libcxx/benchmarks/libcxxabi/dynamic_cast.bench.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include <cstddef>
  10
  11 #include "benchmark/benchmark.h"
  12
  13 template <std::size_t Depth>
  14 struct Chain : Chain<Depth - 1> {};
  15
  16 template <>
  17 struct Chain<0> {
  18   virtual ~Chain() noexcept = default;
  19 };
  20
  21 template <std::size_t Index, std::size_t Depth>
  22 struct Dag : Dag<Index, Depth - 1>, Dag<Index + 1, Depth - 1> {};
  23
  24 template <std::size_t Index>
  25 struct Dag<Index, 0> {
  26   virtual ~Dag() noexcept = default;
  27 };
  28
  29 template <std::size_t Depth>
  30 struct VChain : virtual VChain<Depth - 1> {};
  31
  32 template <>
  33 struct VChain<0> {
  34   virtual ~VChain() noexcept = default;
  35 };
  36
  37 template <std::size_t Index, std::size_t Depth>
  38 struct VDag : virtual VDag<Index, Depth - 1>, virtual VDag<Index + 1, Depth - 1> {};
  39
  40 template <std::size_t Index>
  41 struct VDag<Index, 0> {
  42   virtual ~VDag() noexcept = default;
  43 };
  44
  45 template <typename Dyn, typename From, typename To = Dyn>
  46 static void DynCast(benchmark::State& state) {
  47   Dyn obj;
  48   From* from_ptr = &obj;
  49   for (auto _ : state) {
  50     To* to_ptr = dynamic_cast<To*>(from_ptr);
  51     benchmark::DoNotOptimize(to_ptr);
  52   }
  53 }
  54
  55 static void StaticCast(benchmark::State& state) {
  56   Chain<9> obj;
  57   Chain<0>* from_ptr = &obj;
  58   for (auto _ : state) {
  59     Chain<9>* to_ptr = static_cast<Chain<9>*>(from_ptr);
  60     benchmark::DoNotOptimize(to_ptr);
  61   }
  62 }
  63
  64 // Downcast along a chain from base to the most derived type
  65 BENCHMARK(DynCast<Chain<1>, Chain<0>>)->Name("Chain, 1 level");
  66 BENCHMARK(DynCast<Chain<2>, Chain<0>>)->Name("Chain, 2 levels");
  67 BENCHMARK(DynCast<Chain<3>, Chain<0>>)->Name("Chain, 3 levels");
  68 BENCHMARK(DynCast<Chain<4>, Chain<0>>)->Name("Chain, 4 levels");
  69 BENCHMARK(DynCast<Chain<5>, Chain<0>>)->Name("Chain, 5 levels");
  70 BENCHMARK(DynCast<Chain<6>, Chain<0>>)->Name("Chain, 6 levels");
  71 BENCHMARK(DynCast<Chain<7>, Chain<0>>)->Name("Chain, 7 levels");
  72 BENCHMARK(DynCast<Chain<8>, Chain<0>>)->Name("Chain, 8 levels");
  73 BENCHMARK(DynCast<Chain<9>, Chain<0>>)->Name("Chain, 9 levels");
  74
  75 // Downcast along a chain from base to the middle of the chain
  76 BENCHMARK(DynCast<Chain<2>, Chain<0>, Chain<1>>)->Name("Chain middle, 1 level");
  77 BENCHMARK(DynCast<Chain<4>, Chain<0>, Chain<2>>)->Name("Chain middle, 2 levels");
  78 BENCHMARK(DynCast<Chain<6>, Chain<0>, Chain<3>>)->Name("Chain middle, 3 levels");
  79 BENCHMARK(DynCast<Chain<8>, Chain<0>, Chain<4>>)->Name("Chain middle, 4 levels");
  80
  81 // Downcast along a chain that fails
  82 BENCHMARK(DynCast<Chain<1>, Chain<0>, Chain<9>>)->Name("Chain fail, 1 level");
  83 BENCHMARK(DynCast<Chain<2>, Chain<0>, Chain<9>>)->Name("Chain fail, 2 levels");
  84 BENCHMARK(DynCast<Chain<3>, Chain<0>, Chain<9>>)->Name("Chain fail, 3 levels");
  85 BENCHMARK(DynCast<Chain<4>, Chain<0>, Chain<9>>)->Name("Chain fail, 4 levels");
  86 BENCHMARK(DynCast<Chain<5>, Chain<0>, Chain<9>>)->Name("Chain fail, 5 levels");
  87 BENCHMARK(DynCast<Chain<6>, Chain<0>, Chain<9>>)->Name("Chain fail, 6 levels");
  88 BENCHMARK(DynCast<Chain<7>, Chain<0>, Chain<9>>)->Name("Chain fail, 7 levels");
  89 BENCHMARK(DynCast<Chain<8>, Chain<0>, Chain<9>>)->Name("Chain fail, 8 levels");
  90
  91 // Downcast along a virtual inheritance chain from base to the most derived type
  92 BENCHMARK(DynCast<VChain<1>, VChain<0>>)->Name("VChain, 1 level");
  93 BENCHMARK(DynCast<VChain<2>, VChain<0>>)->Name("VChain, 2 levels");
  94 BENCHMARK(DynCast<VChain<3>, VChain<0>>)->Name("VChain, 3 levels");
  95 BENCHMARK(DynCast<VChain<4>, VChain<0>>)->Name("VChain, 4 levels");
  96 BENCHMARK(DynCast<VChain<5>, VChain<0>>)->Name("VChain, 5 levels");
  97
  98 // Downcast along a virtual inheritance chain from base to the middle of the chain
  99 BENCHMARK(DynCast<VChain<2>, VChain<0>, VChain<1>>)->Name("VChain middle, 1 level");
 100 BENCHMARK(DynCast<VChain<4>, VChain<0>, VChain<2>>)->Name("VChain middle, 2 levels");
 101 BENCHMARK(DynCast<VChain<6>, VChain<0>, VChain<3>>)->Name("VChain middle, 3 levels");
 102 BENCHMARK(DynCast<VChain<8>, VChain<0>, VChain<4>>)->Name("VChain middle, 4 levels");
 103
 104 // Downcast along a virtual chain that fails
 105 BENCHMARK(DynCast<VChain<1>, VChain<0>, VChain<8>>)->Name("VChain fail, 1 level");
 106 BENCHMARK(DynCast<VChain<2>, VChain<0>, VChain<8>>)->Name("VChain fail, 2 levels");
 107 BENCHMARK(DynCast<VChain<3>, VChain<0>, VChain<8>>)->Name("VChain fail, 3 levels");
 108 BENCHMARK(DynCast<VChain<4>, VChain<0>, VChain<8>>)->Name("VChain fail, 4 levels");
 109 BENCHMARK(DynCast<VChain<5>, VChain<0>, VChain<8>>)->Name("VChain fail, 5 levels");
 110
 111 // Downcast along a DAG from base to the most derived type
 112 BENCHMARK(DynCast<Dag<0, 3>, Dag<3, 0>>)->Name("DAG rightmost, 3 levels");
 113 BENCHMARK(DynCast<Dag<0, 4>, Dag<4, 0>>)->Name("DAG rightmost, 4 levels");
 114 BENCHMARK(DynCast<Dag<0, 5>, Dag<5, 0>>)->Name("DAG rightmost, 5 levels");
 115 BENCHMARK(DynCast<Dag<0, 3>, Dag<0, 0>>)->Name("DAG leftmost, 3 levels");
 116 BENCHMARK(DynCast<Dag<0, 4>, Dag<0, 0>>)->Name("DAG leftmost, 4 levels");
 117 BENCHMARK(DynCast<Dag<0, 5>, Dag<0, 0>>)->Name("DAG leftmost, 5 levels");
 118
 119 // Downcast along a DAG from base to the middle of the DAG
 120 BENCHMARK(DynCast<Dag<0, 4>, Dag<4, 0>, Dag<3, 1>>)->Name("DAG rightmost middle, 1 level");
 121 BENCHMARK(DynCast<Dag<0, 4>, Dag<4, 0>, Dag<2, 2>>)->Name("DAG rightmost middle, 2 levels");
 122 BENCHMARK(DynCast<Dag<0, 4>, Dag<4, 0>, Dag<1, 3>>)->Name("DAG rightmost middle, 3 levels");
 123 BENCHMARK(DynCast<Dag<0, 4>, Dag<0, 0>, Dag<0, 1>>)->Name("DAG leftmost middle, 1 level");
 124 BENCHMARK(DynCast<Dag<0, 4>, Dag<0, 0>, Dag<0, 2>>)->Name("DAG leftmost middle, 2 levels");
 125 BENCHMARK(DynCast<Dag<0, 4>, Dag<0, 0>, Dag<0, 3>>)->Name("DAG leftmost middle, 3 levels");
 126
 127 // Sidecast along a DAG
 128 BENCHMARK(DynCast<Dag<0, 3>, Dag<3, 0>, Dag<0, 0>>)->Name("DAG sidecast, 3 levels");
 129 BENCHMARK(DynCast<Dag<0, 3>, Dag<2, 1>, Dag<0, 1>>)->Name("DAG sidecast, 2 levels");
 130 BENCHMARK(DynCast<Dag<0, 3>, Dag<1, 2>, Dag<0, 2>>)->Name("DAG sidecast, 1 level");
 131
 132 // Sidecast along a DAG that fails
 133 BENCHMARK(DynCast<Dag<0, 3>, Dag<3, 0>, Dag<0, 4>>)->Name("DAG sidecast fail, 3 levels");
 134 BENCHMARK(DynCast<Dag<0, 3>, Dag<2, 1>, Dag<0, 4>>)->Name("DAG sidecast fail, 2 levels");
 135 BENCHMARK(DynCast<Dag<0, 3>, Dag<1, 2>, Dag<0, 4>>)->Name("DAG sidecast fail, 1 level");
 136
 137 // Downcast along a virtual inheritance DAG from base to the most derived type
 138 BENCHMARK(DynCast<VDag<0, 3>, VDag<3, 0>>)->Name("VDAG rightmost, 3 levels");
 139 BENCHMARK(DynCast<VDag<0, 4>, VDag<4, 0>>)->Name("VDAG rightmost, 4 levels");
 140 BENCHMARK(DynCast<VDag<0, 5>, VDag<5, 0>>)->Name("VDAG rightmost, 5 levels");
 141 BENCHMARK(DynCast<VDag<0, 3>, VDag<0, 0>>)->Name("VDAG leftmost, 3 levels");
 142 BENCHMARK(DynCast<VDag<0, 4>, VDag<0, 0>>)->Name("VDAG leftmost, 4 levels");
 143 BENCHMARK(DynCast<VDag<0, 5>, VDag<0, 0>>)->Name("VDAG leftmost, 5 levels");
 144
 145 // Downcast along a virtual inheritance DAG from base to the middle of the DAG
 146 BENCHMARK(DynCast<VDag<0, 3>, VDag<3, 0>, VDag<2, 1>>)->Name("VDAG rightmost middle, 1 level");
 147 BENCHMARK(DynCast<VDag<0, 4>, VDag<4, 0>, VDag<2, 2>>)->Name("VDAG rightmost middle, 2 levels");
 148 BENCHMARK(DynCast<VDag<0, 5>, VDag<5, 0>, VDag<2, 3>>)->Name("VDAG rightmost middle, 3 levels");
 149 BENCHMARK(DynCast<VDag<0, 3>, VDag<0, 0>, VDag<0, 1>>)->Name("VDAG leftmost middle, 1 level");
 150 BENCHMARK(DynCast<VDag<0, 4>, VDag<0, 0>, VDag<0, 2>>)->Name("VDAG leftmost middle, 2 levels");
 151 BENCHMARK(DynCast<VDag<0, 5>, VDag<0, 0>, VDag<0, 3>>)->Name("VDAG leftmost middle, 3 levels");
 152
 153 // Sidecast along a virtual inheritance DAG
 154 BENCHMARK(DynCast<VDag<0, 3>, VDag<3, 0>, VDag<0, 0>>)->Name("VDAG sidecast, 3 levels");
 155 BENCHMARK(DynCast<VDag<0, 3>, VDag<2, 1>, VDag<0, 1>>)->Name("VDAG sidecast, 2 levels");
 156 BENCHMARK(DynCast<VDag<0, 3>, VDag<1, 2>, VDag<0, 2>>)->Name("VDAG sidecast, 1 level");
 157
 158 // Sidecast along a virtual inheritance DAG that fails
 159 BENCHMARK(DynCast<VDag<0, 3>, VDag<3, 0>, VDag<0, 4>>)->Name("VDAG sidecast fail, 3 levels");
 160 BENCHMARK(DynCast<VDag<0, 3>, VDag<2, 1>, VDag<0, 4>>)->Name("VDAG sidecast fail, 2 levels");
 161 BENCHMARK(DynCast<VDag<0, 3>, VDag<1, 2>, VDag<0, 4>>)->Name("VDAG sidecast fail, 1 level");
 162
 163 // Cast to complete object pointer
 164 BENCHMARK(DynCast<Chain<8>, Chain<0>, void>)->Name("Chain to complete");
 165 BENCHMARK(DynCast<VChain<5>, VChain<0>, void>)->Name("VChain to complete");
 166 BENCHMARK(DynCast<Dag<0, 3>, Dag<3, 0>, void>)->Name("DAG to complete");
 167 BENCHMARK(DynCast<VDag<0, 3>, VDag<3, 0>, void>)->Name("VDAG to complete");
 168
 169 // Static cast as the baseline.
 170 BENCHMARK(StaticCast)->Name("Static");
 171
 172 BENCHMARK_MAIN();