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.

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.

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 · 2025-11-06T00:15:58Z

⌛ Testing commit 56aa047 with merge 331ae1d...

bors · 2025-11-06T01:48:44Z

💔 Test failed - checks-actions

Zalathar · 2025-11-06T01:53:34Z

Failure in rustdoc-gui looks bogus.

@bors retry

Rollup of 7 pull requests Successful merges: - #143037 (Make named asm_labels lint not trigger on hexagon register spans) - #147043 (Add default sanitizers to TargetOptions) - #147586 (std-detect: improve detect macro docs) - #147912 ([rustdoc] Gracefully handle error in case we cannot run the compiler in doctests) - #148540 (Minor fixes to StdNonZeroNumberProvider for gdb) - #148541 (Add num_children method to some gdb pretty-printers) - #148549 (Fix broken qemu-cskyv2 link) Failed merges: - #147935 (Add LLVM realtime sanitizer) r? `@ghost` `@rustbot` modify labels: rollup

Zalathar · 2025-11-06T11:54:58Z

Unfortunately this now has another conflict.

@bors r-

rustbot · 2025-11-06T12:27:08Z

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 · 2025-11-06T12:30:17Z

@rustbot ready

rustbot assigned petrochenkov Oct 21, 2025