1 files changed, 73 insertions, 0 deletions
diff --git a/abseil-cpp/absl/numeric/bits_benchmark.cc b/abseil-cpp/absl/numeric/bits_benchmark.cc
new file mode 100644
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--- /dev/null
+++ b/abseil-cpp/absl/numeric/bits_benchmark.cc
@@ -0,0 +1,73 @@
+// Copyright 2022 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 <cstdint>
+#include <vector>
+
+#include "benchmark/benchmark.h"
+#include "absl/base/optimization.h"
+#include "absl/numeric/bits.h"
+#include "absl/random/random.h"
+
+namespace absl {
+namespace {
+
+template <typename T>
+static void BM_bit_width(benchmark::State& state) {
+  const auto count = static_cast<size_t>(state.range(0));
+
+  absl::BitGen rng;
+  std::vector<T> values;
+  values.reserve(count);
+  for (size_t i = 0; i < count; ++i) {
+    values.push_back(absl::Uniform<T>(rng, 0, std::numeric_limits<T>::max()));
+  }
+
+  while (state.KeepRunningBatch(static_cast<int64_t>(count))) {
+    for (size_t i = 0; i < count; ++i) {
+      benchmark::DoNotOptimize(absl::bit_width(values[i]));
+    }
+  }
+}
+BENCHMARK_TEMPLATE(BM_bit_width, uint8_t)->Range(1, 1 << 20);
+BENCHMARK_TEMPLATE(BM_bit_width, uint16_t)->Range(1, 1 << 20);
+BENCHMARK_TEMPLATE(BM_bit_width, uint32_t)->Range(1, 1 << 20);
+BENCHMARK_TEMPLATE(BM_bit_width, uint64_t)->Range(1, 1 << 20);
+
+template <typename T>
+static void BM_bit_width_nonzero(benchmark::State& state) {
+  const auto count = static_cast<size_t>(state.range(0));
+
+  absl::BitGen rng;
+  std::vector<T> values;
+  values.reserve(count);
+  for (size_t i = 0; i < count; ++i) {
+    values.push_back(absl::Uniform<T>(rng, 1, std::numeric_limits<T>::max()));
+  }
+
+  while (state.KeepRunningBatch(static_cast<int64_t>(count))) {
+    for (size_t i = 0; i < count; ++i) {
+      const T value = values[i];
+      ABSL_ASSUME(value > 0);
+      benchmark::DoNotOptimize(absl::bit_width(value));
+    }
+  }
+}
+BENCHMARK_TEMPLATE(BM_bit_width_nonzero, uint8_t)->Range(1, 1 << 20);
+BENCHMARK_TEMPLATE(BM_bit_width_nonzero, uint16_t)->Range(1, 1 << 20);
+BENCHMARK_TEMPLATE(BM_bit_width_nonzero, uint32_t)->Range(1, 1 << 20);
+BENCHMARK_TEMPLATE(BM_bit_width_nonzero, uint64_t)->Range(1, 1 << 20);
+
+}  // namespace
+}  // namespace absl