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+// 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();