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 | // CandidateFinder.cpp -- |
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8 | // |
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9 | // Author : Aaron B. Moss |
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10 | // Created On : Wed Jun 5 14:30:00 2019 |
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11 | // Last Modified By : Andrew Beach |
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12 | // Last Modified On : Tue Oct 1 14:55:00 2019 |
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13 | // Update Count : 2 |
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14 | // |
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15 | |
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16 | #include "CandidateFinder.hpp" |
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17 | |
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18 | #include <deque> |
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19 | #include <iterator> // for back_inserter |
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20 | #include <sstream> |
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21 | #include <string> |
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22 | #include <unordered_map> |
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23 | #include <vector> |
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24 | |
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25 | #include "Candidate.hpp" |
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26 | #include "CompilationState.h" |
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27 | #include "Cost.h" |
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28 | #include "ExplodedArg.hpp" |
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29 | #include "RenameVars.h" // for renameTyVars |
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30 | #include "Resolver.h" |
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31 | #include "ResolveTypeof.h" |
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32 | #include "SatisfyAssertions.hpp" |
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33 | #include "typeops.h" // for adjustExprType, conversionCost, polyCost, specCost |
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34 | #include "Unify.h" |
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35 | #include "AST/Expr.hpp" |
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36 | #include "AST/Node.hpp" |
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37 | #include "AST/Pass.hpp" |
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38 | #include "AST/Print.hpp" |
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39 | #include "AST/SymbolTable.hpp" |
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40 | #include "AST/Type.hpp" |
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41 | #include "Common/utility.h" // for move, copy |
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42 | #include "SymTab/Mangler.h" |
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43 | #include "SymTab/Validate.h" // for validateType |
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44 | #include "Tuples/Tuples.h" // for handleTupleAssignment |
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45 | |
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46 | #define PRINT( text ) if ( resolvep ) { text } |
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47 | |
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48 | namespace ResolvExpr { |
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49 | |
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50 | const ast::Expr * referenceToRvalueConversion( const ast::Expr * expr, Cost & cost ) { |
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51 | if ( expr->result.as< ast::ReferenceType >() ) { |
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52 | // cast away reference from expr |
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53 | cost.incReference(); |
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54 | return new ast::CastExpr{ expr, expr->result->stripReferences() }; |
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55 | } |
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56 | |
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57 | return expr; |
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58 | } |
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59 | |
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60 | /// Unique identifier for matching expression resolutions to their requesting expression |
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61 | UniqueId globalResnSlot = 0; |
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62 | |
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63 | Cost computeConversionCost( |
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64 | const ast::Type * argType, const ast::Type * paramType, bool argIsLvalue, |
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65 | const ast::SymbolTable & symtab, const ast::TypeEnvironment & env |
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66 | ) { |
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67 | PRINT( |
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68 | std::cerr << std::endl << "converting "; |
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69 | ast::print( std::cerr, argType, 2 ); |
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70 | std::cerr << std::endl << " to "; |
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71 | ast::print( std::cerr, paramType, 2 ); |
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72 | std::cerr << std::endl << "environment is: "; |
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73 | ast::print( std::cerr, env, 2 ); |
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74 | std::cerr << std::endl; |
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75 | ) |
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76 | Cost convCost = conversionCost( argType, paramType, argIsLvalue, symtab, env ); |
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77 | PRINT( |
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78 | std::cerr << std::endl << "cost is " << convCost << std::endl; |
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79 | ) |
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80 | if ( convCost == Cost::infinity ) return convCost; |
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81 | convCost.incPoly( polyCost( paramType, symtab, env ) + polyCost( argType, symtab, env ) ); |
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82 | PRINT( |
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83 | std::cerr << "cost with polycost is " << convCost << std::endl; |
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84 | ) |
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85 | return convCost; |
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86 | } |
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87 | |
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88 | namespace { |
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89 | /// First index is which argument, second is which alternative, third is which exploded element |
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90 | using ExplodedArgs_new = std::deque< std::vector< ExplodedArg > >; |
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91 | |
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92 | /// Returns a list of alternatives with the minimum cost in the given list |
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93 | CandidateList findMinCost( const CandidateList & candidates ) { |
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94 | CandidateList out; |
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95 | Cost minCost = Cost::infinity; |
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96 | for ( const CandidateRef & r : candidates ) { |
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97 | if ( r->cost < minCost ) { |
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98 | minCost = r->cost; |
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99 | out.clear(); |
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100 | out.emplace_back( r ); |
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101 | } else if ( r->cost == minCost ) { |
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102 | out.emplace_back( r ); |
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103 | } |
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104 | } |
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105 | return out; |
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106 | } |
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107 | |
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108 | /// Computes conversion cost for a given expression to a given type |
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109 | const ast::Expr * computeExpressionConversionCost( |
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110 | const ast::Expr * arg, const ast::Type * paramType, const ast::SymbolTable & symtab, const ast::TypeEnvironment & env, Cost & outCost |
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111 | ) { |
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112 | Cost convCost = computeConversionCost( |
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113 | arg->result, paramType, arg->get_lvalue(), symtab, env ); |
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114 | outCost += convCost; |
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115 | |
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116 | // If there is a non-zero conversion cost, ignoring poly cost, then the expression requires |
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117 | // conversion. Ignore poly cost for now, since this requires resolution of the cast to |
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118 | // infer parameters and this does not currently work for the reason stated below |
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119 | Cost tmpCost = convCost; |
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120 | tmpCost.incPoly( -tmpCost.get_polyCost() ); |
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121 | if ( tmpCost != Cost::zero ) { |
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122 | ast::ptr< ast::Type > newType = paramType; |
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123 | env.apply( newType ); |
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124 | return new ast::CastExpr{ arg, newType }; |
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125 | |
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126 | // xxx - *should* be able to resolve this cast, but at the moment pointers are not |
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127 | // castable to zero_t, but are implicitly convertible. This is clearly inconsistent, |
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128 | // once this is fixed it should be possible to resolve the cast. |
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129 | // xxx - this isn't working, it appears because type1 (parameter) is seen as widenable, |
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130 | // but it shouldn't be because this makes the conversion from DT* to DT* since |
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131 | // commontype(zero_t, DT*) is DT*, rather than nothing |
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132 | |
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133 | // CandidateFinder finder{ symtab, env }; |
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134 | // finder.find( arg, ResolvMode::withAdjustment() ); |
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135 | // assertf( finder.candidates.size() > 0, |
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136 | // "Somehow castable expression failed to find alternatives." ); |
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137 | // assertf( finder.candidates.size() == 1, |
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138 | // "Somehow got multiple alternatives for known cast expression." ); |
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139 | // return finder.candidates.front()->expr; |
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140 | } |
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141 | |
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142 | return arg; |
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143 | } |
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144 | |
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145 | /// Computes conversion cost for a given candidate |
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146 | Cost computeApplicationConversionCost( |
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147 | CandidateRef cand, const ast::SymbolTable & symtab |
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148 | ) { |
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149 | auto appExpr = cand->expr.strict_as< ast::ApplicationExpr >(); |
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150 | auto pointer = appExpr->func->result.strict_as< ast::PointerType >(); |
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151 | auto function = pointer->base.strict_as< ast::FunctionType >(); |
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152 | |
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153 | Cost convCost = Cost::zero; |
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154 | const auto & params = function->params; |
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155 | auto param = params.begin(); |
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156 | auto & args = appExpr->args; |
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157 | |
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158 | for ( unsigned i = 0; i < args.size(); ++i ) { |
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159 | const ast::Type * argType = args[i]->result; |
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160 | PRINT( |
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161 | std::cerr << "arg expression:" << std::endl; |
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162 | ast::print( std::cerr, args[i], 2 ); |
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163 | std::cerr << "--- results are" << std::endl; |
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164 | ast::print( std::cerr, argType, 2 ); |
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165 | ) |
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166 | |
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167 | if ( param == params.end() ) { |
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168 | if ( function->isVarArgs ) { |
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169 | convCost.incUnsafe(); |
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170 | PRINT( std::cerr << "end of params with varargs function: inc unsafe: " |
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171 | << convCost << std::endl; ; ) |
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172 | // convert reference-typed expressions into value-typed expressions |
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173 | cand->expr = ast::mutate_field_index( |
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174 | appExpr, &ast::ApplicationExpr::args, i, |
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175 | referenceToRvalueConversion( args[i], convCost ) ); |
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176 | continue; |
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177 | } else return Cost::infinity; |
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178 | } |
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179 | |
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180 | if ( auto def = args[i].as< ast::DefaultArgExpr >() ) { |
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181 | // Default arguments should be free - don't include conversion cost. |
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182 | // Unwrap them here because they are not relevant to the rest of the system |
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183 | cand->expr = ast::mutate_field_index( |
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184 | appExpr, &ast::ApplicationExpr::args, i, def->expr ); |
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185 | ++param; |
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186 | continue; |
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187 | } |
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188 | |
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189 | // mark conversion cost and also specialization cost of param type |
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190 | const ast::Type * paramType = (*param)->get_type(); |
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191 | cand->expr = ast::mutate_field_index( |
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192 | appExpr, &ast::ApplicationExpr::args, i, |
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193 | computeExpressionConversionCost( |
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194 | args[i], paramType, symtab, cand->env, convCost ) ); |
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195 | convCost.decSpec( specCost( paramType ) ); |
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196 | ++param; // can't be in for-loop update because of the continue |
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197 | } |
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198 | |
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199 | if ( param != params.end() ) return Cost::infinity; |
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200 | |
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201 | // specialization cost of return types can't be accounted for directly, it disables |
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202 | // otherwise-identical calls, like this example based on auto-newline in the I/O lib: |
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203 | // |
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204 | // forall(otype OS) { |
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205 | // void ?|?(OS&, int); // with newline |
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206 | // OS& ?|?(OS&, int); // no newline, always chosen due to more specialization |
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207 | // } |
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208 | |
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209 | // mark type variable and specialization cost of forall clause |
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210 | convCost.incVar( function->forall.size() ); |
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211 | for ( const ast::TypeDecl * td : function->forall ) { |
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212 | convCost.decSpec( td->assertions.size() ); |
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213 | } |
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214 | |
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215 | return convCost; |
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216 | } |
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217 | |
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218 | void makeUnifiableVars( |
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219 | const ast::ParameterizedType * type, ast::OpenVarSet & unifiableVars, |
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220 | ast::AssertionSet & need |
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221 | ) { |
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222 | for ( const ast::TypeDecl * tyvar : type->forall ) { |
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223 | unifiableVars[ tyvar->name ] = ast::TypeDecl::Data{ tyvar }; |
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224 | for ( const ast::DeclWithType * assn : tyvar->assertions ) { |
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225 | need[ assn ].isUsed = true; |
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226 | } |
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227 | } |
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228 | } |
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229 | |
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230 | /// Gets a default value from an initializer, nullptr if not present |
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231 | const ast::ConstantExpr * getDefaultValue( const ast::Init * init ) { |
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232 | if ( auto si = dynamic_cast< const ast::SingleInit * >( init ) ) { |
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233 | if ( auto ce = si->value.as< ast::CastExpr >() ) { |
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234 | return ce->arg.as< ast::ConstantExpr >(); |
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235 | } else { |
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236 | return si->value.as< ast::ConstantExpr >(); |
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237 | } |
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238 | } |
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239 | return nullptr; |
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240 | } |
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241 | |
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242 | /// State to iteratively build a match of parameter expressions to arguments |
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243 | struct ArgPack { |
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244 | std::size_t parent; ///< Index of parent pack |
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245 | ast::ptr< ast::Expr > expr; ///< The argument stored here |
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246 | Cost cost; ///< The cost of this argument |
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247 | ast::TypeEnvironment env; ///< Environment for this pack |
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248 | ast::AssertionSet need; ///< Assertions outstanding for this pack |
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249 | ast::AssertionSet have; ///< Assertions found for this pack |
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250 | ast::OpenVarSet open; ///< Open variables for this pack |
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251 | unsigned nextArg; ///< Index of next argument in arguments list |
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252 | unsigned tupleStart; ///< Number of tuples that start at this index |
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253 | unsigned nextExpl; ///< Index of next exploded element |
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254 | unsigned explAlt; ///< Index of alternative for nextExpl > 0 |
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255 | |
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256 | ArgPack() |
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257 | : parent( 0 ), expr(), cost( Cost::zero ), env(), need(), have(), open(), nextArg( 0 ), |
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258 | tupleStart( 0 ), nextExpl( 0 ), explAlt( 0 ) {} |
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259 | |
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260 | ArgPack( |
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261 | const ast::TypeEnvironment & env, const ast::AssertionSet & need, |
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262 | const ast::AssertionSet & have, const ast::OpenVarSet & open ) |
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263 | : parent( 0 ), expr(), cost( Cost::zero ), env( env ), need( need ), have( have ), |
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264 | open( open ), nextArg( 0 ), tupleStart( 0 ), nextExpl( 0 ), explAlt( 0 ) {} |
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265 | |
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266 | ArgPack( |
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267 | std::size_t parent, const ast::Expr * expr, ast::TypeEnvironment && env, |
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268 | ast::AssertionSet && need, ast::AssertionSet && have, ast::OpenVarSet && open, |
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269 | unsigned nextArg, unsigned tupleStart = 0, Cost cost = Cost::zero, |
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270 | unsigned nextExpl = 0, unsigned explAlt = 0 ) |
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271 | : parent(parent), expr( expr ), cost( cost ), env( move( env ) ), need( move( need ) ), |
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272 | have( move( have ) ), open( move( open ) ), nextArg( nextArg ), tupleStart( tupleStart ), |
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273 | nextExpl( nextExpl ), explAlt( explAlt ) {} |
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274 | |
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275 | ArgPack( |
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276 | const ArgPack & o, ast::TypeEnvironment && env, ast::AssertionSet && need, |
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277 | ast::AssertionSet && have, ast::OpenVarSet && open, unsigned nextArg, Cost added ) |
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278 | : parent( o.parent ), expr( o.expr ), cost( o.cost + added ), env( move( env ) ), |
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279 | need( move( need ) ), have( move( have ) ), open( move( open ) ), nextArg( nextArg ), |
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280 | tupleStart( o.tupleStart ), nextExpl( 0 ), explAlt( 0 ) {} |
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281 | |
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282 | /// true if this pack is in the middle of an exploded argument |
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283 | bool hasExpl() const { return nextExpl > 0; } |
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284 | |
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285 | /// Gets the list of exploded candidates for this pack |
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286 | const ExplodedArg & getExpl( const ExplodedArgs_new & args ) const { |
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287 | return args[ nextArg-1 ][ explAlt ]; |
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288 | } |
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289 | |
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290 | /// Ends a tuple expression, consolidating the appropriate args |
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291 | void endTuple( const std::vector< ArgPack > & packs ) { |
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292 | // add all expressions in tuple to list, summing cost |
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293 | std::deque< const ast::Expr * > exprs; |
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294 | const ArgPack * pack = this; |
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295 | if ( expr ) { exprs.emplace_front( expr ); } |
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296 | while ( pack->tupleStart == 0 ) { |
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297 | pack = &packs[pack->parent]; |
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298 | exprs.emplace_front( pack->expr ); |
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299 | cost += pack->cost; |
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300 | } |
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301 | // reset pack to appropriate tuple |
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302 | std::vector< ast::ptr< ast::Expr > > exprv( exprs.begin(), exprs.end() ); |
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303 | expr = new ast::TupleExpr{ expr->location, move( exprv ) }; |
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304 | tupleStart = pack->tupleStart - 1; |
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305 | parent = pack->parent; |
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306 | } |
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307 | }; |
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308 | |
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309 | /// Instantiates an argument to match a parameter, returns false if no matching results left |
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310 | bool instantiateArgument( |
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311 | const ast::Type * paramType, const ast::Init * init, const ExplodedArgs_new & args, |
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312 | std::vector< ArgPack > & results, std::size_t & genStart, const ast::SymbolTable & symtab, |
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313 | unsigned nTuples = 0 |
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314 | ) { |
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315 | if ( auto tupleType = dynamic_cast< const ast::TupleType * >( paramType ) ) { |
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316 | // paramType is a TupleType -- group args into a TupleExpr |
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317 | ++nTuples; |
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318 | for ( const ast::Type * type : *tupleType ) { |
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319 | // xxx - dropping initializer changes behaviour from previous, but seems correct |
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320 | // ^^^ need to handle the case where a tuple has a default argument |
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321 | if ( ! instantiateArgument( |
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322 | type, nullptr, args, results, genStart, symtab, nTuples ) ) return false; |
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323 | nTuples = 0; |
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324 | } |
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325 | // re-constitute tuples for final generation |
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326 | for ( auto i = genStart; i < results.size(); ++i ) { |
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327 | results[i].endTuple( results ); |
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328 | } |
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329 | return true; |
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330 | } else if ( const ast::TypeInstType * ttype = Tuples::isTtype( paramType ) ) { |
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331 | // paramType is a ttype, consumes all remaining arguments |
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332 | |
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333 | // completed tuples; will be spliced to end of results to finish |
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334 | std::vector< ArgPack > finalResults{}; |
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335 | |
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336 | // iterate until all results completed |
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337 | std::size_t genEnd; |
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338 | ++nTuples; |
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339 | do { |
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340 | genEnd = results.size(); |
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341 | |
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342 | // add another argument to results |
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343 | for ( std::size_t i = genStart; i < genEnd; ++i ) { |
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344 | unsigned nextArg = results[i].nextArg; |
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345 | |
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346 | // use next element of exploded tuple if present |
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347 | if ( results[i].hasExpl() ) { |
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348 | const ExplodedArg & expl = results[i].getExpl( args ); |
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349 | |
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350 | unsigned nextExpl = results[i].nextExpl + 1; |
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351 | if ( nextExpl == expl.exprs.size() ) { nextExpl = 0; } |
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352 | |
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353 | results.emplace_back( |
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354 | i, expl.exprs[ results[i].nextExpl ], copy( results[i].env ), |
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355 | copy( results[i].need ), copy( results[i].have ), |
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356 | copy( results[i].open ), nextArg, nTuples, Cost::zero, nextExpl, |
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357 | results[i].explAlt ); |
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358 | |
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359 | continue; |
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360 | } |
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361 | |
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362 | // finish result when out of arguments |
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363 | if ( nextArg >= args.size() ) { |
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364 | ArgPack newResult{ |
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365 | results[i].env, results[i].need, results[i].have, results[i].open }; |
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366 | newResult.nextArg = nextArg; |
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367 | const ast::Type * argType = nullptr; |
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368 | |
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369 | if ( nTuples > 0 || ! results[i].expr ) { |
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370 | // first iteration or no expression to clone, |
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371 | // push empty tuple expression |
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372 | newResult.parent = i; |
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373 | newResult.expr = new ast::TupleExpr{ CodeLocation{}, {} }; |
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374 | argType = newResult.expr->result; |
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375 | } else { |
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376 | // clone result to collect tuple |
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377 | newResult.parent = results[i].parent; |
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378 | newResult.cost = results[i].cost; |
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379 | newResult.tupleStart = results[i].tupleStart; |
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380 | newResult.expr = results[i].expr; |
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381 | argType = newResult.expr->result; |
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382 | |
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383 | if ( results[i].tupleStart > 0 && Tuples::isTtype( argType ) ) { |
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384 | // the case where a ttype value is passed directly is special, |
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385 | // e.g. for argument forwarding purposes |
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386 | // xxx - what if passing multiple arguments, last of which is |
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387 | // ttype? |
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388 | // xxx - what would happen if unify was changed so that unifying |
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389 | // tuple |
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390 | // types flattened both before unifying lists? then pass in |
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391 | // TupleType (ttype) below. |
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392 | --newResult.tupleStart; |
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393 | } else { |
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394 | // collapse leftover arguments into tuple |
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395 | newResult.endTuple( results ); |
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396 | argType = newResult.expr->result; |
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397 | } |
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398 | } |
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399 | |
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400 | // check unification for ttype before adding to final |
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401 | if ( |
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402 | unify( |
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403 | ttype, argType, newResult.env, newResult.need, newResult.have, |
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404 | newResult.open, symtab ) |
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405 | ) { |
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406 | finalResults.emplace_back( move( newResult ) ); |
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407 | } |
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408 | |
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409 | continue; |
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410 | } |
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411 | |
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412 | // add each possible next argument |
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413 | for ( std::size_t j = 0; j < args[nextArg].size(); ++j ) { |
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414 | const ExplodedArg & expl = args[nextArg][j]; |
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415 | |
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416 | // fresh copies of parent parameters for this iteration |
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417 | ast::TypeEnvironment env = results[i].env; |
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418 | ast::OpenVarSet open = results[i].open; |
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419 | |
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420 | env.addActual( expl.env, open ); |
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421 | |
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422 | // skip empty tuple arguments by (nearly) cloning parent into next gen |
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423 | if ( expl.exprs.empty() ) { |
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424 | results.emplace_back( |
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425 | results[i], move( env ), copy( results[i].need ), |
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426 | copy( results[i].have ), move( open ), nextArg + 1, expl.cost ); |
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427 | |
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428 | continue; |
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429 | } |
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430 | |
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431 | // add new result |
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432 | results.emplace_back( |
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433 | i, expl.exprs.front(), move( env ), copy( results[i].need ), |
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434 | copy( results[i].have ), move( open ), nextArg + 1, nTuples, |
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435 | expl.cost, expl.exprs.size() == 1 ? 0 : 1, j ); |
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436 | } |
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437 | } |
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438 | |
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439 | // reset for next round |
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440 | genStart = genEnd; |
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441 | nTuples = 0; |
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442 | } while ( genEnd != results.size() ); |
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443 | |
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444 | // splice final results onto results |
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445 | for ( std::size_t i = 0; i < finalResults.size(); ++i ) { |
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446 | results.emplace_back( move( finalResults[i] ) ); |
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447 | } |
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448 | return ! finalResults.empty(); |
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449 | } |
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450 | |
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451 | // iterate each current subresult |
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452 | std::size_t genEnd = results.size(); |
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453 | for ( std::size_t i = genStart; i < genEnd; ++i ) { |
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454 | unsigned nextArg = results[i].nextArg; |
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455 | |
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456 | // use remainder of exploded tuple if present |
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457 | if ( results[i].hasExpl() ) { |
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458 | const ExplodedArg & expl = results[i].getExpl( args ); |
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459 | const ast::Expr * expr = expl.exprs[ results[i].nextExpl ]; |
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460 | |
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461 | ast::TypeEnvironment env = results[i].env; |
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462 | ast::AssertionSet need = results[i].need, have = results[i].have; |
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463 | ast::OpenVarSet open = results[i].open; |
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464 | |
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465 | const ast::Type * argType = expr->result; |
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466 | |
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467 | PRINT( |
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468 | std::cerr << "param type is "; |
---|
469 | ast::print( std::cerr, paramType ); |
---|
470 | std::cerr << std::endl << "arg type is "; |
---|
471 | ast::print( std::cerr, argType ); |
---|
472 | std::cerr << std::endl; |
---|
473 | ) |
---|
474 | |
---|
475 | if ( unify( paramType, argType, env, need, have, open, symtab ) ) { |
---|
476 | unsigned nextExpl = results[i].nextExpl + 1; |
---|
477 | if ( nextExpl == expl.exprs.size() ) { nextExpl = 0; } |
---|
478 | |
---|
479 | results.emplace_back( |
---|
480 | i, expr, move( env ), move( need ), move( have ), move( open ), nextArg, |
---|
481 | nTuples, Cost::zero, nextExpl, results[i].explAlt ); |
---|
482 | } |
---|
483 | |
---|
484 | continue; |
---|
485 | } |
---|
486 | |
---|
487 | // use default initializers if out of arguments |
---|
488 | if ( nextArg >= args.size() ) { |
---|
489 | if ( const ast::ConstantExpr * cnst = getDefaultValue( init ) ) { |
---|
490 | ast::TypeEnvironment env = results[i].env; |
---|
491 | ast::AssertionSet need = results[i].need, have = results[i].have; |
---|
492 | ast::OpenVarSet open = results[i].open; |
---|
493 | |
---|
494 | if ( unify( paramType, cnst->result, env, need, have, open, symtab ) ) { |
---|
495 | results.emplace_back( |
---|
496 | i, new ast::DefaultArgExpr{ cnst->location, cnst }, move( env ), |
---|
497 | move( need ), move( have ), move( open ), nextArg, nTuples ); |
---|
498 | } |
---|
499 | } |
---|
500 | |
---|
501 | continue; |
---|
502 | } |
---|
503 | |
---|
504 | // Check each possible next argument |
---|
505 | for ( std::size_t j = 0; j < args[nextArg].size(); ++j ) { |
---|
506 | const ExplodedArg & expl = args[nextArg][j]; |
---|
507 | |
---|
508 | // fresh copies of parent parameters for this iteration |
---|
509 | ast::TypeEnvironment env = results[i].env; |
---|
510 | ast::AssertionSet need = results[i].need, have = results[i].have; |
---|
511 | ast::OpenVarSet open = results[i].open; |
---|
512 | |
---|
513 | env.addActual( expl.env, open ); |
---|
514 | |
---|
515 | // skip empty tuple arguments by (nearly) cloning parent into next gen |
---|
516 | if ( expl.exprs.empty() ) { |
---|
517 | results.emplace_back( |
---|
518 | results[i], move( env ), move( need ), move( have ), move( open ), |
---|
519 | nextArg + 1, expl.cost ); |
---|
520 | |
---|
521 | continue; |
---|
522 | } |
---|
523 | |
---|
524 | // consider only first exploded arg |
---|
525 | const ast::Expr * expr = expl.exprs.front(); |
---|
526 | const ast::Type * argType = expr->result; |
---|
527 | |
---|
528 | PRINT( |
---|
529 | std::cerr << "param type is "; |
---|
530 | ast::print( std::cerr, paramType ); |
---|
531 | std::cerr << std::endl << "arg type is "; |
---|
532 | ast::print( std::cerr, argType ); |
---|
533 | std::cerr << std::endl; |
---|
534 | ) |
---|
535 | |
---|
536 | // attempt to unify types |
---|
537 | if ( unify( paramType, argType, env, need, have, open, symtab ) ) { |
---|
538 | // add new result |
---|
539 | results.emplace_back( |
---|
540 | i, expr, move( env ), move( need ), move( have ), move( open ), |
---|
541 | nextArg + 1, nTuples, expl.cost, expl.exprs.size() == 1 ? 0 : 1, j ); |
---|
542 | } |
---|
543 | } |
---|
544 | } |
---|
545 | |
---|
546 | // reset for next parameter |
---|
547 | genStart = genEnd; |
---|
548 | |
---|
549 | return genEnd != results.size(); // were any new results added? |
---|
550 | } |
---|
551 | |
---|
552 | /// Generate a cast expression from `arg` to `toType` |
---|
553 | const ast::Expr * restructureCast( |
---|
554 | ast::ptr< ast::Expr > & arg, const ast::Type * toType, ast::GeneratedFlag isGenerated = ast::GeneratedCast |
---|
555 | ) { |
---|
556 | if ( |
---|
557 | arg->result->size() > 1 |
---|
558 | && ! toType->isVoid() |
---|
559 | && ! dynamic_cast< const ast::ReferenceType * >( toType ) |
---|
560 | ) { |
---|
561 | // Argument is a tuple and the target type is neither void nor a reference. Cast each |
---|
562 | // member of the tuple to its corresponding target type, producing the tuple of those |
---|
563 | // cast expressions. If there are more components of the tuple than components in the |
---|
564 | // target type, then excess components do not come out in the result expression (but |
---|
565 | // UniqueExpr ensures that the side effects will still be produced) |
---|
566 | if ( Tuples::maybeImpureIgnoreUnique( arg ) ) { |
---|
567 | // expressions which may contain side effects require a single unique instance of |
---|
568 | // the expression |
---|
569 | arg = new ast::UniqueExpr{ arg->location, arg }; |
---|
570 | } |
---|
571 | std::vector< ast::ptr< ast::Expr > > components; |
---|
572 | for ( unsigned i = 0; i < toType->size(); ++i ) { |
---|
573 | // cast each component |
---|
574 | ast::ptr< ast::Expr > idx = new ast::TupleIndexExpr{ arg->location, arg, i }; |
---|
575 | components.emplace_back( |
---|
576 | restructureCast( idx, toType->getComponent( i ), isGenerated ) ); |
---|
577 | } |
---|
578 | return new ast::TupleExpr{ arg->location, move( components ) }; |
---|
579 | } else { |
---|
580 | // handle normally |
---|
581 | return new ast::CastExpr{ arg->location, arg, toType, isGenerated }; |
---|
582 | } |
---|
583 | } |
---|
584 | |
---|
585 | /// Gets the name from an untyped member expression (must be NameExpr) |
---|
586 | const std::string & getMemberName( const ast::UntypedMemberExpr * memberExpr ) { |
---|
587 | if ( memberExpr->member.as< ast::ConstantExpr >() ) { |
---|
588 | SemanticError( memberExpr, "Indexed access to struct fields unsupported: " ); |
---|
589 | } |
---|
590 | |
---|
591 | return memberExpr->member.strict_as< ast::NameExpr >()->name; |
---|
592 | } |
---|
593 | |
---|
594 | /// Actually visits expressions to find their candidate interpretations |
---|
595 | class Finder final : public ast::WithShortCircuiting { |
---|
596 | const ast::SymbolTable & symtab; |
---|
597 | public: |
---|
598 | CandidateFinder & selfFinder; |
---|
599 | CandidateList & candidates; |
---|
600 | const ast::TypeEnvironment & tenv; |
---|
601 | ast::ptr< ast::Type > & targetType; |
---|
602 | |
---|
603 | enum Errors { |
---|
604 | NotFound, |
---|
605 | NoMatch, |
---|
606 | ArgsToFew, |
---|
607 | ArgsToMany, |
---|
608 | RetsToFew, |
---|
609 | RetsToMany, |
---|
610 | NoReason |
---|
611 | }; |
---|
612 | |
---|
613 | struct { |
---|
614 | Errors code = NotFound; |
---|
615 | } reason; |
---|
616 | |
---|
617 | Finder( CandidateFinder & f ) |
---|
618 | : symtab( f.localSyms ), selfFinder( f ), candidates( f.candidates ), tenv( f.env ), |
---|
619 | targetType( f.targetType ) {} |
---|
620 | |
---|
621 | void previsit( const ast::Node * ) { visit_children = false; } |
---|
622 | |
---|
623 | /// Convenience to add candidate to list |
---|
624 | template<typename... Args> |
---|
625 | void addCandidate( Args &&... args ) { |
---|
626 | candidates.emplace_back( new Candidate{ std::forward<Args>( args )... } ); |
---|
627 | reason.code = NoReason; |
---|
628 | } |
---|
629 | |
---|
630 | void postvisit( const ast::ApplicationExpr * applicationExpr ) { |
---|
631 | addCandidate( applicationExpr, tenv ); |
---|
632 | } |
---|
633 | |
---|
634 | /// Set up candidate assertions for inference |
---|
635 | void inferParameters( CandidateRef & newCand, CandidateList & out ) { |
---|
636 | // Set need bindings for any unbound assertions |
---|
637 | UniqueId crntResnSlot = 0; // matching ID for this expression's assertions |
---|
638 | for ( auto & assn : newCand->need ) { |
---|
639 | // skip already-matched assertions |
---|
640 | if ( assn.second.resnSlot != 0 ) continue; |
---|
641 | // assign slot for expression if needed |
---|
642 | if ( crntResnSlot == 0 ) { crntResnSlot = ++globalResnSlot; } |
---|
643 | // fix slot to assertion |
---|
644 | assn.second.resnSlot = crntResnSlot; |
---|
645 | } |
---|
646 | // pair slot to expression |
---|
647 | if ( crntResnSlot != 0 ) { |
---|
648 | newCand->expr.get_and_mutate()->inferred.resnSlots().emplace_back( crntResnSlot ); |
---|
649 | } |
---|
650 | |
---|
651 | // add to output list; assertion satisfaction will occur later |
---|
652 | out.emplace_back( newCand ); |
---|
653 | } |
---|
654 | |
---|
655 | /// Completes a function candidate with arguments located |
---|
656 | void validateFunctionCandidate( |
---|
657 | const CandidateRef & func, ArgPack & result, const std::vector< ArgPack > & results, |
---|
658 | CandidateList & out |
---|
659 | ) { |
---|
660 | ast::ApplicationExpr * appExpr = |
---|
661 | new ast::ApplicationExpr{ func->expr->location, func->expr }; |
---|
662 | // sum cost and accumulate arguments |
---|
663 | std::deque< const ast::Expr * > args; |
---|
664 | Cost cost = func->cost; |
---|
665 | const ArgPack * pack = &result; |
---|
666 | while ( pack->expr ) { |
---|
667 | args.emplace_front( pack->expr ); |
---|
668 | cost += pack->cost; |
---|
669 | pack = &results[pack->parent]; |
---|
670 | } |
---|
671 | std::vector< ast::ptr< ast::Expr > > vargs( args.begin(), args.end() ); |
---|
672 | appExpr->args = move( vargs ); |
---|
673 | // build and validate new candidate |
---|
674 | auto newCand = |
---|
675 | std::make_shared<Candidate>( appExpr, result.env, result.open, result.need, cost ); |
---|
676 | PRINT( |
---|
677 | std::cerr << "instantiate function success: " << appExpr << std::endl; |
---|
678 | std::cerr << "need assertions:" << std::endl; |
---|
679 | ast::print( std::cerr, result.need, 2 ); |
---|
680 | ) |
---|
681 | inferParameters( newCand, out ); |
---|
682 | } |
---|
683 | |
---|
684 | /// Builds a list of candidates for a function, storing them in out |
---|
685 | void makeFunctionCandidates( |
---|
686 | const CandidateRef & func, const ast::FunctionType * funcType, |
---|
687 | const ExplodedArgs_new & args, CandidateList & out |
---|
688 | ) { |
---|
689 | ast::OpenVarSet funcOpen; |
---|
690 | ast::AssertionSet funcNeed, funcHave; |
---|
691 | ast::TypeEnvironment funcEnv{ func->env }; |
---|
692 | makeUnifiableVars( funcType, funcOpen, funcNeed ); |
---|
693 | // add all type variables as open variables now so that those not used in the |
---|
694 | // parameter list are still considered open |
---|
695 | funcEnv.add( funcType->forall ); |
---|
696 | |
---|
697 | if ( targetType && ! targetType->isVoid() && ! funcType->returns.empty() ) { |
---|
698 | // attempt to narrow based on expected target type |
---|
699 | const ast::Type * returnType = funcType->returns.front()->get_type(); |
---|
700 | if ( ! unify( |
---|
701 | returnType, targetType, funcEnv, funcNeed, funcHave, funcOpen, symtab ) |
---|
702 | ) { |
---|
703 | // unification failed, do not pursue this candidate |
---|
704 | return; |
---|
705 | } |
---|
706 | } |
---|
707 | |
---|
708 | // iteratively build matches, one parameter at a time |
---|
709 | std::vector< ArgPack > results; |
---|
710 | results.emplace_back( funcEnv, funcNeed, funcHave, funcOpen ); |
---|
711 | std::size_t genStart = 0; |
---|
712 | |
---|
713 | for ( const ast::DeclWithType * param : funcType->params ) { |
---|
714 | auto obj = strict_dynamic_cast< const ast::ObjectDecl * >( param ); |
---|
715 | // Try adding the arguments corresponding to the current parameter to the existing |
---|
716 | // matches |
---|
717 | if ( ! instantiateArgument( |
---|
718 | obj->type, obj->init, args, results, genStart, symtab ) ) return; |
---|
719 | } |
---|
720 | |
---|
721 | if ( funcType->isVarArgs ) { |
---|
722 | // append any unused arguments to vararg pack |
---|
723 | std::size_t genEnd; |
---|
724 | do { |
---|
725 | genEnd = results.size(); |
---|
726 | |
---|
727 | // iterate results |
---|
728 | for ( std::size_t i = genStart; i < genEnd; ++i ) { |
---|
729 | unsigned nextArg = results[i].nextArg; |
---|
730 | |
---|
731 | // use remainder of exploded tuple if present |
---|
732 | if ( results[i].hasExpl() ) { |
---|
733 | const ExplodedArg & expl = results[i].getExpl( args ); |
---|
734 | |
---|
735 | unsigned nextExpl = results[i].nextExpl + 1; |
---|
736 | if ( nextExpl == expl.exprs.size() ) { nextExpl = 0; } |
---|
737 | |
---|
738 | results.emplace_back( |
---|
739 | i, expl.exprs[ results[i].nextExpl ], copy( results[i].env ), |
---|
740 | copy( results[i].need ), copy( results[i].have ), |
---|
741 | copy( results[i].open ), nextArg, 0, Cost::zero, nextExpl, |
---|
742 | results[i].explAlt ); |
---|
743 | |
---|
744 | continue; |
---|
745 | } |
---|
746 | |
---|
747 | // finish result when out of arguments |
---|
748 | if ( nextArg >= args.size() ) { |
---|
749 | validateFunctionCandidate( func, results[i], results, out ); |
---|
750 | |
---|
751 | continue; |
---|
752 | } |
---|
753 | |
---|
754 | // add each possible next argument |
---|
755 | for ( std::size_t j = 0; j < args[nextArg].size(); ++j ) { |
---|
756 | const ExplodedArg & expl = args[nextArg][j]; |
---|
757 | |
---|
758 | // fresh copies of parent parameters for this iteration |
---|
759 | ast::TypeEnvironment env = results[i].env; |
---|
760 | ast::OpenVarSet open = results[i].open; |
---|
761 | |
---|
762 | env.addActual( expl.env, open ); |
---|
763 | |
---|
764 | // skip empty tuple arguments by (nearly) cloning parent into next gen |
---|
765 | if ( expl.exprs.empty() ) { |
---|
766 | results.emplace_back( |
---|
767 | results[i], move( env ), copy( results[i].need ), |
---|
768 | copy( results[i].have ), move( open ), nextArg + 1, |
---|
769 | expl.cost ); |
---|
770 | |
---|
771 | continue; |
---|
772 | } |
---|
773 | |
---|
774 | // add new result |
---|
775 | results.emplace_back( |
---|
776 | i, expl.exprs.front(), move( env ), copy( results[i].need ), |
---|
777 | copy( results[i].have ), move( open ), nextArg + 1, 0, expl.cost, |
---|
778 | expl.exprs.size() == 1 ? 0 : 1, j ); |
---|
779 | } |
---|
780 | } |
---|
781 | |
---|
782 | genStart = genEnd; |
---|
783 | } while( genEnd != results.size() ); |
---|
784 | } else { |
---|
785 | // filter out the results that don't use all the arguments |
---|
786 | for ( std::size_t i = genStart; i < results.size(); ++i ) { |
---|
787 | ArgPack & result = results[i]; |
---|
788 | if ( ! result.hasExpl() && result.nextArg >= args.size() ) { |
---|
789 | validateFunctionCandidate( func, result, results, out ); |
---|
790 | } |
---|
791 | } |
---|
792 | } |
---|
793 | } |
---|
794 | |
---|
795 | /// Adds implicit struct-conversions to the alternative list |
---|
796 | void addAnonConversions( const CandidateRef & cand ) { |
---|
797 | // adds anonymous member interpretations whenever an aggregate value type is seen. |
---|
798 | // it's okay for the aggregate expression to have reference type -- cast it to the |
---|
799 | // base type to treat the aggregate as the referenced value |
---|
800 | ast::ptr< ast::Expr > aggrExpr( cand->expr ); |
---|
801 | ast::ptr< ast::Type > & aggrType = aggrExpr.get_and_mutate()->result; |
---|
802 | cand->env.apply( aggrType ); |
---|
803 | |
---|
804 | if ( aggrType.as< ast::ReferenceType >() ) { |
---|
805 | aggrExpr = new ast::CastExpr{ aggrExpr, aggrType->stripReferences() }; |
---|
806 | } |
---|
807 | |
---|
808 | if ( auto structInst = aggrExpr->result.as< ast::StructInstType >() ) { |
---|
809 | addAggMembers( structInst, aggrExpr, *cand, Cost::safe, "" ); |
---|
810 | } else if ( auto unionInst = aggrExpr->result.as< ast::UnionInstType >() ) { |
---|
811 | addAggMembers( unionInst, aggrExpr, *cand, Cost::safe, "" ); |
---|
812 | } |
---|
813 | } |
---|
814 | |
---|
815 | /// Adds aggregate member interpretations |
---|
816 | void addAggMembers( |
---|
817 | const ast::ReferenceToType * aggrInst, const ast::Expr * expr, |
---|
818 | const Candidate & cand, const Cost & addedCost, const std::string & name |
---|
819 | ) { |
---|
820 | for ( const ast::Decl * decl : aggrInst->lookup( name ) ) { |
---|
821 | auto dwt = strict_dynamic_cast< const ast::DeclWithType * >( decl ); |
---|
822 | CandidateRef newCand = std::make_shared<Candidate>( |
---|
823 | cand, new ast::MemberExpr{ expr->location, dwt, expr }, addedCost ); |
---|
824 | // add anonymous member interpretations whenever an aggregate value type is seen |
---|
825 | // as a member expression |
---|
826 | addAnonConversions( newCand ); |
---|
827 | candidates.emplace_back( move( newCand ) ); |
---|
828 | } |
---|
829 | } |
---|
830 | |
---|
831 | /// Adds tuple member interpretations |
---|
832 | void addTupleMembers( |
---|
833 | const ast::TupleType * tupleType, const ast::Expr * expr, const Candidate & cand, |
---|
834 | const Cost & addedCost, const ast::Expr * member |
---|
835 | ) { |
---|
836 | if ( auto constantExpr = dynamic_cast< const ast::ConstantExpr * >( member ) ) { |
---|
837 | // get the value of the constant expression as an int, must be between 0 and the |
---|
838 | // length of the tuple to have meaning |
---|
839 | long long val = constantExpr->intValue(); |
---|
840 | if ( val >= 0 && (unsigned long long)val < tupleType->size() ) { |
---|
841 | addCandidate( |
---|
842 | cand, new ast::TupleIndexExpr{ expr->location, expr, (unsigned)val }, |
---|
843 | addedCost ); |
---|
844 | } |
---|
845 | } |
---|
846 | } |
---|
847 | |
---|
848 | void postvisit( const ast::UntypedExpr * untypedExpr ) { |
---|
849 | CandidateFinder funcFinder{ symtab, tenv }; |
---|
850 | funcFinder.find( untypedExpr->func, ResolvMode::withAdjustment() ); |
---|
851 | // short-circuit if no candidates |
---|
852 | if ( funcFinder.candidates.empty() ) return; |
---|
853 | |
---|
854 | reason.code = NoMatch; |
---|
855 | |
---|
856 | std::vector< CandidateFinder > argCandidates = |
---|
857 | selfFinder.findSubExprs( untypedExpr->args ); |
---|
858 | |
---|
859 | // take care of possible tuple assignments |
---|
860 | // if not tuple assignment, handled as normal function call |
---|
861 | Tuples::handleTupleAssignment( selfFinder, untypedExpr, argCandidates ); |
---|
862 | |
---|
863 | // find function operators |
---|
864 | ast::ptr< ast::Expr > opExpr = new ast::NameExpr{ untypedExpr->location, "?()" }; |
---|
865 | CandidateFinder opFinder{ symtab, tenv }; |
---|
866 | // okay if there aren't any function operations |
---|
867 | opFinder.find( opExpr, ResolvMode::withoutFailFast() ); |
---|
868 | PRINT( |
---|
869 | std::cerr << "known function ops:" << std::endl; |
---|
870 | print( std::cerr, opFinder.candidates, 1 ); |
---|
871 | ) |
---|
872 | |
---|
873 | // pre-explode arguments |
---|
874 | ExplodedArgs_new argExpansions; |
---|
875 | for ( const CandidateFinder & args : argCandidates ) { |
---|
876 | argExpansions.emplace_back(); |
---|
877 | auto & argE = argExpansions.back(); |
---|
878 | for ( const CandidateRef & arg : args ) { argE.emplace_back( *arg, symtab ); } |
---|
879 | } |
---|
880 | |
---|
881 | // Find function matches |
---|
882 | CandidateList found; |
---|
883 | SemanticErrorException errors; |
---|
884 | for ( CandidateRef & func : funcFinder ) { |
---|
885 | try { |
---|
886 | PRINT( |
---|
887 | std::cerr << "working on alternative:" << std::endl; |
---|
888 | print( std::cerr, *func, 2 ); |
---|
889 | ) |
---|
890 | |
---|
891 | // check if the type is a pointer to function |
---|
892 | const ast::Type * funcResult = func->expr->result->stripReferences(); |
---|
893 | if ( auto pointer = dynamic_cast< const ast::PointerType * >( funcResult ) ) { |
---|
894 | if ( auto function = pointer->base.as< ast::FunctionType >() ) { |
---|
895 | CandidateRef newFunc{ new Candidate{ *func } }; |
---|
896 | newFunc->expr = |
---|
897 | referenceToRvalueConversion( newFunc->expr, newFunc->cost ); |
---|
898 | makeFunctionCandidates( newFunc, function, argExpansions, found ); |
---|
899 | } |
---|
900 | } else if ( |
---|
901 | auto inst = dynamic_cast< const ast::TypeInstType * >( funcResult ) |
---|
902 | ) { |
---|
903 | if ( const ast::EqvClass * clz = func->env.lookup( inst->name ) ) { |
---|
904 | if ( auto function = clz->bound.as< ast::FunctionType >() ) { |
---|
905 | CandidateRef newFunc{ new Candidate{ *func } }; |
---|
906 | newFunc->expr = |
---|
907 | referenceToRvalueConversion( newFunc->expr, newFunc->cost ); |
---|
908 | makeFunctionCandidates( newFunc, function, argExpansions, found ); |
---|
909 | } |
---|
910 | } |
---|
911 | } |
---|
912 | } catch ( SemanticErrorException & e ) { errors.append( e ); } |
---|
913 | } |
---|
914 | |
---|
915 | // Find matches on function operators `?()` |
---|
916 | if ( ! opFinder.candidates.empty() ) { |
---|
917 | // add exploded function alternatives to front of argument list |
---|
918 | std::vector< ExplodedArg > funcE; |
---|
919 | funcE.reserve( funcFinder.candidates.size() ); |
---|
920 | for ( const CandidateRef & func : funcFinder ) { |
---|
921 | funcE.emplace_back( *func, symtab ); |
---|
922 | } |
---|
923 | argExpansions.emplace_front( move( funcE ) ); |
---|
924 | |
---|
925 | for ( const CandidateRef & op : opFinder ) { |
---|
926 | try { |
---|
927 | // check if type is pointer-to-function |
---|
928 | const ast::Type * opResult = op->expr->result->stripReferences(); |
---|
929 | if ( auto pointer = dynamic_cast< const ast::PointerType * >( opResult ) ) { |
---|
930 | if ( auto function = pointer->base.as< ast::FunctionType >() ) { |
---|
931 | CandidateRef newOp{ new Candidate{ *op} }; |
---|
932 | newOp->expr = |
---|
933 | referenceToRvalueConversion( newOp->expr, newOp->cost ); |
---|
934 | makeFunctionCandidates( newOp, function, argExpansions, found ); |
---|
935 | } |
---|
936 | } |
---|
937 | } catch ( SemanticErrorException & e ) { errors.append( e ); } |
---|
938 | } |
---|
939 | } |
---|
940 | |
---|
941 | // Implement SFINAE; resolution errors are only errors if there aren't any non-error |
---|
942 | // candidates |
---|
943 | if ( found.empty() && ! errors.isEmpty() ) { throw errors; } |
---|
944 | |
---|
945 | // Compute conversion costs |
---|
946 | for ( CandidateRef & withFunc : found ) { |
---|
947 | Cost cvtCost = computeApplicationConversionCost( withFunc, symtab ); |
---|
948 | |
---|
949 | PRINT( |
---|
950 | auto appExpr = withFunc->expr.strict_as< ast::ApplicationExpr >(); |
---|
951 | auto pointer = appExpr->func->result.strict_as< ast::PointerType >(); |
---|
952 | auto function = pointer->base.strict_as< ast::FunctionType >(); |
---|
953 | |
---|
954 | std::cerr << "Case +++++++++++++ " << appExpr->func << std::endl; |
---|
955 | std::cerr << "parameters are:" << std::endl; |
---|
956 | ast::printAll( std::cerr, function->params, 2 ); |
---|
957 | std::cerr << "arguments are:" << std::endl; |
---|
958 | ast::printAll( std::cerr, appExpr->args, 2 ); |
---|
959 | std::cerr << "bindings are:" << std::endl; |
---|
960 | ast::print( std::cerr, withFunc->env, 2 ); |
---|
961 | std::cerr << "cost is: " << withFunc->cost << std::endl; |
---|
962 | std::cerr << "cost of conversion is:" << cvtCost << std::endl; |
---|
963 | ) |
---|
964 | |
---|
965 | if ( cvtCost != Cost::infinity ) { |
---|
966 | withFunc->cvtCost = cvtCost; |
---|
967 | candidates.emplace_back( move( withFunc ) ); |
---|
968 | } |
---|
969 | } |
---|
970 | found = move( candidates ); |
---|
971 | |
---|
972 | // use a new list so that candidates are not examined by addAnonConversions twice |
---|
973 | CandidateList winners = findMinCost( found ); |
---|
974 | promoteCvtCost( winners ); |
---|
975 | |
---|
976 | // function may return a struct/union value, in which case we need to add candidates |
---|
977 | // for implicit conversions to each of the anonymous members, which must happen after |
---|
978 | // `findMinCost`, since anon conversions are never the cheapest |
---|
979 | for ( const CandidateRef & c : winners ) { |
---|
980 | addAnonConversions( c ); |
---|
981 | } |
---|
982 | spliceBegin( candidates, winners ); |
---|
983 | |
---|
984 | if ( candidates.empty() && targetType && ! targetType->isVoid() ) { |
---|
985 | // If resolution is unsuccessful with a target type, try again without, since it |
---|
986 | // will sometimes succeed when it wouldn't with a target type binding. |
---|
987 | // For example: |
---|
988 | // forall( otype T ) T & ?[]( T *, ptrdiff_t ); |
---|
989 | // const char * x = "hello world"; |
---|
990 | // unsigned char ch = x[0]; |
---|
991 | // Fails with simple return type binding (xxx -- check this!) as follows: |
---|
992 | // * T is bound to unsigned char |
---|
993 | // * (x: const char *) is unified with unsigned char *, which fails |
---|
994 | // xxx -- fix this better |
---|
995 | targetType = nullptr; |
---|
996 | postvisit( untypedExpr ); |
---|
997 | } |
---|
998 | } |
---|
999 | |
---|
1000 | /// true if expression is an lvalue |
---|
1001 | static bool isLvalue( const ast::Expr * x ) { |
---|
1002 | return x->result && ( x->get_lvalue() || x->result.as< ast::ReferenceType >() ); |
---|
1003 | } |
---|
1004 | |
---|
1005 | void postvisit( const ast::AddressExpr * addressExpr ) { |
---|
1006 | CandidateFinder finder{ symtab, tenv }; |
---|
1007 | finder.find( addressExpr->arg ); |
---|
1008 | |
---|
1009 | if( finder.candidates.empty() ) return; |
---|
1010 | |
---|
1011 | reason.code = NoMatch; |
---|
1012 | |
---|
1013 | for ( CandidateRef & r : finder.candidates ) { |
---|
1014 | if ( ! isLvalue( r->expr ) ) continue; |
---|
1015 | addCandidate( *r, new ast::AddressExpr{ addressExpr->location, r->expr } ); |
---|
1016 | } |
---|
1017 | } |
---|
1018 | |
---|
1019 | void postvisit( const ast::LabelAddressExpr * labelExpr ) { |
---|
1020 | addCandidate( labelExpr, tenv ); |
---|
1021 | } |
---|
1022 | |
---|
1023 | void postvisit( const ast::CastExpr * castExpr ) { |
---|
1024 | ast::ptr< ast::Type > toType = castExpr->result; |
---|
1025 | assert( toType ); |
---|
1026 | toType = resolveTypeof( toType, symtab ); |
---|
1027 | toType = SymTab::validateType( castExpr->location, toType, symtab ); |
---|
1028 | toType = adjustExprType( toType, tenv, symtab ); |
---|
1029 | |
---|
1030 | CandidateFinder finder{ symtab, tenv, toType }; |
---|
1031 | finder.find( castExpr->arg, ResolvMode::withAdjustment() ); |
---|
1032 | |
---|
1033 | if( !finder.candidates.empty() ) reason.code = NoMatch; |
---|
1034 | |
---|
1035 | CandidateList matches; |
---|
1036 | for ( CandidateRef & cand : finder.candidates ) { |
---|
1037 | ast::AssertionSet need( cand->need.begin(), cand->need.end() ), have; |
---|
1038 | ast::OpenVarSet open( cand->open ); |
---|
1039 | |
---|
1040 | cand->env.extractOpenVars( open ); |
---|
1041 | |
---|
1042 | // It is possible that a cast can throw away some values in a multiply-valued |
---|
1043 | // expression, e.g. cast-to-void, one value to zero. Figure out the prefix of the |
---|
1044 | // subexpression results that are cast directly. The candidate is invalid if it |
---|
1045 | // has fewer results than there are types to cast to. |
---|
1046 | int discardedValues = cand->expr->result->size() - toType->size(); |
---|
1047 | if ( discardedValues < 0 ) continue; |
---|
1048 | |
---|
1049 | // unification run for side-effects |
---|
1050 | unify( toType, cand->expr->result, cand->env, need, have, open, symtab ); |
---|
1051 | Cost thisCost = castCost( cand->expr->result, toType, cand->expr->get_lvalue(), |
---|
1052 | symtab, cand->env ); |
---|
1053 | PRINT( |
---|
1054 | std::cerr << "working on cast with result: " << toType << std::endl; |
---|
1055 | std::cerr << "and expr type: " << cand->expr->result << std::endl; |
---|
1056 | std::cerr << "env: " << cand->env << std::endl; |
---|
1057 | ) |
---|
1058 | if ( thisCost != Cost::infinity ) { |
---|
1059 | PRINT( |
---|
1060 | std::cerr << "has finite cost." << std::endl; |
---|
1061 | ) |
---|
1062 | // count one safe conversion for each value that is thrown away |
---|
1063 | thisCost.incSafe( discardedValues ); |
---|
1064 | CandidateRef newCand = std::make_shared<Candidate>( |
---|
1065 | restructureCast( cand->expr, toType, castExpr->isGenerated ), |
---|
1066 | copy( cand->env ), move( open ), move( need ), cand->cost, |
---|
1067 | cand->cost + thisCost ); |
---|
1068 | inferParameters( newCand, matches ); |
---|
1069 | } |
---|
1070 | } |
---|
1071 | |
---|
1072 | // select first on argument cost, then conversion cost |
---|
1073 | CandidateList minArgCost = findMinCost( matches ); |
---|
1074 | promoteCvtCost( minArgCost ); |
---|
1075 | candidates = findMinCost( minArgCost ); |
---|
1076 | } |
---|
1077 | |
---|
1078 | void postvisit( const ast::VirtualCastExpr * castExpr ) { |
---|
1079 | assertf( castExpr->result, "Implicit virtual cast targets not yet supported." ); |
---|
1080 | CandidateFinder finder{ symtab, tenv }; |
---|
1081 | // don't prune here, all alternatives guaranteed to have same type |
---|
1082 | finder.find( castExpr->arg, ResolvMode::withoutPrune() ); |
---|
1083 | for ( CandidateRef & r : finder.candidates ) { |
---|
1084 | addCandidate( |
---|
1085 | *r, |
---|
1086 | new ast::VirtualCastExpr{ castExpr->location, r->expr, castExpr->result } ); |
---|
1087 | } |
---|
1088 | } |
---|
1089 | |
---|
1090 | void postvisit( const ast::UntypedMemberExpr * memberExpr ) { |
---|
1091 | CandidateFinder aggFinder{ symtab, tenv }; |
---|
1092 | aggFinder.find( memberExpr->aggregate, ResolvMode::withAdjustment() ); |
---|
1093 | for ( CandidateRef & agg : aggFinder.candidates ) { |
---|
1094 | // it's okay for the aggregate expression to have reference type -- cast it to the |
---|
1095 | // base type to treat the aggregate as the referenced value |
---|
1096 | Cost addedCost = Cost::zero; |
---|
1097 | agg->expr = referenceToRvalueConversion( agg->expr, addedCost ); |
---|
1098 | |
---|
1099 | // find member of the given type |
---|
1100 | if ( auto structInst = agg->expr->result.as< ast::StructInstType >() ) { |
---|
1101 | addAggMembers( |
---|
1102 | structInst, agg->expr, *agg, addedCost, getMemberName( memberExpr ) ); |
---|
1103 | } else if ( auto unionInst = agg->expr->result.as< ast::UnionInstType >() ) { |
---|
1104 | addAggMembers( |
---|
1105 | unionInst, agg->expr, *agg, addedCost, getMemberName( memberExpr ) ); |
---|
1106 | } else if ( auto tupleType = agg->expr->result.as< ast::TupleType >() ) { |
---|
1107 | addTupleMembers( tupleType, agg->expr, *agg, addedCost, memberExpr->member ); |
---|
1108 | } |
---|
1109 | } |
---|
1110 | } |
---|
1111 | |
---|
1112 | void postvisit( const ast::MemberExpr * memberExpr ) { |
---|
1113 | addCandidate( memberExpr, tenv ); |
---|
1114 | } |
---|
1115 | |
---|
1116 | void postvisit( const ast::NameExpr * nameExpr ) { |
---|
1117 | std::vector< ast::SymbolTable::IdData > declList = symtab.lookupId( nameExpr->name ); |
---|
1118 | PRINT( std::cerr << "nameExpr is " << nameExpr->name << std::endl; ) |
---|
1119 | if( declList.empty() ) return; |
---|
1120 | |
---|
1121 | reason.code = NoMatch; |
---|
1122 | |
---|
1123 | for ( auto & data : declList ) { |
---|
1124 | Cost cost = Cost::zero; |
---|
1125 | ast::Expr * newExpr = data.combine( nameExpr->location, cost ); |
---|
1126 | |
---|
1127 | CandidateRef newCand = std::make_shared<Candidate>( |
---|
1128 | newExpr, copy( tenv ), ast::OpenVarSet{}, ast::AssertionSet{}, Cost::zero, |
---|
1129 | cost ); |
---|
1130 | PRINT( |
---|
1131 | std::cerr << "decl is "; |
---|
1132 | ast::print( std::cerr, data.id ); |
---|
1133 | std::cerr << std::endl; |
---|
1134 | std::cerr << "newExpr is "; |
---|
1135 | ast::print( std::cerr, newExpr ); |
---|
1136 | std::cerr << std::endl; |
---|
1137 | ) |
---|
1138 | newCand->expr = ast::mutate_field( |
---|
1139 | newCand->expr.get(), &ast::Expr::result, |
---|
1140 | renameTyVars( newCand->expr->result ) ); |
---|
1141 | // add anonymous member interpretations whenever an aggregate value type is seen |
---|
1142 | // as a name expression |
---|
1143 | addAnonConversions( newCand ); |
---|
1144 | candidates.emplace_back( move( newCand ) ); |
---|
1145 | } |
---|
1146 | } |
---|
1147 | |
---|
1148 | void postvisit( const ast::VariableExpr * variableExpr ) { |
---|
1149 | // not sufficient to just pass `variableExpr` here, type might have changed since |
---|
1150 | // creation |
---|
1151 | addCandidate( |
---|
1152 | new ast::VariableExpr{ variableExpr->location, variableExpr->var }, tenv ); |
---|
1153 | } |
---|
1154 | |
---|
1155 | void postvisit( const ast::ConstantExpr * constantExpr ) { |
---|
1156 | addCandidate( constantExpr, tenv ); |
---|
1157 | } |
---|
1158 | |
---|
1159 | void postvisit( const ast::SizeofExpr * sizeofExpr ) { |
---|
1160 | if ( sizeofExpr->type ) { |
---|
1161 | addCandidate( |
---|
1162 | new ast::SizeofExpr{ |
---|
1163 | sizeofExpr->location, resolveTypeof( sizeofExpr->type, symtab ) }, |
---|
1164 | tenv ); |
---|
1165 | } else { |
---|
1166 | // find all candidates for the argument to sizeof |
---|
1167 | CandidateFinder finder{ symtab, tenv }; |
---|
1168 | finder.find( sizeofExpr->expr ); |
---|
1169 | // find the lowest-cost candidate, otherwise ambiguous |
---|
1170 | CandidateList winners = findMinCost( finder.candidates ); |
---|
1171 | if ( winners.size() != 1 ) { |
---|
1172 | SemanticError( |
---|
1173 | sizeofExpr->expr.get(), "Ambiguous expression in sizeof operand: " ); |
---|
1174 | } |
---|
1175 | // return the lowest-cost candidate |
---|
1176 | CandidateRef & choice = winners.front(); |
---|
1177 | choice->expr = referenceToRvalueConversion( choice->expr, choice->cost ); |
---|
1178 | choice->cost = Cost::zero; |
---|
1179 | addCandidate( *choice, new ast::SizeofExpr{ sizeofExpr->location, choice->expr } ); |
---|
1180 | } |
---|
1181 | } |
---|
1182 | |
---|
1183 | void postvisit( const ast::AlignofExpr * alignofExpr ) { |
---|
1184 | if ( alignofExpr->type ) { |
---|
1185 | addCandidate( |
---|
1186 | new ast::AlignofExpr{ |
---|
1187 | alignofExpr->location, resolveTypeof( alignofExpr->type, symtab ) }, |
---|
1188 | tenv ); |
---|
1189 | } else { |
---|
1190 | // find all candidates for the argument to alignof |
---|
1191 | CandidateFinder finder{ symtab, tenv }; |
---|
1192 | finder.find( alignofExpr->expr ); |
---|
1193 | // find the lowest-cost candidate, otherwise ambiguous |
---|
1194 | CandidateList winners = findMinCost( finder.candidates ); |
---|
1195 | if ( winners.size() != 1 ) { |
---|
1196 | SemanticError( |
---|
1197 | alignofExpr->expr.get(), "Ambiguous expression in alignof operand: " ); |
---|
1198 | } |
---|
1199 | // return the lowest-cost candidate |
---|
1200 | CandidateRef & choice = winners.front(); |
---|
1201 | choice->expr = referenceToRvalueConversion( choice->expr, choice->cost ); |
---|
1202 | choice->cost = Cost::zero; |
---|
1203 | addCandidate( |
---|
1204 | *choice, new ast::AlignofExpr{ alignofExpr->location, choice->expr } ); |
---|
1205 | } |
---|
1206 | } |
---|
1207 | |
---|
1208 | void postvisit( const ast::UntypedOffsetofExpr * offsetofExpr ) { |
---|
1209 | const ast::ReferenceToType * aggInst; |
---|
1210 | if (( aggInst = offsetofExpr->type.as< ast::StructInstType >() )) ; |
---|
1211 | else if (( aggInst = offsetofExpr->type.as< ast::UnionInstType >() )) ; |
---|
1212 | else return; |
---|
1213 | |
---|
1214 | for ( const ast::Decl * member : aggInst->lookup( offsetofExpr->member ) ) { |
---|
1215 | auto dwt = strict_dynamic_cast< const ast::DeclWithType * >( member ); |
---|
1216 | addCandidate( |
---|
1217 | new ast::OffsetofExpr{ offsetofExpr->location, aggInst, dwt }, tenv ); |
---|
1218 | } |
---|
1219 | } |
---|
1220 | |
---|
1221 | void postvisit( const ast::OffsetofExpr * offsetofExpr ) { |
---|
1222 | addCandidate( offsetofExpr, tenv ); |
---|
1223 | } |
---|
1224 | |
---|
1225 | void postvisit( const ast::OffsetPackExpr * offsetPackExpr ) { |
---|
1226 | addCandidate( offsetPackExpr, tenv ); |
---|
1227 | } |
---|
1228 | |
---|
1229 | void postvisit( const ast::LogicalExpr * logicalExpr ) { |
---|
1230 | CandidateFinder finder1{ symtab, tenv }; |
---|
1231 | finder1.find( logicalExpr->arg1, ResolvMode::withAdjustment() ); |
---|
1232 | if ( finder1.candidates.empty() ) return; |
---|
1233 | |
---|
1234 | CandidateFinder finder2{ symtab, tenv }; |
---|
1235 | finder2.find( logicalExpr->arg2, ResolvMode::withAdjustment() ); |
---|
1236 | if ( finder2.candidates.empty() ) return; |
---|
1237 | |
---|
1238 | reason.code = NoMatch; |
---|
1239 | |
---|
1240 | for ( const CandidateRef & r1 : finder1.candidates ) { |
---|
1241 | for ( const CandidateRef & r2 : finder2.candidates ) { |
---|
1242 | ast::TypeEnvironment env{ r1->env }; |
---|
1243 | env.simpleCombine( r2->env ); |
---|
1244 | ast::OpenVarSet open{ r1->open }; |
---|
1245 | mergeOpenVars( open, r2->open ); |
---|
1246 | ast::AssertionSet need; |
---|
1247 | mergeAssertionSet( need, r1->need ); |
---|
1248 | mergeAssertionSet( need, r2->need ); |
---|
1249 | |
---|
1250 | addCandidate( |
---|
1251 | new ast::LogicalExpr{ |
---|
1252 | logicalExpr->location, r1->expr, r2->expr, logicalExpr->isAnd }, |
---|
1253 | move( env ), move( open ), move( need ), r1->cost + r2->cost ); |
---|
1254 | } |
---|
1255 | } |
---|
1256 | } |
---|
1257 | |
---|
1258 | void postvisit( const ast::ConditionalExpr * conditionalExpr ) { |
---|
1259 | // candidates for condition |
---|
1260 | CandidateFinder finder1{ symtab, tenv }; |
---|
1261 | finder1.find( conditionalExpr->arg1, ResolvMode::withAdjustment() ); |
---|
1262 | if ( finder1.candidates.empty() ) return; |
---|
1263 | |
---|
1264 | // candidates for true result |
---|
1265 | CandidateFinder finder2{ symtab, tenv }; |
---|
1266 | finder2.find( conditionalExpr->arg2, ResolvMode::withAdjustment() ); |
---|
1267 | if ( finder2.candidates.empty() ) return; |
---|
1268 | |
---|
1269 | // candidates for false result |
---|
1270 | CandidateFinder finder3{ symtab, tenv }; |
---|
1271 | finder3.find( conditionalExpr->arg3, ResolvMode::withAdjustment() ); |
---|
1272 | if ( finder3.candidates.empty() ) return; |
---|
1273 | |
---|
1274 | reason.code = NoMatch; |
---|
1275 | |
---|
1276 | for ( const CandidateRef & r1 : finder1.candidates ) { |
---|
1277 | for ( const CandidateRef & r2 : finder2.candidates ) { |
---|
1278 | for ( const CandidateRef & r3 : finder3.candidates ) { |
---|
1279 | ast::TypeEnvironment env{ r1->env }; |
---|
1280 | env.simpleCombine( r2->env ); |
---|
1281 | env.simpleCombine( r3->env ); |
---|
1282 | ast::OpenVarSet open{ r1->open }; |
---|
1283 | mergeOpenVars( open, r2->open ); |
---|
1284 | mergeOpenVars( open, r3->open ); |
---|
1285 | ast::AssertionSet need; |
---|
1286 | mergeAssertionSet( need, r1->need ); |
---|
1287 | mergeAssertionSet( need, r2->need ); |
---|
1288 | mergeAssertionSet( need, r3->need ); |
---|
1289 | ast::AssertionSet have; |
---|
1290 | |
---|
1291 | // unify true and false results, then infer parameters to produce new |
---|
1292 | // candidates |
---|
1293 | ast::ptr< ast::Type > common; |
---|
1294 | if ( |
---|
1295 | unify( |
---|
1296 | r2->expr->result, r3->expr->result, env, need, have, open, symtab, |
---|
1297 | common ) |
---|
1298 | ) { |
---|
1299 | // generate typed expression |
---|
1300 | ast::ConditionalExpr * newExpr = new ast::ConditionalExpr{ |
---|
1301 | conditionalExpr->location, r1->expr, r2->expr, r3->expr }; |
---|
1302 | newExpr->result = common ? common : r2->expr->result; |
---|
1303 | // convert both options to result type |
---|
1304 | Cost cost = r1->cost + r2->cost + r3->cost; |
---|
1305 | newExpr->arg2 = computeExpressionConversionCost( |
---|
1306 | newExpr->arg2, newExpr->result, symtab, env, cost ); |
---|
1307 | newExpr->arg3 = computeExpressionConversionCost( |
---|
1308 | newExpr->arg3, newExpr->result, symtab, env, cost ); |
---|
1309 | // output candidate |
---|
1310 | CandidateRef newCand = std::make_shared<Candidate>( |
---|
1311 | newExpr, move( env ), move( open ), move( need ), cost ); |
---|
1312 | inferParameters( newCand, candidates ); |
---|
1313 | } |
---|
1314 | } |
---|
1315 | } |
---|
1316 | } |
---|
1317 | } |
---|
1318 | |
---|
1319 | void postvisit( const ast::CommaExpr * commaExpr ) { |
---|
1320 | ast::TypeEnvironment env{ tenv }; |
---|
1321 | ast::ptr< ast::Expr > arg1 = resolveInVoidContext( commaExpr->arg1, symtab, env ); |
---|
1322 | |
---|
1323 | CandidateFinder finder2{ symtab, env }; |
---|
1324 | finder2.find( commaExpr->arg2, ResolvMode::withAdjustment() ); |
---|
1325 | |
---|
1326 | for ( const CandidateRef & r2 : finder2.candidates ) { |
---|
1327 | addCandidate( *r2, new ast::CommaExpr{ commaExpr->location, arg1, r2->expr } ); |
---|
1328 | } |
---|
1329 | } |
---|
1330 | |
---|
1331 | void postvisit( const ast::ImplicitCopyCtorExpr * ctorExpr ) { |
---|
1332 | addCandidate( ctorExpr, tenv ); |
---|
1333 | } |
---|
1334 | |
---|
1335 | void postvisit( const ast::ConstructorExpr * ctorExpr ) { |
---|
1336 | CandidateFinder finder{ symtab, tenv }; |
---|
1337 | finder.find( ctorExpr->callExpr, ResolvMode::withoutPrune() ); |
---|
1338 | for ( CandidateRef & r : finder.candidates ) { |
---|
1339 | addCandidate( *r, new ast::ConstructorExpr{ ctorExpr->location, r->expr } ); |
---|
1340 | } |
---|
1341 | } |
---|
1342 | |
---|
1343 | void postvisit( const ast::RangeExpr * rangeExpr ) { |
---|
1344 | // resolve low and high, accept candidates where low and high types unify |
---|
1345 | CandidateFinder finder1{ symtab, tenv }; |
---|
1346 | finder1.find( rangeExpr->low, ResolvMode::withAdjustment() ); |
---|
1347 | if ( finder1.candidates.empty() ) return; |
---|
1348 | |
---|
1349 | CandidateFinder finder2{ symtab, tenv }; |
---|
1350 | finder2.find( rangeExpr->high, ResolvMode::withAdjustment() ); |
---|
1351 | if ( finder2.candidates.empty() ) return; |
---|
1352 | |
---|
1353 | reason.code = NoMatch; |
---|
1354 | |
---|
1355 | for ( const CandidateRef & r1 : finder1.candidates ) { |
---|
1356 | for ( const CandidateRef & r2 : finder2.candidates ) { |
---|
1357 | ast::TypeEnvironment env{ r1->env }; |
---|
1358 | env.simpleCombine( r2->env ); |
---|
1359 | ast::OpenVarSet open{ r1->open }; |
---|
1360 | mergeOpenVars( open, r2->open ); |
---|
1361 | ast::AssertionSet need; |
---|
1362 | mergeAssertionSet( need, r1->need ); |
---|
1363 | mergeAssertionSet( need, r2->need ); |
---|
1364 | ast::AssertionSet have; |
---|
1365 | |
---|
1366 | ast::ptr< ast::Type > common; |
---|
1367 | if ( |
---|
1368 | unify( |
---|
1369 | r1->expr->result, r2->expr->result, env, need, have, open, symtab, |
---|
1370 | common ) |
---|
1371 | ) { |
---|
1372 | // generate new expression |
---|
1373 | ast::RangeExpr * newExpr = |
---|
1374 | new ast::RangeExpr{ rangeExpr->location, r1->expr, r2->expr }; |
---|
1375 | newExpr->result = common ? common : r1->expr->result; |
---|
1376 | // add candidate |
---|
1377 | CandidateRef newCand = std::make_shared<Candidate>( |
---|
1378 | newExpr, move( env ), move( open ), move( need ), |
---|
1379 | r1->cost + r2->cost ); |
---|
1380 | inferParameters( newCand, candidates ); |
---|
1381 | } |
---|
1382 | } |
---|
1383 | } |
---|
1384 | } |
---|
1385 | |
---|
1386 | void postvisit( const ast::UntypedTupleExpr * tupleExpr ) { |
---|
1387 | std::vector< CandidateFinder > subCandidates = |
---|
1388 | selfFinder.findSubExprs( tupleExpr->exprs ); |
---|
1389 | std::vector< CandidateList > possibilities; |
---|
1390 | combos( subCandidates.begin(), subCandidates.end(), back_inserter( possibilities ) ); |
---|
1391 | |
---|
1392 | for ( const CandidateList & subs : possibilities ) { |
---|
1393 | std::vector< ast::ptr< ast::Expr > > exprs; |
---|
1394 | exprs.reserve( subs.size() ); |
---|
1395 | for ( const CandidateRef & sub : subs ) { exprs.emplace_back( sub->expr ); } |
---|
1396 | |
---|
1397 | ast::TypeEnvironment env; |
---|
1398 | ast::OpenVarSet open; |
---|
1399 | ast::AssertionSet need; |
---|
1400 | for ( const CandidateRef & sub : subs ) { |
---|
1401 | env.simpleCombine( sub->env ); |
---|
1402 | mergeOpenVars( open, sub->open ); |
---|
1403 | mergeAssertionSet( need, sub->need ); |
---|
1404 | } |
---|
1405 | |
---|
1406 | addCandidate( |
---|
1407 | new ast::TupleExpr{ tupleExpr->location, move( exprs ) }, |
---|
1408 | move( env ), move( open ), move( need ), sumCost( subs ) ); |
---|
1409 | } |
---|
1410 | } |
---|
1411 | |
---|
1412 | void postvisit( const ast::TupleExpr * tupleExpr ) { |
---|
1413 | addCandidate( tupleExpr, tenv ); |
---|
1414 | } |
---|
1415 | |
---|
1416 | void postvisit( const ast::TupleIndexExpr * tupleExpr ) { |
---|
1417 | addCandidate( tupleExpr, tenv ); |
---|
1418 | } |
---|
1419 | |
---|
1420 | void postvisit( const ast::TupleAssignExpr * tupleExpr ) { |
---|
1421 | addCandidate( tupleExpr, tenv ); |
---|
1422 | } |
---|
1423 | |
---|
1424 | void postvisit( const ast::UniqueExpr * unqExpr ) { |
---|
1425 | CandidateFinder finder{ symtab, tenv }; |
---|
1426 | finder.find( unqExpr->expr, ResolvMode::withAdjustment() ); |
---|
1427 | for ( CandidateRef & r : finder.candidates ) { |
---|
1428 | // ensure that the the id is passed on so that the expressions are "linked" |
---|
1429 | addCandidate( *r, new ast::UniqueExpr{ unqExpr->location, r->expr, unqExpr->id } ); |
---|
1430 | } |
---|
1431 | } |
---|
1432 | |
---|
1433 | void postvisit( const ast::StmtExpr * stmtExpr ) { |
---|
1434 | addCandidate( resolveStmtExpr( stmtExpr, symtab ), tenv ); |
---|
1435 | } |
---|
1436 | |
---|
1437 | void postvisit( const ast::UntypedInitExpr * initExpr ) { |
---|
1438 | // handle each option like a cast |
---|
1439 | CandidateList matches; |
---|
1440 | PRINT( |
---|
1441 | std::cerr << "untyped init expr: " << initExpr << std::endl; |
---|
1442 | ) |
---|
1443 | // O(n^2) checks of d-types with e-types |
---|
1444 | for ( const ast::InitAlternative & initAlt : initExpr->initAlts ) { |
---|
1445 | // calculate target type |
---|
1446 | const ast::Type * toType = resolveTypeof( initAlt.type, symtab ); |
---|
1447 | toType = SymTab::validateType( initExpr->location, toType, symtab ); |
---|
1448 | toType = adjustExprType( toType, tenv, symtab ); |
---|
1449 | // The call to find must occur inside this loop, otherwise polymorphic return |
---|
1450 | // types are not bound to the initialization type, since return type variables are |
---|
1451 | // only open for the duration of resolving the UntypedExpr. |
---|
1452 | CandidateFinder finder{ symtab, tenv, toType }; |
---|
1453 | finder.find( initExpr->expr, ResolvMode::withAdjustment() ); |
---|
1454 | for ( CandidateRef & cand : finder.candidates ) { |
---|
1455 | if(reason.code == NotFound) reason.code = NoMatch; |
---|
1456 | |
---|
1457 | ast::TypeEnvironment env{ cand->env }; |
---|
1458 | ast::AssertionSet need( cand->need.begin(), cand->need.end() ), have; |
---|
1459 | ast::OpenVarSet open{ cand->open }; |
---|
1460 | |
---|
1461 | PRINT( |
---|
1462 | std::cerr << " @ " << toType << " " << initAlt.designation << std::endl; |
---|
1463 | ) |
---|
1464 | |
---|
1465 | // It is possible that a cast can throw away some values in a multiply-valued |
---|
1466 | // expression, e.g. cast-to-void, one value to zero. Figure out the prefix of |
---|
1467 | // the subexpression results that are cast directly. The candidate is invalid |
---|
1468 | // if it has fewer results than there are types to cast to. |
---|
1469 | int discardedValues = cand->expr->result->size() - toType->size(); |
---|
1470 | if ( discardedValues < 0 ) continue; |
---|
1471 | |
---|
1472 | // unification run for side-effects |
---|
1473 | unify( toType, cand->expr->result, env, need, have, open, symtab ); |
---|
1474 | Cost thisCost = castCost( cand->expr->result, toType, cand->expr->get_lvalue(), |
---|
1475 | symtab, env ); |
---|
1476 | |
---|
1477 | if ( thisCost != Cost::infinity ) { |
---|
1478 | // count one safe conversion for each value that is thrown away |
---|
1479 | thisCost.incSafe( discardedValues ); |
---|
1480 | CandidateRef newCand = std::make_shared<Candidate>( |
---|
1481 | new ast::InitExpr{ |
---|
1482 | initExpr->location, restructureCast( cand->expr, toType ), |
---|
1483 | initAlt.designation }, |
---|
1484 | copy( cand->env ), move( open ), move( need ), cand->cost, thisCost ); |
---|
1485 | inferParameters( newCand, matches ); |
---|
1486 | } |
---|
1487 | } |
---|
1488 | } |
---|
1489 | |
---|
1490 | // select first on argument cost, then conversion cost |
---|
1491 | CandidateList minArgCost = findMinCost( matches ); |
---|
1492 | promoteCvtCost( minArgCost ); |
---|
1493 | candidates = findMinCost( minArgCost ); |
---|
1494 | } |
---|
1495 | |
---|
1496 | void postvisit( const ast::InitExpr * ) { |
---|
1497 | assertf( false, "CandidateFinder should never see a resolved InitExpr." ); |
---|
1498 | } |
---|
1499 | |
---|
1500 | void postvisit( const ast::DeletedExpr * ) { |
---|
1501 | assertf( false, "CandidateFinder should never see a DeletedExpr." ); |
---|
1502 | } |
---|
1503 | |
---|
1504 | void postvisit( const ast::GenericExpr * ) { |
---|
1505 | assertf( false, "_Generic is not yet supported." ); |
---|
1506 | } |
---|
1507 | }; |
---|
1508 | |
---|
1509 | /// Prunes a list of candidates down to those that have the minimum conversion cost for a given |
---|
1510 | /// return type. Skips ambiguous candidates. |
---|
1511 | CandidateList pruneCandidates( CandidateList & candidates ) { |
---|
1512 | struct PruneStruct { |
---|
1513 | CandidateRef candidate; |
---|
1514 | bool ambiguous; |
---|
1515 | |
---|
1516 | PruneStruct() = default; |
---|
1517 | PruneStruct( const CandidateRef & c ) : candidate( c ), ambiguous( false ) {} |
---|
1518 | }; |
---|
1519 | |
---|
1520 | // find lowest-cost candidate for each type |
---|
1521 | std::unordered_map< std::string, PruneStruct > selected; |
---|
1522 | for ( CandidateRef & candidate : candidates ) { |
---|
1523 | std::string mangleName; |
---|
1524 | { |
---|
1525 | ast::ptr< ast::Type > newType = candidate->expr->result; |
---|
1526 | assertf(candidate->expr->result, "Result of expression %p for candidate is null", candidate->expr.get()); |
---|
1527 | candidate->env.apply( newType ); |
---|
1528 | mangleName = Mangle::mangle( newType ); |
---|
1529 | } |
---|
1530 | |
---|
1531 | auto found = selected.find( mangleName ); |
---|
1532 | if ( found != selected.end() ) { |
---|
1533 | if ( candidate->cost < found->second.candidate->cost ) { |
---|
1534 | PRINT( |
---|
1535 | std::cerr << "cost " << candidate->cost << " beats " |
---|
1536 | << found->second.candidate->cost << std::endl; |
---|
1537 | ) |
---|
1538 | |
---|
1539 | found->second = PruneStruct{ candidate }; |
---|
1540 | } else if ( candidate->cost == found->second.candidate->cost ) { |
---|
1541 | // if one of the candidates contains a deleted identifier, can pick the other, |
---|
1542 | // since deleted expressions should not be ambiguous if there is another option |
---|
1543 | // that is at least as good |
---|
1544 | if ( findDeletedExpr( candidate->expr ) ) { |
---|
1545 | // do nothing |
---|
1546 | PRINT( std::cerr << "candidate is deleted" << std::endl; ) |
---|
1547 | } else if ( findDeletedExpr( found->second.candidate->expr ) ) { |
---|
1548 | PRINT( std::cerr << "current is deleted" << std::endl; ) |
---|
1549 | found->second = PruneStruct{ candidate }; |
---|
1550 | } else { |
---|
1551 | PRINT( std::cerr << "marking ambiguous" << std::endl; ) |
---|
1552 | found->second.ambiguous = true; |
---|
1553 | } |
---|
1554 | } else { |
---|
1555 | PRINT( |
---|
1556 | std::cerr << "cost " << candidate->cost << " loses to " |
---|
1557 | << found->second.candidate->cost << std::endl; |
---|
1558 | ) |
---|
1559 | } |
---|
1560 | } else { |
---|
1561 | selected.emplace_hint( found, mangleName, candidate ); |
---|
1562 | } |
---|
1563 | } |
---|
1564 | |
---|
1565 | // report unambiguous min-cost candidates |
---|
1566 | CandidateList out; |
---|
1567 | for ( auto & target : selected ) { |
---|
1568 | if ( target.second.ambiguous ) continue; |
---|
1569 | |
---|
1570 | CandidateRef cand = target.second.candidate; |
---|
1571 | |
---|
1572 | ast::ptr< ast::Type > newResult = cand->expr->result; |
---|
1573 | cand->env.applyFree( newResult ); |
---|
1574 | cand->expr = ast::mutate_field( |
---|
1575 | cand->expr.get(), &ast::Expr::result, move( newResult ) ); |
---|
1576 | |
---|
1577 | out.emplace_back( cand ); |
---|
1578 | } |
---|
1579 | return out; |
---|
1580 | } |
---|
1581 | |
---|
1582 | } // anonymous namespace |
---|
1583 | |
---|
1584 | void CandidateFinder::find( const ast::Expr * expr, ResolvMode mode ) { |
---|
1585 | // Find alternatives for expression |
---|
1586 | ast::Pass<Finder> finder{ *this }; |
---|
1587 | expr->accept( finder ); |
---|
1588 | |
---|
1589 | if ( mode.failFast && candidates.empty() ) { |
---|
1590 | switch(finder.pass.reason.code) { |
---|
1591 | case Finder::NotFound: |
---|
1592 | { SemanticError( expr, "No alternatives for expression " ); break; } |
---|
1593 | case Finder::NoMatch: |
---|
1594 | { SemanticError( expr, "Invalid application of existing declaration(s) in expression " ); break; } |
---|
1595 | case Finder::ArgsToFew: |
---|
1596 | case Finder::ArgsToMany: |
---|
1597 | case Finder::RetsToFew: |
---|
1598 | case Finder::RetsToMany: |
---|
1599 | case Finder::NoReason: |
---|
1600 | default: |
---|
1601 | { SemanticError( expr->location, "No reasonable alternatives for expression : reasons unkown" ); } |
---|
1602 | } |
---|
1603 | } |
---|
1604 | |
---|
1605 | if ( mode.satisfyAssns || mode.prune ) { |
---|
1606 | // trim candidates to just those where the assertions are satisfiable |
---|
1607 | // - necessary pre-requisite to pruning |
---|
1608 | CandidateList satisfied; |
---|
1609 | std::vector< std::string > errors; |
---|
1610 | for ( CandidateRef & candidate : candidates ) { |
---|
1611 | satisfyAssertions( candidate, localSyms, satisfied, errors ); |
---|
1612 | } |
---|
1613 | |
---|
1614 | // fail early if none such |
---|
1615 | if ( mode.failFast && satisfied.empty() ) { |
---|
1616 | std::ostringstream stream; |
---|
1617 | stream << "No alternatives with satisfiable assertions for " << expr << "\n"; |
---|
1618 | for ( const auto& err : errors ) { |
---|
1619 | stream << err; |
---|
1620 | } |
---|
1621 | SemanticError( expr->location, stream.str() ); |
---|
1622 | } |
---|
1623 | |
---|
1624 | // reset candidates |
---|
1625 | candidates = move( satisfied ); |
---|
1626 | } |
---|
1627 | |
---|
1628 | if ( mode.prune ) { |
---|
1629 | // trim candidates to single best one |
---|
1630 | PRINT( |
---|
1631 | std::cerr << "alternatives before prune:" << std::endl; |
---|
1632 | print( std::cerr, candidates ); |
---|
1633 | ) |
---|
1634 | |
---|
1635 | CandidateList pruned = pruneCandidates( candidates ); |
---|
1636 | |
---|
1637 | if ( mode.failFast && pruned.empty() ) { |
---|
1638 | std::ostringstream stream; |
---|
1639 | CandidateList winners = findMinCost( candidates ); |
---|
1640 | stream << "Cannot choose between " << winners.size() << " alternatives for " |
---|
1641 | "expression\n"; |
---|
1642 | ast::print( stream, expr ); |
---|
1643 | stream << " Alternatives are:\n"; |
---|
1644 | print( stream, winners, 1 ); |
---|
1645 | SemanticError( expr->location, stream.str() ); |
---|
1646 | } |
---|
1647 | |
---|
1648 | auto oldsize = candidates.size(); |
---|
1649 | candidates = move( pruned ); |
---|
1650 | |
---|
1651 | PRINT( |
---|
1652 | std::cerr << "there are " << oldsize << " alternatives before elimination" << std::endl; |
---|
1653 | ) |
---|
1654 | PRINT( |
---|
1655 | std::cerr << "there are " << candidates.size() << " alternatives after elimination" |
---|
1656 | << std::endl; |
---|
1657 | ) |
---|
1658 | } |
---|
1659 | |
---|
1660 | // adjust types after pruning so that types substituted by pruneAlternatives are correctly |
---|
1661 | // adjusted |
---|
1662 | if ( mode.adjust ) { |
---|
1663 | for ( CandidateRef & r : candidates ) { |
---|
1664 | r->expr = ast::mutate_field( |
---|
1665 | r->expr.get(), &ast::Expr::result, |
---|
1666 | adjustExprType( r->expr->result, r->env, localSyms ) ); |
---|
1667 | } |
---|
1668 | } |
---|
1669 | |
---|
1670 | // Central location to handle gcc extension keyword, etc. for all expressions |
---|
1671 | for ( CandidateRef & r : candidates ) { |
---|
1672 | if ( r->expr->extension != expr->extension ) { |
---|
1673 | r->expr.get_and_mutate()->extension = expr->extension; |
---|
1674 | } |
---|
1675 | } |
---|
1676 | } |
---|
1677 | |
---|
1678 | std::vector< CandidateFinder > CandidateFinder::findSubExprs( |
---|
1679 | const std::vector< ast::ptr< ast::Expr > > & xs |
---|
1680 | ) { |
---|
1681 | std::vector< CandidateFinder > out; |
---|
1682 | |
---|
1683 | for ( const auto & x : xs ) { |
---|
1684 | out.emplace_back( localSyms, env ); |
---|
1685 | out.back().find( x, ResolvMode::withAdjustment() ); |
---|
1686 | |
---|
1687 | PRINT( |
---|
1688 | std::cerr << "findSubExprs" << std::endl; |
---|
1689 | print( std::cerr, out.back().candidates ); |
---|
1690 | ) |
---|
1691 | } |
---|
1692 | |
---|
1693 | return out; |
---|
1694 | } |
---|
1695 | |
---|
1696 | } // namespace ResolvExpr |
---|
1697 | |
---|
1698 | // Local Variables: // |
---|
1699 | // tab-width: 4 // |
---|
1700 | // mode: c++ // |
---|
1701 | // compile-command: "make install" // |
---|
1702 | // End: // |
---|