source: src/SymTab/Autogen.cc @ f403c46

//
// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// Autogen.cc --
//
// Author           : Rob Schluntz
// Created On       : Thu Mar 03 15:45:56 2016
// Last Modified By : Peter A. Buhr
// Last Modified On : Fri Apr 27 14:39:06 2018
// Update Count     : 63
//

#include "Autogen.h"

#include <algorithm>               // for count_if
#include <cassert>                 // for strict_dynamic_cast, assert, assertf
#include <iterator>                // for back_insert_iterator, back_inserter
#include <list>                    // for list, _List_iterator, list<>::iter...
#include <set>                     // for set, _Rb_tree_const_iterator
#include <utility>                 // for pair
#include <vector>                  // for vector

#include "AST/Decl.hpp"
#include "CodeGen/OperatorTable.h" // for isCtorDtor, isCtorDtorAssign
#include "Common/PassVisitor.h"    // for PassVisitor
#include "Common/ScopedMap.h"      // for ScopedMap<>::const_iterator, Scope...
#include "Common/utility.h"        // for cloneAll, operator+
#include "GenPoly/ScopedSet.h"     // for ScopedSet, ScopedSet<>::iterator
#include "InitTweak/GenInit.h"     // for fixReturnStatements
#include "ResolvExpr/Resolver.h"   // for resolveDecl
#include "SymTab/Mangler.h"        // for Mangler
#include "SynTree/Attribute.h"     // For Attribute
#include "SynTree/Mutator.h"       // for maybeMutate
#include "SynTree/Statement.h"     // for CompoundStmt, ReturnStmt, ExprStmt
#include "SynTree/Type.h"          // for FunctionType, Type, TypeInstType
#include "SynTree/Visitor.h"       // for maybeAccept, Visitor, acceptAll
#include "CompilationState.h"

class Attribute;

namespace SymTab {
        /// Data used to generate functions generically. Specifically, the name of the generated function and a function which generates the routine protoype
        struct FuncData {
                typedef FunctionType * (*TypeGen)( Type *, bool );
                FuncData( const std::string & fname, const TypeGen & genType ) : fname( fname ), genType( genType ) {}
                std::string fname;
                TypeGen genType;
        };

        struct AutogenerateRoutines final : public WithDeclsToAdd, public WithVisitorRef<AutogenerateRoutines>, public WithGuards, public WithShortCircuiting, public WithIndexer {
                AutogenerateRoutines();

                void previsit( EnumDecl * enumDecl );
                void previsit( StructDecl * structDecl );
                void previsit( UnionDecl * structDecl );
                void previsit( TypeDecl * typeDecl );
                void previsit( TraitDecl * traitDecl );
                void previsit( FunctionDecl * functionDecl );

                void previsit( CompoundStmt * compoundStmt );

          private:

                GenPoly::ScopedSet< std::string > structsDone;
                unsigned int functionNesting = 0;     // current level of nested functions

                std::vector< FuncData > data;
        };

        /// generates routines for tuple types.
        struct AutogenTupleRoutines : public WithDeclsToAdd, public WithVisitorRef<AutogenTupleRoutines>, public WithGuards, public WithShortCircuiting {
                void previsit( FunctionDecl * functionDecl );

                void postvisit( TupleType * tupleType );

                void previsit( CompoundStmt * compoundStmt );

          private:
                unsigned int functionNesting = 0;     // current level of nested functions
                GenPoly::ScopedSet< std::string > seenTuples;
        };

        void autogenerateRoutines( std::list< Declaration * > &translationUnit ) {
                PassVisitor<AutogenerateRoutines> generator;
                acceptAll( translationUnit, generator );

                // needs to be done separately because AutogenerateRoutines skips types that appear as function arguments, etc.
                // AutogenTupleRoutines tupleGenerator;
                // acceptAll( translationUnit, tupleGenerator );
        }

        //=============================================================================================
        // FuncGenerator definitions
        //=============================================================================================
        class FuncGenerator {
        public:
                std::list< Declaration * > definitions, forwards;

                FuncGenerator( Type * type, const std::vector< FuncData > & data, unsigned int functionNesting, SymTab::Indexer & indexer ) : type( type ), data( data ), functionNesting( functionNesting ), indexer( indexer ) {}

                virtual bool shouldAutogen() const = 0;
                void genStandardFuncs();
                virtual void genFieldCtors() = 0;
        protected:
                Type * type;
                const std::vector< FuncData > & data;
                unsigned int functionNesting;
                SymTab::Indexer & indexer;

                virtual void genFuncBody( FunctionDecl * dcl ) = 0;
                virtual bool isConcurrentType() const = 0;

                void resolve( FunctionDecl * dcl );
                void generatePrototypes( std::list< FunctionDecl * > & newFuncs );
        };

        class StructFuncGenerator : public FuncGenerator {
                StructDecl * aggregateDecl;
        public:
                StructFuncGenerator( StructDecl * aggregateDecl, StructInstType * refType, const std::vector< FuncData > & data,  unsigned int functionNesting, SymTab::Indexer & indexer ) : FuncGenerator( refType, data, functionNesting, indexer ), aggregateDecl( aggregateDecl) {}

                virtual bool shouldAutogen() const override;
                virtual bool isConcurrentType() const override;

                virtual void genFuncBody( FunctionDecl * dcl ) override;
                virtual void genFieldCtors() override;

        private:
                /// generates a single struct member operation (constructor call, destructor call, assignment call)
                void makeMemberOp( ObjectDecl * dstParam, Expression * src, DeclarationWithType * field, FunctionDecl * func, bool forward = true );

                /// generates the body of a struct function by iterating the struct members (via parameters) - generates default ctor, copy ctor, assignment, and dtor bodies, but NOT field ctor bodies
                template<typename Iterator>
                void makeFunctionBody( Iterator member, Iterator end, FunctionDecl * func, bool forward = true );

                /// generate the body of a constructor which takes parameters that match fields, e.g.
                /// void ?{}(A *, int) and void?{}(A *, int, int) for a struct A which has two int fields.
                template<typename Iterator>
                void makeFieldCtorBody( Iterator member, Iterator end, FunctionDecl * func );
        };

        class UnionFuncGenerator : public FuncGenerator {
                UnionDecl * aggregateDecl;
        public:
                UnionFuncGenerator( UnionDecl * aggregateDecl, UnionInstType * refType, const std::vector< FuncData > & data,  unsigned int functionNesting, SymTab::Indexer & indexer ) : FuncGenerator( refType, data, functionNesting, indexer ), aggregateDecl( aggregateDecl) {}

                virtual bool shouldAutogen() const override;
                virtual bool isConcurrentType() const override;

                virtual void genFuncBody( FunctionDecl * dcl ) override;
                virtual void genFieldCtors() override;

        private:
                /// generates a single struct member operation (constructor call, destructor call, assignment call)
                template<typename OutputIterator>
                void makeMemberOp( ObjectDecl * srcParam, ObjectDecl * dstParam, OutputIterator out );

                /// generates the body of a struct function by iterating the struct members (via parameters) - generates default ctor, copy ctor, assignment, and dtor bodies, but NOT field ctor bodies
                template<typename Iterator>
                void makeFunctionBody( Iterator member, Iterator end, FunctionDecl * func, bool forward = true );

                /// generate the body of a constructor which takes parameters that match fields, e.g.
                /// void ?{}(A *, int) and void?{}(A *, int, int) for a struct A which has two int fields.
                template<typename Iterator>
                void makeFieldCtorBody( Iterator member, Iterator end, FunctionDecl * func );
        };

        class EnumFuncGenerator : public FuncGenerator {
        public:
                EnumFuncGenerator( EnumInstType * refType, const std::vector< FuncData > & data,  unsigned int functionNesting, SymTab::Indexer & indexer ) : FuncGenerator( refType, data, functionNesting, indexer ) {}

                virtual bool shouldAutogen() const override;
                virtual bool isConcurrentType() const override;

                virtual void genFuncBody( FunctionDecl * dcl ) override;
                virtual void genFieldCtors() override;

        private:
        };

        class TypeFuncGenerator : public FuncGenerator {
                TypeDecl * typeDecl;
        public:
                TypeFuncGenerator( TypeDecl * typeDecl, TypeInstType * refType, const std::vector<FuncData> & data, unsigned int functionNesting, SymTab::Indexer & indexer ) : FuncGenerator( refType, data, functionNesting, indexer ), typeDecl( typeDecl ) {}

                virtual bool shouldAutogen() const override;
                virtual void genFuncBody( FunctionDecl * dcl ) override;
                virtual bool isConcurrentType() const override;
                virtual void genFieldCtors() override;
        };

        //=============================================================================================
        // helper functions
        //=============================================================================================
        void generateFunctions( FuncGenerator & gen, std::list< Declaration * > & declsToAdd ) {
                if ( ! gen.shouldAutogen() ) return;

                // generate each of the functions based on the supplied FuncData objects
                gen.genStandardFuncs();
                gen.genFieldCtors();

                declsToAdd.splice( declsToAdd.end(), gen.forwards );
                declsToAdd.splice( declsToAdd.end(), gen.definitions );
        }

        bool isUnnamedBitfield( ObjectDecl * obj ) {
                return obj != nullptr && obj->name == "" && obj->bitfieldWidth != nullptr;
        }

        bool isUnnamedBitfield( const ast::ObjectDecl * obj ) {
                return obj && obj->name.empty() && obj->bitfieldWidth;
        }

        /// inserts a forward declaration for functionDecl into declsToAdd
        void addForwardDecl( FunctionDecl * functionDecl, std::list< Declaration * > & declsToAdd ) {
                FunctionDecl * decl = functionDecl->clone();
                delete decl->statements;
                decl->statements = nullptr;
                declsToAdd.push_back( decl );
                decl->fixUniqueId();
        }

        const std::list< TypeDecl * > getGenericParams( Type * t ) {
                std::list< TypeDecl * > * ret = nullptr;
                if ( StructInstType * inst = dynamic_cast< StructInstType * > ( t ) ) {
                        ret = inst->get_baseParameters();
                } else if ( UnionInstType * inst = dynamic_cast< UnionInstType * >( t ) ) {
                        ret = inst->get_baseParameters();
                }
                return ret ? *ret : std::list< TypeDecl * >();
        }

        // shallow copy the pointer list for return
        std::vector<ast::ptr<ast::TypeDecl>> getGenericParams (const ast::Type * t) {
                if (auto structInst = dynamic_cast<const ast::StructInstType*>(t)) {
                        return structInst->base->params;
                }
                if (auto unionInst = dynamic_cast<const ast::UnionInstType*>(t)) {
                        return unionInst->base->params;
                }
                return {};
        }

        /// given type T, generate type of default ctor/dtor, i.e. function type void (*) (T *)
        FunctionType * genDefaultType( Type * paramType, bool maybePolymorphic ) {
                FunctionType *ftype = new FunctionType( Type::Qualifiers(), false );
                if ( maybePolymorphic ) {
                        // only copy in
                        const auto & typeParams = getGenericParams( paramType );
                        cloneAll( typeParams, ftype->forall );
                }
                ObjectDecl *dstParam = new ObjectDecl( "_dst", Type::StorageClasses(), LinkageSpec::Cforall, nullptr, new ReferenceType( Type::Qualifiers(), paramType->clone() ), nullptr );
                ftype->parameters.push_back( dstParam );
                return ftype;
        }

        /// Given type T, generate type of default ctor/dtor, i.e. function type void (*) (T &).
        ast::FunctionDecl * genDefaultFunc(const CodeLocation loc, const std::string fname, const ast::Type * paramType, bool maybePolymorphic) {
                std::vector<ast::ptr<ast::TypeDecl>> typeParams;
                if (maybePolymorphic) typeParams = getGenericParams(paramType);
                auto dstParam = new ast::ObjectDecl(loc, "_dst", new ast::ReferenceType(paramType), nullptr, {}, ast::Linkage::Cforall);
                return new ast::FunctionDecl(loc, fname, std::move(typeParams), {dstParam}, {}, new ast::CompoundStmt(loc), {}, ast::Linkage::Cforall);
        }

        /// given type T, generate type of copy ctor, i.e. function type void (*) (T *, T)
        FunctionType * genCopyType( Type * paramType, bool maybePolymorphic ) {
                FunctionType *ftype = genDefaultType( paramType, maybePolymorphic );
                ObjectDecl *srcParam = new ObjectDecl( "_src", Type::StorageClasses(), LinkageSpec::Cforall, nullptr, paramType->clone(), nullptr );
                ftype->parameters.push_back( srcParam );
                return ftype;
        }

        /// given type T, generate type of assignment, i.e. function type T (*) (T *, T)
        FunctionType * genAssignType( Type * paramType, bool maybePolymorphic ) {
                FunctionType *ftype = genCopyType( paramType, maybePolymorphic );
                ObjectDecl *returnVal = new ObjectDecl( "_ret", Type::StorageClasses(), LinkageSpec::Cforall, nullptr, paramType->clone(), nullptr );
                ftype->returnVals.push_back( returnVal );
                return ftype;
        }

        /// generate a function decl from a name and type. Nesting depth determines whether
        /// the declaration is static or not; optional paramter determines if declaration is intrinsic
        FunctionDecl * genFunc( const std::string & fname, FunctionType * ftype, unsigned int functionNesting, bool isIntrinsic = false  ) {
                // Routines at global scope marked "static" to prevent multiple definitions in separate translation units
                // because each unit generates copies of the default routines for each aggregate.
                Type::StorageClasses scs = functionNesting > 0 ? Type::StorageClasses() : Type::StorageClasses( Type::Static );
                LinkageSpec::Spec spec = isIntrinsic ? LinkageSpec::Intrinsic : LinkageSpec::AutoGen;
                FunctionDecl * decl = new FunctionDecl( fname, scs, spec, ftype, new CompoundStmt(),
                                                                                                std::list< Attribute * >(), Type::FuncSpecifiers( Type::Inline ) );
                decl->fixUniqueId();
                return decl;
        }

        Type * declToType( Declaration * decl ) {
                if ( DeclarationWithType * dwt = dynamic_cast< DeclarationWithType * >( decl ) ) {
                        return dwt->get_type();
                }
                return nullptr;
        }

        Type * declToTypeDeclBase( Declaration * decl ) {
                if ( TypeDecl * td = dynamic_cast< TypeDecl * >( decl ) ) {
                        return td->base;
                }
                return nullptr;
        }

        //=============================================================================================
        // FuncGenerator member definitions
        //=============================================================================================
        void FuncGenerator::genStandardFuncs() {
                std::list< FunctionDecl * > newFuncs;
                generatePrototypes( newFuncs );

                for ( FunctionDecl * dcl : newFuncs ) {
                        genFuncBody( dcl );
                        if ( CodeGen::isAssignment( dcl->name ) ) {
                                // assignment needs to return a value
                                FunctionType * assignType = dcl->type;
                                assert( assignType->parameters.size() == 2 );
                                assert( assignType->returnVals.size() == 1 );
                                ObjectDecl * dstParam = strict_dynamic_cast< ObjectDecl * >( assignType->parameters.front() );
                                dcl->statements->push_back( new ReturnStmt( new VariableExpr( dstParam ) ) );
                        }
                        resolve( dcl );
                }
        }

        void FuncGenerator::generatePrototypes( std::list< FunctionDecl * > & newFuncs ) {
                bool concurrent_type = isConcurrentType();
                for ( const FuncData & d : data ) {
                        // generate a function (?{}, ?=?, ^?{}) based on the current FuncData.
                        FunctionType * ftype = d.genType( type, true );

                        // destructor for concurrent type must be mutex
                        if ( concurrent_type && CodeGen::isDestructor( d.fname ) ) {
                                ftype->parameters.front()->get_type()->set_mutex( true );
                        }

                        newFuncs.push_back( genFunc( d.fname, ftype, functionNesting ) );
                }
        }

        void FuncGenerator::resolve( FunctionDecl * dcl ) {
                try {
                        if (!useNewAST) // attempt to delay resolver call
                                ResolvExpr::resolveDecl( dcl, indexer );
                        if ( functionNesting == 0 ) {
                                // forward declare if top-level struct, so that
                                // type is complete as soon as its body ends
                                // Note: this is necessary if we want structs which contain
                                // generic (otype) structs as members.
                                addForwardDecl( dcl, forwards );
                        }
                        definitions.push_back( dcl );
                        indexer.addId( dcl );
                } catch ( SemanticErrorException & ) {
                        // okay if decl does not resolve - that means the function should not be generated
                        // delete dcl;
                        delete dcl->statements;
                        dcl->statements = nullptr;
                        dcl->isDeleted = true;
                        definitions.push_back( dcl );
                        indexer.addId( dcl );
                }
        }

        bool StructFuncGenerator::shouldAutogen() const {
                // Builtins do not use autogeneration.
                return ! aggregateDecl->linkage.is_builtin;
        }
        bool StructFuncGenerator::isConcurrentType() const { return aggregateDecl->is_thread() || aggregateDecl->is_monitor(); }

        void StructFuncGenerator::genFuncBody( FunctionDecl * dcl ) {
                // generate appropriate calls to member ctor, assignment
                // destructor needs to do everything in reverse, so pass "forward" based on whether the function is a destructor
                if ( ! CodeGen::isDestructor( dcl->name ) ) {
                        makeFunctionBody( aggregateDecl->members.begin(), aggregateDecl->members.end(), dcl );
                } else {
                        makeFunctionBody( aggregateDecl->members.rbegin(), aggregateDecl->members.rend(), dcl, false );
                }
        }

        void StructFuncGenerator::genFieldCtors() {
                // field ctors are only generated if default constructor and copy constructor are both generated
                unsigned numCtors = std::count_if( definitions.begin(), definitions.end(), [](Declaration * dcl) { return CodeGen::isConstructor( dcl->name ); } );

                // Field constructors are only generated if default and copy constructor
                // are generated, since they need access to both
                if ( numCtors != 2 ) return;

                // create constructors which take each member type as a parameter.
                // for example, for struct A { int x, y; }; generate
                //   void ?{}(A *, int) and void ?{}(A *, int, int)
                FunctionType * memCtorType = genDefaultType( type );
                for ( Declaration * member : aggregateDecl->members ) {
                        DeclarationWithType * field = strict_dynamic_cast<DeclarationWithType *>( member );
                        if ( isUnnamedBitfield( dynamic_cast< ObjectDecl * > ( field ) ) ) {
                                // don't make a function whose parameter is an unnamed bitfield
                                continue;
                        }
                        // do not carry over field's attributes to parameter type
                        Type * paramType = field->get_type()->clone();
                        deleteAll( paramType->attributes );
                        paramType->attributes.clear();
                        // add a parameter corresponding to this field
                        ObjectDecl * param = new ObjectDecl( field->name, Type::StorageClasses(), LinkageSpec::Cforall, nullptr, paramType, nullptr );
                        cloneAll_if( field->attributes, param->attributes, [](Attribute * attr) { return attr->isValidOnFuncParam(); } );
                        memCtorType->parameters.push_back( param );
                        FunctionDecl * ctor = genFunc( "?{}", memCtorType->clone(), functionNesting );
                        makeFieldCtorBody( aggregateDecl->members.begin(), aggregateDecl->members.end(), ctor );
                        resolve( ctor );
                }
                delete memCtorType;
        }

        void StructFuncGenerator::makeMemberOp( ObjectDecl * dstParam, Expression * src, DeclarationWithType * field, FunctionDecl * func, bool forward ) {
                InitTweak::InitExpander_old srcParam( src );

                // assign to destination
                Expression *dstselect = new MemberExpr( field, new CastExpr( new VariableExpr( dstParam ), strict_dynamic_cast< ReferenceType* >( dstParam->get_type() )->base->clone() ) );
                genImplicitCall( srcParam, dstselect, func->name, back_inserter( func->statements->kids ), field, forward );
        }

        template<typename Iterator>
        void StructFuncGenerator::makeFunctionBody( Iterator member, Iterator end, FunctionDecl * func, bool forward ) {
                for ( ; member != end; ++member ) {
                        if ( DeclarationWithType *field = dynamic_cast< DeclarationWithType * >( *member ) ) { // otherwise some form of type declaration, e.g. Aggregate
                                // query the type qualifiers of this field and skip assigning it if it is marked const.
                                // If it is an array type, we need to strip off the array layers to find its qualifiers.
                                Type * type = field->get_type();
                                while ( ArrayType * at = dynamic_cast< ArrayType * >( type ) ) {
                                        type = at->get_base();
                                }

                                if ( type->get_const() && CodeGen::isAssignment( func->name ) ) {
                                        // don't assign const members, but do construct/destruct
                                        continue;
                                }

                                assert( ! func->get_functionType()->get_parameters().empty() );
                                ObjectDecl * dstParam = dynamic_cast<ObjectDecl*>( func->get_functionType()->get_parameters().front() );
                                ObjectDecl * srcParam = nullptr;
                                if ( func->get_functionType()->get_parameters().size() == 2 ) {
                                        srcParam = dynamic_cast<ObjectDecl*>( func->get_functionType()->get_parameters().back() );
                                }

                                // srcParam may be NULL, in which case we have default ctor/dtor
                                assert( dstParam );

                                Expression *srcselect = srcParam ? new MemberExpr( field, new VariableExpr( srcParam ) ) : nullptr;
                                makeMemberOp( dstParam, srcselect, field, func, forward );
                        } // if
                } // for
        } // makeFunctionBody

        template<typename Iterator>
        void StructFuncGenerator::makeFieldCtorBody( Iterator member, Iterator end, FunctionDecl * func ) {
                FunctionType * ftype = func->type;
                std::list<DeclarationWithType*> & params = ftype->parameters;
                assert( params.size() >= 2 );  // should not call this function for default ctor, etc.

                // skip 'this' parameter
                ObjectDecl * dstParam = dynamic_cast<ObjectDecl*>( params.front() );
                assert( dstParam );
                std::list<DeclarationWithType*>::iterator parameter = params.begin()+1;
                for ( ; member != end; ++member ) {
                        if ( DeclarationWithType * field = dynamic_cast<DeclarationWithType*>( *member ) ) {
                                if ( isUnnamedBitfield( dynamic_cast< ObjectDecl * > ( field ) ) ) {
                                        // don't make a function whose parameter is an unnamed bitfield
                                        continue;
                                } else if ( parameter != params.end() ) {
                                        // matching parameter, initialize field with copy ctor
                                        Expression *srcselect = new VariableExpr(*parameter);
                                        makeMemberOp( dstParam, srcselect, field, func );
                                        ++parameter;
                                } else {
                                        // no matching parameter, initialize field with default ctor
                                        makeMemberOp( dstParam, nullptr, field, func );
                                }
                        }
                }
        }

        bool UnionFuncGenerator::shouldAutogen() const {
                // Builtins do not use autogeneration.
                return ! aggregateDecl->linkage.is_builtin;
        }

        // xxx - is this right?
        bool UnionFuncGenerator::isConcurrentType() const { return false; };

        /// generate a single union assignment expression (using memcpy)
        template< typename OutputIterator >
        void UnionFuncGenerator::makeMemberOp( ObjectDecl * srcParam, ObjectDecl * dstParam, OutputIterator out ) {
                UntypedExpr *copy = new UntypedExpr( new NameExpr( "__builtin_memcpy" ) );
                copy->args.push_back( new AddressExpr( new VariableExpr( dstParam ) ) );
                copy->args.push_back( new AddressExpr( new VariableExpr( srcParam ) ) );
                copy->args.push_back( new SizeofExpr( srcParam->get_type()->clone() ) );
                *out++ = new ExprStmt( copy );
        }

        /// generates the body of a union assignment/copy constructor/field constructor
        void UnionFuncGenerator::genFuncBody( FunctionDecl * funcDecl ) {
                FunctionType * ftype = funcDecl->type;
                if ( InitTweak::isCopyConstructor( funcDecl ) || InitTweak::isAssignment( funcDecl ) ) {
                        assert( ftype->parameters.size() == 2 );
                        ObjectDecl * dstParam = strict_dynamic_cast< ObjectDecl * >( ftype->parameters.front() );
                        ObjectDecl * srcParam = strict_dynamic_cast< ObjectDecl * >( ftype->parameters.back() );
                        makeMemberOp( srcParam, dstParam, back_inserter( funcDecl->statements->kids ) );
                } else {
                        // default ctor/dtor body is empty - add unused attribute to parameter to silence warnings
                        assert( ftype->parameters.size() == 1 );
                        ObjectDecl * dstParam = strict_dynamic_cast< ObjectDecl * >( ftype->parameters.front() );
                        dstParam->attributes.push_back( new Attribute( "unused" ) );
                }
        }

        /// generate the body of a constructor which takes parameters that match fields, e.g.
        /// void ?{}(A *, int) and void?{}(A *, int, int) for a struct A which has two int fields.
        void UnionFuncGenerator::genFieldCtors() {
                // field ctors are only generated if default constructor and copy constructor are both generated
                unsigned numCtors = std::count_if( definitions.begin(), definitions.end(), [](Declaration * dcl) { return CodeGen::isConstructor( dcl->get_name() ); } );

                // Field constructors are only generated if default and copy constructor
                // are generated, since they need access to both
                if ( numCtors != 2 ) return;

                // create a constructor which takes the first member type as a parameter.
                // for example, for Union A { int x; double y; }; generate
                // void ?{}(A *, int)
                // This is to mimic C's behaviour which initializes the first member of the union.
                FunctionType * memCtorType = genDefaultType( type );
                for ( Declaration * member : aggregateDecl->members ) {
                        DeclarationWithType * field = strict_dynamic_cast<DeclarationWithType *>( member );
                        if ( isUnnamedBitfield( dynamic_cast< ObjectDecl * > ( field ) ) ) {
                                // don't make a function whose parameter is an unnamed bitfield
                                break;
                        }
                        // do not carry over field's attributes to parameter type
                        Type * paramType = field->get_type()->clone();
                        deleteAll( paramType->attributes );
                        paramType->attributes.clear();
                        // add a parameter corresponding to this field
                        memCtorType->parameters.push_back( new ObjectDecl( field->name, Type::StorageClasses(), LinkageSpec::Cforall, nullptr, paramType, nullptr ) );
                        FunctionDecl * ctor = genFunc( "?{}", memCtorType->clone(), functionNesting );
                        ObjectDecl * srcParam = strict_dynamic_cast<ObjectDecl *>( ctor->type->parameters.back() );
                        srcParam->fixUniqueId();
                        ObjectDecl * dstParam = InitTweak::getParamThis( ctor->type );
                        makeMemberOp( srcParam, dstParam, back_inserter( ctor->statements->kids ) );
                        resolve( ctor );
                        // only generate one field ctor for unions
                        break;
                }
                delete memCtorType;
        }

        void EnumFuncGenerator::genFuncBody( FunctionDecl * funcDecl ) {
                // xxx - Temporary: make these functions intrinsic so they codegen as C assignment.
                // Really they're something of a cross between instrinsic and autogen, so should
                // probably make a new linkage type
                funcDecl->linkage = LinkageSpec::Intrinsic;
                FunctionType * ftype = funcDecl->type;
                if ( InitTweak::isCopyConstructor( funcDecl ) || InitTweak::isAssignment( funcDecl ) ) {
                        assert( ftype->parameters.size() == 2 );
                        ObjectDecl * dstParam = strict_dynamic_cast< ObjectDecl * >( ftype->parameters.front() );
                        ObjectDecl * srcParam = strict_dynamic_cast< ObjectDecl * >( ftype->parameters.back() );

                        // enum copy construct and assignment is just C-style assignment.
                        // this looks like a bad recursive call, but code gen will turn it into
                        // a C-style assignment.
                        // This happens before function pointer type conversion, so need to do it manually here
                        ApplicationExpr * callExpr = new ApplicationExpr( VariableExpr::functionPointer( funcDecl ) );
                        callExpr->get_args().push_back( new VariableExpr( dstParam ) );
                        callExpr->get_args().push_back( new VariableExpr( srcParam ) );
                        funcDecl->statements->push_back( new ExprStmt( callExpr ) );
                } else {
                        // default ctor/dtor body is empty - add unused attribute to parameter to silence warnings
                        assert( ftype->parameters.size() == 1 );
                        ObjectDecl * dstParam = strict_dynamic_cast< ObjectDecl * >( ftype->parameters.front() );
                        dstParam->attributes.push_back( new Attribute( "unused" ) );
                }
        }

        bool EnumFuncGenerator::shouldAutogen() const { return true; }
        bool EnumFuncGenerator::isConcurrentType() const { return false; }
        // enums do not have field constructors
        void EnumFuncGenerator::genFieldCtors() {}

        bool TypeFuncGenerator::shouldAutogen() const { return true; };

        void TypeFuncGenerator::genFuncBody( FunctionDecl * dcl ) {
                FunctionType * ftype = dcl->type;
                assertf( ftype->parameters.size() == 1 || ftype->parameters.size() == 2, "Incorrect number of parameters in autogenerated typedecl function: %zd", ftype->parameters.size() );
                DeclarationWithType * dst = ftype->parameters.front();
                DeclarationWithType * src = ftype->parameters.size() == 2 ? ftype->parameters.back() : nullptr;
                // generate appropriate calls to member ctor, assignment
                UntypedExpr * expr = new UntypedExpr( new NameExpr( dcl->name ) );
                expr->args.push_back( new CastExpr( new VariableExpr( dst ), new ReferenceType( Type::Qualifiers(), typeDecl->base->clone() ) ) );
                if ( src ) expr->args.push_back( new CastExpr( new VariableExpr( src ), typeDecl->base->clone() ) );
                dcl->statements->kids.push_back( new ExprStmt( expr ) );
        };

        // xxx - should reach in and determine if base type is concurrent?
        bool TypeFuncGenerator::isConcurrentType() const { return false; };

        // opaque types do not have field constructors
        void TypeFuncGenerator::genFieldCtors() {};

        //=============================================================================================
        // Visitor definitions
        //=============================================================================================
        AutogenerateRoutines::AutogenerateRoutines() {
                // the order here determines the order that these functions are generated.
                // assignment should come last since it uses copy constructor in return.
                data.emplace_back( "?{}", genDefaultType );
                data.emplace_back( "?{}", genCopyType );
                data.emplace_back( "^?{}", genDefaultType );
                data.emplace_back( "?=?", genAssignType );
        }

        void AutogenerateRoutines::previsit( EnumDecl * enumDecl ) {
                // must visit children (enum constants) to add them to the indexer
                if ( enumDecl->has_body() ) {
                        EnumInstType enumInst( Type::Qualifiers(), enumDecl->get_name() );
                        enumInst.set_baseEnum( enumDecl );
                        EnumFuncGenerator gen( &enumInst, data, functionNesting, indexer );
                        generateFunctions( gen, declsToAddAfter );
                }
        }

        void AutogenerateRoutines::previsit( StructDecl * structDecl ) {
                visit_children = false;
                if ( structDecl->has_body() ) {
                        StructInstType structInst( Type::Qualifiers(), structDecl->name );
                        structInst.set_baseStruct( structDecl );
                        for ( TypeDecl * typeDecl : structDecl->parameters ) {
                                structInst.parameters.push_back( new TypeExpr( new TypeInstType( Type::Qualifiers(), typeDecl->name, typeDecl ) ) );
                        }
                        StructFuncGenerator gen( structDecl, &structInst, data, functionNesting, indexer );
                        generateFunctions( gen, declsToAddAfter );
                } // if
        }

        void AutogenerateRoutines::previsit( UnionDecl * unionDecl ) {
                visit_children = false;
                if ( unionDecl->has_body()  ) {
                        UnionInstType unionInst( Type::Qualifiers(), unionDecl->get_name() );
                        unionInst.set_baseUnion( unionDecl );
                        for ( TypeDecl * typeDecl : unionDecl->get_parameters() ) {
                                unionInst.get_parameters().push_back( new TypeExpr( new TypeInstType( Type::Qualifiers(), typeDecl->get_name(), typeDecl ) ) );
                        }
                        UnionFuncGenerator gen( unionDecl, &unionInst, data, functionNesting, indexer );
                        generateFunctions( gen, declsToAddAfter );
                } // if
        }

        // generate ctor/dtors/assign for typedecls, e.g., otype T = int *;
        void AutogenerateRoutines::previsit( TypeDecl * typeDecl ) {
                if ( ! typeDecl->base ) return;

                TypeInstType refType( Type::Qualifiers(), typeDecl->name, typeDecl );
                TypeFuncGenerator gen( typeDecl, &refType, data, functionNesting, indexer );
                generateFunctions( gen, declsToAddAfter );

        }

        void AutogenerateRoutines::previsit( TraitDecl * ) {
                // ensure that we don't add assignment ops for types defined as part of the trait
                visit_children = false;
        }

        void AutogenerateRoutines::previsit( FunctionDecl * ) {
                // Track whether we're currently in a function.
                // Can ignore function type idiosyncrasies, because function type can never
                // declare a new type.
                functionNesting += 1;
                GuardAction( [this]()  { functionNesting -= 1; } );
        }

        void AutogenerateRoutines::previsit( CompoundStmt * ) {
                GuardScope( structsDone );
        }

        void makeTupleFunctionBody( FunctionDecl * function ) {
                FunctionType * ftype = function->get_functionType();
                assertf( ftype->get_parameters().size() == 1 || ftype->get_parameters().size() == 2, "too many parameters in generated tuple function" );

                UntypedExpr * untyped = new UntypedExpr( new NameExpr( function->get_name() ) );

                /// xxx - &* is used to make this easier for later passes to handle
                untyped->get_args().push_back( new AddressExpr( UntypedExpr::createDeref( new VariableExpr( ftype->get_parameters().front() ) ) ) );
                if ( ftype->get_parameters().size() == 2 ) {
                        untyped->get_args().push_back( new VariableExpr( ftype->get_parameters().back() ) );
                }
                function->get_statements()->get_kids().push_back( new ExprStmt( untyped ) );
                function->get_statements()->get_kids().push_back( new ReturnStmt( UntypedExpr::createDeref( new VariableExpr( ftype->get_parameters().front() ) ) ) );
        }

        void AutogenTupleRoutines::postvisit( TupleType * tupleType ) {
                std::string mangleName = SymTab::Mangler::mangleType( tupleType );
                if ( seenTuples.find( mangleName ) != seenTuples.end() ) return;
                seenTuples.insert( mangleName );

                // T ?=?(T *, T);
                FunctionType *assignType = genAssignType( tupleType );

                // void ?{}(T *); void ^?{}(T *);
                FunctionType *ctorType = genDefaultType( tupleType );
                FunctionType *dtorType = genDefaultType( tupleType );

                // void ?{}(T *, T);
                FunctionType *copyCtorType = genCopyType( tupleType );

                std::set< TypeDecl* > done;
                std::list< TypeDecl * > typeParams;
                for ( Type * t : *tupleType ) {
                        if ( TypeInstType * ty = dynamic_cast< TypeInstType * >( t ) ) {
                                if ( ! done.count( ty->get_baseType() ) ) {
                                        TypeDecl * newDecl = new TypeDecl( ty->get_baseType()->get_name(), Type::StorageClasses(), nullptr, TypeDecl::Dtype, true );
                                        TypeInstType * inst = new TypeInstType( Type::Qualifiers(), newDecl->get_name(), newDecl );
                                        newDecl->get_assertions().push_back( new FunctionDecl( "?=?", Type::StorageClasses(), LinkageSpec::Cforall, genAssignType( inst ), nullptr,
                                                                                                                                                   std::list< Attribute * >(), Type::FuncSpecifiers( Type::Inline ) ) );
                                        newDecl->get_assertions().push_back( new FunctionDecl( "?{}", Type::StorageClasses(), LinkageSpec::Cforall, genDefaultType( inst ), nullptr,
                                                                                                                                                   std::list< Attribute * >(), Type::FuncSpecifiers( Type::Inline ) ) );
                                        newDecl->get_assertions().push_back( new FunctionDecl( "?{}", Type::StorageClasses(), LinkageSpec::Cforall, genCopyType( inst ), nullptr,
                                                                                                                                                   std::list< Attribute * >(), Type::FuncSpecifiers( Type::Inline ) ) );
                                        newDecl->get_assertions().push_back( new FunctionDecl( "^?{}", Type::StorageClasses(), LinkageSpec::Cforall, genDefaultType( inst ), nullptr,
                                                                                                                                                   std::list< Attribute * >(), Type::FuncSpecifiers( Type::Inline ) ) );
                                        typeParams.push_back( newDecl );
                                        done.insert( ty->get_baseType() );
                                }
                        }
                }
                cloneAll( typeParams, ctorType->get_forall() );
                cloneAll( typeParams, dtorType->get_forall() );
                cloneAll( typeParams, copyCtorType->get_forall() );
                cloneAll( typeParams, assignType->get_forall() );

                FunctionDecl *assignDecl = genFunc( "?=?", assignType, functionNesting );
                FunctionDecl *ctorDecl = genFunc( "?{}", ctorType, functionNesting );
                FunctionDecl *copyCtorDecl = genFunc( "?{}", copyCtorType, functionNesting );
                FunctionDecl *dtorDecl = genFunc( "^?{}", dtorType, functionNesting );

                makeTupleFunctionBody( assignDecl );
                makeTupleFunctionBody( ctorDecl );
                makeTupleFunctionBody( copyCtorDecl );
                makeTupleFunctionBody( dtorDecl );

                declsToAddBefore.push_back( ctorDecl );
                declsToAddBefore.push_back( copyCtorDecl );
                declsToAddBefore.push_back( dtorDecl );
                declsToAddBefore.push_back( assignDecl ); // assignment should come last since it uses copy constructor in return
        }

        void AutogenTupleRoutines::previsit( FunctionDecl *functionDecl ) {
                visit_children = false;
                maybeAccept( functionDecl->type, *visitor );
                functionNesting += 1;
                maybeAccept( functionDecl->statements, *visitor );
                functionNesting -= 1;
        }

        void AutogenTupleRoutines::previsit( CompoundStmt * ) {
                GuardScope( seenTuples );
        }
} // SymTab

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