- 07191b0f52301e1e4a790e236f7b7c2fd90561ae Disambiguates computed return type of absl::optional logi... by Abseil Team <absl-team@google.com>

  - acd95f8ec4e6ec1587cb198c7f40af3c81094d92 Release container benchmarks. by Alex Strelnikov <strel@google.com>
  - 80f596b6b7c5e06453e778c16527d5a0e85f8413 Allow absl::base_internal::AtomicHook to have a default v... by Derek Mauro <dmauro@google.com>
  - 8402631546af8bcbd4acdf897d0cdfb805ad544a Release thread_identity benchmark. by Alex Strelnikov <strel@google.com>
  - 6dcb1e90fefb8556ce4654983d3a73c7585b4b99 Fix spelling error in variant.h by Abseil Team <absl-team@google.com>
  - faa8a81e1442018c0d400b09a595a5be55074715 Run tests from CMake.  The CI is currently Linux only, fo... by Jon Cohen <cohenjon@google.com>
  - 745ed6db574f931f2ec3a88e964fb03a5f22f816 Internal change. by Derek Mauro <dmauro@google.com>
  - 23facd7d1c5f43ac8181b016ee4acc5955f048c1 absl::variant exception safety test. by Xiaoyi Zhang <zhangxy@google.com>
  - c18e21e7cf8f6e83ae9d90e536e886409dd6cf68 Reinstate the syntax check on time-zone abbreviations now... by Abseil Team <absl-team@google.com>
  - da469f4314f0c820665a2b5b9477af9462b23e42 Import CCTZ changes to internal copy. by Shaindel Schwartz <shaindel@google.com>
  - 44ea35843517be03ab256b69449ccfea64352621 Import CCTZ changes to internal copy. by Abseil Team <absl-team@google.com>
  - 55d1105312687c6093950fac831c7540f49045b5 Import CCTZ changes to internal copy. by Greg Falcon <gfalcon@google.com>
  - 58d7965ad274406410b6d833213eca04d41c6867 Add zoneinfo as a data dependency to the //absl/time tests. by Shaindel Schwartz <shaindel@google.com>
  - 6acc50146f9ff29015bfaaa5bf9900691f839da5 Change benchmark target type from cc_test to cc_binary. by Alex Strelnikov <strel@google.com>
  - db3fbdae8f9f285a466f7a070326b1ce43b6a0dd Update WORKSPACE for C++ microbenchmarks and release algo... by Alex Strelnikov <strel@google.com>
  - 0869ae168255242af651853ed01719166d8cebf6 Update to Bazel version 0.13.0. by Abseil Team <absl-team@google.com>
  - e507dd53ab788964207fdf27d31b72a33c296fab Add missing include of cstdio by Abseil Team <absl-team@google.com>

GitOrigin-RevId: 07191b0f52301e1e4a790e236f7b7c2fd90561ae
Change-Id: I90994cf2b438fbec894724dcd9b90882281eef56

2 files changed, 140 insertions, 0 deletions

diff --git a/absl/algorithm/BUILD.bazel b/absl/algorithm/BUILD.bazel
index 255b986e..5cd54960 100644
--- a/absl/algorithm/BUILD.bazel
+++ b/absl/algorithm/BUILD.bazel
@@ -41,6 +41,18 @@ cc_test(
     ],
 )
 
+cc_binary(
+    name = "algorithm_benchmark",
+    testonly = 1,
+    srcs = ["equal_benchmark.cc"],
+    copts = ABSL_TEST_COPTS,
+    deps = [
+        ":algorithm",
+        "//absl/base:core_headers",
+        "@com_github_google_benchmark//:benchmark",
+    ],
+)
+
 cc_library(
     name = "container",
     hdrs = [
diff --git a/absl/algorithm/equal_benchmark.cc b/absl/algorithm/equal_benchmark.cc
new file mode 100644
index 00000000..fea6d137
--- /dev/null
+++ b/absl/algorithm/equal_benchmark.cc
@@ -0,0 +1,128 @@
+// 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();