Refactor tests

Author: winner245

libcxx/docs/ReleaseNotes/20.rst

@@ -69,8 +69,9 @@ Improvements and New Features
 - The ``_LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY`` ABI configuration was added, which allows storing valid bounds
   in ``std::array::iterator`` and detecting OOB accesses when the appropriate hardening mode is enabled.
 
-- The input iterator overload of `assign(_InputIterator, _InputIterator)` in `std::vector<_Tp, _Allocator>` has been 
-  optimized, resulting in a performance improvement of up to 3.7x.
+- The input iterator overload of `assign(_InputIterator, _InputIterator)` in `std::vector<_Tp, _Allocator>` has been
+  optimized, resulting in a performance improvement of up to 2x for trivial element types (e.g., `std::vector<int>`),
+  and up to 3.4x for non-trivial element types (e.g., `std::vector<std::vector<int>>`).
 
 Deprecations and Removals
 -------------------------

libcxx/test/benchmarks/ContainerBenchmarks.h

@@ -49,27 +49,11 @@ void BM_Assignment(benchmark::State& st, Container) {
   }
 }
 
-template <class Container,
-          class GenInputs,
-          typename std::enable_if<std::is_trivial<typename Container::value_type>::value>::type* = nullptr>
+template <std::size_t... sz, typename Container, typename GenInputs>
 void BM_AssignInputIterIter(benchmark::State& st, Container c, GenInputs gen) {
-  auto in = gen(st.range(1));
-  c.resize(st.range(0));
-  benchmark::DoNotOptimize(&in);
-  benchmark::DoNotOptimize(&c);
-  for (auto _ : st) {
-    c.assign(cpp17_input_iterator(in.begin()), cpp17_input_iterator(in.end()));
-    benchmark::ClobberMemory();
-  }
-}
-
-template <class Container,
-          class GenInputs,
-          typename std::enable_if<!std::is_trivial<typename Container::value_type>::value>::type* = nullptr>
-void BM_AssignInputIterIter(benchmark::State& st, Container c, GenInputs gen) {
-  auto v = gen(1, 100);
+  auto v = gen(1, sz...);
   c.resize(st.range(0), v[0]);
-  auto in = gen(st.range(1), 32);
+  auto in = gen(st.range(1), sz...);
   benchmark::DoNotOptimize(&in);
   benchmark::DoNotOptimize(&c);
   for (auto _ : st) {

libcxx/test/benchmarks/vector_operations.bench.cpp

@@ -72,11 +72,14 @@ BENCHMARK(bm_grow<std::deque<int>>);
 BENCHMARK_CAPTURE(BM_AssignInputIterIter, vector_int, std::vector<int>{}, getRandomIntegerInputs<int>)
     ->Args({TestNumInputs, TestNumInputs});
 
-BENCHMARK_CAPTURE(BM_AssignInputIterIter, vector_string, std::vector<std::string>{}, getRandomStringInputsWithLength)
+BENCHMARK_CAPTURE(
+    BM_AssignInputIterIter<32>, vector_string, std::vector<std::string>{}, getRandomStringInputsWithLength)
     ->Args({TestNumInputs, TestNumInputs});
 
-BENCHMARK_CAPTURE(
-    BM_AssignInputIterIter, vector_vector_int, std::vector<std::vector<int>>{}, getRandomIntegerInputsWithLength<int>)
+BENCHMARK_CAPTURE(BM_AssignInputIterIter<100>,
+                  vector_vector_int,
+                  std::vector<std::vector<int>>{},
+                  getRandomIntegerInputsWithLength<int>)
     ->Args({TestNumInputs, TestNumInputs});
 
 BENCHMARK_MAIN();