Add sal\sar benchmarks (#3)

Author: ttldtor

CMakeLists.txt

@@ -4,6 +4,9 @@
 cmake_minimum_required(VERSION 3.16)
 project(bits VERSION 0.1.0 LANGUAGES CXX)
 
+set(CMAKE_CXX_STANDARD 20)
+set(CXX_EXTENSIONS OFF)
+
 add_library(bits INTERFACE)
 add_library(bits::bits ALIAS bits)
 add_library(org::ttldtor::bits::bits ALIAS bits)

tests/CMakeLists.txt

@@ -3,21 +3,26 @@
 
 include(FetchContent)
 FetchContent_Declare(
-    doctest
-    GIT_REPOSITORY https://github.com/doctest/doctest.git
-    GIT_TAG v2.4.12)
+        doctest
+        GIT_REPOSITORY https://github.com/doctest/doctest.git
+        GIT_TAG v2.4.12)
 FetchContent_MakeAvailable(doctest)
 
 FetchContent_Declare(
-    nanobench
-    GIT_REPOSITORY https://github.com/martinus/nanobench.git
-    GIT_TAG v4.1.0
-    GIT_SHALLOW TRUE)
+        nanobench
+        GIT_REPOSITORY https://github.com/martinus/nanobench.git
+        GIT_TAG v4.1.0
+        GIT_SHALLOW TRUE)
 FetchContent_MakeAvailable(nanobench)
 
 add_executable(bits_tests
-    main.cpp
-    bits.cpp
+        main.cpp
+        bits.cpp
+)
+
+set_target_properties(bits_tests PROPERTIES
+        CXX_STANDARD 20
+        CXX_EXTENSIONS OFF
 )
 
 target_link_libraries(bits_tests PRIVATE bits::bits)
@@ -30,7 +35,22 @@ add_executable(bits_bench
         bench.cpp
 )
 
+set_target_properties(bits_bench PROPERTIES
+        CXX_STANDARD 20
+        CXX_EXTENSIONS OFF
+)
+
 target_link_libraries(bits_bench PRIVATE bits::bits nanobench)
 target_include_directories(bits_bench PRIVATE ${doctest_SOURCE_DIR})
 
-add_test(NAME bits_bench COMMAND bits_bench)
+if (CMAKE_CONFIGURATION_TYPES)
+    set_property(TARGET bits_bench PROPERTY EXCLUDE_FROM_DEFAULT_BUILD_Debug TRUE)
+    add_test(NAME bits_bench COMMAND bits_bench)
+    set_tests_properties(bits_bench PROPERTIES DISABLED "$<CONFIG:Debug>")
+else ()
+    if (CMAKE_BUILD_TYPE STREQUAL "Release")
+        add_test(NAME bits_bench COMMAND bits_bench)
+    else ()
+        set_property(TARGET bits_bench PROPERTY EXCLUDE_FROM_ALL TRUE)
+    endif ()
+endif ()

tests/bench.cpp

@@ -12,12 +12,107 @@
 #include <limits>
 
 using namespace org::ttldtor::bits;
+using namespace std::literals;
 
 // NOLINTNEXTLINE
 
-TEST_CASE("tutorial_fast_v2") {
-  uint64_t x = 1;
-  ankerl::nanobench::Bench().run("++x", [&]() {
-    ankerl::nanobench::doNotOptimizeAway(x += 1);
-  });
+TEST_CASE("bench_sal_sar_vs_builtin") {
+  constexpr size_t N = 1u << 15;
+
+  std::mt19937_64 rng{0xB00B00};
+  // For comparison with builtin << we use unsigned types and non-negative shifts
+  std::uniform_int_distribution<uint32_t> u32dist{0u, 0x7FFF'FFFFu};
+  std::uniform_int_distribution<uint64_t> u64dist{0ull, (1ull << 50)};
+  std::uniform_int_distribution<unsigned> shldist{0u, 63u};
+
+  // For comparison with builtin >> we use signed types and non-negative shifts
+  std::uniform_int_distribution<int32_t> s32dist{-(1 << 29), (1 << 29)};
+  std::uniform_int_distribution<int64_t> s64dist{-(1ll << 50), (1ll << 50)};
+  std::uniform_int_distribution<unsigned> shrdist{0u, 63u};
+
+  std::vector<uint32_t> u32(N);
+  std::vector<unsigned> shl32(N);
+  std::vector<uint64_t> u64(N);
+  std::vector<unsigned> shl64(N);
+
+  std::vector<int32_t> s32(N);
+  std::vector<unsigned> shr32(N);
+  std::vector<int64_t> s64(N);
+  std::vector<unsigned> shr64(N);
+
+  for (size_t i = 0; i < N; ++i) {
+    u32[i] = u32dist(rng);
+    shl32[i] = shldist(rng) % 32;
+    u64[i] = u64dist(rng);
+    shl64[i] = shldist(rng) % 64;
+
+    s32[i] = s32dist(rng);
+    shr32[i] = shrdist(rng) % 32;
+    s64[i] = s64dist(rng);
+    shr64[i] = shrdist(rng) % 64;
+  }
+
+  auto createBench = [&](auto title) {
+    ankerl::nanobench::Bench bench;
+
+    bench.title(title)
+      .unit("op")
+      .batch(N)
+      .warmup(100)
+      .minEpochTime(150ms)
+      .minEpochIterations(60000)
+      .relative(true)
+      .performanceCounters(true);
+
+    return bench;
+  };
+
+  auto runSalBench = [&](auto& bench, const auto& typeName, const auto& values, const auto& shifts) {
+    bench.run("builtin << ("s + typeName + ")", [&] {
+      uint32_t acc = 0;
+      for (size_t i = 0; i < N; ++i) {
+        acc ^= values[i] << shifts[i];
+      }
+      ankerl::nanobench::doNotOptimizeAway(acc);
+    });
+
+    bench.run("sal<"s + typeName + ">", [&] {
+      uint32_t acc = 0;
+      for (size_t i = 0; i < N; ++i) {
+        acc ^= sal(values[i], shifts[i]);
+      }
+      ankerl::nanobench::doNotOptimizeAway(acc);
+    });
+  };
+
+
+  auto runSarBench = [&](auto& bench, const auto& typeName, const auto& values, const auto& shifts) {
+    bench.run("builtin >> ("s + typeName + ")", [&] {
+      uint32_t acc = 0;
+      for (size_t i = 0; i < N; ++i) {
+        acc ^= values[i] >> shifts[i];
+      }
+      ankerl::nanobench::doNotOptimizeAway(acc);
+    });
+
+    bench.run("sar<"s + typeName + ">", [&] {
+      uint32_t acc = 0;
+      for (size_t i = 0; i < N; ++i) {
+        acc ^= sar(values[i], shifts[i]);
+      }
+      ankerl::nanobench::doNotOptimizeAway(acc);
+    });
+  };
+
+  auto salBench1 = createBench("Compare sal vs builtin << (uint32_t)");
+  runSalBench(salBench1, "uint32_t", u32, shl32);
+
+  auto salBench2 = createBench("Compare sal vs builtin << (uint64_t)");
+  runSalBench(salBench2, "uint64_t", u64, shl64);
+
+  auto sarBench1 = createBench("Compare sar vs builtin >> (uint32_t)");
+  runSarBench(sarBench1, "uint32_t", u32, shl32);
+
+  auto sarBench2 = createBench("Compare sar vs builtin >> (uint64_t)");
+  runSarBench(sarBench2, "uint64_t", u64, shl64);
 }