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 | // TupleAssignment.cc -- |
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8 | // |
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9 | // Author : Rodolfo G. Esteves |
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10 | // Created On : Mon May 18 07:44:20 2015 |
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11 | // Last Modified By : Peter A. Buhr |
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12 | // Last Modified On : Wed Jun 21 17:35:04 2017 |
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13 | // Update Count : 19 |
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14 | // |
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15 | |
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16 | #include <stddef.h> // for size_t |
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17 | #include <cassert> // for assert |
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18 | #include <list> // for list |
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19 | |
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20 | #include "Common/PassVisitor.h" // for PassVisitor, WithDeclsToAdd, WithGu... |
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21 | #include "Common/ScopedMap.h" // for ScopedMap |
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22 | #include "Common/utility.h" // for CodeLocation |
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23 | #include "InitTweak/InitTweak.h" // for getFunction |
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24 | #include "Parser/LinkageSpec.h" // for Spec, C, Intrinsic |
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25 | #include "SynTree/Constant.h" // for Constant |
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26 | #include "SynTree/Declaration.h" // for StructDecl, DeclarationWithType |
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27 | #include "SynTree/Expression.h" // for UntypedMemberExpr, Expression, Uniq... |
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28 | #include "SynTree/Label.h" // for operator==, Label |
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29 | #include "SynTree/Mutator.h" // for Mutator |
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30 | #include "SynTree/Type.h" // for Type, Type::Qualifiers, TupleType |
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31 | #include "SynTree/Visitor.h" // for Visitor |
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32 | |
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33 | class CompoundStmt; |
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34 | class TypeSubstitution; |
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35 | |
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36 | namespace Tuples { |
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37 | namespace { |
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38 | struct MemberTupleExpander final : public WithShortCircuiting, public WithVisitorRef<MemberTupleExpander> { |
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39 | void premutate( UntypedMemberExpr * ) { visit_children = false; } |
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40 | Expression * postmutate( UntypedMemberExpr * memberExpr ); |
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41 | }; |
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42 | |
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43 | struct UniqueExprExpander final : public WithDeclsToAdd { |
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44 | Expression * postmutate( UniqueExpr * unqExpr ); |
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45 | |
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46 | std::map< int, Expression * > decls; // not vector, because order added may not be increasing order |
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47 | |
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48 | ~UniqueExprExpander() { |
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49 | for ( std::pair<const int, Expression *> & p : decls ) { |
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50 | delete p.second; |
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51 | } |
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52 | } |
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53 | }; |
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54 | |
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55 | struct TupleAssignExpander { |
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56 | Expression * postmutate( TupleAssignExpr * tupleExpr ); |
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57 | }; |
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58 | |
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59 | struct TupleTypeReplacer : public WithDeclsToAdd, public WithGuards, public WithTypeSubstitution { |
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60 | Type * postmutate( TupleType * tupleType ); |
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61 | |
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62 | void premutate( CompoundStmt * ) { |
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63 | GuardScope( typeMap ); |
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64 | } |
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65 | private: |
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66 | ScopedMap< int, StructDecl * > typeMap; |
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67 | }; |
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68 | |
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69 | struct TupleIndexExpander { |
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70 | Expression * postmutate( TupleIndexExpr * tupleExpr ); |
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71 | }; |
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72 | |
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73 | struct TupleExprExpander final { |
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74 | Expression * postmutate( TupleExpr * tupleExpr ); |
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75 | }; |
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76 | } |
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77 | |
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78 | void expandMemberTuples( std::list< Declaration * > & translationUnit ) { |
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79 | PassVisitor<MemberTupleExpander> expander; |
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80 | mutateAll( translationUnit, expander ); |
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81 | } |
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82 | |
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83 | void expandUniqueExpr( std::list< Declaration * > & translationUnit ) { |
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84 | PassVisitor<UniqueExprExpander> unqExpander; |
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85 | mutateAll( translationUnit, unqExpander ); |
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86 | } |
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87 | |
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88 | void expandTuples( std::list< Declaration * > & translationUnit ) { |
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89 | PassVisitor<TupleAssignExpander> assnExpander; |
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90 | mutateAll( translationUnit, assnExpander ); |
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91 | |
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92 | PassVisitor<TupleTypeReplacer> replacer; |
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93 | mutateAll( translationUnit, replacer ); |
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94 | |
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95 | PassVisitor<TupleIndexExpander> idxExpander; |
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96 | mutateAll( translationUnit, idxExpander ); |
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97 | |
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98 | PassVisitor<TupleExprExpander> exprExpander; |
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99 | mutateAll( translationUnit, exprExpander ); |
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100 | } |
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101 | |
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102 | namespace { |
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103 | /// given a expression representing the member and an expression representing the aggregate, |
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104 | /// reconstructs a flattened UntypedMemberExpr with the right precedence |
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105 | Expression * reconstructMemberExpr( Expression * member, Expression * aggr, CodeLocation & loc ) { |
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106 | if ( UntypedMemberExpr * memberExpr = dynamic_cast< UntypedMemberExpr * >( member ) ) { |
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107 | // construct a new UntypedMemberExpr with the correct structure , and recursively |
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108 | // expand that member expression. |
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109 | PassVisitor<MemberTupleExpander> expander; |
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110 | UntypedMemberExpr * inner = new UntypedMemberExpr( memberExpr->aggregate, aggr->clone() ); |
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111 | UntypedMemberExpr * newMemberExpr = new UntypedMemberExpr( memberExpr->member, inner ); |
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112 | inner->location = newMemberExpr->location = loc; |
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113 | memberExpr->member = nullptr; |
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114 | memberExpr->aggregate = nullptr; |
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115 | delete memberExpr; |
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116 | return newMemberExpr->acceptMutator( expander ); |
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117 | } else { |
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118 | // not a member expression, so there is nothing to do but attach and return |
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119 | UntypedMemberExpr * newMemberExpr = new UntypedMemberExpr( member, aggr->clone() ); |
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120 | newMemberExpr->location = loc; |
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121 | return newMemberExpr; |
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122 | } |
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123 | } |
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124 | } |
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125 | |
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126 | Expression * MemberTupleExpander::postmutate( UntypedMemberExpr * memberExpr ) { |
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127 | if ( UntypedTupleExpr * tupleExpr = dynamic_cast< UntypedTupleExpr * > ( memberExpr->member ) ) { |
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128 | Expression * aggr = memberExpr->aggregate->clone()->acceptMutator( *visitor ); |
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129 | // aggregate expressions which might be impure must be wrapped in unique expressions |
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130 | // xxx - if there's a member-tuple expression nested in the aggregate, this currently generates the wrong code if a UniqueExpr is not used, and it's purely an optimization to remove the UniqueExpr |
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131 | // if ( Tuples::maybeImpureIgnoreUnique( memberExpr->get_aggregate() ) ) aggr = new UniqueExpr( aggr ); |
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132 | aggr = new UniqueExpr( aggr ); |
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133 | for ( Expression *& expr : tupleExpr->exprs ) { |
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134 | expr = reconstructMemberExpr( expr, aggr, memberExpr->location ); |
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135 | expr->location = memberExpr->location; |
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136 | } |
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137 | delete aggr; |
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138 | tupleExpr->location = memberExpr->location; |
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139 | return tupleExpr; |
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140 | } else { |
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141 | // there may be a tuple expr buried in the aggregate |
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142 | // xxx - this is a memory leak |
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143 | UntypedMemberExpr * newMemberExpr = new UntypedMemberExpr( memberExpr->member->clone(), memberExpr->aggregate->acceptMutator( *visitor ) ); |
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144 | newMemberExpr->location = memberExpr->location; |
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145 | return newMemberExpr; |
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146 | } |
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147 | } |
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148 | |
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149 | Expression * UniqueExprExpander::postmutate( UniqueExpr * unqExpr ) { |
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150 | const int id = unqExpr->get_id(); |
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151 | |
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152 | // on first time visiting a unique expr with a particular ID, generate the expression that replaces all UniqueExprs with that ID, |
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153 | // and lookup on subsequent hits. This ensures that all unique exprs with the same ID reference the same variable. |
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154 | if ( ! decls.count( id ) ) { |
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155 | Expression * assignUnq; |
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156 | Expression * var = unqExpr->get_var(); |
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157 | if ( unqExpr->get_object() ) { |
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158 | // an object was generated to represent this unique expression -- it should be added to the list of declarations now |
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159 | declsToAddBefore.push_back( unqExpr->get_object() ); |
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160 | unqExpr->set_object( nullptr ); |
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161 | // steal the expr from the unqExpr |
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162 | assignUnq = UntypedExpr::createAssign( unqExpr->get_var()->clone(), unqExpr->get_expr() ); |
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163 | unqExpr->set_expr( nullptr ); |
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164 | } else { |
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165 | // steal the already generated assignment to var from the unqExpr - this has been generated by FixInit |
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166 | Expression * expr = unqExpr->get_expr(); |
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167 | CommaExpr * commaExpr = strict_dynamic_cast< CommaExpr * >( expr ); |
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168 | assignUnq = commaExpr->get_arg1(); |
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169 | commaExpr->set_arg1( nullptr ); |
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170 | } |
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171 | ObjectDecl * finished = new ObjectDecl( toString( "_unq", id, "_finished_" ), Type::StorageClasses(), LinkageSpec::Cforall, nullptr, new BasicType( Type::Qualifiers(), BasicType::Bool ), |
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172 | new SingleInit( new ConstantExpr( Constant::from_int( 0 ) ) ) ); |
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173 | declsToAddBefore.push_back( finished ); |
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174 | // (finished ? _unq_expr_N : (_unq_expr_N = <unqExpr->get_expr()>, finished = 1, _unq_expr_N)) |
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175 | // This pattern ensures that each unique expression is evaluated once, regardless of evaluation order of the generated C code. |
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176 | Expression * assignFinished = UntypedExpr::createAssign( new VariableExpr(finished), new ConstantExpr( Constant::from_int( 1 ) ) ); |
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177 | ConditionalExpr * condExpr = new ConditionalExpr( new VariableExpr( finished ), var->clone(), |
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178 | new CommaExpr( new CommaExpr( assignUnq, assignFinished ), var->clone() ) ); |
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179 | condExpr->set_result( var->get_result()->clone() ); |
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180 | condExpr->set_env( maybeClone( unqExpr->get_env() ) ); |
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181 | decls[id] = condExpr; |
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182 | } |
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183 | delete unqExpr; |
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184 | return decls[id]->clone(); |
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185 | } |
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186 | |
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187 | Expression * TupleAssignExpander::postmutate( TupleAssignExpr * assnExpr ) { |
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188 | StmtExpr * ret = assnExpr->get_stmtExpr(); |
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189 | assnExpr->set_stmtExpr( nullptr ); |
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190 | // move env to StmtExpr |
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191 | ret->set_env( assnExpr->get_env() ); |
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192 | assnExpr->set_env( nullptr ); |
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193 | delete assnExpr; |
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194 | return ret; |
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195 | } |
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196 | |
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197 | Type * TupleTypeReplacer::postmutate( TupleType * tupleType ) { |
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198 | unsigned tupleSize = tupleType->size(); |
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199 | if ( ! typeMap.count( tupleSize ) ) { |
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200 | // generate struct type to replace tuple type based on the number of components in the tuple |
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201 | StructDecl * decl = new StructDecl( toString( "_tuple", tupleSize, "_" ) ); |
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202 | decl->location = tupleType->location; |
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203 | decl->set_body( true ); |
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204 | for ( size_t i = 0; i < tupleSize; ++i ) { |
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205 | TypeDecl * tyParam = new TypeDecl( toString( "tuple_param_", tupleSize, "_", i ), Type::StorageClasses(), nullptr, TypeDecl::Dtype, true ); |
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206 | decl->get_members().push_back( new ObjectDecl( toString("field_", i ), Type::StorageClasses(), LinkageSpec::C, nullptr, new TypeInstType( Type::Qualifiers(), tyParam->get_name(), tyParam ), nullptr ) ); |
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207 | decl->get_parameters().push_back( tyParam ); |
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208 | } |
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209 | if ( tupleSize == 0 ) { |
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210 | // empty structs are not standard C. Add a dummy field to empty tuples to silence warnings when a compound literal Tuple0 is created. |
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211 | decl->get_members().push_back( new ObjectDecl( "dummy", Type::StorageClasses(), LinkageSpec::C, nullptr, new BasicType( Type::Qualifiers(), BasicType::SignedInt ), nullptr ) ); |
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212 | } |
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213 | typeMap[tupleSize] = decl; |
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214 | declsToAddBefore.push_back( decl ); |
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215 | } |
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216 | Type::Qualifiers qualifiers = tupleType->get_qualifiers(); |
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217 | |
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218 | StructDecl * decl = typeMap[tupleSize]; |
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219 | StructInstType * newType = new StructInstType( qualifiers, decl ); |
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220 | for ( auto p : group_iterate( tupleType->get_types(), decl->get_parameters() ) ) { |
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221 | Type * t = std::get<0>(p); |
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222 | newType->get_parameters().push_back( new TypeExpr( t->clone() ) ); |
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223 | } |
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224 | delete tupleType; |
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225 | return newType; |
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226 | } |
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227 | |
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228 | Expression * TupleIndexExpander::postmutate( TupleIndexExpr * tupleExpr ) { |
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229 | Expression * tuple = tupleExpr->tuple; |
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230 | assert( tuple ); |
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231 | tupleExpr->tuple = nullptr; |
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232 | unsigned int idx = tupleExpr->index; |
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233 | TypeSubstitution * env = tupleExpr->env; |
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234 | tupleExpr->env = nullptr; |
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235 | delete tupleExpr; |
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236 | |
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237 | StructInstType * type = strict_dynamic_cast< StructInstType * >( tuple->result ); |
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238 | StructDecl * structDecl = type->baseStruct; |
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239 | assert( structDecl->members.size() > idx ); |
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240 | Declaration * member = *std::next(structDecl->members.begin(), idx); |
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241 | MemberExpr * memExpr = new MemberExpr( strict_dynamic_cast< DeclarationWithType * >( member ), tuple ); |
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242 | memExpr->env = env; |
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243 | return memExpr; |
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244 | } |
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245 | |
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246 | Expression * replaceTupleExpr( Type * result, const std::list< Expression * > & exprs, TypeSubstitution * env ) { |
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247 | if ( result->isVoid() ) { |
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248 | // void result - don't need to produce a value for cascading - just output a chain of comma exprs |
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249 | assert( ! exprs.empty() ); |
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250 | std::list< Expression * >::const_iterator iter = exprs.begin(); |
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251 | Expression * expr = new CastExpr( *iter++ ); |
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252 | for ( ; iter != exprs.end(); ++iter ) { |
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253 | expr = new CommaExpr( expr, new CastExpr( *iter ) ); |
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254 | } |
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255 | expr->set_env( env ); |
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256 | return expr; |
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257 | } else { |
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258 | // typed tuple expression - produce a compound literal which performs each of the expressions |
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259 | // as a distinct part of its initializer - the produced compound literal may be used as part of |
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260 | // another expression |
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261 | std::list< Initializer * > inits; |
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262 | for ( Expression * expr : exprs ) { |
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263 | inits.push_back( new SingleInit( expr ) ); |
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264 | } |
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265 | Expression * expr = new CompoundLiteralExpr( result, new ListInit( inits ) ); |
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266 | expr->set_env( env ); |
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267 | return expr; |
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268 | } |
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269 | } |
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270 | |
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271 | Expression * TupleExprExpander::postmutate( TupleExpr * tupleExpr ) { |
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272 | Type * result = tupleExpr->get_result(); |
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273 | std::list< Expression * > exprs = tupleExpr->get_exprs(); |
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274 | assert( result ); |
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275 | TypeSubstitution * env = tupleExpr->get_env(); |
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276 | |
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277 | // remove data from shell and delete it |
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278 | tupleExpr->set_result( nullptr ); |
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279 | tupleExpr->get_exprs().clear(); |
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280 | tupleExpr->set_env( nullptr ); |
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281 | delete tupleExpr; |
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282 | |
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283 | return replaceTupleExpr( result, exprs, env ); |
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284 | } |
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285 | |
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286 | Type * makeTupleType( const std::list< Expression * > & exprs ) { |
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287 | // produce the TupleType which aggregates the types of the exprs |
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288 | std::list< Type * > types; |
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289 | Type::Qualifiers qualifiers( Type::Const | Type::Volatile | Type::Restrict | Type::Lvalue | Type::Atomic | Type::Mutex ); |
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290 | for ( Expression * expr : exprs ) { |
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291 | assert( expr->get_result() ); |
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292 | if ( expr->get_result()->isVoid() ) { |
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293 | // if the type of any expr is void, the type of the entire tuple is void |
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294 | return new VoidType( Type::Qualifiers() ); |
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295 | } |
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296 | Type * type = expr->get_result()->clone(); |
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297 | types.push_back( type ); |
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298 | // the qualifiers on the tuple type are the qualifiers that exist on all component types |
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299 | qualifiers &= type->get_qualifiers(); |
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300 | } // for |
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301 | if ( exprs.empty() ) qualifiers = Type::Qualifiers(); |
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302 | return new TupleType( qualifiers, types ); |
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303 | } |
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304 | |
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305 | TypeInstType * isTtype( Type * type ) { |
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306 | if ( TypeInstType * inst = dynamic_cast< TypeInstType * >( type ) ) { |
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307 | if ( inst->get_baseType() && inst->get_baseType()->get_kind() == TypeDecl::Ttype ) { |
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308 | return inst; |
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309 | } |
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310 | } |
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311 | return nullptr; |
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312 | } |
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313 | |
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314 | namespace { |
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315 | /// determines if impurity (read: side-effects) may exist in a piece of code. Currently gives a very crude approximation, wherein any function call expression means the code may be impure |
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316 | struct ImpurityDetector : public WithShortCircuiting { |
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317 | ImpurityDetector( bool ignoreUnique ) : ignoreUnique( ignoreUnique ) {} |
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318 | |
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319 | void previsit( ApplicationExpr * appExpr ) { |
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320 | visit_children = false; |
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321 | if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) { |
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322 | if ( function->get_linkage() == LinkageSpec::Intrinsic ) { |
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323 | if ( function->get_name() == "*?" || function->get_name() == "?[?]" ) { |
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324 | // intrinsic dereference, subscript are pure, but need to recursively look for impurity |
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325 | visit_children = true; |
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326 | return; |
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327 | } |
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328 | } |
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329 | } |
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330 | maybeImpure = true; |
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331 | } |
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332 | void previsit( UntypedExpr * ) { maybeImpure = true; visit_children = false; } |
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333 | void previsit( UniqueExpr * ) { |
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334 | if ( ignoreUnique ) { |
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335 | // bottom out at unique expression. |
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336 | // The existence of a unique expression doesn't change the purity of an expression. |
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337 | // That is, even if the wrapped expression is impure, the wrapper protects the rest of the expression. |
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338 | visit_children = false; |
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339 | return; |
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340 | } |
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341 | } |
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342 | |
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343 | bool maybeImpure = false; |
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344 | bool ignoreUnique; |
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345 | }; |
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346 | } // namespace |
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347 | |
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348 | bool maybeImpure( Expression * expr ) { |
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349 | PassVisitor<ImpurityDetector> detector( false ); |
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350 | expr->accept( detector ); |
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351 | return detector.pass.maybeImpure; |
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352 | } |
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353 | |
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354 | bool maybeImpureIgnoreUnique( Expression * expr ) { |
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355 | PassVisitor<ImpurityDetector> detector( true ); |
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356 | expr->accept( detector ); |
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357 | return detector.pass.maybeImpure; |
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358 | } |
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359 | } // namespace Tuples |
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360 | |
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361 | // Local Variables: // |
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362 | // tab-width: 4 // |
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363 | // mode: c++ // |
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364 | // compile-command: "make install" // |
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365 | // End: // |
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