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

std/tests/run-time-detect.rs

@@ -4,6 +4,10 @@
     all(target_arch = "arm", any(target_os = "linux", target_os = "android")),
     feature(stdarch_arm_feature_detection)
 )]
+#![cfg_attr(
+    all(target_arch = "aarch64", any(target_os = "linux", target_os = "android")),
+    feature(stdarch_aarch64_feature_detection)
+)]
 #![cfg_attr(
     all(target_arch = "powerpc", target_os = "linux"),
     feature(stdarch_powerpc_feature_detection)
@@ -36,42 +40,59 @@ fn aarch64_linux() {
     println!("bf16: {}", is_aarch64_feature_detected!("bf16"));
     println!("bti: {}", is_aarch64_feature_detected!("bti"));
     println!("crc: {}", is_aarch64_feature_detected!("crc"));
+    println!("cssc: {}", is_aarch64_feature_detected!("cssc"));
     println!("dit: {}", is_aarch64_feature_detected!("dit"));
     println!("dotprod: {}", is_aarch64_feature_detected!("dotprod"));
     println!("dpb2: {}", is_aarch64_feature_detected!("dpb2"));
     println!("dpb: {}", is_aarch64_feature_detected!("dpb"));
+    println!("ecv: {}", is_aarch64_feature_detected!("ecv"));
     println!("f32mm: {}", is_aarch64_feature_detected!("f32mm"));
     println!("f64mm: {}", is_aarch64_feature_detected!("f64mm"));
+    println!("faminmax: {}", is_aarch64_feature_detected!("faminmax"));
     println!("fcma: {}", is_aarch64_feature_detected!("fcma"));
     println!("fhm: {}", is_aarch64_feature_detected!("fhm"));
+    println!("flagm2: {}", is_aarch64_feature_detected!("flagm2"));
     println!("flagm: {}", is_aarch64_feature_detected!("flagm"));
     println!("fp16: {}", is_aarch64_feature_detected!("fp16"));
+    println!("fp8: {}", is_aarch64_feature_detected!("fp8"));
+    println!("fp8dot2: {}", is_aarch64_feature_detected!("fp8dot2"));
+    println!("fp8dot4: {}", is_aarch64_feature_detected!("fp8dot4"));
+    println!("fp8fma: {}", is_aarch64_feature_detected!("fp8fma"));
+    println!("fpmr: {}", is_aarch64_feature_detected!("fpmr"));
     println!("frintts: {}", is_aarch64_feature_detected!("frintts"));
+    println!("hbc: {}", is_aarch64_feature_detected!("hbc"));
     println!("i8mm: {}", is_aarch64_feature_detected!("i8mm"));
     println!("jsconv: {}", is_aarch64_feature_detected!("jsconv"));
+    println!("lse128: {}", is_aarch64_feature_detected!("lse128"));
     println!("lse2: {}", is_aarch64_feature_detected!("lse2"));
     println!("lse: {}", is_aarch64_feature_detected!("lse"));
+    println!("lut: {}", is_aarch64_feature_detected!("lut"));
+    println!("mops: {}", is_aarch64_feature_detected!("mops"));
     println!("mte: {}", is_aarch64_feature_detected!("mte"));
     println!("neon: {}", is_aarch64_feature_detected!("neon"));
     println!("paca: {}", is_aarch64_feature_detected!("paca"));
     println!("pacg: {}", is_aarch64_feature_detected!("pacg"));
     println!("pmull: {}", is_aarch64_feature_detected!("pmull"));
     println!("rand: {}", is_aarch64_feature_detected!("rand"));
     println!("rcpc2: {}", is_aarch64_feature_detected!("rcpc2"));
+    println!("rcpc3: {}", is_aarch64_feature_detected!("rcpc3"));
     println!("rcpc: {}", is_aarch64_feature_detected!("rcpc"));
     println!("rdm: {}", is_aarch64_feature_detected!("rdm"));
     println!("sb: {}", is_aarch64_feature_detected!("sb"));
     println!("sha2: {}", is_aarch64_feature_detected!("sha2"));
     println!("sha3: {}", is_aarch64_feature_detected!("sha3"));
     println!("sm4: {}", is_aarch64_feature_detected!("sm4"));
     println!("ssbs: {}", is_aarch64_feature_detected!("ssbs"));
+    println!("sve-b16b16: {}", is_aarch64_feature_detected!("sve-b16b16"));
     println!("sve2-aes: {}", is_aarch64_feature_detected!("sve2-aes"));
     println!("sve2-bitperm: {}", is_aarch64_feature_detected!("sve2-bitperm"));
     println!("sve2-sha3: {}", is_aarch64_feature_detected!("sve2-sha3"));
     println!("sve2-sm4: {}", is_aarch64_feature_detected!("sve2-sm4"));
     println!("sve2: {}", is_aarch64_feature_detected!("sve2"));
+    println!("sve2p1: {}", is_aarch64_feature_detected!("sve2p1"));
     println!("sve: {}", is_aarch64_feature_detected!("sve"));
     println!("tme: {}", is_aarch64_feature_detected!("tme"));
+    println!("wfxt: {}", is_aarch64_feature_detected!("wfxt"));
     // tidy-alphabetical-end
 }