Add LLVM realtime sanitizer #147935

luca3s · 2025-10-21T07:46:17Z

This is a new attempt at adding the LLVM real-time sanitizer to rust.

Previously this was attempted in rust-lang/rfcs#3766.

Since then the sanitize attribute was introduced in #142681 and it is a lot more flexible than the old no_santize attribute. This allows adding real-time sanitizer without the need for a new attribute, like it was proposed in the RFC. Because i only add a new value to a existing command line flag and to a attribute i don't think an MCP is necessary.

Currently real-time santizer is usable in rust code with the rtsan-standalone crate. This downloads or builds the sanitizer runtime and then links it into the rust binary.

The first commit adds support for more detailed sanitizer information.
The second commit then actually adds real-time sanitizer.
The third adds a warning against using real-time sanitizer with async functions, cloures and blocks because it doesn't behave as expected when used with async functions. I am not sure if this is actually wanted, so i kept it in a seperate commit.
The fourth commit adds the documentation for real-time sanitizer.

rustbot · 2025-10-21T07:46:20Z

compiletest directives have been modified. Please add or update docs for the
new or modified directive in src/doc/rustc-dev-guide/.

Some changes occurred in tests/ui/sanitizer

cc @rcvalle

Some changes occurred in src/tools/compiletest

cc @jieyouxu

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

Some changes occurred in compiler/rustc_hir/src/attrs

cc @jdonszelmann

These commits modify compiler targets.
(See the Target Tier Policy.)

Some changes occurred in src/doc/unstable-book/src/compiler-flags/sanitizer.md

cc @rust-lang/project-exploit-mitigations, @rcvalle

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann

This PR changes how LLVM is built. Consider updating src/bootstrap/download-ci-llvm-stamp.

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

The rustc-dev-guide subtree was changed. If this PR only touches the dev guide consider submitting a PR directly to rust-lang/rustc-dev-guide otherwise thank you for updating the dev guide with your changes.

cc @BoxyUwU, @jieyouxu, @Kobzol, @tshepang

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann

rustbot · 2025-10-21T07:46:23Z

r? @petrochenkov

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jdonszelmann · 2025-10-21T07:49:32Z

Looks ok from attr parsing pov :)

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

petrochenkov · 2025-10-21T12:29:00Z

This change has a lang component (marking functions a blocking or non-blocking), so I'll send this to lang team first, before reviewing the implementation in detail.

traviscross · 2025-10-22T17:38:16Z

Thanks for checking with us. We talked about this in the lang meeting today. We were OK with this going forward experimentally in nightly.

We talked about how, ahead of stabilization, we'd like to see the feature flags for the individual sanitizers be separate to facilitate our review, as we're likely to want to stabilize these incrementally.

Add LLVM realtime sanitizer This is a new attempt at adding the [LLVM real-time sanitizer](https://clang.llvm.org/docs/RealtimeSanitizer.html) to rust. Previously this was attempted in rust-lang/rfcs#3766. Since then the `sanitize` attribute was introduced in #142681 and it is a lot more flexible than the old `no_santize` attribute. This allows adding real-time sanitizer without the need for a new attribute, like it was proposed in the RFC. Because i only add a new value to a existing command line flag and to a attribute i don't think an MCP is necessary. Currently real-time santizer is usable in rust code with the [rtsan-standalone](https://crates.io/crates/rtsan-standalone) crate. This downloads or builds the sanitizer runtime and then links it into the rust binary. The first commit adds support for more detailed sanitizer information. The second commit then actually adds real-time sanitizer. The third adds a warning against using real-time sanitizer with async functions, cloures and blocks because it doesn't behave as expected when used with async functions. I am not sure if this is actually wanted, so i kept it in a seperate commit. The fourth commit adds the documentation for real-time sanitizer.

bors · 2025-10-31T14:55:19Z

⌛ Testing commit 8fb9389 with merge 88e2495...

luca3s · 2025-10-31T22:17:59Z

My bootstrap.toml was a bit weird and this in combination with a llvm update lead to x.py ignoring the rtsan tests. So i didn't notice that i used abort_on_error completely wrong. I tested (locally) with an aarch64-apple machine and tests ran and passed.

@rustbot ready

luca3s · 2025-11-01T11:18:12Z

This failure seems spurious. I've rebased to rerun the PR CI.

Zalathar · 2025-11-01T11:22:12Z

@bors try jobs=aarch64-apple,x86_64-gnu-llvm-20-3,test-various

Add LLVM realtime sanitizer try-job: aarch64-apple try-job: x86_64-gnu-llvm-20-3 try-job: test-various

rust-bors · 2025-11-01T14:00:37Z

☀️ Try build successful (CI)
Build commit: 63d0c9f (63d0c9f04594e3460660dd5f720ced531cbb5d08, parent: d85276b256a8ab18e03b6394b4f7a7b246176db7)

Rollup of 14 pull requests Successful merges: - rust-lang/rust#144936 (CFI: Fix types that implement Fn, FnMut, or FnOnce) - rust-lang/rust#147185 (repr(transparent): do not consider repr(C) types to be 1-ZST) - rust-lang/rust#147840 (Rework unsizing coercions in the new solver) - rust-lang/rust#147915 (Update target maintainers android.md) - rust-lang/rust#148013 (1.91.0 release notes) - rust-lang/rust#148044 (compiletest: show output in debug logging) - rust-lang/rust#148057 (tests/ui/sanitizer/hwaddress.rs: Run on aarch64 and remove cgu hack) - rust-lang/rust#148139 (Add `coverage` scope for controlling paths in code coverage) - rust-lang/rust#148154 (Add a mailmap entry) - rust-lang/rust#148158 (ci: loongarch64: use medium code model to avoid relocation overflows) - rust-lang/rust#148166 (Re-enable macro-stepping test for AArch64) - rust-lang/rust#148172 (rustc-dev-guide subtree update) - rust-lang/rust#148175 (Fix typos: duplicate words in comments) - rust-lang/rust#148186 (rustdoc-search: add an integration test for CCI) Failed merges: - rust-lang/rust#147935 (Add LLVM realtime sanitizer) r? `@ghost` `@rustbot` modify labels: rollup

rustbot · 2025-11-04T17:26:25Z

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

luca3s · 2025-11-04T17:31:51Z

Rustbot didn't show a conflict, but the github UI did and when rebasing i also had a (small) conflict.
Rebase diff is trivial.

petrochenkov · 2025-11-05T18:22:38Z

@bors r+

bors · 2025-11-05T18:22:42Z

📌 Commit 56aa047 has been approved by petrochenkov

It is now in the queue for this repository.

rustbot assigned petrochenkov Oct 21, 2025