Cleanup `//absl/strings/internal/memutil.h`

`memmatch()` is only used in `string_view.cc`, so move it there.
The moving of `memmatch()` to `string_view.cc` decouples `string_view`
from `memutil`, which will allow us to move `string_view` into its
own target in a followup.

The only other function that is used is `memcasecmp()`, so delete
all other functions.

PiperOrigin-RevId: 547238386
Change-Id: Id6fad47dd24191c8e8f26dd923fffa1007c8db4a

1 files changed, 0 insertions, 195 deletions

diff --git a/absl/strings/internal/memutil_benchmark.cc b/absl/strings/internal/memutil_benchmark.cc
index dc95c3e5..61e323a4 100644
--- a/absl/strings/internal/memutil_benchmark.cc
+++ b/absl/strings/internal/memutil_benchmark.cc
@@ -25,62 +25,6 @@
 // - 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 {
 
@@ -94,96 +38,10 @@ const char* MakeHaystack() {
 }
 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,
@@ -241,34 +99,6 @@ const char* memcasematch(const char* phaystack, size_t haylen,
   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));
@@ -295,29 +125,4 @@ void BM_MemcasematchPathological(benchmark::State& state) {
 }
 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