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Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]6 <title>LLVM Developer Policy</title>
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9<body>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]10
11<div class="doc_title">LLVM Developer Policy</div>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]12<ol>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]13 <li><a href="#introduction">Introduction</a></li>
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]14 <li><a href="#policies">Developer Policies</a>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]15 <ol>
Chris Lattner1653fec2007-02-19 05:57:29 +0000[diff] [blame]16 <li><a href="#informed">Stay Informed</a></li>
17 <li><a href="#patches">Making a Patch</a></li>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]18 <li><a href="#reviews">Code Reviews</a></li>
Chris Lattnere268a402007-12-03 19:00:47 +0000[diff] [blame]19 <li><a href="#owners">Code Owners</a></li>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]20 <li><a href="#testcases">Test Cases</a></li>
Chris Lattner1acdc952007-02-19 05:49:11 +0000[diff] [blame]21 <li><a href="#quality">Quality</a></li>
22 <li><a href="#commitaccess">Obtaining Commit Access</a></li>
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]23 <li><a href="#newwork">Making a Major Change</a></li>
24 <li><a href="#incremental">Incremental Development</a></li>
Chris Lattnerc7d954e2007-02-19 05:43:04 +0000[diff] [blame]25 <li><a href="#attribution">Attribution of Changes</a></li>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]26 </ol></li>
Chris Lattner793aa382007-02-19 06:19:16 +0000[diff] [blame]27 <li><a href="#clp">Copyright, License, and Patents</a>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]28 <ol>
29 <li><a href="#copyright">Copyright</a></li>
30 <li><a href="#license">License</a></li>
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]31 <li><a href="#patents">Patents</a></li>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]32 <li><a href="#devagree">Developer Agreements</a></li>
33 </ol></li>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]34</ol>
Chris Lattner2ae49dd2007-02-19 06:24:23 +0000[diff] [blame]35<div class="doc_author">Written by the LLVM Oversight Team</div>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]36
37<!--=========================================================================-->
Reid Spencere7bd7d62007-02-14 17:24:04 +0000[diff] [blame]38<div class="doc_section"><a name="introduction">Introduction</a></div>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]39<!--=========================================================================-->
40<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]41<p>This document contains the LLVM Developer Policy which defines the project's
42 policy towards developers and their contributions. The intent of this policy
43 is to eliminate miscommunication, rework, and confusion that might arise from
44 the distributed nature of LLVM's development. By stating the policy in clear
45 terms, we hope each developer can know ahead of time what to expect when
Chris Lattnerb742ff02010-09-02 00:09:17 +0000[diff] [blame]46 making LLVM contributions. This policy covers all llvm.org subprojects,
47 including Clang, LLDB, etc.</p>
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]48<p>This policy is also designed to accomplish the following objectives:</p>
49
50<ol>
51 <li>Attract both users and developers to the LLVM project.</li>
52
53 <li>Make life as simple and easy for contributors as possible.</li>
54
55 <li>Keep the top of Subversion trees as stable as possible.</li>
56</ol>
Chris Lattnerc7d954e2007-02-19 05:43:04 +0000[diff] [blame]57
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]58<p>This policy is aimed at frequent contributors to LLVM. People interested in
59 contributing one-off patches can do so in an informal way by sending them to
60 the
61 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits
62 mailing list</a> and engaging another developer to see it through the
63 process.</p>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]64</div>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]65
66<!--=========================================================================-->
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]67<div class="doc_section"><a name="policies">Developer Policies</a></div>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]68<!--=========================================================================-->
69<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]70<p>This section contains policies that pertain to frequent LLVM developers. We
71 always welcome <a href="#patches">one-off patches</a> from people who do not
72 routinely contribute to LLVM, but we expect more from frequent contributors
73 to keep the system as efficient as possible for everyone. Frequent LLVM
74 contributors are expected to meet the following requirements in order for
75 LLVM to maintain a high standard of quality.<p>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]76</div>
77
78<!-- _______________________________________________________________________ -->
79<div class="doc_subsection"> <a name="informed">Stay Informed</a> </div>
80<div class="doc_text">
Chris Lattnerb742ff02010-09-02 00:09:17 +0000[diff] [blame]81<p>Developers should stay informed by reading at least the "dev" mailing list
82 for the projects you are interested in, such as
83 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">llvmdev</a> for
84 LLVM, <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">cfe-dev</a>
85 for Clang, or <a
86 href="http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev">lldb-dev</a>
87 for LLDB. If you are doing anything more than just casual work on LLVM, it
88 is suggested that you also subscribe to the "commits" mailing list for the
89 subproject you're interested in, such as
90 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>,
91 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits">cfe-commits</a>,
92 or <a href="http://lists.cs.uiuc.edu/mailman/listinfo/lldb-commits">lldb-commits</a>.
93 Reading the "commits" list and paying attention to changes being made by
94 others is a good way to see what other people are interested in and watching
95 the flow of the project as a whole.</p>
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]96
97<p>We recommend that active developers register an email account with
98 <a href="http://llvm.org/bugs/">LLVM Bugzilla</a> and preferably subscribe to
99 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmbugs">llvm-bugs</a>
Chris Lattnerb742ff02010-09-02 00:09:17 +0000[diff] [blame]100 email list to keep track of bugs and enhancements occurring in LLVM. We
101 really appreciate people who are proactive at catching incoming bugs in their
102 components and dealing with them promptly.</p>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]103</div>
104
105<!-- _______________________________________________________________________ -->
Chris Lattner1653fec2007-02-19 05:57:29 +0000[diff] [blame]106<div class="doc_subsection"> <a name="patches">Making a Patch</a></div>
107
108<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]109<p>When making a patch for review, the goal is to make it as easy for the
110 reviewer to read it as possible. As such, we recommend that you:</p>
Chris Lattner1653fec2007-02-19 05:57:29 +0000[diff] [blame]111
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]112<ol>
113 <li>Make your patch against the Subversion trunk, not a branch, and not an old
Chris Lattner9b96e802009-10-10 21:37:16 +0000[diff] [blame]114 version of LLVM. This makes it easy to apply the patch. For information
115 on how to check out SVN trunk, please see the <a
116 href="GettingStarted.html#checkout">Getting Started Guide</a>.</li>
Chris Lattner1653fec2007-02-19 05:57:29 +0000[diff] [blame]117
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]118 <li>Similarly, patches should be submitted soon after they are generated. Old
119 patches may not apply correctly if the underlying code changes between the
120 time the patch was created and the time it is applied.</li>
121
Dan Gohmanc1076ea2010-08-04 16:07:22 +0000[diff] [blame]122 <li>Patches should be made with <tt>svn diff</tt>, or similar. If you use
123 a different tool, make sure it uses the <tt>diff -u</tt> format and
124 that it doesn't contain clutter which makes it hard to read.</li>
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]125
Dan Gohmanc1076ea2010-08-04 16:07:22 +0000[diff] [blame]126 <li>If you are modifying generated files, such as the top-level
127 <tt>configure</tt> script, please separate out those changes into
128 a separate patch from the rest of your changes.</li>
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]129</ol>
Chris Lattner0cca50c2007-02-19 06:57:16 +0000[diff] [blame]130
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]131<p>When sending a patch to a mailing list, it is a good idea to send it as an
132 <em>attachment</em> to the message, not embedded into the text of the
133 message. This ensures that your mailer will not mangle the patch when it
134 sends it (e.g. by making whitespace changes or by wrapping lines).</p>
135
136<p><em>For Thunderbird users:</em> Before submitting a patch, please open
137 <em>Preferences &#8594; Advanced &#8594; General &#8594; Config Editor</em>,
138 find the key <tt>mail.content_disposition_type</tt>, and set its value to
139 <tt>1</tt>. Without this setting, Thunderbird sends your attachment using
140 <tt>Content-Disposition: inline</tt> rather than <tt>Content-Disposition:
141 attachment</tt>. Apple Mail gamely displays such a file inline, making it
142 difficult to work with for reviewers using that program.</p>
Chris Lattner1653fec2007-02-19 05:57:29 +0000[diff] [blame]143</div>
144
145<!-- _______________________________________________________________________ -->
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]146<div class="doc_subsection"> <a name="reviews">Code Reviews</a></div>
147<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]148<p>LLVM has a code review policy. Code review is one way to increase the quality
149 of software. We generally follow these policies:</p>
Chris Lattner0cca50c2007-02-19 06:57:16 +0000[diff] [blame]150
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]151<ol>
152 <li>All developers are required to have significant changes reviewed before
153 they are committed to the repository.</li>
154
155 <li>Code reviews are conducted by email, usually on the llvm-commits
156 list.</li>
157
158 <li>Code can be reviewed either before it is committed or after. We expect
159 major changes to be reviewed before being committed, but smaller changes
160 (or changes where the developer owns the component) can be reviewed after
161 commit.</li>
162
163 <li>The developer responsible for a code change is also responsible for making
164 all necessary review-related changes.</li>
165
166 <li>Code review can be an iterative process, which continues until the patch
167 is ready to be committed.</li>
168</ol>
169
170<p>Developers should participate in code reviews as both reviewers and
171 reviewees. If someone is kind enough to review your code, you should return
172 the favor for someone else. Note that anyone is welcome to review and give
173 feedback on a patch, but only people with Subversion write access can approve
174 it.</p>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]175</div>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]176
177<!-- _______________________________________________________________________ -->
Chris Lattnere268a402007-12-03 19:00:47 +0000[diff] [blame]178<div class="doc_subsection"> <a name="owners">Code Owners</a></div>
179<div class="doc_text">
180
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]181<p>The LLVM Project relies on two features of its process to maintain rapid
182 development in addition to the high quality of its source base: the
183 combination of code review plus post-commit review for trusted maintainers.
184 Having both is a great way for the project to take advantage of the fact that
185 most people do the right thing most of the time, and only commit patches
186 without pre-commit review when they are confident they are right.</p>
Chris Lattnere268a402007-12-03 19:00:47 +0000[diff] [blame]187
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]188<p>The trick to this is that the project has to guarantee that all patches that
189 are committed are reviewed after they go in: you don't want everyone to
190 assume someone else will review it, allowing the patch to go unreviewed. To
191 solve this problem, we have a notion of an 'owner' for a piece of the code.
192 The sole responsibility of a code owner is to ensure that a commit to their
193 area of the code is appropriately reviewed, either by themself or by someone
194 else. The current code owners are:</p>
Chris Lattnere268a402007-12-03 19:00:47 +0000[diff] [blame]195
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]196<ol>
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]197 <li><b>Evan Cheng</b>: Code generator and all targets.</li>
198
Chris Lattneraf5bd672009-09-16 05:36:07 +0000[diff] [blame]199 <li><b>Doug Gregor</b>: Clang Basic, Lex, Parse, and Sema Libraries.</li>
200
Chris Lattnerb2030432009-09-16 05:37:13 +0000[diff] [blame]201 <li><b>Anton Korobeynikov</b>: Exception handling, debug information, and
202 Windows codegen.</li>
203
Chris Lattnerf86a7782009-09-16 05:42:12 +0000[diff] [blame]204 <li><b>Ted Kremenek</b>: Clang Static Analyzer.</li>
205
Chris Lattner941f4cd2009-09-16 05:36:54 +0000[diff] [blame]206 <li><b>Chris Lattner</b>: Everything not covered by someone else.</li>
Chris Lattneraf5bd672009-09-16 05:36:07 +0000[diff] [blame]207
208 <li><b>Duncan Sands</b>: llvm-gcc 4.2.</li>
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]209</ol>
Chris Lattnere268a402007-12-03 19:00:47 +0000[diff] [blame]210
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]211<p>Note that code ownership is completely different than reviewers: anyone can
212 review a piece of code, and we welcome code review from anyone who is
213 interested. Code owners are the "last line of defense" to guarantee that all
214 patches that are committed are actually reviewed.</p>
Chris Lattnere268a402007-12-03 19:00:47 +0000[diff] [blame]215
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]216<p>Being a code owner is a somewhat unglamorous position, but it is incredibly
217 important for the ongoing success of the project. Because people get busy,
218 interests change, and unexpected things happen, code ownership is purely
219 opt-in, and anyone can choose to resign their "title" at any time. For now,
220 we do not have an official policy on how one gets elected to be a code
221 owner.</p>
Chris Lattnere268a402007-12-03 19:00:47 +0000[diff] [blame]222</div>
223
Chris Lattnere268a402007-12-03 19:00:47 +0000[diff] [blame]224<!-- _______________________________________________________________________ -->
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]225<div class="doc_subsection"> <a name="testcases">Test Cases</a></div>
226<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]227<p>Developers are required to create test cases for any bugs fixed and any new
228 features added. Some tips for getting your testcase approved:</p>
229
230<ol>
231 <li>All feature and regression test cases are added to the
232 <tt>llvm/test</tt> directory. The appropriate sub-directory should be
233 selected (see the <a href="TestingGuide.html">Testing Guide</a> for
234 details).</li>
235
236 <li>Test cases should be written in <a href="LangRef.html">LLVM assembly
237 language</a> unless the feature or regression being tested requires
238 another language (e.g. the bug being fixed or feature being implemented is
239 in the llvm-gcc C++ front-end, in which case it must be written in
240 C++).</li>
241
242 <li>Test cases, especially for regressions, should be reduced as much as
243 possible, by <a href="Bugpoint.html">bugpoint</a> or manually. It is
244 unacceptable to place an entire failing program into <tt>llvm/test</tt> as
245 this creates a <i>time-to-test</i> burden on all developers. Please keep
246 them short.</li>
247</ol>
Chris Lattner0cca50c2007-02-19 06:57:16 +0000[diff] [blame]248
Chris Lattnerb742ff02010-09-02 00:09:17 +0000[diff] [blame]249<p>Note that llvm/test and clang/test are designed for regression and small
250 feature tests only. More extensive test cases (e.g., entire applications,
251 benchmarks, etc)
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]252 should be added to the <tt>llvm-test</tt> test suite. The llvm-test suite is
253 for coverage (correctness, performance, etc) testing, not feature or
254 regression testing.</p>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]255</div>
256
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]257<!-- _______________________________________________________________________ -->
Chris Lattner39582bd2007-02-19 05:47:13 +0000[diff] [blame]258<div class="doc_subsection"> <a name="quality">Quality</a></div>
259<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]260<p>The minimum quality standards that any change must satisfy before being
261 committed to the main development branch are:</p>
262
263<ol>
264 <li>Code must adhere to the <a href="CodingStandards.html">LLVM Coding
265 Standards</a>.</li>
266
267 <li>Code must compile cleanly (no errors, no warnings) on at least one
268 platform.</li>
269
270 <li>Bug fixes and new features should <a href="#testcases">include a
271 testcase</a> so we know if the fix/feature ever regresses in the
272 future.</li>
273
Chris Lattnerb742ff02010-09-02 00:09:17 +0000[diff] [blame]274 <li>Code must pass the <tt>llvm/test</tt> test suite.</li>
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]275
276 <li>The code must not cause regressions on a reasonable subset of llvm-test,
277 where "reasonable" depends on the contributor's judgement and the scope of
278 the change (more invasive changes require more testing). A reasonable
279 subset might be something like
280 "<tt>llvm-test/MultiSource/Benchmarks</tt>".</li>
281</ol>
282
283<p>Additionally, the committer is responsible for addressing any problems found
284 in the future that the change is responsible for. For example:</p>
285
286<ul>
287 <li>The code should compile cleanly on all supported platforms.</li>
288
289 <li>The changes should not cause any correctness regressions in the
290 <tt>llvm-test</tt> suite and must not cause any major performance
291 regressions.</li>
292
293 <li>The change set should not cause performance or correctness regressions for
294 the LLVM tools.</li>
295
296 <li>The changes should not cause performance or correctness regressions in
297 code compiled by LLVM on all applicable targets.</li>
298
299 <li>You are expected to address any <a href="http://llvm.org/bugs/">bugzilla
300 bugs</a> that result from your change.</li>
301</ul>
Chris Lattner39582bd2007-02-19 05:47:13 +0000[diff] [blame]302
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]303<p>We prefer for this to be handled before submission but understand that it
Chris Lattnerd7f10d32009-08-01 19:25:25 +0000[diff] [blame]304 isn't possible to test all of this for every submission. Our build bots and
305 nightly testing infrastructure normally finds these problems. A good rule of
306 thumb is to check the nightly testers for regressions the day after your
307 change. Build bots will directly email you if a group of commits that
308 included yours caused a failure. You are expected to check the build bot
309 messages to see if they are your fault and, if so, fix the breakage.</p>
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]310
311<p>Commits that violate these quality standards (e.g. are very broken) may be
312 reverted. This is necessary when the change blocks other developers from
313 making progress. The developer is welcome to re-commit the change after the
314 problem has been fixed.</p>
Chris Lattner39582bd2007-02-19 05:47:13 +0000[diff] [blame]315</div>
316
317<!-- _______________________________________________________________________ -->
Chris Lattner1acdc952007-02-19 05:49:11 +0000[diff] [blame]318<div class="doc_subsection">
319 <a name="commitaccess">Obtaining Commit Access</a></div>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]320<div class="doc_text">
321
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]322<p>We grant commit access to contributors with a track record of submitting high
323 quality patches. If you would like commit access, please send an email to
324 <a href="mailto:sabre@nondot.org">Chris</a> with the following
325 information:</p>
Chris Lattnerbebcdabd82007-12-03 00:36:20 +0000[diff] [blame]326
327<ol>
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]328 <li>The user name you want to commit with, e.g. "hacker".</li>
329
Chris Lattnerbebcdabd82007-12-03 00:36:20 +0000[diff] [blame]330 <li>The full name and email address you want message to llvm-commits to come
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]331 from, e.g. "J. Random Hacker &lt;hacker@yoyodyne.com&gt;".</li>
332
Chris Lattnerbebcdabd82007-12-03 00:36:20 +0000[diff] [blame]333 <li>A "password hash" of the password you want to use, e.g. "2ACR96qjUqsyM".
334 Note that you don't ever tell us what your password is, you just give it
335 to us in an encrypted form. To get this, run "htpasswd" (a utility that
336 comes with apache) in crypt mode (often enabled with "-d"), or find a web
337 page that will do it for you.</li>
338</ol>
339
340<p>Once you've been granted commit access, you should be able to check out an
341 LLVM tree with an SVN URL of "https://username@llvm.org/..." instead of the
342 normal anonymous URL of "http://llvm.org/...". The first time you commit
343 you'll have to type in your password. Note that you may get a warning from
344 SVN about an untrusted key, you can ignore this. To verify that your commit
345 access works, please do a test commit (e.g. change a comment or add a blank
346 line). Your first commit to a repository may require the autogenerated email
347 to be approved by a mailing list. This is normal, and will be done when
348 the mailing list owner has time.</p>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]349
350<p>If you have recently been granted commit access, these policies apply:</p>
Chris Lattnerbebcdabd82007-12-03 00:36:20 +0000[diff] [blame]351
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]352<ol>
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]353 <li>You are granted <i>commit-after-approval</i> to all parts of LLVM. To get
354 approval, submit a <a href="#patches">patch</a> to
355 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>.
356 When approved you may commit it yourself.</li>
357
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]358 <li>You are allowed to commit patches without approval which you think are
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]359 obvious. This is clearly a subjective decision &mdash; we simply expect
360 you to use good judgement. Examples include: fixing build breakage,
361 reverting obviously broken patches, documentation/comment changes, any
362 other minor changes.</li>
363
364 <li>You are allowed to commit patches without approval to those portions of
365 LLVM that you have contributed or maintain (i.e., have been assigned
366 responsibility for), with the proviso that such commits must not break the
367 build. This is a "trust but verify" policy and commits of this nature are
368 reviewed after they are committed.</li>
369
370 <li>Multiple violations of these policies or a single egregious violation may
371 cause commit access to be revoked.</li>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]372</ol>
Chris Lattner0cca50c2007-02-19 06:57:16 +0000[diff] [blame]373
374<p>In any case, your changes are still subject to <a href="#reviews">code
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]375 review</a> (either before or after they are committed, depending on the
376 nature of the change). You are encouraged to review other peoples' patches
377 as well, but you aren't required to.</p>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]378</div>
379
380<!-- _______________________________________________________________________ -->
Chris Lattnerc7d954e2007-02-19 05:43:04 +0000[diff] [blame]381<div class="doc_subsection"> <a name="newwork">Making a Major Change</a></div>
382<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]383<p>When a developer begins a major new project with the aim of contributing it
384 back to LLVM, s/he should inform the community with an email to
385 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">llvmdev</a>
386 email list, to the extent possible. The reason for this is to:
387
388<ol>
389 <li>keep the community informed about future changes to LLVM, </li>
390
391 <li>avoid duplication of effort by preventing multiple parties working on the
392 same thing and not knowing about it, and</li>
393
394 <li>ensure that any technical issues around the proposed work are discussed
395 and resolved before any significant work is done.</li>
396</ol>
Chris Lattnerc7d954e2007-02-19 05:43:04 +0000[diff] [blame]397
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]398<p>The design of LLVM is carefully controlled to ensure that all the pieces fit
399 together well and are as consistent as possible. If you plan to make a major
400 change to the way LLVM works or want to add a major new extension, it is a
401 good idea to get consensus with the development community before you start
402 working on it.</p>
Chris Lattnerc7d954e2007-02-19 05:43:04 +0000[diff] [blame]403
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]404<p>Once the design of the new feature is finalized, the work itself should be
405 done as a series of <a href="#incremental">incremental changes</a>, not as a
406 long-term development branch.</p>
Chris Lattnerc7d954e2007-02-19 05:43:04 +0000[diff] [blame]407</div>
408
409<!-- _______________________________________________________________________ -->
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]410<div class="doc_subsection"> <a name="incremental">Incremental Development</a>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]411</div>
412<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]413<p>In the LLVM project, we do all significant changes as a series of incremental
414 patches. We have a strong dislike for huge changes or long-term development
415 branches. Long-term development branches have a number of drawbacks:</p>
416
417<ol>
418 <li>Branches must have mainline merged into them periodically. If the branch
419 development and mainline development occur in the same pieces of code,
420 resolving merge conflicts can take a lot of time.</li>
421
422 <li>Other people in the community tend to ignore work on branches.</li>
423
424 <li>Huge changes (produced when a branch is merged back onto mainline) are
425 extremely difficult to <a href="#reviews">code review</a>.</li>
426
427 <li>Branches are not routinely tested by our nightly tester
428 infrastructure.</li>
429
430 <li>Changes developed as monolithic large changes often don't work until the
431 entire set of changes is done. Breaking it down into a set of smaller
432 changes increases the odds that any of the work will be committed to the
433 main repository.</li>
434</ol>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]435
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]436<p>To address these problems, LLVM uses an incremental development style and we
437 require contributors to follow this practice when making a large/invasive
438 change. Some tips:</p>
439
440<ul>
441 <li>Large/invasive changes usually have a number of secondary changes that are
442 required before the big change can be made (e.g. API cleanup, etc). These
443 sorts of changes can often be done before the major change is done,
444 independently of that work.</li>
445
446 <li>The remaining inter-related work should be decomposed into unrelated sets
447 of changes if possible. Once this is done, define the first increment and
448 get consensus on what the end goal of the change is.</li>
449
450 <li>Each change in the set can be stand alone (e.g. to fix a bug), or part of
451 a planned series of changes that works towards the development goal.</li>
452
453 <li>Each change should be kept as small as possible. This simplifies your work
454 (into a logical progression), simplifies code review and reduces the
455 chance that you will get negative feedback on the change. Small increments
456 also facilitate the maintenance of a high quality code base.</li>
457
458 <li>Often, an independent precursor to a big change is to add a new API and
459 slowly migrate clients to use the new API. Each change to use the new API
460 is often "obvious" and can be committed without review. Once the new API
461 is in place and used, it is much easier to replace the underlying
462 implementation of the API. This implementation change is logically
463 separate from the API change.</li>
464</ul>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]465
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]466<p>If you are interested in making a large change, and this scares you, please
467 make sure to first <a href="#newwork">discuss the change/gather consensus</a>
468 then ask about the best way to go about making the change.</p>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]469</div>
470
471<!-- _______________________________________________________________________ -->
Chris Lattnerc7d954e2007-02-19 05:43:04 +0000[diff] [blame]472<div class="doc_subsection"><a name="attribution">Attribution of
473Changes</a></div>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]474<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]475<p>We believe in correct attribution of contributions to their contributors.
476 However, we do not want the source code to be littered with random
477 attributions "this code written by J. Random Hacker" (this is noisy and
478 distracting). In practice, the revision control system keeps a perfect
479 history of who changed what, and the CREDITS.txt file describes higher-level
480 contributions. If you commit a patch for someone else, please say "patch
481 contributed by J. Random Hacker!" in the commit message.</p>
Chris Lattnerab2b10c2007-12-29 19:56:08 +0000[diff] [blame]482
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]483<p>Overall, please do not add contributor names to the source code.</p>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]484</div>
485
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]486<!--=========================================================================-->
Chris Lattner793aa382007-02-19 06:19:16 +0000[diff] [blame]487<div class="doc_section">
488 <a name="clp">Copyright, License, and Patents</a>
489</div>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]490<!--=========================================================================-->
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]491
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]492<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]493<p>This section addresses the issues of copyright, license and patents for the
494 LLVM project. Currently, the University of Illinois is the LLVM copyright
495 holder and the terms of its license to LLVM users and developers is the
496 <a href="http://www.opensource.org/licenses/UoI-NCSA.php">University of
497 Illinois/NCSA Open Source License</a>.</p>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]498
499<div class="doc_notes">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]500<p style="text-align:center;font-weight:bold">NOTE: This section deals with
501 legal matters but does not provide legal advice. We are not lawyers, please
502 seek legal counsel from an attorney.</p>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]503</div>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]504</div>
505
506<!-- _______________________________________________________________________ -->
507<div class="doc_subsection"><a name="copyright">Copyright</a></div>
508<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]509<p>For consistency and ease of management, the project requires the copyright
510 for all LLVM software to be held by a single copyright holder: the University
511 of Illinois (UIUC).</p>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]512
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]513<p>Although UIUC may eventually reassign the copyright of the software to
514 another entity (e.g. a dedicated non-profit "LLVM Organization") the intent
515 for the project is to always have a single entity hold the copyrights to LLVM
516 at any given time.</p>
Chris Lattner305915b2008-05-20 20:06:53 +0000[diff] [blame]517
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]518<p>We believe that having a single copyright holder is in the best interests of
519 all developers and users as it greatly reduces the managerial burden for any
520 kind of administrative or technical decisions about LLVM. The goal of the
521 LLVM project is to always keep the code open and <a href="#license">licensed
522 under a very liberal license</a>.</p>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]523</div>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]524
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]525<!-- _______________________________________________________________________ -->
526<div class="doc_subsection"><a name="license">License</a></div>
527<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]528<p>We intend to keep LLVM perpetually open source and to use a liberal open
529 source license. The current license is the
530 <a href="http://www.opensource.org/licenses/UoI-NCSA.php">University of
Dan Gohman621a4152010-02-26 20:18:32 +0000[diff] [blame]531 Illinois/NCSA Open Source License</a>, which boils down to this:</p>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]532
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]533<ul>
534 <li>You can freely distribute LLVM.</li>
535
536 <li>You must retain the copyright notice if you redistribute LLVM.</li>
537
538 <li>Binaries derived from LLVM must reproduce the copyright notice (e.g. in
539 an included readme file).</li>
540
541 <li>You can't use our names to promote your LLVM derived products.</li>
542
543 <li>There's no warranty on LLVM at all.</li>
544</ul>
545
546<p>We believe this fosters the widest adoption of LLVM because it <b>allows
547 commercial products to be derived from LLVM</b> with few restrictions and
548 without a requirement for making any derived works also open source (i.e.
549 LLVM's license is not a "copyleft" license like the GPL). We suggest that you
550 read the <a href="http://www.opensource.org/licenses/UoI-NCSA.php">License</a>
551 if further clarification is needed.</p>
552
553<p>Note that the LLVM Project does distribute llvm-gcc, <b>which is GPL.</b>
554 This means that anything "linked" into llvm-gcc must itself be compatible
555 with the GPL, and must be releasable under the terms of the GPL. This
556 implies that <b>any code linked into llvm-gcc and distributed to others may
557 be subject to the viral aspects of the GPL</b> (for example, a proprietary
558 code generator linked into llvm-gcc must be made available under the GPL).
559 This is not a problem for code already distributed under a more liberal
560 license (like the UIUC license), and does not affect code generated by
561 llvm-gcc. It may be a problem if you intend to base commercial development
562 on llvm-gcc without redistributing your source code.</p>
563
564<p>We have no plans to change the license of LLVM. If you have questions or
565 comments about the license, please contact the
566 <a href="mailto:llvm-oversight@cs.uiuc.edu">LLVM Oversight Group</a>.</p>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]567</div>
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]568
569<!-- _______________________________________________________________________ -->
570<div class="doc_subsection"><a name="patents">Patents</a></div>
571<div class="doc_text">
Chris Lattnerb87fb2a2007-02-19 06:13:50 +0000[diff] [blame]572<p>To the best of our knowledge, LLVM does not infringe on any patents (we have
573 actually removed code from LLVM in the past that was found to infringe).
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]574 Having code in LLVM that infringes on patents would violate an important goal
575 of the project by making it hard or impossible to reuse the code for
Chris Lattnerd0742ce2007-02-19 06:15:33 +0000[diff] [blame]576 arbitrary purposes (including commercial use).</p>
Chris Lattnerb87fb2a2007-02-19 06:13:50 +0000[diff] [blame]577
578<p>When contributing code, we expect contributors to notify us of any potential
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]579 for patent-related trouble with their changes. If you or your employer own
580 the rights to a patent and would like to contribute code to LLVM that relies
581 on it, we require that the copyright owner sign an agreement that allows any
582 other user of LLVM to freely use your patent. Please contact
583 the <a href="mailto:llvm-oversight@cs.uiuc.edu">oversight group</a> for more
Chris Lattnerb87fb2a2007-02-19 06:13:50 +0000[diff] [blame]584 details.</p>
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]585</div>
586
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]587<!-- _______________________________________________________________________ -->
588<div class="doc_subsection"><a name="devagree">Developer Agreements</a></div>
589<div class="doc_text">
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]590<p>With regards to the LLVM copyright and licensing, developers agree to assign
591 their copyrights to UIUC for any contribution made so that the entire
592 software base can be managed by a single copyright holder. This implies that
593 any contributions can be licensed under the license that the project
594 uses.</p>
Chris Lattner64a4c112008-05-22 03:06:14 +0000[diff] [blame]595
Bill Wendling78c8fce2009-04-05 12:37:44 +0000[diff] [blame]596<p>When contributing code, you also affirm that you are legally entitled to
597 grant this copyright, personally or on behalf of your employer. If the code
598 belongs to some other entity, please raise this issue with the oversight
599 group before the code is committed.</p>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]600</div>
601
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]602<!-- *********************************************************************** -->
603<hr>
604<address>
605 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]606 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]607 <a href="http://validator.w3.org/check/referer"><img
Misha Brukmanf00ddb02008-12-11 18:23:24 +0000[diff] [blame]608 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
Chris Lattnerd0742ce2007-02-19 06:15:33 +0000[diff] [blame]609 Written by the
Reid Spencer3eedbd32007-02-14 07:57:48 +0000[diff] [blame]610 <a href="mailto:llvm-oversight@cs.uiuc.edu">LLVM Oversight Group</a><br>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]611 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
612 Last modified: $Date$
613</address>
614</body>
615</html>