[libcxx-commits] [libcxx] [libc++] Implement single element vector::insert in terms of emplace (PR #210284)

[Louis Dionne via libcxx-commits]

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@@ -227,6 +248,27 @@ void sequence_container_benchmarks(std::string container) {
           c.erase(c.end() - 1); // avoid growing indefinitely
         }
       });
+      bench("emplace(middle)" + tostr(gen), [gen](auto& st) {
+        auto const size = st.range(0);
+        std::vector<ValueType> in;
+        std::generate_n(std::back_inserter(in), size, gen);
+        DoNotOptimizeData(in);
+
+        Container c(in.begin(), in.end());
+        DoNotOptimizeData(c);
+
+        ValueType value = gen();
+        benchmark::DoNotOptimize(value);
+
+        for ([[maybe_unused]] auto _ : st) {
+          auto mid = c.begin() + (size / 2); // requires random-access iterators in order to make sense
+          c.emplace(mid, value);
+          DoNotOptimizeData(c);
+
+          c.erase(c.end() - 1); // avoid growing indefinitely
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ldionne wrote:

You could also simplify to use `pop_back`. If you do that, consider changing `insert` benchmarks as a drive-by.

https://github.com/llvm/llvm-project/pull/210284