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Diffstat (limited to 'third_party/abseil_cpp/absl/strings/string_view_benchmark.cc')
| -rw-r--r-- | third_party/abseil_cpp/absl/strings/string_view_benchmark.cc | 381 |
1 files changed, 0 insertions, 381 deletions
diff --git a/third_party/abseil_cpp/absl/strings/string_view_benchmark.cc b/third_party/abseil_cpp/absl/strings/string_view_benchmark.cc deleted file mode 100644 index 0d74e23e2f..0000000000 --- a/third_party/abseil_cpp/absl/strings/string_view_benchmark.cc +++ /dev/null @@ -1,381 +0,0 @@ -// 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 -// -// https://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/string_view.h" - -#include <algorithm> -#include <cstdint> -#include <map> -#include <random> -#include <string> -#include <unordered_set> -#include <vector> - -#include "benchmark/benchmark.h" -#include "absl/base/attributes.h" -#include "absl/base/internal/raw_logging.h" -#include "absl/base/macros.h" -#include "absl/strings/str_cat.h" - -namespace { - -void BM_StringViewFromString(benchmark::State& state) { - std::string s(state.range(0), 'x'); - std::string* ps = &s; - struct SV { - SV() = default; - explicit SV(const std::string& s) : sv(s) {} - absl::string_view sv; - } sv; - SV* psv = &sv; - benchmark::DoNotOptimize(ps); - benchmark::DoNotOptimize(psv); - for (auto _ : state) { - new (psv) SV(*ps); - benchmark::DoNotOptimize(sv); - } -} -BENCHMARK(BM_StringViewFromString)->Arg(12)->Arg(128); - -// Provide a forcibly out-of-line wrapper for operator== that can be used in -// benchmarks to measure the impact of inlining. -ABSL_ATTRIBUTE_NOINLINE -bool NonInlinedEq(absl::string_view a, absl::string_view b) { return a == b; } - -// We use functions that cannot be inlined to perform the comparison loops so -// that inlining of the operator== can't optimize away *everything*. -ABSL_ATTRIBUTE_NOINLINE -void DoEqualityComparisons(benchmark::State& state, absl::string_view a, - absl::string_view b) { - for (auto _ : state) { - benchmark::DoNotOptimize(a == b); - } -} - -void BM_EqualIdentical(benchmark::State& state) { - std::string x(state.range(0), 'a'); - DoEqualityComparisons(state, x, x); -} -BENCHMARK(BM_EqualIdentical)->DenseRange(0, 3)->Range(4, 1 << 10); - -void BM_EqualSame(benchmark::State& state) { - std::string x(state.range(0), 'a'); - std::string y = x; - DoEqualityComparisons(state, x, y); -} -BENCHMARK(BM_EqualSame) - ->DenseRange(0, 10) - ->Arg(20) - ->Arg(40) - ->Arg(70) - ->Arg(110) - ->Range(160, 4096); - -void BM_EqualDifferent(benchmark::State& state) { - const int len = state.range(0); - std::string x(len, 'a'); - std::string y = x; - if (len > 0) { - y[len - 1] = 'b'; - } - DoEqualityComparisons(state, x, y); -} -BENCHMARK(BM_EqualDifferent)->DenseRange(0, 3)->Range(4, 1 << 10); - -// This benchmark is intended to check that important simplifications can be -// made with absl::string_view comparisons against constant strings. The idea is -// that if constant strings cause redundant components of the comparison, the -// compiler should detect and eliminate them. Here we use 8 different strings, -// each with the same size. Provided our comparison makes the implementation -// inline-able by the compiler, it should fold all of these away into a single -// size check once per loop iteration. -ABSL_ATTRIBUTE_NOINLINE -void DoConstantSizeInlinedEqualityComparisons(benchmark::State& state, - absl::string_view a) { - for (auto _ : state) { - benchmark::DoNotOptimize(a == "aaa"); - benchmark::DoNotOptimize(a == "bbb"); - benchmark::DoNotOptimize(a == "ccc"); - benchmark::DoNotOptimize(a == "ddd"); - benchmark::DoNotOptimize(a == "eee"); - benchmark::DoNotOptimize(a == "fff"); - benchmark::DoNotOptimize(a == "ggg"); - benchmark::DoNotOptimize(a == "hhh"); - } -} -void BM_EqualConstantSizeInlined(benchmark::State& state) { - std::string x(state.range(0), 'a'); - DoConstantSizeInlinedEqualityComparisons(state, x); -} -// We only need to check for size of 3, and <> 3 as this benchmark only has to -// do with size differences. -BENCHMARK(BM_EqualConstantSizeInlined)->DenseRange(2, 4); - -// This benchmark exists purely to give context to the above timings: this is -// what they would look like if the compiler is completely unable to simplify -// between two comparisons when they are comparing against constant strings. -ABSL_ATTRIBUTE_NOINLINE -void DoConstantSizeNonInlinedEqualityComparisons(benchmark::State& state, - absl::string_view a) { - for (auto _ : state) { - // Force these out-of-line to compare with the above function. - benchmark::DoNotOptimize(NonInlinedEq(a, "aaa")); - benchmark::DoNotOptimize(NonInlinedEq(a, "bbb")); - benchmark::DoNotOptimize(NonInlinedEq(a, "ccc")); - benchmark::DoNotOptimize(NonInlinedEq(a, "ddd")); - benchmark::DoNotOptimize(NonInlinedEq(a, "eee")); - benchmark::DoNotOptimize(NonInlinedEq(a, "fff")); - benchmark::DoNotOptimize(NonInlinedEq(a, "ggg")); - benchmark::DoNotOptimize(NonInlinedEq(a, "hhh")); - } -} - -void BM_EqualConstantSizeNonInlined(benchmark::State& state) { - std::string x(state.range(0), 'a'); - DoConstantSizeNonInlinedEqualityComparisons(state, x); -} -// We only need to check for size of 3, and <> 3 as this benchmark only has to -// do with size differences. -BENCHMARK(BM_EqualConstantSizeNonInlined)->DenseRange(2, 4); - -void BM_CompareSame(benchmark::State& state) { - const int len = state.range(0); - std::string x; - for (int i = 0; i < len; i++) { - x += 'a'; - } - std::string y = x; - absl::string_view a = x; - absl::string_view b = y; - - for (auto _ : state) { - benchmark::DoNotOptimize(a); - benchmark::DoNotOptimize(b); - benchmark::DoNotOptimize(a.compare(b)); - } -} -BENCHMARK(BM_CompareSame)->DenseRange(0, 3)->Range(4, 1 << 10); - -void BM_CompareFirstOneLess(benchmark::State& state) { - const int len = state.range(0); - std::string x(len, 'a'); - std::string y = x; - y.back() = 'b'; - absl::string_view a = x; - absl::string_view b = y; - - for (auto _ : state) { - benchmark::DoNotOptimize(a); - benchmark::DoNotOptimize(b); - benchmark::DoNotOptimize(a.compare(b)); - } -} -BENCHMARK(BM_CompareFirstOneLess)->DenseRange(1, 3)->Range(4, 1 << 10); - -void BM_CompareSecondOneLess(benchmark::State& state) { - const int len = state.range(0); - std::string x(len, 'a'); - std::string y = x; - x.back() = 'b'; - absl::string_view a = x; - absl::string_view b = y; - - for (auto _ : state) { - benchmark::DoNotOptimize(a); - benchmark::DoNotOptimize(b); - benchmark::DoNotOptimize(a.compare(b)); - } -} -BENCHMARK(BM_CompareSecondOneLess)->DenseRange(1, 3)->Range(4, 1 << 10); - -void BM_find_string_view_len_one(benchmark::State& state) { - std::string haystack(state.range(0), '0'); - absl::string_view s(haystack); - for (auto _ : state) { - benchmark::DoNotOptimize(s.find("x")); // not present; length 1 - } -} -BENCHMARK(BM_find_string_view_len_one)->Range(1, 1 << 20); - -void BM_find_string_view_len_two(benchmark::State& state) { - std::string haystack(state.range(0), '0'); - absl::string_view s(haystack); - for (auto _ : state) { - benchmark::DoNotOptimize(s.find("xx")); // not present; length 2 - } -} -BENCHMARK(BM_find_string_view_len_two)->Range(1, 1 << 20); - -void BM_find_one_char(benchmark::State& state) { - std::string haystack(state.range(0), '0'); - absl::string_view s(haystack); - for (auto _ : state) { - benchmark::DoNotOptimize(s.find('x')); // not present - } -} -BENCHMARK(BM_find_one_char)->Range(1, 1 << 20); - -void BM_rfind_one_char(benchmark::State& state) { - std::string haystack(state.range(0), '0'); - absl::string_view s(haystack); - for (auto _ : state) { - benchmark::DoNotOptimize(s.rfind('x')); // not present - } -} -BENCHMARK(BM_rfind_one_char)->Range(1, 1 << 20); - -void BM_worst_case_find_first_of(benchmark::State& state, int haystack_len) { - const int needle_len = state.range(0); - std::string needle; - for (int i = 0; i < needle_len; ++i) { - needle += 'a' + i; - } - std::string haystack(haystack_len, '0'); // 1000 zeros. - - absl::string_view s(haystack); - for (auto _ : state) { - benchmark::DoNotOptimize(s.find_first_of(needle)); - } -} - -void BM_find_first_of_short(benchmark::State& state) { - BM_worst_case_find_first_of(state, 10); -} - -void BM_find_first_of_medium(benchmark::State& state) { - BM_worst_case_find_first_of(state, 100); -} - -void BM_find_first_of_long(benchmark::State& state) { - BM_worst_case_find_first_of(state, 1000); -} - -BENCHMARK(BM_find_first_of_short)->DenseRange(0, 4)->Arg(8)->Arg(16)->Arg(32); -BENCHMARK(BM_find_first_of_medium)->DenseRange(0, 4)->Arg(8)->Arg(16)->Arg(32); -BENCHMARK(BM_find_first_of_long)->DenseRange(0, 4)->Arg(8)->Arg(16)->Arg(32); - -struct EasyMap : public std::map<absl::string_view, uint64_t> { - explicit EasyMap(size_t) {} -}; - -// This templated benchmark helper function is intended to stress operator== or -// operator< in a realistic test. It surely isn't entirely realistic, but it's -// a start. The test creates a map of type Map, a template arg, and populates -// it with table_size key/value pairs. Each key has WordsPerKey words. After -// creating the map, a number of lookups are done in random order. Some keys -// are used much more frequently than others in this phase of the test. -template <typename Map, int WordsPerKey> -void StringViewMapBenchmark(benchmark::State& state) { - const int table_size = state.range(0); - const double kFractionOfKeysThatAreHot = 0.2; - const int kNumLookupsOfHotKeys = 20; - const int kNumLookupsOfColdKeys = 1; - const char* words[] = {"the", "quick", "brown", "fox", "jumped", - "over", "the", "lazy", "dog", "and", - "found", "a", "large", "mushroom", "and", - "a", "couple", "crickets", "eating", "pie"}; - // Create some keys that consist of words in random order. - std::random_device r; - std::seed_seq seed({r(), r(), r(), r(), r(), r(), r(), r()}); - std::mt19937 rng(seed); - std::vector<std::string> keys(table_size); - std::vector<int> all_indices; - const int kBlockSize = 1 << 12; - std::unordered_set<std::string> t(kBlockSize); - std::uniform_int_distribution<int> uniform(0, ABSL_ARRAYSIZE(words) - 1); - for (int i = 0; i < table_size; i++) { - all_indices.push_back(i); - do { - keys[i].clear(); - for (int j = 0; j < WordsPerKey; j++) { - absl::StrAppend(&keys[i], j > 0 ? " " : "", words[uniform(rng)]); - } - } while (!t.insert(keys[i]).second); - } - - // Create a list of strings to lookup: a permutation of the array of - // keys we just created, with repeats. "Hot" keys get repeated more. - std::shuffle(all_indices.begin(), all_indices.end(), rng); - const int num_hot = table_size * kFractionOfKeysThatAreHot; - const int num_cold = table_size - num_hot; - std::vector<int> hot_indices(all_indices.begin(), - all_indices.begin() + num_hot); - std::vector<int> indices; - for (int i = 0; i < kNumLookupsOfColdKeys; i++) { - indices.insert(indices.end(), all_indices.begin(), all_indices.end()); - } - for (int i = 0; i < kNumLookupsOfHotKeys - kNumLookupsOfColdKeys; i++) { - indices.insert(indices.end(), hot_indices.begin(), hot_indices.end()); - } - std::shuffle(indices.begin(), indices.end(), rng); - ABSL_RAW_CHECK( - num_cold * kNumLookupsOfColdKeys + num_hot * kNumLookupsOfHotKeys == - indices.size(), - ""); - // After constructing the array we probe it with absl::string_views built from - // test_strings. This means operator== won't see equal pointers, so - // it'll have to check for equal lengths and equal characters. - std::vector<std::string> test_strings(indices.size()); - for (int i = 0; i < indices.size(); i++) { - test_strings[i] = keys[indices[i]]; - } - - // Run the benchmark. It includes map construction but is mostly - // map lookups. - for (auto _ : state) { - Map h(table_size); - for (int i = 0; i < table_size; i++) { - h[keys[i]] = i * 2; - } - ABSL_RAW_CHECK(h.size() == table_size, ""); - uint64_t sum = 0; - for (int i = 0; i < indices.size(); i++) { - sum += h[test_strings[i]]; - } - benchmark::DoNotOptimize(sum); - } -} - -void BM_StdMap_4(benchmark::State& state) { - StringViewMapBenchmark<EasyMap, 4>(state); -} -BENCHMARK(BM_StdMap_4)->Range(1 << 10, 1 << 16); - -void BM_StdMap_8(benchmark::State& state) { - StringViewMapBenchmark<EasyMap, 8>(state); -} -BENCHMARK(BM_StdMap_8)->Range(1 << 10, 1 << 16); - -void BM_CopyToStringNative(benchmark::State& state) { - std::string src(state.range(0), 'x'); - absl::string_view sv(src); - std::string dst; - for (auto _ : state) { - dst.assign(sv.begin(), sv.end()); - } -} -BENCHMARK(BM_CopyToStringNative)->Range(1 << 3, 1 << 12); - -void BM_AppendToStringNative(benchmark::State& state) { - std::string src(state.range(0), 'x'); - absl::string_view sv(src); - std::string dst; - for (auto _ : state) { - dst.clear(); - dst.insert(dst.end(), sv.begin(), sv.end()); - } -} -BENCHMARK(BM_AppendToStringNative)->Range(1 << 3, 1 << 12); - -} // namespace |