Inside Bitcoin

1// Copyright (c) The Bitcoin Core developers
2// Distributed under the MIT software license, see the accompanying
3// file COPYING or https://opensource.org/license/mit.
4
5#include <bench/bench.h>
6#include <random.h>
7#include <uint256.h>
8
9#include <compare>
10#include <cstddef>
11#include <utility>
12#include <vector>
13
14namespace {
15
16enum class Difference {
17    NONE,
18    FIRST_BYTE,
19    LAST_BYTE,
20};
21
22constexpr size_t NUM_PAIRS{4'096};
23
24std::vector<std::pair<uint256, uint256>> MakePairs(Difference difference)
25{
26    FastRandomContext rng{/*fDeterministic=*/true};
27    std::vector<std::pair<uint256, uint256>> pairs;
28    pairs.reserve(NUM_PAIRS);
29
30    for (size_t i{0}; i < NUM_PAIRS; ++i) {
31        uint256 lhs{rng.rand256()};
32        uint256 rhs{lhs};
33        if (difference != Difference::NONE) {
34            const size_t position{difference == Difference::FIRST_BYTE ? 0 : uint256::size() - 1};
35            lhs.begin()[position] = i % 2 == 0 ? 0 : 255;
36            rhs.begin()[position] = i % 2 == 0 ? 255 : 0;
37        }
38        pairs.emplace_back(lhs, rhs);
39    }
40    return pairs;
41}
42
43template <typename Comparator>
44void Comparison(benchmark::Bench& bench, Difference difference, Comparator comparator)
45{
46    const auto pairs{MakePairs(difference)};
47    bench.batch(pairs.size()).unit("comparison").run([&] {
48        for (const auto& [lhs, rhs] : pairs) {
49            ankerl::nanobench::doNotOptimizeAway(comparator(lhs, rhs));
50        }
51    });
52}
53
54void Uint256EqualIdentical(benchmark::Bench& bench)
55{
56    Comparison(bench, Difference::NONE, [](const uint256& lhs, const uint256& rhs) { return lhs == rhs; });
57}
58
59void Uint256EqualFirstByteDifferent(benchmark::Bench& bench)
60{
61    Comparison(bench, Difference::FIRST_BYTE, [](const uint256& lhs, const uint256& rhs) { return lhs == rhs; });
62}
63
64void Uint256EqualLastByteDifferent(benchmark::Bench& bench)
65{
66    Comparison(bench, Difference::LAST_BYTE, [](const uint256& lhs, const uint256& rhs) { return lhs == rhs; });
67}
68
69void Uint256LessIdentical(benchmark::Bench& bench)
70{
71    Comparison(bench, Difference::NONE, [](const uint256& lhs, const uint256& rhs) { return lhs < rhs; });
72}
73
74void Uint256LessFirstByteDifferent(benchmark::Bench& bench)
75{
76    Comparison(bench, Difference::FIRST_BYTE, [](const uint256& lhs, const uint256& rhs) { return lhs < rhs; });
77}
78
79void Uint256LessLastByteDifferent(benchmark::Bench& bench)
80{
81    Comparison(bench, Difference::LAST_BYTE, [](const uint256& lhs, const uint256& rhs) { return lhs < rhs; });
82}
83
84} // namespace
85
86BENCHMARK(Uint256EqualIdentical);
87BENCHMARK(Uint256EqualFirstByteDifferent);
88BENCHMARK(Uint256EqualLastByteDifferent);
89BENCHMARK(Uint256LessIdentical);
90BENCHMARK(Uint256LessFirstByteDifferent);
91BENCHMARK(Uint256LessLastByteDifferent);
92