rust-lang / rust-lang/rust

Enable `outline-atomics` by default on aarch64 Apple targets

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#149,634 12 comments 1 reaction 0 assignees View on GitHub

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A-compiler-builtins A-LLVM O-apple T-compiler
Dominant language
Rust
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Description

This was originally part of https://github.com/rust-lang/rust/pull/144938, but per https://github.com/rust-lang/rust/pull/144938#pullrequestreview-3208320060 this does not seem to work correctly. Seems like there may be some behavior to clarify with LLVM, or a possible bug there.

This does not affect Darwin or *-sim since LSE is already in the baseline. I have a branch enabling things here https://github.com/tgross35/rust/commit/apple-outline-atomics/.

cc @madsmtm

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading pull request 144938 and its review discussion, then inspect the apple-outline-atomics branch linked in the issue. Clarify the LLVM behavior affecting aarch64 Apple targets, excluding Darwin and *-sim, and verify that enabling outline-atomics by default works correctly for the remaining targets.

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
Quiet
Clarity
Mostly clear
Newbie friendliness
38/100

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