source: src/ControlStruct/LabelFixer.cc @ 5b7a3662

//
// 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 : Andrew Beach
// Last Modified On : Tue Jan 21 10:32:00 2020
// Update Count     : 160
//

#include <cassert>                         // for assert
#include <list>                            // for list, _List_iterator, list...
#include <string>                          // for operator+, string, operator==
#include <utility>                         // for pair

#include "ControlStruct/LabelGenerator.h"  // for LabelGenerator
#include "LabelFixer.h"
#include "MLEMutator.h"                    // for MultiLevelExitMutator
#include "SynTree/Declaration.h"           // for FunctionDecl
#include "SynTree/Expression.h"            // for NameExpr, Expression, Unty...
#include "SynTree/Statement.h"             // for Statement, BranchStmt, Com...

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::previsit( FunctionDecl * ) {
                // need to go into a nested function in a fresh state
                GuardValue( labelTable );
                labelTable.clear();
        }

        void LabelFixer::postvisit( FunctionDecl * functionDecl ) {
                PassVisitor<MultiLevelExitMutator> mlem( resolveJumps(), generator );
                // We start in the body so we can stop when we hit another FunctionDecl.
                maybeMutate( functionDecl->statements, mlem );
        }

        // prune to at most one label definition for each statement
        void LabelFixer::previsit( 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::previsit( BranchStmt * branchStmt ) {
                previsit( ( Statement *)branchStmt );

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

        void LabelFixer::previsit( LabelAddressExpr * addrExpr ) {
                Label & target = addrExpr->arg;
                assert( target != "" );
                setLabelsUsg( target, addrExpr );
        }


        // 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 );

                for ( std::list< Label >::iterator i = llabel.begin(); i != llabel.end(); i++ ) {
                        Label & l = *i;
                        l.set_statement( definition ); // attach statement to the label to be used later
                        if ( labelTable.find( l ) == 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[ l ] = new Entry( definition );
                        } else if ( labelTable[ l ]->defined() ) {
                                // defined twice, error
                                SemanticError( l.get_statement()->location,
                                        "Duplicate definition of label: " + l.get_name() );
                        } else {
                                // used previously, but undefined until now -> link with this entry
                                // Question: Is changing objects important?
                                delete labelTable[ l ];
                                labelTable[ l ] = new Entry( definition );
                        } // 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 to 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 ( SemanticErrorException ) {
                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() ) {
                                SemanticError( i->first.get_statement()->location, "Use of undefined label: " + i->first.get_name() );
                        }
                        (*ret)[ i->first ] = i->second->get_definition();
                }

                return ret;
        }
}  // namespace ControlStruct

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