1 | //
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2 | // Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
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3 | //
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4 | // The contents of this file are covered under the licence agreement in the
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5 | // file "LICENCE" distributed with Cforall.
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6 | //
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7 | // Cost.h --
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8 | //
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9 | // Author : Peter Buhr and Aaron Moss
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10 | // Created On : Sun May 17 09:39:50 2015
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11 | // Last Modified By : Peter A. Buhr
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12 | // Last Modified On : Fri Jun 21 11:39:13 2019
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13 | // Update Count : 63
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14 | //
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15 |
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16 | #pragma once
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17 |
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18 | #include <iostream>
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19 | #include <cassert>
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20 | #include <climits>
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21 |
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22 | namespace ResolvExpr {
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23 | // To maximize performance and space, the 7 resolution costs are packed into a single 64-bit word. However, the
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24 | // specialization cost is a negative value so a correction is needed is a few places.
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25 |
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26 | class Cost {
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27 | union {
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28 | struct {
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29 | #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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30 | // Little-endian => first value is low priority and last is high priority.
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31 | unsigned char padding; ///< unused
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32 | unsigned char referenceCost; ///< reference conversions
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33 | unsigned char specCost; ///< Polymorphic type specializations (type assertions), negative cost
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34 | unsigned char varCost; ///< Count of polymorphic type variables
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35 | unsigned char signCost; ///< Count of safe sign conversions
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36 | unsigned char safeCost; ///< Safe (widening) conversions
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37 | unsigned char polyCost; ///< Count of parameters and return values bound to some poly type
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38 | unsigned char unsafeCost; ///< Unsafe (narrowing) conversions
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39 | #else
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40 | #error Cost BIG_ENDIAN unsupported
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41 | #endif
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42 | } v;
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43 | uint64_t all;
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44 | };
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45 | static const unsigned char correctb = 0xff; // byte correction for negative spec cost
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46 | static const uint64_t correctw = 0x00'00'00'00'00'ff'00'00; //' word correction for negative spec cost
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47 | public:
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48 | // Compiler adjusts constants for correct endian.
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49 | enum : uint64_t {
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50 | zero = 0x00'00'00'00'00'ff'00'00,
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51 | infinity = 0xff'ff'ff'ff'ff'00'ff'ff,
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52 | unsafe = 0x01'00'00'00'00'ff'00'00,
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53 | poly = 0x00'01'00'00'00'ff'00'00,
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54 | safe = 0x00'00'01'00'00'ff'00'00,
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55 | sign = 0x00'00'00'01'00'ff'00'00,
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56 | var = 0x00'00'00'00'01'ff'00'00,
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57 | spec = 0x00'00'00'00'00'fe'00'00,
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58 | reference = 0x00'00'00'00'00'ff'01'00,
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59 | }; //'
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60 |
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61 | Cost( uint64_t all ) { Cost::all = all; }
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62 | Cost( int unsafeCost, int polyCost, int safeCost, int signCost, int varCost, int specCost, int referenceCost ) {
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63 | // Assume little-endian => first value is low priority and last is high priority.
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64 | v = {
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65 | #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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66 | (unsigned char)0, // padding
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67 | (unsigned char)referenceCost, // low priority
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68 | (unsigned char)(specCost + correctb), // correct for signedness
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69 | (unsigned char)varCost,
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70 | (unsigned char)signCost,
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71 | (unsigned char)safeCost,
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72 | (unsigned char)polyCost,
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73 | (unsigned char)unsafeCost, // high priority
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74 | #else
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75 | #error Cost BIG_ENDIAN unsupported
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76 | #endif
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77 | };
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78 | }
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79 |
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80 | int get_unsafeCost() const { return v.unsafeCost; }
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81 | int get_polyCost() const { return v.polyCost; }
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82 | int get_safeCost() const { return v.safeCost; }
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83 | int get_signCost() const { return v.signCost; }
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84 | int get_varCost() const { return v.varCost; }
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85 | int get_specCost() const { return -(correctb - v.specCost); }
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86 | int get_referenceCost() const { return v.referenceCost; }
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87 |
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88 | friend bool operator==( const Cost, const Cost );
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89 | friend bool operator!=( const Cost lhs, const Cost rhs );
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90 | // returns negative for *this < rhs, 0 for *this == rhs, positive for *this > rhs
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91 | int compare( const Cost rhs ) const {
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92 | if ( all == infinity ) return 1;
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93 | if ( rhs.all == infinity ) return -1;
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94 | return all > rhs.all ? 1 : all == rhs.all ? 0 : -1;
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95 | }
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96 | friend bool operator<( const Cost lhs, const Cost rhs );
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97 |
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98 | friend Cost operator+( const Cost lhs, const Cost rhs );
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99 |
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100 | Cost operator+=( const Cost rhs ) {
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101 | if ( all == infinity ) return *this;
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102 | if ( rhs.all == infinity ) {
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103 | all = infinity;
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104 | return *this;
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105 | }
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106 | all += rhs.all - correctw; // correct for negative spec cost
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107 | return *this;
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108 | }
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109 |
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110 | Cost incUnsafe( int inc = 1 ) {
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111 | if ( all != infinity ) { assert( v.unsafeCost + inc <= UCHAR_MAX ); v.unsafeCost += inc; }
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112 | return *this;
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113 | }
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114 |
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115 | Cost incPoly( int inc = 1 ) {
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116 | if ( all != infinity ) { assert( v.polyCost + inc <= UCHAR_MAX ); v.polyCost += inc; }
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117 | return *this;
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118 | }
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119 |
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120 | Cost incSafe( int inc = 1 ) {
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121 | if ( all != infinity ) { assert( v.safeCost + inc <= UCHAR_MAX ); v.safeCost += inc; }
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122 | return *this;
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123 | }
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124 |
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125 | Cost incSign( int inc = 1 ) {
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126 | if ( all != infinity ) { assert( v.signCost + inc <= UCHAR_MAX ); v.signCost += inc; }
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127 | return *this;
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128 | }
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129 |
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130 | Cost incVar( int inc = 1 ) {
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131 | if ( all != infinity ) { assert( v.varCost + inc <= UCHAR_MAX ); v.varCost += inc; }
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132 | return *this;
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133 | }
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134 |
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135 | Cost decSpec( int dec = 1 ) {
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136 | if ( all != infinity ) { assert( v.specCost - dec >= 0 ); v.specCost -= dec; }
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137 | return *this;
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138 | }
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139 |
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140 | Cost incReference( int inc = 1 ) {
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141 | if ( all != infinity ) { assert( v.referenceCost + inc <= UCHAR_MAX ); v.referenceCost += inc; }
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142 | return *this;
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143 | }
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144 |
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145 | friend std::ostream & operator<<( std::ostream & os, const Cost cost );
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146 | };
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147 |
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148 | inline bool operator==( const Cost lhs, const Cost rhs ) {
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149 | return lhs.all == rhs.all;
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150 | }
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151 |
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152 | inline bool operator!=( const Cost lhs, const Cost rhs ) {
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153 | return !( lhs.all == rhs.all );
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154 | }
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155 |
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156 | inline bool operator<( const Cost lhs, const Cost rhs ) {
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157 | if ( lhs.all == Cost::infinity ) return false;
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158 | if ( rhs.all == Cost::infinity ) return true;
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159 | return lhs.all < rhs.all;
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160 | }
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161 |
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162 | inline Cost operator+( const Cost lhs, const Cost rhs ) {
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163 | if ( lhs.all == Cost::infinity || rhs.all == Cost::infinity ) return Cost{ Cost::infinity };
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164 | return Cost{ lhs.all + rhs.all - Cost::correctw }; // correct for negative spec cost
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165 | }
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166 |
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167 | inline std::ostream & operator<<( std::ostream & os, const Cost cost ) {
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168 | return os << "( " << cost.get_unsafeCost() << ", " << cost.get_polyCost() << ", " << cost.get_safeCost()
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169 | << ", " << cost.get_signCost() << ", " << cost.get_varCost() << ", " << cost.get_specCost()
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170 | << ", " << cost.get_referenceCost() << " )";
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171 | }
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172 | } // namespace ResolvExpr
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173 |
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174 | // Local Variables: //
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175 | // tab-width: 4 //
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176 | // mode: c++ //
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177 | // compile-command: "make install" //
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178 | // End: //
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