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Update list of allowed aarch64 features #84665

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merged 5 commits into from
May 20, 2021
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Merged

Update list of allowed aarch64 features #84665

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3f5f54c
Update list of allowed aarch64 features
adamgemmell Apr 28, 2021
523b4d1
Remove LSE2
adamgemmell May 19, 2021
c71e58d
Rename fptoint to frintts
adamgemmell May 19, 2021
904467a
Ensure all crypto components (AES, PMULL, SHA1/2) are available on ar…
adamgemmell May 19, 2021
d3737a6
Remove test for crypto feature ahead of its removal
adamgemmell May 19, 2021
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6 changes: 6 additions & 0 deletions compiler/rustc_codegen_llvm/src/llvm_util.rs
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Original file line number Diff line number Diff line change
@@ -152,6 +152,12 @@ pub fn to_llvm_feature<'a>(sess: &Session, s: &'a str) -> &'a str {
("x86", "avx512vpclmulqdq") => "vpclmulqdq",
("aarch64", "fp") => "fp-armv8",
("aarch64", "fp16") => "fullfp16",
("aarch64", "fhm") => "fp16fml",
("aarch64", "lse2") => "outline-atomics",
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lse2 doesn't have an LLVM equivalent feature: it doesn't add any new instructions, it just relaxes the restrictions on existing atomic instructions.

outline-atomics is something different: it's a codegen option on LLVM to call external functions for atomic operations so that they can take advantage of LSE on targets that support it.

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Nice catch, thanks a lot!

("aarch64", "rcpc2") => "rcpc-immo",
("aarch64", "dpb") => "ccpp",
("aarch64", "dpb2") => "ccdp",
("aarch64", "fcma") => "complxnum",
(_, s) => s,
}
}
77 changes: 75 additions & 2 deletions compiler/rustc_codegen_ssa/src/target_features.rs
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Original file line number Diff line number Diff line change
@@ -33,22 +33,95 @@ const ARM_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
("thumb-mode", Some(sym::arm_target_feature)),
];

// Commented features are not available in LLVM 9.0, or have since been renamed
const AARCH64_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
("fp", Some(sym::aarch64_target_feature)),
// FEAT_AdvSimd
("neon", Some(sym::aarch64_target_feature)),
// FEAT_FP
("fp", Some(sym::aarch64_target_feature)),
// FEAT_FP16
("fp16", Some(sym::aarch64_target_feature)),
// FEAT_SVE
("sve", Some(sym::aarch64_target_feature)),
// FEAT_CRC
("crc", Some(sym::aarch64_target_feature)),
// Cryptographic extension
("crypto", Some(sym::aarch64_target_feature)),
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LLVM has moved away from a combined "crypto" feature and now uses separate "aes" and "sha2" features. We should do the same here.

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I agree - the crypto feature doesn't really mean much any more and the separate features are better. Wouldn't removing this here affect any users detecting this feature? Likewise with removing it from std_detect.

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AArch64 target features are still unstable, so it's fine to rename/remove them.

// FEAT_RAS
("ras", Some(sym::aarch64_target_feature)),
// FEAT_LSE
("lse", Some(sym::aarch64_target_feature)),
// FEAT_LSE2
// ("lse2", Some(sym::aarch64_target_feature)),
// FEAT_RDM
("rdm", Some(sym::aarch64_target_feature)),
("fp16", Some(sym::aarch64_target_feature)),
// FEAT_RCPC
("rcpc", Some(sym::aarch64_target_feature)),
// FEAT_RCPC2
("rcpc2", Some(sym::aarch64_target_feature)),
// FEAT_DotProd
("dotprod", Some(sym::aarch64_target_feature)),
// FEAT_TME
("tme", Some(sym::aarch64_target_feature)),
// FEAT_FHM
("fhm", Some(sym::aarch64_target_feature)),
// FEAT_DIT
("dit", Some(sym::aarch64_target_feature)),
// FEAT_FLAGM
// ("flagm", Some(sym::aarch64_target_feature)),
// FEAT_SSBS
("ssbs", Some(sym::aarch64_target_feature)),
// FEAT_SB
("sb", Some(sym::aarch64_target_feature)),
// FEAT_PAUTH
// ("pauth", Some(sym::aarch64_target_feature)),
// FEAT_DPB
("dpb", Some(sym::aarch64_target_feature)),
// FEAT_DPB2
("dpb2", Some(sym::aarch64_target_feature)),
// FEAT_SVE2
("sve2", Some(sym::aarch64_target_feature)),
// FEAT_SVE2_AES
("sve2-aes", Some(sym::aarch64_target_feature)),
// FEAT_SVE2_SM4
("sve2-sm4", Some(sym::aarch64_target_feature)),
// FEAT_SVE2_SHA3
("sve2-sha3", Some(sym::aarch64_target_feature)),
// FEAT_SVE2_BitPerm
("sve2-bitperm", Some(sym::aarch64_target_feature)),
// FEAT_FRINTTS
("fptoint", Some(sym::aarch64_target_feature)),
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"fptoint" is a poor name for this feature, I prefer the original ARM name "frintts".

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Happy to rename this

// FEAT_I8MM
// ("i8mm", Some(sym::aarch64_target_feature)),
// FEAT_F32MM
// ("f32mm", Some(sym::aarch64_target_feature)),
// FEAT_F64MM
// ("f64mm", Some(sym::aarch64_target_feature)),
// FEAT_BF16
// ("bf16", Some(sym::aarch64_target_feature)),
// FEAT_RAND
("rand", Some(sym::aarch64_target_feature)),
// FEAT_BTI
("bti", Some(sym::aarch64_target_feature)),
// FEAT_MTE
("mte", Some(sym::aarch64_target_feature)),
// FEAT_JSCVT
("jsconv", Some(sym::aarch64_target_feature)),
// FEAT_FCMA
("fcma", Some(sym::aarch64_target_feature)),
// FEAT_SHA1 & FEAT_SHA256
("sha2", Some(sym::aarch64_target_feature)),
// FEAT_SHA512 & FEAT_SHA3
("sha3", Some(sym::aarch64_target_feature)),
// FEAT_SM3 & FEAT_SM4
("sm4", Some(sym::aarch64_target_feature)),
("v8.1a", Some(sym::aarch64_target_feature)),
("v8.2a", Some(sym::aarch64_target_feature)),
("v8.3a", Some(sym::aarch64_target_feature)),
("v8.4a", Some(sym::aarch64_target_feature)),
("v8.5a", Some(sym::aarch64_target_feature)),
// ("v8.6a", Some(sym::aarch64_target_feature)),
// ("v8.7a", Some(sym::aarch64_target_feature)),
];

const X86_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[