use std for inputs < 64 bytes in cases where runtime dispatch is not used

Author: hkratz

src/implementation/x86/mod.rs

@@ -50,6 +50,10 @@ fn get_fastest_available_implementation_basic() -> super::ValidateUtf8Fn {
 pub(crate) unsafe fn validate_utf8_basic(
     input: &[u8],
 ) -> core::result::Result<(), crate::basic::Utf8Error> {
+    if input.len() < 64 {
+        return super::validate_utf8_basic_fallback(input);
+    }
+
     avx2::validate_utf8_basic(input)
 }
 
@@ -61,6 +65,10 @@ pub(crate) unsafe fn validate_utf8_basic(
 pub(crate) unsafe fn validate_utf8_basic(
     input: &[u8],
 ) -> core::result::Result<(), crate::basic::Utf8Error> {
+    if input.len() < 64 {
+        return super::validate_utf8_basic_fallback(input);
+    }
+
     sse42::validate_utf8_basic(input)
 }
 
@@ -118,6 +126,10 @@ fn get_fastest_available_implementation_compat() -> super::ValidateUtf8CompatFn
 pub(crate) unsafe fn validate_utf8_compat(
     input: &[u8],
 ) -> core::result::Result<(), crate::compat::Utf8Error> {
+    if input.len() < 64 {
+        return super::validate_utf8_compat_fallback(input);
+    }
+
     avx2::validate_utf8_compat(input)
 }
 
@@ -129,6 +141,10 @@ pub(crate) unsafe fn validate_utf8_compat(
 pub(crate) unsafe fn validate_utf8_compat(
     input: &[u8],
 ) -> core::result::Result<(), crate::compat::Utf8Error> {
+    if input.len() < 64 {
+        return super::validate_utf8_compat_fallback(input);
+    }
+
     sse42::validate_utf8_compat(input)
 }