vectorized SliceContains

Author: LaihoE

library/core/src/slice/cmp.rs

@@ -257,3 +257,29 @@ impl SliceContains for i8 {
         memchr::memchr(byte, bytes).is_some()
     }
 }
+
+macro_rules! impl_slice_contains {
+    ($($t:ty),*) => {
+        $(
+            impl SliceContains for $t {
+                #[inline]
+                fn slice_contains(&self, arr: &[$t]) -> bool {
+                    // Make our LANE_COUNT 4x the normal lane count. The compiler will nicely unroll it.
+                    const LANE_COUNT: usize = 4 * (128 / (mem::size_of::<$t>() * 8));
+                    // SIMD
+                    let mut matches = [false; LANE_COUNT];
+                    for chunk in arr.chunks_exact(LANE_COUNT){
+                        matches.iter_mut().zip(chunk).for_each(|(m, x)| *m = *x == *self);
+                        if matches.iter().fold(false, |acc, x| acc | x) {
+                            return true;
+                        }
+                    }
+                    // Scalar remainder
+                    return arr.chunks_exact(LANE_COUNT).remainder().iter().any(|x| *x == *self);
+                }
+            }
+        )*
+    };
+}
+
+impl_slice_contains!(u16, u32, u64, i16, i32, i64, f32, f64, usize, isize);