skip the cache when features are statically enabled

Author: folkertdev

zlib-rs/src/cpu_features.rs

@@ -29,23 +29,32 @@ pub fn is_enabled_sse42() -> bool {
 #[inline(always)]
 pub fn is_enabled_avx2_and_bmi2() -> bool {
     #[cfg(any(target_arch = "x86_64", target_arch = "x86"))]
-    #[cfg(feature = "std")]
     {
-        use std::sync::atomic::{AtomicU32, Ordering};
-
-        static CACHE: AtomicU32 = AtomicU32::new(2);
-
-        return match CACHE.load(Ordering::Relaxed) {
-            0 => false,
-            1 => true,
-            _ => {
-                let detected = std::is_x86_feature_detected!("avx2")
-                    && std::is_x86_feature_detected!("bmi1")
-                    && std::is_x86_feature_detected!("bmi2");
-                CACHE.store(u32::from(detected), Ordering::Relaxed);
-                detected
-            }
-        };
+        #[cfg(all(
+            target_feature = "avx2",
+            target_feature = "bmi1",
+            target_feature = "bmi2"
+        ))]
+        return true;
+
+        #[cfg(feature = "std")]
+        {
+            use std::sync::atomic::{AtomicU32, Ordering};
+
+            static CACHE: AtomicU32 = AtomicU32::new(2);
+
+            return match CACHE.load(Ordering::Relaxed) {
+                0 => false,
+                1 => true,
+                _ => {
+                    let detected = std::is_x86_feature_detected!("avx2")
+                        && std::is_x86_feature_detected!("bmi1")
+                        && std::is_x86_feature_detected!("bmi2");
+                    CACHE.store(u32::from(detected), Ordering::Relaxed);
+                    detected
+                }
+            };
+        }
     }
 
     false