fix: update the implementation of _kshiftri_mask8 and _kshiftli_mask8 to

zero out when the amount of shift exceeds the bit length of the input
argument.

Author: madhav-madhusoodanan

crates/core_arch/src/x86/avx512dq.rs

@@ -4602,7 +4602,7 @@ pub fn _kortestz_mask8_u8(a: __mmask8, b: __mmask8) -> u8 {
 #[rustc_legacy_const_generics(1)]
 #[stable(feature = "stdarch_x86_avx512", since = "1.89")]
 pub fn _kshiftli_mask8<const COUNT: u32>(a: __mmask8) -> __mmask8 {
-    a << COUNT
+    a.unbounded_shl(COUNT)
 }
 
 /// Shift 8-bit mask a right by count bits while shifting in zeros, and store the result in dst.
@@ -4613,7 +4613,7 @@ pub fn _kshiftli_mask8<const COUNT: u32>(a: __mmask8) -> __mmask8 {
 #[rustc_legacy_const_generics(1)]
 #[stable(feature = "stdarch_x86_avx512", since = "1.89")]
 pub fn _kshiftri_mask8<const COUNT: u32>(a: __mmask8) -> __mmask8 {
-    a >> COUNT
+    a.unbounded_shr(COUNT)
 }
 
 /// Compute the bitwise AND of 16-bit masks a and b, and if the result is all zeros, store 1 in dst,
@@ -9856,13 +9856,37 @@ mod tests {
         let r = _kshiftli_mask8::<3>(a);
         let e: __mmask8 = 0b01001000;
         assert_eq!(r, e);
+
+        let r = _kshiftli_mask8::<7>(a);
+        let e: __mmask8 = 0b10000000;
+        assert_eq!(r, e);
+
+        let r = _kshiftli_mask8::<8>(a);
+        let e: __mmask8 = 0b00000000;
+        assert_eq!(r, e);
+
+        let r = _kshiftli_mask8::<9>(a);
+        let e: __mmask8 = 0b00000000;
+        assert_eq!(r, e);
     }
 
     #[simd_test(enable = "avx512dq")]
     unsafe fn test_kshiftri_mask8() {
-        let a: __mmask8 = 0b01101001;
+        let a: __mmask8 = 0b10101001;
         let r = _kshiftri_mask8::<3>(a);
-        let e: __mmask8 = 0b00001101;
+        let e: __mmask8 = 0b00010101;
+        assert_eq!(r, e);
+
+        let r = _kshiftri_mask8::<7>(a);
+        let e: __mmask8 = 0b00000001;
+        assert_eq!(r, e);
+
+        let r = _kshiftri_mask8::<8>(a);
+        let e: __mmask8 = 0b00000000;
+        assert_eq!(r, e);
+
+        let r = _kshiftri_mask8::<9>(a);
+        let e: __mmask8 = 0b00000000;
         assert_eq!(r, e);
     }