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Diffstat (limited to 'absl/algorithm/equal_benchmark.cc')
-rw-r--r-- | absl/algorithm/equal_benchmark.cc | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/absl/algorithm/equal_benchmark.cc b/absl/algorithm/equal_benchmark.cc new file mode 100644 index 00000000..fea6d137 --- /dev/null +++ b/absl/algorithm/equal_benchmark.cc @@ -0,0 +1,128 @@ +// Copyright 2017 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#include <cstdint> +#include <cstring> + +#include "absl/algorithm/algorithm.h" +#include "benchmark/benchmark.h" + +namespace { + +// The range of sequence sizes to benchmark. +constexpr int kMinBenchmarkSize = 1024; +constexpr int kMaxBenchmarkSize = 8 * 1024 * 1024; + +// A user-defined type for use in equality benchmarks. Note that we expect +// std::memcmp to win for this type: libstdc++'s std::equal only defers to +// memcmp for integral types. This is because it is not straightforward to +// guarantee that std::memcmp would produce a result "as-if" compared by +// operator== for other types (example gotchas: NaN floats, structs with +// padding). +struct EightBits { + explicit EightBits(int /* unused */) : data(0) {} + bool operator==(const EightBits& rhs) const { return data == rhs.data; } + uint8_t data; +}; + +template <typename T> +void BM_absl_equal_benchmark(benchmark::State& state) { + std::vector<T> xs(state.range(0), T(0)); + std::vector<T> ys = xs; + while (state.KeepRunning()) { + const bool same = absl::equal(xs.begin(), xs.end(), ys.begin(), ys.end()); + benchmark::DoNotOptimize(same); + } +} + +template <typename T> +void BM_std_equal_benchmark(benchmark::State& state) { + std::vector<T> xs(state.range(0), T(0)); + std::vector<T> ys = xs; + while (state.KeepRunning()) { + const bool same = std::equal(xs.begin(), xs.end(), ys.begin()); + benchmark::DoNotOptimize(same); + } +} + +template <typename T> +void BM_memcmp_benchmark(benchmark::State& state) { + std::vector<T> xs(state.range(0), T(0)); + std::vector<T> ys = xs; + while (state.KeepRunning()) { + const bool same = + std::memcmp(xs.data(), ys.data(), xs.size() * sizeof(T)) == 0; + benchmark::DoNotOptimize(same); + } +} + +// The expectation is that the compiler should be able to elide the equality +// comparison altogether for sufficiently simple types. +template <typename T> +void BM_absl_equal_self_benchmark(benchmark::State& state) { + std::vector<T> xs(state.range(0), T(0)); + while (state.KeepRunning()) { + const bool same = absl::equal(xs.begin(), xs.end(), xs.begin(), xs.end()); + benchmark::DoNotOptimize(same); + } +} + +BENCHMARK_TEMPLATE(BM_absl_equal_benchmark, uint8_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_std_equal_benchmark, uint8_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_memcmp_benchmark, uint8_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_absl_equal_self_benchmark, uint8_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); + +BENCHMARK_TEMPLATE(BM_absl_equal_benchmark, uint16_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_std_equal_benchmark, uint16_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_memcmp_benchmark, uint16_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_absl_equal_self_benchmark, uint16_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); + +BENCHMARK_TEMPLATE(BM_absl_equal_benchmark, uint32_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_std_equal_benchmark, uint32_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_memcmp_benchmark, uint32_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_absl_equal_self_benchmark, uint32_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); + +BENCHMARK_TEMPLATE(BM_absl_equal_benchmark, uint64_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_std_equal_benchmark, uint64_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_memcmp_benchmark, uint64_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_absl_equal_self_benchmark, uint64_t) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); + +BENCHMARK_TEMPLATE(BM_absl_equal_benchmark, EightBits) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_std_equal_benchmark, EightBits) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_memcmp_benchmark, EightBits) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); +BENCHMARK_TEMPLATE(BM_absl_equal_self_benchmark, EightBits) + ->Range(kMinBenchmarkSize, kMaxBenchmarkSize); + +} // namespace + +BENCHMARK_MAIN(); |