source: src/ControlStruct/LabelFixer.cc @ b70b6fc

//
// 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 : Tue Jul 28 13:32:43 2015
// Update Count     : 156
//

#include <list>
#include <cassert>

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

#include <iostream>

namespace ControlStruct {
        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 ) {
                // need to go into a nested function in a fresh state
                std::map < Label, Entry *> oldLabelTable = labelTable;
                labelTable.clear();

                maybeAccept( functionDecl->get_statements(), *this );

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

                // and remember the outer function's labels when
                // returning to it
                labelTable = oldLabelTable;
        }

        // prune to at most one label definition for each statement
        void LabelFixer::visit( Statement *stmt ) {
                std::list< Label > &labels = stmt->get_labels();

                if ( ! labels.empty() ) {
                        // only remember one label for each statement
                        Label current = setLabelsDef( labels, stmt );
                } // if
        }

        void LabelFixer::visit( BranchStmt *branchStmt ) {
                visit ( ( Statement * )branchStmt );

                // for labeled branches, add an entry to the label table
                Label target = branchStmt->get_target();
                if ( target != "" ) {
                        setLabelsUsg( target, branchStmt );
                }
        }

        void LabelFixer::visit( UntypedExpr *untyped ) {
                if ( NameExpr * func = dynamic_cast< NameExpr * >( untyped->get_function() ) ) {
                        if ( func->get_name() == "&&" ) {
                                NameExpr * arg = dynamic_cast< NameExpr * >( untyped->get_args().front() );
                                Label target = arg->get_name();
                                assert( target != "" );
                                setLabelsUsg( target, untyped );
                        } else {
                                Visitor::visit( untyped );
                        }
                }
        }


        // sets the definition of the labelTable entry to be the provided 
        // statement for every label in the list parameter. Happens for every kind of statement
        Label LabelFixer::setLabelsDef( std::list< Label > &llabel, Statement *definition ) {
                assert( definition != 0 );
                assert( llabel.size() > 0 );

                Entry * e = new Entry( definition );

                for ( std::list< Label >::iterator i = llabel.begin(); i != llabel.end(); i++ ) {
                        if ( labelTable.find( *i ) == labelTable.end() ) {
                                // all labels on this statement need to use the same entry, so this should only be created once
                                // undefined and unused until now, add an entry
                                labelTable[ *i ] =  e;
                        } else if ( labelTable[ *i ]->defined() ) {
                                // defined twice, error
                                throw SemanticError( "Duplicate definition of label: " + *i );
                        }       else {
                                // used previously, but undefined until now -> link with this entry
                                delete labelTable[ *i ];
                                labelTable[ *i ] = e;
                        } // if
                } // for

                // produce one of the labels attached to this statement to be 
                // temporarily used as the canonical label
                return labelTable[ llabel.front() ]->get_label();
        }

        // A label was used, add it ot the table if it isn't already there
        template< typename UsageNode >
        void LabelFixer::setLabelsUsg( Label orgValue, UsageNode *use ) {
                assert( use != 0 );

                // add label with an unknown origin
                if ( labelTable.find( orgValue ) == labelTable.end() ) {
                        labelTable[ orgValue ] = new Entry( 0 );
                }
        }

        // Builds a table that maps a label to its defining statement.
        std::map<Label, Statement * > *LabelFixer::resolveJumps() throw ( SemanticError ) {
                std::map< Label, Statement * > *ret = new std::map< Label, Statement * >();
                for ( std::map< Label, Entry * >::iterator i = labelTable.begin(); i != labelTable.end(); ++i ) {
                        if ( ! i->second->defined() ) {
                                throw SemanticError( "Use of undefined label: " + i->first );
                        }
                        (*ret)[ i->first ] = i->second->get_definition();
                }

                return ret;
        }
}  // namespace ControlStruct

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