source: src/ResolvExpr/CastCost.cc @ 6fb1921

//
// 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.
//
// CastCost.cc --
//
// Author           : Richard C. Bilson
// Created On       : Sun May 17 06:57:43 2015
// Last Modified By : Peter A. Buhr
// Last Modified On : Tue Feb  2 15:34:36 2016
// Update Count     : 7
//

#include <cassert>                       // for assert

#include "ConversionCost.h"              // for ConversionCost
#include "Cost.h"                        // for Cost, Cost::infinity
#include "ResolvExpr/TypeEnvironment.h"  // for TypeEnvironment, EqvClass
#include "SymTab/Indexer.h"              // for Indexer
#include "SynTree/Declaration.h"         // for TypeDecl, NamedTypeDecl
#include "SynTree/Type.h"                // for PointerType, Type, TypeInstType
#include "typeops.h"                     // for typesCompatibleIgnoreQualifiers

#if 0
#define PRINT(x) x
#else
#define PRINT(x)
#endif

namespace ResolvExpr {
        struct CastCost : public ConversionCost {
          public:
                CastCost( Type *dest, const SymTab::Indexer &indexer, const TypeEnvironment &env, CostFunction costFunc );

                using ConversionCost::previsit;
                using ConversionCost::postvisit;
                void postvisit( BasicType * basicType );
                void postvisit( PointerType * pointerType );
        };

        Cost castCost( Type *src, Type *dest, const SymTab::Indexer &indexer, const TypeEnvironment &env ) {
                if ( TypeInstType *destAsTypeInst = dynamic_cast< TypeInstType* >( dest ) ) {
                        if ( const EqvClass* eqvClass = env.lookup( destAsTypeInst->get_name() ) ) {
                                if ( eqvClass->type ) {
                                        return castCost( src, eqvClass->type, indexer, env );
                                } else {
                                        return Cost::infinity;
                                }
                        } else if ( NamedTypeDecl *namedType = indexer.lookupType( destAsTypeInst->get_name() ) ) {
                                // all typedefs should be gone by this point
                                TypeDecl *type = strict_dynamic_cast< TypeDecl* >( namedType );
                                if ( type->base ) {
                                        return castCost( src, type->base, indexer, env ) + Cost::safe;
                                } // if
                        } // if
                } // if

                PRINT(
                        std::cerr << "castCost ::: src is ";
                        src->print( std::cerr );
                        std::cerr << std::endl << "dest is ";
                        dest->print( std::cerr );
                        std::cerr << std::endl << "env is" << std::endl;
                        env.print( std::cerr, 8 );
                )

                if ( typesCompatibleIgnoreQualifiers( src, dest, indexer, env ) ) {
                        PRINT( std::cerr << "compatible!" << std::endl; )
                        return Cost::zero;
                } else if ( dynamic_cast< VoidType* >( dest ) ) {
                        return Cost::safe;
                } else if ( ReferenceType * refType = dynamic_cast< ReferenceType * > ( dest ) ) {
                        PRINT( std::cerr << "conversionCost: dest is reference" << std::endl; )
                        return convertToReferenceCost( src, refType, indexer, env, [](Type * t1, Type * t2, const SymTab::Indexer & indexer, const TypeEnvironment & env ) {
                                return ptrsCastable( t1, t2, env, indexer );
                        });
                } else {
                        PassVisitor<CastCost> converter( dest, indexer, env, castCost );
                        src->accept( converter );
                        if ( converter.pass.get_cost() == Cost::infinity ) {
                                return Cost::infinity;
                        } else {
                                // xxx - why are we adding cost 0 here?
                                return converter.pass.get_cost() + Cost::zero;
                        } // if
                } // if
        }

        CastCost::CastCost( Type *dest, const SymTab::Indexer &indexer, const TypeEnvironment &env, CostFunction costFunc )
                : ConversionCost( dest, indexer, env, costFunc ) {
        }

        void CastCost::postvisit( BasicType *basicType ) {
                PointerType *destAsPointer = dynamic_cast< PointerType* >( dest );
                if ( destAsPointer && basicType->isInteger() ) {
                        // necessary for, e.g. unsigned long => void*
                        cost = Cost::unsafe;
                } else {
                        cost = conversionCost( basicType, dest, indexer, env );
                } // if
        }

        void CastCost::postvisit( PointerType *pointerType ) {
                if ( PointerType *destAsPtr = dynamic_cast< PointerType* >( dest ) ) {
                        if ( pointerType->get_qualifiers() <= destAsPtr->get_qualifiers() && typesCompatibleIgnoreQualifiers( pointerType->base, destAsPtr->base, indexer, env ) ) {
                                cost = Cost::safe;
                        } else {
                                TypeEnvironment newEnv( env );
                                newEnv.add( pointerType->forall );
                                newEnv.add( pointerType->base->forall );
                                int castResult = ptrsCastable( pointerType->base, destAsPtr->base, newEnv, indexer );
                                if ( castResult > 0 ) {
                                        cost = Cost::safe;
                                } else if ( castResult < 0 ) {
                                        cost = Cost::infinity;
                                } // if
                        } // if
                } else if ( BasicType *destAsBasic = dynamic_cast< BasicType* >( dest ) ) {
                        if ( destAsBasic->isInteger() ) {
                                // necessary for, e.g. void* => unsigned long
                                cost = Cost::unsafe;
                        } // if
                }
        }
} // namespace ResolvExpr

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