LLVM API Documentation

SymbolTable.h

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00001 //===-- llvm/SymbolTable.h - Implement a type plane'd symtab ----*- C++ -*-===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and re-written by Reid
00006 // Spencer. It is distributed under the University of Illinois Open Source
00007 // License. See LICENSE.TXT for details.
00008 //
00009 //===----------------------------------------------------------------------===//
00010 //
00011 // This file implements the main symbol table for LLVM.
00012 //
00013 //===----------------------------------------------------------------------===//
00014 
00015 #ifndef LLVM_SYMBOL_TABLE_H
00016 #define LLVM_SYMBOL_TABLE_H
00017 
00018 #include "llvm/Value.h"
00019 #include <map>
00020 
00021 namespace llvm {
00022 
00023 /// This class provides a symbol table of name/value pairs that is broken
00024 /// up by type. For each Type* there is a "plane" of name/value pairs in
00025 /// the symbol table.  Identical types may have overlapping symbol names as
00026 /// long as they are distinct. The SymbolTable also tracks,  separately, a
00027 /// map of name/type pairs. This allows types to be named. Types are treated
00028 /// distinctly from Values.
00029 ///
00030 /// The SymbolTable provides several utility functions for answering common
00031 /// questions about its contents as well as an iterator interface for
00032 /// directly iterating over the contents. To reduce confusion, the terms
00033 /// "type", "value", and "plane" are used consistently. For example,
00034 /// There is a TypeMap typedef that is the mapping of names to Types.
00035 /// Similarly there is a ValueMap typedef that is the mapping of
00036 /// names to Values. Finally, there is a PlaneMap typedef that is the
00037 /// mapping of types to planes of ValueMap. This is the basic structure
00038 /// of the symbol table. When you call type_begin() you're asking
00039 /// for an iterator at the start of the TypeMap. When you call
00040 /// plane_begin(), you're asking for an iterator at the start of
00041 /// the PlaneMap. Finally, when you call value_begin(), you're asking
00042 /// for an iterator at the start of a ValueMap for a specific type
00043 /// plane.
00044 class SymbolTable : public AbstractTypeUser {
00045 
00046 /// @name Types
00047 /// @{
00048 public:
00049 
00050   /// @brief A mapping of names to types.
00051   typedef std::map<const std::string, const Type*> TypeMap;
00052 
00053   /// @brief An iterator over the TypeMap.
00054   typedef TypeMap::iterator type_iterator;
00055 
00056   /// @brief A const_iterator over the TypeMap.
00057   typedef TypeMap::const_iterator type_const_iterator;
00058 
00059   /// @brief A mapping of names to values.
00060   typedef std::map<const std::string, Value *> ValueMap;
00061 
00062   /// @brief An iterator over a ValueMap.
00063   typedef ValueMap::iterator value_iterator;
00064 
00065   /// @brief A const_iterator over a ValueMap.
00066   typedef ValueMap::const_iterator value_const_iterator;
00067 
00068   /// @brief A mapping of types to names to values (type planes).
00069   typedef std::map<const Type *, ValueMap> PlaneMap;
00070 
00071   /// @brief An iterator over the type planes.
00072   typedef PlaneMap::iterator plane_iterator;
00073 
00074   /// @brief A const_iterator over the type planes
00075   typedef PlaneMap::const_iterator plane_const_iterator;
00076 
00077 /// @}
00078 /// @name Constructors
00079 /// @{
00080 public:
00081 
00082   SymbolTable() : LastUnique(0) {}
00083   ~SymbolTable();
00084 
00085 /// @}
00086 /// @name Accessors
00087 /// @{
00088 public:
00089 
00090   /// This method finds the value with the given \p name in the
00091   /// type plane \p Ty and returns it. This method will not find any
00092   /// Types, only Values. Use lookupType to find Types by name.
00093   /// @returns null on failure, otherwise the Value associated with
00094   /// the \p name in type plane \p Ty.
00095   /// @brief Lookup a named, typed value.
00096   Value *lookup(const Type *Ty, const std::string &name) const;
00097 
00098   /// This method finds the type with the given \p name in the
00099   /// type  map and returns it.
00100   /// @returns null if the name is not found, otherwise the Type
00101   /// associated with the \p name.
00102   /// @brief Lookup a type by name.
00103   Type* lookupType(const std::string& name) const;
00104 
00105   /// @returns true iff the type map and the type plane are both not
00106   /// empty.
00107   /// @brief Determine if the symbol table is empty
00108   inline bool isEmpty() const { return pmap.empty() && tmap.empty(); }
00109 
00110   /// @brief The number of name/type pairs is returned.
00111   inline unsigned num_types() const { return unsigned(tmap.size()); }
00112 
00113   /// Given a base name, return a string that is either equal to it or
00114   /// derived from it that does not already occur in the symbol table
00115   /// for the specified type.
00116   /// @brief Get a name unique to this symbol table
00117   std::string getUniqueName(const Type *Ty,
00118                             const std::string &BaseName) const;
00119 
00120   /// This function can be used from the debugger to display the
00121   /// content of the symbol table while debugging.
00122   /// @brief Print out symbol table on stderr
00123   void dump() const;
00124 
00125 /// @}
00126 /// @name Iteration
00127 /// @{
00128 public:
00129 
00130   /// Get an iterator that starts at the beginning of the type planes.
00131   /// The iterator will iterate over the Type/ValueMap pairs in the
00132   /// type planes.
00133   inline plane_iterator plane_begin() { return pmap.begin(); }
00134 
00135   /// Get a const_iterator that starts at the beginning of the type
00136   /// planes.  The iterator will iterate over the Type/ValueMap pairs
00137   /// in the type planes.
00138   inline plane_const_iterator plane_begin() const { return pmap.begin(); }
00139 
00140   /// Get an iterator at the end of the type planes. This serves as
00141   /// the marker for end of iteration over the type planes.
00142   inline plane_iterator plane_end() { return pmap.end(); }
00143 
00144   /// Get a const_iterator at the end of the type planes. This serves as
00145   /// the marker for end of iteration over the type planes.
00146   inline plane_const_iterator plane_end() const { return pmap.end(); }
00147 
00148   /// Get an iterator that starts at the beginning of a type plane.
00149   /// The iterator will iterate over the name/value pairs in the type plane.
00150   /// @note The type plane must already exist before using this.
00151   inline value_iterator value_begin(const Type *Typ) {
00152     assert(Typ && "Can't get value iterator with null type!");
00153     return pmap.find(Typ)->second.begin();
00154   }
00155 
00156   /// Get a const_iterator that starts at the beginning of a type plane.
00157   /// The iterator will iterate over the name/value pairs in the type plane.
00158   /// @note The type plane must already exist before using this.
00159   inline value_const_iterator value_begin(const Type *Typ) const {
00160     assert(Typ && "Can't get value iterator with null type!");
00161     return pmap.find(Typ)->second.begin();
00162   }
00163 
00164   /// Get an iterator to the end of a type plane. This serves as the marker
00165   /// for end of iteration of the type plane.
00166   /// @note The type plane must already exist before using this.
00167   inline value_iterator value_end(const Type *Typ) {
00168     assert(Typ && "Can't get value iterator with null type!");
00169     return pmap.find(Typ)->second.end();
00170   }
00171 
00172   /// Get a const_iterator to the end of a type plane. This serves as the
00173   /// marker for end of iteration of the type plane.
00174   /// @note The type plane must already exist before using this.
00175   inline value_const_iterator value_end(const Type *Typ) const {
00176     assert(Typ && "Can't get value iterator with null type!");
00177     return pmap.find(Typ)->second.end();
00178   }
00179 
00180   /// Get an iterator to the start of the name/Type map.
00181   inline type_iterator type_begin() { return tmap.begin(); }
00182 
00183   /// @brief Get a const_iterator to the start of the name/Type map.
00184   inline type_const_iterator type_begin() const { return tmap.begin(); }
00185 
00186   /// Get an iterator to the end of the name/Type map. This serves as the
00187   /// marker for end of iteration of the types.
00188   inline type_iterator type_end() { return tmap.end(); }
00189 
00190   /// Get a const-iterator to the end of the name/Type map. This serves
00191   /// as the marker for end of iteration of the types.
00192   inline type_const_iterator type_end() const { return tmap.end(); }
00193 
00194   /// This method returns a plane_const_iterator for iteration over
00195   /// the type planes starting at a specific plane, given by \p Ty.
00196   /// @brief Find a type plane.
00197   inline plane_const_iterator find(const Type* Typ) const {
00198     assert(Typ && "Can't find type plane with null type!");
00199     return pmap.find(Typ);
00200   }
00201 
00202   /// This method returns a plane_iterator for iteration over the
00203   /// type planes starting at a specific plane, given by \p Ty.
00204   /// @brief Find a type plane.
00205   inline plane_iterator find(const Type* Typ) {
00206     assert(Typ && "Can't find type plane with null type!");
00207     return pmap.find(Typ);
00208   }
00209 
00210 
00211 /// @}
00212 /// @name Mutators
00213 /// @{
00214 public:
00215 
00216   /// This method will strip the symbol table of its names leaving the type and
00217   /// values.
00218   /// @brief Strip the symbol table.
00219   bool strip();
00220 
00221   /// Inserts a type into the symbol table with the specified name. There can be
00222   /// a many-to-one mapping between names and types. This method allows a type
00223   /// with an existing entry in the symbol table to get a new name.
00224   /// @brief Insert a type under a new name.
00225   void insert(const std::string &Name, const Type *Typ);
00226 
00227   /// Remove a type at the specified position in the symbol table.
00228   /// @returns the removed Type.
00229   Type* remove(type_iterator TI);
00230 
00231 /// @}
00232 /// @name Mutators used by Value::setName and other LLVM internals.
00233 /// @{
00234 public:
00235 
00236   /// This method adds the provided value \p N to the symbol table.  The Value
00237   /// must have both a name and a type which are extracted and used to place the
00238   /// value in the correct type plane under the value's name.
00239   /// @brief Add a named value to the symbol table
00240   inline void insert(Value *Val) {
00241     assert(Val && "Can't insert null type into symbol table!");
00242     assert(Val->hasName() && "Value must be named to go into symbol table!");
00243     insertEntry(Val->getName(), Val->getType(), Val);
00244   }
00245 
00246   /// This method removes a named value from the symbol table. The type and name
00247   /// of the Value are extracted from \p N and used to lookup the Value in the
00248   /// correct type plane. If the Value is not in the symbol table, this method
00249   /// silently ignores the request.
00250   /// @brief Remove a named value from the symbol table.
00251   void remove(Value* Val);
00252 
00253   /// changeName - Given a value with a non-empty name, remove its existing
00254   /// entry from the symbol table and insert a new one for Name.  This is
00255   /// equivalent to doing "remove(V), V->Name = Name, insert(V)", but is faster,
00256   /// and will not temporarily remove the symbol table plane if V is the last
00257   /// value in the symtab with that name (which could invalidate iterators to
00258   /// that plane).
00259   void changeName(Value *V, const std::string &Name);
00260 
00261 /// @}
00262 /// @name Internal Methods
00263 /// @{
00264 private:
00265   /// @brief Insert a value into the symbol table with the specified name.
00266   void insertEntry(const std::string &Name, const Type *Ty, Value *V);
00267 
00268   /// This function is called when one of the types in the type plane
00269   /// is refined.
00270   virtual void refineAbstractType(const DerivedType *OldTy, const Type *NewTy);
00271 
00272   /// This function markes a type as being concrete (defined).
00273   virtual void typeBecameConcrete(const DerivedType *AbsTy);
00274 
00275 /// @}
00276 /// @name Internal Data
00277 /// @{
00278 private:
00279 
00280   /// This is the main content of the symbol table. It provides
00281   /// separate type planes for named values. That is, each named
00282   /// value is organized into a separate dictionary based on
00283   /// Type. This means that the same name can be used for different
00284   /// types without conflict.
00285   /// @brief The mapping of types to names to values.
00286   PlaneMap pmap;
00287 
00288   /// This is the type plane. It is separated from the pmap
00289   /// because the elements of the map are name/Type pairs not
00290   /// name/Value pairs and Type is not a Value.
00291   TypeMap tmap;
00292 
00293   /// This value is used to retain the last unique value used
00294   /// by getUniqueName to generate unique names.
00295   mutable unsigned long LastUnique;
00296 
00297 /// @}
00298 
00299 };
00300 
00301 } // End llvm namespace
00302 
00303 // vim: sw=2
00304 
00305 #endif
00306