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Diffstat (limited to 'absl/strings/charconv_benchmark.cc')
| -rw-r--r-- | absl/strings/charconv_benchmark.cc | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/absl/strings/charconv_benchmark.cc b/absl/strings/charconv_benchmark.cc new file mode 100644 index 00000000..fd83f44e --- /dev/null +++ b/absl/strings/charconv_benchmark.cc @@ -0,0 +1,204 @@ +// Copyright 2018 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 "absl/strings/charconv.h" + +#include <cstdlib> +#include <cstring> +#include <string> + +#include "benchmark/benchmark.h" + +namespace { + +void BM_Strtod_Pi(benchmark::State& state) { + const char* pi = "3.14159"; + for (auto s : state) { + benchmark::DoNotOptimize(pi); + benchmark::DoNotOptimize(strtod(pi, nullptr)); + } +} +BENCHMARK(BM_Strtod_Pi); + +void BM_Absl_Pi(benchmark::State& state) { + const char* pi = "3.14159"; + const char* pi_end = pi + strlen(pi); + for (auto s : state) { + benchmark::DoNotOptimize(pi); + double v; + absl::from_chars(pi, pi_end, v); + benchmark::DoNotOptimize(v); + } +} +BENCHMARK(BM_Absl_Pi); + +void BM_Strtod_Pi_float(benchmark::State& state) { + const char* pi = "3.14159"; + for (auto s : state) { + benchmark::DoNotOptimize(pi); + benchmark::DoNotOptimize(strtof(pi, nullptr)); + } +} +BENCHMARK(BM_Strtod_Pi_float); + +void BM_Absl_Pi_float(benchmark::State& state) { + const char* pi = "3.14159"; + const char* pi_end = pi + strlen(pi); + for (auto s : state) { + benchmark::DoNotOptimize(pi); + float v; + absl::from_chars(pi, pi_end, v); + benchmark::DoNotOptimize(v); + } +} +BENCHMARK(BM_Absl_Pi_float); + +void BM_Strtod_HardLarge(benchmark::State& state) { + const char* num = "272104041512242479.e200"; + for (auto s : state) { + benchmark::DoNotOptimize(num); + benchmark::DoNotOptimize(strtod(num, nullptr)); + } +} +BENCHMARK(BM_Strtod_HardLarge); + +void BM_Absl_HardLarge(benchmark::State& state) { + const char* numstr = "272104041512242479.e200"; + const char* numstr_end = numstr + strlen(numstr); + for (auto s : state) { + benchmark::DoNotOptimize(numstr); + double v; + absl::from_chars(numstr, numstr_end, v); + benchmark::DoNotOptimize(v); + } +} +BENCHMARK(BM_Absl_HardLarge); + +void BM_Strtod_HardSmall(benchmark::State& state) { + const char* num = "94080055902682397.e-242"; + for (auto s : state) { + benchmark::DoNotOptimize(num); + benchmark::DoNotOptimize(strtod(num, nullptr)); + } +} +BENCHMARK(BM_Strtod_HardSmall); + +void BM_Absl_HardSmall(benchmark::State& state) { + const char* numstr = "94080055902682397.e-242"; + const char* numstr_end = numstr + strlen(numstr); + for (auto s : state) { + benchmark::DoNotOptimize(numstr); + double v; + absl::from_chars(numstr, numstr_end, v); + benchmark::DoNotOptimize(v); + } +} +BENCHMARK(BM_Absl_HardSmall); + +void BM_Strtod_HugeMantissa(benchmark::State& state) { + std::string huge(200, '3'); + const char* num = huge.c_str(); + for (auto s : state) { + benchmark::DoNotOptimize(num); + benchmark::DoNotOptimize(strtod(num, nullptr)); + } +} +BENCHMARK(BM_Strtod_HugeMantissa); + +void BM_Absl_HugeMantissa(benchmark::State& state) { + std::string huge(200, '3'); + const char* num = huge.c_str(); + const char* num_end = num + 200; + for (auto s : state) { + benchmark::DoNotOptimize(num); + double v; + absl::from_chars(num, num_end, v); + benchmark::DoNotOptimize(v); + } +} +BENCHMARK(BM_Absl_HugeMantissa); + +std::string MakeHardCase(int length) { + // The number 1.1521...e-297 is exactly halfway between 12345 * 2**-1000 and + // the next larger representable number. The digits of this number are in + // the std::string below. + const std::string digits = + "1." + "152113937042223790993097181572444900347587985074226836242307364987727724" + "831384300183638649152607195040591791364113930628852279348613864894524591" + "272746490313676832900762939595690019745859128071117417798540258114233761" + "012939937017879509401007964861774960297319002612457273148497158989073482" + "171377406078223015359818300988676687994537274548940612510414856761641652" + "513434981938564294004070500716200446656421722229202383105446378511678258" + "370570631774499359748259931676320916632111681001853983492795053244971606" + "922718923011680846577744433974087653954904214152517799883551075537146316" + "168973685866425605046988661997658648354773076621610279716804960009043764" + "038392994055171112475093876476783502487512538082706095923790634572014823" + "78877699375152587890625" + + std::string(5000, '0'); + // generate the hard cases on either side for the given length. + // Lengths between 3 and 1000 are reasonable. + return digits.substr(0, length) + "1e-297"; +} + +void BM_Strtod_Big_And_Difficult(benchmark::State& state) { + std::string testcase = MakeHardCase(state.range(0)); + const char* begin = testcase.c_str(); + for (auto s : state) { + benchmark::DoNotOptimize(begin); + benchmark::DoNotOptimize(strtod(begin, nullptr)); + } +} +BENCHMARK(BM_Strtod_Big_And_Difficult)->Range(3, 5000); + +void BM_Absl_Big_And_Difficult(benchmark::State& state) { + std::string testcase = MakeHardCase(state.range(0)); + const char* begin = testcase.c_str(); + const char* end = begin + testcase.size(); + for (auto s : state) { + benchmark::DoNotOptimize(begin); + double v; + absl::from_chars(begin, end, v); + benchmark::DoNotOptimize(v); + } +} +BENCHMARK(BM_Absl_Big_And_Difficult)->Range(3, 5000); + +} // namespace + +// ------------------------------------------------------------------------ +// Benchmark Time CPU Iterations +// ------------------------------------------------------------------------ +// BM_Strtod_Pi 96 ns 96 ns 6337454 +// BM_Absl_Pi 35 ns 35 ns 20031996 +// BM_Strtod_Pi_float 91 ns 91 ns 7745851 +// BM_Absl_Pi_float 35 ns 35 ns 20430298 +// BM_Strtod_HardLarge 133 ns 133 ns 5288341 +// BM_Absl_HardLarge 181 ns 181 ns 3855615 +// BM_Strtod_HardSmall 279 ns 279 ns 2517243 +// BM_Absl_HardSmall 287 ns 287 ns 2458744 +// BM_Strtod_HugeMantissa 433 ns 433 ns 1604293 +// BM_Absl_HugeMantissa 160 ns 160 ns 4403671 +// BM_Strtod_Big_And_Difficult/3 236 ns 236 ns 2942496 +// BM_Strtod_Big_And_Difficult/8 232 ns 232 ns 2983796 +// BM_Strtod_Big_And_Difficult/64 437 ns 437 ns 1591951 +// BM_Strtod_Big_And_Difficult/512 1738 ns 1738 ns 402519 +// BM_Strtod_Big_And_Difficult/4096 3943 ns 3943 ns 176128 +// BM_Strtod_Big_And_Difficult/5000 4397 ns 4397 ns 157878 +// BM_Absl_Big_And_Difficult/3 39 ns 39 ns 17799583 +// BM_Absl_Big_And_Difficult/8 43 ns 43 ns 16096859 +// BM_Absl_Big_And_Difficult/64 550 ns 550 ns 1259717 +// BM_Absl_Big_And_Difficult/512 4167 ns 4167 ns 171414 +// BM_Absl_Big_And_Difficult/4096 9160 ns 9159 ns 76297 +// BM_Absl_Big_And_Difficult/5000 9738 ns 9738 ns 70140 |