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+# Contributing to `packed_simd`
+
+Welcome! If you are reading this document, it means you are interested in contributing
+to the `packed_simd` crate.
+
+## Reporting issues
+
+All issues with this crate are tracked using GitHub's [Issue Tracker].
+
+You can use issues to bring bugs to the attention of the maintainers, to discuss
+certain problems encountered with the crate, or to request new features (although
+feature requests should be limited to things mentioned in the [RFC]).
+
+One thing to keep in mind is to always use the **latest** nightly toolchain when
+working on this crate. Due to the nature of this project, we use a lot of unstable
+features, meaning breakage happens often.
+
+[Issue Tracker]: https://github.com/rust-lang-nursery/packed_simd/issues
+[RFC]: https://github.com/rust-lang/rfcs/pull/2366
+
+### LLVM issues
+
+The Rust compiler relies on [LLVM](https://llvm.org/) for machine code generation,
+and quite a few LLVM bugs have been discovered during the development of this project.
+
+If you encounter issues with incorrect/suboptimal codegen, which you do not encounter
+when using the [SIMD vendor intrinsics](https://doc.rust-lang.org/nightly/std/arch/),
+it is likely the issue is with LLVM, or this crate's interaction with it.
+
+You should first open an issue **in this repo** to help us track the problem, and we
+will help determine what is the exact cause of the problem.
+If LLVM is indeed the cause, the issue will be reported upstream to the
+[LLVM bugtracker](https://bugs.llvm.org/).
+
+## Submitting Pull Requests
+
+New code is submitted to the crate using GitHub's [pull request] mechanism.
+You should first fork this repository, make your changes (preferably in a new
+branch), then use GitHub's web UI to create a new PR.
+
+[pull request]: https://help.github.com/articles/about-pull-requests/
+
+### Examples
+
+The `examples` directory contains code showcasing SIMD code written with this crate,
+usually in comparison to scalar or ISPC code. If you have a project / idea which
+uses SIMD, we'd love to add it to the examples list.
+
+Every example should include a small `README`, describing the example code's purpose.
+If your example could potentially work as a benchmark, then add a `benchmark.sh`
+script to allow running the example benchmark code in CI. See an existing example's
+[`benchmark.sh`](examples/aobench/benchmark.sh) for a sample.
+
+Don't forget to update the crate's top-level `README` with a link to your example.
+
+### Perf guide
+
+The objective of the [performance guide][perf-guide] is to be a comprehensive
+resource detailing the process of optimizing Rust code with SIMD support.
+
+If you believe a certain section could be reworded, or if you have any tips & tricks
+related to SIMD which you'd like to share, please open a PR.
+
+[mdBook] is used to manage the formatting of the guide as a book.
+
+[perf-guide]: https://rust-lang-nursery.github.io/packed_simd/perf-guide/
+[mdBook]: https://github.com/rust-lang-nursery/mdBook