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whitelist some ARM features #53926

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Sep 3, 2018
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whitelist some ARM features #53926

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4 changes: 4 additions & 0 deletions src/librustc_codegen_llvm/llvm_util.rs
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Expand Up @@ -86,10 +86,14 @@ unsafe fn configure_llvm(sess: &Session) {
// array, leading to crashes.

const ARM_WHITELIST: &[(&str, Option<&str>)] = &[
("aclass", Some("arm_target_feature")),
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As for mclass and rclass too, this should be renamed to a-profile before stabilisation. IMO it's better to do that now to avoid any unstable code using it to have to be changed.

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Also, before stabilization, neon on aarch64 should be renamed to asimd. @japaric it might be worth it to open an issue to track these on stdsimd, there might already be an issue open for the asimd rename task, so maybe this could be added to that one.

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Hmm, how does stabilization work for target_features? #[cfg(target_feature = "mclass")] is not feature gated on stable but it doesn't work. AFAICT that feature gate will work in the next beta which comes out in a week unless there's some "this is a nightly only feature" logic that I didn't see.

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@gnzlbg gnzlbg Sep 4, 2018 •
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Hmm, how does stabilization work for target_features?

In the RFC for the intrinsics, you write which target features they need, and that's pretty much it. We can stabilize them with the intrinsics.

AFAICT that feature gate will work in the next beta which comes out in a week unless there's some "this is a nightly only feature" logic that I didn't see.

Which feature gate? for example, the aclass above is gated on feature(arm_target_feature). Once arm_target_feature is stabilized, the aclass target feature will be usable on stable Rust.

Before stabilization we should split arm_target_feature features that we are not stabilizing into a new unstable feature.

("mclass", Some("arm_target_feature")),
("rclass", Some("arm_target_feature")),
("dsp", Some("arm_target_feature")),
("neon", Some("arm_target_feature")),
("v5te", Some("arm_target_feature")),
("v6k", Some("arm_target_feature")),
("v6t2", Some("arm_target_feature")),
("v7", Some("arm_target_feature")),
("vfp2", Some("arm_target_feature")),
("vfp3", Some("arm_target_feature")),
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