source: src/ControlStruct/LabelFixer.cc @ 640b3df

//
// 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 : Peter A. Buhr
// Last Modified On : Tue Feb  1 09:12:09 2022
// Update Count     : 162
//

#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< WhileDoStmt * > ( 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() {
        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: //