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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="#terms">Terminology</a></li>
17 <li><a href="#general">General Policies</a>
19 <li><a href="#informed">Stay Informed</a> </li>
20 <li><a href="#newwork">Starting New Work</a></li>
21 <li><a href="#reviews">Code Reviews</a></li>
22 <li><a href="#incremental">Incremental Development</a></li>
23 <li><a href="#quality">Quality</a></li>
24 <li><a href="#testcases">Test Cases</a></li>
26 <li><a href="#patches">Patch Policies</a>
28 <li><a href="#p_form">Patch Form</a></li>
29 <li><a href="#p_testing">Patch Testing</a></li>
30 <li><a href="#p_submission">Patch Submission</a></li>
31 <li><a href="#p_after">After Submission</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>
43 <div class="doc_author">Written by LLVM Oversight Team</div>
44 </td><td class="layout">
46 <!--=========================================================================-->
47 <div class="doc_section"><a name="overview">Overview</a></div>
48 <!--=========================================================================-->
49 <div class="doc_text">
50 <p>This document contains the LLVM Developer Policy which defines the
51 project's policy towards developers and their contributions. The intent of
52 this policy is to eliminate mis-communication, rework, and confusion that
53 might arise from the distributed nature of LLVM's development. By stating
54 the policy in clear terms, we hope each developer can know ahead of time
55 what to expect when making LLVM contributions.</p>
57 <!--=========================================================================-->
58 <div class="doc_section"><a name="terms">Terminology</a></div>
59 <!--=========================================================================-->
60 <div class="doc_text">
61 <p>So that the policies defined in the next sections are clear, we first
62 define some terms here.</p>
64 <dt><a name="t_change">Change</a></dt>
65 <dd>Any modification to LLVM including documentation, tests, build system,
66 etc. either in <a href="#t_patch">patch</a> or
67 <a href="#t_commit">commit</a> form.</dd>
68 <dt><a name="t_commit">Commit</a><dt>
69 <dd>A <a href="t_change">change</a> submitted directly to LLVM software
70 repository via the <tt>cvs commit</tt> command.</dd>
71 <dt><a name="t_developer">Developer</a></dt>
72 <dd>Anyone who submits a <a href="#t_change">change</a> to LLVM.</dd>
73 <dt><a name="t_inrement">Increment</a></dt>
74 <dd>A <a href="#t_change">change</a> or set of changes, whether by
75 <a href="#t_patch">patch</a> or <a href="#t_commit">commit</a>, that are
76 related by a single common purpose. Increments are atomic as they
77 leave LLVM in a stable state (both compiling and working properly).</dd>
78 <dt><a name="t_must">Must</a></dt>
79 <dd>When used in a policy statement, the term <i>must</i> implies a
80 non-optional requirement on the developer.</dd>
81 <dt><a name="t_patch">Patch</a></dt>
82 <dd>A <a href="#t_change">change</a> submitted by email in patch (diff)
83 format generated by the <tt>cvs diff</tt> command.</dd>
84 <dt><a name="t_should">Should</a></dt>
85 <dd>When used in a policy statement, the term <i>should</i> implies a
86 recommended but optional requirement on the developer.</dd>
92 <!--=========================================================================-->
93 <div class="doc_section"><a name="general">General Policies</a></div>
94 <!--=========================================================================-->
95 <div class="doc_text">
96 <p>This section contains policies that pertain generally to LLVM developers.
97 <p>LLVM Developers are expected to meet the following obligations in order
98 for LLVM to maintain a high standard of quality.<p>
101 <!-- _______________________________________________________________________ -->
102 <div class="doc_subsection"> <a name="informed">Stay Informed</a> </div>
103 <div class="doc_text">
104 <p>Developers should stay informed by reading at least the
105 <a href="mailto:llvmdev@llvm.org">llvmdev</a> email list. If you are doing
106 anything more than just casual work on LLVM, it is highly suggested that you
107 also subscribe to the llvm-commits list and pay attention to changes being
109 <p>We recommend that active developers register an email account with
110 <a href="http://llvm.org/bugs/">LLVM Bugzilla</a> and preferably subscribe to
111 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmbugs">llvm-bugs</a>
112 email list to keep track of bugs and enhancements occurring in LLVM.</p>
115 <!-- _______________________________________________________________________ -->
116 <div class="doc_subsection"> <a name="newwork">Starting New Work</a></div>
117 <div class="doc_text">
118 <p>When a developer begins a major new project with the aim of contributing
119 it back to LLVM, s/he should inform the community with an email to
120 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">llvm-dev</a>
121 email list, to the extent possible. The reason for this is to:
123 <li>keep the community informed about future changes to LLVM, </li>
124 <li>avoid duplication of effort by having multiple parties working on the
125 same thing and not knowing about it, and</li>
126 <li>ensure that any issues around the proposed work are discussed and
127 resolved before any significant work is accomplished.</li>
129 <p>The design of LLVM is carefully controlled to ensure that all the pieces
130 fit together well. If you plan to make a major change to the way LLVM works or
131 a major new extension, it is a good idea to get consensus with the development
132 community before you start working on it.</p>
135 <!-- _______________________________________________________________________ -->
136 <div class="doc_subsection"> <a name="reviews">Code Reviews</a></div>
137 <div class="doc_text">
138 <p>LLVM has a code review policy. Code review is an excellent way to ensure
139 high quality in the software. The following policies apply:</p>
141 <li>All developers are required to have any significant changes reviewed
142 before they are committed to the repository.</li>
143 <li>Code reviews are conducted by email.</li>
144 <li>Code can be reviewed either before it is committed or after.</li>
145 <li>The developer responsible for a code change is also responsible for
146 making all necessary review changes.</li>
147 <li>Developers should participate in code reviews as both a reviewer and
148 a reviewee. We don't have a dedicated team of reviewers. If someone is
149 kind enough to review your code, you should return the favor for someone
154 <!-- _______________________________________________________________________ -->
155 <div class="doc_subsection"> <a name="incremental">Incremental Development</a>
157 <div class="doc_text">
158 <p>LLVM uses an incremental development style and all developers are expected
159 to follow this practice. Incremental development is a big key to LLVM's
160 success and it is essential that developers submit incremental patches. The
161 following defines the incremental development approach:</p>
163 <li>The first task is to define the increment and get consensus (with the
164 LLVM development community) on what the end goal of the change is. Making
165 random small changes that go nowhere is not useful for anyone.</li>
166 <li>An increment is the smallest patch size necessary to effect one change
168 <li>Increments can be stand alone (e.g. to fix a bug), or part of a planned
169 series of increments towards some development goal.</li>
170 <li>Increments should be kept as small as possible. This simplifies your
171 work (into a logical progression), simplifies code review and reduces the
172 chance that you will get negative feedback on the change. Small increments
173 also facilitate the maintenance of a high quality code base.</li>
177 <!-- _______________________________________________________________________ -->
178 <div class="doc_subsection"> <a name="quality">Quality</a></div>
179 <div class="doc_text">
180 <p>The minimum quality standards for any change to the main development
183 <li>Code must adhere to the
184 <a href="CodingStandards.html">LLVM Coding Standards</a>.</li>
185 <li>Code must compile cleanly (no errors, no warnings) on at least one
187 <li>Code must pass the deja gnu (llvm/test) test suite.</li>
189 <p>Additionally, the committer is responsible for addressing all of the
190 following items (preferably before submission):</p>
192 <li>The code should compile cleanly on all platforms.</li>
193 <li>The changes should not cause regressions in the <tt>llvm-test</tt>
194 suite including SPEC CINT2000, SPEC CFP2000, SPEC CINT2006, and
196 <li>The change set should not cause performance or correctness regressions
197 for the LLVM tools.</li>
198 <li>The changes should not cause performance or correctness regressions in
199 code compiled with LLVM on all applicable targets.</li>
203 <!-- _______________________________________________________________________ -->
204 <div class="doc_subsection"> <a name="testcases">Test Cases</a></div>
205 <div class="doc_text">
206 <p>Developers are required to create test cases for regressions and new
207 features and include them with their changes. The following policies
210 <li>All feature and regression test cases must be added to the
211 <tt>llvm/test</tt> directory. The appropriate sub-directory should be
212 selected (see the <a href="TestingGuide.html">Testing Guide</a> for
214 <li>Test cases should be written in LLVM assembly language unless the
215 feature or regression being tested requires another language (e.g. the
216 bug being fixed or feature being implemented is in the lvm-gcc C++
218 <li>Test cases, especially for regressions, should be much as reduced as
219 possible, by <a href="CommandGuide/html/bugpoint.html">bugpoint</a> or
220 manually. It is unacceptable
221 to place an entire failing program into <tt>llvm/test</tt> as this creates
222 a <i>time-to-test</i> burden on all developers. Keep them short!</li>
223 <li>More extensive test cases (applications, benchmarks, etc.) should be
224 added to the <tt>llvm-test</tt> test suite. This test suite is for
225 coverage not features or regressions.</li>
229 <!--=========================================================================-->
230 <div class="doc_section"><a name="patches">Patch Policies</a></div>
231 <!--=========================================================================-->
232 <div class="doc_text">
233 <p>This section contains policies that pertain to submitting patches
234 to LLVM and committing code to the repository</p>
236 <!-- _______________________________________________________________________ -->
237 <div class="doc_subsection"> <a name="p_form">Patch Form</a></div>
238 <div class="doc_text">
239 <p>When submitting a patch, developers must follow these rules:</p>
241 <li>Patches must be made against the CVS HEAD (main development trunk),
243 <li>Patches should be made with this command:<pre>
244 cvs diff -Ntdup -5</pre> or with the utility <tt>utils/mkpatch</tt>.</li>
245 <li>Patches should not include differences in generated code such as the
246 code generated by <tt>flex</tt>, <tt>bison</tt> or <tt>tblgen</tt>. The
247 <tt>utils/mkpatch</tt> utility takes care of this for you.</li>
250 <!-- _______________________________________________________________________ -->
251 <div class="doc_subsection"> <a name="p_testing">Patch Testing</a></div>
252 <div class="doc_text">
253 <p>Before a patch is submitted for review, it should be tested to ensure
256 <li>The patch must compile against the CVS HEAD cleanly (zero warnings, zero
258 <li>All the llvm/test (Deja Gnu) tests must pass.</li>
259 <li>All the llvm-test tests must pass on at least one platform.</li>
262 <!-- _______________________________________________________________________ -->
263 <div class="doc_subsection"> <a name="p_submission">Patch Submission</a></div>
264 <div class="doc_text">
265 <p>When a patch is ready to be submitted, these policies apply:</p>
267 <li>Patches should be submitted immediately after they are generated. Stale
268 patches may not apply correctly if the underlying code changes between the
269 time the patch was created and the time it is applied.</li>
270 <li>Patches should be submitted by e-mail to the
271 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">
272 llvm-commits</a> list.</li>
276 <!-- _______________________________________________________________________ -->
277 <div class="doc_subsection"> <a name="p_after">After Submission</a></div>
278 <div class="doc_text">
279 <p>After a patch has been submitted, these policies apply:</p>
281 <li>The patch is subject to review by anyone on the llvm-commits email list.
283 <li>Changes recommended by a reviewer should be incorporated into your
284 patch or you should explain why the reviewer is incorrect. This process
285 iterates until there are no more review comments.</li>
286 <li>If the submitter believes the review comment is in error, a response to
287 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">
288 llvm-commits</a> list should be made explaining why the recommendation
289 cannot be followed.</li>
293 <!-- _______________________________________________________________________ -->
294 <div class="doc_subsection"> <a name="p_after">After Commit</a></div>
295 <div class="doc_text">
296 <p>After a patch has been committed, these policies apply:</p>
298 <li>The patch is subject to further review by anyone on the llvm-commits
300 <li>The patch submitter is responsible for all aspects of the patch per
301 the <a href="quality">quality policy</a> above.</li>
302 <li>If the patch is discovered to not meet the
303 <a href="quality">quality standards</a> standards within a reasonable time
304 frame (24 hours), it may be subject to reversal.</li>
308 <!-- _______________________________________________________________________ -->
309 <div class="doc_subsection"> <a name="c_access">Gaining Commit Access</a></div>
310 <div class="doc_text">
311 <p>Commit access to the repository is granted according to this policy:</p>
313 <li>Commit access is not granted to anyone unless they specifically ask for
315 <li>Requests for commit access must be sent to the
316 <a href="mailto:llvm-oversight@cs.uiuc.edu">LLVM Oversight Group</a>.</li>
317 <li>Granting commit access is at the sole discretion of the LLVM Oversight
320 <p>Submitting patches to LLVM via the patch policy above will greatly
321 increase the chance that your request for commit access is granted. Getting
322 to know the members of the LLVM community (email, IRC, in person contact,
323 etc.) will also increase your chances.</p>
327 <!-- _______________________________________________________________________ -->
328 <div class="doc_subsection"> <a name="c_new">New Committers</a></div>
329 <div class="doc_text">
330 <p>For those who have recently obtained commit access, the following policies
333 <li>You are granted <i>commit-after-approval</i> to all parts of LLVM.
334 To get approval, submit a patch to
335 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>
336 per the patch policies above. When approved you may commit it
338 <li>You are allowed to commit patches without approval which you think are
339 obvious. This is clearly a subjective decision. We simply expect you to
340 use good judgement.</li>
341 <li>You are granted <i>commit-without-approval</i> to those portions of LLVM
342 that you own (contributed) or maintain (have been assigned responsibility
343 for), with the proviso that such commits must not break the build. This is
344 a "trust but verify" policy and commits of this nature are reviewed after
345 they are committed.</li>
346 <li>Commits that violate the <a href="quality">quality standards</a> may
347 be reverted. This is necessary when the change blocks other developers from
348 making progress. The developers is welcome to re-commit the change after
349 the problem has been fixed.</li>
350 <li>Multiple violations of these policies or a single egregious violation
351 may cause commit access to be revoked.</li>
355 <!--=========================================================================-->
356 <div class="doc_section"><a name="candl">Copyright and License</a></div>
357 <!--=========================================================================-->
358 <div class="doc_text">
359 <p>We address here the issues of copyright and license for the LLVM project.
360 The object of the copyright and license is the LLVM source and documentation.
361 Currently, the University of Illinois is the LLVM copyright holder and the
362 terms of its license to LLVM users and developers is the
363 <a href="http://www.opensource.org/licenses/UoI-NCSA.php">University of
364 Illinois/NCSA Open Source License</a>.
367 <div class="doc_notes">
368 <p>NOTE: This section deals with legal matters but does not provide legal
369 advice. It is intended only as a general guideline.</p>
372 <!-- _______________________________________________________________________ -->
373 <div class="doc_subsection"><a name="attribution">Attribution</a></div>
374 <div class="doc_text">
375 <p>The LLVM project believes in correct attribution of contributions to
376 their contributors, as follows:</p>
378 <li>Developers who originate new files in LLVM should place their name at
379 the top of the file per the
380 <a href="CodingStandards.html">Coding Standards</a>.</li>
381 <li>There should be only one name at the top of the file and it should be
382 the person who created the file.</li>
383 <li>Placing your name in the file does not imply copyright but does
384 correctly attribute the file to its author.</li>
385 <li>Developers should be aware that after some time has passed, the name at
386 the top of a file may become meaningless as maintenance/ownership of files
388 <li>Developers should submit or commit patches to the
389 <a href="http://llvm.org/cvsweb/cvsweb.cgi/llvm/CREDITS.TXT?rev=1.67&content-type=text/x-cvsweb-markup">CREDITS.txt</a>
390 file to summarize their contributions.</li>
391 <li>Commit comments should contain correct attribution of the person who s
392 submitted the patch if that person is not the committer (i.e. when a
393 developer with commit privileges commits a patch for someone else).</li>
397 <!-- _______________________________________________________________________ -->
398 <div class="doc_subsection"><a name="copyright">Copyright</a></div>
399 <div class="doc_text">
401 <p>However, for consistency and ease of management, the project requires the
402 copyright for all LLVM software to be held by a single copyright holder.
403 Although UIUC may assign the copyright of the software to another entity,
404 the intent for the project is to always have a single entity hold the copy
405 rights to LLVM at any given time.
406 <p>Having multiple copyright holders for various portions of LLVM is
407 problematic in the management of the software. Having a single copyright
408 holder is in the best interests of all developers and users as it greatly
409 reduces the managerial burden for any kind of administrative or technical
410 decisions about LLVM.</p>
412 <!-- _______________________________________________________________________ -->
413 <div class="doc_subsection"><a name="license">License</a></div>
414 <div class="doc_text">
415 <p>LLVM licensing decisions will be made by the LLVM Oversight Group. Any
416 issues, comments or suggestions with the licensing should be sent to the
417 <a href="mailto:llvm-oversight@cs.uiuc.edu">LLVM Oversight Group</a>.</p>
418 <p>The LLVM Oversight Group intends to keep LLVM perpetually open source
419 and to use liberal open source licenses. The current license is the
420 University of Illinois Open Source License (see LICENSE.TXT), which boils
423 <li>You can freely distribute LLVM.</li>
424 <li>You must retain the copyright notice if you redistribute LLVM.</li>
425 <li>Binaries derived from LLVM must reproduce the copyright notice.</li>
426 <li>You can't use our names to promote your LLVM derived products.</li>
427 <li>There's no warranty on LLVM at all.</li>
429 <p>We believe this fosters the widest adoption of LLVM because it allows
430 commercial products to be derived from LLVM with few restrictions and
431 without a requirement for making any derived works also open source. We
432 suggest that you read the
433 <a href="http://www.opensource.org/licenses/UoI-NCSA.php">License</a> if
434 further clarification is needed.</p>
436 <!-- _______________________________________________________________________ -->
437 <div class="doc_subsection"><a name="devagree">Developer Agreements</a></div>
438 <div class="doc_text">
439 <p>With regards to the LLVM copyright and licensing, developers agree to:</p>
441 <li>assign their copy rights to UIUC for any contribution made so that
442 the entire software base can be managed by a single copyright holder.</li>
443 <li>allow their contribution(s) to be licensed as open source by the then
444 current license chosen by the LLVM Oversight Group.</li>
448 <!--=========================================================================-->
449 <div class="doc_section"><a name="notes">Policy Notes</a></div>
450 <!--=========================================================================-->
451 <div class="doc_text">
452 <p>This section contains some notes on policy topics that need to be
453 resolved and incorporated into the main body of the document above.</p>
455 <li>When to open a new bug and when to re-use an existing one. For example
456 PR1158. If the same assertion happens do you open a new bug or reopen
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