Add Poly1305 bench

src/Makefile.bench.include

@@ -30,6 +30,7 @@ bench_bench_bitcoin_SOURCES = \
   bench/base58.cpp \
   bench/bech32.cpp \
   bench/lockedpool.cpp \
+  bench/poly1305.cpp \
   bench/prevector.cpp
 
 nodist_bench_bench_bitcoin_SOURCES = $(GENERATED_BENCH_FILES)

src/bench/poly1305.cpp

@@ -0,0 +1,41 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <iostream>
+
+#include <bench/bench.h>
+#include <crypto/poly1305.h>
+
+/* Number of bytes to process per iteration */
+static constexpr uint64_t BUFFER_SIZE_TINY  = 64;
+static constexpr uint64_t BUFFER_SIZE_SMALL = 256;
+static constexpr uint64_t BUFFER_SIZE_LARGE = 1024*1024;
+
+static void POLY1305(benchmark::State& state, size_t buffersize)
+{
+    std::vector<unsigned char> tag(POLY1305_TAGLEN, 0);
+    std::vector<unsigned char> key(POLY1305_KEYLEN, 0);
+    std::vector<unsigned char> in(buffersize, 0);
+    while (state.KeepRunning())
+        poly1305_auth(tag.data(), in.data(), in.size(), key.data());
+}
+
+static void POLY1305_64BYTES(benchmark::State& state)
+{
+    POLY1305(state, BUFFER_SIZE_TINY);
+}
+
+static void POLY1305_256BYTES(benchmark::State& state)
+{
+    POLY1305(state, BUFFER_SIZE_SMALL);
+}
+
+static void POLY1305_1MB(benchmark::State& state)
+{
+    POLY1305(state, BUFFER_SIZE_LARGE);
+}
+
+BENCHMARK(POLY1305_64BYTES, 500000);
+BENCHMARK(POLY1305_256BYTES, 250000);
+BENCHMARK(POLY1305_1MB, 340);