diff --git a/library/stdarch/crates/core_arch/src/x86/avx512bw.rs b/library/stdarch/crates/core_arch/src/x86/avx512bw.rs
index ccf30f9d9605..a98c445f38ab 100644
--- a/library/stdarch/crates/core_arch/src/x86/avx512bw.rs
+++ b/library/stdarch/crates/core_arch/src/x86/avx512bw.rs
@@ -9131,21 +9131,16 @@ pub unsafe fn _mm256_maskz_alignr_epi8<const IMM8: i32>(
 /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm_mask_alignr_epi8&expand=258)
 #[inline]
 #[target_feature(enable = "avx512bw,avx512vl")]
-#[rustc_args_required_const(4)]
-#[cfg_attr(test, assert_instr(vpalignr, imm8 = 5))]
-pub unsafe fn _mm_mask_alignr_epi8(
+#[rustc_legacy_const_generics(4)]
+#[cfg_attr(test, assert_instr(vpalignr, IMM8 = 5))]
+pub unsafe fn _mm_mask_alignr_epi8<const IMM8: i32>(
     src: __m128i,
     k: __mmask16,
     a: __m128i,
     b: __m128i,
-    imm8: i32,
 ) -> __m128i {
-    macro_rules! call {
-        ($imm8:expr) => {
-            _mm_alignr_epi8(a, b, $imm8)
-        };
-    }
-    let r = constify_imm8_sae!(imm8, call);
+    static_assert_imm8!(IMM8);
+    let r = _mm_alignr_epi8(a, b, IMM8);
     transmute(simd_select_bitmask(k, r.as_i8x16(), src.as_i8x16()))
 }
 
@@ -17782,9 +17777,9 @@ mod tests {
     unsafe fn test_mm_mask_alignr_epi8() {
         let a = _mm_set_epi8(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0);
         let b = _mm_set1_epi8(1);
-        let r = _mm_mask_alignr_epi8(a, 0, a, b, 14);
+        let r = _mm_mask_alignr_epi8::<14>(a, 0, a, b);
         assert_eq_m128i(r, a);
-        let r = _mm_mask_alignr_epi8(a, 0b11111111_11111111, a, b, 14);
+        let r = _mm_mask_alignr_epi8::<14>(a, 0b11111111_11111111, a, b);
         let e = _mm_set_epi8(0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1);
         assert_eq_m128i(r, e);
     }