Changeset 184557e

Timestamp:

Jul 6, 2018, 5:10:14 PM (6 years ago)

Author:

Aaron Moss <a3moss@…>

Branches:

new-env

Children:

5c14030

Parents:

b21c77a

Message:

First draft of persistent-hash-based TypeEnvironment?

Location:

src

Files:

• Common/PersistentDisjointSet.h (modified) (3 diffs)
• Common/PersistentMap.h (modified) (2 diffs)
• Common/option.h (added)
• ResolvExpr/TypeEnvironment.cc (modified) (5 diffs)
• ResolvExpr/TypeEnvironment.h (modified) (9 diffs)

src/Common/PersistentDisjointSet.h

@@ -128 +128 @@
                 }
         }
+
+        /// Non-initializing constructor; should call init() before use
+        PersistentDisjointSet( Mode m ) : data(), mode(m) {}
 
         PersistentDisjointSet( Mode m, Base&& b ) : data(), mode(m) {
@@ -291 +294 @@
         size_type count(Elm i) const { return rerooted().count( i ); }
 
-        /// Finds root for element i, assertfs i is present
+        /// Finds root for element i, undefined behaviour if i is not present
         Elm find(Elm i) const {
                 const Base& self = rerooted();
@@ -375 +378 @@
         }
 
-        /// Reports all members of a class to `out`; none if i does not exist in map
-        template<typename OutputIterator>
-        void find_class(Elm i, OutputIterator&& out) const {
+private:
+        /// Removes the children of the tree rooted at `root` as `root_node`, returning a new 
+        /// uninitialized node and editing `next_edit` to point toward this new node.
+        static Self* remove_children(Elm root, Node& root_node, Base& base_map, Self* next_edit) {
+                // Invariant: root.next is *always* a pointer to a leaf of the most-recently added
+                // subtree.
+                //
+                // Proof: By induction on height:
+                // * height == 0: root.next == root, trivially true
+                // * added.height < root.height: true by ind. hyp.
+                // * added.height == root.height: no node may have a child the same height, ergo 
+                //   property holds for added, therefore root.
+                //
+                // Corollary: next of most-recently-added subtree root is previously added subtree
+
+                // remove all subtrees
+                while ( root != root_node.next ) {
+                        // find added child
+                        auto it = base_map.find( root_node.next );
+                        while ( it->second.parent != root ) it = base_map.find( it->second.parent );
+                        Elm added = it->first;
+                        Node& added_node = it->second;
+
+                        // unlink subtree and set up previous map as ADDTO new map
+                        std::swap( root_node.next, added_node.next );
+                        Self* new_edit = new Self{ BASE };
+                        next_edit->init<AddTo>( new_edit, root, added, false );  // assume unchanged root height
+                        next_edit->mode = ADDTO;
+
+                        // remove subtree children from map
+                        next_edit = remove_children( added, added_node, base_map, new_edit );
+
+                        // remove subtree root from map and set up previous map as ADD to new map
+                        base_map.erase( added );
+                        new_edit = new Self{ BASE };
+                        next_edit->init<Add>( new_edit, added );
+                        next_edit->mode = ADD;
+
+                        next_edit = new_edit;
+                }
+
+                return next_edit;
+        }
+
+public:
+        /// Removes all elements of a class given by its root; returns updated map.
+        Self* remove_class(Elm root) {
+                reroot();
+
+                // remove map from self
+                Base base_map = take_as<Base>();
+                reset_as_base();
+
+                // find root node and remove children
+                auto it = base_map.find( root );
+                assertf(it != base_map.end(), "root node must exist in map");
+                Self* next_edit = remove_children( root, it->second, base_map, this);
+
+                // root is alone in class, remove from map
+                base_map.erase( root );
+                Self* ret = new Self{ BASE, std::move(base_map) };
+                // reinitialize previous node as ADD to new map
+                next_edit->init<Add>( ret, root );
+                next_edit->mode = ADD;
+
+                return ret;
+        }
+
+        /// Applies `f` to all members of a class containing `i` (undefined behaviour if not present).
+        /// `f` should take members by const reference or copy
+        template<typename F>
+        void apply_to_class(Elm i, F&& f) const {
                 const Base& self = rerooted();
-
-                // skip empty classes
-                if ( ! self.count( i ) ) return;
 
                 Elm crnt = i;
                 do {
-                        *out++ = crnt;
+                        f( crnt );
                         auto it = self.find( crnt );
                         assertf( it != self.end(), "current node must exist in base" );

src/Common/PersistentMap.h

@@ -114 +114 @@
         }
 
+        /// Non-initializing constructor; should call init() before use
+        PersistentMap( Mode m ) : data(), mode(m) {}
+
         PersistentMap( Mode m, Base&& b ) : data(), mode(m) {
                 assertf(m == BASE, "invalid mode");
@@ -420 +423 @@
                 }
         }
+
+        /// Applies the function `f` to all elements of the map, returning a pointer to the updated map.
+        /// `f` should take two parameters, `const Key&` and `Val&`, returning option<Val> filled with 
+        /// the previous value if mutated, an empty option<Val> otherwise.
+        /// NOTE: when porting to C++17, this should work fine with std::optional
+        template<typename F>
+        Self* apply_to_all(F&& f) {
+                // reset to root and exit early if no change
+                if ( rerooted().empty() ) return this;
+
+                // remove map from self
+                Base base_map = take_as<Base>();
+                reset_as_base();
+
+                // apply all edits
+                Self* next_edit = this;
+                for ( auto& entry : base_map ) {
+                        auto res = f( entry.first, entry.second );
+                        if ( res ) {
+                                // entry has been mutated; reset next_edit node as mutation
+                                Self* new_node = new Self{ BASE };
+                                next_edit->init<Ins>( new_node, entry.first, *std::move(res) );
+                                next_edit->mode = UPD;
+                                next_edit = new_node;
+                        }
+                }
+
+                // set map into final node and return
+                next_edit->init<Base>( std::move(base_map) );
+                return next_edit;
+        }
+
+        /// Applies the function `f` to all elements of the map.
+        /// `f` should take two parameters, `const Key&` and `const Val&`.
+        template<typename F>
+        void apply_to_all(F&& f) const {
+                for ( const auto& entry : rerooted() ) { f( entry.first, entry.second ); }
+        }
 };
 

src/ResolvExpr/TypeEnvironment.cc

@@ -21 +21 @@
 #include "Common/InternedString.h"     // for interned_string
 #include "Common/PassVisitor.h"        // for PassVisitor<GcTracer>
+#include "Common/option.h"             // for option<T>
 #include "Common/utility.h"            // for maybeClone
 #include "SymTab/Indexer.h"            // for Indexer
@@ -49 +50 @@
         }
 
-#if 0
-        void EqvClass::initialize( const EqvClass &src, EqvClass &dest ) {
-                initialize( src, dest, src.type );
-        }
-
-        void EqvClass::initialize( const EqvClass &src, EqvClass &dest, const Type *ty ) {
-                dest.vars = src.vars;
-                dest.type = maybeClone( ty );
-                dest.allowWidening = src.allowWidening;
-                dest.data = src.data;
-        }
-
-        EqvClass::EqvClass() : type( nullptr ), allowWidening( true ) {
-        }
-
-        EqvClass::EqvClass( const EqvClass &other ) {
-                initialize( other, *this );
-        }
-
-        EqvClass::EqvClass( const EqvClass &other, const Type *ty ) {
-                initialize( other, *this, ty );
-        }
-
-        EqvClass::EqvClass( EqvClass &&other ) 
-        : vars{std::move(other.vars)}, type{other.type}, 
-          allowWidening{std::move(other.allowWidening)}, data{std::move(other.data)} {
-                  other.type = nullptr;
-        }
-
-        EqvClass &EqvClass::operator=( const EqvClass &other ) {
-                if ( this == &other ) return *this;
-                initialize( other, *this );
-                return *this;
-        }
-
-        EqvClass &EqvClass::operator=( EqvClass &&other ) {
-                if ( this == &other ) return *this;
-                
-                vars = std::move(other.vars);
-                type = other.type;
-                allowWidening = std::move(other.allowWidening);
-                data = std::move(other.data);
-
-                return *this;
-        }
-
-        void EqvClass::set_type( Type* ty ) { type = ty; }
-
-        void EqvClass::print( std::ostream &os, Indenter indent ) const {
-                os << "( ";
-                std::copy( vars.begin(), vars.end(), std::ostream_iterator< std::string >( os, " " ) );
-                os << ")";
-                if ( type ) {
-                        os << " -> ";
-                        type->print( os, indent+1 );
-                } // if
-                if ( ! allowWidening ) {
-                        os << " (no widening)";
-                } // if
-                os << std::endl;
-        }
-
-        const EqvClass* TypeEnvironment::lookup( const std::string &var ) const {
-                for ( std::list< EqvClass >::const_iterator i = env.begin(); i != env.end(); ++i ) {
-                        if ( i->vars.find( var ) != i->vars.end() ) return &*i;
-                } // for
-                return nullptr;
-        }
-#endif
-
         std::pair<interned_string, interned_string> TypeEnvironment::mergeClasses( 
                         interned_string root1, interned_string root2 ) {
@@ -126 +57 @@
                 // determine new root
                 assertf(classes->get_mode() == Classes::REMFROM, "classes updated to REMFROM by merge");
-                auto ret = std::make_pair( classes->get_root(), classes->get_child );
+                auto ret = std::make_pair( classes->get_root(), classes->get_child() );
                 
                 // finalize classes
@@ -302 +233 @@
         }
 
-#if !1
-        /// Removes any class from env that intersects eqvClass
-        void filterOverlappingClasses( std::list<EqvClass> &env, const EqvClass &eqvClass ) {
-                for ( auto i = env.begin(); i != env.end(); ) {
-                        auto next = i;
-                        ++next;
-                        std::set<std::string> intersection;
-                        std::set_intersection( i->vars.begin(), i->vars.end(), eqvClass.vars.begin(), eqvClass.vars.end(), 
-                                std::inserter( intersection, intersection.begin() ) );
-                        if ( ! intersection.empty() ) { env.erase( i ); }
-                        i = next;
-                }
-        }
-
-        void TypeEnvironment::add( EqvClass &&eqvClass ) {
-                filterOverlappingClasses( env, eqvClass );
-                env.push_back( std::move(eqvClass) );
-        }
-
         void TypeEnvironment::add( const Type::ForallList &tyDecls ) {
                 for ( Type::ForallList::const_iterator i = tyDecls.begin(); i != tyDecls.end(); ++i ) {
-                        EqvClass newClass;
-                        newClass.vars.insert( (*i)->get_name() );
-                        newClass.data = TypeDecl::Data{ (*i) };
-                        env.push_back( std::move(newClass) );
+                        interned_string name = (*i)->get_name();
+                        classes = classes->add( name );
+                        bindings = bindings->set( name, *i );
                 } // for
         }
 
         void TypeEnvironment::add( const TypeSubstitution & sub ) {
-                EqvClass newClass;
+                interned_string not_found{nullptr};
+
                 for ( auto p : sub ) {
-                        newClass.vars.insert( p.first );
-                        newClass.type = p.second->clone();
-                        newClass.allowWidening = false;
+                        interned_string var = p.first;
+                        
+                        // filter overlapping classes out of existing environment
+                        // (this is a very shady assumption, but has worked for a long time...)
+                        interned_string root = classes->find_or_default( v, not_found );
+                        if ( root != not_found ) {
+                                classes = classes->remove_class( root );
+                                bindings = bindings->erase( root );
+                        }
+
                         // Minimal assumptions. Not technically correct, but might be good enough, and
                         // is the best we can do at the moment since information is lost in the
                         // transition to TypeSubstitution
-                        newClass.data = TypeDecl::Data{ TypeDecl::Dtype, false };
-                        add( std::move(newClass) );
+                        TypeDecl::Data data{ TypeDecl::Dtype, false };
+
+                        // add variable to class and bindings
+                        classes = classes->add( var );
+                        bindings = bindings->set( var, BoundType{ p.second->clone, false, data } );
                 }
         }
 
         void TypeEnvironment::makeSubstitution( TypeSubstitution &sub ) const {
-                for ( std::list< EqvClass >::const_iterator theClass = env.begin(); theClass != env.end(); ++theClass ) {
-                        for ( std::set< std::string >::const_iterator theVar = theClass->vars.begin(); theVar != theClass->vars.end(); ++theVar ) {
-                                if ( theClass->type ) {
-                                        sub.add( *theVar, theClass->type );
-                                } else if ( theVar != theClass->vars.begin() ) {
-                                        TypeInstType *newTypeInst = new TypeInstType( Type::Qualifiers(), *theClass->vars.begin(), theClass->data.kind == TypeDecl::Ftype );
-                                        sub.add( *theVar, newTypeInst );
-                                } // if
-                        } // for
-                } // for
+                bindings->apply_to_all([classes, &sub]( interned_string root, const BoundType& bound ){
+                        classes->apply_to_class(root, [&]( interned_string var ) {
+                                if ( bound.type ) {
+                                        sub.add( var, bound.type );
+                                } else if ( var != root ) {
+                                        sub.add( var, new TypeInstType{ 
+                                                Type::Qualifiers{}, root, bound.data.kind == TypeDecl::Ftype } );
+                                }
+                        });
+                });
+
                 sub.normalize();
         }
 
         void TypeEnvironment::print( std::ostream &os, Indenter indent ) const {
-                for ( const EqvClass & theClass : env ) {
-                        theClass.print( os, indent );
-                } // for
-        }
-
-        std::list< EqvClass >::iterator TypeEnvironment::internal_lookup( const std::string &var ) {
-                for ( std::list< EqvClass >::iterator i = env.begin(); i != env.end(); ++i ) {
-                        if ( i->vars.count( var ) ) return i;
-                } // for
-                return env.end();
-        }
-
-        void TypeEnvironment::simpleCombine( const TypeEnvironment &second ) {
-                env.insert( env.end(), second.env.begin(), second.env.end() );
+                bindings->apply_to_all([classes,&]( interned_string root, const BoundType& bound ) {
+                        os << "( ";
+                        classes->apply_to_class( root, [&os]( interned_string var ) { os << var << " "; } );
+                        os << ")";
+                        if ( bound.type ) {
+                                os << " -> ";
+                                type->print( os, indent+1 );
+                        }
+                        if ( ! bound.allowWidening ) {
+                                os << " (no widening)";
+                        }
+                        os << std::endl;
+                });
+        }
+
+        void TypeEnvironment::simpleCombine( const TypeEnvironment &o ) {
+                o.bindings->apply_to_all( [&]( interned_string root, const BoundType& bound ) {
+                        // add members of new class
+                        interned_string new_root{nullptr};
+                        o.classes->apply_to_class( root, [this,&new_root]( interned_string var ) {
+                                classes = classes->add( var );
+                                new_root = new_root ? mergeClasses( new_root, var ).first : var;
+                        });
+                        // set binding for new class
+                        bindings = bindings->set( new_root, bound );
+                });
         }
 
         void TypeEnvironment::extractOpenVars( OpenVarSet &openVars ) const {
-                for ( std::list< EqvClass >::const_iterator eqvClass = env.begin(); eqvClass != env.end(); ++eqvClass ) {
-                        for ( std::set< std::string >::const_iterator var = eqvClass->vars.begin(); var != eqvClass->vars.end(); ++var ) {
-                                openVars[ *var ] = eqvClass->data;
-                        } // for
-                } // for
+                bindings->apply_to_all( [classes,&openVars]( interned_string root, const BoundType& bound ) {
+                        classes->apply_to_class( root, [&openVars,&bound]( interned_string var ) {
+                                openVars[ var ] = bound.data;
+                        } );
+                } );
         }
 
         void TypeEnvironment::addActual( const TypeEnvironment& actualEnv, OpenVarSet& openVars ) {
-                for ( const EqvClass& c : actualEnv ) {
-                        EqvClass c2 = c;
-                        c2.allowWidening = false;
-                        for ( const std::string& var : c2.vars ) {
-                                openVars[ var ] = c2.data;
-                        }
-                        env.push_back( std::move(c2) );
-                }
+                actualEnv.bindings->apply_to_all( [&]( interned_string root, const BoundType& bound ) {
+                        // add members of new class, setting openVars concurrently
+                        interned_string new_root{nullptr};
+                        actualEnv.classes->apply_to_class( root, [&]( interned_string var ) {
+                                classes = classes->add( var );
+                                new_root = new_root ? mergeClasses( new_root, var ).first : var;
+                                openVars[ var ] = bound.data;
+                        } );
+                        // add new type binding without widening
+                        bindings = bindings->set( new_root, 
+                                BoundType{ maybeClone(bound.type), false, bound.data } );
+                } );
+        }
+
+        void TypeEnvironment::forbidWidening() {
+                bindings = bindings->apply_to_all([]( const interned_string& k, BoundType& c ) {
+                        if ( c.allowWidening ) {
+                                option<BoundType> ret = c;
+                                c.allowWidening = false;
+                                return ret;
+                        } else return option<BoundType>{};
+                });
         }
 
@@ -398 +347 @@
                 return out;
         }
-#endif
 
         PassVisitor<GcTracer> & operator<<( PassVisitor<GcTracer> & gc, const TypeEnvironment & env ) {

src/ResolvExpr/TypeEnvironment.h

@@ -86 +86 @@
                 bool allowWidening;
                 TypeDecl::Data data;
-        };
-
-#if 0
-        /// An equivalence class, with its binding information
-        struct EqvClass {
-                std::set< std::string > vars;
-                Type *type;
-                bool allowWidening;
-                TypeDecl::Data data;
-
-                void initialize( const EqvClass &src, EqvClass &dest );
-                void initialize( const EqvClass &src, EqvClass &dest, const Type *ty );
-                EqvClass();
-                EqvClass( const EqvClass &other );
-                EqvClass( const EqvClass &other, const Type *ty );
-                EqvClass( EqvClass &&other );
-                EqvClass &operator=( const EqvClass &other );
-                EqvClass &operator=( EqvClass &&other );
-                void print( std::ostream &os, Indenter indent = {} ) const;
-
-                /// Takes ownership of `ty`, freeing old `type`
-                void set_type(Type* ty);
-        };
-#endif
-        
+
+                BoundType() = default;
+                BoundType( TypeDecl* td ) : type{nullptr}, allowWidening{true}, data{td} {}
+                BoundType( Type* ty, bool aw, const TypeDecl::Data& td )
+                        : type{ty}, allowWidening{aw}, data{td} {}
+                BoundType( const BoundType& o )
+                        : type{maybeClone(o.type)}, allowWidening{o.allowWidening}, data{o.data} {}
+                BoundType( BoundType&& o ) = default;
+                BoundType& operator= (const BoundType& o) {
+                        if ( this == &o ) return *this;
+                        type = maybeClone( o.type );
+                        allowWidening = o.allowWidening;
+                        data = o.data;
+                        return *this;
+                }
+                BoundType& operator= (BoundType&& o) = default;
+        };
+
         class TypeEnvironment;
 
@@ -137 +130 @@
                 /// Gets the bound type information of the referenced equivalence class, default if none
                 inline BoundType get_bound() const;
-
-#if 0
-                /// Gets the referenced equivalence class
-                inline EqvClass get_class() const;
-                EqvClass operator* () const { return get_class(); }
-#endif
 
                 // Check that there is a referenced typeclass
@@ -171 +158 @@
                         interned_string root1, interned_string root2 );
 
-          public:
+        public:
                 class iterator : public std::iterator<
                                 std::forward_iterator_tag, 
@@ -213 +200 @@
                         AssertionSet& need, AssertionSet& have, const OpenVarSet& openVars, 
                         WidenMode widenMode, const SymTab::Indexer& indexer );
-#if !1
-        private:
-                void add( EqvClass &&eqvClass );
+
         public:
                 void add( const Type::ForallList &tyDecls );
@@ -222 +207 @@
                 template< typename SynTreeClass > int applyFree( SynTreeClass *&type ) const;
                 void makeSubstitution( TypeSubstitution &result ) const;
-#endif
                 bool isEmpty() const { return classes->empty(); }
-#if !1
                 void print( std::ostream &os, Indenter indent = {} ) const;
+        
+                /// Combines two environments without checking invariants.
+                /// Caller should ensure environments do not share type variables.
                 void simpleCombine( const TypeEnvironment &second );
+        
                 void extractOpenVars( OpenVarSet &openVars ) const;
-#endif
                 TypeEnvironment *clone() const { return new TypeEnvironment( *this ); }
 
-#if !1
                 /// Iteratively adds the environment of a new actual (with allowWidening = false),
                 /// and extracts open variables.
@@ -238 +223 @@
                 /// Disallows widening for all bindings in the environment
                 void forbidWidening();
-#endif
 
                 iterator begin() { return { this, bindings->begin() }; }
@@ -244 +228 @@
         };
 
-        void ClassRef::update_root() { return root = env->classes->find( root ); }
+        interned_string ClassRef::update_root() { return root = env->classes->find( root ); }
 
         template<typename T>
         T ClassRef::get_vars() const {
                 T vars;
-                env->classes->find_class( root, std::inserter(vars, vars.end()) );
+                if ( ! env->classes->count( root ) ) return vars;
+                env->classes->apply_to_class( root, [&vars]( interned_string var ) {
+                        vars.insert( vars.end(), var );
+                } );
                 return vars;
         }
@@ -256 +243 @@
                 return env->bindings->get_or_default( root, BoundType{} );
         }
-
-#if 0
-        EqvClass ClassRef::get_class() const { return { get_vars(), get_bound() }; }
-#endif
 
         template< typename SynTreeClass >
@@ -275 +258 @@
         }
 
-#if !1
         std::ostream & operator<<( std::ostream & out, const TypeEnvironment & env );
-#endif
 
         PassVisitor<GcTracer> & operator<<( PassVisitor<GcTracer> & gc, const TypeEnvironment & env );