source: src/InitTweak/GenInit.cc @ 7baed7d

//
// 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.
//
// GenInit.cc --
//
// Author           : Rob Schluntz
// Created On       : Mon May 18 07:44:20 2015
// Last Modified By : Rob Schluntz
// Last Modified On : Fri May 13 11:37:48 2016
// Update Count     : 166
//

#include <stack>
#include <list>
#include "GenInit.h"
#include "InitTweak.h"
#include "SynTree/Declaration.h"
#include "SynTree/Type.h"
#include "SynTree/Expression.h"
#include "SynTree/Statement.h"
#include "SynTree/Initializer.h"
#include "SynTree/Mutator.h"
#include "SymTab/Autogen.h"
#include "GenPoly/PolyMutator.h"

namespace InitTweak {
        namespace {
                const std::list<Label> noLabels;
                const std::list<Expression *> noDesignators;
        }

        class ReturnFixer : public GenPoly::PolyMutator {
          public:
                /// consistently allocates a temporary variable for the return value
                /// of a function so that anything which the resolver decides can be constructed
                /// into the return type of a function can be returned.
                static void makeReturnTemp( std::list< Declaration * > &translationUnit );

                ReturnFixer();

                virtual DeclarationWithType * mutate( FunctionDecl *functionDecl );

                virtual Statement * mutate( ReturnStmt * returnStmt );

          protected:
                std::list<DeclarationWithType*> returnVals;
                UniqueName tempNamer;
                std::string funcName;
        };

        class CtorDtor : public GenPoly::PolyMutator {
          public:
                /// create constructor and destructor statements for object declarations.
                /// Destructors are inserted directly into the code, whereas constructors
                /// will be added in after the resolver has run so that the initializer expression
                /// is only removed if a constructor is found
                static void generateCtorDtor( std::list< Declaration * > &translationUnit );

                CtorDtor() : inFunction( false ) {}

                virtual DeclarationWithType * mutate( ObjectDecl * );
                virtual DeclarationWithType * mutate( FunctionDecl *functionDecl );
                virtual Declaration* mutate( StructDecl *aggregateDecl );
                virtual Declaration* mutate( UnionDecl *aggregateDecl );
                virtual Declaration* mutate( EnumDecl *aggregateDecl );
                virtual Declaration* mutate( TraitDecl *aggregateDecl );
                virtual TypeDecl* mutate( TypeDecl *typeDecl );
                virtual Declaration* mutate( TypedefDecl *typeDecl );

                virtual Type * mutate( FunctionType *funcType );

          protected:
                bool inFunction;
        };

        void genInit( std::list< Declaration * > & translationUnit ) {
                ReturnFixer::makeReturnTemp( translationUnit );
                CtorDtor::generateCtorDtor( translationUnit );
        }

        void ReturnFixer::makeReturnTemp( std::list< Declaration * > & translationUnit ) {
                ReturnFixer fixer;
                mutateAll( translationUnit, fixer );
        }

        ReturnFixer::ReturnFixer() : tempNamer( "_retVal" ) {}

        Statement *ReturnFixer::mutate( ReturnStmt *returnStmt ) {
                // update for multiple return values
                assert( returnVals.size() == 0 || returnVals.size() == 1 );
                // hands off if the function returns an lvalue - we don't want to allocate a temporary if a variable's address
                // is being returned
                if ( returnStmt->get_expr() && returnVals.size() == 1 && funcName != "?=?" && ! returnVals.front()->get_type()->get_isLvalue() ) {
                        // ensure return value is not destructed by explicitly creating
                        // an empty SingleInit node wherein maybeConstruct is false
                        ObjectDecl *newObj = new ObjectDecl( tempNamer.newName(), DeclarationNode::NoStorageClass, LinkageSpec::C, 0, returnVals.front()->get_type()->clone(), new ListInit( std::list<Initializer*>(), noDesignators, false ) );
                        stmtsToAdd.push_back( new DeclStmt( noLabels, newObj ) );

                        // and explicitly create the constructor expression separately
                        UntypedExpr *construct = new UntypedExpr( new NameExpr( "?{}" ) );
                        construct->get_args().push_back( new AddressExpr( new VariableExpr( newObj ) ) );
                        construct->get_args().push_back( returnStmt->get_expr() );
                        stmtsToAdd.push_back(new ExprStmt(noLabels, construct));

                        returnStmt->set_expr( new VariableExpr( newObj ) );
                } // if
                return returnStmt;
        }

        DeclarationWithType* ReturnFixer::mutate( FunctionDecl *functionDecl ) {
                std::list<DeclarationWithType*> oldReturnVals = returnVals;
                std::string oldFuncName = funcName;

                FunctionType * type = functionDecl->get_functionType();
                returnVals = type->get_returnVals();
                funcName = functionDecl->get_name();
                DeclarationWithType * decl = Mutator::mutate( functionDecl );
                returnVals = oldReturnVals;
                funcName = oldFuncName;
                return decl;
        }


        void CtorDtor::generateCtorDtor( std::list< Declaration * > & translationUnit ) {
                CtorDtor ctordtor;
                mutateAll( translationUnit, ctordtor );
        }

        namespace {
                Expression * makeCtorDtorExpr( std::string name, ObjectDecl * objDecl, std::list< Expression * > args ) {
                        UntypedExpr * expr = new UntypedExpr( new NameExpr( name ) );
                        expr->get_args().push_back( new AddressExpr( new VariableExpr( objDecl ) ) );
                        expr->get_args().splice( expr->get_args().end(), args );
                        return expr;
                }
        }

        DeclarationWithType * CtorDtor::mutate( ObjectDecl * objDecl ) {
                // hands off if designated or if @=
                if ( tryConstruct( objDecl ) ) {
                        if ( inFunction ) {
                                if ( ArrayType * at = dynamic_cast< ArrayType * >( objDecl->get_type() ) ) {
                                        // call into makeArrayFunction from validate.cc to generate calls to ctor/dtor for each element of array
                                        // TODO: walk initializer and generate appropriate copy ctor if element has initializer
                                        std::list< Expression * > args = makeInitList( objDecl->get_init() );
                                        if ( args.empty() ) {
                                                std::list< Statement * > ctor;
                                                std::list< Statement * > dtor;

                                                SymTab::makeArrayFunction( NULL, new VariableExpr( objDecl ), at, "?{}", back_inserter( ctor ) );
                                                SymTab::makeArrayFunction( NULL, new VariableExpr( objDecl ), at, "^?{}", front_inserter( dtor ), false );

                                                // Currently makeArrayFunction produces a single Statement - a CompoundStmt
                                                // which  wraps everything that needs to happen. As such, it's technically
                                                // possible to use a Statement ** in the above calls, but this is inherently
                                                // unsafe, so instead we take the slightly less efficient route, but will be
                                                // immediately informed if somehow the above assumption is broken. In this case,
                                                // we could always wrap the list of statements at this point with a CompoundStmt,
                                                // but it seems reasonable at the moment for this to be done by makeArrayFunction
                                                // itself
                                                assert( ctor.size() == 1 );
                                                assert( dtor.size() == 1 );
                                                objDecl->set_init( new ConstructorInit( new ImplicitCtorDtorStmt( ctor.front() ), new ImplicitCtorDtorStmt( dtor.front() ), objDecl->get_init() ) );
                                        } else {
                                                // array came with an initializer list: initialize each element
                                                // may have more initializers than elements in the array - need to check at each index that
                                                // we haven't exceeded size. This requires precomputing the size because it might be a side-effecting
                                                // computation.
                                                // may have fewer initializers than eleemnts in the array - need to default construct
                                                // remaining elements.
                                                // might be able to merge this with the case above.
                                        }
                                } else {
                                        // it's sufficient to attempt to call the ctor/dtor for the given object and its initializer
                                        Expression * ctor = makeCtorDtorExpr( "?{}", objDecl, makeInitList( objDecl->get_init() ) );
                                        Expression * dtor = makeCtorDtorExpr( "^?{}", objDecl, std::list< Expression * >() );

                                        // need to remember init expression, in case no ctors exist
                                        // if ctor does exist, want to use ctor expression instead of init
                                        // push this decision to the resolver
                                        ExprStmt * ctorStmt = new ExprStmt( noLabels, ctor );
                                        ExprStmt * dtorStmt = new ExprStmt( noLabels, dtor );
                                        objDecl->set_init( new ConstructorInit( new ImplicitCtorDtorStmt( ctorStmt ), new ImplicitCtorDtorStmt( dtorStmt ), objDecl->get_init() ) );
                                }
                        }
                }
                return Mutator::mutate( objDecl );
        }

        DeclarationWithType * CtorDtor::mutate( FunctionDecl *functionDecl ) {
                // parameters should not be constructed and destructed, so don't mutate FunctionType
                bool oldInFunc = inFunction;
                mutateAll( functionDecl->get_oldDecls(), *this );
                inFunction = true;
                functionDecl->set_statements( maybeMutate( functionDecl->get_statements(), *this ) );
                inFunction = oldInFunc;
                return functionDecl;
        }

        // should not traverse into any of these declarations to find objects
        // that need to be constructed or destructed
        Declaration* CtorDtor::mutate( StructDecl *aggregateDecl ) { return aggregateDecl; }
        Declaration* CtorDtor::mutate( UnionDecl *aggregateDecl ) { return aggregateDecl; }
        Declaration* CtorDtor::mutate( EnumDecl *aggregateDecl ) { return aggregateDecl; }
        Declaration* CtorDtor::mutate( TraitDecl *aggregateDecl ) { return aggregateDecl; }
        TypeDecl* CtorDtor::mutate( TypeDecl *typeDecl ) { return typeDecl; }
        Declaration* CtorDtor::mutate( TypedefDecl *typeDecl ) { return typeDecl; }
        Type* CtorDtor::mutate( FunctionType *funcType ) { return funcType; }

} // namespace InitTweak

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