Many aarch64 targets without LSE in the baseline enable the
`outline-atomics` feature, which uses runtime detection of LSE for its
faster atomic ops. This provides nontrivial performance improvements on
most hardware from the past decade, at a small cost to anything pre-LSE.
This matches what Clang does [1].
[1]:
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| .. | ||
| src | ||
| Cargo.toml | ||
| README.md | ||
rustc_target contains some very low-level details that are
specific to different compilation targets and so forth.
For more information about how rustc works, see the rustc dev guide.