rustc_target: Add various aarch64 features

Add various aarch64 features already supported by LLVM and Linux.

The features are marked as unstable using a newly added symbol, i.e.
aarch64_unstable_target_feature.

Additionally include some comment fixes to ensure consistency of
feature names with the Arm ARM and support for architecture version
target features up to v9.5a.

This commit adds compiler support for the following features:

- FEAT_CSSC
- FEAT_ECV
- FEAT_FAMINMAX
- FEAT_FLAGM2
- FEAT_FP8
- FEAT_FP8DOT2
- FEAT_FP8DOT4
- FEAT_FP8FMA
- FEAT_FPMR
- FEAT_HBC
- FEAT_LSE128
- FEAT_LSE2
- FEAT_LUT
- FEAT_MOPS
- FEAT_LRCPC3
- FEAT_SVE_B16B16
- FEAT_SVE2p1
- FEAT_WFxT

4 files changed, 53 insertions, 5 deletions

diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 7af5eb9278f..a0ef6483ed6 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -234,6 +234,8 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> LLVMFeature<'a
         ("aarch64", "pmuv3") => LLVMFeature::new("perfmon"),
         ("aarch64", "paca") => LLVMFeature::new("pauth"),
         ("aarch64", "pacg") => LLVMFeature::new("pauth"),
+        ("aarch64", "sve-b16b16") => LLVMFeature::new("b16b16"),
+        ("aarch64", "flagm2") => LLVMFeature::new("altnzcv"),
         // Rust ties fp and neon together.
         ("aarch64", "neon") => {
             LLVMFeature::with_dependency("neon", TargetFeatureFoldStrength::Both("fp-armv8"))
diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs
index 4524458023d..1ec1990d2c5 100644
--- a/compiler/rustc_feature/src/unstable.rs
+++ b/compiler/rustc_feature/src/unstable.rs
@@ -302,6 +302,7 @@ declare_features! (
     // FIXME: Document these and merge with the list below.
 
     // Unstable `#[target_feature]` directives.
+    (unstable, aarch64_unstable_target_feature, "CURRENT_RUSTC_VERSION", Some(44839)),
     (unstable, aarch64_ver_target_feature, "1.27.0", Some(44839)),
     (unstable, arm_target_feature, "1.27.0", Some(44839)),
     (unstable, avx512_target_feature, "1.27.0", Some(44839)),
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 2957105288b..e691d1cfcb5 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -356,6 +356,7 @@ symbols! {
         _task_context,
         a32,
         aarch64_target_feature,
+        aarch64_unstable_target_feature,
         aarch64_ver_target_feature,
         abi,
         abi_amdgpu_kernel,
diff --git a/compiler/rustc_target/src/target_features.rs b/compiler/rustc_target/src/target_features.rs
index da66ba270b3..d4b5a5ff675 100644
--- a/compiler/rustc_target/src/target_features.rs
+++ b/compiler/rustc_target/src/target_features.rs
@@ -99,6 +99,8 @@ const AARCH64_ALLOWED_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ("bti", Stable, &[]),
     // FEAT_CRC
     ("crc", Stable, &[]),
+    // FEAT_CSSC
+    ("cssc", Unstable(sym::aarch64_unstable_target_feature), &[]),
     // FEAT_DIT
     ("dit", Stable, &[]),
     // FEAT_DotProd
@@ -107,21 +109,39 @@ const AARCH64_ALLOWED_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ("dpb", Stable, &[]),
     // FEAT_DPB2
     ("dpb2", Stable, &["dpb"]),
+    // FEAT_ECV
+    ("ecv", Unstable(sym::aarch64_unstable_target_feature), &[]),
     // FEAT_F32MM
     ("f32mm", Stable, &["sve"]),
     // FEAT_F64MM
     ("f64mm", Stable, &["sve"]),
+    // FEAT_FAMINMAX
+    ("faminmax", Unstable(sym::aarch64_unstable_target_feature), &[]),
     // FEAT_FCMA
     ("fcma", Stable, &["neon"]),
     // FEAT_FHM
     ("fhm", Stable, &["fp16"]),
     // FEAT_FLAGM
     ("flagm", Stable, &[]),
+    // FEAT_FLAGM2
+    ("flagm2", Unstable(sym::aarch64_unstable_target_feature), &[]),
     // FEAT_FP16
     // Rust ties FP and Neon: https://github.com/rust-lang/rust/pull/91608
     ("fp16", Stable, &["neon"]),
+    // FEAT_FP8
+    ("fp8", Unstable(sym::aarch64_unstable_target_feature), &["faminmax", "lut", "bf16"]),
+    // FEAT_FP8DOT2
+    ("fp8dot2", Unstable(sym::aarch64_unstable_target_feature), &["fp8dot4"]),
+    // FEAT_FP8DOT4
+    ("fp8dot4", Unstable(sym::aarch64_unstable_target_feature), &["fp8fma"]),
+    // FEAT_FP8FMA
+    ("fp8fma", Unstable(sym::aarch64_unstable_target_feature), &["fp8"]),
+    // FEAT_FPMR
+    ("fpmr", Unstable(sym::aarch64_unstable_target_feature), &[]),
     // FEAT_FRINTTS
     ("frintts", Stable, &[]),
+    // FEAT_HBC
+    ("hbc", Unstable(sym::aarch64_unstable_target_feature), &[]),
     // FEAT_I8MM
     ("i8mm", Stable, &[]),
     // FEAT_JSCVT
@@ -131,6 +151,14 @@ const AARCH64_ALLOWED_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ("lor", Stable, &[]),
     // FEAT_LSE
     ("lse", Stable, &[]),
+    // FEAT_LSE128
+    ("lse128", Unstable(sym::aarch64_unstable_target_feature), &["lse"]),
+    // FEAT_LSE2
+    ("lse2", Unstable(sym::aarch64_unstable_target_feature), &[]),
+    // FEAT_LUT
+    ("lut", Unstable(sym::aarch64_unstable_target_feature), &[]),
+    // FEAT_MOPS
+    ("mops", Unstable(sym::aarch64_unstable_target_feature), &[]),
     // FEAT_MTE & FEAT_MTE2
     ("mte", Stable, &[]),
     // FEAT_AdvSimd & FEAT_FP
@@ -143,14 +171,16 @@ const AARCH64_ALLOWED_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ("pan", Stable, &[]),
     // FEAT_PMUv3
     ("pmuv3", Stable, &[]),
-    // FEAT_RAND
+    // FEAT_RNG
     ("rand", Stable, &[]),
     // FEAT_RAS & FEAT_RASv1p1
     ("ras", Stable, &[]),
-    // FEAT_RCPC
+    // FEAT_LRCPC
     ("rcpc", Stable, &[]),
-    // FEAT_RCPC2
+    // FEAT_LRCPC2
     ("rcpc2", Stable, &["rcpc"]),
+    // FEAT_LRCPC3
+    ("rcpc3", Unstable(sym::aarch64_unstable_target_feature), &["rcpc2"]),
     // FEAT_RDM
     ("rdm", Stable, &["neon"]),
     // FEAT_SB
@@ -173,9 +203,11 @@ const AARCH64_ALLOWED_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     //
     // "For backwards compatibility, Neon and VFP are required in the latest architectures."
     ("sve", Stable, &["neon"]),
+    // FEAT_SVE_B16B16 (SVE or SME Instructions)
+    ("sve-b16b16", Unstable(sym::aarch64_unstable_target_feature), &["bf16"]),
     // FEAT_SVE2
     ("sve2", Stable, &["sve"]),
-    // FEAT_SVE2_AES
+    // FEAT_SVE_AES & FEAT_SVE_PMULL128
     ("sve2-aes", Stable, &["sve2", "aes"]),
     // FEAT_SVE2_BitPerm
     ("sve2-bitperm", Stable, &["sve2"]),
@@ -183,6 +215,8 @@ const AARCH64_ALLOWED_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ("sve2-sha3", Stable, &["sve2", "sha3"]),
     // FEAT_SVE2_SM4
     ("sve2-sm4", Stable, &["sve2", "sm4"]),
+    // FEAT_SVE2p1
+    ("sve2p1", Unstable(sym::aarch64_unstable_target_feature), &["sve2"]),
     // FEAT_TME
     ("tme", Stable, &[]),
     (
@@ -199,9 +233,19 @@ const AARCH64_ALLOWED_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ("v8.4a", Unstable(sym::aarch64_ver_target_feature), &["v8.3a", "dotprod", "dit", "flagm"]),
     ("v8.5a", Unstable(sym::aarch64_ver_target_feature), &["v8.4a", "ssbs", "sb", "dpb2", "bti"]),
     ("v8.6a", Unstable(sym::aarch64_ver_target_feature), &["v8.5a", "bf16", "i8mm"]),
-    ("v8.7a", Unstable(sym::aarch64_ver_target_feature), &[]),
+    ("v8.7a", Unstable(sym::aarch64_ver_target_feature), &["v8.6a", "wfxt"]),
+    ("v8.8a", Unstable(sym::aarch64_ver_target_feature), &["v8.7a", "hbc", "mops"]),
+    ("v8.9a", Unstable(sym::aarch64_ver_target_feature), &["v8.8a", "cssc"]),
+    ("v9.1a", Unstable(sym::aarch64_ver_target_feature), &["v9a", "v8.6a"]),
+    ("v9.2a", Unstable(sym::aarch64_ver_target_feature), &["v9.1a", "v8.7a"]),
+    ("v9.3a", Unstable(sym::aarch64_ver_target_feature), &["v9.2a", "v8.8a"]),
+    ("v9.4a", Unstable(sym::aarch64_ver_target_feature), &["v9.3a", "v8.9a"]),
+    ("v9.5a", Unstable(sym::aarch64_ver_target_feature), &["v9.4a"]),
+    ("v9a", Unstable(sym::aarch64_ver_target_feature), &["v8.5a", "sve2"]),
     // FEAT_VHE
     ("vh", Stable, &[]),
+    // FEAT_WFxT
+    ("wfxt", Unstable(sym::aarch64_unstable_target_feature), &[]),
     // tidy-alphabetical-end
 ];