source: src/Validate/ReplaceTypedef.cpp @ 81e768d

//
// Cforall Version 1.0.0 Copyright (C) 2018 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// ReplaceTypedef.cpp -- Fill in all typedefs with the underlying type.
//
// Author           : Andrew Beach
// Created On       : Tue Jun 29 14:59:00 2022
// Last Modified By : Peter A. Buhr
// Last Modified On : Thu Dec 14 16:11:51 2023
// Update Count     : 4
//

#include "ReplaceTypedef.hpp"

#include "AST/Copy.hpp"
#include "AST/Pass.hpp"
#include "Common/ScopedMap.hpp"
#include "Common/UniqueName.hpp"
#include "ResolvExpr/Unify.hpp"

namespace Validate {

namespace {

struct ReplaceTypedefCore final :
                public ast::WithCodeLocation,
                public ast::WithDeclsToAdd,
                public ast::WithGuards,
                public ast::WithShortCircuiting,
                public ast::WithVisitorRef<ReplaceTypedefCore> {

        void previsit( ast::QualifiedType const * );
        ast::Type const * postvisit( ast::QualifiedType const * );
        ast::Type const * postvisit( ast::TypeInstType const * );
        ast::Decl const * postvisit( ast::TypedefDecl const * );
        void previsit( ast::TypeDecl const * );
        void previsit( ast::FunctionDecl const * );
        void previsit( ast::ObjectDecl const * );
        ast::DeclWithType const * postvisit( ast::ObjectDecl const * );

        void previsit( ast::CastExpr const * );
        void previsit( ast::CompoundStmt const * );
        void postvisit( ast::CompoundStmt const * );

        ast::StructDecl const * previsit( ast::StructDecl const * );
        ast::UnionDecl const * previsit( ast::UnionDecl const * );
        void previsit( ast::EnumDecl const * );
        void previsit( ast::TraitDecl const * );

        template<typename AggrDecl>
        void addImplicitTypedef( AggrDecl * aggDecl );
        template<typename AggrDecl>
        AggrDecl const * handleAggregate( AggrDecl const * aggDecl );

        using TypedefDeclPtr = ast::ptr<ast::TypedefDecl>;
        using TypedefMap = ScopedMap<std::string, std::pair<TypedefDeclPtr, int>>;
        using TypeDeclMap = ScopedMap<std::string, ast::TypeDecl const *>;

        TypedefMap typedefNames;
        TypeDeclMap typedeclNames;
        int scopeLevel;
        bool isAtFunctionTop = false;
};

void ReplaceTypedefCore::previsit( ast::QualifiedType const * ) {
        visit_children = false;
}

ast::Type const * ReplaceTypedefCore::postvisit(
                ast::QualifiedType const * type ) {
        // Replacing typedefs only makes sense for the 'oldest ancestor'
        // of the qualified type.
        return ast::mutate_field( type, &ast::QualifiedType::parent,
                type->parent->accept( *visitor ) );
}

ast::Type const * ReplaceTypedefCore::postvisit(
                ast::TypeInstType const * type ) {
        // Instances of typedef types will come here. If it is an instance
        // of a typedef type, link the instance to its actual type.
        TypedefMap::const_iterator def = typedefNames.find( type->name );
        if ( def != typedefNames.end() ) {
                ast::Type * ret = ast::deepCopy( def->second.first->base );
                ret->qualifiers |= type->qualifiers;
                // We ignore certain attributes on function parameters if they arrive
                // by typedef. GCC appears to do the same thing.
                if ( isAtFunctionTop ) {
                        erase_if( ret->attributes, []( ast::Attribute const * attr ){
                                return !attr->isValidOnFuncParam();
                        } );
                }
                for ( const auto & attribute : type->attributes ) {
                        ret->attributes.push_back( attribute );
                }
                // Place instance parameters on the typedef'd type.
                if ( !type->params.empty() ) {
                        auto rtt = dynamic_cast<ast::BaseInstType *>( ret );
                        if ( !rtt ) {
                                assert( location );
                                SemanticError( *location, "Cannot apply type parameters to base type of %s.", type->name.c_str() );
                        }
                        rtt->params.clear();
                        for ( auto it : type->params ) {
                                rtt->params.push_back( ast::deepCopy( it ) );
                        }
                        // Recursively fix typedefs on parameters.
                        ast::mutate_each( rtt, &ast::BaseInstType::params, *visitor );
                }
                return ret;
        } else {
                TypeDeclMap::const_iterator base = typedeclNames.find( type->name );
                if ( base == typedeclNames.end() ) {
                        assert( location );
                        SemanticError( *location, "Use of undefined type %s.", type->name.c_str() );
                }
                return ast::mutate_field( type, &ast::TypeInstType::base, base->second );
        }
}
struct VarLenChecker : public ast::WithShortCircuiting {
        bool result = false;
        void previsit( ast::FunctionType const * ) { visit_children = false; }
        void previsit( ast::ArrayType const * at ) { result |= at->isVarLen; }
};
static bool hasVarLen( const ast::Type * t ) {
        return ast::Pass<VarLenChecker>::read( t );
}
struct ArrayTypeExtractor {
        std::vector<const ast::ArrayType *> result;
        void postvisit( const ast::ArrayType * at ) {
                result.push_back( at );
        }
};
static bool dimensionPresenceMismatched( const ast::Type * t0, const ast::Type * t1) {
        std::vector<const ast::ArrayType *> at0s = std::move(
                ast::Pass<ArrayTypeExtractor>::read( t0 ) );
        std::vector<const ast::ArrayType *> at1s = std::move(
                ast::Pass<ArrayTypeExtractor>::read( t1 ) );
        assert( at0s.size() == at1s.size() );
        for (size_t i = 0; i < at0s.size(); i++) {
                const ast::ArrayType * at0 = at0s[i];
                const ast::ArrayType * at1 = at1s[i];
                assert( ResolvExpr::typesCompatible( at0, at1 ) );
                if ( (at0->dimension != nullptr) != (at1->dimension != nullptr) ) return true;
        }
        return false;
}
ast::Decl const * ReplaceTypedefCore::postvisit(
                ast::TypedefDecl const * decl ) {
        if ( 1 == typedefNames.count( decl->name ) &&
                        typedefNames[ decl->name ].second == scopeLevel ) {
                ast::Type const * t0 = decl->base;
                ast::Type const * t1 = typedefNames[ decl->name ].first->base;
                // [hasVarLen]
                // Cannot redefine VLA typedefs. Note: this is slightly incorrect,
                // because our notion of VLAs at this point in the translator is
                // imprecise. In particular, this will disallow redefining typedefs
                // with arrays whose dimension is an enumerator or a cast of a
                // constant/enumerator. The effort required to fix this corner case
                // likely outweighs the utility of allowing it.
                // [dimensionPresenceMismatched]
                // Core typesCompatible logic interprets absent dimensions as wildcards,
                // i.e. float[][*] matches float[][42].
                // For detecting incompatible typedefs, we have to interpret them verbatim,
                // i.e. float[] is different than float[42].
                // But typesCompatible does assure that the pair of types is structurally
                // consistent, outside of the dimension expressions.  This assurance guards
                // the dimension-presence traversal.  So this traversal logic can (and does)
                // assume that ArrayTypes will be encountered in analogous places.
                if ( !ResolvExpr::typesCompatible( t0, t1 )
                                || hasVarLen( t0 )
                                || hasVarLen( t1 )
                                || dimensionPresenceMismatched( t0, t1 ) ) {
                        SemanticError( decl->location, "Cannot redefine typedef %s", decl->name.c_str() );
                }
        } else {
                typedefNames[ decl->name ] =
                        std::make_pair( TypedefDeclPtr( decl ), scopeLevel );
        }

        // When a typedef is a forward declaration:
        // >    typedef struct screen SCREEN;
        // the declaration portion must be retained:
        // >    struct screen;
        // because the expansion of the typedef is:
        // >    void func( SCREEN * p ) -> void func( struct screen * p );
        // hence type name "screen" must be defined.
        // Note: qualifiers on the typedef are not used for the forward declaration.

        ast::Type const * designatorType = decl->base->stripDeclarator();
        if ( auto structType = dynamic_cast<ast::StructInstType const *>( designatorType ) ) {
                declsToAddBefore.push_back( new ast::StructDecl(
                        decl->location, structType->name, ast::AggregateDecl::Struct, {},
                        decl->linkage ) );
        } else if ( auto unionType = dynamic_cast<ast::UnionInstType const *>( designatorType ) ) {
                declsToAddBefore.push_back( new ast::UnionDecl(
                        decl->location, unionType->name, {}, decl->linkage ) );
        } else if ( auto enumType = dynamic_cast<ast::EnumInstType const *>( designatorType ) ) {
                declsToAddBefore.push_back( new ast::EnumDecl(
                        decl->location, enumType->name, false, {}, decl->linkage,
                        ( (enumType->base) ? enumType->base->base : nullptr )
                        ) );
        }
        return ast::deepCopy( decl );
}

void ReplaceTypedefCore::previsit( ast::TypeDecl const * decl ) {
        typedefNames.erase( decl->name );
        typedeclNames.insert( decl->name, decl );
}

void ReplaceTypedefCore::previsit( ast::FunctionDecl const * ) {
        GuardScope( typedefNames );
        GuardScope( typedeclNames );
        GuardValue( isAtFunctionTop ) = true;
}

void ReplaceTypedefCore::previsit( ast::ObjectDecl const * ) {
        GuardScope( typedefNames );
        GuardScope( typedeclNames );
}

ast::DeclWithType const * ReplaceTypedefCore::postvisit(
                ast::ObjectDecl const * decl ) {
        if ( ast::FunctionType const * type = decl->type.as<ast::FunctionType>() ) {
                using DWTVector = std::vector<ast::ptr<ast::DeclWithType>>;
                using DeclVector = std::vector<ast::ptr<ast::TypeDecl>>;
                CodeLocation const & declLocation = decl->location;
                UniqueName paramNamer( decl->name + "Param" );

                // Replace the current object declaration with a function declaration.
                ast::FunctionDecl const * newDecl = new ast::FunctionDecl(
                        declLocation,
                        decl->name,
                        map_range<DeclVector>( type->forall, []( const ast::TypeInstType * inst ) {
                                return ast::deepCopy( inst->base );
                        } ),
                        map_range<DWTVector>( type->assertions, []( const ast::VariableExpr * expr ) {
                                return ast::deepCopy( expr->var );
                        } ),
                        map_range<DWTVector>( type->params, [&declLocation, &paramNamer]( const ast::Type * type ) {
                                assert( type );
                                return new ast::ObjectDecl( declLocation, paramNamer.newName(), ast::deepCopy( type ) );
                        } ),
                        map_range<DWTVector>( type->returns, [&declLocation, &paramNamer]( const ast::Type * type ) {
                                assert( type );
                                return new ast::ObjectDecl( declLocation, paramNamer.newName(), ast::deepCopy( type ) );
                        } ),
                        nullptr,
                        decl->storage,
                        decl->linkage,
                        {/* attributes */},
                        decl->funcSpec
                );
                return newDecl;
        }
        return decl;
}

void ReplaceTypedefCore::previsit( ast::CastExpr const * ) {
        GuardScope( typedefNames );
        GuardScope( typedeclNames );
}

void ReplaceTypedefCore::previsit( ast::CompoundStmt const * ) {
        GuardScope( typedefNames );
        GuardScope( typedeclNames );
        GuardValue( isAtFunctionTop ) = false;
        scopeLevel += 1;
}

void ReplaceTypedefCore::postvisit( ast::CompoundStmt const * ) {
        scopeLevel -= 1;
}

ast::StructDecl const * ReplaceTypedefCore::previsit( ast::StructDecl const * decl ) {
        visit_children = false;
        addImplicitTypedef( decl );
        return handleAggregate( decl );
}

ast::UnionDecl const * ReplaceTypedefCore::previsit( ast::UnionDecl const * decl ) {
        visit_children = false;
        addImplicitTypedef( decl );
        return handleAggregate( decl );
}

void ReplaceTypedefCore::previsit( ast::EnumDecl const * decl ) {
        addImplicitTypedef( decl );
}

void ReplaceTypedefCore::previsit( ast::TraitDecl const * ) {
        GuardScope( typedefNames );
        GuardScope( typedeclNames );
}

template<typename AggrDecl>
void ReplaceTypedefCore::addImplicitTypedef( AggrDecl * aggrDecl ) {
        if ( 0 != typedefNames.count( aggrDecl->name ) ) {
                return;
        }
        ast::Type * type = nullptr;
        if ( auto structDecl = dynamic_cast<const ast::StructDecl *>( aggrDecl ) ) {
                type = new ast::StructInstType( structDecl->name );
        } else if ( auto unionDecl = dynamic_cast<const ast::UnionDecl *>( aggrDecl ) ) {
                type = new ast::UnionInstType( unionDecl->name );
        } else if ( auto enumDecl = dynamic_cast<const ast::EnumDecl *>( aggrDecl ) ) {
                type = new ast::EnumInstType( enumDecl->name );
        }
        assert( type );

        TypedefDeclPtr typeDecl = new ast::TypedefDecl( aggrDecl->location,
                aggrDecl->name, ast::Storage::Classes(), type, aggrDecl->linkage );
        // Add the implicit typedef to the AST.
        declsToAddAfter.push_back( ast::deepCopy( typeDecl.get() ) );
        // Shore the name in the map of names.
        typedefNames[ aggrDecl->name ] =
                std::make_pair( std::move( typeDecl ), scopeLevel );
}

template<typename AggrDecl>
AggrDecl const * ReplaceTypedefCore::handleAggregate( AggrDecl const * decl ) {
        SemanticErrorException errors;

        ValueGuard<decltype(declsToAddBefore)> oldBeforeDecls( declsToAddBefore );
        ValueGuard<decltype(declsToAddAfter )> oldAfterDecls(  declsToAddAfter );
        declsToAddBefore.clear();
        declsToAddAfter.clear();

        GuardScope( typedefNames );
        GuardScope( typedeclNames );
        decl = mutate_each( decl, &ast::AggregateDecl::params, *visitor );
        decl = mutate_each( decl, &ast::AggregateDecl::attributes, *visitor );

        auto mut = ast::mutate( decl );

        std::list<ast::ptr<ast::Decl>> members;
        // Unroll accept_all for decl->members so that implicit typedefs for
        // nested types are added to the aggregate body.
        for ( ast::ptr<ast::Decl> const & member : mut->members ) {
                assert( declsToAddBefore.empty() );
                assert( declsToAddAfter.empty() );
                ast::Decl const * newMember = nullptr;
                try {
                        newMember = member->accept( *visitor );
                } catch ( SemanticErrorException & e ) {
                        errors.append( e );
                }
                if ( !declsToAddBefore.empty() ) {
                        members.splice( members.end(), declsToAddBefore );
                }
                members.push_back( newMember );
                if ( !declsToAddAfter.empty() ) {
                        members.splice( members.end(), declsToAddAfter );
                }
        }
        assert( declsToAddBefore.empty() );
        assert( declsToAddAfter.empty() );
        errors.throwIfNonEmpty();

        mut->members.clear();
        for ( auto member : members ) {
                mut->members.push_back( member );
        }

        return mut;
}

} // namespace

void replaceTypedef( ast::TranslationUnit & translationUnit ) {
        ast::Pass<ReplaceTypedefCore> pass;
        ast::accept_all( translationUnit, pass );
        if ( pass.core.typedefNames.count( "size_t" ) ) {
                translationUnit.global.sizeType =
                        ast::deepCopy( pass.core.typedefNames["size_t"].first->base );
        } else {
                // Missing the global definition, default to long unsigned int.
                // Perhaps this should be a warning instead.
                translationUnit.global.sizeType =
                        new ast::BasicType( ast::BasicKind::LongUnsignedInt );
        }
}

} // namespace Validate

// Local Variables: //
// tab-width: 4 //
// mode: c++ //
// compile-command: "make install" //
// End: //