source: src/ControlStruct/LabelFixer.cc @ be5aa1b

//
// 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.
//
// LabelFixer.cc -- 
//
// Author           : Rodolfo G. Esteves
// Created On       : Mon May 18 07:44:20 2015
// Last Modified By : Rob Schluntz
// Last Modified On : Wed May 27 16:16:14 2015
// Update Count     : 4
//

#include <list>
#include <cassert>

#include "LabelFixer.h"
#include "MLEMutator.h"
#include "SynTree/Statement.h"
#include "SynTree/Declaration.h"
#include "utility.h"

namespace ControlStruct {
        LabelFixer::Entry::Entry( Statement *to, Statement *from ) : definition ( to ) {
                if ( from != 0 )
                        usage.push_back( from );
        }

        bool LabelFixer::Entry::insideLoop() {
                return ( dynamic_cast< ForStmt * > ( definition ) ||
                                 dynamic_cast< WhileStmt * > ( definition )  );
        }

        LabelFixer::LabelFixer( LabelGenerator *gen ) : generator ( gen ) {
                if ( generator == 0 )
                        generator = LabelGenerator::getGenerator();
        }

        void LabelFixer::visit( FunctionDecl *functionDecl ) {
                maybeAccept( functionDecl->get_statements(), *this );

                MLEMutator mlemut( resolveJumps(), generator );
                functionDecl->acceptMutator( mlemut );
        }

        void LabelFixer::visit( Statement *stmt ) {
                std::list< Label > &labels = stmt->get_labels();

                if ( ! labels.empty() ) {
                        Label current = setLabelsDef( labels, stmt );
                        labels.clear();
                        labels.push_front( current );
                } // if
        }

        void LabelFixer::visit( BranchStmt *branchStmt ) {
                visit ( ( Statement * )branchStmt );  // the labels this statement might have

                Label target;
                if ( (target = branchStmt->get_target()) != "" ) {
                        setLabelsUsg( target, branchStmt );
                } //else       /* computed goto or normal exit-loop statements */
        }

        Label LabelFixer::setLabelsDef( std::list< Label > &llabel, Statement *definition ) {
                assert( definition != 0 );
                Entry *entry = new Entry( definition );
                bool used = false;

                for ( std::list< Label >::iterator i = llabel.begin(); i != llabel.end(); i++ )
                        if ( labelTable.find( *i ) == labelTable.end() )
                                { used = true; labelTable[ *i ] = entry; } // undefined and unused
                        else
                                if ( labelTable[ *i ]->defined() )
                                        throw SemanticError( "Duplicate definition of label: " + *i );
                                else
                                        labelTable[ *i ]->set_definition( definition );

                if ( ! used ) delete entry;

                return labelTable[ llabel.front() ]->get_label();  // this *must* exist
        }

        Label LabelFixer::setLabelsUsg( Label orgValue, Statement *use ) {
                assert( use != 0 );

                if ( labelTable.find( orgValue ) != labelTable.end() )
                        labelTable[ orgValue ]->add_use( use );         // the label has been defined or used before
                else
                        labelTable[ orgValue ] = new Entry( 0, use );

                return labelTable[ orgValue ]->get_label();
        }

        std::map<Label, Statement * > *LabelFixer::resolveJumps() throw ( SemanticError ) {
                std::map< Statement *, Entry * > def_us;

                for ( std::map< Label, Entry *>::iterator i = labelTable.begin(); i != labelTable.end(); i++ ) {
                        Entry *e = i->second;

                        if ( def_us.find ( e->get_definition() ) == def_us.end() ) {
                                def_us[ e->get_definition() ] = e;                              
                        } else {
                                if ( e->used() )
                                        def_us[ e->get_definition() ]->add_uses( e->get_uses() );
                        }
                }

                // get rid of labelTable
                for ( std::map< Statement *, Entry * >::iterator i = def_us.begin(); i != def_us.end(); i++ ) {
                        Statement *to = (*i).first;
                        std::list< Statement *> &from = (*i).second->get_uses();
                        Label finalLabel = generator->newLabel();
                        (*i).second->set_label( finalLabel );

                        if ( to == 0 ) {
                                BranchStmt *first_use = dynamic_cast<BranchStmt *>(from.back());
                                Label undef("");
                                if ( first_use != 0 )
                                        undef = first_use->get_target();
                                throw SemanticError ( "'" + undef + "' label not defined");
                        }

                        to->get_labels().clear();
                        to->get_labels().push_back( finalLabel );

                        for ( std::list< Statement *>::iterator j = from.begin(); j != from.end(); j++ ) {
                                BranchStmt *jumpTo = dynamic_cast< BranchStmt * > ( *j );
                                assert( jumpTo != 0 );
                                jumpTo->set_target( finalLabel );
                        } // for
                } // for

                // reverse table
                std::map< Label, Statement * > *ret = new std::map< Label, Statement * >();
                for ( std::map< Statement *, Entry * >::iterator i = def_us.begin(); i != def_us.end(); i++ ) 
                        (*ret)[ (*i).second->get_label() ] = (*i).first;

                return ret;
        }
}  // namespace ControlStruct

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