[libc++] Add benchmarks for copy algorithms (llvm#127328)

This patch adds benchmarks for the copy family of algorithms (copy,
copy_n, copy_if, copy_backward).

Author: ldionne

libcxx/test/benchmarks/algorithms/copy.bench.cpp

@@ -0,0 +1,83 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+
+#include <algorithm>
+#include <cstddef>
+#include <deque>
+#include <iterator>
+#include <list>
+#include <string>
+#include <vector>
+
+#include "benchmark/benchmark.h"
+#include "../../GenerateInput.h"
+#include "test_macros.h"
+
+int main(int argc, char** argv) {
+  auto std_copy = [](auto first, auto last, auto out) { return std::copy(first, last, out); };
+
+  // {std,ranges}::copy(normal container)
+  {
+    auto bm = []<class Container>(std::string name, auto copy) {
+      benchmark::RegisterBenchmark(name, [copy](auto& st) {
+        std::size_t const n = st.range(0);
+        using ValueType     = typename Container::value_type;
+        Container c;
+        std::generate_n(std::back_inserter(c), n, [] { return Generate<ValueType>::random(); });
+
+        std::vector<ValueType> out(n);
+
+        for ([[maybe_unused]] auto _ : st) {
+          benchmark::DoNotOptimize(c);
+          benchmark::DoNotOptimize(out);
+          auto result = copy(c.begin(), c.end(), out.begin());
+          benchmark::DoNotOptimize(result);
+        }
+      })->Range(8, 1 << 20);
+    };
+    bm.operator()<std::vector<int>>("std::copy(vector<int>)", std_copy);
+    bm.operator()<std::deque<int>>("std::copy(deque<int>)", std_copy);
+    bm.operator()<std::list<int>>("std::copy(list<int>)", std_copy);
+    bm.operator()<std::vector<int>>("rng::copy(vector<int>)", std::ranges::copy);
+    bm.operator()<std::deque<int>>("rng::copy(deque<int>)", std::ranges::copy);
+    bm.operator()<std::list<int>>("rng::copy(list<int>)", std::ranges::copy);
+  }
+
+  // {std,ranges}::copy(vector<bool>)
+  {
+    auto bm = []<bool Aligned>(std::string name, auto copy) {
+      benchmark::RegisterBenchmark(name, [copy](auto& st) {
+        std::size_t const n = st.range(0);
+        std::vector<bool> in(n, true);
+        std::vector<bool> out(Aligned ? n : n + 8);
+        auto first = in.begin();
+        auto last  = in.end();
+        auto dst   = Aligned ? out.begin() : out.begin() + 4;
+        for ([[maybe_unused]] auto _ : st) {
+          benchmark::DoNotOptimize(in);
+          benchmark::DoNotOptimize(out);
+          auto result = copy(first, last, dst);
+          benchmark::DoNotOptimize(result);
+        }
+      })->Range(64, 1 << 20);
+    };
+    bm.operator()<true>("std::copy(vector<bool>) (aligned)", std_copy);
+    bm.operator()<false>("std::copy(vector<bool>) (unaligned)", std_copy);
+#if TEST_STD_VER >= 23 // vector<bool>::iterator is not an output_iterator before C++23
+    bm.operator()<true>("rng::copy(vector<bool>) (aligned)", std::ranges::copy);
+    bm.operator()<false>("rng::copy(vector<bool>) (unaligned)", std::ranges::copy);
+#endif
+  }
+
+  benchmark::Initialize(&argc, argv);
+  benchmark::RunSpecifiedBenchmarks();
+  benchmark::Shutdown();
+  return 0;
+}

libcxx/test/benchmarks/algorithms/copy_backward.bench.cpp

@@ -0,0 +1,84 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+
+#include <algorithm>
+#include <cstddef>
+#include <deque>
+#include <iterator>
+#include <list>
+#include <string>
+#include <vector>
+
+#include "benchmark/benchmark.h"
+#include "../../GenerateInput.h"
+#include "test_macros.h"
+
+int main(int argc, char** argv) {
+  auto std_copy_backward = [](auto first, auto last, auto out) { return std::copy_backward(first, last, out); };
+
+  // {std,ranges}::copy_n(normal container)
+  {
+    auto bm = []<class Container>(std::string name, auto copy_backward) {
+      benchmark::RegisterBenchmark(name, [copy_backward](auto& st) {
+        std::size_t const n = st.range(0);
+        using ValueType     = typename Container::value_type;
+        Container c;
+        std::generate_n(std::back_inserter(c), n, [] { return Generate<ValueType>::random(); });
+
+        std::vector<ValueType> out(n);
+
+        for ([[maybe_unused]] auto _ : st) {
+          benchmark::DoNotOptimize(c);
+          benchmark::DoNotOptimize(out);
+          auto result = copy_backward(c.begin(), c.end(), out.end());
+          benchmark::DoNotOptimize(result);
+        }
+      })->Range(8, 1 << 20);
+    };
+    bm.operator()<std::vector<int>>("std::copy_backward(vector<int>)", std_copy_backward);
+    bm.operator()<std::deque<int>>("std::copy_backward(deque<int>)", std_copy_backward);
+    bm.operator()<std::list<int>>("std::copy_backward(list<int>)", std_copy_backward);
+    bm.operator()<std::vector<int>>("rng::copy_backward(vector<int>)", std::ranges::copy_backward);
+    bm.operator()<std::deque<int>>("rng::copy_backward(deque<int>)", std::ranges::copy_backward);
+    bm.operator()<std::list<int>>("rng::copy_backward(list<int>)", std::ranges::copy_backward);
+  }
+
+  // {std,ranges}::copy_n(vector<bool>)
+  {
+    auto bm = []<bool Aligned>(std::string name, auto copy_backward) {
+      benchmark::RegisterBenchmark(name, [copy_backward](auto& st) {
+        std::size_t const n = st.range(0);
+        std::vector<bool> in(n, true);
+        std::vector<bool> out(Aligned ? n : n + 8);
+        benchmark::DoNotOptimize(&in);
+        auto first = in.begin();
+        auto last  = in.end();
+        auto dst   = Aligned ? out.end() : out.end() - 4;
+        for ([[maybe_unused]] auto _ : st) {
+          benchmark::DoNotOptimize(in);
+          benchmark::DoNotOptimize(out);
+          auto result = copy_backward(first, last, dst);
+          benchmark::DoNotOptimize(result);
+        }
+      })->Range(64, 1 << 20);
+    };
+    bm.operator()<true>("std::copy_backward(vector<bool>) (aligned)", std_copy_backward);
+    bm.operator()<false>("std::copy_backward(vector<bool>) (unaligned)", std_copy_backward);
+#if TEST_STD_VER >= 23 // vector<bool>::iterator is not an output_iterator before C++23
+    bm.operator()<true>("rng::copy_backward(vector<bool>) (aligned)", std::ranges::copy_backward);
+    bm.operator()<false>("rng::copy_backward(vector<bool>) (unaligned)", std::ranges::copy_backward);
+#endif
+  }
+
+  benchmark::Initialize(&argc, argv);
+  benchmark::RunSpecifiedBenchmarks();
+  benchmark::Shutdown();
+  return 0;
+}