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specify s390x target features #1972

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specify s390x target features
folkertdev Aug 20, 2025
4ec04bc
Revise `s390x` codegen text
traviscross Aug 20, 2025
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27 changes: 25 additions & 2 deletions src/attributes/codegen.md
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Expand Up @@ -506,6 +506,30 @@ Feature | Implicitly Enables | Description
[tail-call]: https://github.com/webassembly/tail-call
[multivalue]: https://github.com/webassembly/multi-value

r[attributes.codegen.target_feature.s390x]
#### `s390x`

On `s390x` targets, use of functions with the `#[target_feature]` attribute follows the [above restrictions][attributes.codegen.target_feature.safety-restrictions].

Further documentation on these features can be found in the "Additions to z/Architecture" section of Chapter 1 of the *[z/Architecture Principles of Operation]*.

Feature | Implicitly Enables | Description
---------------------------------------|---------------------------------------|---------------------
`vector` | | 128-bit vector instructions
`vector-enhancements-1` | `vector` | vector enhancements 1
`vector-enhancements-2` | `vector-enhancements-1` | vector enhancements 2
`vector-enhancements-3` | `vector-enhancements-2` | vector enhancements 3
`vector-packed-decimal` | `vector` | vector packed-decimal
`vector-packed-decimal-enhancement` | `vector-packed-decimal` | vector packed-decimal enhancement
`vector-packed-decimal-enhancement-2` | `vector-packed-decimal-enhancement-2` | vector packed-decimal enhancement 2
`vector-packed-decimal-enhancement-3` | `vector-packed-decimal-enhancement-3` | vector packed-decimal enhancement 3
`nnp-assist` | `vector` | nnp assist
`miscellaneous-extensions-2` | | miscellaneous extensions 2
`miscellaneous-extensions-3` | | miscellaneous extensions 3
`miscellaneous-extensions-4` | | miscellaneous extensions 4

[z/Architecture Principles of Operation]: https://publibfp.dhe.ibm.com/epubs/pdf/a227832d.pdf

r[attributes.codegen.target_feature.info]
### Additional information

Expand All @@ -516,8 +540,7 @@ that this option is not affected by the `target_feature` attribute, and is
only driven by the features enabled for the entire crate.

r[attributes.codegen.target_feature.remark-rt]
See the [`is_x86_feature_detected`] or [`is_aarch64_feature_detected`] macros
in the standard library for runtime feature detection on these platforms.
Whether a feature is enabled can be checked at runtime using a platform-specific macro from the standard library, for instance [`is_x86_feature_detected`] or [`is_aarch64_feature_detected`].

> [!NOTE]
> `rustc` has a default set of features enabled for each target and CPU. The CPU may be chosen with the [`-C target-cpu`] flag. Individual features may be enabled or disabled for an entire crate with the [`-C target-feature`] flag.
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