[libcxx-commits] [libcxx] [libc++] Optimize __tree copy/move constructor/assignment with allocator (PR #163558)

[Nikolas Klauser via libcxx-commits]

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@@ -103,6 +107,61 @@ void associative_container_benchmarks(std::string container) {
     }
   });
 
+  bench("ctor(const&, alloc)", [=](auto& st) {
+    const std::size_t size = st.range(0);
+    std::vector<Value> in  = make_value_types(generate_unique_keys(size));
+    Container src(in.begin(), in.end());
+    ScratchSpace c[BatchSize];
+
+    while (st.KeepRunningBatch(BatchSize)) {
+      for (std::size_t i = 0; i != BatchSize; ++i) {
+        new (c + i) Container(src, typename std::allocator<typename Container::value_type>());
+        benchmark::DoNotOptimize(c + i);
+        benchmark::ClobberMemory();
+      }
+
+      st.PauseTiming();
+      for (std::size_t i = 0; i != BatchSize; ++i) {
+        reinterpret_cast<Container*>(c + i)->~Container();
+      }
+      st.ResumeTiming();
+    }
+  });
+
+  bench("ctor(&&, different allocs)", [=](auto& st) {
+    using PMRContainer = adapt_operations<Container>::template rebind_alloc<
+        std::pmr::polymorphic_allocator<typename Container::value_type>>;
+
+    const std::size_t size = st.range(0);
+    std::vector<Value> in  = make_value_types(generate_unique_keys(size));
+    std::pmr::monotonic_buffer_resource rs(524288 * 32);
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philnik777 wrote:

I'm not quite sure anymore how I got to this number. I've replaced it with something less magic which should be good enough.

https://github.com/llvm/llvm-project/pull/163558