[libcxx-commits] [libcxx] [libc++] Add benchmarks for std::is_heap and std::is_heap_until (PR #207045)

[Nikolas Klauser via libcxx-commits]

================
@@ -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 <string>
+#include <vector>
+
+#include "benchmark/benchmark.h"
+#include "../../GenerateInput.h"
+
+int main(int argc, char** argv) {
+  auto std_is_heap      = [](auto first, auto last) { return std::is_heap(first, last); };
+  auto std_is_heap_pred = [](auto first, auto last) {
+    return std::is_heap(first, last, [](auto x, auto y) {
+      benchmark::DoNotOptimize(x);
+      benchmark::DoNotOptimize(y);
+      return x < y;
+    });
+  };
+  auto std_is_heap_until      = [](auto first, auto last) { return std::is_heap_until(first, last); };
+  auto std_is_heap_until_pred = [](auto first, auto last) {
+    return std::is_heap_until(first, last, [](auto x, auto y) {
+      benchmark::DoNotOptimize(x);
+      benchmark::DoNotOptimize(y);
+      return x < y;
+    });
+  };
+
+  // Benchmark {std,ranges}::{is_heap,is_heap_until} on a valid heap. This is the worst case since the
+  // whole range must be scanned before we can conclude the heap invariant holds.
+  {
+    auto bm = []<class Container>(std::string name, auto is_heap) {
+      benchmark::RegisterBenchmark(
+          name,
+          [is_heap](auto& st) {
+            std::size_t const size = st.range(0);
+            using ValueType        = typename Container::value_type;
+            std::vector<ValueType> data;
+            std::generate_n(std::back_inserter(data), size, [] { return Generate<ValueType>::random(); });
+            std::make_heap(data.begin(), data.end());
+
+            Container c(data.begin(), data.end());
+
+            for ([[maybe_unused]] auto _ : st) {
----------------
philnik777 wrote:

```suggestion
            for (auto _ : st) {
```
I don't think this will be diagnosed.

https://github.com/llvm/llvm-project/pull/207045