of the
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|    message.  This ensures that your mailer will not mangle the patch when it
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|    sends it (e.g. by making whitespace changes or by wrapping lines).</p>
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| 
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| <p><em>For Thunderbird users:</em> Before submitting a patch, please open 
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|    <em>Preferences → Advanced → General → Config Editor</em>,
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|    find the key <tt>mail.content_disposition_type</tt>, and set its value to
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|    <tt>1</tt>. Without this setting, Thunderbird sends your attachment using
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|    <tt>Content-Disposition: inline</tt> rather than <tt>Content-Disposition:
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|    attachment</tt>. Apple Mail gamely displays such a file inline, making it
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|    difficult to work with for reviewers using that program.</p>
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| </div>
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| 
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| <!-- _______________________________________________________________________ -->
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| <div class="doc_subsection"> <a name="reviews">Code Reviews</a></div>
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| <div class="doc_text">
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| <p>LLVM has a code review policy. Code review is one way to increase the quality
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|    of software. We generally follow these policies:</p>
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| 
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| <ol>
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|   <li>All developers are required to have significant changes reviewed before
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|       they are committed to the repository.</li>
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| 
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|   <li>Code reviews are conducted by email, usually on the llvm-commits
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|       list.</li>
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| 
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|   <li>Code can be reviewed either before it is committed or after.  We expect
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|       major changes to be reviewed before being committed, but smaller changes
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|       (or changes where the developer owns the component) can be reviewed after
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|       commit.</li>
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| 
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|   <li>The developer responsible for a code change is also responsible for making
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|       all necessary review-related changes.</li>
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| 
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|   <li>Code review can be an iterative process, which continues until the patch
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|       is ready to be committed.</li>
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| </ol>
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|   
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| <p>Developers should participate in code reviews as both reviewers and
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|    reviewees. If someone is kind enough to review your code, you should return
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|    the favor for someone else.  Note that anyone is welcome to review and give
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|    feedback on a patch, but only people with Subversion write access can approve
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|    it.</p>
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| </div>
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| 
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| <!-- _______________________________________________________________________ -->
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| <div class="doc_subsection"> <a name="owners">Code Owners</a></div>
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| <div class="doc_text">
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| 
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| <p>The LLVM Project relies on two features of its process to maintain rapid
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|    development in addition to the high quality of its source base: the
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|    combination of code review plus post-commit review for trusted maintainers.
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|    Having both is a great way for the project to take advantage of the fact that
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|    most people do the right thing most of the time, and only commit patches
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|    without pre-commit review when they are confident they are right.</p>
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|      
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| <p>The trick to this is that the project has to guarantee that all patches that
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|    are committed are reviewed after they go in: you don't want everyone to
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|    assume someone else will review it, allowing the patch to go unreviewed.  To
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|    solve this problem, we have a notion of an 'owner' for a piece of the code.
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|    The sole responsibility of a code owner is to ensure that a commit to their
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|    area of the code is appropriately reviewed, either by themself or by someone
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|    else.  The current code owners are:</p>
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|   
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| <ol>
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|   <li><b>Evan Cheng</b>: Code generator and all targets.</li>
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| 
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|   <li><b>Doug Gregor</b>: Clang Basic, Lex, Parse, and Sema Libraries.</li>
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| 
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|   <li><b>Anton Korobeynikov</b>: Exception handling, debug information, and
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|       Windows codegen.</li>
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| 
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|   <li><b>Ted Kremenek</b>: Clang Static Analyzer.</li>
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| 
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|   <li><b>Chris Lattner</b>: Everything not covered by someone else.</li>
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|   
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|   <li><b>Duncan Sands</b>: llvm-gcc 4.2.</li>
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| </ol>
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|   
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| <p>Note that code ownership is completely different than reviewers: anyone can
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|    review a piece of code, and we welcome code review from anyone who is
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|    interested.  Code owners are the "last line of defense" to guarantee that all
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|    patches that are committed are actually reviewed.</p>
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| 
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| <p>Being a code owner is a somewhat unglamorous position, but it is incredibly
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|    important for the ongoing success of the project.  Because people get busy,
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|    interests change, and unexpected things happen, code ownership is purely
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|    opt-in, and anyone can choose to resign their "title" at any time. For now,
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|    we do not have an official policy on how one gets elected to be a code
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|    owner.</p>
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| </div>
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| 
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| <!-- _______________________________________________________________________ -->
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| <div class="doc_subsection"> <a name="testcases">Test Cases</a></div>
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| <div class="doc_text">
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| <p>Developers are required to create test cases for any bugs fixed and any new
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|    features added.  Some tips for getting your testcase approved:</p>
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| 
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| <ol>
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|   <li>All feature and regression test cases are added to the 
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|       <tt>llvm/test</tt> directory. The appropriate sub-directory should be
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|       selected (see the <a href="TestingGuide.html">Testing Guide</a> for
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|       details).</li>
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| 
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|   <li>Test cases should be written in <a href="LangRef.html">LLVM assembly
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|       language</a> unless the feature or regression being tested requires
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|       another language (e.g. the bug being fixed or feature being implemented is
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|       in the llvm-gcc C++ front-end, in which case it must be written in
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|       C++).</li>
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| 
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|   <li>Test cases, especially for regressions, should be reduced as much as
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|       possible, by <a href="Bugpoint.html">bugpoint</a> or manually. It is
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|       unacceptable to place an entire failing program into <tt>llvm/test</tt> as
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|       this creates a <i>time-to-test</i> burden on all developers. Please keep
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|       them short.</li>
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| </ol>
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|   
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| <p>Note that llvm/test is designed for regression and small feature tests
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|    only. More extensive test cases (e.g., entire applications, benchmarks, etc)
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|    should be added to the <tt>llvm-test</tt> test suite.  The llvm-test suite is
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|    for coverage (correctness, performance, etc) testing, not feature or
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|    regression testing.</p>
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| </div>
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| 
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| <!-- _______________________________________________________________________ -->
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| <div class="doc_subsection"> <a name="quality">Quality</a></div>
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| <div class="doc_text">
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| <p>The minimum quality standards that any change must satisfy before being
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|    committed to the main development branch are:</p>
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| 
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| <ol>
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|   <li>Code must adhere to the <a href="CodingStandards.html">LLVM Coding
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|       Standards</a>.</li>
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| 
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|   <li>Code must compile cleanly (no errors, no warnings) on at least one
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|       platform.</li>
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| 
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|   <li>Bug fixes and new features should <a href="#testcases">include a
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|       testcase</a> so we know if the fix/feature ever regresses in the
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|       future.</li>
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| 
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|   <li>Code must pass the dejagnu (<tt>llvm/test</tt>) test suite.</li>
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| 
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|   <li>The code must not cause regressions on a reasonable subset of llvm-test,
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|       where "reasonable" depends on the contributor's judgement and the scope of
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|       the change (more invasive changes require more testing). A reasonable
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|       subset might be something like
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|       "<tt>llvm-test/MultiSource/Benchmarks</tt>".</li>
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| </ol>
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| 
 | |
| <p>Additionally, the committer is responsible for addressing any problems found
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|    in the future that the change is responsible for.  For example:</p>
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| 
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| <ul>
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|   <li>The code should compile cleanly on all supported platforms.</li>
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| 
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|   <li>The changes should not cause any correctness regressions in the
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|       <tt>llvm-test</tt> suite and must not cause any major performance
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|       regressions.</li>
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| 
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|   <li>The change set should not cause performance or correctness regressions for
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|       the LLVM tools.</li>
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| 
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|   <li>The changes should not cause performance or correctness regressions in
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|       code compiled by LLVM on all applicable targets.</li>
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| 
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|   <li>You are expected to address any <a href="http://llvm.org/bugs/">bugzilla
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|       bugs</a> that result from your change.</li>
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| </ul>
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|   
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| <p>We prefer for this to be handled before submission but understand that it
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|    isn't possible to test all of this for every submission.  Our build bots and
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|    nightly testing infrastructure normally finds these problems.  A good rule of
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|    thumb is to check the nightly testers for regressions the day after your
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|    change.  Build bots will directly email you if a group of commits that
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|    included yours caused a failure.  You are expected to check the build bot
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|    messages to see if they are your fault and, if so, fix the breakage.</p>
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| 
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| <p>Commits that violate these quality standards (e.g. are very broken) may be
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|    reverted. This is necessary when the change blocks other developers from
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|    making progress. The developer is welcome to re-commit the change after the
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|    problem has been fixed.</p>
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| </div>
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| 
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| <!-- _______________________________________________________________________ -->
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| <div class="doc_subsection">
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|   <a name="commitaccess">Obtaining Commit Access</a></div>
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| <div class="doc_text">
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| 
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| <p>We grant commit access to contributors with a track record of submitting high
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|    quality patches.  If you would like commit access, please send an email to
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|    <a href="mailto:sabre@nondot.org">Chris</a> with the following
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|    information:</p>
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| 
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| <ol>
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|   <li>The user name you want to commit with, e.g. "hacker".</li>
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| 
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|   <li>The full name and email address you want message to llvm-commits to come
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|       from, e.g. "J. Random Hacker <hacker@yoyodyne.com>".</li>
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| 
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|   <li>A "password hash" of the password you want to use, e.g. "2ACR96qjUqsyM".  
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|       Note that you don't ever tell us what your password is, you just give it
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|       to us in an encrypted form.  To get this, run "htpasswd" (a utility that
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|       comes with apache) in crypt mode (often enabled with "-d"), or find a web
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|       page that will do it for you.</li>
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| </ol>
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| 
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| <p>Once you've been granted commit access, you should be able to check out an
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|    LLVM tree with an SVN URL of "https://username@llvm.org/..." instead of the
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|    normal anonymous URL of "http://llvm.org/...".  The first time you commit
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|    you'll have to type in your password.  Note that you may get a warning from
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|    SVN about an untrusted key, you can ignore this.  To verify that your commit
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|    access works, please do a test commit (e.g. change a comment or add a blank
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|    line).  Your first commit to a repository may require the autogenerated email
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|    to be approved by a mailing list.  This is normal, and will be done when
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|    the mailing list owner has time.</p>
 | |
| 
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| <p>If you have recently been granted commit access, these policies apply:</p>
 | |
| 
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| <ol>
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|   <li>You are granted <i>commit-after-approval</i> to all parts of LLVM.  To get
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|       approval, submit a <a href="#patches">patch</a> to
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|       <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>.
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|       When approved you may commit it yourself.</li>
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| 
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|   <li>You are allowed to commit patches without approval which you think are
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|       obvious. This is clearly a subjective decision — we simply expect
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|       you to use good judgement.  Examples include: fixing build breakage,
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|       reverting obviously broken patches, documentation/comment changes, any
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|       other minor changes.</li>
 | |
| 
 | |
|   <li>You are allowed to commit patches without approval to those portions of
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|       LLVM that you have contributed or maintain (i.e., have been assigned
 | |
|       responsibility for), with the proviso that such commits must not break the
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|       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
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|       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
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|    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
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|    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>
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|   <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
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|    together well and are as consistent as possible. If you plan to make a major
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|    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>
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|   <li>Branches must have mainline merged into them periodically.  If the branch
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|       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
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|       entire set of changes is done.  Breaking it down into a set of smaller
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|       changes increases the odds that any of the work will be committed to the
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|       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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|   Written by the 
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|   <a href="mailto:llvm-oversight@cs.uiuc.edu">LLVM Oversight Group</a><br>
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