source: src/CodeGen/CodeGenerator.cc @ ca26509

//
// 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.
//
// CodeGenerator.cc --
//
// Author           : Richard C. Bilson
// Created On       : Mon May 18 07:44:20 2015
// Last Modified By : Peter A. Buhr
// Last Modified On : Thu Jun  9 13:21:00 2016
// Update Count     : 256
//

#include <algorithm>
#include <iostream>
#include <cassert>
#include <list>

#include "Parser/ParseNode.h"

#include "SynTree/Declaration.h"
#include "SynTree/Expression.h"
#include "SynTree/Initializer.h"
#include "SynTree/Statement.h"
#include "SynTree/Type.h"
#include "SynTree/Attribute.h"

#include "Common/utility.h"
#include "Common/UnimplementedError.h"

#include "CodeGenerator.h"
#include "OperatorTable.h"
#include "GenType.h"

#include "InitTweak/InitTweak.h"

using namespace std;

namespace CodeGen {
        int CodeGenerator::tabsize = 4;

        // the kinds of statements that would ideally be followed by whitespace
        bool wantSpacing( Statement * stmt) {
                return dynamic_cast< IfStmt * >( stmt ) || dynamic_cast< CompoundStmt * >( stmt ) ||
                        dynamic_cast< WhileStmt * >( stmt ) || dynamic_cast< ForStmt * > ( stmt ) || dynamic_cast< SwitchStmt *>( stmt );
        }

        ostream & CodeGenerator::Indenter::operator()( ostream & output ) {
          return output << string( cg.cur_indent, ' ' );
        }

        ostream & operator<<( ostream & output, CodeGenerator::Indenter &indent ) {
                return indent( output );
        }

        CodeGenerator::CodeGenerator( std::ostream &os ) : indent( *this), cur_indent( 0 ), insideFunction( false ), output( os ) { }

        CodeGenerator::CodeGenerator( std::ostream &os, std::string init, int indentation, bool infunp )
                        : indent( *this), cur_indent( indentation ), insideFunction( infunp ), output( os ) {
                //output << std::string( init );
        }

        CodeGenerator::CodeGenerator( std::ostream &os, char *init, int indentation, bool infunp )
                        : indent( *this ), cur_indent( indentation ), insideFunction( infunp ), output( os ) {
                //output << std::string( init );
        }

        string mangleName( DeclarationWithType *decl ) {
                if ( decl->get_mangleName() != "" ) {
                        // need to incorporate scope level in order to differentiate names for destructors
                        return decl->get_scopedMangleName();
                } else {
                        return decl->get_name();
                } // if
        }

        void CodeGenerator::genAttributes( std::list< Attribute * > & attributes ) {
                if ( ! attributes.empty() ) {
                        output << "__attribute__ ((";
                        for ( Attribute *& attr : attributes ) {
                                if ( ! attr->empty() ) {
                                        output << attr->get_name() << "(";
                                        genCommaList( attr->get_parameters().begin(), attr->get_parameters().end() );
                                        output << ")";
                                }
                                output << ",";
                        }
                        output << ")) ";
                }
        }


        //*** Declarations
        void CodeGenerator::visit( FunctionDecl *functionDecl ) {
                genAttributes( functionDecl->get_attributes() );

                handleStorageClass( functionDecl );
                if ( functionDecl->get_isInline() ) {
                        output << "inline ";
                } // if
                if ( functionDecl->get_isNoreturn() ) {
                        output << "_Noreturn ";
                } // if
                output << genType( functionDecl->get_functionType(), mangleName( functionDecl ) );

                // how to get this to the Functype?
                std::list< Declaration * > olds = functionDecl->get_oldDecls();
                if ( ! olds.empty() ) {
                        output << " /* function has old declaration */";
                } // if

                // acceptAll( functionDecl->get_oldDecls(), *this );
                if ( functionDecl->get_statements() ) {
                        functionDecl->get_statements()->accept( *this );
                } // if
        }

        void CodeGenerator::visit( ObjectDecl *objectDecl ) {
                handleStorageClass( objectDecl );
                output << genType( objectDecl->get_type(), mangleName( objectDecl ) );

                if ( objectDecl->get_init() ) {
                        output << " = ";
                        objectDecl->get_init()->accept( *this );
                } // if
                if ( objectDecl->get_bitfieldWidth() ) {
                        output << ":";
                        objectDecl->get_bitfieldWidth()->accept( *this );
                } // if
        }

        void CodeGenerator::handleAggregate( AggregateDecl *aggDecl ) {
                if ( aggDecl->get_name() != "" )
                        output << aggDecl->get_name();

                std::list< Declaration * > &memb = aggDecl->get_members();

                if ( ! memb.empty() ) {
                        output << " {" << endl;

                        cur_indent += CodeGenerator::tabsize;
                        for ( std::list< Declaration* >::iterator i = memb.begin(); i != memb.end();  i++) {
                                output << indent;
                                (*i)->accept( *this );
                                output << ";" << endl;
                        }

                        cur_indent -= CodeGenerator::tabsize;

                        output << indent << "}";
                } // if
        }

        void CodeGenerator::visit( StructDecl *structDecl ) {
                output << "struct ";
                handleAggregate( structDecl );
        }

        void CodeGenerator::visit( UnionDecl *aggregateDecl ) {
                output << "union ";
                handleAggregate( aggregateDecl );
        }

        void CodeGenerator::visit( EnumDecl *aggDecl ) {
                output << "enum ";

                if ( aggDecl->get_name() != "" )
                        output << aggDecl->get_name();

                std::list< Declaration* > &memb = aggDecl->get_members();

                if ( ! memb.empty() ) {
                        output << " {" << endl;

                        cur_indent += CodeGenerator::tabsize;
                        for ( std::list< Declaration* >::iterator i = memb.begin(); i != memb.end();  i++) {
                                ObjectDecl *obj = dynamic_cast< ObjectDecl* >( *i );
                                assert( obj );
                                output << indent << mangleName( obj );
                                if ( obj->get_init() ) {
                                        output << " = ";
                                        obj->get_init()->accept( *this );
                                } // if
                                output << "," << endl;
                        } // for

                        cur_indent -= CodeGenerator::tabsize;

                        output << indent << "}";
                } // if
        }

        void CodeGenerator::visit( TraitDecl *aggregateDecl ) {}

        void CodeGenerator::visit( TypedefDecl *typeDecl ) {
                output << "typedef ";
                output << genType( typeDecl->get_base(), typeDecl->get_name() );
        }

        void CodeGenerator::visit( TypeDecl *typeDecl ) {
                // really, we should mutate this into something that isn't a TypeDecl but that requires large-scale changes,
                // still to be done
                output << "extern unsigned long " << typeDecl->get_name();
                if ( typeDecl->get_base() ) {
                        output << " = sizeof( " << genType( typeDecl->get_base(), "" ) << " )";
                } // if
        }

        void CodeGenerator::printDesignators( std::list< Expression * > & designators ) {
                typedef std::list< Expression * > DesignatorList;
                if ( designators.size() == 0 ) return;
                for ( DesignatorList::iterator iter = designators.begin(); iter != designators.end(); ++iter ) {
                        if ( dynamic_cast< NameExpr * >( *iter ) ) {
                                // if expression is a name, then initializing aggregate member
                                output << ".";
                                (*iter)->accept( *this );
                        } else {
                                // if not a simple name, it has to be a constant expression, i.e. an array designator
                                output << "[";
                                (*iter)->accept( *this );
                                output << "]";
                        }
                }
                output << " = ";
        }

        void CodeGenerator::visit( SingleInit *init ) {
                printDesignators( init->get_designators() );
                init->get_value()->accept( *this );
        }

        void CodeGenerator::visit( ListInit *init ) {
                printDesignators( init->get_designators() );
                output << "{ ";
                if ( init->begin_initializers() == init->end_initializers() ) {
                        // illegal to leave initializer list empty for scalar initializers,
                        // but always legal to have 0
                        output << "0";
                } else {
                        genCommaList( init->begin_initializers(), init->end_initializers() );
                }
                output << " }";
        }

        void CodeGenerator::visit( Constant *constant ) {
                output << constant->get_value() ;
        }

        //*** Expressions
        void CodeGenerator::visit( ApplicationExpr *applicationExpr ) {
                extension( applicationExpr );
                if ( VariableExpr *varExpr = dynamic_cast< VariableExpr* >( applicationExpr->get_function() ) ) {
                        OperatorInfo opInfo;
                        if ( varExpr->get_var()->get_linkage() == LinkageSpec::Intrinsic && operatorLookup( varExpr->get_var()->get_name(), opInfo ) ) {
                                std::list< Expression* >::iterator arg = applicationExpr->get_args().begin();
                                switch ( opInfo.type ) {
                                  case OT_PREFIXASSIGN:
                                  case OT_POSTFIXASSIGN:
                                  case OT_INFIXASSIGN:
                                  case OT_CTOR:
                                  case OT_DTOR:
                                        {
                                                assert( arg != applicationExpr->get_args().end() );
                                                if ( AddressExpr *addrExpr = dynamic_cast< AddressExpr * >( *arg ) ) {
                                                        // remove & from first assignment/ctor argument
                                                        *arg = addrExpr->get_arg();
                                                } else {
                                                        // no address-of operator, so must be a pointer - add dereference
                                                        UntypedExpr *newExpr = new UntypedExpr( new NameExpr( "*?" ) );
                                                        newExpr->get_args().push_back( *arg );
                                                        assert( (*arg)->get_results().size() == 1 );
                                                        Type * type = InitTweak::getPointerBase( (*arg)->get_results().front() );
                                                        assert( type );
                                                        newExpr->get_results().push_back( type );
                                                        *arg = newExpr;
                                                } // if
                                                break;
                                        }

                                  default:
                                        // do nothing
                                        ;
                                }

                                switch ( opInfo.type ) {
                                  case OT_INDEX:
                                        assert( applicationExpr->get_args().size() == 2 );
                                        (*arg++)->accept( *this );
                                        output << "[";
                                        (*arg)->accept( *this );
                                        output << "]";
                                        break;

                                  case OT_CALL:
                                        // there are no intrinsic definitions of the function call operator
                                        assert( false );
                                        break;

                                  case OT_CTOR:
                                  case OT_DTOR:
                                        if ( applicationExpr->get_args().size() == 1 ) {
                                                // the expression fed into a single parameter constructor or destructor
                                                // may contain side effects, so must still output this expression
                                                output << "(";
                                                (*arg++)->accept( *this );
                                                output << ") /* " << opInfo.inputName << " */";
                                        } else if ( applicationExpr->get_args().size() == 2 ) {
                                                // intrinsic two parameter constructors are essentially bitwise assignment
                                                output << "(";
                                                (*arg++)->accept( *this );
                                                output << opInfo.symbol;
                                                (*arg)->accept( *this );
                                                output << ") /* " << opInfo.inputName << " */";
                                        } else {
                                                // no constructors with 0 or more than 2 parameters
                                                assert( false );
                                        }
                                        break;

                                  case OT_PREFIX:
                                  case OT_PREFIXASSIGN:
                                        assert( applicationExpr->get_args().size() == 1 );
                                        output << "(";
                                        output << opInfo.symbol;
                                        (*arg)->accept( *this );
                                        output << ")";
                                        break;

                                  case OT_POSTFIX:
                                  case OT_POSTFIXASSIGN:
                                        assert( applicationExpr->get_args().size() == 1 );
                                        (*arg)->accept( *this );
                                        output << opInfo.symbol;
                                        break;


                                  case OT_INFIX:
                                  case OT_INFIXASSIGN:
                                        assert( applicationExpr->get_args().size() == 2 );
                                        output << "(";
                                        (*arg++)->accept( *this );
                                        output << opInfo.symbol;
                                        (*arg)->accept( *this );
                                        output << ")";
                                        break;

                                  case OT_CONSTANT:
                                  case OT_LABELADDRESS:
                                        // there are no intrinsic definitions of 0/1 or label addresses as functions
                                        assert( false );
                                }
                        } else {
                                varExpr->accept( *this );
                                output << "(";
                                genCommaList( applicationExpr->get_args().begin(), applicationExpr->get_args().end() );
                                output << ")";
                        } // if
                } else {
                        applicationExpr->get_function()->accept( *this );
                        output << "(";
                        genCommaList( applicationExpr->get_args().begin(), applicationExpr->get_args().end() );
                        output << ")";
                } // if
        }

        void CodeGenerator::visit( UntypedExpr *untypedExpr ) {
                extension( untypedExpr );
                if ( NameExpr *nameExpr = dynamic_cast< NameExpr* >( untypedExpr->get_function() ) ) {
                        OperatorInfo opInfo;
                        if ( operatorLookup( nameExpr->get_name(), opInfo ) ) {
                                std::list< Expression* >::iterator arg = untypedExpr->get_args().begin();
                                switch ( opInfo.type ) {
                                  case OT_INDEX:
                                        assert( untypedExpr->get_args().size() == 2 );
                                        (*arg++)->accept( *this );
                                        output << "[";
                                        (*arg)->accept( *this );
                                        output << "]";
                                        break;

                                  case OT_CALL:
                                        assert( false );


                                  case OT_CTOR:
                                  case OT_DTOR:
                                        if ( untypedExpr->get_args().size() == 1 ) {
                                                // the expression fed into a single parameter constructor or destructor
                                                // may contain side effects, so must still output this expression
                                                output << "(";
                                                (*arg++)->accept( *this );
                                                output << ") /* " << opInfo.inputName << " */";
                                        } else if ( untypedExpr->get_args().size() == 2 ) {
                                                // intrinsic two parameter constructors are essentially bitwise assignment
                                                output << "(";
                                                (*arg++)->accept( *this );
                                                output << opInfo.symbol;
                                                (*arg)->accept( *this );
                                                output << ") /* " << opInfo.inputName << " */";
                                        } else {
                                                // no constructors with 0 or more than 2 parameters
                                                assert( false );
                                        }
                                        break;

                                  case OT_PREFIX:
                                  case OT_PREFIXASSIGN:
                                  case OT_LABELADDRESS:
                                        assert( untypedExpr->get_args().size() == 1 );
                                        output << "(";
                                        output << opInfo.symbol;
                                        (*arg)->accept( *this );
                                        output << ")";
                                        break;

                                  case OT_POSTFIX:
                                  case OT_POSTFIXASSIGN:
                                        assert( untypedExpr->get_args().size() == 1 );
                                        (*arg)->accept( *this );
                                        output << opInfo.symbol;
                                        break;

                                  case OT_INFIX:
                                  case OT_INFIXASSIGN:
                                        assert( untypedExpr->get_args().size() == 2 );
                                        output << "(";
                                        (*arg++)->accept( *this );
                                        output << opInfo.symbol;
                                        (*arg)->accept( *this );
                                        output << ")";
                                        break;

                                  case OT_CONSTANT:
                                        // there are no intrinsic definitions of 0 or 1 as functions
                                        assert( false );
                                }
                        } else {
                                nameExpr->accept( *this );
                                output << "(";
                                genCommaList( untypedExpr->get_args().begin(), untypedExpr->get_args().end() );
                                output << ")";
                        } // if
                } else {
                        untypedExpr->get_function()->accept( *this );
                        output << "(";
                        genCommaList( untypedExpr->get_args().begin(), untypedExpr->get_args().end() );
                        output << ")";
                } // if
        }

        void CodeGenerator::visit( NameExpr *nameExpr ) {
                extension( nameExpr );
                OperatorInfo opInfo;
                if ( operatorLookup( nameExpr->get_name(), opInfo ) ) {
                        assert( opInfo.type == OT_CONSTANT );
                        output << opInfo.symbol;
                } else {
                        output << nameExpr->get_name();
                } // if
        }

        void CodeGenerator::visit( AddressExpr *addressExpr ) {
                extension( addressExpr );
                output << "(&";
                // this hack makes sure that we don't convert "constant_zero" to "0" if we're taking its address
                if ( VariableExpr *variableExpr = dynamic_cast< VariableExpr* >( addressExpr->get_arg() ) ) {
                        output << mangleName( variableExpr->get_var() );
                } else {
                        addressExpr->get_arg()->accept( *this );
                } // if
                output << ")";
        }

        void CodeGenerator::visit( CastExpr *castExpr ) {
                extension( castExpr );
                output << "(";
                if ( castExpr->get_results().empty() ) {
                        output << "(void)" ;
                } else if ( ! castExpr->get_results().front()->get_isLvalue() ) {
                        // at least one result type of cast, but not an lvalue
                        output << "(";
                        output << genType( castExpr->get_results().front(), "" );
                        output << ")";
                } else {
                        // otherwise, the cast is to an lvalue type, so the cast
                        // should be dropped, since the result of a cast is
                        // never an lvalue in C
                }
                castExpr->get_arg()->accept( *this );
                output << ")";
        }

        void CodeGenerator::visit( UntypedMemberExpr *memberExpr ) {
                assert( false );
        }

        void CodeGenerator::visit( MemberExpr *memberExpr ) {
                extension( memberExpr );
                memberExpr->get_aggregate()->accept( *this );
                output << "." << mangleName( memberExpr->get_member() );
        }

        void CodeGenerator::visit( VariableExpr *variableExpr ) {
                extension( variableExpr );
                OperatorInfo opInfo;
                if ( variableExpr->get_var()->get_linkage() == LinkageSpec::Intrinsic && operatorLookup( variableExpr->get_var()->get_name(), opInfo ) && opInfo.type == OT_CONSTANT ) {
                        output << opInfo.symbol;
                } else {
                        output << mangleName( variableExpr->get_var() );
                } // if
        }

        void CodeGenerator::visit( ConstantExpr *constantExpr ) {
                assert( constantExpr->get_constant() );
                extension( constantExpr );
                constantExpr->get_constant()->accept( *this );
        }

        void CodeGenerator::visit( SizeofExpr *sizeofExpr ) {
                extension( sizeofExpr );
                output << "sizeof(";
                if ( sizeofExpr->get_isType() ) {
                        output << genType( sizeofExpr->get_type(), "" );
                } else {
                        sizeofExpr->get_expr()->accept( *this );
                } // if
                output << ")";
        }

        void CodeGenerator::visit( AlignofExpr *alignofExpr ) {
                extension( alignofExpr );
                // use GCC extension to avoid bumping std to C11
                output << "__alignof__(";
                if ( alignofExpr->get_isType() ) {
                        output << genType( alignofExpr->get_type(), "" );
                } else {
                        alignofExpr->get_expr()->accept( *this );
                } // if
                output << ")";
        }

        void CodeGenerator::visit( UntypedOffsetofExpr *offsetofExpr ) {
                assert( false && "UntypedOffsetofExpr should not reach code generation" );
        }

        void CodeGenerator::visit( OffsetofExpr *offsetofExpr ) {
                extension( offsetofExpr );
                // use GCC builtin
                output << "__builtin_offsetof(";
                output << genType( offsetofExpr->get_type(), "" );
                output << ", " << mangleName( offsetofExpr->get_member() );
                output << ")";
        }

        void CodeGenerator::visit( OffsetPackExpr *offsetPackExpr ) {
                assert( false && "OffsetPackExpr should not reach code generation" );
        }

        void CodeGenerator::visit( LogicalExpr *logicalExpr ) {
                extension( logicalExpr );
                output << "(";
                logicalExpr->get_arg1()->accept( *this );
                if ( logicalExpr->get_isAnd() ) {
                        output << " && ";
                } else {
                        output << " || ";
                } // if
                logicalExpr->get_arg2()->accept( *this );
                output << ")";
        }

        void CodeGenerator::visit( ConditionalExpr *conditionalExpr ) {
                extension( conditionalExpr );
                output << "(";
                conditionalExpr->get_arg1()->accept( *this );
                output << " ? ";
                conditionalExpr->get_arg2()->accept( *this );
                output << " : ";
                conditionalExpr->get_arg3()->accept( *this );
                output << ")";
        }

        void CodeGenerator::visit( CommaExpr *commaExpr ) {
                extension( commaExpr );
                output << "(";
                commaExpr->get_arg1()->accept( *this );
                output << " , ";
                commaExpr->get_arg2()->accept( *this );
                output << ")";
        }

        void CodeGenerator::visit( TupleExpr *tupleExpr ) {}

        void CodeGenerator::visit( TypeExpr *typeExpr ) {}

        void CodeGenerator::visit( AsmExpr *asmExpr ) {
                extension( asmExpr );
                if ( asmExpr->get_inout() ) {
                        output << "[ ";
                        asmExpr->get_inout()->accept( *this );
                        output << " ] ";
                } // if
                asmExpr->get_constraint()->accept( *this );
                output << " ( ";
                asmExpr->get_operand()->accept( *this );
                output << " )";
        }

        //*** Statements
        void CodeGenerator::visit( CompoundStmt *compoundStmt ) {
                std::list<Statement*> ks = compoundStmt->get_kids();
                output << "{" << endl;

                cur_indent += CodeGenerator::tabsize;

                for ( std::list<Statement *>::iterator i = ks.begin(); i != ks.end();  i++ ) {
                        output << indent << printLabels( (*i)->get_labels() );
                        (*i)->accept( *this );

                        output << endl;
                        if ( wantSpacing( *i ) ) {
                                output << endl;
                        }
                }
                cur_indent -= CodeGenerator::tabsize;

                output << indent << "}";
        }

        void CodeGenerator::visit( ExprStmt *exprStmt ) {
                assert( exprStmt );
                // cast the top-level expression to void to reduce gcc warnings.
                Expression * expr = new CastExpr( exprStmt->get_expr() );
                expr->accept( *this );
                output << ";";
        }

        void CodeGenerator::visit( AsmStmt *asmStmt ) {
                output << "asm ";
                if ( asmStmt->get_voltile() ) output << "volatile ";
                if ( ! asmStmt->get_gotolabels().empty()  ) output << "goto ";
                output << "( ";
                if ( asmStmt->get_instruction() ) asmStmt->get_instruction()->accept( *this );
                output << " : ";
                genCommaList( asmStmt->get_output().begin(), asmStmt->get_output().end() );
                output << " : ";
                genCommaList( asmStmt->get_input().begin(), asmStmt->get_input().end() );
                output << " : ";
                genCommaList( asmStmt->get_clobber().begin(), asmStmt->get_clobber().end() );
                if ( ! asmStmt->get_gotolabels().empty() ) {
                        output << " : ";
                        for ( std::list<Label>::iterator begin = asmStmt->get_gotolabels().begin();; ) {
                                output << *begin++;
                                if ( begin == asmStmt->get_gotolabels().end() ) break;
                                output << ", ";
                        } // for
                } // if
                output << " );" ;
        }

        void CodeGenerator::visit( IfStmt *ifStmt ) {
                output << "if ( ";
                ifStmt->get_condition()->accept( *this );
                output << " ) ";

                ifStmt->get_thenPart()->accept( *this );

                if ( ifStmt->get_elsePart() != 0) {
                        output << " else ";
                        ifStmt->get_elsePart()->accept( *this );
                } // if
        }

        void CodeGenerator::visit( SwitchStmt *switchStmt ) {
                output << "switch ( " ;
                switchStmt->get_condition()->accept( *this );
                output << " ) ";

                output << "{" << std::endl;
                cur_indent += CodeGenerator::tabsize;

                acceptAll( switchStmt->get_branches(), *this );

                cur_indent -= CodeGenerator::tabsize;

                output << indent << "}";
        }

        void CodeGenerator::visit( CaseStmt *caseStmt ) {
                output << indent;
                if ( caseStmt->isDefault()) {
                        output << "default";
                } else {
                        output << "case ";
                        caseStmt->get_condition()->accept( *this );
                } // if
                output << ":\n";

                std::list<Statement *> sts = caseStmt->get_statements();

                cur_indent += CodeGenerator::tabsize;
                for ( std::list<Statement *>::iterator i = sts.begin(); i != sts.end();  i++) {
                        output << indent << printLabels( (*i)->get_labels() )  ;
                        (*i)->accept( *this );
                        output << endl;
                }
                cur_indent -= CodeGenerator::tabsize;
        }

        void CodeGenerator::visit( BranchStmt *branchStmt ) {
                switch ( branchStmt->get_type()) {
                  case BranchStmt::Goto:
                        if ( ! branchStmt->get_target().empty() )
                                output << "goto " << branchStmt->get_target();
                        else {
                                if ( branchStmt->get_computedTarget() != 0 ) {
                                        output << "goto *";
                                        branchStmt->get_computedTarget()->accept( *this );
                                } // if
                        } // if
                        break;
                  case BranchStmt::Break:
                        output << "break";
                        break;
                  case BranchStmt::Continue:
                        output << "continue";
                        break;
                }
                output << ";";
        }


        void CodeGenerator::visit( ReturnStmt *returnStmt ) {
                output << "return ";

                // xxx -- check for null expression;
                if ( returnStmt->get_expr() ) {
                        returnStmt->get_expr()->accept( *this );
                } // if
                output << ";";
        }

        void CodeGenerator::visit( WhileStmt *whileStmt ) {
                if ( whileStmt->get_isDoWhile() ) {
                        output << "do" ;
                } else {
                        output << "while (" ;
                        whileStmt->get_condition()->accept( *this );
                        output << ")";
                } // if
                output << " ";

                output << CodeGenerator::printLabels( whileStmt->get_body()->get_labels() );
                whileStmt->get_body()->accept( *this );

                output << indent;

                if ( whileStmt->get_isDoWhile() ) {
                        output << " while (" ;
                        whileStmt->get_condition()->accept( *this );
                        output << ");";
                } // if
        }

        void CodeGenerator::visit( ForStmt *forStmt ) {
                // initialization is always hoisted, so don't
                // bother doing anything with that
                output << "for (;";

                if ( forStmt->get_condition() != 0 ) {
                        forStmt->get_condition()->accept( *this );
                }
                output << ";";

                if ( forStmt->get_increment() != 0 ) {
                        // cast the top-level expression to void to reduce gcc warnings.
                        Expression * expr = new CastExpr( forStmt->get_increment() );
                        expr->accept( *this );
                }
                output << ") ";

                if ( forStmt->get_body() != 0 ) {
                        output << CodeGenerator::printLabels( forStmt->get_body()->get_labels() );
                        forStmt->get_body()->accept( *this );
                } // if
        }

        void CodeGenerator::visit( NullStmt *nullStmt ) {
                //output << indent << CodeGenerator::printLabels( nullStmt->get_labels() );
                output << "/* null statement */ ;";
        }

        void CodeGenerator::visit( DeclStmt *declStmt ) {
                declStmt->get_decl()->accept( *this );

                if ( doSemicolon( declStmt->get_decl() ) ) {
                        output << ";";
                } // if
        }

        std::string CodeGenerator::printLabels( std::list< Label > &l ) {
                std::string str( "" );
                l.unique(); // assumes a sorted list. Why not use set?

                for ( std::list< Label >::iterator i = l.begin(); i != l.end(); i++ )
                        str += *i + ": ";

                return str;
        }

        void CodeGenerator::handleStorageClass( Declaration *decl ) {
                switch ( decl->get_storageClass() ) {
                  case DeclarationNode::Extern:
                        output << "extern ";
                        break;
                  case DeclarationNode::Static:
                        output << "static ";
                        break;
                  case DeclarationNode::Auto:
                        // silently drop storage class
                        break;
                  case DeclarationNode::Register:
                        output << "register ";
                        break;
                  case DeclarationNode::Inline:
                        output << "inline ";
                        break;
                  case DeclarationNode::Fortran:
                        output << "fortran ";
                        break;
                  case DeclarationNode::Noreturn:
                        output << "_Noreturn ";
                        break;
                  case DeclarationNode::Threadlocal:
                        output << "_Thread_local ";
                        break;
                  case DeclarationNode::NoStorageClass:
                        break;
                } // switch
        }
} // namespace CodeGen

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