LLVM has a code review policy. Code review is an excellent way to ensure high quality in the software. The following policies apply:

1. All developers are required to have significant changes reviewed before they are committed to the repository.
2. Code reviews are conducted by email.
3. Code can be reviewed either before it is committed or after.
4. The developer responsible for a code change is also responsible for making all necessary review changes.
5. Developers should participate in code reviews as both a reviewer and a reviewee. We don't have a dedicated team of reviewers. If someone is kind enough to review your code, you should return the favor for someone else.

LLVM uses an incremental development style and all developers are expected to follow this practice. Incremental development is a big key to LLVM's success and it is essential that developers submit incremental patches. The following defines the incremental development approach:

1. The first task is to define the increment and get consensus (with the LLVM development community) on what the end goal of the change is. Making random small changes that go nowhere is not useful for anyone.
2. An increment is the smallest patch size necessary to effect one change in LLVM.
3. Increments can be stand alone (e.g. to fix a bug), or part of a planned series of increments towards some development goal.
4. Increments should be kept as small as possible. This simplifies your work (into a logical progression), simplifies code review and reduces the chance that you will get negative feedback on the change. Small increments also facilitate the maintenance of a high quality code base.
5. Larger increments require a larger testing effort.

The minimum quality standards for any change to the main development branch are:

1. Code must adhere to the LLVM Coding Standards.
2. Code must compile cleanly (no errors, no warnings) on at least one platform.
3. Code must pass the deja gnu (llvm/test) test suite.

Additionally, the committer is responsible for addressing all of the following items (preferably before submission):

1. The code should compile cleanly on all platforms.
2. The changes should not cause regressions in the llvm-test suite including SPEC CINT2000, SPEC CFP2000, SPEC CINT2006, and SPEC CFP2006.
3. The change set should not cause performance or correctness regressions for the LLVM tools.
4. The changes should not cause performance or correctness regressions in code compiled by LLVM on all applicable targets.

Developers are required to create test cases for regressions and new features and include them with their changes. The following policies apply:

1. All feature and regression test cases must be added to the llvm/test directory. The appropriate sub-directory should be selected (see the Testing Guide for details).
2. Test cases should be written in LLVM assembly language unless the feature or regression being tested requires another language (e.g. the bug being fixed or feature being implemented is in the lvm-gcc C++ front-end).
3. Test cases, especially for regressions, should be reduced as much as possible, by bugpoint or manually. It is unacceptable to place an entire failing program into llvm/test as this creates a time-to-test burden on all developers. Please keep them short.
4. More extensive test cases (applications, benchmarks, etc.) should be added to the llvm-test test suite. This test suite is for coverage not features or regressions.

This section contains policies that pertain to submitting patches to LLVM and committing code to the repository

When submitting a patch, developers must follow these rules:

1. Patches must be made against the CVS HEAD (main development trunk), not a branch.
2. Patches should be made with this command:

       cvs diff -Ntdup -5

   or with the utility utils/mkpatch.
3. Patches should not include differences in generated code such as the code generated by flex, bison or tblgen. The utils/mkpatch utility takes care of this for you.
4. Patches must not include any patent violations. To the best of our knowledge, LLVM is free of any existing patent violations and it is our intent to keep it that way.

Before a patch is submitted for review, it should be tested to ensure that:

1. The patch must compile against the CVS HEAD cleanly (zero warnings, zero errors).
2. All the llvm/test (Deja Gnu) tests must pass.
3. The patch should cause no regressions in the llvm-test test suite. How much testing is appropriate depends on the nature of the patch. We leave it to your good judgement, but you will be responsible for fixing any regressions or reverting the patch.

When a patch is ready to be submitted, these policies apply:

1. Patches should be submitted immediately after they are generated. Stale patches may not apply correctly if the underlying code changes between the time the patch was created and the time it is applied.
2. Patches should be submitted by e-mail to the llvm-commits list.

After a patch has been submitted, these policies apply:

1. The patch is subject to review by anyone on the llvm-commits email list.
2. Changes recommended by a reviewer should be incorporated into your patch or you should explain why the reviewer is incorrect.
3. Changes to the patch must be re-submitted to the llvm-commits email list.
4. This process iterates until all review issues have been addressed.

After a patch has been committed, these policies apply:

1. The patch is subject to further review by anyone on the llvm-commits email list.
2. The patch submitter is responsible for all aspects of the patch per the quality policy above.
3. If the patch is discovered to not meet the quality policy standards within a reasonable time frame (24 hours), it may be subject to reversal.

Commit access to the repository is granted according to this policy:

1. Commit access is not granted to anyone unless they specifically ask for it.
2. Requests for commit access must be sent to the LLVM Oversight Group.
3. Granting commit access is at the sole discretion of the LLVM Oversight Group.

Submitting patches to LLVM via the patch policy above will greatly increase the chance that your request for commit access is granted. Getting to know the members of the LLVM community (email, IRC, in person contact, etc.) will also increase your chances.

For those who have recently obtained commit access, the following policies apply:

1. You are granted commit-after-approval to all parts of LLVM. To get approval, submit a patch to llvm-commits per the patch policies above. When approved you may commit it yourself.
2. You are allowed to commit patches without approval which you think are obvious. This is clearly a subjective decision. We simply expect you to use good judgement.
3. You are allowed to commit patches without approval to those portions of LLVM that you own (contributed) or maintain (have been assigned responsibility for), with the proviso that such commits must not break the build. This is a "trust but verify" policy and commits of this nature are reviewed after they are committed.
4. Commits that violate the quality standards may be reverted. This is necessary when the change blocks other developers from making progress. The developer is welcome to re-commit the change after the problem has been fixed.
5. Multiple violations of these policies or a single egregious violation may cause commit access to be revoked.

We address here the issues of copyright and license for the LLVM project. The object of the copyright and license is the LLVM source code and documentation. Currently, the University of Illinois is the LLVM copyright holder and the terms of its license to LLVM users and developers is the University of Illinois/NCSA Open Source License.

The LLVM project believes in correct attribution of contributions to their contributors, as follows:

1. Developers who originate new files in LLVM should place their name at the top of the file per the Coding Standards.
2. There should be only one name at the top of the file and it should be the person who created the file.
3. Placing your name in the file does not imply copyright but does correctly attribute the file to its author.
4. Developers should be aware that after some time has passed, the name at the top of a file may become meaningless as maintenance/ownership of files changes.
5. Developers should submit or commit patches to the CREDITS.txt file to summarize their contributions.
6. Commit comments should contain correct attribution of the person who submitted the patch if that person is not the committer (i.e. when a developer with commit privileges commits a patch for someone else).

For consistency and ease of management, the project requires the copyright for all LLVM software to be held by a single copyright holder. Although UIUC may assign the copyright of the software to another entity, the intent for the project is to always have a single entity hold the copy rights to LLVM at any given time.

Having multiple copyright holders for various portions of LLVM is problematic in the management of the software. Having a single copyright holder is in the best interests of all developers and users as it greatly reduces the managerial burden for any kind of administrative or technical decisions about LLVM.

LLVM licensing decisions will be made by the LLVM Oversight Group. Any issues, comments or suggestions with the licensing should be sent to the LLVM Oversight Group.

The LLVM Oversight Group intends to keep LLVM perpetually open source and to use liberal open source licenses. The current license is the University of Illinois/NCSA Open Source License, which boils down to this:

• You can freely distribute LLVM.
• You must retain the copyright notice if you redistribute LLVM.
• Binaries derived from LLVM must reproduce the copyright notice.
• You can't use our names to promote your LLVM derived products.
• There's no warranty on LLVM at all.

We believe this fosters the widest adoption of LLVM because it allows commercial products to be derived from LLVM with few restrictions and without a requirement for making any derived works also open source (i.e. LLVM's license is not a copyleft license). We suggest that you read the License if further clarification is needed.

With regards to the LLVM copyright and licensing, developers agree to:

• assign their copy rights to UIUC for any contribution made so that the entire software base can be managed by a single copyright holder.
• allow their contribution(s) to be licensed as open source by the then current license chosen by the LLVM Oversight Group.

So that the policies defined in this document are clear, we define some terms here.

Change

Any modification to LLVM including documentation, tests, build system, etc. either in patch or commit form.

Commit

A change submitted directly to LLVM software repository via the cvs commit command.

Copyleft

A licensing policy that requires the licensee to adopt the terms of the license for derived works. LLVM does not subscribe to this policy.

Developer

Anyone who submits a change to LLVM.

Increment

A change or set of changes, whether by patch or commit, that are related by a single common purpose. Increments are atomic as they leave LLVM in a stable state (both compiling and working properly).

Must

When used in a policy statement, the term must implies a non-optional requirement on the developer.

Patch

A change submitted by email in patch (diff) format generated by the cvs diff command.

Should

When used in a policy statement, the term should implies a recommended but optional requirement on the developer.

This section contains some notes on policy topics that need to be resolved and incorporated into the main body of the document above.

1. When to open a new bug and when to re-use an existing one. For example PR1158. If the same assertion happens do you open a new bug or reopen 1158?