1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" 2 "http://www.w3.org/TR/html4/strict.dtd"> 3 <html> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 6 <title>LLVM Developer Policy</title> 7 <link rel="stylesheet" href="llvm.css" type="text/css"> 8 </head> 9 <body> 10 11 <h1>LLVM Developer Policy</h1> 12 <ol> 13 <li><a href="#introduction">Introduction</a></li> 14 <li><a href="#policies">Developer Policies</a> 15 <ol> 16 <li><a href="#informed">Stay Informed</a></li> 17 <li><a href="#patches">Making a Patch</a></li> 18 <li><a href="#reviews">Code Reviews</a></li> 19 <li><a href="#owners">Code Owners</a></li> 20 <li><a href="#testcases">Test Cases</a></li> 21 <li><a href="#quality">Quality</a></li> 22 <li><a href="#commitaccess">Obtaining Commit Access</a></li> 23 <li><a href="#newwork">Making a Major Change</a></li> 24 <li><a href="#incremental">Incremental Development</a></li> 25 <li><a href="#attribution">Attribution of Changes</a></li> 26 </ol></li> 27 <li><a href="#clp">Copyright, License, and Patents</a> 28 <ol> 29 <li><a href="#copyright">Copyright</a></li> 30 <li><a href="#license">License</a></li> 31 <li><a href="#patents">Patents</a></li> 32 </ol></li> 33 </ol> 34 <div class="doc_author">Written by the LLVM Oversight Team</div> 35 36 <!--=========================================================================--> 37 <h2><a name="introduction">Introduction</a></h2> 38 <!--=========================================================================--> 39 <div> 40 <p>This document contains the LLVM Developer Policy which defines the project's 41 policy towards developers and their contributions. The intent of this policy 42 is to eliminate miscommunication, rework, and confusion that might arise from 43 the distributed nature of LLVM's development. By stating the policy in clear 44 terms, we hope each developer can know ahead of time what to expect when 45 making LLVM contributions. This policy covers all llvm.org subprojects, 46 including Clang, LLDB, etc.</p> 47 <p>This policy is also designed to accomplish the following objectives:</p> 48 49 <ol> 50 <li>Attract both users and developers to the LLVM project.</li> 51 52 <li>Make life as simple and easy for contributors as possible.</li> 53 54 <li>Keep the top of Subversion trees as stable as possible.</li> 55 </ol> 56 57 <p>This policy is aimed at frequent contributors to LLVM. People interested in 58 contributing one-off patches can do so in an informal way by sending them to 59 the 60 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits 61 mailing list</a> and engaging another developer to see it through the 62 process.</p> 63 </div> 64 65 <!--=========================================================================--> 66 <h2><a name="policies">Developer Policies</a></h2> 67 <!--=========================================================================--> 68 <div> 69 <p>This section contains policies that pertain to frequent LLVM developers. We 70 always welcome <a href="#patches">one-off patches</a> from people who do not 71 routinely contribute to LLVM, but we expect more from frequent contributors 72 to keep the system as efficient as possible for everyone. Frequent LLVM 73 contributors are expected to meet the following requirements in order for 74 LLVM to maintain a high standard of quality.<p> 75 76 <!-- _______________________________________________________________________ --> 77 <h3><a name="informed">Stay Informed</a></h3> 78 <div> 79 <p>Developers should stay informed by reading at least the "dev" mailing list 80 for the projects you are interested in, such as 81 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">llvmdev</a> for 82 LLVM, <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">cfe-dev</a> 83 for Clang, or <a 84 href="http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev">lldb-dev</a> 85 for LLDB. If you are doing anything more than just casual work on LLVM, it 86 is suggested that you also subscribe to the "commits" mailing list for the 87 subproject you're interested in, such as 88 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>, 89 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits">cfe-commits</a>, 90 or <a href="http://lists.cs.uiuc.edu/mailman/listinfo/lldb-commits">lldb-commits</a>. 91 Reading the "commits" list and paying attention to changes being made by 92 others is a good way to see what other people are interested in and watching 93 the flow of the project as a whole.</p> 94 95 <p>We recommend that active developers register an email account with 96 <a href="http://llvm.org/bugs/">LLVM Bugzilla</a> and preferably subscribe to 97 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmbugs">llvm-bugs</a> 98 email list to keep track of bugs and enhancements occurring in LLVM. We 99 really appreciate people who are proactive at catching incoming bugs in their 100 components and dealing with them promptly.</p> 101 </div> 102 103 <!-- _______________________________________________________________________ --> 104 <h3><a name="patches">Making a Patch</a></h3> 105 106 <div> 107 <p>When making a patch for review, the goal is to make it as easy for the 108 reviewer to read it as possible. As such, we recommend that you:</p> 109 110 <ol> 111 <li>Make your patch against the Subversion trunk, not a branch, and not an old 112 version of LLVM. This makes it easy to apply the patch. For information 113 on how to check out SVN trunk, please see the <a 114 href="GettingStarted.html#checkout">Getting Started Guide</a>.</li> 115 116 <li>Similarly, patches should be submitted soon after they are generated. Old 117 patches may not apply correctly if the underlying code changes between the 118 time the patch was created and the time it is applied.</li> 119 120 <li>Patches should be made with <tt>svn diff</tt>, or similar. If you use 121 a different tool, make sure it uses the <tt>diff -u</tt> format and 122 that it doesn't contain clutter which makes it hard to read.</li> 123 124 <li>If you are modifying generated files, such as the top-level 125 <tt>configure</tt> script, please separate out those changes into 126 a separate patch from the rest of your changes.</li> 127 </ol> 128 129 <p>When sending a patch to a mailing list, it is a good idea to send it as an 130 <em>attachment</em> to the message, not embedded into the text of the 131 message. This ensures that your mailer will not mangle the patch when it 132 sends it (e.g. by making whitespace changes or by wrapping lines).</p> 133 134 <p><em>For Thunderbird users:</em> Before submitting a patch, please open 135 <em>Preferences → Advanced → General → Config Editor</em>, 136 find the key <tt>mail.content_disposition_type</tt>, and set its value to 137 <tt>1</tt>. Without this setting, Thunderbird sends your attachment using 138 <tt>Content-Disposition: inline</tt> rather than <tt>Content-Disposition: 139 attachment</tt>. Apple Mail gamely displays such a file inline, making it 140 difficult to work with for reviewers using that program.</p> 141 </div> 142 143 <!-- _______________________________________________________________________ --> 144 <h3><a name="reviews">Code Reviews</a></h3> 145 <div> 146 <p>LLVM has a code review policy. Code review is one way to increase the quality 147 of software. We generally follow these policies:</p> 148 149 <ol> 150 <li>All developers are required to have significant changes reviewed before 151 they are committed to the repository.</li> 152 153 <li>Code reviews are conducted by email, usually on the llvm-commits 154 list.</li> 155 156 <li>Code can be reviewed either before it is committed or after. We expect 157 major changes to be reviewed before being committed, but smaller changes 158 (or changes where the developer owns the component) can be reviewed after 159 commit.</li> 160 161 <li>The developer responsible for a code change is also responsible for making 162 all necessary review-related changes.</li> 163 164 <li>Code review can be an iterative process, which continues until the patch 165 is ready to be committed.</li> 166 </ol> 167 168 <p>Developers should participate in code reviews as both reviewers and 169 reviewees. If someone is kind enough to review your code, you should return 170 the favor for someone else. Note that anyone is welcome to review and give 171 feedback on a patch, but only people with Subversion write access can approve 172 it.</p> 173 </div> 174 175 <!-- _______________________________________________________________________ --> 176 <h3><a name="owners">Code Owners</a></h3> 177 <div> 178 179 <p>The LLVM Project relies on two features of its process to maintain rapid 180 development in addition to the high quality of its source base: the 181 combination of code review plus post-commit review for trusted maintainers. 182 Having both is a great way for the project to take advantage of the fact that 183 most people do the right thing most of the time, and only commit patches 184 without pre-commit review when they are confident they are right.</p> 185 186 <p>The trick to this is that the project has to guarantee that all patches that 187 are committed are reviewed after they go in: you don't want everyone to 188 assume someone else will review it, allowing the patch to go unreviewed. To 189 solve this problem, we have a notion of an 'owner' for a piece of the code. 190 The sole responsibility of a code owner is to ensure that a commit to their 191 area of the code is appropriately reviewed, either by themself or by someone 192 else. The current code owners are:</p> 193 194 <ol> 195 <li><b>Evan Cheng</b>: Code generator and all targets.</li> 196 197 <li><b>Greg Clayton</b>: LLDB.</li> 198 199 <li><b>Doug Gregor</b>: Clang Frontend Libraries.</li> 200 201 <li><b>Howard Hinnant</b>: libc++.</li> 202 203 <li><b>Anton Korobeynikov</b>: Exception handling, debug information, and 204 Windows codegen.</li> 205 206 <li><b>Ted Kremenek</b>: Clang Static Analyzer.</li> 207 208 <li><b>Chris Lattner</b>: Everything not covered by someone else.</li> 209 210 <li><b>John McCall</b>: Clang LLVM IR generation.</li> 211 212 <li><b>Jakob Olesen</b>: Register allocators and TableGen.</li> 213 214 <li><b>Duncan Sands</b>: dragonegg and llvm-gcc 4.2.</li> 215 </ol> 216 217 <p>Note that code ownership is completely different than reviewers: anyone can 218 review a piece of code, and we welcome code review from anyone who is 219 interested. Code owners are the "last line of defense" to guarantee that all 220 patches that are committed are actually reviewed.</p> 221 222 <p>Being a code owner is a somewhat unglamorous position, but it is incredibly 223 important for the ongoing success of the project. Because people get busy, 224 interests change, and unexpected things happen, code ownership is purely 225 opt-in, and anyone can choose to resign their "title" at any time. For now, 226 we do not have an official policy on how one gets elected to be a code 227 owner.</p> 228 </div> 229 230 <!-- _______________________________________________________________________ --> 231 <h3><a name="testcases">Test Cases</a></h3> 232 <div> 233 <p>Developers are required to create test cases for any bugs fixed and any new 234 features added. Some tips for getting your testcase approved:</p> 235 236 <ol> 237 <li>All feature and regression test cases are added to the 238 <tt>llvm/test</tt> directory. The appropriate sub-directory should be 239 selected (see the <a href="TestingGuide.html">Testing Guide</a> for 240 details).</li> 241 242 <li>Test cases should be written in <a href="LangRef.html">LLVM assembly 243 language</a> unless the feature or regression being tested requires 244 another language (e.g. the bug being fixed or feature being implemented is 245 in the llvm-gcc C++ front-end, in which case it must be written in 246 C++).</li> 247 248 <li>Test cases, especially for regressions, should be reduced as much as 249 possible, by <a href="Bugpoint.html">bugpoint</a> or manually. It is 250 unacceptable to place an entire failing program into <tt>llvm/test</tt> as 251 this creates a <i>time-to-test</i> burden on all developers. Please keep 252 them short.</li> 253 </ol> 254 255 <p>Note that llvm/test and clang/test are designed for regression and small 256 feature tests only. More extensive test cases (e.g., entire applications, 257 benchmarks, etc) 258 should be added to the <tt>llvm-test</tt> test suite. The llvm-test suite is 259 for coverage (correctness, performance, etc) testing, not feature or 260 regression testing.</p> 261 </div> 262 263 <!-- _______________________________________________________________________ --> 264 <h3><a name="quality">Quality</a></h3> 265 <div> 266 <p>The minimum quality standards that any change must satisfy before being 267 committed to the main development branch are:</p> 268 269 <ol> 270 <li>Code must adhere to the <a href="CodingStandards.html">LLVM Coding 271 Standards</a>.</li> 272 273 <li>Code must compile cleanly (no errors, no warnings) on at least one 274 platform.</li> 275 276 <li>Bug fixes and new features should <a href="#testcases">include a 277 testcase</a> so we know if the fix/feature ever regresses in the 278 future.</li> 279 280 <li>Code must pass the <tt>llvm/test</tt> test suite.</li> 281 282 <li>The code must not cause regressions on a reasonable subset of llvm-test, 283 where "reasonable" depends on the contributor's judgement and the scope of 284 the change (more invasive changes require more testing). A reasonable 285 subset might be something like 286 "<tt>llvm-test/MultiSource/Benchmarks</tt>".</li> 287 </ol> 288 289 <p>Additionally, the committer is responsible for addressing any problems found 290 in the future that the change is responsible for. For example:</p> 291 292 <ul> 293 <li>The code should compile cleanly on all supported platforms.</li> 294 295 <li>The changes should not cause any correctness regressions in the 296 <tt>llvm-test</tt> suite and must not cause any major performance 297 regressions.</li> 298 299 <li>The change set should not cause performance or correctness regressions for 300 the LLVM tools.</li> 301 302 <li>The changes should not cause performance or correctness regressions in 303 code compiled by LLVM on all applicable targets.</li> 304 305 <li>You are expected to address any <a href="http://llvm.org/bugs/">bugzilla 306 bugs</a> that result from your change.</li> 307 </ul> 308 309 <p>We prefer for this to be handled before submission but understand that it 310 isn't possible to test all of this for every submission. Our build bots and 311 nightly testing infrastructure normally finds these problems. A good rule of 312 thumb is to check the nightly testers for regressions the day after your 313 change. Build bots will directly email you if a group of commits that 314 included yours caused a failure. You are expected to check the build bot 315 messages to see if they are your fault and, if so, fix the breakage.</p> 316 317 <p>Commits that violate these quality standards (e.g. are very broken) may be 318 reverted. This is necessary when the change blocks other developers from 319 making progress. The developer is welcome to re-commit the change after the 320 problem has been fixed.</p> 321 </div> 322 323 <!-- _______________________________________________________________________ --> 324 <h3><a name="commitaccess">Obtaining Commit Access</a></h3> 325 <div> 326 327 <p>We grant commit access to contributors with a track record of submitting high 328 quality patches. If you would like commit access, please send an email to 329 <a href="mailto:sabre (a] nondot.org">Chris</a> with the following 330 information:</p> 331 332 <ol> 333 <li>The user name you want to commit with, e.g. "hacker".</li> 334 335 <li>The full name and email address you want message to llvm-commits to come 336 from, e.g. "J. Random Hacker <hacker (a] yoyodyne.com>".</li> 337 338 <li>A "password hash" of the password you want to use, e.g. "2ACR96qjUqsyM". 339 Note that you don't ever tell us what your password is, you just give it 340 to us in an encrypted form. To get this, run "htpasswd" (a utility that 341 comes with apache) in crypt mode (often enabled with "-d"), or find a web 342 page that will do it for you.</li> 343 </ol> 344 345 <p>Once you've been granted commit access, you should be able to check out an 346 LLVM tree with an SVN URL of "https://username@llvm.org/..." instead of the 347 normal anonymous URL of "http://llvm.org/...". The first time you commit 348 you'll have to type in your password. Note that you may get a warning from 349 SVN about an untrusted key, you can ignore this. To verify that your commit 350 access works, please do a test commit (e.g. change a comment or add a blank 351 line). Your first commit to a repository may require the autogenerated email 352 to be approved by a mailing list. This is normal, and will be done when 353 the mailing list owner has time.</p> 354 355 <p>If you have recently been granted commit access, these policies apply:</p> 356 357 <ol> 358 <li>You are granted <i>commit-after-approval</i> to all parts of LLVM. To get 359 approval, submit a <a href="#patches">patch</a> to 360 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits">llvm-commits</a>. 361 When approved you may commit it yourself.</li> 362 363 <li>You are allowed to commit patches without approval which you think are 364 obvious. This is clearly a subjective decision — we simply expect 365 you to use good judgement. Examples include: fixing build breakage, 366 reverting obviously broken patches, documentation/comment changes, any 367 other minor changes.</li> 368 369 <li>You are allowed to commit patches without approval to those portions of 370 LLVM that you have contributed or maintain (i.e., have been assigned 371 responsibility for), with the proviso that such commits must not break the 372 build. This is a "trust but verify" policy and commits of this nature are 373 reviewed after they are committed.</li> 374 375 <li>Multiple violations of these policies or a single egregious violation may 376 cause commit access to be revoked.</li> 377 </ol> 378 379 <p>In any case, your changes are still subject to <a href="#reviews">code 380 review</a> (either before or after they are committed, depending on the 381 nature of the change). You are encouraged to review other peoples' patches 382 as well, but you aren't required to.</p> 383 </div> 384 385 <!-- _______________________________________________________________________ --> 386 <h3><a name="newwork">Making a Major Change</a></h3> 387 <div> 388 <p>When a developer begins a major new project with the aim of contributing it 389 back to LLVM, s/he should inform the community with an email to 390 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev">llvmdev</a> 391 email list, to the extent possible. The reason for this is to: 392 393 <ol> 394 <li>keep the community informed about future changes to LLVM, </li> 395 396 <li>avoid duplication of effort by preventing multiple parties working on the 397 same thing and not knowing about it, and</li> 398 399 <li>ensure that any technical issues around the proposed work are discussed 400 and resolved before any significant work is done.</li> 401 </ol> 402 403 <p>The design of LLVM is carefully controlled to ensure that all the pieces fit 404 together well and are as consistent as possible. If you plan to make a major 405 change to the way LLVM works or want to add a major new extension, it is a 406 good idea to get consensus with the development community before you start 407 working on it.</p> 408 409 <p>Once the design of the new feature is finalized, the work itself should be 410 done as a series of <a href="#incremental">incremental changes</a>, not as a 411 long-term development branch.</p> 412 </div> 413 414 <!-- _______________________________________________________________________ --> 415 <h3><a name="incremental">Incremental Development</a></h3> 416 <div> 417 <p>In the LLVM project, we do all significant changes as a series of incremental 418 patches. We have a strong dislike for huge changes or long-term development 419 branches. Long-term development branches have a number of drawbacks:</p> 420 421 <ol> 422 <li>Branches must have mainline merged into them periodically. If the branch 423 development and mainline development occur in the same pieces of code, 424 resolving merge conflicts can take a lot of time.</li> 425 426 <li>Other people in the community tend to ignore work on branches.</li> 427 428 <li>Huge changes (produced when a branch is merged back onto mainline) are 429 extremely difficult to <a href="#reviews">code review</a>.</li> 430 431 <li>Branches are not routinely tested by our nightly tester 432 infrastructure.</li> 433 434 <li>Changes developed as monolithic large changes often don't work until the 435 entire set of changes is done. Breaking it down into a set of smaller 436 changes increases the odds that any of the work will be committed to the 437 main repository.</li> 438 </ol> 439 440 <p>To address these problems, LLVM uses an incremental development style and we 441 require contributors to follow this practice when making a large/invasive 442 change. Some tips:</p> 443 444 <ul> 445 <li>Large/invasive changes usually have a number of secondary changes that are 446 required before the big change can be made (e.g. API cleanup, etc). These 447 sorts of changes can often be done before the major change is done, 448 independently of that work.</li> 449 450 <li>The remaining inter-related work should be decomposed into unrelated sets 451 of changes if possible. Once this is done, define the first increment and 452 get consensus on what the end goal of the change is.</li> 453 454 <li>Each change in the set can be stand alone (e.g. to fix a bug), or part of 455 a planned series of changes that works towards the development goal.</li> 456 457 <li>Each change should be kept as small as possible. This simplifies your work 458 (into a logical progression), simplifies code review and reduces the 459 chance that you will get negative feedback on the change. Small increments 460 also facilitate the maintenance of a high quality code base.</li> 461 462 <li>Often, an independent precursor to a big change is to add a new API and 463 slowly migrate clients to use the new API. Each change to use the new API 464 is often "obvious" and can be committed without review. Once the new API 465 is in place and used, it is much easier to replace the underlying 466 implementation of the API. This implementation change is logically 467 separate from the API change.</li> 468 </ul> 469 470 <p>If you are interested in making a large change, and this scares you, please 471 make sure to first <a href="#newwork">discuss the change/gather consensus</a> 472 then ask about the best way to go about making the change.</p> 473 </div> 474 475 <!-- _______________________________________________________________________ --> 476 <h3><a name="attribution">Attribution of Changes</a></h3> 477 <div> 478 <p>We believe in correct attribution of contributions to their contributors. 479 However, we do not want the source code to be littered with random 480 attributions "this code written by J. Random Hacker" (this is noisy and 481 distracting). In practice, the revision control system keeps a perfect 482 history of who changed what, and the CREDITS.txt file describes higher-level 483 contributions. If you commit a patch for someone else, please say "patch 484 contributed by J. Random Hacker!" in the commit message.</p> 485 486 <p>Overall, please do not add contributor names to the source code.</p> 487 </div> 488 489 </div> 490 491 <!--=========================================================================--> 492 <h2> 493 <a name="clp">Copyright, License, and Patents</a> 494 </h2> 495 <!--=========================================================================--> 496 497 <div> 498 <p>This section addresses the issues of copyright, license and patents for the 499 LLVM project. The copyright holder for the code is held by the individual 500 contributors of the code and the terms of its license to LLVM users and 501 developers is the 502 <a href="http://www.opensource.org/licenses/UoI-NCSA.php">University of 503 Illinois/NCSA Open Source License</a>.</p> 504 505 <div class="doc_notes"> 506 <p style="text-align:center;font-weight:bold">NOTE: This section deals with 507 legal matters but does not provide legal advice. We are not lawyers, please 508 seek legal counsel from an attorney.</p> 509 </div> 510 511 <!-- _______________________________________________________________________ --> 512 <h3><a name="copyright">Copyright</a></h3> 513 <div> 514 515 <p>The LLVM project does not require copyright assignments, which means that the 516 copyright for the code in the project is held by its respective contributors 517 who have each agreed to release their contributed code under the terms of the 518 <a href="#license">LLVM License</a>.</p> 519 520 <p>An implication of this is that the LLVM license is unlikely to ever change: 521 changing it would require tracking down all the contributors to LLVM and 522 getting them to agree that a license change is acceptable for their 523 contribution. Since there are no plans to change the license, this is not a 524 cause for concern.</p> 525 526 <p>As a contributor to the project, this means that you (or your company) retain 527 ownership of the code you contribute, that it cannot be used in a way that 528 contradicts the license (which is a liberal BSD-style license), and that the 529 license for your contributions won't change without your approval in the 530 future.</p> 531 532 </div> 533 534 <!-- _______________________________________________________________________ --> 535 <h3><a name="license">License</a></h3> 536 <div> 537 <p>We intend to keep LLVM perpetually open source and to use a liberal open 538 source license. All of the code in LLVM is available under the 539 <a href="http://www.opensource.org/licenses/UoI-NCSA.php">University of 540 Illinois/NCSA Open Source License</a>, which boils down to this:</p> 541 542 <ul> 543 <li>You can freely distribute LLVM.</li> 544 <li>You must retain the copyright notice if you redistribute LLVM.</li> 545 <li>Binaries derived from LLVM must reproduce the copyright notice (e.g. in an 546 included readme file).</li> 547 <li>You can't use our names to promote your LLVM derived products.</li> 548 <li>There's no warranty on LLVM at all.</li> 549 </ul> 550 551 <p>We believe this fosters the widest adoption of LLVM because it <b>allows 552 commercial products to be derived from LLVM</b> with few restrictions and 553 without a requirement for making any derived works also open source (i.e. 554 LLVM's license is not a "copyleft" license like the GPL). We suggest that you 555 read the <a href="http://www.opensource.org/licenses/UoI-NCSA.php">License</a> 556 if further clarification is needed.</p> 557 558 <p>In addition to the UIUC license, the runtime library components of LLVM 559 (<b>compiler_rt and libc++</b>) are also licensed under the <a 560 href="http://www.opensource.org/licenses/mit-license.php">MIT license</a>, 561 which does not contain the binary redistribution clause. As a user of these 562 runtime libraries, it means that you can choose to use the code under either 563 license (and thus don't need the binary redistribution clause), and as a 564 contributor to the code that you agree that any contributions to these 565 libraries be licensed under both licenses. We feel that this is important 566 for runtime libraries, because they are implicitly linked into applications 567 and therefore should not subject those applications to the binary 568 redistribution clause. This also means that it is ok to move code from (e.g.) 569 libc++ to the LLVM core without concern, but that code cannot be moved from 570 the LLVM core to libc++ without the copyright owner's permission. 571 </p> 572 573 <p>Note that the LLVM Project does distribute llvm-gcc, <b>which is GPL.</b> 574 This means that anything "linked" into llvm-gcc must itself be compatible 575 with the GPL, and must be releasable under the terms of the GPL. This 576 implies that <b>any code linked into llvm-gcc and distributed to others may 577 be subject to the viral aspects of the GPL</b> (for example, a proprietary 578 code generator linked into llvm-gcc must be made available under the GPL). 579 This is not a problem for code already distributed under a more liberal 580 license (like the UIUC license), and does not affect code generated by 581 llvm-gcc. It may be a problem if you intend to base commercial development 582 on llvm-gcc without redistributing your source code.</p> 583 584 <p>We have no plans to change the license of LLVM. If you have questions or 585 comments about the license, please contact the 586 <a href="mailto:llvmdev (a] cs.uiuc.edu">LLVM Developer's Mailing List</a>.</p> 587 </div> 588 589 <!-- _______________________________________________________________________ --> 590 <h3><a name="patents">Patents</a></h3> 591 <div> 592 <p>To the best of our knowledge, LLVM does not infringe on any patents (we have 593 actually removed code from LLVM in the past that was found to infringe). 594 Having code in LLVM that infringes on patents would violate an important goal 595 of the project by making it hard or impossible to reuse the code for 596 arbitrary purposes (including commercial use).</p> 597 598 <p>When contributing code, we expect contributors to notify us of any potential 599 for patent-related trouble with their changes. If you or your employer own 600 the rights to a patent and would like to contribute code to LLVM that relies 601 on it, we require that the copyright owner sign an agreement that allows any 602 other user of LLVM to freely use your patent. Please contact 603 the <a href="mailto:llvm-oversight (a] cs.uiuc.edu">oversight group</a> for more 604 details.</p> 605 </div> 606 607 </div> 608 609 <!-- *********************************************************************** --> 610 <hr> 611 <address> 612 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img 613 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a> 614 <a href="http://validator.w3.org/check/referer"><img 615 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a> 616 Written by the 617 <a href="mailto:llvm-oversight (a] cs.uiuc.edu">LLVM Oversight Group</a><br> 618 <a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br> 619 Last modified: $Date: 2011-10-07 13:26:38 -0400 (Fri, 07 Oct 2011) $ 620 </address> 621 </body> 622 </html> 623
