[libc++][ranges] Add benchmarks for the `from_range` constructors of `vector` and `deque`.

[var-const]

Try to set the language version via set_target_properties instead of target_compile_options in case it works around the CMake issue on Windows.

[Mordante]

I would prefer to have the CMake changes in a separate patch. I'm happy with these changes after applying my suggestion.

libcxx/benchmarks/CMakeLists.txt

0–1

It seems I missed this hunk when I updated the CMake requirements. This version is now validated by the top-level script.

[var-const]

Rebase

[var-const]

Fix the CI

[var-const]

Fix CI

[var-const]

Rerun the Windows CI

[var-const]

Rebase.

[var-const]

Experiment to fix the CI

[Mordante]

LGTM after adding a comment.

libcxx/benchmarks/CMakeLists.txt

80

Please add a bit of comment here, once MSVC has cxx_std_23 support we should use that instead.

[var-const]

Address feedback

[var-const]

Address feedback

[sivachandra]

libcxx/benchmarks/CMakeLists.txt

87

This line seems to have taken down the runtimes sphinx docs builder: https://lab.llvm.org/buildbot/#/builders/242/builds/950

The builder seems to be using an old version of gcc which doesn't know about cxx_std_23. Could we perhaps skip benchmarks if we are using an old compiler?

[var-const]

libcxx/benchmarks/CMakeLists.txt

87

Hopefully https://github.com/llvm/llvm-zorg/pull/47 will fix that.

[sivachandra]

libcxx/benchmarks/CMakeLists.txt

87

Thanks. It needs a buildbot restart to take effect, which hopefully will happen soon enough.

libcxx/benchmarks/CMakeLists.txt

 include(ExternalProject)
 include(CheckCXXCompilerFlag)
 
 #==============================================================================
 # Build Google Benchmark for libc++
 #==============================================================================
 
 set(CMAKE_FOLDER "${CMAKE_FOLDER}/Benchmarks")
 

 # Benchmark tests configuration
 #==============================================================================
 add_custom_target(cxx-benchmarks)
 set(BENCHMARK_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR})
 set(BENCHMARK_LIBCXX_INSTALL ${CMAKE_CURRENT_BINARY_DIR}/benchmark-libcxx)
 set(BENCHMARK_NATIVE_INSTALL ${CMAKE_CURRENT_BINARY_DIR}/benchmark-native)
 
 add_library(               cxx-benchmarks-flags INTERFACE)
-target_compile_features(   cxx-benchmarks-flags INTERFACE cxx_std_20)
+#TODO(cmake): explicitly pass the `std:c++latest` flag on Windows to work around
+# an issue where requesting `cxx_std_23` results in an error -- somehow CMake
+# fails to translate the `c++23` flag into `c++latest`, and the highest numbered
+# C++ version that MSVC flags support is C++20.
+if (MSVC)
+  add_compile_options(/std:c++latest)
+else()
+  target_compile_features( cxx-benchmarks-flags INTERFACE cxx_std_23)
+endif()
 target_compile_options(    cxx-benchmarks-flags INTERFACE -fsized-deallocation -nostdinc++)
 target_include_directories(cxx-benchmarks-flags INTERFACE "${LIBCXX_GENERATED_INCLUDE_DIR}"
                                                 INTERFACE "${BENCHMARK_LIBCXX_INSTALL}/include"
                                                 INTERFACE "${LIBCXX_SOURCE_DIR}/test/support")
 
 add_library(           cxx-benchmarks-flags-native INTERFACE)
 target_link_libraries( cxx-benchmarks-flags-native INTERFACE cxx-benchmarks-flags)
 target_compile_options(cxx-benchmarks-flags-native INTERFACE ${BENCHMARK_NATIVE_TARGET_FLAGS})

libcxx/benchmarks/ContainerBenchmarks.h

void BM_ConstructIterIter(benchmark::State& st, Container, GenInputs gen) {
   benchmark::DoNotOptimize(&in);
   while (st.KeepRunning()) {
     Container c(begin, end);
     DoNotOptimizeData(c);
   }
 }
 
 template <class Container, class GenInputs>
+void BM_ConstructFromRange(benchmark::State& st, Container, GenInputs gen) {
+  auto in = gen(st.range(0));
+  benchmark::DoNotOptimize(&in);
+  while (st.KeepRunning()) {
+    Container c(std::from_range, in);
+    DoNotOptimizeData(c);
+  }
+}
+
+template <class Container, class GenInputs>
 void BM_InsertValue(benchmark::State& st, Container c, GenInputs gen) {
   auto in        = gen(st.range(0));
   const auto end = in.end();
   while (st.KeepRunning()) {
     c.clear();
     for (auto it = in.begin(); it != end; ++it) {
       benchmark::DoNotOptimize(&(*c.insert(*it).first));
     }

libcxx/benchmarks/deque.bench.cpp

BENCHMARK_CAPTURE(BM_ConstructIterIter, deque_char, std::deque<char>{}, getRandomIntegerInputs<char>)
     ->Arg(TestNumInputs);
 
 BENCHMARK_CAPTURE(BM_ConstructIterIter, deque_size_t, std::deque<size_t>{}, getRandomIntegerInputs<size_t>)
     ->Arg(TestNumInputs);
 
 BENCHMARK_CAPTURE(BM_ConstructIterIter, deque_string, std::deque<std::string>{}, getRandomStringInputs)
     ->Arg(TestNumInputs);
 
+BENCHMARK_CAPTURE(BM_ConstructFromRange, deque_char, std::deque<char>{}, getRandomIntegerInputs<char>)
+    ->Arg(TestNumInputs);
+
+BENCHMARK_CAPTURE(BM_ConstructFromRange, deque_size_t, std::deque<size_t>{}, getRandomIntegerInputs<size_t>)
+    ->Arg(TestNumInputs);
+
+BENCHMARK_CAPTURE(BM_ConstructFromRange, deque_string, std::deque<std::string>{}, getRandomStringInputs)
+    ->Arg(TestNumInputs);
+
 BENCHMARK_MAIN();

libcxx/benchmarks/vector_operations.bench.cpp

BENCHMARK_CAPTURE(BM_ConstructIterIter, vector_char, std::vector<char>{}, getRandomIntegerInputs<char>)
     ->Arg(TestNumInputs);
 
 BENCHMARK_CAPTURE(BM_ConstructIterIter, vector_size_t, std::vector<size_t>{}, getRandomIntegerInputs<size_t>)
     ->Arg(TestNumInputs);
 
 BENCHMARK_CAPTURE(BM_ConstructIterIter, vector_string, std::vector<std::string>{}, getRandomStringInputs)
     ->Arg(TestNumInputs);
 
+BENCHMARK_CAPTURE(BM_ConstructFromRange, vector_char, std::vector<char>{}, getRandomIntegerInputs<char>)
+    ->Arg(TestNumInputs);
+
+BENCHMARK_CAPTURE(BM_ConstructFromRange, vector_size_t, std::vector<size_t>{}, getRandomIntegerInputs<size_t>)
+    ->Arg(TestNumInputs);
+
+BENCHMARK_CAPTURE(BM_ConstructFromRange, vector_string, std::vector<std::string>{}, getRandomStringInputs)
+    ->Arg(TestNumInputs);
+
 BENCHMARK_MAIN();