about summary refs log tree commit diff
path: root/third_party/abseil_cpp/absl/strings/internal/memutil_benchmark.cc
diff options
context:
space:
mode:
Diffstat (limited to 'third_party/abseil_cpp/absl/strings/internal/memutil_benchmark.cc')
-rw-r--r--third_party/abseil_cpp/absl/strings/internal/memutil_benchmark.cc323
1 files changed, 0 insertions, 323 deletions
diff --git a/third_party/abseil_cpp/absl/strings/internal/memutil_benchmark.cc b/third_party/abseil_cpp/absl/strings/internal/memutil_benchmark.cc
deleted file mode 100644
index dc95c3e5e55a..000000000000
--- a/third_party/abseil_cpp/absl/strings/internal/memutil_benchmark.cc
+++ /dev/null
@@ -1,323 +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/internal/memutil.h"
-
-#include <algorithm>
-#include <cstdlib>
-
-#include "benchmark/benchmark.h"
-#include "absl/strings/ascii.h"
-
-// We fill the haystack with aaaaaaaaaaaaaaaaaa...aaaab.
-// That gives us:
-// - an easy search: 'b'
-// - a medium search: 'ab'.  That means every letter is a possible match.
-// - a pathological search: 'aaaaaa.......aaaaab' (half as many a's as haytack)
-// We benchmark case-sensitive and case-insensitive versions of
-// three memmem implementations:
-// - memmem() from memutil.h
-// - search() from STL
-// - memmatch(), a custom implementation using memchr and memcmp.
-// Here are sample results:
-//
-// Run on (12 X 3800 MHz CPU s)
-// CPU Caches:
-//   L1 Data 32K (x6)
-//   L1 Instruction 32K (x6)
-//   L2 Unified 256K (x6)
-//   L3 Unified 15360K (x1)
-// ----------------------------------------------------------------
-// Benchmark                           Time          CPU Iterations
-// ----------------------------------------------------------------
-// BM_Memmem                        3583 ns      3582 ns     196469  2.59966GB/s
-// BM_MemmemMedium                 13743 ns     13742 ns      50901  693.986MB/s
-// BM_MemmemPathological        13695030 ns  13693977 ns         51  713.133kB/s
-// BM_Memcasemem                    3299 ns      3299 ns     212942  2.82309GB/s
-// BM_MemcasememMedium             16407 ns     16406 ns      42170  581.309MB/s
-// BM_MemcasememPathological    17267745 ns  17266030 ns         41  565.598kB/s
-// BM_Search                        1610 ns      1609 ns     431321  5.78672GB/s
-// BM_SearchMedium                 11111 ns     11110 ns      63001  858.414MB/s
-// BM_SearchPathological        12117390 ns  12116397 ns         58  805.984kB/s
-// BM_Searchcase                    3081 ns      3081 ns     229949  3.02313GB/s
-// BM_SearchcaseMedium             16003 ns     16001 ns      44170  595.998MB/s
-// BM_SearchcasePathological    15823413 ns  15821909 ns         44  617.222kB/s
-// BM_Memmatch                       197 ns       197 ns    3584225  47.2951GB/s
-// BM_MemmatchMedium               52333 ns     52329 ns      13280  182.244MB/s
-// BM_MemmatchPathological        659799 ns    659727 ns       1058  14.4556MB/s
-// BM_Memcasematch                  5460 ns      5460 ns     127606  1.70586GB/s
-// BM_MemcasematchMedium           32861 ns     32857 ns      21258  290.248MB/s
-// BM_MemcasematchPathological  15154243 ns  15153089 ns         46  644.464kB/s
-// BM_MemmemStartup                    5 ns         5 ns  150821500
-// BM_SearchStartup                    5 ns         5 ns  150644203
-// BM_MemmatchStartup                  7 ns         7 ns   97068802
-//
-// Conclusions:
-//
-// The following recommendations are based on the sample results above. However,
-// we have found that the performance of STL search can vary significantly
-// depending on compiler and standard library implementation. We recommend you
-// run the benchmarks for yourself on relevant platforms.
-//
-// If you need case-insensitive, STL search is slightly better than memmem for
-// all cases.
-//
-// Case-sensitive is more subtle:
-// Custom memmatch is _very_ fast at scanning, so if you have very few possible
-// matches in your haystack, that's the way to go. Performance drops
-// significantly with more matches.
-//
-// STL search is slightly faster than memmem in the medium and pathological
-// benchmarks. However, the performance of memmem is currently more dependable
-// across platforms and build configurations.
-
-namespace {
-
-constexpr int kHaystackSize = 10000;
-constexpr int64_t kHaystackSize64 = kHaystackSize;
-const char* MakeHaystack() {
-  char* haystack = new char[kHaystackSize];
-  for (int i = 0; i < kHaystackSize - 1; ++i) haystack[i] = 'a';
-  haystack[kHaystackSize - 1] = 'b';
-  return haystack;
-}
-const char* const kHaystack = MakeHaystack();
-
-void BM_Memmem(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(
-        absl::strings_internal::memmem(kHaystack, kHaystackSize, "b", 1));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_Memmem);
-
-void BM_MemmemMedium(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(
-        absl::strings_internal::memmem(kHaystack, kHaystackSize, "ab", 2));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_MemmemMedium);
-
-void BM_MemmemPathological(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(absl::strings_internal::memmem(
-        kHaystack, kHaystackSize, kHaystack + kHaystackSize / 2,
-        kHaystackSize - kHaystackSize / 2));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_MemmemPathological);
-
-void BM_Memcasemem(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(
-        absl::strings_internal::memcasemem(kHaystack, kHaystackSize, "b", 1));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_Memcasemem);
-
-void BM_MemcasememMedium(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(
-        absl::strings_internal::memcasemem(kHaystack, kHaystackSize, "ab", 2));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_MemcasememMedium);
-
-void BM_MemcasememPathological(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(absl::strings_internal::memcasemem(
-        kHaystack, kHaystackSize, kHaystack + kHaystackSize / 2,
-        kHaystackSize - kHaystackSize / 2));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_MemcasememPathological);
-
-bool case_eq(const char a, const char b) {
-  return absl::ascii_tolower(a) == absl::ascii_tolower(b);
-}
-
-void BM_Search(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(std::search(kHaystack, kHaystack + kHaystackSize,
-                                         kHaystack + kHaystackSize - 1,
-                                         kHaystack + kHaystackSize));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_Search);
-
-void BM_SearchMedium(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(std::search(kHaystack, kHaystack + kHaystackSize,
-                                         kHaystack + kHaystackSize - 2,
-                                         kHaystack + kHaystackSize));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_SearchMedium);
-
-void BM_SearchPathological(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(std::search(kHaystack, kHaystack + kHaystackSize,
-                                         kHaystack + kHaystackSize / 2,
-                                         kHaystack + kHaystackSize));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_SearchPathological);
-
-void BM_Searchcase(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(std::search(kHaystack, kHaystack + kHaystackSize,
-                                         kHaystack + kHaystackSize - 1,
-                                         kHaystack + kHaystackSize, case_eq));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_Searchcase);
-
-void BM_SearchcaseMedium(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(std::search(kHaystack, kHaystack + kHaystackSize,
-                                         kHaystack + kHaystackSize - 2,
-                                         kHaystack + kHaystackSize, case_eq));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_SearchcaseMedium);
-
-void BM_SearchcasePathological(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(std::search(kHaystack, kHaystack + kHaystackSize,
-                                         kHaystack + kHaystackSize / 2,
-                                         kHaystack + kHaystackSize, case_eq));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_SearchcasePathological);
-
-char* memcasechr(const char* s, int c, size_t slen) {
-  c = absl::ascii_tolower(c);
-  for (; slen; ++s, --slen) {
-    if (absl::ascii_tolower(*s) == c) return const_cast<char*>(s);
-  }
-  return nullptr;
-}
-
-const char* memcasematch(const char* phaystack, size_t haylen,
-                         const char* pneedle, size_t neelen) {
-  if (0 == neelen) {
-    return phaystack;  // even if haylen is 0
-  }
-  if (haylen < neelen) return nullptr;
-
-  const char* match;
-  const char* hayend = phaystack + haylen - neelen + 1;
-  while ((match = static_cast<char*>(
-              memcasechr(phaystack, pneedle[0], hayend - phaystack)))) {
-    if (absl::strings_internal::memcasecmp(match, pneedle, neelen) == 0)
-      return match;
-    else
-      phaystack = match + 1;
-  }
-  return nullptr;
-}
-
-void BM_Memmatch(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(
-        absl::strings_internal::memmatch(kHaystack, kHaystackSize, "b", 1));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_Memmatch);
-
-void BM_MemmatchMedium(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(
-        absl::strings_internal::memmatch(kHaystack, kHaystackSize, "ab", 2));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_MemmatchMedium);
-
-void BM_MemmatchPathological(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(absl::strings_internal::memmatch(
-        kHaystack, kHaystackSize, kHaystack + kHaystackSize / 2,
-        kHaystackSize - kHaystackSize / 2));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_MemmatchPathological);
-
-void BM_Memcasematch(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(memcasematch(kHaystack, kHaystackSize, "b", 1));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_Memcasematch);
-
-void BM_MemcasematchMedium(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(memcasematch(kHaystack, kHaystackSize, "ab", 2));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_MemcasematchMedium);
-
-void BM_MemcasematchPathological(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(memcasematch(kHaystack, kHaystackSize,
-                                          kHaystack + kHaystackSize / 2,
-                                          kHaystackSize - kHaystackSize / 2));
-  }
-  state.SetBytesProcessed(kHaystackSize64 * state.iterations());
-}
-BENCHMARK(BM_MemcasematchPathological);
-
-void BM_MemmemStartup(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(absl::strings_internal::memmem(
-        kHaystack + kHaystackSize - 10, 10, kHaystack + kHaystackSize - 1, 1));
-  }
-}
-BENCHMARK(BM_MemmemStartup);
-
-void BM_SearchStartup(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(
-        std::search(kHaystack + kHaystackSize - 10, kHaystack + kHaystackSize,
-                    kHaystack + kHaystackSize - 1, kHaystack + kHaystackSize));
-  }
-}
-BENCHMARK(BM_SearchStartup);
-
-void BM_MemmatchStartup(benchmark::State& state) {
-  for (auto _ : state) {
-    benchmark::DoNotOptimize(absl::strings_internal::memmatch(
-        kHaystack + kHaystackSize - 10, 10, kHaystack + kHaystackSize - 1, 1));
-  }
-}
-BENCHMARK(BM_MemmatchStartup);
-
-}  // namespace