source: src/ControlStruct/MLEMutator.cc @ d939274

//
// 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.
//
// MLEMutator.cc -- 
//
// Author           : Rodolfo G. Esteves
// Created On       : Mon May 18 07:44:20 2015
// Last Modified By : Rob Schluntz
// Last Modified On : Tue Jun 02 13:43:01 2015
// Update Count     : 92
//

#include <cassert>
#include <algorithm>

#include "MLEMutator.h"
#include "SynTree/Statement.h"

namespace ControlStruct {
        MLEMutator::~MLEMutator() {
                delete targetTable;
                targetTable = 0;
        }

        CompoundStmt* MLEMutator::mutate( CompoundStmt *cmpndStmt ) {
                bool labeledBlock = false;
                if ( !(cmpndStmt->get_labels().empty()) ) {
                        labeledBlock = true;
                        enclosingBlocks.push_back( Entry( cmpndStmt ) );
                } // if

                // a child statement may set the break label
                // - if they do, attach it to the next statement
                std::list< Statement * > &kids = cmpndStmt->get_kids();
                for ( std::list< Statement * >::iterator k = kids.begin(); k != kids.end(); k++ ) {
                        *k = (*k)->acceptMutator(*this);

                        if ( ! get_breakLabel().empty() ) {
                                std::list< Statement * >::iterator next = k+1;
                                if ( next == kids.end() ) {
                                        std::list<Label> ls; ls.push_back( get_breakLabel() );
                                        kids.push_back( new NullStmt( ls ) );
                                } else {
                                        (*next)->get_labels().push_back( get_breakLabel() );
                                }

                                set_breakLabel("");
                        } // if
                } // for

                if ( labeledBlock ) {
                        assert( ! enclosingBlocks.empty() );
                        if ( ! enclosingBlocks.back().get_breakExit().empty() ) {
                                set_breakLabel( enclosingBlocks.back().get_breakExit() );
                        }
                        enclosingBlocks.pop_back();
                } // if

                return cmpndStmt;
        }

        Statement *MLEMutator::mutate( WhileStmt *whileStmt ) {
                enclosingLoops.push_back( Entry( whileStmt ) );
                whileStmt->set_body ( whileStmt->get_body()->acceptMutator( *this ) );

                Entry &e = enclosingLoops.back();
                assert ( e == whileStmt );
                whileStmt->set_body( mutateLoop( whileStmt->get_body(), e ) );
                enclosingLoops.pop_back();

                return whileStmt;
        }

        Statement *MLEMutator::mutate( ForStmt *forStmt ) {
                enclosingLoops.push_back( Entry( forStmt ) );
                forStmt->set_body( maybeMutate( forStmt->get_body(), *this ) );

                Entry &e = enclosingLoops.back();
                assert ( e == forStmt );
                forStmt->set_body( mutateLoop( forStmt->get_body(), e ) );
                enclosingLoops.pop_back();

                return forStmt;
        }

        Statement *MLEMutator::mutate( BranchStmt *branchStmt ) throw ( SemanticError ) {
                std::string originalTarget = branchStmt->get_originalTarget();

                if ( branchStmt->get_type() == BranchStmt::Goto )
                        return branchStmt;

                // test if continue target is a loop
                if ( branchStmt->get_type() == BranchStmt::Continue) {
                        if ( enclosingLoops.empty() ) {
                                throw SemanticError( "'continue' outside a loop" );
                        } else if ( std::find( enclosingLoops.begin(), enclosingLoops.end(), (*targetTable)[branchStmt->get_target()] ) == enclosingLoops.end() ) {
                                throw SemanticError( "'continue' target label must be an enclosing loop: " + originalTarget );
                        }
                }

                if ( branchStmt->get_type() == BranchStmt::Break && (enclosingLoops.empty() && enclosingSwitches.empty() && enclosingBlocks.empty() ) )
                        throw SemanticError( "'break' outside a loop or switch" );

                if ( branchStmt->get_target() == "" ) return branchStmt;

                if ( targetTable->find( branchStmt->get_target() ) == targetTable->end() )
                        throw SemanticError("The label defined in the exit loop statement does not exist: " + originalTarget );  // shouldn't happen (since that's already checked)

                std::list< Entry >::iterator check;
                if ( ( check = std::find( enclosingLoops.begin(), enclosingLoops.end(), (*targetTable)[branchStmt->get_target()] ) ) == enclosingLoops.end() )
                        // not in loop, checking if in block
                        if ( (check = std::find( enclosingBlocks.begin(), enclosingBlocks.end(), (*targetTable)[branchStmt->get_target()] )) == enclosingBlocks.end() )
                                // neither in loop nor in block, checking if in switch/choose
                                if ( (check = std::find( enclosingSwitches.begin(), enclosingSwitches.end(), (*targetTable)[branchStmt->get_target()] )) == enclosingSwitches.end() )
                                        throw SemanticError("The target specified in the exit loop statement does not correspond to an enclosing control structure: " + originalTarget );

                if ( enclosingLoops.back() == (*check) )
                        return branchStmt;                              // exit the innermost loop (labels unnecessary)

                Label newLabel;
                switch ( branchStmt->get_type() ) {
                  case BranchStmt::Break:
                                if ( check->get_breakExit() != "" ) {
                                        newLabel = check->get_breakExit();
                                } else {
                                        newLabel = generator->newLabel();
                                        check->set_breakExit( newLabel );
                                } // if
                                break;
                  case BranchStmt::Continue:
                                if ( check->get_contExit() != "" ) {
                                        newLabel = check->get_contExit();
                                } else {
                                        newLabel = generator->newLabel();
                                        check->set_contExit( newLabel );
                                } // if
                                break;
                  default:
                                return 0;                                       // shouldn't be here
                } // switch

                return new BranchStmt( std::list<Label>(), newLabel, BranchStmt::Goto );
        }

        template< typename SwitchClass >
        Statement *handleSwitchStmt( SwitchClass *switchStmt, MLEMutator &mutator ) {
                // set up some aliases so that the rest of the code isn't messy
                typedef MLEMutator::Entry Entry;
                LabelGenerator *generator = mutator.generator;
                std::list< Entry > &enclosingSwitches = mutator.enclosingSwitches;

                Label brkLabel = generator->newLabel();
                enclosingSwitches.push_back( Entry(switchStmt, "", brkLabel) );
                mutateAll( switchStmt->get_branches(), mutator ); 
                {
                        // check if this is necessary (if there is a break to this point, otherwise do not generate

                        // for the purposes of keeping switch statements uniform (i.e. all statements that are 
                        // direct children of a switch should be CastStmts), append the exit label + break to the 
                        // last case statement; create a default case if there are no cases
                        std::list< Statement * > &branches = switchStmt->get_branches();
                        if ( branches.empty() ) {
                                branches.push_back( CaseStmt::makeDefault() );
                        }

                        if ( CaseStmt * c = dynamic_cast< CaseStmt * >( branches.back() ) ) {
                                std::list<Label> temp; temp.push_back( brkLabel );
                                c->get_statements().push_back( new BranchStmt( temp, Label(""), BranchStmt::Break ) );
                        } else assert(0);
                }
                assert ( enclosingSwitches.back() == switchStmt );
                enclosingSwitches.pop_back();
                return switchStmt;
        }

        Statement *MLEMutator::mutate( SwitchStmt *switchStmt ) {
                return handleSwitchStmt( switchStmt, *this );
        }

        Statement *MLEMutator::mutate( ChooseStmt *switchStmt ) {
                return handleSwitchStmt( switchStmt, *this );           
        }

        Statement *MLEMutator::mutateLoop( Statement *bodyLoop, Entry &e ) {
                // ensure loop body is a block
                CompoundStmt *newBody;
                if ( ! (newBody = dynamic_cast<CompoundStmt *>( bodyLoop )) ) {
                        newBody = new CompoundStmt( std::list< Label >() );
                        newBody->get_kids().push_back( bodyLoop );
                } // if

                Label endLabel = e.get_contExit();

                if ( e.get_breakExit() != "" ) {
                        if ( endLabel == "" ) endLabel = generator->newLabel();
                        // check for whether this label is used or not, so as to not generate extraneous gotos
                        if (e.breakExitUsed)
                                newBody->get_kids().push_back( new BranchStmt( std::list< Label >(), endLabel, BranchStmt::Goto ) );
                        // xxx
                        //std::list< Label > ls; ls.push_back( e.get_breakExit() );
                        set_breakLabel( e.get_breakExit() );
                        //newBody->get_kids().push_back( new BranchStmt( ls, "", BranchStmt::Break ) );
                } // if

                if ( e.get_breakExit() != "" || e.get_contExit() != "" ) {
                        if (dynamic_cast< NullStmt *>( newBody->get_kids().back() ))
                                newBody->get_kids().back()->get_labels().push_back( endLabel );
                        else {
                                std::list < Label > ls; ls.push_back( endLabel );
                                newBody->get_kids().push_back( new NullStmt( ls ) );
                        } // if
                } // if

                return newBody;
        }

        //*** Entry's methods - ensure these labels can be set at most once
        void MLEMutator::Entry::set_contExit( Label l ) {
                assert ( contExit == "" || contExit == l );
                contExit = l;
        }

        void MLEMutator::Entry::set_breakExit( Label l ) {
                assert ( breakExit == "" || breakExit == l );
                breakExit = l;
        }
} // namespace ControlStruct

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