llvm-project

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#include "benchmark/benchmark.h"
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#include "test_macros.h"
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#include <mutex>
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#include <sstream>
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TEST_NOINLINE double istream_numbers();
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double istream_numbers(std::locale* loc) {
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  const char* a[] = {"-6  69 -71  2.4882e-02 -100 101 -2.00005 5000000 -50000000",
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                     "-25 71   7 -9.3262e+01 -100 101 -2.00005 5000000 -50000000",
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                     "-14 53  46 -6.7026e-02 -100 101 -2.00005 5000000 -50000000"};
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  int a1, a2, a3, a4, a5, a6, a7;
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  double f1 = 0.0, f2 = 0.0, q = 0.0;
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  for (int i = 0; i < 3; i++) {
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    std::istringstream s(a[i]);
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    if (loc)
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      s.imbue(*loc);
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    s >> a1 >> a2 >> a3 >> f1 >> a4 >> a5 >> f2 >> a6 >> a7;
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    q += (a1 + a2 + a3 + a4 + a5 + a6 + a7 + f1 + f2) / 1000000;
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  }
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  return q;
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}
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struct LocaleSelector {
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  std::locale* imbue;
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  std::locale old;
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  static std::mutex mutex;
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  LocaleSelector(benchmark::State& state) {
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    std::lock_guard guard(mutex);
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    switch (state.range(0)) {
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    case 0: {
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      old   = std::locale::global(std::locale::classic());
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      imbue = nullptr;
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      break;
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    }
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    case 1: {
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      old = std::locale::global(std::locale::classic());
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      thread_local std::locale loc("en_US.UTF-8");
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      imbue = &loc;
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      break;
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    }
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    case 2: {
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      old = std::locale::global(std::locale::classic());
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      static std::locale loc("en_US.UTF-8");
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      imbue = &loc;
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      break;
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    }
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    case 3: {
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      old   = std::locale::global(std::locale("en_US.UTF-8"));
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      imbue = nullptr;
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      break;
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    }
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    }
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  }
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  ~LocaleSelector() {
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    std::lock_guard guard(mutex);
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    std::locale::global(old);
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  }
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};
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std::mutex LocaleSelector::mutex;
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static void BM_Istream_numbers(benchmark::State& state) {
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  LocaleSelector sel(state);
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  double i = 0;
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  while (state.KeepRunning())
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    benchmark::DoNotOptimize(i += istream_numbers(sel.imbue));
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}
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BENCHMARK(BM_Istream_numbers)->DenseRange(0, 3)->UseRealTime()->Threads(1)->ThreadPerCpu();
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static void BM_Ostream_number(benchmark::State& state) {
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  LocaleSelector sel(state);
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  while (state.KeepRunning()) {
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    std::ostringstream ss;
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    if (sel.imbue)
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      ss.imbue(*sel.imbue);
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    ss << 0;
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    benchmark::DoNotOptimize(ss.str().c_str());
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  }
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}
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BENCHMARK(BM_Ostream_number)->DenseRange(0, 3)->UseRealTime()->Threads(1)->ThreadPerCpu();
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BENCHMARK_MAIN();
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