From 972697976c027b5199150a98e886c199b7ffc335 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C5=91rinc?= <pap.lorinc@gmail.com>
Date: Fri, 6 Dec 2024 16:18:03 +0100
Subject: [PATCH] bench: make ObfuscationBench more representative

A previous PR already solved the tiny byte-array-xors during serialization, so it makes sense to keep focusing on the performance of bigger continuous chunks.

This also renames the file from `xor` to `obfuscation` to enable scripted diff name unification later.

> C++ compiler .......................... GNU 14.2.0

|             ns/byte |              byte/s |    err% |        ins/byte |        cyc/byte |    IPC |       bra/byte |   miss% |     total | benchmark
|--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:----------
|                0.84 |    1,184,138,235.64 |    0.0% |            9.01 |            3.03 |  2.971 |           1.00 |    0.1% |      5.50 | `ObfuscationBench`

> C++ compiler .......................... Clang 20.1.7

|             ns/byte |              byte/s |    err% |        ins/byte |        cyc/byte |    IPC |       bra/byte |   miss% |     total | benchmark
|--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:----------
|                0.89 |    1,124,087,330.23 |    0.1% |            6.52 |            3.20 |  2.041 |           0.50 |    0.2% |      5.50 | `ObfuscationBench`
---
 src/bench/CMakeLists.txt               |  2 +-
 src/bench/{xor.cpp => obfuscation.cpp} | 11 ++++++-----
 2 files changed, 7 insertions(+), 6 deletions(-)
 rename src/bench/{xor.cpp => obfuscation.cpp} (59%)

diff --git a/src/bench/CMakeLists.txt b/src/bench/CMakeLists.txt
index 2137beccb5a..9f161876150 100644
--- a/src/bench/CMakeLists.txt
+++ b/src/bench/CMakeLists.txt
@@ -35,6 +35,7 @@ add_executable(bench_bitcoin
   mempool_eviction.cpp
   mempool_stress.cpp
   merkle_root.cpp
+  obfuscation.cpp
   parse_hex.cpp
   peer_eviction.cpp
   poly1305.cpp
@@ -51,7 +52,6 @@ add_executable(bench_bitcoin
   txgraph.cpp
   util_time.cpp
   verify_script.cpp
-  xor.cpp
 )
 
 include(TargetDataSources)
diff --git a/src/bench/xor.cpp b/src/bench/obfuscation.cpp
similarity index 59%
rename from src/bench/xor.cpp
rename to src/bench/obfuscation.cpp
index f3d6145c2b2..27a254f8037 100644
--- a/src/bench/xor.cpp
+++ b/src/bench/obfuscation.cpp
@@ -4,22 +4,23 @@
 
 #include <bench/bench.h>
 #include <random.h>
-#include <span.h>
 #include <streams.h>
 #include <util/obfuscation.h>
 
 #include <cstddef>
 #include <vector>
 
-static void Xor(benchmark::Bench& bench)
+static void ObfuscationBench(benchmark::Bench& bench)
 {
     FastRandomContext frc{/*fDeterministic=*/true};
     auto data{frc.randbytes<std::byte>(1024)};
-    auto key{frc.randbytes<std::byte>(Obfuscation::KEY_SIZE)};
+    const auto key{frc.randbytes<Obfuscation::KEY_SIZE>()};
 
+    size_t offset{0};
     bench.batch(data.size()).unit("byte").run([&] {
-        util::Xor(data, key);
+        util::Xor(data, key, offset++); // mutated differently each time
+        ankerl::nanobench::doNotOptimizeAway(data);
     });
 }
 
-BENCHMARK(Xor, benchmark::PriorityLevel::HIGH);
+BENCHMARK(ObfuscationBench, benchmark::PriorityLevel::HIGH);