[docs] Add a section on AI-generated content to the developer policy (#91014)

Governments around the world are starting to require labelling for
AI-generated content, and some LLVM stakeholders have asked if LLVM
contains AI-generated content. Defining a policy on the use of AI tools
allows us to answer that question affirmatively, one way of the other.

The policy proposed here allows the use of AI tools in LLVM
contributions, flowing from the idea that any contribution is fine
regardless of how it is made, as long as the contributor has the right
to license it under the project license.

I gathered input from the community in this RFC and incorporated it into the policy:
https://discourse.llvm.org/t/rfc-define-policy-on-ai-tool-usage-in-contributions/78758

Author: rnk

llvm/docs/DeveloperPolicy.rst

@@ -1077,6 +1077,8 @@ If you have questions or comments about these topics, please ask on the
 please realize that most compiler developers are not lawyers, and therefore you
 will not be getting official legal advice.
 
+.. _LLVM Discourse forums: https://discourse.llvm.org
+
 Copyright
 ---------
 
@@ -1301,4 +1303,28 @@ to move code from (e.g.)  libc++ to the LLVM core without concern, but that code
 cannot be moved from the LLVM core to libc++ without the copyright owner's
 permission.
 
-.. _LLVM Discourse forums: https://discourse.llvm.org
+.. _ai contributions:
+
+AI generated contributions
+--------------------------
+
+Artificial intelligence systems raise many questions around copyright that have
+yet to be answered. Our policy on AI tools is guided by our copyright policy:
+Contributors are responsible for ensuring that they have the right to contribute
+code under the terms of our license, typically meaning that either they, their
+employer, or their collaborators hold the copyright. Using AI tools to
+regenerate copyrighted material does not remove the copyright, and contributors
+are responsible for ensuring that such material does not appear in their
+contributions.
+
+As such, the LLVM policy is that contributors are permitted to use artificial
+intelligence tools to produce contributions, provided that they have the right
+to license that code under the project license. Contributions found to violate
+this policy will be removed just like any other offending contribution.
+
+While the LLVM project has a liberal policy on AI tool use, contributors are
+considered responsible for their contributions. We encourage contributors to
+review all generated code before sending it for review to verify its
+correctness and to understand it so that they can answer questions during code
+review. Reviewing and maintaining generated code that the original contributor
+does not understand is not a good use of limited project resources.

llvm/docs/FAQ.rst

@@ -22,6 +22,13 @@ Yes. This is why we distribute LLVM under a less restrictive license than GPL,
 as explained in the first question above.
 
 
+Can I use AI coding tools, such as GitHub co-pilot, to write LLVM patches?
+--------------------------------------------------------------------------
+Yes, as long as the resulting work can be licensed under the project license, as
+covered in the :doc:`DeveloperPolicy`. Using an AI tool to reproduce copyrighted
+work does not rinse it of copyright and grant you the right to relicense it.
+
+
 Source Code
 ===========