convert _mm_extract_epi64 to const generics

Author: lqd

crates/core_arch/src/x86_64/sse41.rs

@@ -8,20 +8,17 @@ use crate::{
 #[cfg(test)]
 use stdarch_test::assert_instr;
 
-/// Extracts an 64-bit integer from `a` selected with `imm8`
+/// Extracts an 64-bit integer from `a` selected with `IMM1`
 ///
 /// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm_extract_epi64)
 #[inline]
 #[target_feature(enable = "sse4.1")]
-#[cfg_attr(all(test, not(target_os = "windows")), assert_instr(pextrq, imm8 = 1))]
-#[rustc_args_required_const(1)]
+#[cfg_attr(all(test, not(target_os = "windows")), assert_instr(pextrq, IMM1 = 1))]
+#[rustc_legacy_const_generics(1)]
 #[stable(feature = "simd_x86", since = "1.27.0")]
-pub unsafe fn _mm_extract_epi64(a: __m128i, imm8: i32) -> i64 {
-    let a = a.as_i64x2();
-    match imm8 & 1 {
-        0 => simd_extract(a, 0),
-        _ => simd_extract(a, 1),
-    }
+pub unsafe fn _mm_extract_epi64<const IMM1: i32>(a: __m128i) -> i64 {
+    static_assert_imm1!(IMM1);
+    simd_extract(a.as_i64x2(), IMM1 as u32)
 }
 
 /// Returns a copy of `a` with the 64-bit integer from `i` inserted at a
@@ -49,10 +46,10 @@ mod tests {
     #[simd_test(enable = "sse4.1")]
     unsafe fn test_mm_extract_epi64() {
         let a = _mm_setr_epi64x(0, 1);
-        let r = _mm_extract_epi64(a, 1);
-        assert_eq!(r, 1);
-        let r = _mm_extract_epi64(a, 3);
+        let r = _mm_extract_epi64::<1>(a);
         assert_eq!(r, 1);
+        let r = _mm_extract_epi64::<0>(a);
+        assert_eq!(r, 0);
     }
 
     #[simd_test(enable = "sse4.1")]