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5 <title>LLVM Developer Policy</title>
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9 <div class="doc_warning">DRAFT Only. DRAFT Only. DRAFT Only. DRAFT Only.</div>
11 <div class="doc_title">LLVM Developer Policy</div>
12 <table class="layout"><tr class="layout"><td class="layout">
15 <li><a href="#introduction">Introduction</a></li>
16 <li><a href="#general">General Policies</a>
18 <li><a href="#informed">Stay Informed</a> </li>
19 <li><a href="#newwork">Starting New Work</a></li>
20 <li><a href="#reviews">Code Reviews</a></li>
21 <li><a href="#incremental">Incremental Development</a></li>
22 <li><a href="#quality">Quality</a></li>
23 <li><a href="#testcases">Test Cases</a></li>
25 <li><a href="#patches">Patch Policies</a>
27 <li><a href="#p_form">Patch Form</a></li>
28 <li><a href="#p_testing">Patch Testing</a></li>
29 <li><a href="#p_submission">Patch Submission</a></li>
30 <li><a href="#p_aftersub">After Submission</a></li>
31 <li><a href="#p_aftercommit">After Commit</a></li>
32 <li><a href="#c_access">Obtaining Commit Access</a></li>
33 <li><a href="#c_new">New Committers</a></li>
35 <li><a href="#candl">Copyright and License</a>
37 <li><a href="#attribution">Attribution</a></li>
38 <li><a href="#copyright">Copyright</a></li>
39 <li><a href="#license">License</a></li>
40 <li><a href="#devagree">Developer Agreements</a></li>
42 <li><a href="#terms">Terminology</a></li>
43 <li><a href="#polnotes">Policy Notes</a></li>
45 <div class="doc_author">Written by LLVM Oversight Team</div>
46 </td><td class="layout">
48 <!--=========================================================================-->
49 <div class="doc_section"><a name="introduction">Introduction</a></div>
50 <!--=========================================================================-->
51 <div class="doc_text">
52 <p>This document contains the LLVM Developer Policy which defines the
53 project's policy towards developers and their contributions. The intent of
54 this policy is to eliminate mis-communication, rework, and confusion that
55 might arise from the distributed nature of LLVM's development. By stating
56 the policy in clear terms, we hope each developer can know ahead of time
57 what to expect when making LLVM contributions.</p>
58 <p>This policy is also designed to accomplish the following objectives:</p>
60 <li>Attract both users and developers to the LLVM project.</li>
61 <li>Make life as simple and easy for contributors as possible.</li>
62 <li>Indicate that LLVM is a mature project with a thriving community and
63 sensible policies directing its ongoing development.</li>
67 <!--=========================================================================-->
68 <div class="doc_section"><a name="general">General Policies</a></div>
69 <!--=========================================================================-->
70 <div class="doc_text">
71 <p>This section contains policies that pertain generally to LLVM developers.
72 LLVM Developers are expected to meet the following obligations in order
73 for LLVM to maintain a high standard of quality.<p>
76 <!-- _______________________________________________________________________ -->
77 <div class="doc_subsection"> <a name="informed">Stay Informed</a> </div>
78 <div class="doc_text">
79 <p>Developers should stay informed by reading at least the
80 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">llvmdev</a>
81 email list. If you are doing anything more than just casual work on LLVM,
82 it is suggested that you also subscribe to the
83 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>
84 list and pay attention to changes being made by others.</p>
85 <p>We recommend that active developers register an email account with
86 <a href="http://llvm.org/bugs/">LLVM Bugzilla</a> and preferably subscribe to
87 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmbugs">llvm-bugs</a>
88 email list to keep track of bugs and enhancements occurring in LLVM.</p>
91 <!-- _______________________________________________________________________ -->
92 <div class="doc_subsection"> <a name="newwork">Starting New Work</a></div>
93 <div class="doc_text">
94 <p>When a developer begins a major new project with the aim of contributing
95 it back to LLVM, s/he should inform the community with an email to
96 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">llvm-dev</a>
97 email list, to the extent possible. The reason for this is to:
99 <li>keep the community informed about future changes to LLVM, </li>
100 <li>avoid duplication of effort by having multiple parties working on the
101 same thing and not knowing about it, and</li>
102 <li>ensure that any technical issues around the proposed work are
103 discussed and resolved before any significant work is done.</li>
105 <p>The design of LLVM is carefully controlled to ensure that all the pieces
106 fit together well. If you plan to make a major change to the way LLVM works or
107 a major new extension, it is a good idea to get consensus with the development
108 community before you start working on it.</p>
112 <!-- _______________________________________________________________________ -->
113 <div class="doc_subsection"> <a name="reviews">Code Reviews</a></div>
114 <div class="doc_text">
115 <p>LLVM has a code review policy. Code review is an excellent way to ensure
116 high quality in the software. The following policies apply:</p>
118 <li>All developers are required to have significant changes reviewed
119 before they are committed to the repository.</li>
120 <li>Code reviews are conducted by email.</li>
121 <li>Code can be reviewed either before it is committed or after.</li>
122 <li>The developer responsible for a code change is also responsible for
123 making all necessary review changes.</li>
124 <li>Developers should participate in code reviews as both a reviewer and
125 a reviewee. We don't have a dedicated team of reviewers. If someone is
126 kind enough to review your code, you should return the favor for someone
131 <!-- _______________________________________________________________________ -->
132 <div class="doc_subsection"> <a name="incremental">Incremental Development</a>
134 <div class="doc_text">
135 <p>LLVM uses an incremental development style and all developers are expected
136 to follow this practice. Incremental development is a big key to LLVM's
137 success and it is essential that developers submit incremental patches. The
138 following defines the incremental development approach:</p>
140 <li>The first task is to define the increment and get consensus (with the
141 LLVM development community) on what the end goal of the change is. Making
142 random small changes that go nowhere is not useful for anyone.</li>
143 <li>An increment is the smallest patch size necessary to effect one change
145 <li>Increments can be stand alone (e.g. to fix a bug), or part of a planned
146 series of increments towards some development goal.</li>
147 <li>Increments should be kept as small as possible. This simplifies your
148 work (into a logical progression), simplifies code review and reduces the
149 chance that you will get negative feedback on the change. Small increments
150 also facilitate the maintenance of a high quality code base.</li>
151 <li>Larger increments require a larger testing effort.</li>
155 <!-- _______________________________________________________________________ -->
156 <div class="doc_subsection"> <a name="quality">Quality</a></div>
157 <div class="doc_text">
158 <p>The minimum quality standards for any change to the main development
161 <li>Code must adhere to the
162 <a href="CodingStandards.html">LLVM Coding Standards</a>.</li>
163 <li>Code must compile cleanly (no errors, no warnings) on at least one
165 <li>Code must pass the deja gnu (llvm/test) test suite.</li>
167 <p>Additionally, the committer is responsible for addressing all of the
168 following items (preferably before submission):</p>
170 <li>The code should compile cleanly on all platforms.</li>
171 <li>The changes should not cause regressions in the <tt>llvm-test</tt>
172 suite including SPEC CINT2000, SPEC CFP2000, SPEC CINT2006, and
174 <li>The change set should not cause performance or correctness regressions
175 for the LLVM tools.</li>
176 <li>The changes should not cause performance or correctness regressions in
177 code compiled by LLVM on all applicable targets.</li>
181 <!-- _______________________________________________________________________ -->
182 <div class="doc_subsection"> <a name="testcases">Test Cases</a></div>
183 <div class="doc_text">
184 <p>Developers are required to create test cases for regressions and new
185 features and include them with their changes. The following policies
188 <li>All feature and regression test cases must be added to the
189 <tt>llvm/test</tt> directory. The appropriate sub-directory should be
190 selected (see the <a href="TestingGuide.html">Testing Guide</a> for
192 <li>Test cases should be written in
193 <a href="LangRef.html">LLVM assembly language</a> unless the
194 feature or regression being tested requires another language (e.g. the
195 bug being fixed or feature being implemented is in the lvm-gcc C++
197 <li>Test cases, especially for regressions, should be reduced as much as
198 possible, by <a href="CommandGuide/html/bugpoint.html">bugpoint</a> or
199 manually. It is unacceptable
200 to place an entire failing program into <tt>llvm/test</tt> as this creates
201 a <i>time-to-test</i> burden on all developers. Please keep them short.</li>
202 <li>More extensive test cases (applications, benchmarks, etc.) should be
203 added to the <tt>llvm-test</tt> test suite. This test suite is for
204 coverage not features or regressions.</li>
208 <!--=========================================================================-->
209 <div class="doc_section"><a name="patches">Patch Policies</a></div>
210 <!--=========================================================================-->
211 <div class="doc_text">
212 <p>This section contains policies that pertain to submitting patches
213 to LLVM and committing code to the repository</p>
215 <!-- _______________________________________________________________________ -->
216 <div class="doc_subsection"> <a name="p_form">Patch Form</a></div>
217 <div class="doc_text">
218 <p>When submitting a patch, developers must follow these rules:</p>
220 <li>Patches must be made against the CVS HEAD (main development trunk),
222 <li>Patches should be made with this command:<pre>
223 cvs diff -Ntdup -5</pre> or with the utility <tt>utils/mkpatch</tt>.</li>
224 <li>Patches should not include differences in generated code such as the
225 code generated by <tt>flex</tt>, <tt>bison</tt> or <tt>tblgen</tt>. The
226 <tt>utils/mkpatch</tt> utility takes care of this for you.</li>
227 <li>Patches must not include any patent violations. To the best of our
228 knowledge, LLVM is free of any existing patent violations and it is our
229 intent to keep it that way. </li>
232 <!-- _______________________________________________________________________ -->
233 <div class="doc_subsection"> <a name="p_testing">Patch Testing</a></div>
234 <div class="doc_text">
235 <p>Before a patch is submitted for review, it should be tested to ensure
238 <li>The patch must compile against the CVS HEAD cleanly (zero warnings, zero
240 <li>All the llvm/test (Deja Gnu) tests must pass.</li>
241 <li>The patch should cause no regressions in the llvm-test test suite. How
242 much testing is appropriate depends on the nature of the patch. We leave it
243 to your good judgement, but you will be responsible for fixing any
244 regressions or reverting the patch.</li>
247 <!-- _______________________________________________________________________ -->
248 <div class="doc_subsection"> <a name="p_submission">Patch Submission</a></div>
249 <div class="doc_text">
250 <p>When a patch is ready to be submitted, these policies apply:</p>
252 <li>Patches should be submitted immediately after they are generated. Stale
253 patches may not apply correctly if the underlying code changes between the
254 time the patch was created and the time it is applied.</li>
255 <li>Patches should be submitted by e-mail to the
256 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">
257 llvm-commits</a> list.</li>
261 <!-- _______________________________________________________________________ -->
262 <div class="doc_subsection"> <a name="p_aftersub">After Submission</a></div>
263 <div class="doc_text">
264 <p>After a patch has been submitted, these policies apply:</p>
266 <li>The patch is subject to review by anyone on the
267 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>
269 <li>Changes recommended by a reviewer should be incorporated into your
270 patch or you should explain why the reviewer is incorrect.
271 <li>Changes to the patch must be re-submitted to the
272 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>
274 <li>This process iterates until all review issues have been addressed.</li>
278 <!-- _______________________________________________________________________ -->
279 <div class="doc_subsection"> <a name="p_aftercommit">After Commit</a></div>
280 <div class="doc_text">
281 <p>After a patch has been committed, these policies apply:</p>
283 <li>The patch is subject to further review by anyone on the llvm-commits
285 <li>The patch submitter is responsible for all aspects of the patch per
286 the <a href="quality">quality policy</a> above.</li>
287 <li>If the patch is discovered to not meet the
288 <a href="quality">quality policy</a> standards within a reasonable time
289 frame (24 hours), it may be subject to reversal.</li>
293 <!-- _______________________________________________________________________ -->
294 <div class="doc_subsection"> <a name="c_access">Obtaining Commit Access</a></div>
295 <div class="doc_text">
296 <p>Commit access to the repository is granted according to this policy:</p>
298 <li>Commit access is not granted to anyone unless they specifically ask for
300 <li>Requests for commit access must be sent to the
301 <a href="mailto:llvm-oversight@cs.uiuc.edu">LLVM Oversight Group</a>.</li>
302 <li>Granting commit access is at the sole discretion of the LLVM Oversight
305 <p>Submitting patches to LLVM via the patch policy above will greatly
306 increase the chance that your request for commit access is granted. Getting
307 to know the members of the LLVM community (email, IRC, in person contact,
308 etc.) will also increase your chances.</p>
311 <!-- _______________________________________________________________________ -->
312 <div class="doc_subsection"> <a name="c_new">New Committers</a></div>
313 <div class="doc_text">
314 <p>For those who have recently obtained commit access, the following policies
317 <li>You are granted <i>commit-after-approval</i> to all parts of LLVM.
318 To get approval, submit a patch to
319 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>
320 per the <a href="#patches">patch policies</a> above. When approved you
321 may commit it yourself.</li>
322 <li>You are allowed to commit patches without approval which you think are
323 obvious. This is clearly a subjective decision. We simply expect you to
324 use good judgement.</li>
325 <li>You are allowed to commit patches without approval to those portions
326 of LLVM that you own (contributed) or maintain (have been assigned
327 responsibility for), with the proviso that such commits must not break the
328 build. This is a "trust but verify" policy and commits of this nature are
329 reviewed after they are committed.</li>
330 <li>Commits that violate the <a href="quality">quality standards</a> may
331 be reverted. This is necessary when the change blocks other developers from
332 making progress. The developer is welcome to re-commit the change after
333 the problem has been fixed.</li>
334 <li>Multiple violations of these policies or a single egregious violation
335 may cause commit access to be revoked.</li>
339 <!--=========================================================================-->
340 <div class="doc_section"><a name="candl">Copyright and License</a></div>
341 <!--=========================================================================-->
342 <div class="doc_text">
343 <p>We address here the issues of copyright and license for the LLVM project.
344 The object of the copyright and license is the LLVM source code and
346 Currently, the University of Illinois is the LLVM copyright holder and the
347 terms of its license to LLVM users and developers is the
348 <a href="http://www.opensource.org/licenses/UoI-NCSA.php">University of
349 Illinois/NCSA Open Source License</a>.
352 <div class="doc_notes">
353 <p>NOTE: This section deals with legal matters but does not provide legal
354 advice. It is intended only as a general guideline.</p>
357 <!-- _______________________________________________________________________ -->
358 <div class="doc_subsection"><a name="attribution">Attribution</a></div>
359 <div class="doc_text">
360 <p>The LLVM project believes in correct attribution of contributions to
361 their contributors, as follows:</p>
363 <li>Developers who originate new files in LLVM should place their name at
364 the top of the file per the
365 <a href="CodingStandards.html">Coding Standards</a>.</li>
366 <li>There should be only one name at the top of the file and it should be
367 the person who created the file.</li>
368 <li>Placing your name in the file does not imply copyright but does
369 correctly attribute the file to its author.</li>
370 <li>Developers should be aware that after some time has passed, the name at
371 the top of a file may become meaningless as maintenance/ownership of files
373 <li>Developers should submit or commit patches to the
374 <a href="http://llvm.org/cvsweb/cvsweb.cgi/llvm/CREDITS.TXT?rev=1.67&content-type=text/x-cvsweb-markup">CREDITS.txt</a>
375 file to summarize their contributions.</li>
376 <li>Commit comments should contain correct attribution of the person who
377 submitted the patch if that person is not the committer (i.e. when a
378 developer with commit privileges commits a patch for someone else).</li>
382 <!-- _______________________________________________________________________ -->
383 <div class="doc_subsection"><a name="copyright">Copyright</a></div>
384 <div class="doc_text">
386 <p>For consistency and ease of management, the project requires the
387 copyright for all LLVM software to be held by a single copyright holder.
388 Although UIUC may assign the copyright of the software to another entity,
389 the intent for the project is to always have a single entity hold the copy
390 rights to LLVM at any given time.
391 <p>Having multiple copyright holders for various portions of LLVM is
392 problematic in the management of the software. Having a single copyright
393 holder is in the best interests of all developers and users as it greatly
394 reduces the managerial burden for any kind of administrative or technical
395 decisions about LLVM.</p>
397 <!-- _______________________________________________________________________ -->
398 <div class="doc_subsection"><a name="license">License</a></div>
399 <div class="doc_text">
400 <p>LLVM licensing decisions will be made by the LLVM Oversight Group. Any
401 issues, comments or suggestions with the licensing should be sent to the
402 <a href="mailto:llvm-oversight@cs.uiuc.edu">LLVM Oversight Group</a>.</p>
403 <p>The LLVM Oversight Group intends to keep LLVM perpetually open source
404 and to use liberal open source licenses. The current license is the
405 <a href="http://www.opensource.org/licenses/UoI-NCSA.php">
406 University of Illinois/NCSA Open Source License</a>, which boils
409 <li>You can freely distribute LLVM.</li>
410 <li>You must retain the copyright notice if you redistribute LLVM.</li>
411 <li>Binaries derived from LLVM must reproduce the copyright notice.</li>
412 <li>You can't use our names to promote your LLVM derived products.</li>
413 <li>There's no warranty on LLVM at all.</li>
415 <p>We believe this fosters the widest adoption of LLVM because it allows
416 commercial products to be derived from LLVM with few restrictions and
417 without a requirement for making any derived works also open source (i.e.
418 LLVM's license is not a <i>copyleft</i> license). We suggest that you read
419 the <a href="http://www.opensource.org/licenses/UoI-NCSA.php">License</a>
420 if further clarification is needed.</p>
422 <!-- _______________________________________________________________________ -->
423 <div class="doc_subsection"><a name="devagree">Developer Agreements</a></div>
424 <div class="doc_text">
425 <p>With regards to the LLVM copyright and licensing, developers agree to:</p>
427 <li>assign their copy rights to UIUC for any contribution made so that
428 the entire software base can be managed by a single copyright holder.</li>
429 <li>allow their contribution(s) to be licensed as open source by the then
430 current license chosen by the LLVM Oversight Group.</li>
434 <!--=========================================================================-->
435 <div class="doc_section"><a name="terms">Terminology</a></div>
436 <!--=========================================================================-->
437 <div class="doc_text">
438 <p>So that the policies defined in this document are clear, we define some
441 <dt><a name="t_change">Change</a></dt>
442 <dd>Any modification to LLVM including documentation, tests, build system,
443 etc. either in <a href="#t_patch">patch</a> or
444 <a href="#t_commit">commit</a> form.</dd>
445 <dt><a name="t_commit">Commit</a><dt>
446 <dd>A <a href="t_change">change</a> submitted directly to LLVM software
447 repository via the <tt>cvs commit</tt> command.</dd>
448 <dt><a name="t_copleft">Copyleft</a></dt>
449 <dd>A licensing policy that requires the licensee to adopt the terms of the
450 license for <i>derived</i> works. LLVM does not subscribe to this
452 <dt><a name="t_developer">Developer</a></dt>
453 <dd>Anyone who submits a <a href="#t_change">change</a> to LLVM.</dd>
454 <dt><a name="t_inrement">Increment</a></dt>
455 <dd>A <a href="#t_change">change</a> or set of changes, whether by
456 <a href="#t_patch">patch</a> or <a href="#t_commit">commit</a>, that are
457 related by a single common purpose. Increments are atomic as they
458 leave LLVM in a stable state (both compiling and working properly).</dd>
459 <dt><a name="t_must">Must</a></dt>
460 <dd>When used in a policy statement, the term <i>must</i> implies a
461 non-optional requirement on the developer.</dd>
462 <dt><a name="t_patch">Patch</a></dt>
463 <dd>A <a href="#t_change">change</a> submitted by email in patch (diff)
464 format generated by the <tt>cvs diff</tt> command.</dd>
465 <dt><a name="t_should">Should</a></dt>
466 <dd>When used in a policy statement, the term <i>should</i> implies a
467 recommended but optional requirement on the developer.</dd>
471 <!--=========================================================================-->
472 <div class="doc_section"><a name="polnotes">Policy Notes</a></div>
473 <!--=========================================================================-->
474 <div class="doc_text">
475 <p>This section contains some notes on policy topics that need to be
476 resolved and incorporated into the main body of the document above.</p>
478 <li>When to open a new bug and when to re-use an existing one. For example
479 PR1158. If the same assertion happens do you open a new bug or reopen
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