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Value.h

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00001 //===-- llvm/Value.h - Definition of the Value class ------------*- C++ -*-===//
00002 // 
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and is distributed under
00006 // the University of Illinois Open Source License. See LICENSE.TXT for details.
00007 // 
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file defines the very important Value class.  This is subclassed by a
00011 // bunch of other important classes, like Instruction, Function, Type, etc...
00012 //
00013 // This file also defines the Use<> template for users of value.
00014 //
00015 //===----------------------------------------------------------------------===//
00016 
00017 #ifndef LLVM_VALUE_H
00018 #define LLVM_VALUE_H
00019 
00020 #include "llvm/AbstractTypeUser.h"
00021 #include "llvm/Use.h"
00022 #include "llvm/Support/Casting.h"
00023 #include <string>
00024 
00025 namespace llvm {
00026 
00027 class Constant;
00028 class Argument;
00029 class Instruction;
00030 class BasicBlock;
00031 class GlobalValue;
00032 class Function;
00033 class GlobalVariable;
00034 class SymbolTable;
00035 
00036 //===----------------------------------------------------------------------===//
00037 //                                 Value Class
00038 //===----------------------------------------------------------------------===//
00039 
00040 /// Value - The base class of all values computed by a program that may be used
00041 /// as operands to other values.
00042 ///
00043 class Value {
00044 private:
00045   unsigned SubclassID;               // Subclass identifier (for isa/dyn_cast)
00046   PATypeHolder Ty;
00047   iplist<Use> Uses;
00048   std::string Name;
00049 
00050   void operator=(const Value &);     // Do not implement
00051   Value(const Value &);              // Do not implement
00052 
00053 public:
00054   Value(const Type *Ty, unsigned scid, const std::string &name = "");
00055   virtual ~Value();
00056   
00057   /// dump - Support for debugging, callable in GDB: V->dump()
00058   //
00059   virtual void dump() const;
00060 
00061   /// print - Implement operator<< on Value...
00062   ///
00063   virtual void print(std::ostream &O) const = 0;
00064   
00065   /// All values are typed, get the type of this value.
00066   ///
00067   inline const Type *getType() const { return Ty; }
00068   
00069   // All values can potentially be named...
00070   inline bool               hasName() const { return !Name.empty(); }
00071   inline const std::string &getName() const { return Name; }
00072 
00073   virtual void setName(const std::string &name, SymbolTable * = 0) {
00074     Name = name;
00075   }
00076   
00077   /// replaceAllUsesWith - Go through the uses list for this definition and make
00078   /// each use point to "V" instead of "this".  After this completes, 'this's 
00079   /// use list is guaranteed to be empty.
00080   ///
00081   void replaceAllUsesWith(Value *V);
00082 
00083   // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous.
00084   // Only use when in type resolution situations!
00085   void uncheckedReplaceAllUsesWith(Value *V);
00086 
00087   //----------------------------------------------------------------------
00088   // Methods for handling the vector of uses of this Value.
00089   //
00090   typedef UseListIteratorWrapper      use_iterator;
00091   typedef UseListConstIteratorWrapper use_const_iterator;
00092 
00093   unsigned           use_size()  const { return Uses.size();  }
00094   bool               use_empty() const { return Uses.empty(); }
00095   use_iterator       use_begin()       { return Uses.begin(); }
00096   use_const_iterator use_begin() const { return Uses.begin(); }
00097   use_iterator       use_end()         { return Uses.end();   }
00098   use_const_iterator use_end()   const { return Uses.end();   }
00099   User             *use_back()         { return Uses.back().getUser(); }
00100   const User       *use_back()  const  { return Uses.back().getUser(); }
00101 
00102   /// hasOneUse - Return true if there is exactly one user of this value.  This
00103   /// is specialized because it is a common request and does not require
00104   /// traversing the whole use list.
00105   ///
00106   bool hasOneUse() const {
00107     iplist<Use>::const_iterator I = Uses.begin(), E = Uses.end();
00108     if (I == E) return false;
00109     return ++I == E;
00110   }
00111 
00112   /// addUse/killUse - These two methods should only be used by the Use class.
00113   ///
00114   void addUse(Use &U)  { Uses.push_back(&U); }
00115   void killUse(Use &U) { Uses.remove(&U); }
00116 
00117   /// getValueType - Return an ID for the concrete type of this object.  This is
00118   /// used to implement the classof checks.  This should not be used for any
00119   /// other purpose, as the values may change as LLVM evolves.  Also, note that
00120   /// starting with the InstructionVal value, the value stored is actually the
00121   /// Instruction opcode, so there are more than just these values possible here
00122   /// (and Instruction must be last).
00123   ///
00124   enum ValueTy {
00125     ArgumentVal,              // This is an instance of Argument
00126     BasicBlockVal,            // This is an instance of BasicBlock
00127     FunctionVal,              // This is an instance of Function
00128     GlobalVariableVal,        // This is an instance of GlobalVariable
00129     UndefValueVal,            // This is an instance of UndefValue
00130     ConstantExprVal,          // This is an instance of ConstantExpr
00131     ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull
00132     SimpleConstantVal,        // This is some other type of Constant
00133     InstructionVal,           // This is an instance of Instruction
00134     ValueListVal              // This is for bcreader, a special ValTy
00135   };
00136   unsigned getValueType() const {
00137     return SubclassID;
00138   }
00139 
00140   // Methods for support type inquiry through isa, cast, and dyn_cast:
00141   static inline bool classof(const Value *V) {
00142     return true; // Values are always values.
00143   }
00144 
00145   /// getRawType - This should only be used to implement the vmcore library.
00146   ///
00147   const Type *getRawType() const { return Ty.getRawType(); }
00148 
00149 private:
00150   /// FIXME: this is a gross hack, needed by another gross hack.  Eliminate!
00151   void setValueType(unsigned VT) { SubclassID = VT; }
00152   friend class Instruction;
00153 };
00154 
00155 inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
00156   V.print(OS);
00157   return OS;
00158 }
00159 
00160 
00161 inline User *UseListIteratorWrapper::operator*() const {
00162   return Super::operator*().getUser();
00163 }
00164 
00165 inline const User *UseListConstIteratorWrapper::operator*() const {
00166   return Super::operator*().getUser();
00167 }
00168 
00169 
00170 Use::Use(Value *v, User *user) : Val(v), U(user) {
00171   if (Val) Val->addUse(*this);
00172 }
00173 
00174 Use::Use(const Use &u) : Val(u.Val), U(u.U) {
00175   if (Val) Val->addUse(*this);
00176 }
00177 
00178 Use::~Use() {
00179   if (Val) Val->killUse(*this);
00180 }
00181 
00182 void Use::set(Value *V) { 
00183   if (Val) Val->killUse(*this);
00184   Val = V;
00185   if (V) V->addUse(*this);
00186 }
00187 
00188 
00189 // isa - Provide some specializations of isa so that we don't have to include
00190 // the subtype header files to test to see if the value is a subclass...
00191 //
00192 template <> inline bool isa_impl<Constant, Value>(const Value &Val) { 
00193   return Val.getValueType() == Value::SimpleConstantVal ||
00194          Val.getValueType() == Value::FunctionVal ||
00195    Val.getValueType() == Value::GlobalVariableVal ||
00196          Val.getValueType() == Value::ConstantExprVal ||
00197          Val.getValueType() == Value::ConstantAggregateZeroVal ||
00198          Val.getValueType() == Value::UndefValueVal;
00199 }
00200 template <> inline bool isa_impl<Argument, Value>(const Value &Val) { 
00201   return Val.getValueType() == Value::ArgumentVal;
00202 }
00203 template <> inline bool isa_impl<Instruction, Value>(const Value &Val) { 
00204   return Val.getValueType() >= Value::InstructionVal;
00205 }
00206 template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) { 
00207   return Val.getValueType() == Value::BasicBlockVal;
00208 }
00209 template <> inline bool isa_impl<Function, Value>(const Value &Val) { 
00210   return Val.getValueType() == Value::FunctionVal;
00211 }
00212 template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) { 
00213   return Val.getValueType() == Value::GlobalVariableVal;
00214 }
00215 template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) { 
00216   return isa<GlobalVariable>(Val) || isa<Function>(Val);
00217 }
00218 
00219 } // End llvm namespace
00220 
00221 #endif