Run-time feature detection for Aarch64 on Windows.

Author: makotokato

crates/std_detect/src/detect/mod.rs

@@ -106,6 +106,9 @@ cfg_if! {
         mod aarch64;
         #[path = "os/freebsd/mod.rs"]
         mod os;
+    } else if #[cfg(all(target_os = "windows", target_arch = "aarch64"))] {
+        #[path = "os/windows/aarch64.rs"]
+        mod os;
     } else {
         #[path = "os/other.rs"]
         mod os;

crates/std_detect/src/detect/os/windows/aarch64.rs

@@ -0,0 +1,42 @@
+//! Run-time feature detection for Aarch64 on Windows.
+
+use crate::detect::{cache, Feature};
+
+/// Try to read the features from OS API.
+pub(crate) fn detect_features() -> cache::Initializer {
+    const PF_ARM_NEON_INSTRUCTIONS_AVAILABLE: u32 = 19;
+    const PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE: u32 = 30;
+    const PF_ARM_V8_CRC32_INSTRUCTIONS_AVAILABLE: u32 = 31;
+
+    extern "system" {
+        pub fn IsProcessorFeaturePresent(ProcessorFeature: u32) -> u32;
+    }
+
+    let mut value = cache::Initializer::default();
+    {
+        let mut enable_feature = |f, enable| {
+            if enable {
+                value.set(f as u32);
+            }
+        };
+
+        // Some features such Feature::fp may be supported on current CPU,
+        // but no way to detect it by OS API.
+
+        enable_feature(Feature::asimd, unsafe {
+            IsProcessorFeaturePresent(PF_ARM_NEON_INSTRUCTIONS_AVAILABLE) != 0
+        });
+        enable_feature(Feature::crc, unsafe {
+            IsProcessorFeaturePresent(PF_ARM_V8_CRC32_INSTRUCTIONS_AVAILABLE) != 0
+        });
+        // PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE means aes, sha1, sha2 and
+        // pmull supprot
+        enable_feature(Feature::crypto, unsafe {
+            IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE) != 0
+        });
+        enable_feature(Feature::pmull, unsafe {
+            IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE) != 0
+        });
+    }
+    value
+}