compiler-builtins aarch64 outline atomics symbols do not work with BTI
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- Dominant language
- Rust
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Description
Continuing the discussion here as requested on https://github.com/rust-lang/rust/pull/144938
After this change, we're getting reports from developers about hitting SIGILL in Chromium's render process on some Android devices.
Disabling outline-atomics seems to fix the crashes.
We don't have a good understanding of the root cause yet, but for a start, we'd like to be able to disable the feature.
Passing -Ctarget-feature=-outline-atomics works, but causes warnings:
warning: unstable feature specified for `-Ctarget-feature`: `outline-atomics`
|
= note: this feature is not stably supported; its behavior can change in the future
It would be good to have a knob for turning off the feature without warnings. Alternatively it would be good to have a knob to turn off that kind of warning.
(We'll hack it out for now: https://github.com/zmodem/rust/commit/b01caa5309eb7d47bbd2a0b4ae63f7d065be1963)
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Read PR #144938 and its discussion first, then trace how Rust handles the outline-atomics target feature and its unstable-feature warning. Done means providing a supported way to disable outline-atomics without that warning, or a supported way to suppress this warning, while addressing the reported aarch64 BTI context.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- compilers
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100