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Add direct object baselines and branch-prediction-resistant jitter to protocol benchmarks #58

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Add direct object baselines and branch-prediction-resistant jitter to protocol benchmarks #58

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2776138
Add direct object baselines and branch-prediction-resistant jitter to…
jbcoe Apr 5, 2026
ba2ec52
Change loop index type from int to size_t to address review comment
jbcoe Apr 5, 2026
5b06d9e
Merge branch 'main' into jbcoe/benchmark-improvements
jbcoe Apr 5, 2026
eee9bf2
Merge branch 'main' into jbcoe/benchmark-improvements
jbcoe Apr 8, 2026
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125 changes: 125 additions & 0 deletions protocol_benchmark.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -15,9 +15,27 @@ struct ALike {
int count() { return 42; }
};

struct ALikeToo {
std::string_view name() const { return "ALikeToo"; }

int count() { return 99; }
};

// Member function call benchmarks
static void Direct_Call(benchmark::State& state) {
ALike a;
benchmark::DoNotOptimize(a);
for (auto _ : state) {
benchmark::DoNotOptimize(a.name());
benchmark::DoNotOptimize(a.count());
}
}

BENCHMARK(Direct_Call);

static void Protocol_Virtual_Call(benchmark::State& state) {
xyz::protocol<xyz::A_virtual> p(std::in_place_type<ALike>);
benchmark::DoNotOptimize(p);
for (auto _ : state) {
benchmark::DoNotOptimize(p.name());
benchmark::DoNotOptimize(p.count());
Expand All @@ -28,6 +46,7 @@ BENCHMARK(Protocol_Virtual_Call);

static void Protocol_Manual_Call(benchmark::State& state) {
xyz::protocol<xyz::A_manual> p(std::in_place_type<ALike>);
benchmark::DoNotOptimize(p);
for (auto _ : state) {
benchmark::DoNotOptimize(p.name());
benchmark::DoNotOptimize(p.count());
Expand All @@ -37,6 +56,16 @@ static void Protocol_Manual_Call(benchmark::State& state) {
BENCHMARK(Protocol_Manual_Call);

// Copy construction benchmarks
static void Direct_Copy(benchmark::State& state) {
ALike a;
for (auto _ : state) {
ALike copy(a);
benchmark::DoNotOptimize(copy);
}
}

BENCHMARK(Direct_Copy);

static void Protocol_Virtual_Copy(benchmark::State& state) {
xyz::protocol<xyz::A_virtual> p(std::in_place_type<ALike>);
for (auto _ : state) {
Expand All @@ -58,6 +87,18 @@ static void Protocol_Manual_Copy(benchmark::State& state) {
BENCHMARK(Protocol_Manual_Copy);

// Move construction/assignment benchmarks
static void Direct_Move(benchmark::State& state) {
ALike a;
for (auto _ : state) {
ALike moved(std::move(a));
benchmark::DoNotOptimize(moved);
a = std::move(moved);
benchmark::DoNotOptimize(a);
}
}

BENCHMARK(Direct_Move);

static void Protocol_Virtual_Move(benchmark::State& state) {
xyz::protocol<xyz::A_virtual> p(std::in_place_type<ALike>);
for (auto _ : state) {
Expand All @@ -83,6 +124,18 @@ static void Protocol_Manual_Move(benchmark::State& state) {
BENCHMARK(Protocol_Manual_Move);

// Swap benchmarks
static void Direct_Swap(benchmark::State& state) {
ALike a1;
ALike a2;
for (auto _ : state) {
std::swap(a1, a2);
benchmark::DoNotOptimize(a1);
benchmark::DoNotOptimize(a2);
}
}

BENCHMARK(Direct_Swap);

static void Protocol_Virtual_Swap(benchmark::State& state) {
xyz::protocol<xyz::A_virtual> p1(std::in_place_type<ALike>);
xyz::protocol<xyz::A_virtual> p2(std::in_place_type<ALike>);
Expand All @@ -108,6 +161,15 @@ static void Protocol_Manual_Swap(benchmark::State& state) {
BENCHMARK(Protocol_Manual_Swap);

// Construction and Destruction benchmarks
static void Direct_CtorDtor(benchmark::State& state) {
for (auto _ : state) {
ALike a;
benchmark::DoNotOptimize(a);
}
}

BENCHMARK(Direct_CtorDtor);

static void Protocol_Virtual_CtorDtor(benchmark::State& state) {
for (auto _ : state) {
xyz::protocol<xyz::A_virtual> p(std::in_place_type<ALike>);
Expand All @@ -130,6 +192,7 @@ BENCHMARK(Protocol_Manual_CtorDtor);
static void ProtocolView_Virtual_Call(benchmark::State& state) {
ALike alike;
xyz::protocol_view<xyz::A_virtual> view(alike);
benchmark::DoNotOptimize(view);
for (auto _ : state) {
benchmark::DoNotOptimize(view.name());
benchmark::DoNotOptimize(view.count());
Expand All @@ -141,6 +204,7 @@ BENCHMARK(ProtocolView_Virtual_Call);
static void ProtocolView_Manual_Call(benchmark::State& state) {
ALike alike;
xyz::protocol_view<xyz::A_manual> view(alike);
benchmark::DoNotOptimize(view);
for (auto _ : state) {
benchmark::DoNotOptimize(view.name());
benchmark::DoNotOptimize(view.count());
Expand All @@ -152,6 +216,7 @@ BENCHMARK(ProtocolView_Manual_Call);
static void RawPointer_Call(benchmark::State& state) {
ALike alike;
ALike* ptr = &alike;
benchmark::DoNotOptimize(ptr);
for (auto _ : state) {
benchmark::DoNotOptimize(ptr->name());
benchmark::DoNotOptimize(ptr->count());
Expand All @@ -160,6 +225,66 @@ static void RawPointer_Call(benchmark::State& state) {

BENCHMARK(RawPointer_Call);

// Jitter benchmarks to defeat branch prediction
static void ProtocolView_Virtual_Call_Jitter(benchmark::State& state) {
ALike a1;
ALikeToo a2;
xyz::protocol_view<xyz::A_virtual> views[2] = {
xyz::protocol_view<xyz::A_virtual>(a1),
xyz::protocol_view<xyz::A_virtual>(a2)};

benchmark::DoNotOptimize(views);

size_t i = 0;
for (auto _ : state) {
auto& view = views[i & 1];
benchmark::DoNotOptimize(view.name());
benchmark::DoNotOptimize(view.count());
++i;
}
}

BENCHMARK(ProtocolView_Virtual_Call_Jitter);

static void ProtocolView_Manual_Call_Jitter(benchmark::State& state) {
ALike a1;
ALikeToo a2;
xyz::protocol_view<xyz::A_manual> views[2] = {
xyz::protocol_view<xyz::A_manual>(a1),
xyz::protocol_view<xyz::A_manual>(a2)};

benchmark::DoNotOptimize(views);

size_t i = 0;
for (auto _ : state) {
auto& view = views[i & 1];
benchmark::DoNotOptimize(view.name());
benchmark::DoNotOptimize(view.count());
++i;
}
}

BENCHMARK(ProtocolView_Manual_Call_Jitter);

static void RawPointer_Call_Jitter(benchmark::State& state) {
ALike a1;
ALike a2; // Raw pointer array must be of the same type, so this is just to
// measure the array overhead
ALike* ptrs[2] = {&a1, &a2};

benchmark::DoNotOptimize(ptrs);

size_t i = 0;
for (auto _ : state) {
auto* ptr = ptrs[i & 1];
benchmark::DoNotOptimize(ptr->name());
benchmark::DoNotOptimize(ptr->count());
++i;
}
}

BENCHMARK(RawPointer_Call_Jitter);

} // namespace

BENCHMARK_MAIN();
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