1 | #include <time.h>
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2 | #include <cstring>
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3 | #include <memory>
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4 | #include <iomanip>
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5 | #include <iostream>
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6 | #include <algorithm>
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7 | #include <boost/config.hpp>
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8 | #include <boost/uuid/uuid.hpp>
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9 | #include <boost/uuid/uuid_generators.hpp>
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10 | #if defined(BOOST_WINDOWS)
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11 | #define WIN32_LEAN_AND_MEAN
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12 | #include <windows.h>
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13 | #endif
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14 | #if defined(_MSC_VER)
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15 | // MSVC does not always have immintrin.h (at least, not up to MSVC 10), and we cannot detect the target higher than SSE2 anyway, so just include this header
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16 | #include <emmintrin.h>
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17 | #else
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18 | #include <immintrin.h>
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19 | #endif
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20 |
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21 | using boost::uuids::uuid;
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22 |
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23 | bool stock_equal(uuid const& left, uuid const& right)
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24 | {
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25 | return std::equal(left.begin(), left.end(), right.begin());
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26 | }
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27 |
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28 | bool mem_equal(uuid const& left, uuid const& right)
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29 | {
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30 | return std::memcmp(left.data, right.data, 16) == 0;
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31 | }
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32 |
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33 | bool simd_equal(uuid const& left, uuid const& right)
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34 | {
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35 | #if defined(__SSE3__)
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36 | __m128i mm_left = _mm_lddqu_si128(reinterpret_cast< const __m128i* >(left.data));
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37 | __m128i mm_right = _mm_lddqu_si128(reinterpret_cast< const __m128i* >(right.data));
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38 | #else
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39 | __m128i mm_left = _mm_loadu_si128(reinterpret_cast< const __m128i* >(left.data));
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40 | __m128i mm_right = _mm_loadu_si128(reinterpret_cast< const __m128i* >(right.data));
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41 | #endif
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42 | __m128i mm_cmp = _mm_cmpeq_epi32(mm_left, mm_right);
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43 | #if defined(__SSE4_1__)
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44 | return _mm_test_all_ones(mm_cmp);
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45 | #else
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46 | return _mm_movemask_epi8(mm_cmp) == 0xFFFF;
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47 | #endif
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48 | }
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49 |
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50 |
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51 | bool stock_less(uuid const& left, uuid const& right)
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52 | {
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53 | return std::lexicographical_compare(left.begin(), left.end(), right.begin(), right.end());
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54 | }
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55 |
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56 | bool mem_less(uuid const& left, uuid const& right)
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57 | {
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58 | return std::memcmp(left.data, right.data, 16) < 0;
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59 | }
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60 |
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61 | bool simd_less(uuid const& left, uuid const& right)
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62 | {
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63 | #if defined(__SSE3__)
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64 | __m128i mm_left = _mm_lddqu_si128(reinterpret_cast< const __m128i* >(left.data));
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65 | __m128i mm_right = _mm_lddqu_si128(reinterpret_cast< const __m128i* >(right.data));
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66 | #else
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67 | __m128i mm_left = _mm_loadu_si128(reinterpret_cast< const __m128i* >(left.data));
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68 | __m128i mm_right = _mm_loadu_si128(reinterpret_cast< const __m128i* >(right.data));
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69 | #endif
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70 |
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71 | // To emulate lexicographical_compare behavior we have to perform two comparisons - the forward and reverse one.
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72 | // Then we know which bytes are equivalent and which ones are different, and for those different the comparison results
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73 | // will be opposite. Then we'll be able to find the first differing comparison result (for both forward and reverse ways),
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74 | // and depending on which way it is for, this will be the result of the operation. There are a few notes to consider:
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75 | //
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76 | // 1. Due to little endian byte order the first bytes go into the lower part of the xmm registers,
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77 | // so the comparison results in the least significant bits will actually be the most signigicant for the final operation result.
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78 | // This means we have to determine which of the comparison results have the least significant bit on, and this is achieved with
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79 | // the "(x - 1) ^ x" trick.
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80 | // 2. Because there is only signed comparison in SSE/AVX, we have to operate on 16 bit integers. We zero-extend bytes to 16 bit words
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81 | // before comparison and then pack the comparison results back to 8 bits. For AVX2 we can still do the comparison in one instruction though.
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82 | // 3. pcmpgtw compares for "greater" relation, so we swap the arguments to get what we need.
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83 | const __m128i mm_0 = _mm_setzero_si128();
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84 | __m128i mm_left_lo = _mm_unpacklo_epi8(mm_left, mm_0), mm_right_lo = _mm_unpacklo_epi8(mm_right, mm_0);
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85 | __m128i mm_left_hi = _mm_unpackhi_epi8(mm_left, mm_0), mm_right_hi = _mm_unpackhi_epi8(mm_right, mm_0);
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86 |
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87 | __m128i mm_cmp_lo = _mm_cmpgt_epi16(mm_right_lo, mm_left_lo), mm_cmp_hi = _mm_cmpgt_epi16(mm_right_hi, mm_left_hi);
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88 | __m128i mm_rcmp_lo = _mm_cmpgt_epi16(mm_left_lo, mm_right_lo), mm_rcmp_hi = _mm_cmpgt_epi16(mm_left_hi, mm_right_hi);
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89 | __m128i mm_cmp = _mm_packs_epi16(mm_cmp_lo, mm_cmp_hi);
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90 | __m128i mm_rcmp = _mm_packs_epi16(mm_rcmp_lo, mm_rcmp_hi);
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91 |
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92 | boost::uint32_t cmp = _mm_movemask_epi8(mm_cmp), rcmp = _mm_movemask_epi8(mm_rcmp);
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93 | cmp = (cmp - 1u) ^ cmp;
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94 | rcmp = (rcmp - 1u) ^ rcmp;
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95 |
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96 | return static_cast< boost::uint16_t >(cmp) < static_cast< boost::uint16_t >(rcmp);
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97 | }
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98 |
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99 | typedef bool equal_t(uuid const& left, uuid const& right);
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100 |
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101 | const unsigned int iterations = 100000000u;
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102 |
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103 | void test_performance(uuid const& left, uuid const& right, const char* name, equal_t* eq)
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104 | {
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105 | #if !defined(BOOST_WINDOWS)
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106 | struct timespec start = {}, end = {};
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107 | clock_gettime(CLOCK_REALTIME, &start);
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108 | #else
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109 | LARGE_INTEGER start = {}, end = {};
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110 | QueryPerformanceCounter(&start);
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111 | #endif
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112 |
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113 | for (volatile unsigned int i = 0; i < iterations; ++i)
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114 | {
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115 | eq(left, right);
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116 | }
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117 |
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118 | #if !defined(BOOST_WINDOWS)
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119 | clock_gettime(CLOCK_REALTIME, &end);
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120 |
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121 | boost::uint64_t duration = (end.tv_sec - start.tv_sec) * 1000000000ull + (end.tv_nsec - start.tv_nsec);
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122 | #else
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123 | QueryPerformanceCounter(&end);
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124 | LARGE_INTEGER freq = {};
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125 | QueryPerformanceFrequency(&freq);
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126 |
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127 | boost::uint64_t duration = (end.QuadPart - start.QuadPart) * 1000000000ull / freq.QuadPart;
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128 | #endif
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129 |
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130 | std::cout << name << " duration: " << duration << " ns" << std::endl;
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131 | }
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132 |
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133 | void run_tests(uuid const& left, uuid const& right)
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134 | {
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135 | test_performance(left, right, "stock_equal", &stock_equal);
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136 | test_performance(left, right, "mem_equal", &mem_equal);
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137 | test_performance(left, right, "simd_equal", &simd_equal);
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138 |
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139 | test_performance(left, right, "stock_less", &stock_less);
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140 | test_performance(left, right, "mem_less", &mem_less);
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141 | test_performance(left, right, "simd_less", &simd_less);
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142 | }
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143 |
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144 | int main(int, char*[])
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145 | {
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146 | boost::uuids::random_generator gen;
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147 |
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148 | {
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149 | std::cout << "Values placed on stack:" << std::endl;
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150 | uuid left = gen();
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151 | uuid right = gen();
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152 | run_tests(left, right);
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153 | }
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154 | {
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155 | std::cout << "\nValues placed on heap:" << std::endl;
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156 | std::auto_ptr< uuid > pleft(new uuid(gen()));
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157 | std::auto_ptr< uuid > pright(new uuid(gen()));
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158 | run_tests(*pleft, *pright);
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159 | }
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160 |
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161 | return 0;
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162 | }
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163 |
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