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 | // GenInit.cc -- Generate initializers, and other stuff. |
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8 | // |
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9 | // Author : Rob Schluntz |
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10 | // Created On : Mon May 18 07:44:20 2015 |
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11 | // Last Modified By : Andrew Beach |
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12 | // Last Modified On : Mon Oct 25 13:53:00 2021 |
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13 | // Update Count : 186 |
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14 | // |
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15 | #include "GenInit.h" |
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16 | |
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17 | #include <stddef.h> // for NULL |
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18 | #include <algorithm> // for any_of |
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19 | #include <cassert> // for assert, strict_dynamic_cast, assertf |
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20 | #include <deque> |
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21 | #include <iterator> // for back_inserter, inserter, back_inse... |
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22 | #include <list> // for _List_iterator, list |
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23 | |
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24 | #include "AST/Decl.hpp" |
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25 | #include "AST/Init.hpp" |
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26 | #include "AST/Pass.hpp" |
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27 | #include "AST/Node.hpp" |
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28 | #include "AST/Stmt.hpp" |
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29 | #include "CompilationState.hpp" |
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30 | #include "CodeGen/OperatorTable.h" |
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31 | #include "Common/SemanticError.h" // for SemanticError |
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32 | #include "Common/ToString.hpp" // for toCString |
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33 | #include "Common/UniqueName.h" // for UniqueName |
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34 | #include "Common/utility.h" // for ValueGuard, maybeClone |
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35 | #include "GenPoly/GenPoly.h" // for getFunctionType, isPolyType |
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36 | #include "GenPoly/ScopedSet.h" // for ScopedSet, ScopedSet<>::const_iter... |
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37 | #include "InitTweak.h" // for isConstExpr, InitExpander, checkIn... |
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38 | #include "ResolvExpr/Resolver.h" |
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39 | #include "SymTab/GenImplicitCall.hpp" // for genImplicitCall |
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40 | #include "SymTab/Mangler.h" // for Mangler |
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41 | #include "Tuples/Tuples.h" // for maybeImpure |
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42 | #include "Validate/FindSpecialDecls.h" // for SizeType |
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43 | |
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44 | namespace InitTweak { |
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45 | |
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46 | namespace { |
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47 | |
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48 | // Outer pass finds declarations, for their type could wrap a type that needs hoisting |
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49 | struct HoistArrayDimension_NoResolve final : |
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50 | public ast::WithDeclsToAdd<>, public ast::WithShortCircuiting, |
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51 | public ast::WithGuards, public ast::WithConstTranslationUnit, |
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52 | public ast::WithVisitorRef<HoistArrayDimension_NoResolve>, |
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53 | public ast::WithSymbolTableX<ast::SymbolTable::ErrorDetection::IgnoreErrors> { |
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54 | |
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55 | // Inner pass looks within a type, for a part that depends on an expression |
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56 | struct HoistDimsFromTypes final : |
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57 | public ast::WithShortCircuiting, public ast::WithGuards { |
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58 | |
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59 | HoistArrayDimension_NoResolve * outer; |
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60 | HoistDimsFromTypes( HoistArrayDimension_NoResolve * outer ) : outer(outer) {} |
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61 | |
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62 | // Only intended for visiting through types. |
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63 | // Tolerate, and short-circuit at, the dimension expression of an array type. |
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64 | // (We'll operate on the dimension expression of an array type directly |
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65 | // from the parent type, not by visiting through it) |
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66 | // Look inside type exprs. |
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67 | void previsit( const ast::Node * ) { |
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68 | assert( false && "unsupported node type" ); |
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69 | }; |
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70 | const ast::Expr * allowedExpr = nullptr; |
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71 | void previsit( const ast::Type * ) { |
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72 | GuardValue( allowedExpr ) = nullptr; |
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73 | } |
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74 | void previsit( const ast::ArrayType * t ) { |
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75 | GuardValue( allowedExpr ) = t->dimension.get(); |
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76 | } |
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77 | void previsit( const ast::PointerType * t ) { |
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78 | GuardValue( allowedExpr ) = t->dimension.get(); |
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79 | } |
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80 | void previsit( const ast::TypeofType * t ) { |
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81 | GuardValue( allowedExpr ) = t->expr.get(); |
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82 | } |
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83 | void previsit( const ast::Expr * e ) { |
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84 | assert( e == allowedExpr && |
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85 | "only expecting to visit exprs that are dimension exprs or typeof(-) inner exprs" ); |
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86 | |
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87 | // Skip the tolerated expressions |
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88 | visit_children = false; |
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89 | } |
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90 | void previsit( const ast::TypeExpr * ) {} |
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91 | |
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92 | const ast::Type * postvisit( |
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93 | const ast::ArrayType * arrayType ) { |
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94 | static UniqueName dimensionName( "_array_dim" ); |
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95 | |
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96 | if ( nullptr == arrayType->dimension ) { // if no dimension is given, don't presume to invent one |
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97 | return arrayType; |
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98 | } |
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99 | |
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100 | // find size_t; use it as the type for a dim expr |
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101 | ast::ptr<ast::Type> dimType = outer->transUnit().global.sizeType; |
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102 | assert( dimType ); |
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103 | add_qualifiers( dimType, ast::CV::Qualifiers( ast::CV::Const ) ); |
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104 | |
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105 | // Special-case handling: leave the user's dimension expression alone |
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106 | // - requires the user to have followed a careful convention |
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107 | // - may apply to extremely simple applications, but only as windfall |
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108 | // - users of advanced applications will be following the convention on purpose |
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109 | // - CFA maintainers must protect the criteria against leaving too much alone |
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110 | |
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111 | // Actual leave-alone cases following are conservative approximations of "cannot vary" |
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112 | |
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113 | // Leave alone: literals and enum constants |
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114 | if ( dynamic_cast< const ast::ConstantExpr * >( arrayType->dimension.get() ) ) { |
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115 | return arrayType; |
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116 | } |
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117 | |
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118 | // Leave alone: direct use of an object declared to be const |
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119 | const ast::NameExpr * dimn = dynamic_cast< const ast::NameExpr * >( arrayType->dimension.get() ); |
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120 | if ( dimn ) { |
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121 | std::vector<ast::SymbolTable::IdData> dimnDefs = outer->symtab.lookupId( dimn->name ); |
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122 | if ( dimnDefs.size() == 1 ) { |
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123 | const ast::DeclWithType * dimnDef = dimnDefs[0].id.get(); |
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124 | assert( dimnDef && "symbol table binds a name to nothing" ); |
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125 | const ast::ObjectDecl * dimOb = dynamic_cast< const ast::ObjectDecl * >( dimnDef ); |
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126 | if( dimOb ) { |
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127 | const ast::Type * dimTy = dimOb->type.get(); |
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128 | assert( dimTy && "object declaration bearing no type" ); |
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129 | // must not hoist some: size_t |
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130 | // must hoist all: pointers and references |
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131 | // the analysis is conservative; BasicType is a simple approximation |
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132 | if ( dynamic_cast< const ast::BasicType * >( dimTy ) || |
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133 | dynamic_cast< const ast::SueInstType<ast::EnumDecl> * >( dimTy ) ) { |
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134 | if ( dimTy->is_const() ) { |
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135 | // The dimension is certainly re-evaluable, giving the same answer each time. |
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136 | // Our user might be hoping to write the array type in multiple places, having them unify. |
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137 | // Leave the type alone. |
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138 | |
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139 | // We believe the new criterion leaves less alone than the old criterion. |
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140 | // Thus, the old criterion should have left the current case alone. |
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141 | // Catch cases that weren't thought through. |
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142 | assert( !Tuples::maybeImpure( arrayType->dimension ) ); |
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143 | |
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144 | return arrayType; |
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145 | } |
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146 | }; |
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147 | } |
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148 | } |
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149 | } |
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150 | |
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151 | // Leave alone: any sizeof expression (answer cannot vary during current lexical scope) |
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152 | const ast::SizeofExpr * sz = dynamic_cast< const ast::SizeofExpr * >( arrayType->dimension.get() ); |
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153 | if ( sz ) { |
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154 | return arrayType; |
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155 | } |
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156 | |
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157 | // General-case handling: change the array-type's dim expr (hoist the user-given content out of the type) |
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158 | // - always safe |
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159 | // - user-unnoticeable in common applications (benign noise in -CFA output) |
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160 | // - may annoy a responsible user of advanced applications (but they can work around) |
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161 | // - protects against misusing advanced features |
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162 | // |
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163 | // The hoist, by example, is: |
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164 | // FROM USER: float a[ rand() ]; |
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165 | // TO GCC: const size_t __len_of_a = rand(); float a[ __len_of_a ]; |
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166 | |
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167 | ast::ObjectDecl * arrayDimension = new ast::ObjectDecl( |
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168 | arrayType->dimension->location, |
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169 | dimensionName.newName(), |
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170 | dimType, |
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171 | new ast::SingleInit( |
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172 | arrayType->dimension->location, |
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173 | arrayType->dimension |
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174 | ) |
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175 | ); |
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176 | |
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177 | ast::ArrayType * mutType = ast::mutate( arrayType ); |
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178 | mutType->dimension = new ast::VariableExpr( |
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179 | arrayDimension->location, arrayDimension ); |
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180 | outer->declsToAddBefore.push_back( arrayDimension ); |
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181 | |
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182 | return mutType; |
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183 | } // postvisit( const ast::ArrayType * ) |
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184 | }; // struct HoistDimsFromTypes |
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185 | |
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186 | ast::Storage::Classes storageClasses; |
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187 | void previsit( |
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188 | const ast::ObjectDecl * decl ) { |
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189 | GuardValue( storageClasses ) = decl->storage; |
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190 | } |
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191 | |
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192 | const ast::DeclWithType * postvisit( |
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193 | const ast::ObjectDecl * objectDecl ) { |
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194 | |
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195 | if ( !isInFunction() || storageClasses.is_static ) { |
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196 | return objectDecl; |
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197 | } |
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198 | |
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199 | const ast::Type * mid = objectDecl->type; |
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200 | |
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201 | ast::Pass<HoistDimsFromTypes> hoist{this}; |
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202 | const ast::Type * result = mid->accept( hoist ); |
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203 | |
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204 | return mutate_field( objectDecl, &ast::ObjectDecl::type, result ); |
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205 | } |
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206 | }; |
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207 | |
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208 | struct ReturnFixer final : |
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209 | public ast::WithStmtsToAdd<>, ast::WithGuards, ast::WithShortCircuiting { |
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210 | void previsit( const ast::FunctionDecl * decl ); |
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211 | const ast::ReturnStmt * previsit( const ast::ReturnStmt * stmt ); |
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212 | private: |
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213 | const ast::FunctionDecl * funcDecl = nullptr; |
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214 | }; |
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215 | |
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216 | void ReturnFixer::previsit( const ast::FunctionDecl * decl ) { |
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217 | if (decl->linkage == ast::Linkage::Intrinsic) visit_children = false; |
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218 | GuardValue( funcDecl ) = decl; |
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219 | } |
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220 | |
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221 | const ast::ReturnStmt * ReturnFixer::previsit( |
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222 | const ast::ReturnStmt * stmt ) { |
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223 | auto & returns = funcDecl->returns; |
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224 | assert( returns.size() < 2 ); |
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225 | // Hands off if the function returns a reference. |
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226 | // Don't allocate a temporary if the address is returned. |
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227 | if ( stmt->expr && 1 == returns.size() ) { |
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228 | ast::ptr<ast::DeclWithType> retDecl = returns.front(); |
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229 | if ( isConstructable( retDecl->get_type() ) ) { |
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230 | // Explicitly construct the return value using the return |
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231 | // expression and the retVal object. |
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232 | assertf( "" != retDecl->name, |
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233 | "Function %s has unnamed return value.\n", |
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234 | funcDecl->name.c_str() ); |
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235 | |
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236 | auto retVal = retDecl.strict_as<ast::ObjectDecl>(); |
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237 | if ( auto varExpr = stmt->expr.as<ast::VariableExpr>() ) { |
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238 | // Check if the return statement is already set up. |
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239 | if ( varExpr->var == retVal ) return stmt; |
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240 | } |
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241 | const ast::Stmt * ctorStmt = genCtorDtor( |
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242 | retVal->location, "?{}", retVal, stmt->expr ); |
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243 | assertf( ctorStmt, |
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244 | "ReturnFixer: genCtorDtor returned nullptr: %s / %s", |
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245 | toString( retVal ).c_str(), |
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246 | toString( stmt->expr ).c_str() ); |
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247 | stmtsToAddBefore.push_back( ctorStmt ); |
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248 | |
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249 | // Return the retVal object. |
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250 | ast::ReturnStmt * mutStmt = ast::mutate( stmt ); |
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251 | mutStmt->expr = new ast::VariableExpr( |
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252 | stmt->location, retDecl ); |
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253 | return mutStmt; |
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254 | } |
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255 | } |
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256 | return stmt; |
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257 | } |
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258 | |
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259 | } // namespace |
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260 | |
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261 | void genInit( ast::TranslationUnit & transUnit ) { |
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262 | ast::Pass<HoistArrayDimension_NoResolve>::run( transUnit ); |
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263 | ast::Pass<ReturnFixer>::run( transUnit ); |
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264 | } |
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265 | |
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266 | void fixReturnStatements( ast::TranslationUnit & transUnit ) { |
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267 | ast::Pass<ReturnFixer>::run( transUnit ); |
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268 | } |
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269 | |
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270 | bool ManagedTypes::isManaged( const ast::Type * type ) const { |
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271 | // references are never constructed |
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272 | if ( dynamic_cast< const ast::ReferenceType * >( type ) ) return false; |
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273 | if ( auto tupleType = dynamic_cast< const ast::TupleType * > ( type ) ) { |
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274 | // tuple is also managed if any of its components are managed |
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275 | for (auto & component : tupleType->types) { |
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276 | if (isManaged(component)) return true; |
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277 | } |
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278 | } |
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279 | // need to clear and reset qualifiers when determining if a type is managed |
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280 | // ValueGuard< Type::Qualifiers > qualifiers( type->get_qualifiers() ); |
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281 | auto tmp = shallowCopy(type); |
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282 | tmp->qualifiers = {}; |
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283 | // delete tmp at return |
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284 | ast::ptr<ast::Type> guard = tmp; |
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285 | // a type is managed if it appears in the map of known managed types, or if it contains any polymorphism (is a type variable or generic type containing a type variable) |
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286 | return managedTypes.find( Mangle::mangle( tmp, {Mangle::NoOverrideable | Mangle::NoGenericParams | Mangle::Type} ) ) != managedTypes.end() || GenPoly::isPolyType( tmp ); |
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287 | } |
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288 | |
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289 | bool ManagedTypes::isManaged( const ast::ObjectDecl * objDecl ) const { |
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290 | const ast::Type * type = objDecl->type; |
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291 | while ( auto at = dynamic_cast< const ast::ArrayType * >( type ) ) { |
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292 | // must always construct VLAs with an initializer, since this is an error in C |
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293 | if ( at->isVarLen && objDecl->init ) return true; |
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294 | type = at->base; |
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295 | } |
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296 | return isManaged( type ); |
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297 | } |
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298 | |
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299 | void ManagedTypes::handleDWT( const ast::DeclWithType * dwt ) { |
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300 | // if this function is a user-defined constructor or destructor, mark down the type as "managed" |
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301 | if ( ! dwt->linkage.is_overrideable && CodeGen::isCtorDtor( dwt->name ) ) { |
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302 | auto & params = GenPoly::getFunctionType( dwt->get_type())->params; |
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303 | assert( ! params.empty() ); |
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304 | // Type * type = InitTweak::getPointerBase( params.front() ); |
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305 | // assert( type ); |
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306 | managedTypes.insert( Mangle::mangle( params.front(), {Mangle::NoOverrideable | Mangle::NoGenericParams | Mangle::Type} ) ); |
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307 | } |
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308 | } |
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309 | |
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310 | void ManagedTypes::handleStruct( const ast::StructDecl * aggregateDecl ) { |
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311 | // don't construct members, but need to take note if there is a managed member, |
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312 | // because that means that this type is also managed |
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313 | for ( auto & member : aggregateDecl->members ) { |
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314 | if ( auto field = member.as<ast::ObjectDecl>() ) { |
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315 | if ( isManaged( field ) ) { |
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316 | // generic parameters should not play a role in determining whether a generic type is constructed - construct all generic types, so that |
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317 | // polymorphic constructors make generic types managed types |
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318 | ast::StructInstType inst( aggregateDecl ); |
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319 | managedTypes.insert( Mangle::mangle( &inst, {Mangle::NoOverrideable | Mangle::NoGenericParams | Mangle::Type} ) ); |
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320 | break; |
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321 | } |
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322 | } |
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323 | } |
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324 | } |
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325 | |
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326 | void ManagedTypes::beginScope() { managedTypes.beginScope(); } |
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327 | void ManagedTypes::endScope() { managedTypes.endScope(); } |
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328 | |
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329 | const ast::Stmt * genCtorDtor( const CodeLocation & loc, const std::string & fname, const ast::ObjectDecl * objDecl, const ast::Expr * arg ) { |
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330 | assertf(objDecl, "genCtorDtor passed null objDecl"); |
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331 | InitExpander srcParam(arg); |
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332 | return SymTab::genImplicitCall(srcParam, new ast::VariableExpr(loc, objDecl), loc, fname, objDecl); |
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333 | } |
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334 | |
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335 | ast::ConstructorInit * genCtorInit( const CodeLocation & loc, const ast::ObjectDecl * objDecl ) { |
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336 | // call into genImplicitCall from Autogen.h to generate calls to ctor/dtor for each |
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337 | // constructable object |
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338 | InitExpander srcParam{ objDecl->init }, nullParam{ (const ast::Init *)nullptr }; |
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339 | ast::ptr< ast::Expr > dstParam = new ast::VariableExpr(loc, objDecl); |
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340 | |
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341 | ast::ptr< ast::Stmt > ctor = SymTab::genImplicitCall( |
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342 | srcParam, dstParam, loc, "?{}", objDecl ); |
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343 | ast::ptr< ast::Stmt > dtor = SymTab::genImplicitCall( |
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344 | nullParam, dstParam, loc, "^?{}", objDecl, |
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345 | SymTab::LoopBackward ); |
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346 | |
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347 | // check that either both ctor and dtor are present, or neither |
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348 | assert( (bool)ctor == (bool)dtor ); |
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349 | |
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350 | if ( ctor ) { |
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351 | // need to remember init expression, in case no ctors exist. If ctor does exist, want to |
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352 | // use ctor expression instead of init. |
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353 | ctor.strict_as< ast::ImplicitCtorDtorStmt >(); |
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354 | dtor.strict_as< ast::ImplicitCtorDtorStmt >(); |
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355 | |
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356 | return new ast::ConstructorInit{ loc, ctor, dtor, objDecl->init }; |
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357 | } |
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358 | |
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359 | return nullptr; |
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360 | } |
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361 | |
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362 | } // namespace InitTweak |
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363 | |
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364 | // Local Variables: // |
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365 | // tab-width: 4 // |
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366 | // mode: c++ // |
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367 | // compile-command: "make install" // |
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368 | // End: // |
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