Merge rust-bitcoin#4963: Add bench for sha3_256

589cebc hashes: Add bench for `sha3_256` (rustaceanrob)

Pull request description:

  Following up on the addition of the SHA3-256 hash, it may be worthwhile to strive for improvements. In my runs of the benchmark, small slices perform poorly, indicating to me there may be something wrong with the padding. As input size increases the hash is on the order of the slower hashes in the library, which is acceptable for the use case. Those that want to try to improve the hash will need this bench.


ACKs for top commit:
  apoelstra:
    ACK 589cebc; successfully ran local tests
  tcharding:
    ACK 589cebc


Tree-SHA512: 0114882e502f4abd2212a39ec08e1527e7f05b802bebaf744590fbaa04b3cd314b536fff9eae4b8fe3445a9cb0c95094e54d8c27ca54cec7f26ccc6d34470f99

Author: apoelstra

hashes/src/sha3_256/benches.rs

@@ -0,0 +1,33 @@
+use test::Bencher;
+
+use crate::{Hash, HashEngine};
+
+#[bench]
+pub fn sha3_256_10(bh: &mut Bencher) {
+    let mut engine = crate::sha3_256::Hash::engine();
+    let bytes = [1u8; 10];
+    bh.iter(|| {
+        engine.input(&bytes);
+    });
+    bh.bytes = bytes.len() as u64;
+}
+
+#[bench]
+pub fn sha3_256_1k(bh: &mut Bencher) {
+    let mut engine = crate::sha3_256::Hash::engine();
+    let bytes = [1u8; 1024];
+    bh.iter(|| {
+        engine.input(&bytes);
+    });
+    bh.bytes = bytes.len() as u64;
+}
+
+#[bench]
+pub fn sha3_256_64k(bh: &mut Bencher) {
+    let mut engine = crate::sha3_256::Hash::engine();
+    let bytes = [1u8; 65536];
+    bh.iter(|| {
+        engine.input(&bytes);
+    });
+    bh.bytes = bytes.len() as u64;
+}

hashes/src/sha3_256/mod.rs

@@ -17,6 +17,8 @@
 //
 // To read this file, follow the example code: https://keccak.team/keccak_specs_summary.html
 // For a detailed specification: https://keccak.team/files/Keccak-reference-3.0.pdf
+#[cfg(bench)]
+mod benches;
 use core::fmt;
 
 crate::internal_macros::general_hash_type! {