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Constant.h

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00001 //===-- llvm/Constant.h - Constant class definition -------------*- 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 contains the declaration of the Constant class.
00011 //
00012 //===----------------------------------------------------------------------===//
00013 
00014 #ifndef LLVM_CONSTANT_H
00015 #define LLVM_CONSTANT_H
00016 
00017 #include "llvm/User.h"
00018 
00019 namespace llvm {
00020 
00021 class Constant : public User {
00022 protected:
00023   inline Constant(const Type *Ty, ValueTy vty = Value::SimpleConstantVal, 
00024                   const std::string& Name = "")
00025   : User(Ty, vty, Name) {}
00026   ~Constant() {}
00027 
00028   void destroyConstantImpl();
00029 public:
00030   // setName - Specialize setName to handle symbol table majik...
00031   virtual void setName(const std::string &name, SymbolTable *ST = 0);
00032 
00033   /// Static constructor to get a '0' constant of arbitrary type...
00034   ///
00035   static Constant *getNullValue(const Type *Ty);
00036 
00037   /// isNullValue - Return true if this is the value that would be returned by
00038   /// getNullValue.
00039   virtual bool isNullValue() const = 0;
00040 
00041   virtual void print(std::ostream &O) const;
00042 
00043   // Specialize get/setOperand for Constant's as their operands are always
00044   // constants as well.
00045   Constant *getOperand(unsigned i) { 
00046     return static_cast<Constant*>(User::getOperand(i));
00047   }
00048   const Constant *getOperand(unsigned i) const {
00049     return static_cast<const Constant*>(User::getOperand(i));
00050   }
00051   void setOperand(unsigned i, Constant *C) {
00052     User::setOperand(i, C);
00053   }
00054 
00055   /// destroyConstant - Called if some element of this constant is no longer
00056   /// valid.  At this point only other constants may be on the use_list for this
00057   /// constant.  Any constants on our Use list must also be destroy'd.  The
00058   /// implementation must be sure to remove the constant from the list of
00059   /// available cached constants.  Implementations should call
00060   /// destroyConstantImpl as the last thing they do, to destroy all users and
00061   /// delete this.
00062   virtual void destroyConstant() { assert(0 && "Not reached!"); }
00063   
00064   //// Methods for support type inquiry through isa, cast, and dyn_cast:
00065   static inline bool classof(const Constant *) { return true; }
00066   static inline bool classof(const GlobalValue *) { return true; }
00067   static inline bool classof(const Value *V) {
00068     return V->getValueType() == Value::SimpleConstantVal ||
00069            V->getValueType() == Value::ConstantExprVal ||
00070            V->getValueType() == Value::ConstantAggregateZeroVal ||
00071            V->getValueType() == Value::FunctionVal ||
00072            V->getValueType() == Value::GlobalVariableVal ||
00073            V->getValueType() == Value::UndefValueVal;
00074   }
00075 
00076   /// replaceUsesOfWithOnConstant - This method is a special form of
00077   /// User::replaceUsesOfWith (which does not work on constants) that does work
00078   /// on constants.  Basically this method goes through the trouble of building
00079   /// a new constant that is equivalent to the current one, with all uses of
00080   /// From replaced with uses of To.  After this construction is completed, all
00081   /// of the users of 'this' are replaced to use the new constant, and then
00082   /// 'this' is deleted.  In general, you should not call this method, instead,
00083   /// use Value::replaceAllUsesWith, which automatically dispatches to this
00084   /// method as needed.
00085   ///
00086   virtual void replaceUsesOfWithOnConstant(Value *From, Value *To,
00087                                            bool DisableChecking = false) {
00088     // Provide a default implementation for constants (like integers) that
00089     // cannot use any other values.  This cannot be called at runtime, but needs
00090     // to be here to avoid link errors.
00091     assert(getNumOperands() == 0 && "replaceUsesOfWithOnConstant must be "
00092            "implemented for all constants that have operands!");
00093     assert(0 && "Constants that do not have operands cannot be using 'From'!");
00094   }
00095 
00096   /// clearAllValueMaps - This method frees all internal memory used by the
00097   /// constant subsystem, which can be used in environments where this memory
00098   /// is otherwise reported as a leak.
00099   static void clearAllValueMaps();
00100 };
00101 
00102 } // End llvm namespace
00103 
00104 #endif