[c671112] | 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 | // TypeSubstitution.cc -- |
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| 8 | // |
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| 9 | // Author : Richard C. Bilson |
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| 10 | // Created On : Mon May 18 07:44:20 2015 |
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[dafe9e1] | 11 | // Last Modified By : Andrew Beach |
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[bccd70a] | 12 | // Last Modified On : Thr May 25 11:24:00 2023 |
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| 13 | // Update Count : 6 |
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[c671112] | 14 | // |
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| 15 | |
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| 16 | #include "TypeSubstitution.hpp" |
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| 17 | |
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[bccd70a] | 18 | #include "Type.hpp" // for TypeInstType, Type, StructInstType, UnionInstType |
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| 19 | #include "Pass.hpp" // for Pass, PureVisitor, WithGuards, WithVisitorRef |
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[c15085d] | 20 | |
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[bccd70a] | 21 | namespace ast { |
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[c15085d] | 22 | |
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[c671112] | 23 | TypeSubstitution::TypeSubstitution() { |
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| 24 | } |
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| 25 | |
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| 26 | TypeSubstitution::TypeSubstitution( const TypeSubstitution &other ) : Node() { |
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| 27 | initialize( other, *this ); |
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| 28 | } |
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| 29 | |
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[dafe9e1] | 30 | TypeSubstitution::~TypeSubstitution() {} |
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[c671112] | 31 | |
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| 32 | TypeSubstitution &TypeSubstitution::operator=( const TypeSubstitution &other ) { |
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| 33 | if ( this == &other ) return *this; |
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| 34 | initialize( other, *this ); |
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| 35 | return *this; |
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| 36 | } |
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| 37 | |
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| 38 | void TypeSubstitution::initialize( const TypeSubstitution &src, TypeSubstitution &dest ) { |
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[a8b87d3] | 39 | dest.typeMap.clear(); |
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[c671112] | 40 | dest.add( src ); |
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| 41 | } |
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| 42 | |
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| 43 | void TypeSubstitution::add( const TypeSubstitution &other ) { |
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[a8b87d3] | 44 | for ( TypeMap::const_iterator i = other.typeMap.begin(); i != other.typeMap.end(); ++i ) { |
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| 45 | typeMap[ i->first ] = i->second; |
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[c671112] | 46 | } // for |
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| 47 | } |
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| 48 | |
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[3e5dd913] | 49 | void TypeSubstitution::add( const TypeInstType * formalType, const Type *actualType ) { |
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[a8b87d3] | 50 | typeMap[ *formalType ] = actualType; |
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[c671112] | 51 | } |
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| 52 | |
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[93c10de] | 53 | void TypeSubstitution::add( const TypeEnvKey & key, const Type * actualType) { |
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[a8b87d3] | 54 | typeMap[ key ] = actualType; |
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[172d9342] | 55 | } |
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| 56 | |
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[3e5dd913] | 57 | void TypeSubstitution::remove( const TypeInstType * formalType ) { |
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[a8b87d3] | 58 | TypeMap::iterator i = typeMap.find( *formalType ); |
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| 59 | if ( i != typeMap.end() ) { |
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| 60 | typeMap.erase( *formalType ); |
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[c671112] | 61 | } // if |
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| 62 | } |
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| 63 | |
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[a8b87d3] | 64 | const Type *TypeSubstitution::lookup( |
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[93c10de] | 65 | const TypeEnvKey & formalType ) const { |
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[a8b87d3] | 66 | TypeMap::const_iterator i = typeMap.find( formalType ); |
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[c671112] | 67 | |
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| 68 | // break on not in substitution set |
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[a8b87d3] | 69 | if ( i == typeMap.end() ) return 0; |
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[c671112] | 70 | |
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| 71 | // attempt to transitively follow TypeInstType links. |
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| 72 | while ( const TypeInstType *actualType = i->second.as<TypeInstType>()) { |
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| 73 | // break cycles in the transitive follow |
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[a8b87d3] | 74 | if ( formalType == *actualType ) break; |
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[c671112] | 75 | |
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| 76 | // Look for the type this maps to, returning previous mapping if none-such |
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[a8b87d3] | 77 | i = typeMap.find( *actualType ); |
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| 78 | if ( i == typeMap.end() ) return actualType; |
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[c671112] | 79 | } |
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| 80 | |
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| 81 | // return type from substitution set |
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| 82 | return i->second; |
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| 83 | } |
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| 84 | |
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[a8b87d3] | 85 | const Type *TypeSubstitution::lookup( const TypeInstType * formalType ) const { |
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[93c10de] | 86 | return lookup( ast::TypeEnvKey( *formalType ) ); |
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[a8b87d3] | 87 | } |
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| 88 | |
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[c671112] | 89 | bool TypeSubstitution::empty() const { |
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[a8b87d3] | 90 | return typeMap.empty(); |
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[c671112] | 91 | } |
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| 92 | |
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| 93 | namespace { |
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| 94 | struct EnvTrimmer { |
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[55b6476] | 95 | const TypeSubstitution * env; |
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[c671112] | 96 | TypeSubstitution * newEnv; |
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| 97 | EnvTrimmer( const TypeSubstitution * env, TypeSubstitution * newEnv ) : env( env ), newEnv( newEnv ){} |
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[9e23b446] | 98 | void previsit( const FunctionType * ftype ) { |
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[c671112] | 99 | // transfer known bindings for seen type variables |
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[3e5dd913] | 100 | for (auto & formal : ftype->forall) { |
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| 101 | if ( const Type * t = env->lookup( formal ) ) { |
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| 102 | newEnv->add( formal, t ); |
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| 103 | } |
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[c671112] | 104 | } |
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| 105 | } |
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| 106 | }; |
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| 107 | } // namespace |
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| 108 | |
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| 109 | /// reduce environment to just the parts that are referenced in a given expression |
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| 110 | TypeSubstitution * TypeSubstitution::newFromExpr( const Expr * expr, const TypeSubstitution * env ) { |
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| 111 | if ( env ) { |
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| 112 | TypeSubstitution * newEnv = new TypeSubstitution(); |
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| 113 | Pass<EnvTrimmer> trimmer( env, newEnv ); |
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| 114 | expr->accept( trimmer ); |
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| 115 | return newEnv; |
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| 116 | } |
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| 117 | return nullptr; |
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| 118 | } |
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| 119 | |
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[bccd70a] | 120 | // definitition must happen after PassVisitor is included so that WithGuards can be used |
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| 121 | struct TypeSubstitution::Substituter : public WithGuards, public WithVisitorRef<Substituter>, public PureVisitor { |
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| 122 | //static size_t traceId; |
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| 123 | |
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| 124 | Substituter( const TypeSubstitution & sub, bool freeOnly ) : sub( sub ), freeOnly( freeOnly ) {} |
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| 125 | |
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| 126 | const Type * postvisit( const TypeInstType * aggregateUseType ); |
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| 127 | |
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| 128 | /// Records type variable bindings from forall-statements |
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| 129 | void previsit( const FunctionType * type ); |
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| 130 | /// Records type variable bindings from forall-statements and instantiations of generic types |
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| 131 | // void handleAggregateType( const BaseInstType * type ); |
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| 132 | |
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| 133 | // void previsit( const StructInstType * aggregateUseType ); |
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| 134 | // void previsit( const UnionInstType * aggregateUseType ); |
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| 135 | |
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| 136 | const TypeSubstitution & sub; |
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| 137 | int subCount = 0; |
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| 138 | bool freeOnly; |
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| 139 | typedef std::unordered_set< TypeEnvKey > BoundVarsType; |
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| 140 | BoundVarsType boundVars; |
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| 141 | }; |
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| 142 | |
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| 143 | // size_t TypeSubstitution::Substituter::traceId = Stats::Heap::new_stacktrace_id("TypeSubstitution"); |
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| 144 | |
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[c671112] | 145 | void TypeSubstitution::normalize() { |
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[55b6476] | 146 | Pass<Substituter> sub( *this, true ); |
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[c671112] | 147 | do { |
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[7ff3e522] | 148 | sub.core.subCount = 0; |
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| 149 | sub.core.freeOnly = true; |
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[a8b87d3] | 150 | for ( TypeMap::iterator i = typeMap.begin(); i != typeMap.end(); ++i ) { |
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[55b6476] | 151 | i->second = i->second->accept( sub ); |
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[c671112] | 152 | } |
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[7ff3e522] | 153 | } while ( sub.core.subCount ); |
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[c671112] | 154 | } |
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| 155 | |
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[bccd70a] | 156 | TypeSubstitution::ApplyResult<Node> TypeSubstitution::applyBase( |
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| 157 | const Node * input, bool isFree ) const { |
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| 158 | assert( input ); |
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| 159 | Pass<Substituter> sub( *this, isFree ); |
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| 160 | const Node * output = input->accept( sub ); |
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| 161 | return { output, sub.core.subCount }; |
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| 162 | } |
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| 163 | |
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[55b6476] | 164 | const Type * TypeSubstitution::Substituter::postvisit( const TypeInstType *inst ) { |
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[3e5dd913] | 165 | BoundVarsType::const_iterator bound = boundVars.find( *inst ); |
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[c671112] | 166 | if ( bound != boundVars.end() ) return inst; |
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| 167 | |
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[a8b87d3] | 168 | TypeMap::const_iterator i = sub.typeMap.find( *inst ); |
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| 169 | if ( i == sub.typeMap.end() ) { |
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[c671112] | 170 | return inst; |
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| 171 | } else { |
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| 172 | // cut off infinite loop for the case where a type is bound to itself. |
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| 173 | // Note: this does not prevent cycles in the general case, so it may be necessary to do something more sophisticated here. |
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| 174 | // TODO: investigate preventing type variables from being bound to themselves in the first place. |
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[55b6476] | 175 | if ( const TypeInstType * replacement = i->second.as<TypeInstType>() ) { |
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[3e5dd913] | 176 | if ( *inst == *replacement ) { |
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[c671112] | 177 | return inst; |
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| 178 | } |
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| 179 | } |
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| 180 | // std::cerr << "found " << inst->name << ", replacing with " << i->second << std::endl; |
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| 181 | subCount++; |
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[55b6476] | 182 | ptr<Type> newType = i->second; // force clone if needed |
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| 183 | add_qualifiers( newType, inst->qualifiers ); |
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[2890212] | 184 | // Note: need to recursively apply substitution to the new type because normalize does not |
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[55b6476] | 185 | // substitute bound vars, but bound vars must be substituted when not in freeOnly mode. |
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| 186 | newType = newType->accept( *visitor ); |
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| 187 | return newType.release(); |
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[c671112] | 188 | } // if |
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| 189 | } |
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| 190 | |
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[361bf01] | 191 | void TypeSubstitution::Substituter::previsit( const FunctionType * ptype ) { |
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[c671112] | 192 | GuardValue( boundVars ); |
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| 193 | // bind type variables from forall-qualifiers |
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| 194 | if ( freeOnly ) { |
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[3e5dd913] | 195 | for ( auto & tyvar : ptype->forall ) { |
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| 196 | boundVars.insert( *tyvar ); |
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[c671112] | 197 | } // for |
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| 198 | } // if |
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| 199 | } |
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| 200 | |
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[3e5dd913] | 201 | /* |
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[98e8b3b] | 202 | void TypeSubstitution::Substituter::handleAggregateType( const BaseInstType * type ) { |
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[c671112] | 203 | GuardValue( boundVars ); |
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| 204 | // bind type variables from forall-qualifiers |
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| 205 | if ( freeOnly ) { |
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| 206 | // bind type variables from generic type instantiations |
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[55b6476] | 207 | if ( auto decl = type->aggr() ) { |
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[417117e] | 208 | if ( ! type->params.empty() ) { |
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| 209 | for ( const TypeDecl * tyvar : decl->params ) { |
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[3e5dd913] | 210 | boundVars.insert( *tyvar ); |
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[55b6476] | 211 | } // for |
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| 212 | } // if |
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| 213 | } |
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[c671112] | 214 | } // if |
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| 215 | } |
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| 216 | |
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[55b6476] | 217 | void TypeSubstitution::Substituter::previsit( const StructInstType * aggregateUseType ) { |
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[c671112] | 218 | handleAggregateType( aggregateUseType ); |
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| 219 | } |
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| 220 | |
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[55b6476] | 221 | void TypeSubstitution::Substituter::previsit( const UnionInstType *aggregateUseType ) { |
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[c671112] | 222 | handleAggregateType( aggregateUseType ); |
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| 223 | } |
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[3e5dd913] | 224 | */ |
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[c671112] | 225 | |
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| 226 | } // namespace ast |
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| 227 | |
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| 228 | // Local Variables: // |
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| 229 | // tab-width: 4 // |
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| 230 | // mode: c++ // |
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| 231 | // compile-command: "make install" // |
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| 232 | // End: // |
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