gistfile1.txt

C:\Users\bion\Desktop>type bench.cpp
#include "benchmark/benchmark.h"
#pragma comment(lib, "benchmark")
#pragma comment(lib, "shlwapi")

#include <stddef.h>
#include <algorithm>
#include <random>
#include <string>
#include <string_view>
#include <vector>

template<class Parameter>
__declspec(noinline)
size_t even_char_indexes(Parameter target) {
    // get all the offsets to chars with even values in `target`
    size_t result = 0;
    for (char c : target) {
        if ((c & 1) == 0) {
            ++result;
        }
    }

    return result;
}

template<class Parameter, size_t Count>
void benchmark_even_char_indexes(benchmark::State& state) {
    // fill a string of chars to test
    std::mt19937 gen(1729);
    char testData[Count + 1]{};
    std::generate(testData, testData + Count, [&gen]() {
        // &2 prevents nulls
        return static_cast<char>(static_cast<unsigned char>(gen() | 2));
        });

    for (auto _ : state) {
        even_char_indexes<Parameter>(testData);
    }
}

BENCHMARK_TEMPLATE2(benchmark_even_char_indexes, const std::string_view, 8);
BENCHMARK_TEMPLATE2(benchmark_even_char_indexes, const std::string_view, 16);
BENCHMARK_TEMPLATE2(benchmark_even_char_indexes, const std::string_view, 64);
BENCHMARK_TEMPLATE2(benchmark_even_char_indexes, const std::string_view, 256);
BENCHMARK_TEMPLATE2(benchmark_even_char_indexes, const std::string_view, 1024);
BENCHMARK_TEMPLATE2(benchmark_even_char_indexes, const std::string_view, 16768);
BENCHMARK_TEMPLATE2(benchmark_even_char_indexes, const std::string&, 8);
BENCHMARK_TEMPLATE2(benchmark_even_char_indexes, const std::string&, 16);
BENCHMARK_TEMPLATE2(benchmark_even_char_indexes, const std::string&, 64);
BENCHMARK_TEMPLATE2(benchmark_even_char_indexes, const std::string&, 256);
BENCHMARK_TEMPLATE2(benchmark_even_char_indexes, const std::string&, 1024);
BENCHMARK_TEMPLATE2(benchmark_even_char_indexes, const std::string&, 16768);

BENCHMARK_MAIN();

C:\Users\bion\Desktop>cl /nologo /EHsc /wd4141 /W4 /WX /O2 /std:c++17 /MD /IC:\Dev\vcpkg\installed\x86-windows\include .\bench.cpp /link /LIBPATH:C:\Dev\vcpkg\installed\x86-windows\lib
bench.cpp

C:\Users\bion\Desktop>.\bench.exe
Run on (32 X 2592 MHz CPU s)
12/12/17 18:30:48
-------------------------------------------------------------------------------------------------
Benchmark                                                          Time           CPU Iterations
-------------------------------------------------------------------------------------------------
benchmark_even_char_indexes<const std::string_view,8>              8 ns          8 ns   89600000
benchmark_even_char_indexes<const std::string_view,16>            14 ns         13 ns   49777778
benchmark_even_char_indexes<const std::string_view,64>            49 ns         49 ns   11200000
benchmark_even_char_indexes<const std::string_view,256>          209 ns        210 ns    3200000
benchmark_even_char_indexes<const std::string_view,1024>         781 ns        781 ns    1120000
benchmark_even_char_indexes<const std::string_view,16768>      12537 ns      12556 ns      56000
benchmark_even_char_indexes<const std::string&,8>                  7 ns          7 ns  112000000
benchmark_even_char_indexes<const std::string&,16>                55 ns         56 ns   10000000
benchmark_even_char_indexes<const std::string&,64>                70 ns         70 ns    8960000
benchmark_even_char_indexes<const std::string&,256>              141 ns        141 ns    4977778
benchmark_even_char_indexes<const std::string&,1024>             370 ns        369 ns    1947826
benchmark_even_char_indexes<const std::string&,16768>           5291 ns       5162 ns     112000

C:\Users\bion\Desktop>