use std::str::from_utf8() for inputs < 64 bytes

Author: hkratz

src/implementation/x86/mod.rs

@@ -24,6 +24,10 @@ pub(crate) unsafe fn validate_utf8_basic(
         (fun)(input)
     }
 
+    if input.len() < 64 {
+        return super::validate_utf8_basic_fallback(input);
+    }
+
     let fun = FN.load(Ordering::Relaxed);
     mem::transmute::<FnRaw, super::ValidateUtf8Fn>(fun)(input)
 }
@@ -88,6 +92,10 @@ pub(crate) unsafe fn validate_utf8_compat(
         (fun)(input)
     }
 
+    if input.len() < 64 {
+        return super::validate_utf8_compat_fallback(input);
+    }
+
     let fun = FN.load(Ordering::Relaxed);
     mem::transmute::<FnRaw, super::ValidateUtf8CompatFn>(fun)(input)
 }