add a benchmark for slice_iter.copied().array_chunks()

Author: the8472

library/core/benches/iter.rs

@@ -1,4 +1,6 @@
 use core::iter::*;
+use core::mem;
+use core::num::Wrapping;
 use test::{black_box, Bencher};
 
 #[bench]
@@ -398,3 +400,21 @@ fn bench_trusted_random_access_adapters(b: &mut Bencher) {
         acc
     })
 }
+
+/// Exercises the iter::Copied specialization for slice::Iter
+#[bench]
+fn bench_copied_array_chunks(b: &mut Bencher) {
+    let v = vec![1u8; 1024];
+
+    b.iter(|| {
+        black_box(&v)
+            .iter()
+            .copied()
+            .array_chunks::<{ mem::size_of::<u64>() }>()
+            .map(|ary| {
+                let d = u64::from_ne_bytes(ary);
+                Wrapping(d.rotate_left(7).wrapping_add(1))
+            })
+            .sum::<Wrapping<u64>>()
+    })
+}

library/core/benches/lib.rs

@@ -4,6 +4,7 @@
 #![feature(int_log)]
 #![feature(test)]
 #![feature(trusted_random_access)]
+#![feature(iter_array_chunks)]
 
 extern crate test;