source: src/GenPoly/InstantiateGeneric.cc@ df47e2f

//
// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// InstantiateGeneric.cc --
//
// Author           : Aaron B. Moss
// Created On       : Thu Aug 04 18:33:00 2016
// Last Modified By : Aaron B. Moss
// Last Modified On : Thu Aug 04 18:33:00 2016
// Update Count     : 1
//

#include <cassert>
#include <list>
#include <utility>
#include <vector>
#include <unordered_map>

#include "InstantiateGeneric.h"

#include "DeclMutator.h"
#include "GenPoly.h"
#include "ScopedSet.h"
#include "PolyMutator.h"

#include "ResolvExpr/typeops.h"

#include "SynTree/Declaration.h"
#include "SynTree/Expression.h"
#include "SynTree/Type.h"

#include "Common/ScopedMap.h"
#include "Common/UniqueName.h"
#include "Common/utility.h"

namespace GenPoly {

        /// Abstracts type equality for a list of parameter types
        struct TypeList {
                TypeList() : params() {}
                TypeList( const std::list< Type* > &_params ) : params() { cloneAll(_params, params); }
                TypeList( std::list< Type* > &&_params ) : params( _params ) {}

                TypeList( const TypeList &that ) : params() { cloneAll(that.params, params); }
                TypeList( TypeList &&that ) : params( std::move( that.params ) ) {}

                /// Extracts types from a list of TypeExpr*
                TypeList( const std::list< TypeExpr* >& _params ) : params() {
                        for ( std::list< TypeExpr* >::const_iterator param = _params.begin(); param != _params.end(); ++param ) {
                                params.push_back( (*param)->get_type()->clone() );
                        }
                }

                TypeList& operator= ( const TypeList &that ) {
                        deleteAll( params );

                        params.clear();
                        cloneAll( that.params, params );

                        return *this;
                }

                TypeList& operator= ( TypeList &&that ) {
                        deleteAll( params );

                        params = std::move( that.params );

                        return *this;
                }

                ~TypeList() { deleteAll( params ); }

                bool operator== ( const TypeList& that ) const {
                        if ( params.size() != that.params.size() ) return false;

                        SymTab::Indexer dummy;
                        for ( std::list< Type* >::const_iterator it = params.begin(), jt = that.params.begin(); it != params.end(); ++it, ++jt ) {
                                if ( ! ResolvExpr::typesCompatible( *it, *jt, dummy ) ) return false;
                        }
                        return true;
                }

                std::list< Type* > params;  ///< Instantiation parameters
        };

        /// Maps a key and a TypeList to the some value, accounting for scope
        template< typename Key, typename Value >
        class InstantiationMap {
                /// Wraps value for a specific (Key, TypeList) combination
                typedef std::pair< TypeList, Value* > Instantiation;
                /// List of TypeLists paired with their appropriate values
                typedef std::vector< Instantiation > ValueList;
                /// Underlying map type; maps keys to a linear list of corresponding TypeLists and values
                typedef ScopedMap< Key*, ValueList > InnerMap;

                InnerMap instantiations;  ///< instantiations

        public:
                /// Starts a new scope
                void beginScope() { instantiations.beginScope(); }

                /// Ends a scope
                void endScope() { instantiations.endScope(); }

                /// Gets the value for the (key, typeList) pair, returns NULL on none such.
                Value *lookup( Key *key, const std::list< TypeExpr* >& params ) const {
                        TypeList typeList( params );

                        // scan scopes for matches to the key
                        for ( typename InnerMap::const_iterator insts = instantiations.find( key ); insts != instantiations.end(); insts = instantiations.findNext( insts, key ) ) {
                                for ( typename ValueList::const_reverse_iterator inst = insts->second.rbegin(); inst != insts->second.rend(); ++inst ) {
                                        if ( inst->first == typeList ) return inst->second;
                                }
                        }
                        // no matching instantiations found
                        return 0;
                }

                /// Adds a value for a (key, typeList) pair to the current scope
                void insert( Key *key, const std::list< TypeExpr* > &params, Value *value ) {
                        auto it = instantiations.findAt( instantiations.currentScope(), key );
                        if ( it == instantiations.end() ) {
                                instantiations.insert( key, ValueList{ Instantiation{ TypeList( params ), value } } );
                        } else {
                                it->second.push_back( Instantiation{ TypeList( params ), value } );
                        }
                }
        };

        /// Possible options for a given specialization of a generic type
        enum class genericType {
                dtypeStatic,  ///< Concrete instantiation based solely on {d,f}type-to-void conversions
                concrete,     ///< Concrete instantiation requiring at least one parameter type
                dynamic       ///< No concrete instantiation
        };

        genericType& operator |= ( genericType& gt, const genericType& ht ) {
                switch ( gt ) {
                case genericType::dtypeStatic:
                        gt = ht;
                        break;
                case genericType::concrete:
                        if ( ht == genericType::dynamic ) { gt = genericType::dynamic; }
                        break;
                case genericType::dynamic:
                        // nothing possible
                        break;
                }
                return gt;
        }

        // collect the environments of each TypeInstType so that type variables can be replaced
        // xxx - possibly temporary solution. Access to type environments is required in GenericInstantiator, but it needs to be a DeclMutator which does not provide easy access to the type environments.
        class EnvFinder final : public GenPoly::PolyMutator {
        public:
                using GenPoly::PolyMutator::mutate;
                virtual Type * mutate( TypeInstType * inst ) override {
                        if ( env ) envMap[inst] = env;
                        return inst;
                }

                // don't want to associate an environment with TypeInstTypes that occur in function types - this may actually only apply to function types belonging to DeclarationWithTypes (or even just FunctionDecl)?
                virtual Type * mutate( FunctionType * ftype ) override {
                        return ftype;
                }
                std::unordered_map< ReferenceToType *, TypeSubstitution * > envMap;
        };

        /// Mutator pass that replaces concrete instantiations of generic types with actual struct declarations, scoped appropriately
        class GenericInstantiator final : public DeclMutator {
                /// Map of (generic type, parameter list) pairs to concrete type instantiations
                InstantiationMap< AggregateDecl, AggregateDecl > instantiations;
                /// Set of types which are dtype-only generic (and therefore have static layout)
                ScopedSet< AggregateDecl* > dtypeStatics;
                /// Namer for concrete types
                UniqueName typeNamer;
                /// Reference to mapping of environments
                const std::unordered_map< ReferenceToType *, TypeSubstitution * > & envMap;
        public:
                GenericInstantiator( const std::unordered_map< ReferenceToType *, TypeSubstitution * > & envMap ) : DeclMutator(), instantiations(), dtypeStatics(), typeNamer("_conc_"), envMap( envMap ) {}

                using DeclMutator::mutate;
                virtual Type* mutate( StructInstType *inst ) override;
                virtual Type* mutate( UnionInstType *inst ) override;

                virtual void doBeginScope() override;
                virtual void doEndScope() override;
        private:
                /// Wrap instantiation lookup for structs
                StructDecl* lookup( StructInstType *inst, const std::list< TypeExpr* > &typeSubs ) { return (StructDecl*)instantiations.lookup( inst->get_baseStruct(), typeSubs ); }
                /// Wrap instantiation lookup for unions
                UnionDecl* lookup( UnionInstType *inst, const std::list< TypeExpr* > &typeSubs ) { return (UnionDecl*)instantiations.lookup( inst->get_baseUnion(), typeSubs ); }
                /// Wrap instantiation insertion for structs
                void insert( StructInstType *inst, const std::list< TypeExpr* > &typeSubs, StructDecl *decl ) { instantiations.insert( inst->get_baseStruct(), typeSubs, decl ); }
                /// Wrap instantiation insertion for unions
                void insert( UnionInstType *inst, const std::list< TypeExpr* > &typeSubs, UnionDecl *decl ) { instantiations.insert( inst->get_baseUnion(), typeSubs, decl ); }

                void replaceParametersWithConcrete( std::list< Expression* >& params );
                Type *replaceWithConcrete( Type *type, bool doClone );

                /// Strips a dtype-static aggregate decl of its type parameters, marks it as stripped
                void stripDtypeParams( AggregateDecl *base, std::list< TypeDecl* >& baseParams, const std::list< TypeExpr* >& typeSubs );
        };

        void instantiateGeneric( std::list< Declaration* > &translationUnit ) {
                EnvFinder finder;
                mutateAll( translationUnit, finder );
                GenericInstantiator instantiator( finder.envMap );
                instantiator.mutateDeclarationList( translationUnit );
        }

        /// Makes substitutions of params into baseParams; returns dtypeStatic if there is a concrete instantiation based only on {d,f}type-to-void conversions,
        /// concrete if there is a concrete instantiation requiring at least one parameter type, and dynamic if there is no concrete instantiation
        genericType makeSubstitutions( const std::list< TypeDecl* >& baseParams, const std::list< Expression* >& params, std::list< TypeExpr* >& out ) {
                genericType gt = genericType::dtypeStatic;

                // substitute concrete types for given parameters, and incomplete types for placeholders
                std::list< TypeDecl* >::const_iterator baseParam = baseParams.begin();
                std::list< Expression* >::const_iterator param = params.begin();
                for ( ; baseParam != baseParams.end() && param != params.end(); ++baseParam, ++param ) {
                        TypeExpr *paramType = dynamic_cast< TypeExpr* >( *param );
                        assert(paramType && "Aggregate parameters should be type expressions");

                        if ( (*baseParam)->isComplete() ) {
                                // substitute parameter for complete (otype or sized dtype) type; makes the struct concrete or dynamic depending on the parameter
                                out.push_back( paramType->clone() );
                                gt |= isPolyType( paramType->get_type() ) ? genericType::dynamic : genericType::concrete;
                        } else switch ( (*baseParam)->get_kind() ) {
                                case TypeDecl::Dtype:
                                        // can pretend that any incomplete dtype is `void`
                                        out.push_back( new TypeExpr( new VoidType( Type::Qualifiers() ) ) );
                                        break;
                                case TypeDecl::Ftype:
                                        // can pretend that any ftype is `void (*)(void)`
                                        out.push_back( new TypeExpr( new FunctionType( Type::Qualifiers(), false ) ) );
                                        break;
                                case TypeDecl::Ttype:
                                        assertf( false, "Ttype parameters are not currently allowed as parameters to generic types." );
                                        break;
                                case TypeDecl::Any:
                                        assertf( false, "otype parameters handled by baseParam->isComplete()." );
                                        break;
                        }
                }

                assert( baseParam == baseParams.end() && param == params.end() && "Type parameters should match type variables" );
                return gt;
        }

        /// Substitutes types of members of in according to baseParams => typeSubs, appending the result to out
        void substituteMembers( const std::list< Declaration* >& in, const std::list< TypeDecl* >& baseParams, const std::list< TypeExpr* >& typeSubs,
                                                        std::list< Declaration* >& out ) {
                // substitute types into new members
                TypeSubstitution subs( baseParams.begin(), baseParams.end(), typeSubs.begin() );
                for ( std::list< Declaration* >::const_iterator member = in.begin(); member != in.end(); ++member ) {
                        Declaration *newMember = (*member)->clone();
                        subs.apply(newMember);
                        out.push_back( newMember );
                }
        }

        /// Substitutes types of members according to baseParams => typeSubs, working in-place
        void substituteMembers( std::list< Declaration* >& members, const std::list< TypeDecl* >& baseParams, const std::list< TypeExpr* >& typeSubs ) {
                // substitute types into new members
                TypeSubstitution subs( baseParams.begin(), baseParams.end(), typeSubs.begin() );
                for ( std::list< Declaration* >::iterator member = members.begin(); member != members.end(); ++member ) {
                        subs.apply(*member);
                }
        }

        /// Strips the instances's type parameters
        void stripInstParams( ReferenceToType *inst ) {
                deleteAll( inst->get_parameters() );
                inst->get_parameters().clear();
        }

        void GenericInstantiator::stripDtypeParams( AggregateDecl *base, std::list< TypeDecl* >& baseParams, const std::list< TypeExpr* >& typeSubs ) {
                substituteMembers( base->get_members(), baseParams, typeSubs );

                deleteAll( baseParams );
                baseParams.clear();

                dtypeStatics.insert( base );
        }

        /// xxx - more or less copied from box -- these should be merged with those somehow...
        void GenericInstantiator::replaceParametersWithConcrete( std::list< Expression* >& params ) {
                for ( std::list< Expression* >::iterator param = params.begin(); param != params.end(); ++param ) {
                        TypeExpr *paramType = dynamic_cast< TypeExpr* >( *param );
                        assertf(paramType, "Aggregate parameters should be type expressions");
                        paramType->set_type( replaceWithConcrete( paramType->get_type(), false ) );
                }
        }

        Type *GenericInstantiator::replaceWithConcrete( Type *type, bool doClone ) {
                if ( TypeInstType *typeInst = dynamic_cast< TypeInstType * >( type ) ) {
                        if ( envMap.count( typeInst ) ) {
                                TypeSubstitution * env = envMap.at( typeInst );
                                Type *concrete = env->lookup( typeInst->get_name() );
                                if ( concrete ) {
                                        return concrete->clone();
                                }
                                else return typeInst->clone();
                        }
                } else if ( StructInstType *structType = dynamic_cast< StructInstType* >( type ) ) {
                        if ( doClone ) {
                                structType = structType->clone();
                        }
                        replaceParametersWithConcrete( structType->get_parameters() );
                        return structType;
                } else if ( UnionInstType *unionType = dynamic_cast< UnionInstType* >( type ) ) {
                        if ( doClone ) {
                                unionType = unionType->clone();
                        }
                        replaceParametersWithConcrete( unionType->get_parameters() );
                        return unionType;
                }
                return type;
        }


        Type* GenericInstantiator::mutate( StructInstType *inst ) {
                // mutate subtypes
                Type *mutated = Mutator::mutate( inst );
                inst = dynamic_cast< StructInstType* >( mutated );
                if ( ! inst ) return mutated;

                // exit early if no need for further mutation
                if ( inst->get_parameters().empty() ) return inst;

                // need to replace type variables to ensure that generic types are instantiated for the return values of polymorphic functions (in particular, for thunks, because they are not [currently] copy constructed).
                replaceWithConcrete( inst, false );

                // check for an already-instantiatiated dtype-static type
                if ( dtypeStatics.find( inst->get_baseStruct() ) != dtypeStatics.end() ) {
                        stripInstParams( inst );
                        return inst;
                }

                // check if type can be concretely instantiated; put substitutions into typeSubs
                assertf( inst->get_baseParameters(), "Base struct has parameters" );
                std::list< TypeExpr* > typeSubs;
                genericType gt = makeSubstitutions( *inst->get_baseParameters(), inst->get_parameters(), typeSubs );
                switch ( gt ) {
                case genericType::dtypeStatic:
                        stripDtypeParams( inst->get_baseStruct(), *inst->get_baseParameters(), typeSubs );
                        stripInstParams( inst );
                        break;

                case genericType::concrete: {
                        // make concrete instantiation of generic type
                        StructDecl *concDecl = lookup( inst, typeSubs );
                        if ( ! concDecl ) {
                                // set concDecl to new type, insert type declaration into statements to add
                                concDecl = new StructDecl( typeNamer.newName( inst->get_name() ) );
                                concDecl->set_body( inst->get_baseStruct()->has_body() );
                                substituteMembers( inst->get_baseStruct()->get_members(), *inst->get_baseParameters(), typeSubs,        concDecl->get_members() );
                                DeclMutator::addDeclaration( concDecl );
                                insert( inst, typeSubs, concDecl );
                        }
                        StructInstType *newInst = new StructInstType( inst->get_qualifiers(), concDecl->get_name() );
                        newInst->set_baseStruct( concDecl );

                        delete inst;
                        inst = newInst;
                        break;
                }

                case genericType::dynamic:
                        // do nothing
                        break;
                }

                deleteAll( typeSubs );
                return inst;
        }

        Type* GenericInstantiator::mutate( UnionInstType *inst ) {
                // mutate subtypes
                Type *mutated = Mutator::mutate( inst );
                inst = dynamic_cast< UnionInstType* >( mutated );
                if ( ! inst ) return mutated;

                // exit early if no need for further mutation
                if ( inst->get_parameters().empty() ) return inst;

                // check for an already-instantiatiated dtype-static type
                if ( dtypeStatics.find( inst->get_baseUnion() ) != dtypeStatics.end() ) {
                        stripInstParams( inst );
                        return inst;
                }

                // check if type can be concretely instantiated; put substitutions into typeSubs
                assert( inst->get_baseParameters() && "Base union has parameters" );
                std::list< TypeExpr* > typeSubs;
                genericType gt = makeSubstitutions( *inst->get_baseParameters(), inst->get_parameters(), typeSubs );
                switch ( gt ) {
                case genericType::dtypeStatic:
                        stripDtypeParams( inst->get_baseUnion(), *inst->get_baseParameters(), typeSubs );
                        stripInstParams( inst );
                        break;

                case genericType::concrete:
                {
                        // make concrete instantiation of generic type
                        UnionDecl *concDecl = lookup( inst, typeSubs );
                        if ( ! concDecl ) {
                                // set concDecl to new type, insert type declaration into statements to add
                                concDecl = new UnionDecl( typeNamer.newName( inst->get_name() ) );
                                concDecl->set_body( inst->get_baseUnion()->has_body() );
                                substituteMembers( inst->get_baseUnion()->get_members(), *inst->get_baseParameters(), typeSubs, concDecl->get_members() );
                                DeclMutator::addDeclaration( concDecl );
                                insert( inst, typeSubs, concDecl );
                        }
                        UnionInstType *newInst = new UnionInstType( inst->get_qualifiers(), concDecl->get_name() );
                        newInst->set_baseUnion( concDecl );

                        delete inst;
                        inst = newInst;
                        break;
                }
                case genericType::dynamic:
                        // do nothing
                        break;
                }

                deleteAll( typeSubs );
                return inst;
        }

        void GenericInstantiator::doBeginScope() {
                DeclMutator::doBeginScope();
                instantiations.beginScope();
                dtypeStatics.beginScope();
        }

        void GenericInstantiator::doEndScope() {
                DeclMutator::doEndScope();
                instantiations.endScope();
                dtypeStatics.endScope();
        }

} // namespace GenPoly

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