Add has_single_bit benchmark

Author: pps83

benchmarks/CMakeLists.txt

@@ -114,6 +114,7 @@ add_benchmark(efficient_nonlocking_print src/efficient_nonlocking_print.cpp)
 add_benchmark(filesystem src/filesystem.cpp)
 add_benchmark(find_and_count src/find_and_count.cpp)
 add_benchmark(find_first_of src/find_first_of.cpp)
+add_benchmark(has_single_bit src/has_single_bit.cpp)
 add_benchmark(iota src/iota.cpp)
 add_benchmark(locale_classic src/locale_classic.cpp)
 add_benchmark(minmax_element src/minmax_element.cpp)

benchmarks/src/has_single_bit.cpp

@@ -0,0 +1,51 @@
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include <assert.h>
+#include <benchmark/benchmark.h>
+#include <bit>
+
+#include <utility.hpp>
+
+template <typename T>
+static void has_single_bit_if(benchmark::State& state) {
+    const auto random_v = random_vector<T>(8);
+    for (auto _ : state) {
+        benchmark::DoNotOptimize(random_v);
+        int count_true = 0, count_false = 0;
+        for (const auto& x : random_v) {
+            if (std::has_single_bit(x)) {
+                benchmark::DoNotOptimize(count_true++);
+            } else {
+                benchmark::DoNotOptimize(count_false++);
+            }
+        }
+    }
+}
+
+template <typename T>
+static void has_single_bit(benchmark::State& state) {
+    const auto random_v = random_vector<T>(8);
+    assert(random_v.size() % 4 == 0);
+    for (auto _ : state) {
+        benchmark::DoNotOptimize(random_v);
+        int r = 0, count_false = 0;
+        for (size_t i = 0; i < random_v.size(); i += 4) {
+            r += std::has_single_bit(random_v[i + 0]);
+            r += std::has_single_bit(random_v[i + 1]);
+            r += std::has_single_bit(random_v[i + 2]);
+            r += std::has_single_bit(random_v[i + 3]);
+        }
+        benchmark::DoNotOptimize(r);
+    }
+}
+
+BENCHMARK(has_single_bit_if<uint16_t>);
+BENCHMARK(has_single_bit_if<uint32_t>);
+BENCHMARK(has_single_bit_if<uint64_t>);
+
+BENCHMARK(has_single_bit<uint16_t>);
+BENCHMARK(has_single_bit<uint32_t>);
+BENCHMARK(has_single_bit<uint64_t>);
+
+BENCHMARK_MAIN();