source: src/SymTab/Autogen.cc @ 60c3b06c

//
// 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 : Andrew Beach
// Last Modified On : Fri Jul 14 16:41:00 2017
// Update Count     : 62
//

#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 "AddVisit.h"              // for addVisit
#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/DeclMutator.h"   // for DeclMutator
#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

class Attribute;

namespace SymTab {
        Type * SizeType = 0;
        typedef ScopedMap< std::string, bool > TypeMap;

        /// Data used to generate functions generically. Specifically, the name of the generated function, a function which generates the routine protoype, and a map which contains data to determine whether a function should be generated.
        struct FuncData {
                typedef FunctionType * (*TypeGen)( Type * );
                FuncData( const std::string & fname, const TypeGen & genType, TypeMap & map ) : fname( fname ), genType( genType ), map( map ) {}
                std::string fname;
                TypeGen genType;
                TypeMap & map;
        };

        struct AutogenerateRoutines final : public WithDeclsToAdd, public WithVisitorRef<AutogenerateRoutines>, public WithGuards, public WithShortCircuiting {
                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( FunctionType * ftype );
                void previsit( PointerType * ptype );

                void previsit( CompoundStmt * compoundStmt );

          private:
                GenPoly::ScopedSet< std::string > structsDone;
                unsigned int functionNesting = 0;     // current level of nested functions
                /// Note: the following maps could be ScopedSets, but it should be easier to work
                /// deleted functions in if they are maps, since the value false can be inserted
                /// at the current scope without affecting outer scopes or requiring copies.
                TypeMap copyable, assignable, constructable, destructable;
                std::vector< FuncData > data;
        };

        /// generates routines for tuple types.
        /// Doesn't really need to be a mutator, but it's easier to reuse DeclMutator than it is to use AddVisit
        /// or anything we currently have that supports adding new declarations for visitors
        class AutogenTupleRoutines : public GenPoly::DeclMutator {
          public:
                typedef GenPoly::DeclMutator Parent;
                using Parent::mutate;

                virtual DeclarationWithType * mutate( FunctionDecl *functionDecl );

                virtual Type * mutate( TupleType *tupleType );

                virtual CompoundStmt * mutate( 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;
                // tupleGenerator.mutateDeclarationList( translationUnit );
        }

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

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

        /// given type T, generate type of default ctor/dtor, i.e. function type void (*) (T *)
        FunctionType * genDefaultType( Type * paramType ) {
                FunctionType *ftype = new FunctionType( Type::Qualifiers(), false );
                ObjectDecl *dstParam = new ObjectDecl( "_dst", Type::StorageClasses(), LinkageSpec::Cforall, nullptr, new ReferenceType( Type::Qualifiers(), paramType->clone() ), nullptr );
                ftype->get_parameters().push_back( dstParam );

                return ftype;
        }

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

        /// given type T, generate type of assignment, i.e. function type T (*) (T *, T)
        FunctionType * genAssignType( Type * paramType ) {
                FunctionType *ftype = genCopyType( paramType );
                ObjectDecl *returnVal = new ObjectDecl( "_ret", Type::StorageClasses(), LinkageSpec::Cforall, nullptr, paramType->clone(), nullptr );
                ftype->get_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( noLabels ),
                                                                                                std::list< Attribute * >(), Type::FuncSpecifiers( Type::Inline ) );
                decl->fixUniqueId();
                return decl;
        }

        /// inserts base type of first argument into map if pred(funcDecl) is true
        void insert( FunctionDecl *funcDecl, TypeMap & map, FunctionDecl * (*pred)(Declaration *) ) {
                // insert type into constructable, etc. map if appropriate
                if ( pred( funcDecl ) ) {
                        FunctionType * ftype = funcDecl->get_functionType();
                        assert( ! ftype->get_parameters().empty() );
                        Type * t = InitTweak::getPointerBase( ftype->get_parameters().front()->get_type() );
                        assert( t );
                        map.insert( Mangler::mangleType( t ), true );
                }
        }

        /// using map and t, determines if is constructable, etc.
        bool lookup( const TypeMap & map, Type * t ) {
                assertf( t, "Autogenerate lookup was given non-type: %s", toString( t ).c_str() );
                if ( dynamic_cast< PointerType * >( t ) ) {
                        // will need more complicated checking if we want this to work with pointer types, since currently
                        return true;
                } else if ( ArrayType * at = dynamic_cast< ArrayType * >( t ) ) {
                        // an array's constructor, etc. is generated on the fly based on the base type's constructor, etc.
                        return lookup( map, at->get_base() );
                }
                TypeMap::const_iterator it = map.find( Mangler::mangleType( t ) );
                if ( it != map.end() ) return it->second;
                // something that does not appear in the map is by default not constructable, etc.
                return false;
        }

        /// using map and aggr, examines each member to determine if constructor, etc. should be generated
        template<typename Container>
        bool shouldGenerate( const TypeMap & map, const Container & container ) {
                for ( Type * t : container ) {
                        if ( ! lookup( map, t ) ) return false;
                }
                return true;
        }

        /// data structure for abstracting the generation of special functions
        template< typename OutputIterator, typename Container >
        struct FuncGenerator {
                const Container & container;
                Type *refType;
                unsigned int functionNesting;
                const std::list< TypeDecl* > & typeParams;
                OutputIterator out;
                FuncGenerator( const Container & container, Type *refType, unsigned int functionNesting, const std::list< TypeDecl* > & typeParams, OutputIterator out ) : container( container ), refType( refType ), functionNesting( functionNesting ), typeParams( typeParams ), out( out ) {}

                /// generates a function (?{}, ?=?, ^?{}) based on the data argument and members. If function is generated, inserts the type into the map.
                void gen( const FuncData & data, bool concurrent_type ) {
                        if ( ! shouldGenerate( data.map, container ) ) return;
                        FunctionType * ftype = data.genType( refType );

                        if ( concurrent_type && CodeGen::isDestructor( data.fname ) ) {
                                ftype->parameters.front()->get_type()->set_mutex( true );
                        }

                        cloneAll( typeParams, ftype->forall );
                        *out++ = genFunc( data.fname, ftype, functionNesting );
                        data.map.insert( Mangler::mangleType( refType ), true );
                }
        };

        template< typename OutputIterator, typename Container >
        FuncGenerator<OutputIterator, Container> makeFuncGenerator( const Container & container, Type *refType, unsigned int functionNesting, const std::list< TypeDecl* > & typeParams, OutputIterator out ) {
                return FuncGenerator<OutputIterator, Container>( container, refType, functionNesting, typeParams, out );
        }

        /// generates a single enumeration assignment expression
        ApplicationExpr * genEnumAssign( FunctionType * ftype, FunctionDecl * assignDecl ) {
                // 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
                // NOTE: ftype is not necessarily the functionType belonging to assignDecl - ftype is the
                // type of the function that this expression is being generated for (so that the correct
                // parameters) are using in the variable exprs
                assert( ftype->get_parameters().size() == 2 );
                ObjectDecl * dstParam = strict_dynamic_cast< ObjectDecl * >( ftype->get_parameters().front() );
                ObjectDecl * srcParam = strict_dynamic_cast< ObjectDecl * >( ftype->get_parameters().back() );

                VariableExpr * assignVarExpr = new VariableExpr( assignDecl );
                Type * assignVarExprType = assignVarExpr->get_result();
                assignVarExprType = new PointerType( Type::Qualifiers(), assignVarExprType );
                assignVarExpr->set_result( assignVarExprType );
                ApplicationExpr * assignExpr = new ApplicationExpr( assignVarExpr );
                assignExpr->get_args().push_back( new VariableExpr( dstParam ) );
                assignExpr->get_args().push_back( new VariableExpr( srcParam ) );
                return assignExpr;
        }

        // E ?=?(E volatile*, int),
        //   ?=?(E _Atomic volatile*, int);
        void makeEnumFunctions( EnumInstType *refType, unsigned int functionNesting, std::list< Declaration * > &declsToAdd ) {

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

                // void ?{}(E *); void ^?{}(E *);
                FunctionType * ctorType = genDefaultType( refType->clone() );
                FunctionType * dtorType = genDefaultType( refType->clone() );

                // void ?{}(E *, E);
                FunctionType *copyCtorType = genCopyType( refType->clone() );

                // add unused attribute to parameters of default constructor and destructor
                ctorType->get_parameters().front()->get_attributes().push_back( new Attribute( "unused" ) );
                dtorType->get_parameters().front()->get_attributes().push_back( new Attribute( "unused" ) );

                // xxx - should we also generate void ?{}(E *, int) and E ?{}(E *, E)?
                // right now these cases work, but that might change.

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

                // body is either return stmt or expr stmt
                assignDecl->get_statements()->get_kids().push_back( new ReturnStmt( noLabels, genEnumAssign( assignType, assignDecl ) ) );
                copyCtorDecl->get_statements()->get_kids().push_back( new ExprStmt( noLabels, genEnumAssign( copyCtorType, assignDecl ) ) );

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

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

                // assign to destination
                Expression *dstselect = new MemberExpr( field, new CastExpr( new VariableExpr( dstParam ), strict_dynamic_cast< ReferenceType* >( dstParam->get_type() )->get_base()->clone() ) );
                genImplicitCall( srcParam, dstselect, func->get_name(), back_inserter( func->get_statements()->get_kids() ), field, forward );
        }

        /// 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 makeStructFunctionBody( Iterator member, Iterator end, FunctionDecl * func, bool forward = true ) {
                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() && func->get_name() == "?=?" ) {
                                        // don't assign const members, but do construct/destruct
                                        continue;
                                }

                                if ( field->get_name() == "" ) {
                                        // don't assign to anonymous members
                                        // xxx - this is a temporary fix. Anonymous members tie into
                                        // our inheritance model. I think the correct way to handle this is to
                                        // cast the structure to the type of the member and let the resolver
                                        // figure out whether it's valid and have a pass afterwards that fixes
                                        // the assignment to use pointer arithmetic with the offset of the
                                        // member, much like how generic type members are handled.
                                        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;
                                makeStructMemberOp( dstParam, srcselect, field, func, forward );
                        } // if
                } // for
        } // makeStructFunctionBody

        /// 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 makeStructFieldCtorBody( Iterator member, Iterator end, FunctionDecl * func ) {
                FunctionType * ftype = func->get_functionType();
                std::list<DeclarationWithType*> & params = ftype->get_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 ( field->get_name() == "" ) {
                                        // don't assign to anonymous members
                                        // xxx - this is a temporary fix. Anonymous members tie into
                                        // our inheritance model. I think the correct way to handle this is to
                                        // cast the structure to the type of the member and let the resolver
                                        // figure out whether it's valid and have a pass afterwards that fixes
                                        // the assignment to use pointer arithmetic with the offset of the
                                        // member, much like how generic type members are handled.
                                        continue;
                                } else if ( parameter != params.end() ) {
                                        // matching parameter, initialize field with copy ctor
                                        Expression *srcselect = new VariableExpr(*parameter);
                                        makeStructMemberOp( dstParam, srcselect, field, func );
                                        ++parameter;
                                } else {
                                        // no matching parameter, initialize field with default ctor
                                        makeStructMemberOp( dstParam, nullptr, field, func );
                                }
                        }
                }
        }

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

        /// generates struct constructors, destructor, and assignment functions
        void makeStructFunctions( StructDecl *aggregateDecl, StructInstType *refType, unsigned int functionNesting, std::list< Declaration * > & declsToAdd, const std::vector< FuncData > & data ) {
                // Builtins do not use autogeneration.
                if ( LinkageSpec::isBuiltin( aggregateDecl->get_linkage() ) ) {
                        return;
                }

                // Make function polymorphic in same parameters as generic struct, if applicable
                const std::list< TypeDecl * > & typeParams = aggregateDecl->get_parameters(); // List of type variables to be placed on the generated functions

                // generate each of the functions based on the supplied FuncData objects
                std::list< FunctionDecl * > newFuncs;
                // structure that iterates aggregate decl members, returning their types
                auto generator = makeFuncGenerator( lazy_map( aggregateDecl->members, declToType ), refType, functionNesting, typeParams, back_inserter( newFuncs ) );
                for ( const FuncData & d : data ) {
                        generator.gen( d, aggregateDecl->is_thread() || aggregateDecl->is_monitor() );
                }

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

                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.
                        for ( FunctionDecl * dcl : newFuncs ) {
                                addForwardDecl( dcl, declsToAdd );
                        }
                }

                for ( FunctionDecl * dcl : newFuncs ) {
                        // 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->get_name() ) ) {
                                makeStructFunctionBody( aggregateDecl->get_members().begin(), aggregateDecl->get_members().end(), dcl );
                        } else {
                                makeStructFunctionBody( aggregateDecl->get_members().rbegin(), aggregateDecl->get_members().rend(), dcl, false );
                        }
                        if ( CodeGen::isAssignment( dcl->get_name() ) ) {
                                // assignment needs to return a value
                                FunctionType * assignType = dcl->get_functionType();
                                assert( assignType->get_parameters().size() == 2 );
                                ObjectDecl * srcParam = strict_dynamic_cast< ObjectDecl * >( assignType->get_parameters().back() );
                                dcl->get_statements()->get_kids().push_back( new ReturnStmt( noLabels, new VariableExpr( srcParam ) ) );
                        }
                        declsToAdd.push_back( dcl );
                }

                // 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)
                // Field constructors are only generated if default and copy constructor
                // are generated, since they need access to both
                if ( numCtors == 2 ) {
                        FunctionType * memCtorType = genDefaultType( refType );
                        cloneAll( typeParams, memCtorType->get_forall() );
                        for ( std::list<Declaration *>::iterator i = aggregateDecl->get_members().begin(); i != aggregateDecl->get_members().end(); ++i ) {
                                DeclarationWithType * member = dynamic_cast<DeclarationWithType *>( *i );
                                assert( member );
                                if ( isUnnamedBitfield( dynamic_cast< ObjectDecl * > ( member ) ) ) {
                                        // don't make a function whose parameter is an unnamed bitfield
                                        continue;
                                } else if ( member->get_name() == "" ) {
                                        // don't assign to anonymous members
                                        // xxx - this is a temporary fix. Anonymous members tie into
                                        // our inheritance model. I think the correct way to handle this is to
                                        // cast the structure to the type of the member and let the resolver
                                        // figure out whether it's valid/choose the correct unnamed member
                                        continue;
                                }
                                memCtorType->get_parameters().push_back( new ObjectDecl( member->get_name(), Type::StorageClasses(), LinkageSpec::Cforall, 0, member->get_type()->clone(), 0 ) );
                                FunctionDecl * ctor = genFunc( "?{}", memCtorType->clone(), functionNesting );
                                makeStructFieldCtorBody( aggregateDecl->get_members().begin(), aggregateDecl->get_members().end(), ctor );
                                declsToAdd.push_back( ctor );
                        }
                        delete memCtorType;
                }
        }

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

        /// generates the body of a union assignment/copy constructor/field constructor
        void makeUnionAssignBody( FunctionDecl * funcDecl ) {
                FunctionType * ftype = funcDecl->get_functionType();
                assert( ftype->get_parameters().size() == 2 );
                ObjectDecl * dstParam = strict_dynamic_cast< ObjectDecl * >( ftype->get_parameters().front() );
                ObjectDecl * srcParam = strict_dynamic_cast< ObjectDecl * >( ftype->get_parameters().back() );

                makeUnionFieldsAssignment( srcParam, dstParam, back_inserter( funcDecl->get_statements()->get_kids() ) );
                if ( CodeGen::isAssignment( funcDecl->get_name() ) ) {
                        // also generate return statement in assignment
                        funcDecl->get_statements()->get_kids().push_back( new ReturnStmt( noLabels, new VariableExpr( srcParam ) ) );
                }
        }

        /// generates union constructors, destructors, and assignment operator
        void makeUnionFunctions( UnionDecl *aggregateDecl, UnionInstType *refType, unsigned int functionNesting, std::list< Declaration * > & declsToAdd ) {
                // Make function polymorphic in same parameters as generic union, if applicable
                const std::list< TypeDecl* > & typeParams = aggregateDecl->get_parameters(); // List of type variables to be placed on the generated functions

                // default ctor/dtor need only first parameter
                // void ?{}(T *); void ^?{}(T *);
                FunctionType *ctorType = genDefaultType( refType );
                FunctionType *dtorType = genDefaultType( refType );

                // copy ctor needs both parameters
                // void ?{}(T *, T);
                FunctionType *copyCtorType = genCopyType( refType );

                // assignment needs both and return value
                // T ?=?(T *, T);
                FunctionType *assignType = genAssignType( refType );

                cloneAll( typeParams, ctorType->get_forall() );
                cloneAll( typeParams, dtorType->get_forall() );
                cloneAll( typeParams, copyCtorType->get_forall() );
                cloneAll( typeParams, assignType->get_forall() );

                // add unused attribute to parameters of default constructor and destructor
                ctorType->get_parameters().front()->get_attributes().push_back( new Attribute( "unused" ) );
                dtorType->get_parameters().front()->get_attributes().push_back( new Attribute( "unused" ) );

                // Routines at global scope marked "static" to prevent multiple definitions is separate translation units
                // because each unit generates copies of the default routines for each aggregate.
                FunctionDecl *assignDecl = genFunc( "?=?", assignType, functionNesting );
                FunctionDecl *ctorDecl = genFunc( "?{}",  ctorType, functionNesting );
                FunctionDecl *copyCtorDecl = genFunc( "?{}", copyCtorType, functionNesting );
                FunctionDecl *dtorDecl = genFunc( "^?{}", dtorType, functionNesting );

                makeUnionAssignBody( assignDecl );

                // body of assignment and copy ctor is the same
                makeUnionAssignBody( copyCtorDecl );

                // 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.
                std::list<Declaration *> memCtors;
                for ( Declaration * member : aggregateDecl->get_members() ) {
                        if ( DeclarationWithType * field = dynamic_cast< DeclarationWithType * >( member ) ) {
                                ObjectDecl * srcParam = new ObjectDecl( "src", Type::StorageClasses(), LinkageSpec::Cforall, 0, field->get_type()->clone(), 0 );

                                FunctionType * memCtorType = ctorType->clone();
                                memCtorType->get_parameters().push_back( srcParam );
                                FunctionDecl * ctor = genFunc( "?{}", memCtorType, functionNesting );

                                makeUnionAssignBody( ctor );
                                memCtors.push_back( ctor );
                                // only generate a ctor for the first field
                                break;
                        }
                }

                declsToAdd.push_back( ctorDecl );
                declsToAdd.push_back( copyCtorDecl );
                declsToAdd.push_back( dtorDecl );
                declsToAdd.push_back( assignDecl ); // assignment should come last since it uses copy constructor in return
                declsToAdd.splice( declsToAdd.end(), memCtors );
        }

        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, constructable );
                data.emplace_back( "?{}", genCopyType, copyable );
                data.emplace_back( "^?{}", genDefaultType, destructable );
                data.emplace_back( "?=?", genAssignType, assignable );
        }

        void AutogenerateRoutines::previsit( EnumDecl * enumDecl ) {
                visit_children = false;
                if ( ! enumDecl->get_members().empty() ) {
                        EnumInstType *enumInst = new EnumInstType( Type::Qualifiers(), enumDecl->get_name() );
                        // enumInst->set_baseEnum( enumDecl );
                        makeEnumFunctions( enumInst, functionNesting, declsToAddAfter );
                }
        }

        void AutogenerateRoutines::previsit( StructDecl * structDecl ) {
                visit_children = false;
                if ( structDecl->has_body() && structsDone.find( structDecl->name ) == structsDone.end() ) {
                        StructInstType structInst( Type::Qualifiers(), structDecl->name );
                        for ( TypeDecl * typeDecl : structDecl->parameters ) {
                                // need to visit assertions so that they are added to the appropriate maps
                                acceptAll( typeDecl->assertions, *visitor );
                                structInst.parameters.push_back( new TypeExpr( new TypeInstType( Type::Qualifiers(), typeDecl->name, typeDecl ) ) );
                        }
                        structInst.set_baseStruct( structDecl );
                        makeStructFunctions( structDecl, &structInst, functionNesting, declsToAddAfter, data );
                        structsDone.insert( structDecl->name );
                } // if
        }

        void AutogenerateRoutines::previsit( UnionDecl * unionDecl ) {
                visit_children = false;
                if ( ! unionDecl->get_members().empty() ) {
                        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 ) ) );
                        }
                        makeUnionFunctions( unionDecl, &unionInst, functionNesting, declsToAddAfter );
                } // if
        }

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

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

                // generate each of the functions based on the supplied FuncData objects
                std::list< FunctionDecl * > newFuncs;
                std::list< Declaration * > tds { typeDecl };
                std::list< TypeDecl * > typeParams;
                TypeInstType refType( Type::Qualifiers(), typeDecl->name, typeDecl );
                auto generator = makeFuncGenerator( lazy_map( tds, declToTypeDeclBase ), &refType, functionNesting, typeParams, back_inserter( newFuncs ) );
                for ( const FuncData & d : data ) {
                        generator.gen( d, false );
                }

                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.
                        for ( FunctionDecl * dcl : newFuncs ) {
                                addForwardDecl( dcl, declsToAddAfter );
                        }
                }

                for ( FunctionDecl * dcl : newFuncs ) {
                        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
                        // destructor needs to do everything in reverse, so pass "forward" based on whether the function is a destructor
                        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( noLabels, expr ) );
                        if ( CodeGen::isAssignment( dcl->get_name() ) ) {
                                // assignment needs to return a value
                                FunctionType * assignType = dcl->type;
                                assert( assignType->parameters.size() == 2 );
                                ObjectDecl * srcParam = strict_dynamic_cast< ObjectDecl * >( assignType->parameters.back() );
                                dcl->statements->kids.push_back( new ReturnStmt( noLabels, new VariableExpr( srcParam ) ) );
                        }
                        declsToAddAfter.push_back( dcl );
                }
        }

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

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

        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 * functionDecl ) {
                visit_children = false;
                // record the existence of this function as appropriate
                insert( functionDecl, constructable, InitTweak::isDefaultConstructor );
                insert( functionDecl, assignable, InitTweak::isAssignment );
                insert( functionDecl, copyable, InitTweak::isCopyConstructor );
                insert( functionDecl, destructable, InitTweak::isDestructor );

                maybeAccept( functionDecl->type, *visitor );
                functionNesting += 1;
                maybeAccept( functionDecl->statements, *visitor );
                functionNesting -= 1;
        }

        void AutogenerateRoutines::previsit( CompoundStmt * ) {
                GuardScope( constructable );
                GuardScope( assignable );
                GuardScope( copyable );
                GuardScope( destructable );
                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( noLabels, untyped ) );
                function->get_statements()->get_kids().push_back( new ReturnStmt( noLabels, UntypedExpr::createDeref( new VariableExpr( ftype->get_parameters().front() ) ) ) );
        }

        Type * AutogenTupleRoutines::mutate( TupleType * tupleType ) {
                tupleType = strict_dynamic_cast< TupleType * >( Parent::mutate( tupleType ) );
                std::string mangleName = SymTab::Mangler::mangleType( tupleType );
                if ( seenTuples.find( mangleName ) != seenTuples.end() ) return tupleType;
                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::Any );
                                        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 );

                addDeclaration( ctorDecl );
                addDeclaration( copyCtorDecl );
                addDeclaration( dtorDecl );
                addDeclaration( assignDecl ); // assignment should come last since it uses copy constructor in return

                return tupleType;
        }

        DeclarationWithType * AutogenTupleRoutines::mutate( FunctionDecl *functionDecl ) {
                functionDecl->set_functionType( maybeMutate( functionDecl->get_functionType(), *this ) );
                functionNesting += 1;
                functionDecl->set_statements( maybeMutate( functionDecl->get_statements(), *this ) );
                functionNesting -= 1;
                return functionDecl;
        }

        CompoundStmt * AutogenTupleRoutines::mutate( CompoundStmt *compoundStmt ) {
                seenTuples.beginScope();
                compoundStmt = strict_dynamic_cast< CompoundStmt * >( Parent::mutate( compoundStmt ) );
                seenTuples.endScope();
                return compoundStmt;
        }
} // SymTab

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