Don't use std for small strings if avx512 is compile-time selected.

Author: hkratz

src/implementation/mod.rs

@@ -99,6 +99,7 @@ pub(crate) mod portable;
 
 // fallback method implementations
 #[inline]
+#[allow(dead_code)] // unused if AVX512 is selected at compile-time
 pub(crate) fn validate_utf8_basic_fallback(input: &[u8]) -> Result<(), crate::basic::Utf8Error> {
     match core::str::from_utf8(input) {
         Ok(_) => Ok(()),
@@ -107,6 +108,7 @@ pub(crate) fn validate_utf8_basic_fallback(input: &[u8]) -> Result<(), crate::ba
 }
 
 #[inline]
+#[allow(dead_code)] // unused if AVX512 is selected at compile-time
 pub(crate) fn validate_utf8_compat_fallback(input: &[u8]) -> Result<(), crate::compat::Utf8Error> {
     // SAFETY: 0 is always in bounds
     unsafe { helpers::validate_utf8_at_offset(input, 0) }

src/implementation/x86/mod.rs

@@ -156,10 +156,6 @@ 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() < super::helpers::SIMD_CHUNK_SIZE {
-        return super::validate_utf8_basic_fallback(input);
-    }
-
     validate_utf8_basic_avx512(input)
 }
 
@@ -363,10 +359,6 @@ 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() < super::helpers::SIMD_CHUNK_SIZE {
-        return super::validate_utf8_compat_fallback(input);
-    }
-
     validate_utf8_compat_avx512(input)
 }