Add benchmarks for clone

Author: Amanieu

benches/bench.rs

@@ -206,3 +206,31 @@ bench_suite!(
     iter_ahash_random,
     iter_std_random
 );
+
+macro_rules! bench_clone {
+    ($name:ident, $maptype:ident, $keydist:expr) => {
+        #[bench]
+        fn $name(b: &mut Bencher) {
+            let mut m = $maptype::default();
+            let mut m2 = $maptype::default();
+            for i in ($keydist).take(SIZE * 10) {
+                m.insert(i, i);
+            }
+
+            b.iter(|| {
+                m2.clone_from(&m);
+                black_box(&mut m2);
+            })
+        }
+    };
+}
+
+bench_suite!(
+    bench_clone,
+    clone_ahash_serial,
+    clone_std_serial,
+    clone_ahash_highbits,
+    clone_std_highbits,
+    clone_ahash_random,
+    clone_std_random
+);