Enable `outline-atomics` by default on aarch64 platforms without LSE
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@yash-rana0101 is already working on this.
Since Feb 20, 2026.
A-target-feature
C-enhancement
E-help-wanted
E-medium
T-compiler
- Dominant language
- Rust
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- 119k
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Description
Since https://github.com/rust-lang/rust/pull/144938 and https://github.com/rust-lang/rust/pull/149633, most Aarch64 platforms that don't have LSE in the baseline enable the +outline-atomics target feature. We keep getting more targets that fall into this boat, however, so it's probably worth making this the default.
I think we can probably just unconditionally enable outline-atomics on all aarch64 targets without checking LSE, since LLVM should ignore it if +lse is also set/implied.
Note that Apple targets would need an explicit disable until https://github.com/rust-lang/rust/issues/149634 is fixed.
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