source: src/ResolvExpr/CastCost.cc @ 6c2dc00

//
// 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 : Andrew Beach
// Last Modified On : Tue Oct  4 15:00:00 2019
// Update Count     : 9
//

#include <cassert>                       // for assert

#include "AST/Print.hpp"
#include "AST/SymbolTable.hpp"
#include "AST/Type.hpp"
#include "AST/TypeEnvironment.hpp"
#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_old : public ConversionCost {
          public:
                CastCost_old( const Type * dest, bool srcIsLvalue,
                        const SymTab::Indexer &indexer, const TypeEnvironment &env, CostFunction costFunc );

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

        Cost castCost( const Type * src, const Type * dest, bool srcIsLvalue,
                        const SymTab::Indexer &indexer, const TypeEnvironment &env ) {
                if ( const TypeInstType * destAsTypeInst = dynamic_cast< const TypeInstType * >( dest ) ) {
                        if ( const EqvClass * eqvClass = env.lookup( destAsTypeInst->name ) ) {
                                if ( eqvClass->type ) {
                                        return castCost( src, eqvClass->type, srcIsLvalue, indexer, env );
                                } else {
                                        return Cost::infinity;
                                }
                        } else if ( const NamedTypeDecl * namedType = indexer.lookupType( destAsTypeInst->name ) ) {
                                // all typedefs should be gone by this point
                                const TypeDecl * type = strict_dynamic_cast< const TypeDecl * >( namedType );
                                if ( type->base ) {
                                        return castCost( src, type->base, srcIsLvalue, 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< const VoidType * >( dest ) ) {
                        return Cost::safe;
                } else if ( const ReferenceType * refType = dynamic_cast< const ReferenceType * > ( dest ) ) {
                        PRINT( std::cerr << "conversionCost: dest is reference" << std::endl; )
                        return convertToReferenceCost( src, refType, srcIsLvalue, indexer, env, [](const Type * t1, const Type * t2, const SymTab::Indexer & indexer, const TypeEnvironment & env ) {
                                return ptrsCastable( t1, t2, env, indexer );
                        });
                } else {
                        PassVisitor<CastCost_old> converter(
                                dest, srcIsLvalue, indexer, env,
                                (Cost (*)( const Type *, const Type *, bool, const SymTab::Indexer &, const TypeEnvironment & ))
                                        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_old::CastCost_old( const Type * dest, bool srcIsLvalue,
                        const SymTab::Indexer &indexer, const TypeEnvironment &env, CostFunction costFunc )
                : ConversionCost( dest, srcIsLvalue, indexer, env, costFunc ) {
        }

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

        void CastCost_old::postvisit( const PointerType * pointerType ) {
                if ( const PointerType * destAsPtr = dynamic_cast< const PointerType * >( dest ) ) {
                        if ( pointerType->tq <= destAsPtr->tq && 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 ( const BasicType * destAsBasic = dynamic_cast< const BasicType * >( dest ) ) {
                        if ( destAsBasic->isInteger() ) {
                                // necessary for, e.g. void * => unsigned long
                                cost = Cost::unsafe;
                        } // if
                }
        }

namespace {
        struct CastCost_new : public ConversionCost_new {
                using ConversionCost_new::previsit;
                using ConversionCost_new::postvisit;

                CastCost_new(
                        const ast::Type * dst, bool srcIsLvalue, const ast::SymbolTable & symtab,
                        const ast::TypeEnvironment & env, CostCalculation costFunc )
                : ConversionCost_new( dst, srcIsLvalue, symtab, env, costFunc ) {}

                void postvisit( const ast::BasicType * basicType ) {
                        auto ptr = dynamic_cast< const ast::PointerType * >( dst );
                        if ( ptr && basicType->isInteger() ) {
                                // needed for, e.g. unsigned long => void *
                                cost = Cost::unsafe;
                        } else {
                                cost = conversionCost( basicType, dst, srcIsLvalue, symtab, env );
                        }
                }

                void postvisit( const ast::PointerType * pointerType ) {
                        if ( auto ptr = dynamic_cast< const ast::PointerType * >( dst ) ) {
                                if (
                                        pointerType->qualifiers <= ptr->qualifiers
                                        && typesCompatibleIgnoreQualifiers( pointerType->base, ptr->base, symtab, env )
                                ) {
                                        cost = Cost::safe;
                                } else {
                                        ast::TypeEnvironment newEnv{ env };
                                        if ( auto wParams = pointerType->base.as< ast::FunctionType >() ) {
                                                newEnv.add( wParams->forall );
                                        }
                                        int castResult = ptrsCastable( pointerType->base, ptr->base, symtab, newEnv );
                                        if ( castResult > 0 ) {
                                                cost = Cost::safe;
                                        } else if ( castResult < 0 ) {
                                                cost = Cost::infinity;
                                        }
                                }
                        } else if ( auto basic = dynamic_cast< const ast::BasicType * >( dst ) ) {
                                if ( basic->isInteger() ) {
                                        // necessary for, e.g. void * => unsigned long
                                        cost = Cost::unsafe;
                                }
                        }
                }
        };

        #warning For overload resolution between the two versions.
        int localPtrsCastable(const ast::Type * t1, const ast::Type * t2,
                        const ast::SymbolTable & symtab, const ast::TypeEnvironment & env ) {
                return ptrsCastable( t1, t2, symtab, env );
        }
        Cost localCastCost(
                const ast::Type * src, const ast::Type * dst, bool srcIsLvalue,
                const ast::SymbolTable & symtab, const ast::TypeEnvironment & env
        ) { return castCost( src, dst, srcIsLvalue, symtab, env ); }
} // anonymous namespace



Cost castCost(
        const ast::Type * src, const ast::Type * dst, bool srcIsLvalue,
        const ast::SymbolTable & symtab, const ast::TypeEnvironment & env
) {
        if ( auto typeInst = dynamic_cast< const ast::TypeInstType * >( dst ) ) {
                if ( const ast::EqvClass * eqvClass = env.lookup( *typeInst ) ) {
                        // check cast cost against bound type, if present
                        if ( eqvClass->bound ) {
                                return castCost( src, eqvClass->bound, srcIsLvalue, symtab, env );
                        } else {
                                return Cost::infinity;
                        }
                } else if ( const ast::NamedTypeDecl * named = symtab.lookupType( typeInst->name ) ) {
                        // all typedefs should be gone by now
                        auto type = strict_dynamic_cast< const ast::TypeDecl * >( named );
                        if ( type->base ) {
                                return castCost( src, type->base, srcIsLvalue, symtab, env ) + Cost::safe;
                        }
                }
        }

        PRINT(
                std::cerr << "castCost ::: src is ";
                ast::print( std::cerr, src );
                std::cerr << std::endl << "dest is ";
                ast::print( std::cerr, dst );
                std::cerr << std::endl << "env is" << std::endl;
                ast::print( std::cerr, env, 2 );
        )

        if ( typesCompatibleIgnoreQualifiers( src, dst, symtab, env ) ) {
                PRINT( std::cerr << "compatible!" << std::endl; )
                return Cost::zero;
        } else if ( dynamic_cast< const ast::VoidType * >( dst ) ) {
                return Cost::safe;
        } else if ( auto refType = dynamic_cast< const ast::ReferenceType * >( dst ) ) {
                PRINT( std::cerr << "conversionCost: dest is reference" << std::endl; )
                #warning cast on ptrsCastable artifact of having two functions, remove when port done
                return convertToReferenceCost(
                        src, refType, srcIsLvalue, symtab, env, localPtrsCastable );
        } else {
                #warning cast on castCost artifact of having two functions, remove when port done
                ast::Pass< CastCost_new > converter(
                        dst, srcIsLvalue, symtab, env, localCastCost );
                src->accept( converter );
                return converter.core.cost;
        }
}

} // namespace ResolvExpr

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