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5 <title>LLVM Developer Policy</title>
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7</head>
8<body>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]9
10<div class="doc_title">LLVM Developer Policy</div>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]11<ol>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]12 <li><a href="#introduction">Introduction</a></li>
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]13 <li><a href="#policies">Developer Policies</a>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]14 <ol>
Chris Lattner1653fec2007-02-19 05:57:29 +0000[diff] [blame]15 <li><a href="#informed">Stay Informed</a></li>
16 <li><a href="#patches">Making a Patch</a></li>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]17 <li><a href="#reviews">Code Reviews</a></li>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]18 <li><a href="#testcases">Test Cases</a></li>
Chris Lattner1acdc952007-02-19 05:49:11 +0000[diff] [blame]19 <li><a href="#quality">Quality</a></li>
20 <li><a href="#commitaccess">Obtaining Commit Access</a></li>
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]21 <li><a href="#newwork">Making a Major Change</a></li>
22 <li><a href="#incremental">Incremental Development</a></li>
Chris Lattnerc7d954e2007-02-19 05:43:04 +0000[diff] [blame]23 <li><a href="#attribution">Attribution of Changes</a></li>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]24 </ol></li>
Chris Lattner793aa382007-02-19 06:19:16 +0000[diff] [blame^]25 <li><a href="#clp">Copyright, License, and Patents</a>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]26 <ol>
27 <li><a href="#copyright">Copyright</a></li>
28 <li><a href="#license">License</a></li>
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]29 <li><a href="#patents">Patents</a></li>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]30 <li><a href="#devagree">Developer Agreements</a></li>
31 </ol></li>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]32</ol>
33<div class="doc_author">Written by LLVM Oversight Team</div>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]34
35<!--=========================================================================-->
Reid Spencere7bd7d62007-02-14 17:24:04 +0000[diff] [blame]36<div class="doc_section"><a name="introduction">Introduction</a></div>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]37<!--=========================================================================-->
38<div class="doc_text">
39 <p>This document contains the LLVM Developer Policy which defines the
Reid Spencerbed92532007-02-13 17:04:09 +0000[diff] [blame]40 project's policy towards developers and their contributions. The intent of
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]41 this policy is to eliminate mis-communication, rework, and confusion that
42 might arise from the distributed nature of LLVM's development. By stating
43 the policy in clear terms, we hope each developer can know ahead of time
44 what to expect when making LLVM contributions.</p>
Reid Spencer5b9a6092007-02-14 22:55:40 +0000[diff] [blame]45 <p>This policy is also designed to accomplish the following objectives:</p>
46 <ol>
47 <li>Attract both users and developers to the LLVM project.</li>
48 <li>Make life as simple and easy for contributors as possible.</li>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]49 <li>Keep the top of tree CVS/SVN trees as stable as possible.</li>
Reid Spencer5b9a6092007-02-14 22:55:40 +0000[diff] [blame]50 </ol>
Chris Lattnerc7d954e2007-02-19 05:43:04 +0000[diff] [blame]51
52 <p>This policy is aimed at regular contributors to LLVM. People interested in
53 contributing one-off patches can do so in an informal way by sending them to
54 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">
55 llvm-commits mailing list</a> and engaging another developer to see it through
56 the process.</p>
57
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]58</div>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]59
60<!--=========================================================================-->
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]61<div class="doc_section"><a name="policies">Developer Policies</a></div>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]62<!--=========================================================================-->
63<div class="doc_text">
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]64 <p>This section contains policies that pertain generally to regular LLVM
65 developers. We always welcome <a href="#patches">random patches</a> from
66 people who do not routinely contribute to LLVM, but expect more from regular
67 contributors to keep the system as efficient as possible for everyone.
68 Regular LLVM developers are expected to meet the following obligations in
69 order for LLVM to maintain a high standard of quality.<p>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]70</div>
71
72<!-- _______________________________________________________________________ -->
73<div class="doc_subsection"> <a name="informed">Stay Informed</a> </div>
74<div class="doc_text">
75 <p>Developers should stay informed by reading at least the
Reid Spencer01f56be2007-02-14 16:21:10 +0000[diff] [blame]76 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">llvmdev</a>
77 email list. If you are doing anything more than just casual work on LLVM,
78 it is suggested that you also subscribe to the
79 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>
80 list and pay attention to changes being made by others.</p>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]81 <p>We recommend that active developers register an email account with
82 <a href="http://llvm.org/bugs/">LLVM Bugzilla</a> and preferably subscribe to
83 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmbugs">llvm-bugs</a>
84 email list to keep track of bugs and enhancements occurring in LLVM.</p>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]85</div>
86
87<!-- _______________________________________________________________________ -->
Chris Lattner1653fec2007-02-19 05:57:29 +0000[diff] [blame]88<div class="doc_subsection"> <a name="patches">Making a Patch</a></div>
89
90<div class="doc_text">
91
92<p>When making a patch for review, the goal is to make it as easy for the
93 reviewer to read it as possible. As such, we recommend that you:</p>
94 <ol>
95 <li>Make your patch against the CVS HEAD (main development trunk),
96 not a branch, and not an old version of LLVM. This makes it easy to
97 apply the patch.</li>
98
99 <li>Similarly, patches should be submitted soon after they are generated.
100 Old patches may not apply correctly if the underlying code changes between
101 the time the patch was created and the time it is applied.</li>
102
103 <li>Patches should be made with this command:
104 <pre>cvs diff -Ntdup -5</pre>
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]105 or with the utility <tt>utils/mkpatch</tt>, which makes it easy to read the
Chris Lattner1653fec2007-02-19 05:57:29 +0000[diff] [blame]106 diff.</li>
107
108 <li>Patches should not include differences in generated code such as the
109 code generated by <tt>flex</tt>, <tt>bison</tt> or <tt>tblgen</tt>. The
110 <tt>utils/mkpatch</tt> utility takes care of this for you.</li>
111
Chris Lattner1653fec2007-02-19 05:57:29 +0000[diff] [blame]112 </ol>
113</div>
114
115<!-- _______________________________________________________________________ -->
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]116<div class="doc_subsection"> <a name="reviews">Code Reviews</a></div>
117<div class="doc_text">
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]118 <p>LLVM has a code review policy. Code review is one way to increase the
119 quality of software. We generally follow these policies:</p>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]120 <ol>
Reid Spencer01f56be2007-02-14 16:21:10 +0000[diff] [blame]121 <li>All developers are required to have significant changes reviewed
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]122 before they are committed to the repository.</li>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]123 <li>Code reviews are conducted by email, usually on the llvm-commits
124 list.</li>
125 <li>Code can be reviewed either before it is committed or after. We expect
126 major changes to be reviewed before being committed, but smaller
127 changes (or changes where the developer owns the component) can be
128 reviewed after commit.</li>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]129 <li>The developer responsible for a code change is also responsible for
Chris Lattner1653fec2007-02-19 05:57:29 +0000[diff] [blame]130 making all necessary review-related changes.</li>
131 <li>Code review can be an iterative process, which goes until all the patch
132 is ready to be committed.</li>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]133 <li>Developers should participate in code reviews as both a reviewer and
134 a reviewee. We don't have a dedicated team of reviewers. If someone is
135 kind enough to review your code, you should return the favor for someone
136 else.</li>
137 </ol>
138</div>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]139
140<!-- _______________________________________________________________________ -->
141<div class="doc_subsection"> <a name="testcases">Test Cases</a></div>
142<div class="doc_text">
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]143 <p>Developers are required to create test cases for any bugs fixed and any new
144 features added. The following policies apply:</p>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]145 <ol>
146 <li>All feature and regression test cases must be added to the
Reid Spencer80483bb2007-02-13 09:20:14 +0000[diff] [blame]147 <tt>llvm/test</tt> directory. The appropriate sub-directory should be
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]148 selected (see the <a href="TestingGuide.html">Testing Guide</a> for
Reid Spencer40602962007-02-13 20:57:57 +0000[diff] [blame]149 details).</li>
Reid Spencer01f56be2007-02-14 16:21:10 +0000[diff] [blame]150 <li>Test cases should be written in
151 <a href="LangRef.html">LLVM assembly language</a> unless the
Reid Spencer3eedbd32007-02-14 07:57:48 +0000[diff] [blame]152 feature or regression being tested requires another language (e.g. the
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]153 bug being fixed or feature being implemented is in the llvm-gcc C++
Reid Spencer3eedbd32007-02-14 07:57:48 +0000[diff] [blame]154 front-end).</li>
Reid Spencer01f56be2007-02-14 16:21:10 +0000[diff] [blame]155 <li>Test cases, especially for regressions, should be reduced as much as
Reid Spencer3eedbd32007-02-14 07:57:48 +0000[diff] [blame]156 possible, by <a href="CommandGuide/html/bugpoint.html">bugpoint</a> or
157 manually. It is unacceptable
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]158 to place an entire failing program into <tt>llvm/test</tt> as this creates
Reid Spencer01f56be2007-02-14 16:21:10 +0000[diff] [blame]159 a <i>time-to-test</i> burden on all developers. Please keep them short.</li>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]160 <li>More extensive test cases (applications, benchmarks, etc.) should be
Reid Spencer3eedbd32007-02-14 07:57:48 +0000[diff] [blame]161 added to the <tt>llvm-test</tt> test suite. This test suite is for
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]162 coverage: not features or regressions.</li>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]163 </ol>
164</div>
165
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]166<!-- _______________________________________________________________________ -->
Chris Lattner39582bd2007-02-19 05:47:13 +0000[diff] [blame]167<div class="doc_subsection"> <a name="quality">Quality</a></div>
168<div class="doc_text">
169 <p>The minimum quality standards that any change must satisfy before being
170 committed to the main development branch are:</p>
171 <ol>
172 <li>Code must adhere to the
173 <a href="CodingStandards.html">LLVM Coding Standards</a>.</li>
174 <li>Code must compile cleanly (no errors, no warnings) on at least one
175 platform.</li>
176 <li>Bug fixes and new features should <a href="#testcases">include a
177 testcase</a> so we know if the fix/feature ever regresses in the
178 future.</li>
179 <li>Code must pass the dejagnu (llvm/test) test suite.</li>
180 <li>The code must not cause regressions on a reasonable subset of llvm-test,
181 where "reasonable" depends on the contributor's judgement and the scope
182 of the change (more invasive changes require more testing). A reasonable
183 subset is "<tt>llvm-test/MultiSource/Benchmarks</tt>".</li>
184 </ol>
185 <p>Additionally, the committer is responsible for addressing any problems
186 found in the future that the change is responsible for. For example:</p>
187 <ul>
188 <li>The code should compile cleanly on all platforms.</li>
189 <li>The changes should not cause regressions in the <tt>llvm-test</tt>
190 suite including SPEC CINT2000, SPEC CFP2000, SPEC CINT2006, and
191 SPEC CFP2006.</li>
192 <li>The change set should not cause performance or correctness regressions
193 for the LLVM tools.</li>
194 <li>The changes should not cause performance or correctness regressions in
195 code compiled by LLVM on all applicable targets.</li>
196 <li>You are expected to address any <a href="http://llvm.org/bugs/">bugzilla
197 bugs</a> that result from your change.</li>
198 </ul>
199
200 <p>We prefer for this to be handled before submission but understand that it's
201 not possible to test all of this for every submission. Our nightly testing
202 infrastructure normally finds these problems. A good rule of thumb is to
203 check the nightly testers for regressions the day after your change.</p>
204
205 <p>Commits that violate these quality standards (e.g. are very broken) may
206 be reverted. This is necessary when the change blocks other developers from
207 making progress. The developer is welcome to re-commit the change after
208 the problem has been fixed.</p>
209</div>
210
211<!-- _______________________________________________________________________ -->
Chris Lattner1acdc952007-02-19 05:49:11 +0000[diff] [blame]212<div class="doc_subsection">
213 <a name="commitaccess">Obtaining Commit Access</a></div>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]214<div class="doc_text">
215
216<p>
217We grant commit access to contributors with a track record of submitting high
218quality patches. If you would like commit access, please send an email to the
219<a href="mailto:llvm-oversight@cs.uiuc.edu">LLVM oversight group</a>.</p>
220
221<p>If you have recently been granted commit access, these policies apply:</p>
222<ol>
223 <li>You are granted <i>commit-after-approval</i> to all parts of LLVM.
224 To get approval, submit a <a href="#patches">patch</a> to
225 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">
226 llvm-commits</a>. When approved you may commit it yourself.</li>
227 <li>You are allowed to commit patches without approval which you think are
228 obvious. This is clearly a subjective decision. We simply expect you to
229 use good judgement. Examples include: fixing build breakage, reverting
230 obviously broken patches, documentation/comment changes, any other minor
231 changes.</li>
232 <li>You are allowed to commit patches without approval to those portions
233 of LLVM that you have contributed or maintain (have been assigned
234 responsibility for), with the proviso that such commits must not break the
235 build. This is a "trust but verify" policy and commits of this nature are
236 reviewed after they are committed.</li>
237 <li>Multiple violations of these policies or a single egregious violation
238 may cause commit access to be revoked.</li>
239</ol>
240
241</div>
242
243<!-- _______________________________________________________________________ -->
Chris Lattnerc7d954e2007-02-19 05:43:04 +0000[diff] [blame]244<div class="doc_subsection"> <a name="newwork">Making a Major Change</a></div>
245<div class="doc_text">
246 <p>When a developer begins a major new project with the aim of contributing
247 it back to LLVM, s/he should inform the community with an email to
248 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">llvm-dev</a>
249 email list, to the extent possible. The reason for this is to:
250 <ol>
251 <li>keep the community informed about future changes to LLVM, </li>
252 <li>avoid duplication of effort by having multiple parties working on the
253 same thing and not knowing about it, and</li>
254 <li>ensure that any technical issues around the proposed work are
255 discussed and resolved before any significant work is done.</li>
256 </ol>
257
258 <p>The design of LLVM is carefully controlled to ensure that all the pieces
259 fit together well and are as consistent as possible. If you plan to make a
260 major change to the way LLVM works or
261 a major new extension, it is a good idea to get consensus with the development
262 community before you start working on it.</p>
263
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]264 <p>Once the design of the new feature is finalized, the work itself should be
265 done as a series of <a href="#incremental">incremental changes</a>, not as
266 a long-term development branch.</p>
267
Chris Lattnerc7d954e2007-02-19 05:43:04 +0000[diff] [blame]268</div>
269
270<!-- _______________________________________________________________________ -->
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]271<div class="doc_subsection"> <a name="incremental">Incremental Development</a>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]272</div>
273<div class="doc_text">
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]274 <p>In the LLVM project, we do all significant changes as a series of
275 incremental patches. We have a strong dislike for huge changes or
276 long-term development branches. Long-term development branches have a
277 number of drawbacks:</p>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]278
279 <ol>
280 <li>Branches must have mainline merged into them periodically. If the branch
281 development and mainline development occur in the same pieces of code,
282 resolving merge conflicts can take a lot of time.</li>
283 <li>Other people in the community tend to ignore work on branches.</li>
284 <li>Huge changes (produced when a branch is merged back onto mainline) are
285 extremely difficult to <a href="#reviews">code review</a>.</li>
286 <li>Branches are not routinely tested by our nightly tester
287 infrastructure.</li>
288 <li>Changes developed as monolithic large changes often don't work until the
289 entire set of changes is done. Breaking it down into a set of smaller
290 changes increases the odds that any of the work will be committed to the
291 main repository.</li>
292 </ol>
293
294 <p>
295 To address these problems, LLVM uses an incremental development style and we
296 require contributors to follow this practice when making a large/invasive
297 change. Some tips:</p>
298
299 <ul>
300 <li>Large/invasive changes usually have a number of secondary changes that
301 are required before the big change can be made (e.g. API cleanup, etc).
302 These sorts of changes can often be done before the major change is done,
303 independently of that work.</li>
304 <li>The remaining inter-related work should be decomposed into unrelated
305 sets of changes if possible. Once this is done, define the first increment
306 and get consensus on what the end goal of the change is.</li>
Chris Lattner8bb16ff2007-02-19 05:59:30 +0000[diff] [blame]307
308 <li>Each change in the set can be stand alone (e.g. to fix a bug), or part
309 of a planned series of changes that works towards the development goal.</li>
310
311 <li>Each change should be kept as small as possible. This simplifies your
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]312 work (into a logical progression), simplifies code review and reduces the
313 chance that you will get negative feedback on the change. Small increments
314 also facilitate the maintenance of a high quality code base.</li>
Chris Lattner8bb16ff2007-02-19 05:59:30 +0000[diff] [blame]315
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]316 <li>Often, an independent precursor to a big change is to add a new API and
317 slowly migrate clients to use the new API. Each change to use the new
318 API is often "obvious" and can be committed without review. Once the
319 new API is in place and used, it is often easy to replace the underlying
320 implementation of the API.</li>
321 </ul>
322
323 <p>If you are interested in making a large change, and this scares you, please
324 make sure to first <a href="#newwork">discuss the change/gather
325 consensus</a> then feel free to ask about the best way to go about making
326 the change.</p>
327</div>
328
329<!-- _______________________________________________________________________ -->
Chris Lattnerc7d954e2007-02-19 05:43:04 +0000[diff] [blame]330<div class="doc_subsection"><a name="attribution">Attribution of
331Changes</a></div>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]332<div class="doc_text">
333 <p>We believe in correct attribution of contributions to
334 their contributors. However, we do not want the source code to be littered
335 with random attributions (this is noisy/distracting and revision control
336 keeps a perfect history of this anyway). As such, we follow these rules:</p>
337 <ol>
338 <li>Developers who originate new files in LLVM should place their name at
339 the top of the file per the
340 <a href="CodingStandards.html#scf_commenting">Coding Standards</a>.</li>
341 <li>There should be only one name at the top of the file and it should be
342 the person who created the file.</li>
343 <li>Placing your name in the file does not imply <a
Chris Lattner793aa382007-02-19 06:19:16 +0000[diff] [blame^]344 href="#clp">copyright</a>: it is only used to attribute the file to
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]345 its original author.</li>
346 <li>Developers should be aware that after some time has passed, the name at
347 the top of a file may become meaningless as maintenance/ownership of files
348 changes. Revision control keeps an accurate history of contributions.</li>
349 <li>Developers should maintain their entry in the
350 <a href="http://llvm.org/cvsweb/cvsweb.cgi/llvm/CREDITS.TXT?rev=HEAD&amp;content-type=text/x-cvsweb-markup">CREDITS.txt</a>
351 file to summarize their contributions.</li>
352 <li>Commit comments should contain correct attribution of the person who
353 submitted the patch if that person is not the committer (i.e. when a
354 developer with commit privileges commits a patch for someone else).</li>
355 </ol>
356</div>
357
358
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]359
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]360<!--=========================================================================-->
Chris Lattner793aa382007-02-19 06:19:16 +0000[diff] [blame^]361<div class="doc_section">
362 <a name="clp">Copyright, License, and Patents</a>
363</div>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]364<!--=========================================================================-->
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]365
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]366<div class="doc_text">
367 <p>We address here the issues of copyright and license for the LLVM project.
Reid Spencer01f56be2007-02-14 16:21:10 +0000[diff] [blame]368 The object of the copyright and license is the LLVM source code and
369 documentation.
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]370 Currently, the University of Illinois is the LLVM copyright holder and the
371 terms of its license to LLVM users and developers is the
372 <a href="http://www.opensource.org/licenses/UoI-NCSA.php">University of
373 Illinois/NCSA Open Source License</a>.
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]374
375<div class="doc_notes">
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]376 <p><b>NOTE: This section deals with legal matters but does not provide
377 official legal advice. We are not lawyers, please seek legal counsel from an
378 attorney.</b></p>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]379</div>
380
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]381</div>
382
383<!-- _______________________________________________________________________ -->
384<div class="doc_subsection"><a name="copyright">Copyright</a></div>
385<div class="doc_text">
386 <p>
Reid Spencer01f56be2007-02-14 16:21:10 +0000[diff] [blame]387 <p>For consistency and ease of management, the project requires the
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]388 copyright for all LLVM software to be held by a single copyright holder:
389 the University of Illinois (UIUC).</p>
390
391 <p>
392 Although UIUC may eventually reassign the copyright of the software to another
393 entity (e.g. a dedicated non-profit "LLVM Organization", or something)
394 the intent for the project is to always have a single entity hold the
395 copyrights to LLVM at any given time.</p>
396
397 <p>We believe that having a single copyright
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]398 holder is in the best interests of all developers and users as it greatly
399 reduces the managerial burden for any kind of administrative or technical
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]400 decisions about LLVM. The goal of the LLVM project is to always keep the code
401 open and <a href="#license">licensed under a very liberal license</a>.</p>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]402</div>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]403
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]404<!-- _______________________________________________________________________ -->
405<div class="doc_subsection"><a name="license">License</a></div>
406<div class="doc_text">
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]407 <p>We intend to keep LLVM perpetually open source
408 and to use a liberal open source license. The current license is the
Reid Spencer01f56be2007-02-14 16:21:10 +0000[diff] [blame]409 <a href="http://www.opensource.org/licenses/UoI-NCSA.php">
410 University of Illinois/NCSA Open Source License</a>, which boils
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]411 down to this:</p>
412 <ul>
413 <li>You can freely distribute LLVM.</li>
414 <li>You must retain the copyright notice if you redistribute LLVM.</li>
415 <li>Binaries derived from LLVM must reproduce the copyright notice.</li>
416 <li>You can't use our names to promote your LLVM derived products.</li>
417 <li>There's no warranty on LLVM at all.</li>
418 </ul>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]419
420 <p>We believe this fosters the widest adoption of LLVM because it <b>allows
421 commercial products to be derived from LLVM</b> with few restrictions and
Reid Spencer5b9a6092007-02-14 22:55:40 +0000[diff] [blame]422 without a requirement for making any derived works also open source (i.e.
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]423 LLVM's license is not a "copyleft" license like the GPL). We suggest that you
424 read the <a href="http://www.opensource.org/licenses/UoI-NCSA.php">License</a>
Reid Spencer853418d2007-02-14 22:58:39 +0000[diff] [blame]425 if further clarification is needed.</p>
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]426
427 <p>Note that the LLVM Project does distribute some code that includes GPL
428 software (notably, llvm-gcc which is based on the GCC GPL source base).
429 This means that anything "linked" into to llvm-gcc must itself be compatible
430 with the GPL, and must be releasable under the terms of the GPL. This implies
431 that you <b>any code linked into llvm-gcc and distributed may be subject to
432 the viral aspects of the GPL</b>. This is not a problem for the main LLVM
433 distribution (which is already licensed under a more liberal license), but may
434 be a problem if you intend to do commercial development without redistributing
435 your source code.</p>
436
437 <p>We have no plans to change the license of LLVM. If you have questions
438 or comments about the license, please contact the <a
439 href="mailto:llvm-oversight@cs.uiuc.edu">LLVM Oversight Group</a>.</p>
440
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]441</div>
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]442
443<!-- _______________________________________________________________________ -->
444<div class="doc_subsection"><a name="patents">Patents</a></div>
445<div class="doc_text">
446
Chris Lattnerb87fb2a2007-02-19 06:13:50 +0000[diff] [blame]447<p>To the best of our knowledge, LLVM does not infringe on any patents (we have
448 actually removed code from LLVM in the past that was found to infringe).
Chris Lattnerd0742ce2007-02-19 06:15:33 +0000[diff] [blame]449 Having code in LLVM that infringes on patents would violate an important
450 goal of the project by making it hard or impossible to reuse the code for
451 arbitrary purposes (including commercial use).</p>
Chris Lattnerb87fb2a2007-02-19 06:13:50 +0000[diff] [blame]452
453<p>When contributing code, we expect contributors to notify us of any potential
454 for patent-related trouble with their changes. If you own the rights to a
455 patent and would like to contribute code to LLVM that relies on it, we
456 require that you sign an agreement that allows any other user of LLVM to
457 freely use your patent. Please contact the <a
458 href="mailto:llvm-oversight@cs.uiuc.edu">oversight group</a> for more
459 details.</p>
Chris Lattner1ff20cd2007-02-19 06:05:58 +0000[diff] [blame]460</div>
461
462
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]463<!-- _______________________________________________________________________ -->
464<div class="doc_subsection"><a name="devagree">Developer Agreements</a></div>
465<div class="doc_text">
Chris Lattner450f40a2007-02-19 03:50:31 +0000[diff] [blame]466 <p>With regards to the LLVM copyright and licensing, developers agree to
467 assign their copyrights to UIUC for any contribution made so that
468 the entire software base can be managed by a single copyright holder. This
469 implies that any contributions can be licensed under the license that the
Chris Lattner1acdc952007-02-19 05:49:11 +0000[diff] [blame]470 project uses.</p>
Reid Spencer78bade22007-02-14 07:22:19 +0000[diff] [blame]471</div>
472
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]473<!-- *********************************************************************** -->
474<hr>
475<address>
476 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
477 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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Chris Lattnerd0742ce2007-02-19 06:15:33 +0000[diff] [blame]480 Written by the
Reid Spencer3eedbd32007-02-14 07:57:48 +0000[diff] [blame]481 <a href="mailto:llvm-oversight@cs.uiuc.edu">LLVM Oversight Group</a><br>
Reid Spencer8d0ac692007-02-13 09:06:01 +0000[diff] [blame]482 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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