Rust Project Goals

The 2025h2 goal period is over, closing...

The 2025h2 goal period is now over, so I'm closing this issue. Thanks to everyone who contributed! The BorrowSanitizer goal will continue this work in the 2026 period. Authors are welcome to leave a final comment about the goal's outcome.

We have some exciting news: our talk on BorrowSanitizer was accepted at RustConf this year! We’re grateful for the opportunity and looking forward to sharing our results with the broader community this September.

We just posted our April status update. It’s a bit of a technical one. Here’s the TL;DR:

• BorrowSanitizer now uses a shadow stack to track metadata at runtime - this is a significantly different strategy than other LLVM sanitizers, and it will help us support garbage collection.

• We are now ready to start sending in PRs for our retag intrinsics. It will take a little time to split our changes up into meaningful, reviewable chunks—you can expect to see these throughout the next week.

The RFC for our LLVM components is taking a little longer than expected, but it was worth taking the extra time to test out compiler changes and make sure that we had the core parts of the instrumentation pass settled. We’ll be drafting the RFC throughout the next few weeks.

We just posted our March status update for BorrowSanitizer. TL;DR:

• We added hundreds more relevant tests from Miri's test suite. At the moment, 80% pass.
• We improved our cargo plugin (cargo-bsan) to better support multilanguage libraries. This will let us start to recreate the bugs from our earlier evaluation.

Our goal for April is to continue expanding our test suite, finish an initial version of the LLVM components of BorrowSanitizer, and hopefully start the RFC process on the LLVM side.

The 2025h2 goal period is now over, so I'm closing this issue. Thanks to everyone who contributed! The High-Level ML optimizations goal will build on this work in the 2026 period. Authors are welcome to leave a final comment about the goal's outcome.

Key developments:

std::autodiff is now partly in CI, and std::offload got tested on a lot more benchmarks.

autodiff

Work continued on enabling autodiff in nightly. Since the last update, we have enabled autodiff in some Mingw and Linux runners. Users can now download libEnzyme artifacts, place them locally in the right spot for their toolchain, and then use autodiff on their nightly compiler. Once macOS is added, we will enable a new rustup component that will handle the download for users. Before enabling autodiff on macOS, however, we want to change how we distribute LLVM on this target (from static to dynamic linking). There are a lot of workflows and users of this target, not all of which can be modelled in the Rust CI. Our last two attempts sadly broke such downstream users and local contributors, so both attempts had to be reverted. Since testing here is tricky, progress here might be on the slower side; we will see.

offload

Most of the work on the offload side lately has been invisible, since we were working on implementing more benchmarks and LLVM optimizations, as well as missing features, discovered by those benchmarks. We achieved excellent performance on those benchmarks; more details will soon be presented by Marcelo Domínguez at the EuroLLVM conference in two weeks!

Beyond benchmarks, there was a lot of tinkering on smaller PRs, reviewing, and housekeeping. LLVM-22 landed, so we updated our bootrstrap code to make use of new APIs, and tried to move a few smaller PRs forward, mainly around a better user experience and for making more Rust features available. Since the focus is still on benchmarks, not many of those PRs landed. They are in a mostly ready state, so it's a good time to pick them up if you're considering contributing. Please ping me on Zulip or in any PR with the offload label if you are interested!

The 2025h2 goal period is now over, so I'm closing this issue. Thanks to everyone who contributed! Authors are welcome to leave a final comment about the goal's outcome.