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<div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span> <span class="comment">/**</span></div>
<div class="line"><a name="l00002"></a><span class="lineno"> 2</span> <span class="comment"> * Copyright (c) 2015-present, Facebook, Inc.</span></div>
<div class="line"><a name="l00003"></a><span class="lineno"> 3</span> <span class="comment"> * All rights reserved.</span></div>
<div class="line"><a name="l00004"></a><span class="lineno"> 4</span> <span class="comment"> *</span></div>
<div class="line"><a name="l00005"></a><span class="lineno"> 5</span> <span class="comment"> * This source code is licensed under the BSD+Patents license found in the</span></div>
<div class="line"><a name="l00006"></a><span class="lineno"> 6</span> <span class="comment"> * LICENSE file in the root directory of this source tree.</span></div>
<div class="line"><a name="l00007"></a><span class="lineno"> 7</span> <span class="comment"> */</span></div>
<div class="line"><a name="l00008"></a><span class="lineno"> 8</span> </div>
<div class="line"><a name="l00009"></a><span class="lineno"> 9</span> <span class="comment">// Copyright 2004-present Facebook. All Rights Reserved.</span></div>
<div class="line"><a name="l00010"></a><span class="lineno"> 10</span> <span class="preprocessor">#pragma once</span></div>
<div class="line"><a name="l00011"></a><span class="lineno"> 11</span> <span class="preprocessor"></span></div>
<div class="line"><a name="l00012"></a><span class="lineno"> 12</span> <span class="preprocessor">#include "DeviceDefs.cuh"</span></div>
<div class="line"><a name="l00013"></a><span class="lineno"> 13</span> <span class="preprocessor">#include "MergeNetworkUtils.cuh"</span></div>
<div class="line"><a name="l00014"></a><span class="lineno"> 14</span> <span class="preprocessor">#include "PtxUtils.cuh"</span></div>
<div class="line"><a name="l00015"></a><span class="lineno"> 15</span> <span class="preprocessor">#include "StaticUtils.h"</span></div>
<div class="line"><a name="l00016"></a><span class="lineno"> 16</span> <span class="preprocessor">#include "WarpShuffles.cuh"</span></div>
<div class="line"><a name="l00017"></a><span class="lineno"> 17</span> </div>
<div class="line"><a name="l00018"></a><span class="lineno"> 18</span> <span class="keyword">namespace </span>faiss { <span class="keyword">namespace </span>gpu {</div>
<div class="line"><a name="l00019"></a><span class="lineno"> 19</span> </div>
<div class="line"><a name="l00020"></a><span class="lineno"> 20</span> <span class="comment">//</span></div>
<div class="line"><a name="l00021"></a><span class="lineno"> 21</span> <span class="comment">// This file contains functions to:</span></div>
<div class="line"><a name="l00022"></a><span class="lineno"> 22</span> <span class="comment">//</span></div>
<div class="line"><a name="l00023"></a><span class="lineno"> 23</span> <span class="comment">// -perform bitonic merges on pairs of sorted lists, held in</span></div>
<div class="line"><a name="l00024"></a><span class="lineno"> 24</span> <span class="comment">// registers. Each list contains N * kWarpSize (multiple of 32)</span></div>
<div class="line"><a name="l00025"></a><span class="lineno"> 25</span> <span class="comment">// elements for some N.</span></div>
<div class="line"><a name="l00026"></a><span class="lineno"> 26</span> <span class="comment">// The bitonic merge is implemented for arbitrary sizes;</span></div>
<div class="line"><a name="l00027"></a><span class="lineno"> 27</span> <span class="comment">// sorted list A of size N1 * kWarpSize registers</span></div>
<div class="line"><a name="l00028"></a><span class="lineno"> 28</span> <span class="comment">// sorted list B of size N2 * kWarpSize registers =></span></div>
<div class="line"><a name="l00029"></a><span class="lineno"> 29</span> <span class="comment">// sorted list C if size (N1 + N2) * kWarpSize registers. N1 and N2</span></div>
<div class="line"><a name="l00030"></a><span class="lineno"> 30</span> <span class="comment">// are >= 1 and don't have to be powers of 2.</span></div>
<div class="line"><a name="l00031"></a><span class="lineno"> 31</span> <span class="comment">//</span></div>
<div class="line"><a name="l00032"></a><span class="lineno"> 32</span> <span class="comment">// -perform bitonic sorts on a set of N * kWarpSize key/value pairs</span></div>
<div class="line"><a name="l00033"></a><span class="lineno"> 33</span> <span class="comment">// held in registers, by using the above bitonic merge as a</span></div>
<div class="line"><a name="l00034"></a><span class="lineno"> 34</span> <span class="comment">// primitive.</span></div>
<div class="line"><a name="l00035"></a><span class="lineno"> 35</span> <span class="comment">// N can be an arbitrary N >= 1; i.e., the bitonic sort here supports</span></div>
<div class="line"><a name="l00036"></a><span class="lineno"> 36</span> <span class="comment">// odd sizes and doesn't require the input to be a power of 2.</span></div>
<div class="line"><a name="l00037"></a><span class="lineno"> 37</span> <span class="comment">//</span></div>
<div class="line"><a name="l00038"></a><span class="lineno"> 38</span> <span class="comment">// The sort or merge network is completely statically instantiated via</span></div>
<div class="line"><a name="l00039"></a><span class="lineno"> 39</span> <span class="comment">// template specialization / expansion and constexpr, and it uses warp</span></div>
<div class="line"><a name="l00040"></a><span class="lineno"> 40</span> <span class="comment">// shuffles to exchange values between warp lanes.</span></div>
<div class="line"><a name="l00041"></a><span class="lineno"> 41</span> <span class="comment">//</span></div>
<div class="line"><a name="l00042"></a><span class="lineno"> 42</span> <span class="comment">// A note about comparsions:</span></div>
<div class="line"><a name="l00043"></a><span class="lineno"> 43</span> <span class="comment">//</span></div>
<div class="line"><a name="l00044"></a><span class="lineno"> 44</span> <span class="comment">// For a sorting network of keys only, we only need one</span></div>
<div class="line"><a name="l00045"></a><span class="lineno"> 45</span> <span class="comment">// comparison (a < b). However, what we really need to know is</span></div>
<div class="line"><a name="l00046"></a><span class="lineno"> 46</span> <span class="comment">// if one lane chooses to exchange a value, then the</span></div>
<div class="line"><a name="l00047"></a><span class="lineno"> 47</span> <span class="comment">// corresponding lane should also do the exchange.</span></div>
<div class="line"><a name="l00048"></a><span class="lineno"> 48</span> <span class="comment">// Thus, if one just uses the negation !(x < y) in the higher</span></div>
<div class="line"><a name="l00049"></a><span class="lineno"> 49</span> <span class="comment">// lane, this will also include the case where (x == y). Thus, one</span></div>
<div class="line"><a name="l00050"></a><span class="lineno"> 50</span> <span class="comment">// lane in fact performs an exchange and the other doesn't, but</span></div>
<div class="line"><a name="l00051"></a><span class="lineno"> 51</span> <span class="comment">// because the only value being exchanged is equivalent, nothing has</span></div>
<div class="line"><a name="l00052"></a><span class="lineno"> 52</span> <span class="comment">// changed.</span></div>
<div class="line"><a name="l00053"></a><span class="lineno"> 53</span> <span class="comment">// So, you can get away with just one comparison and its negation.</span></div>
<div class="line"><a name="l00054"></a><span class="lineno"> 54</span> <span class="comment">//</span></div>
<div class="line"><a name="l00055"></a><span class="lineno"> 55</span> <span class="comment">// If we're sorting keys and values, where equivalent keys can</span></div>
<div class="line"><a name="l00056"></a><span class="lineno"> 56</span> <span class="comment">// exist, then this is a problem, since we want to treat (x, v1)</span></div>
<div class="line"><a name="l00057"></a><span class="lineno"> 57</span> <span class="comment">// as not equivalent to (x, v2).</span></div>
<div class="line"><a name="l00058"></a><span class="lineno"> 58</span> <span class="comment">//</span></div>
<div class="line"><a name="l00059"></a><span class="lineno"> 59</span> <span class="comment">// To remedy this, you can either compare with a lexicographic</span></div>
<div class="line"><a name="l00060"></a><span class="lineno"> 60</span> <span class="comment">// ordering (a.k < b.k || (a.k == b.k && a.v < b.v)), which since</span></div>
<div class="line"><a name="l00061"></a><span class="lineno"> 61</span> <span class="comment">// we're predicating all of the choices results in 3 comparisons</span></div>
<div class="line"><a name="l00062"></a><span class="lineno"> 62</span> <span class="comment">// being executed, or we can invert the selection so that there is no</span></div>
<div class="line"><a name="l00063"></a><span class="lineno"> 63</span> <span class="comment">// middle choice of equality; the other lane will likewise</span></div>
<div class="line"><a name="l00064"></a><span class="lineno"> 64</span> <span class="comment">// check that (b.k > a.k) (the higher lane has the values</span></div>
<div class="line"><a name="l00065"></a><span class="lineno"> 65</span> <span class="comment">// swapped). Then, the first lane swaps if and only if the</span></div>
<div class="line"><a name="l00066"></a><span class="lineno"> 66</span> <span class="comment">// second lane swaps; if both lanes have equivalent keys, no</span></div>
<div class="line"><a name="l00067"></a><span class="lineno"> 67</span> <span class="comment">// swap will be performed. This results in only two comparisons</span></div>
<div class="line"><a name="l00068"></a><span class="lineno"> 68</span> <span class="comment">// being executed.</span></div>
<div class="line"><a name="l00069"></a><span class="lineno"> 69</span> <span class="comment">//</span></div>
<div class="line"><a name="l00070"></a><span class="lineno"> 70</span> <span class="comment">// If you don't consider values as well, then this does not produce a</span></div>
<div class="line"><a name="l00071"></a><span class="lineno"> 71</span> <span class="comment">// consistent ordering among (k, v) pairs with equivalent keys but</span></div>
<div class="line"><a name="l00072"></a><span class="lineno"> 72</span> <span class="comment">// different values; for us, we don't really care about ordering or</span></div>
<div class="line"><a name="l00073"></a><span class="lineno"> 73</span> <span class="comment">// stability here.</span></div>
<div class="line"><a name="l00074"></a><span class="lineno"> 74</span> <span class="comment">//</span></div>
<div class="line"><a name="l00075"></a><span class="lineno"> 75</span> <span class="comment">// I have tried both re-arranging the order in the higher lane to get</span></div>
<div class="line"><a name="l00076"></a><span class="lineno"> 76</span> <span class="comment">// away with one comparison or adding the value to the check; both</span></div>
<div class="line"><a name="l00077"></a><span class="lineno"> 77</span> <span class="comment">// result in greater register consumption or lower speed than just</span></div>
<div class="line"><a name="l00078"></a><span class="lineno"> 78</span> <span class="comment">// perfoming both < and > comparisons with the variables, so I just</span></div>
<div class="line"><a name="l00079"></a><span class="lineno"> 79</span> <span class="comment">// stick with this.</span></div>
<div class="line"><a name="l00080"></a><span class="lineno"> 80</span> </div>
<div class="line"><a name="l00081"></a><span class="lineno"> 81</span> <span class="comment">// This function merges kWarpSize / 2L lists in parallel using warp</span></div>
<div class="line"><a name="l00082"></a><span class="lineno"> 82</span> <span class="comment">// shuffles.</span></div>
<div class="line"><a name="l00083"></a><span class="lineno"> 83</span> <span class="comment">// It works on at most size-16 lists, as we need 32 threads for this</span></div>
<div class="line"><a name="l00084"></a><span class="lineno"> 84</span> <span class="comment">// shuffle merge.</span></div>
<div class="line"><a name="l00085"></a><span class="lineno"> 85</span> <span class="comment">//</span></div>
<div class="line"><a name="l00086"></a><span class="lineno"> 86</span> <span class="comment">// If IsBitonic is false, the first stage is reversed, so we don't</span></div>
<div class="line"><a name="l00087"></a><span class="lineno"> 87</span> <span class="comment">// need to sort directionally. It's still technically a bitonic sort.</span></div>
<div class="line"><a name="l00088"></a><span class="lineno"> 88</span> <span class="keyword">template</span> <<span class="keyword">typename</span> K, <span class="keyword">typename</span> V, <span class="keywordtype">int</span> L,</div>
<div class="line"><a name="l00089"></a><span class="lineno"> 89</span>  <span class="keywordtype">bool</span> Dir, <span class="keyword">typename</span> Comp, <span class="keywordtype">bool</span> IsBitonic></div>
<div class="line"><a name="l00090"></a><span class="lineno"> 90</span> <span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> warpBitonicMergeLE16(K& k, V& v) {</div>
<div class="line"><a name="l00091"></a><span class="lineno"> 91</span>  static_assert(utils::isPowerOf2(L), <span class="stringliteral">"L must be a power-of-2"</span>);</div>
<div class="line"><a name="l00092"></a><span class="lineno"> 92</span>  static_assert(L <= kWarpSize / 2, <span class="stringliteral">"merge list size must be <= 16"</span>);</div>
<div class="line"><a name="l00093"></a><span class="lineno"> 93</span> </div>
<div class="line"><a name="l00094"></a><span class="lineno"> 94</span>  <span class="keywordtype">int</span> laneId = getLaneId();</div>
<div class="line"><a name="l00095"></a><span class="lineno"> 95</span> </div>
<div class="line"><a name="l00096"></a><span class="lineno"> 96</span>  <span class="keywordflow">if</span> (!IsBitonic) {</div>
<div class="line"><a name="l00097"></a><span class="lineno"> 97</span>  <span class="comment">// Reverse the first comparison stage.</span></div>
<div class="line"><a name="l00098"></a><span class="lineno"> 98</span>  <span class="comment">// For example, merging a list of size 8 has the exchanges:</span></div>
<div class="line"><a name="l00099"></a><span class="lineno"> 99</span>  <span class="comment">// 0 <-> 15, 1 <-> 14, ...</span></div>
<div class="line"><a name="l00100"></a><span class="lineno"> 100</span>  K otherK = shfl_xor(k, 2 * L - 1);</div>
<div class="line"><a name="l00101"></a><span class="lineno"> 101</span>  V otherV = shfl_xor(v, 2 * L - 1);</div>
<div class="line"><a name="l00102"></a><span class="lineno"> 102</span> </div>
<div class="line"><a name="l00103"></a><span class="lineno"> 103</span>  <span class="comment">// Whether we are the lesser thread in the exchange</span></div>
<div class="line"><a name="l00104"></a><span class="lineno"> 104</span>  <span class="keywordtype">bool</span> small = !(laneId & L);</div>
<div class="line"><a name="l00105"></a><span class="lineno"> 105</span> </div>
<div class="line"><a name="l00106"></a><span class="lineno"> 106</span>  <span class="keywordflow">if</span> (Dir) {</div>
<div class="line"><a name="l00107"></a><span class="lineno"> 107</span>  <span class="comment">// See the comment above how performing both of these</span></div>
<div class="line"><a name="l00108"></a><span class="lineno"> 108</span>  <span class="comment">// comparisons in the warp seems to win out over the</span></div>
<div class="line"><a name="l00109"></a><span class="lineno"> 109</span>  <span class="comment">// alternatives in practice</span></div>
<div class="line"><a name="l00110"></a><span class="lineno"> 110</span>  <span class="keywordtype">bool</span> s = small ? Comp::gt(k, otherK) : Comp::lt(k, otherK);</div>
<div class="line"><a name="l00111"></a><span class="lineno"> 111</span>  assign(s, k, otherK);</div>
<div class="line"><a name="l00112"></a><span class="lineno"> 112</span>  assign(s, v, otherV);</div>
<div class="line"><a name="l00113"></a><span class="lineno"> 113</span> </div>
<div class="line"><a name="l00114"></a><span class="lineno"> 114</span>  } <span class="keywordflow">else</span> {</div>
<div class="line"><a name="l00115"></a><span class="lineno"> 115</span>  <span class="keywordtype">bool</span> s = small ? Comp::lt(k, otherK) : Comp::gt(k, otherK);</div>
<div class="line"><a name="l00116"></a><span class="lineno"> 116</span>  assign(s, k, otherK);</div>
<div class="line"><a name="l00117"></a><span class="lineno"> 117</span>  assign(s, v, otherV);</div>
<div class="line"><a name="l00118"></a><span class="lineno"> 118</span>  }</div>
<div class="line"><a name="l00119"></a><span class="lineno"> 119</span>  }</div>
<div class="line"><a name="l00120"></a><span class="lineno"> 120</span> </div>
<div class="line"><a name="l00121"></a><span class="lineno"> 121</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00122"></a><span class="lineno"> 122</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> stride = IsBitonic ? L : L / 2; stride > 0; stride /= 2) {</div>
<div class="line"><a name="l00123"></a><span class="lineno"> 123</span>  K otherK = shfl_xor(k, stride);</div>
<div class="line"><a name="l00124"></a><span class="lineno"> 124</span>  V otherV = shfl_xor(v, stride);</div>
<div class="line"><a name="l00125"></a><span class="lineno"> 125</span> </div>
<div class="line"><a name="l00126"></a><span class="lineno"> 126</span>  <span class="comment">// Whether we are the lesser thread in the exchange</span></div>
<div class="line"><a name="l00127"></a><span class="lineno"> 127</span>  <span class="keywordtype">bool</span> small = !(laneId & stride);</div>
<div class="line"><a name="l00128"></a><span class="lineno"> 128</span> </div>
<div class="line"><a name="l00129"></a><span class="lineno"> 129</span>  <span class="keywordflow">if</span> (Dir) {</div>
<div class="line"><a name="l00130"></a><span class="lineno"> 130</span>  <span class="keywordtype">bool</span> s = small ? Comp::gt(k, otherK) : Comp::lt(k, otherK);</div>
<div class="line"><a name="l00131"></a><span class="lineno"> 131</span>  assign(s, k, otherK);</div>
<div class="line"><a name="l00132"></a><span class="lineno"> 132</span>  assign(s, v, otherV);</div>
<div class="line"><a name="l00133"></a><span class="lineno"> 133</span> </div>
<div class="line"><a name="l00134"></a><span class="lineno"> 134</span>  } <span class="keywordflow">else</span> {</div>
<div class="line"><a name="l00135"></a><span class="lineno"> 135</span>  <span class="keywordtype">bool</span> s = small ? Comp::lt(k, otherK) : Comp::gt(k, otherK);</div>
<div class="line"><a name="l00136"></a><span class="lineno"> 136</span>  assign(s, k, otherK);</div>
<div class="line"><a name="l00137"></a><span class="lineno"> 137</span>  assign(s, v, otherV);</div>
<div class="line"><a name="l00138"></a><span class="lineno"> 138</span>  }</div>
<div class="line"><a name="l00139"></a><span class="lineno"> 139</span>  }</div>
<div class="line"><a name="l00140"></a><span class="lineno"> 140</span> }</div>
<div class="line"><a name="l00141"></a><span class="lineno"> 141</span> </div>
<div class="line"><a name="l00142"></a><span class="lineno"> 142</span> <span class="comment">// Template for performing a bitonic merge of an arbitrary set of</span></div>
<div class="line"><a name="l00143"></a><span class="lineno"> 143</span> <span class="comment">// registers</span></div>
<div class="line"><a name="l00144"></a><span class="lineno"> 144</span> <span class="keyword">template</span> <<span class="keyword">typename</span> K, <span class="keyword">typename</span> V, <span class="keywordtype">int</span> N,</div>
<div class="line"><a name="l00145"></a><span class="lineno"> 145</span>  <span class="keywordtype">bool</span> Dir, <span class="keyword">typename</span> Comp, <span class="keywordtype">bool</span> Low, <span class="keywordtype">bool</span> Pow2></div>
<div class="line"><a name="l00146"></a><span class="lineno"><a class="line" href="structfaiss_1_1gpu_1_1BitonicMergeStep.html"> 146</a></span> <span class="keyword">struct </span><a class="code" href="structfaiss_1_1gpu_1_1BitonicMergeStep.html">BitonicMergeStep</a> {</div>
<div class="line"><a name="l00147"></a><span class="lineno"> 147</span> };</div>
<div class="line"><a name="l00148"></a><span class="lineno"> 148</span> </div>
<div class="line"><a name="l00149"></a><span class="lineno"> 149</span> <span class="comment">//</span></div>
<div class="line"><a name="l00150"></a><span class="lineno"> 150</span> <span class="comment">// Power-of-2 merge specialization</span></div>
<div class="line"><a name="l00151"></a><span class="lineno"> 151</span> <span class="comment">//</span></div>
<div class="line"><a name="l00152"></a><span class="lineno"> 152</span> </div>
<div class="line"><a name="l00153"></a><span class="lineno"> 153</span> <span class="comment">// All merges eventually call this</span></div>
<div class="line"><a name="l00154"></a><span class="lineno"> 154</span> <span class="keyword">template</span> <<span class="keyword">typename</span> K, <span class="keyword">typename</span> V, <span class="keywordtype">bool</span> Dir, <span class="keyword">typename</span> Comp, <span class="keywordtype">bool</span> Low></div>
<div class="line"><a name="l00155"></a><span class="lineno"><a class="line" href="structfaiss_1_1gpu_1_1BitonicMergeStep_3_01K_00_01V_00_011_00_01Dir_00_01Comp_00_01Low_00_01true_01_4.html"> 155</a></span> <span class="keyword">struct </span><a class="code" href="structfaiss_1_1gpu_1_1BitonicMergeStep.html">BitonicMergeStep</a><K, V, 1, Dir, Comp, Low, true> {</div>
<div class="line"><a name="l00156"></a><span class="lineno"> 156</span>  <span class="keyword">static</span> <span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> merge(K k[1], V v[1]) {</div>
<div class="line"><a name="l00157"></a><span class="lineno"> 157</span>  <span class="comment">// Use warp shuffles</span></div>
<div class="line"><a name="l00158"></a><span class="lineno"> 158</span>  warpBitonicMergeLE16<K, V, 16, Dir, Comp, true>(k[0], v[0]);</div>
<div class="line"><a name="l00159"></a><span class="lineno"> 159</span>  }</div>
<div class="line"><a name="l00160"></a><span class="lineno"> 160</span> };</div>
<div class="line"><a name="l00161"></a><span class="lineno"> 161</span> </div>
<div class="line"><a name="l00162"></a><span class="lineno"> 162</span> <span class="keyword">template</span> <<span class="keyword">typename</span> K, <span class="keyword">typename</span> V, <span class="keywordtype">int</span> N, <span class="keywordtype">bool</span> Dir, <span class="keyword">typename</span> Comp, <span class="keywordtype">bool</span> Low></div>
<div class="line"><a name="l00163"></a><span class="lineno"><a class="line" href="structfaiss_1_1gpu_1_1BitonicMergeStep_3_01K_00_01V_00_01N_00_01Dir_00_01Comp_00_01Low_00_01true_01_4.html"> 163</a></span> <span class="keyword">struct </span><a class="code" href="structfaiss_1_1gpu_1_1BitonicMergeStep.html">BitonicMergeStep</a><K, V, N, Dir, Comp, Low, true> {</div>
<div class="line"><a name="l00164"></a><span class="lineno"> 164</span>  <span class="keyword">static</span> <span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> merge(K k[N], V v[N]) {</div>
<div class="line"><a name="l00165"></a><span class="lineno"> 165</span>  static_assert(utils::isPowerOf2(N), <span class="stringliteral">"must be power of 2"</span>);</div>
<div class="line"><a name="l00166"></a><span class="lineno"> 166</span>  static_assert(N > 1, <span class="stringliteral">"must be N > 1"</span>);</div>
<div class="line"><a name="l00167"></a><span class="lineno"> 167</span> </div>
<div class="line"><a name="l00168"></a><span class="lineno"> 168</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00169"></a><span class="lineno"> 169</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < N / 2; ++i) {</div>
<div class="line"><a name="l00170"></a><span class="lineno"> 170</span>  K& ka = k[i];</div>
<div class="line"><a name="l00171"></a><span class="lineno"> 171</span>  V& va = v[i];</div>
<div class="line"><a name="l00172"></a><span class="lineno"> 172</span> </div>
<div class="line"><a name="l00173"></a><span class="lineno"> 173</span>  K& kb = k[i + N / 2];</div>
<div class="line"><a name="l00174"></a><span class="lineno"> 174</span>  V& vb = v[i + N / 2];</div>
<div class="line"><a name="l00175"></a><span class="lineno"> 175</span> </div>
<div class="line"><a name="l00176"></a><span class="lineno"> 176</span>  <span class="keywordtype">bool</span> s = Dir ? Comp::gt(ka, kb) : Comp::lt(ka, kb);</div>
<div class="line"><a name="l00177"></a><span class="lineno"> 177</span>  swap(s, ka, kb);</div>
<div class="line"><a name="l00178"></a><span class="lineno"> 178</span>  swap(s, va, vb);</div>
<div class="line"><a name="l00179"></a><span class="lineno"> 179</span>  }</div>
<div class="line"><a name="l00180"></a><span class="lineno"> 180</span> </div>
<div class="line"><a name="l00181"></a><span class="lineno"> 181</span>  {</div>
<div class="line"><a name="l00182"></a><span class="lineno"> 182</span>  K newK[N / 2];</div>
<div class="line"><a name="l00183"></a><span class="lineno"> 183</span>  V newV[N / 2];</div>
<div class="line"><a name="l00184"></a><span class="lineno"> 184</span> </div>
<div class="line"><a name="l00185"></a><span class="lineno"> 185</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00186"></a><span class="lineno"> 186</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < N / 2; ++i) {</div>
<div class="line"><a name="l00187"></a><span class="lineno"> 187</span>  newK[i] = k[i];</div>
<div class="line"><a name="l00188"></a><span class="lineno"> 188</span>  newV[i] = v[i];</div>
<div class="line"><a name="l00189"></a><span class="lineno"> 189</span>  }</div>
<div class="line"><a name="l00190"></a><span class="lineno"> 190</span> </div>
<div class="line"><a name="l00191"></a><span class="lineno"> 191</span>  <a class="code" href="structfaiss_1_1gpu_1_1BitonicMergeStep.html">BitonicMergeStep</a><K, V, N / 2, Dir, Comp, <span class="keyword">true</span>, <span class="keyword">true</span>>::merge(newK, newV);</div>
<div class="line"><a name="l00192"></a><span class="lineno"> 192</span> </div>
<div class="line"><a name="l00193"></a><span class="lineno"> 193</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00194"></a><span class="lineno"> 194</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < N / 2; ++i) {</div>
<div class="line"><a name="l00195"></a><span class="lineno"> 195</span>  k[i] = newK[i];</div>
<div class="line"><a name="l00196"></a><span class="lineno"> 196</span>  v[i] = newV[i];</div>
<div class="line"><a name="l00197"></a><span class="lineno"> 197</span>  }</div>
<div class="line"><a name="l00198"></a><span class="lineno"> 198</span>  }</div>
<div class="line"><a name="l00199"></a><span class="lineno"> 199</span> </div>
<div class="line"><a name="l00200"></a><span class="lineno"> 200</span>  {</div>
<div class="line"><a name="l00201"></a><span class="lineno"> 201</span>  K newK[N / 2];</div>
<div class="line"><a name="l00202"></a><span class="lineno"> 202</span>  V newV[N / 2];</div>
<div class="line"><a name="l00203"></a><span class="lineno"> 203</span> </div>
<div class="line"><a name="l00204"></a><span class="lineno"> 204</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00205"></a><span class="lineno"> 205</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < N / 2; ++i) {</div>
<div class="line"><a name="l00206"></a><span class="lineno"> 206</span>  newK[i] = k[i + N / 2];</div>
<div class="line"><a name="l00207"></a><span class="lineno"> 207</span>  newV[i] = v[i + N / 2];</div>
<div class="line"><a name="l00208"></a><span class="lineno"> 208</span>  }</div>
<div class="line"><a name="l00209"></a><span class="lineno"> 209</span> </div>
<div class="line"><a name="l00210"></a><span class="lineno"> 210</span>  <a class="code" href="structfaiss_1_1gpu_1_1BitonicMergeStep.html">BitonicMergeStep</a><K, V, N / 2, Dir, Comp, <span class="keyword">false</span>, <span class="keyword">true</span>>::merge(newK, newV);</div>
<div class="line"><a name="l00211"></a><span class="lineno"> 211</span> </div>
<div class="line"><a name="l00212"></a><span class="lineno"> 212</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00213"></a><span class="lineno"> 213</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < N / 2; ++i) {</div>
<div class="line"><a name="l00214"></a><span class="lineno"> 214</span>  k[i + N / 2] = newK[i];</div>
<div class="line"><a name="l00215"></a><span class="lineno"> 215</span>  v[i + N / 2] = newV[i];</div>
<div class="line"><a name="l00216"></a><span class="lineno"> 216</span>  }</div>
<div class="line"><a name="l00217"></a><span class="lineno"> 217</span>  }</div>
<div class="line"><a name="l00218"></a><span class="lineno"> 218</span>  }</div>
<div class="line"><a name="l00219"></a><span class="lineno"> 219</span> };</div>
<div class="line"><a name="l00220"></a><span class="lineno"> 220</span> </div>
<div class="line"><a name="l00221"></a><span class="lineno"> 221</span> <span class="comment">//</span></div>
<div class="line"><a name="l00222"></a><span class="lineno"> 222</span> <span class="comment">// Non-power-of-2 merge specialization</span></div>
<div class="line"><a name="l00223"></a><span class="lineno"> 223</span> <span class="comment">//</span></div>
<div class="line"><a name="l00224"></a><span class="lineno"> 224</span> </div>
<div class="line"><a name="l00225"></a><span class="lineno"> 225</span> <span class="comment">// Low recursion</span></div>
<div class="line"><a name="l00226"></a><span class="lineno"> 226</span> <span class="keyword">template</span> <<span class="keyword">typename</span> K, <span class="keyword">typename</span> V, <span class="keywordtype">int</span> N, <span class="keywordtype">bool</span> Dir, <span class="keyword">typename</span> Comp></div>
<div class="line"><a name="l00227"></a><span class="lineno"><a class="line" href="structfaiss_1_1gpu_1_1BitonicMergeStep_3_01K_00_01V_00_01N_00_01Dir_00_01Comp_00_01true_00_01false_01_4.html"> 227</a></span> <span class="keyword">struct </span><a class="code" href="structfaiss_1_1gpu_1_1BitonicMergeStep.html">BitonicMergeStep</a><K, V, N, Dir, Comp, true, false> {</div>
<div class="line"><a name="l00228"></a><span class="lineno"> 228</span>  <span class="keyword">static</span> <span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> merge(K k[N], V v[N]) {</div>
<div class="line"><a name="l00229"></a><span class="lineno"> 229</span>  static_assert(!utils::isPowerOf2(N), <span class="stringliteral">"must be non-power-of-2"</span>);</div>
<div class="line"><a name="l00230"></a><span class="lineno"> 230</span>  static_assert(N >= 3, <span class="stringliteral">"must be N >= 3"</span>);</div>
<div class="line"><a name="l00231"></a><span class="lineno"> 231</span> </div>
<div class="line"><a name="l00232"></a><span class="lineno"> 232</span>  constexpr <span class="keywordtype">int</span> kNextHighestPowerOf2 = utils::nextHighestPowerOf2(N);</div>
<div class="line"><a name="l00233"></a><span class="lineno"> 233</span> </div>
<div class="line"><a name="l00234"></a><span class="lineno"> 234</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00235"></a><span class="lineno"> 235</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < N - kNextHighestPowerOf2 / 2; ++i) {</div>
<div class="line"><a name="l00236"></a><span class="lineno"> 236</span>  K& ka = k[i];</div>
<div class="line"><a name="l00237"></a><span class="lineno"> 237</span>  V& va = v[i];</div>
<div class="line"><a name="l00238"></a><span class="lineno"> 238</span> </div>
<div class="line"><a name="l00239"></a><span class="lineno"> 239</span>  K& kb = k[i + kNextHighestPowerOf2 / 2];</div>
<div class="line"><a name="l00240"></a><span class="lineno"> 240</span>  V& vb = v[i + kNextHighestPowerOf2 / 2];</div>
<div class="line"><a name="l00241"></a><span class="lineno"> 241</span> </div>
<div class="line"><a name="l00242"></a><span class="lineno"> 242</span>  <span class="keywordtype">bool</span> s = Dir ? Comp::gt(ka, kb) : Comp::lt(ka, kb);</div>
<div class="line"><a name="l00243"></a><span class="lineno"> 243</span>  swap(s, ka, kb);</div>
<div class="line"><a name="l00244"></a><span class="lineno"> 244</span>  swap(s, va, vb);</div>
<div class="line"><a name="l00245"></a><span class="lineno"> 245</span>  }</div>
<div class="line"><a name="l00246"></a><span class="lineno"> 246</span> </div>
<div class="line"><a name="l00247"></a><span class="lineno"> 247</span>  constexpr <span class="keywordtype">int</span> kLowSize = N - kNextHighestPowerOf2 / 2;</div>
<div class="line"><a name="l00248"></a><span class="lineno"> 248</span>  constexpr <span class="keywordtype">int</span> kHighSize = kNextHighestPowerOf2 / 2;</div>
<div class="line"><a name="l00249"></a><span class="lineno"> 249</span>  {</div>
<div class="line"><a name="l00250"></a><span class="lineno"> 250</span>  K newK[kLowSize];</div>
<div class="line"><a name="l00251"></a><span class="lineno"> 251</span>  V newV[kLowSize];</div>
<div class="line"><a name="l00252"></a><span class="lineno"> 252</span> </div>
<div class="line"><a name="l00253"></a><span class="lineno"> 253</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00254"></a><span class="lineno"> 254</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kLowSize; ++i) {</div>
<div class="line"><a name="l00255"></a><span class="lineno"> 255</span>  newK[i] = k[i];</div>
<div class="line"><a name="l00256"></a><span class="lineno"> 256</span>  newV[i] = v[i];</div>
<div class="line"><a name="l00257"></a><span class="lineno"> 257</span>  }</div>
<div class="line"><a name="l00258"></a><span class="lineno"> 258</span> </div>
<div class="line"><a name="l00259"></a><span class="lineno"> 259</span>  constexpr <span class="keywordtype">bool</span> kLowIsPowerOf2 =</div>
<div class="line"><a name="l00260"></a><span class="lineno"> 260</span>  utils::isPowerOf2(N - kNextHighestPowerOf2 / 2);</div>
<div class="line"><a name="l00261"></a><span class="lineno"> 261</span>  <span class="comment">// FIXME: compiler doesn't like this expression? compiler bug?</span></div>
<div class="line"><a name="l00262"></a><span class="lineno"> 262</span> <span class="comment">// constexpr bool kLowIsPowerOf2 = utils::isPowerOf2(kLowSize);</span></div>
<div class="line"><a name="l00263"></a><span class="lineno"> 263</span>  <a class="code" href="structfaiss_1_1gpu_1_1BitonicMergeStep.html">BitonicMergeStep</a><K, V, kLowSize, Dir, Comp,</div>
<div class="line"><a name="l00264"></a><span class="lineno"> 264</span>  <span class="keyword">true</span>, <span class="comment">// low</span></div>
<div class="line"><a name="l00265"></a><span class="lineno"> 265</span>  kLowIsPowerOf2>::merge(newK, newV);</div>
<div class="line"><a name="l00266"></a><span class="lineno"> 266</span> </div>
<div class="line"><a name="l00267"></a><span class="lineno"> 267</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00268"></a><span class="lineno"> 268</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kLowSize; ++i) {</div>
<div class="line"><a name="l00269"></a><span class="lineno"> 269</span>  k[i] = newK[i];</div>
<div class="line"><a name="l00270"></a><span class="lineno"> 270</span>  v[i] = newV[i];</div>
<div class="line"><a name="l00271"></a><span class="lineno"> 271</span>  }</div>
<div class="line"><a name="l00272"></a><span class="lineno"> 272</span>  }</div>
<div class="line"><a name="l00273"></a><span class="lineno"> 273</span> </div>
<div class="line"><a name="l00274"></a><span class="lineno"> 274</span>  {</div>
<div class="line"><a name="l00275"></a><span class="lineno"> 275</span>  K newK[kHighSize];</div>
<div class="line"><a name="l00276"></a><span class="lineno"> 276</span>  V newV[kHighSize];</div>
<div class="line"><a name="l00277"></a><span class="lineno"> 277</span> </div>
<div class="line"><a name="l00278"></a><span class="lineno"> 278</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00279"></a><span class="lineno"> 279</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kHighSize; ++i) {</div>
<div class="line"><a name="l00280"></a><span class="lineno"> 280</span>  newK[i] = k[i + kLowSize];</div>
<div class="line"><a name="l00281"></a><span class="lineno"> 281</span>  newV[i] = v[i + kLowSize];</div>
<div class="line"><a name="l00282"></a><span class="lineno"> 282</span>  }</div>
<div class="line"><a name="l00283"></a><span class="lineno"> 283</span> </div>
<div class="line"><a name="l00284"></a><span class="lineno"> 284</span>  constexpr <span class="keywordtype">bool</span> kHighIsPowerOf2 =</div>
<div class="line"><a name="l00285"></a><span class="lineno"> 285</span>  utils::isPowerOf2(kNextHighestPowerOf2 / 2);</div>
<div class="line"><a name="l00286"></a><span class="lineno"> 286</span>  <span class="comment">// FIXME: compiler doesn't like this expression? compiler bug?</span></div>
<div class="line"><a name="l00287"></a><span class="lineno"> 287</span> <span class="comment">// constexpr bool kHighIsPowerOf2 = utils::isPowerOf2(kHighSize);</span></div>
<div class="line"><a name="l00288"></a><span class="lineno"> 288</span>  <a class="code" href="structfaiss_1_1gpu_1_1BitonicMergeStep.html">BitonicMergeStep</a><K, V, kHighSize, Dir, Comp,</div>
<div class="line"><a name="l00289"></a><span class="lineno"> 289</span>  <span class="keyword">false</span>, <span class="comment">// high</span></div>
<div class="line"><a name="l00290"></a><span class="lineno"> 290</span>  kHighIsPowerOf2>::merge(newK, newV);</div>
<div class="line"><a name="l00291"></a><span class="lineno"> 291</span> </div>
<div class="line"><a name="l00292"></a><span class="lineno"> 292</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00293"></a><span class="lineno"> 293</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kHighSize; ++i) {</div>
<div class="line"><a name="l00294"></a><span class="lineno"> 294</span>  k[i + kLowSize] = newK[i];</div>
<div class="line"><a name="l00295"></a><span class="lineno"> 295</span>  v[i + kLowSize] = newV[i];</div>
<div class="line"><a name="l00296"></a><span class="lineno"> 296</span>  }</div>
<div class="line"><a name="l00297"></a><span class="lineno"> 297</span>  }</div>
<div class="line"><a name="l00298"></a><span class="lineno"> 298</span>  }</div>
<div class="line"><a name="l00299"></a><span class="lineno"> 299</span> };</div>
<div class="line"><a name="l00300"></a><span class="lineno"> 300</span> </div>
<div class="line"><a name="l00301"></a><span class="lineno"> 301</span> <span class="comment">// High recursion</span></div>
<div class="line"><a name="l00302"></a><span class="lineno"> 302</span> <span class="keyword">template</span> <<span class="keyword">typename</span> K, <span class="keyword">typename</span> V, <span class="keywordtype">int</span> N, <span class="keywordtype">bool</span> Dir, <span class="keyword">typename</span> Comp></div>
<div class="line"><a name="l00303"></a><span class="lineno"><a class="line" href="structfaiss_1_1gpu_1_1BitonicMergeStep_3_01K_00_01V_00_01N_00_01Dir_00_01Comp_00_01false_00_01false_01_4.html"> 303</a></span> <span class="keyword">struct </span><a class="code" href="structfaiss_1_1gpu_1_1BitonicMergeStep.html">BitonicMergeStep</a><K, V, N, Dir, Comp, false, false> {</div>
<div class="line"><a name="l00304"></a><span class="lineno"> 304</span>  <span class="keyword">static</span> <span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> merge(K k[N], V v[N]) {</div>
<div class="line"><a name="l00305"></a><span class="lineno"> 305</span>  static_assert(!utils::isPowerOf2(N), <span class="stringliteral">"must be non-power-of-2"</span>);</div>
<div class="line"><a name="l00306"></a><span class="lineno"> 306</span>  static_assert(N >= 3, <span class="stringliteral">"must be N >= 3"</span>);</div>
<div class="line"><a name="l00307"></a><span class="lineno"> 307</span> </div>
<div class="line"><a name="l00308"></a><span class="lineno"> 308</span>  constexpr <span class="keywordtype">int</span> kNextHighestPowerOf2 = utils::nextHighestPowerOf2(N);</div>
<div class="line"><a name="l00309"></a><span class="lineno"> 309</span> </div>
<div class="line"><a name="l00310"></a><span class="lineno"> 310</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00311"></a><span class="lineno"> 311</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < N - kNextHighestPowerOf2 / 2; ++i) {</div>
<div class="line"><a name="l00312"></a><span class="lineno"> 312</span>  K& ka = k[i];</div>
<div class="line"><a name="l00313"></a><span class="lineno"> 313</span>  V& va = v[i];</div>
<div class="line"><a name="l00314"></a><span class="lineno"> 314</span> </div>
<div class="line"><a name="l00315"></a><span class="lineno"> 315</span>  K& kb = k[i + kNextHighestPowerOf2 / 2];</div>
<div class="line"><a name="l00316"></a><span class="lineno"> 316</span>  V& vb = v[i + kNextHighestPowerOf2 / 2];</div>
<div class="line"><a name="l00317"></a><span class="lineno"> 317</span> </div>
<div class="line"><a name="l00318"></a><span class="lineno"> 318</span>  <span class="keywordtype">bool</span> s = Dir ? Comp::gt(ka, kb) : Comp::lt(ka, kb);</div>
<div class="line"><a name="l00319"></a><span class="lineno"> 319</span>  swap(s, ka, kb);</div>
<div class="line"><a name="l00320"></a><span class="lineno"> 320</span>  swap(s, va, vb);</div>
<div class="line"><a name="l00321"></a><span class="lineno"> 321</span>  }</div>
<div class="line"><a name="l00322"></a><span class="lineno"> 322</span> </div>
<div class="line"><a name="l00323"></a><span class="lineno"> 323</span>  constexpr <span class="keywordtype">int</span> kLowSize = kNextHighestPowerOf2 / 2;</div>
<div class="line"><a name="l00324"></a><span class="lineno"> 324</span>  constexpr <span class="keywordtype">int</span> kHighSize = N - kNextHighestPowerOf2 / 2;</div>
<div class="line"><a name="l00325"></a><span class="lineno"> 325</span>  {</div>
<div class="line"><a name="l00326"></a><span class="lineno"> 326</span>  K newK[kLowSize];</div>
<div class="line"><a name="l00327"></a><span class="lineno"> 327</span>  V newV[kLowSize];</div>
<div class="line"><a name="l00328"></a><span class="lineno"> 328</span> </div>
<div class="line"><a name="l00329"></a><span class="lineno"> 329</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00330"></a><span class="lineno"> 330</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kLowSize; ++i) {</div>
<div class="line"><a name="l00331"></a><span class="lineno"> 331</span>  newK[i] = k[i];</div>
<div class="line"><a name="l00332"></a><span class="lineno"> 332</span>  newV[i] = v[i];</div>
<div class="line"><a name="l00333"></a><span class="lineno"> 333</span>  }</div>
<div class="line"><a name="l00334"></a><span class="lineno"> 334</span> </div>
<div class="line"><a name="l00335"></a><span class="lineno"> 335</span>  constexpr <span class="keywordtype">bool</span> kLowIsPowerOf2 =</div>
<div class="line"><a name="l00336"></a><span class="lineno"> 336</span>  utils::isPowerOf2(kNextHighestPowerOf2 / 2);</div>
<div class="line"><a name="l00337"></a><span class="lineno"> 337</span>  <span class="comment">// FIXME: compiler doesn't like this expression? compiler bug?</span></div>
<div class="line"><a name="l00338"></a><span class="lineno"> 338</span> <span class="comment">// constexpr bool kLowIsPowerOf2 = utils::isPowerOf2(kLowSize);</span></div>
<div class="line"><a name="l00339"></a><span class="lineno"> 339</span>  <a class="code" href="structfaiss_1_1gpu_1_1BitonicMergeStep.html">BitonicMergeStep</a><K, V, kLowSize, Dir, Comp,</div>
<div class="line"><a name="l00340"></a><span class="lineno"> 340</span>  <span class="keyword">true</span>, <span class="comment">// low</span></div>
<div class="line"><a name="l00341"></a><span class="lineno"> 341</span>  kLowIsPowerOf2>::merge(newK, newV);</div>
<div class="line"><a name="l00342"></a><span class="lineno"> 342</span> </div>
<div class="line"><a name="l00343"></a><span class="lineno"> 343</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00344"></a><span class="lineno"> 344</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kLowSize; ++i) {</div>
<div class="line"><a name="l00345"></a><span class="lineno"> 345</span>  k[i] = newK[i];</div>
<div class="line"><a name="l00346"></a><span class="lineno"> 346</span>  v[i] = newV[i];</div>
<div class="line"><a name="l00347"></a><span class="lineno"> 347</span>  }</div>
<div class="line"><a name="l00348"></a><span class="lineno"> 348</span>  }</div>
<div class="line"><a name="l00349"></a><span class="lineno"> 349</span> </div>
<div class="line"><a name="l00350"></a><span class="lineno"> 350</span>  {</div>
<div class="line"><a name="l00351"></a><span class="lineno"> 351</span>  K newK[kHighSize];</div>
<div class="line"><a name="l00352"></a><span class="lineno"> 352</span>  V newV[kHighSize];</div>
<div class="line"><a name="l00353"></a><span class="lineno"> 353</span> </div>
<div class="line"><a name="l00354"></a><span class="lineno"> 354</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00355"></a><span class="lineno"> 355</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kHighSize; ++i) {</div>
<div class="line"><a name="l00356"></a><span class="lineno"> 356</span>  newK[i] = k[i + kLowSize];</div>
<div class="line"><a name="l00357"></a><span class="lineno"> 357</span>  newV[i] = v[i + kLowSize];</div>
<div class="line"><a name="l00358"></a><span class="lineno"> 358</span>  }</div>
<div class="line"><a name="l00359"></a><span class="lineno"> 359</span> </div>
<div class="line"><a name="l00360"></a><span class="lineno"> 360</span>  constexpr <span class="keywordtype">bool</span> kHighIsPowerOf2 =</div>
<div class="line"><a name="l00361"></a><span class="lineno"> 361</span>  utils::isPowerOf2(N - kNextHighestPowerOf2 / 2);</div>
<div class="line"><a name="l00362"></a><span class="lineno"> 362</span>  <span class="comment">// FIXME: compiler doesn't like this expression? compiler bug?</span></div>
<div class="line"><a name="l00363"></a><span class="lineno"> 363</span> <span class="comment">// constexpr bool kHighIsPowerOf2 = utils::isPowerOf2(kHighSize);</span></div>
<div class="line"><a name="l00364"></a><span class="lineno"> 364</span>  <a class="code" href="structfaiss_1_1gpu_1_1BitonicMergeStep.html">BitonicMergeStep</a><K, V, kHighSize, Dir, Comp,</div>
<div class="line"><a name="l00365"></a><span class="lineno"> 365</span>  <span class="keyword">false</span>, <span class="comment">// high</span></div>
<div class="line"><a name="l00366"></a><span class="lineno"> 366</span>  kHighIsPowerOf2>::merge(newK, newV);</div>
<div class="line"><a name="l00367"></a><span class="lineno"> 367</span> </div>
<div class="line"><a name="l00368"></a><span class="lineno"> 368</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00369"></a><span class="lineno"> 369</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kHighSize; ++i) {</div>
<div class="line"><a name="l00370"></a><span class="lineno"> 370</span>  k[i + kLowSize] = newK[i];</div>
<div class="line"><a name="l00371"></a><span class="lineno"> 371</span>  v[i + kLowSize] = newV[i];</div>
<div class="line"><a name="l00372"></a><span class="lineno"> 372</span>  }</div>
<div class="line"><a name="l00373"></a><span class="lineno"> 373</span>  }</div>
<div class="line"><a name="l00374"></a><span class="lineno"> 374</span>  }</div>
<div class="line"><a name="l00375"></a><span class="lineno"> 375</span> };</div>
<div class="line"><a name="l00376"></a><span class="lineno"> 376</span> <span class="comment"></span></div>
<div class="line"><a name="l00377"></a><span class="lineno"> 377</span> <span class="comment">/// Merges two sets of registers across the warp of any size;</span></div>
<div class="line"><a name="l00378"></a><span class="lineno"> 378</span> <span class="comment">/// i.e., merges a sorted k/v list of size kWarpSize * N1 with a</span></div>
<div class="line"><a name="l00379"></a><span class="lineno"> 379</span> <span class="comment">/// sorted k/v list of size kWarpSize * N2, where N1 and N2 are any</span></div>
<div class="line"><a name="l00380"></a><span class="lineno"> 380</span> <span class="comment">/// value >= 1</span></div>
<div class="line"><a name="l00381"></a><span class="lineno"> 381</span> <span class="comment"></span><span class="keyword">template</span> <<span class="keyword">typename</span> K,</div>
<div class="line"><a name="l00382"></a><span class="lineno"> 382</span>  <span class="keyword">typename</span> V,</div>
<div class="line"><a name="l00383"></a><span class="lineno"> 383</span>  <span class="keywordtype">int</span> N1,</div>
<div class="line"><a name="l00384"></a><span class="lineno"> 384</span>  <span class="keywordtype">int</span> N2,</div>
<div class="line"><a name="l00385"></a><span class="lineno"> 385</span>  <span class="keywordtype">bool</span> Dir,</div>
<div class="line"><a name="l00386"></a><span class="lineno"> 386</span>  <span class="keyword">typename</span> Comp,</div>
<div class="line"><a name="l00387"></a><span class="lineno"> 387</span>  <span class="keywordtype">bool</span> FullMerge = <span class="keyword">true</span>></div>
<div class="line"><a name="l00388"></a><span class="lineno"> 388</span> <span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> warpMergeAnyRegisters(K k1[N1], V v1[N1],</div>
<div class="line"><a name="l00389"></a><span class="lineno"> 389</span>  K k2[N2], V v2[N2]) {</div>
<div class="line"><a name="l00390"></a><span class="lineno"> 390</span>  constexpr <span class="keywordtype">int</span> kSmallestN = N1 < N2 ? N1 : N2;</div>
<div class="line"><a name="l00391"></a><span class="lineno"> 391</span> </div>
<div class="line"><a name="l00392"></a><span class="lineno"> 392</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00393"></a><span class="lineno"> 393</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kSmallestN; ++i) {</div>
<div class="line"><a name="l00394"></a><span class="lineno"> 394</span>  K& ka = k1[N1 - 1 - i];</div>
<div class="line"><a name="l00395"></a><span class="lineno"> 395</span>  V& va = v1[N1 - 1 - i];</div>
<div class="line"><a name="l00396"></a><span class="lineno"> 396</span> </div>
<div class="line"><a name="l00397"></a><span class="lineno"> 397</span>  K& kb = k2[i];</div>
<div class="line"><a name="l00398"></a><span class="lineno"> 398</span>  V& vb = v2[i];</div>
<div class="line"><a name="l00399"></a><span class="lineno"> 399</span> </div>
<div class="line"><a name="l00400"></a><span class="lineno"> 400</span>  K otherKa;</div>
<div class="line"><a name="l00401"></a><span class="lineno"> 401</span>  V otherVa;</div>
<div class="line"><a name="l00402"></a><span class="lineno"> 402</span> </div>
<div class="line"><a name="l00403"></a><span class="lineno"> 403</span>  <span class="keywordflow">if</span> (FullMerge) {</div>
<div class="line"><a name="l00404"></a><span class="lineno"> 404</span>  <span class="comment">// We need the other values</span></div>
<div class="line"><a name="l00405"></a><span class="lineno"> 405</span>  otherKa = shfl_xor(ka, kWarpSize - 1);</div>
<div class="line"><a name="l00406"></a><span class="lineno"> 406</span>  otherVa = shfl_xor(va, kWarpSize - 1);</div>
<div class="line"><a name="l00407"></a><span class="lineno"> 407</span>  }</div>
<div class="line"><a name="l00408"></a><span class="lineno"> 408</span> </div>
<div class="line"><a name="l00409"></a><span class="lineno"> 409</span>  K otherKb = shfl_xor(kb, kWarpSize - 1);</div>
<div class="line"><a name="l00410"></a><span class="lineno"> 410</span>  V otherVb = shfl_xor(vb, kWarpSize - 1);</div>
<div class="line"><a name="l00411"></a><span class="lineno"> 411</span> </div>
<div class="line"><a name="l00412"></a><span class="lineno"> 412</span>  <span class="comment">// ka is always first in the list, so we needn't use our lane</span></div>
<div class="line"><a name="l00413"></a><span class="lineno"> 413</span>  <span class="comment">// in this comparison</span></div>
<div class="line"><a name="l00414"></a><span class="lineno"> 414</span>  <span class="keywordtype">bool</span> swapa = Dir ? Comp::gt(ka, otherKb) : Comp::lt(ka, otherKb);</div>
<div class="line"><a name="l00415"></a><span class="lineno"> 415</span>  assign(swapa, ka, otherKb);</div>
<div class="line"><a name="l00416"></a><span class="lineno"> 416</span>  assign(swapa, va, otherVb);</div>
<div class="line"><a name="l00417"></a><span class="lineno"> 417</span> </div>
<div class="line"><a name="l00418"></a><span class="lineno"> 418</span>  <span class="comment">// kb is always second in the list, so we needn't use our lane</span></div>
<div class="line"><a name="l00419"></a><span class="lineno"> 419</span>  <span class="comment">// in this comparison</span></div>
<div class="line"><a name="l00420"></a><span class="lineno"> 420</span>  <span class="keywordflow">if</span> (FullMerge) {</div>
<div class="line"><a name="l00421"></a><span class="lineno"> 421</span>  <span class="keywordtype">bool</span> swapb = Dir ? Comp::lt(kb, otherKa) : Comp::gt(kb, otherKa);</div>
<div class="line"><a name="l00422"></a><span class="lineno"> 422</span>  assign(swapb, kb, otherKa);</div>
<div class="line"><a name="l00423"></a><span class="lineno"> 423</span>  assign(swapb, vb, otherVa);</div>
<div class="line"><a name="l00424"></a><span class="lineno"> 424</span> </div>
<div class="line"><a name="l00425"></a><span class="lineno"> 425</span>  } <span class="keywordflow">else</span> {</div>
<div class="line"><a name="l00426"></a><span class="lineno"> 426</span>  <span class="comment">// We don't care about updating elements in the second list</span></div>
<div class="line"><a name="l00427"></a><span class="lineno"> 427</span>  }</div>
<div class="line"><a name="l00428"></a><span class="lineno"> 428</span>  }</div>
<div class="line"><a name="l00429"></a><span class="lineno"> 429</span> </div>
<div class="line"><a name="l00430"></a><span class="lineno"> 430</span>  BitonicMergeStep<K, V, N1, Dir, Comp,</div>
<div class="line"><a name="l00431"></a><span class="lineno"> 431</span>  <span class="keyword">true</span>, utils::isPowerOf2(N1)>::merge(k1, v1);</div>
<div class="line"><a name="l00432"></a><span class="lineno"> 432</span>  <span class="keywordflow">if</span> (FullMerge) {</div>
<div class="line"><a name="l00433"></a><span class="lineno"> 433</span>  <span class="comment">// Only if we care about N2 do we need to bother merging it fully</span></div>
<div class="line"><a name="l00434"></a><span class="lineno"> 434</span>  BitonicMergeStep<K, V, N2, Dir, Comp,</div>
<div class="line"><a name="l00435"></a><span class="lineno"> 435</span>  <span class="keyword">false</span>, utils::isPowerOf2(N2)>::merge(k2, v2);</div>
<div class="line"><a name="l00436"></a><span class="lineno"> 436</span>  }</div>
<div class="line"><a name="l00437"></a><span class="lineno"> 437</span> }</div>
<div class="line"><a name="l00438"></a><span class="lineno"> 438</span> </div>
<div class="line"><a name="l00439"></a><span class="lineno"> 439</span> <span class="comment">// Recursive template that uses the above bitonic merge to perform a</span></div>
<div class="line"><a name="l00440"></a><span class="lineno"> 440</span> <span class="comment">// bitonic sort</span></div>
<div class="line"><a name="l00441"></a><span class="lineno"> 441</span> <span class="keyword">template</span> <<span class="keyword">typename</span> K, <span class="keyword">typename</span> V, <span class="keywordtype">int</span> N, <span class="keywordtype">bool</span> Dir, <span class="keyword">typename</span> Comp></div>
<div class="line"><a name="l00442"></a><span class="lineno"><a class="line" href="structfaiss_1_1gpu_1_1BitonicSortStep.html"> 442</a></span> <span class="keyword">struct </span><a class="code" href="structfaiss_1_1gpu_1_1BitonicSortStep.html">BitonicSortStep</a> {</div>
<div class="line"><a name="l00443"></a><span class="lineno"> 443</span>  <span class="keyword">static</span> <span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> sort(K k[N], V v[N]) {</div>
<div class="line"><a name="l00444"></a><span class="lineno"> 444</span>  static_assert(N > 1, <span class="stringliteral">"did not hit specialized case"</span>);</div>
<div class="line"><a name="l00445"></a><span class="lineno"> 445</span> </div>
<div class="line"><a name="l00446"></a><span class="lineno"> 446</span>  <span class="comment">// Sort recursively</span></div>
<div class="line"><a name="l00447"></a><span class="lineno"> 447</span>  constexpr <span class="keywordtype">int</span> kSizeA = N / 2;</div>
<div class="line"><a name="l00448"></a><span class="lineno"> 448</span>  constexpr <span class="keywordtype">int</span> kSizeB = N - kSizeA;</div>
<div class="line"><a name="l00449"></a><span class="lineno"> 449</span> </div>
<div class="line"><a name="l00450"></a><span class="lineno"> 450</span>  K aK[kSizeA];</div>
<div class="line"><a name="l00451"></a><span class="lineno"> 451</span>  V aV[kSizeA];</div>
<div class="line"><a name="l00452"></a><span class="lineno"> 452</span> </div>
<div class="line"><a name="l00453"></a><span class="lineno"> 453</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00454"></a><span class="lineno"> 454</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kSizeA; ++i) {</div>
<div class="line"><a name="l00455"></a><span class="lineno"> 455</span>  aK[i] = k[i];</div>
<div class="line"><a name="l00456"></a><span class="lineno"> 456</span>  aV[i] = v[i];</div>
<div class="line"><a name="l00457"></a><span class="lineno"> 457</span>  }</div>
<div class="line"><a name="l00458"></a><span class="lineno"> 458</span> </div>
<div class="line"><a name="l00459"></a><span class="lineno"> 459</span>  <a class="code" href="structfaiss_1_1gpu_1_1BitonicSortStep.html">BitonicSortStep<K, V, kSizeA, Dir, Comp>::sort</a>(aK, aV);</div>
<div class="line"><a name="l00460"></a><span class="lineno"> 460</span> </div>
<div class="line"><a name="l00461"></a><span class="lineno"> 461</span>  K bK[kSizeB];</div>
<div class="line"><a name="l00462"></a><span class="lineno"> 462</span>  V bV[kSizeB];</div>
<div class="line"><a name="l00463"></a><span class="lineno"> 463</span> </div>
<div class="line"><a name="l00464"></a><span class="lineno"> 464</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00465"></a><span class="lineno"> 465</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kSizeB; ++i) {</div>
<div class="line"><a name="l00466"></a><span class="lineno"> 466</span>  bK[i] = k[i + kSizeA];</div>
<div class="line"><a name="l00467"></a><span class="lineno"> 467</span>  bV[i] = v[i + kSizeA];</div>
<div class="line"><a name="l00468"></a><span class="lineno"> 468</span>  }</div>
<div class="line"><a name="l00469"></a><span class="lineno"> 469</span> </div>
<div class="line"><a name="l00470"></a><span class="lineno"> 470</span>  <a class="code" href="structfaiss_1_1gpu_1_1BitonicSortStep.html">BitonicSortStep<K, V, kSizeB, Dir, Comp>::sort</a>(bK, bV);</div>
<div class="line"><a name="l00471"></a><span class="lineno"> 471</span> </div>
<div class="line"><a name="l00472"></a><span class="lineno"> 472</span>  <span class="comment">// Merge halves</span></div>
<div class="line"><a name="l00473"></a><span class="lineno"> 473</span>  warpMergeAnyRegisters<K, V, kSizeA, kSizeB, Dir, Comp>(aK, aV, bK, bV);</div>
<div class="line"><a name="l00474"></a><span class="lineno"> 474</span> </div>
<div class="line"><a name="l00475"></a><span class="lineno"> 475</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00476"></a><span class="lineno"> 476</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kSizeA; ++i) {</div>
<div class="line"><a name="l00477"></a><span class="lineno"> 477</span>  k[i] = aK[i];</div>
<div class="line"><a name="l00478"></a><span class="lineno"> 478</span>  v[i] = aV[i];</div>
<div class="line"><a name="l00479"></a><span class="lineno"> 479</span>  }</div>
<div class="line"><a name="l00480"></a><span class="lineno"> 480</span> </div>
<div class="line"><a name="l00481"></a><span class="lineno"> 481</span> <span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00482"></a><span class="lineno"> 482</span> <span class="preprocessor"></span> <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i < kSizeB; ++i) {</div>
<div class="line"><a name="l00483"></a><span class="lineno"> 483</span>  k[i + kSizeA] = bK[i];</div>
<div class="line"><a name="l00484"></a><span class="lineno"> 484</span>  v[i + kSizeA] = bV[i];</div>
<div class="line"><a name="l00485"></a><span class="lineno"> 485</span>  }</div>
<div class="line"><a name="l00486"></a><span class="lineno"> 486</span>  }</div>
<div class="line"><a name="l00487"></a><span class="lineno"> 487</span> };</div>
<div class="line"><a name="l00488"></a><span class="lineno"> 488</span> </div>
<div class="line"><a name="l00489"></a><span class="lineno"> 489</span> <span class="comment">// Single warp (N == 1) sorting specialization</span></div>
<div class="line"><a name="l00490"></a><span class="lineno"> 490</span> <span class="keyword">template</span> <<span class="keyword">typename</span> K, <span class="keyword">typename</span> V, <span class="keywordtype">bool</span> Dir, <span class="keyword">typename</span> Comp></div>
<div class="line"><a name="l00491"></a><span class="lineno"><a class="line" href="structfaiss_1_1gpu_1_1BitonicSortStep_3_01K_00_01V_00_011_00_01Dir_00_01Comp_01_4.html"> 491</a></span> <span class="keyword">struct </span><a class="code" href="structfaiss_1_1gpu_1_1BitonicSortStep.html">BitonicSortStep</a><K, V, 1, Dir, Comp> {</div>
<div class="line"><a name="l00492"></a><span class="lineno"> 492</span>  <span class="keyword">static</span> <span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> sort(K k[1], V v[1]) {</div>
<div class="line"><a name="l00493"></a><span class="lineno"> 493</span>  <span class="comment">// Update this code if this changes</span></div>
<div class="line"><a name="l00494"></a><span class="lineno"> 494</span>  <span class="comment">// should go from 1 -> kWarpSize in multiples of 2</span></div>
<div class="line"><a name="l00495"></a><span class="lineno"> 495</span>  static_assert(kWarpSize == 32, <span class="stringliteral">"unexpected warp size"</span>);</div>
<div class="line"><a name="l00496"></a><span class="lineno"> 496</span> </div>
<div class="line"><a name="l00497"></a><span class="lineno"> 497</span>  warpBitonicMergeLE16<K, V, 1, Dir, Comp, false>(k[0], v[0]);</div>
<div class="line"><a name="l00498"></a><span class="lineno"> 498</span>  warpBitonicMergeLE16<K, V, 2, Dir, Comp, false>(k[0], v[0]);</div>
<div class="line"><a name="l00499"></a><span class="lineno"> 499</span>  warpBitonicMergeLE16<K, V, 4, Dir, Comp, false>(k[0], v[0]);</div>
<div class="line"><a name="l00500"></a><span class="lineno"> 500</span>  warpBitonicMergeLE16<K, V, 8, Dir, Comp, false>(k[0], v[0]);</div>
<div class="line"><a name="l00501"></a><span class="lineno"> 501</span>  warpBitonicMergeLE16<K, V, 16, Dir, Comp, false>(k[0], v[0]);</div>
<div class="line"><a name="l00502"></a><span class="lineno"> 502</span>  }</div>
<div class="line"><a name="l00503"></a><span class="lineno"> 503</span> };</div>
<div class="line"><a name="l00504"></a><span class="lineno"> 504</span> <span class="comment"></span></div>
<div class="line"><a name="l00505"></a><span class="lineno"> 505</span> <span class="comment">/// Sort a list of kWarpSize * N elements in registers, where N is an</span></div>
<div class="line"><a name="l00506"></a><span class="lineno"> 506</span> <span class="comment">/// arbitrary >= 1</span></div>
<div class="line"><a name="l00507"></a><span class="lineno"> 507</span> <span class="comment"></span><span class="keyword">template</span> <<span class="keyword">typename</span> K, <span class="keyword">typename</span> V, <span class="keywordtype">int</span> N, <span class="keywordtype">bool</span> Dir, <span class="keyword">typename</span> Comp></div>
<div class="line"><a name="l00508"></a><span class="lineno"> 508</span> <span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> warpSortAnyRegisters(K k[N], V v[N]) {</div>
<div class="line"><a name="l00509"></a><span class="lineno"> 509</span>  <a class="code" href="structfaiss_1_1gpu_1_1BitonicSortStep.html">BitonicSortStep<K, V, N, Dir, Comp>::sort</a>(k, v);</div>
<div class="line"><a name="l00510"></a><span class="lineno"> 510</span> }</div>
<div class="line"><a name="l00511"></a><span class="lineno"> 511</span> </div>
<div class="line"><a name="l00512"></a><span class="lineno"> 512</span> } } <span class="comment">// namespace</span></div>
<div class="ttc" id="structfaiss_1_1gpu_1_1BitonicSortStep_html"><div class="ttname"><a href="structfaiss_1_1gpu_1_1BitonicSortStep.html">faiss::gpu::BitonicSortStep</a></div><div class="ttdef"><b>Definition:</b> <a href="MergeNetworkWarp_8cuh_source.html#l00442">MergeNetworkWarp.cuh:442</a></div></div>
<div class="ttc" id="structfaiss_1_1gpu_1_1BitonicMergeStep_html"><div class="ttname"><a href="structfaiss_1_1gpu_1_1BitonicMergeStep.html">faiss::gpu::BitonicMergeStep</a></div><div class="ttdef"><b>Definition:</b> <a href="MergeNetworkWarp_8cuh_source.html#l00146">MergeNetworkWarp.cuh:146</a></div></div>
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