LLVM API Documentation
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 declares the Value class. 00011 // This file also defines the Use<> template for users of value. 00012 // 00013 //===----------------------------------------------------------------------===// 00014 00015 #ifndef LLVM_VALUE_H 00016 #define LLVM_VALUE_H 00017 00018 #include "llvm/AbstractTypeUser.h" 00019 #include "llvm/Use.h" 00020 #include "llvm/Support/Casting.h" 00021 #include <string> 00022 00023 namespace llvm { 00024 00025 class Constant; 00026 class Argument; 00027 class Instruction; 00028 class BasicBlock; 00029 class GlobalValue; 00030 class Function; 00031 class GlobalVariable; 00032 class InlineAsm; 00033 class SymbolTable; 00034 00035 //===----------------------------------------------------------------------===// 00036 // Value Class 00037 //===----------------------------------------------------------------------===// 00038 00039 /// This is a very important LLVM class. It is the base class of all values 00040 /// computed by a program that may be used as operands to other values. Value is 00041 /// the super class of other important classes such as Instruction and Function. 00042 /// All Values have a Type. Type is not a subclass of Value. All types can have 00043 /// a name and they should belong to some Module. Setting the name on the Value 00044 /// automatically update's the module's symbol table. 00045 /// 00046 /// Every value has a "use list" that keeps track of which other Values are 00047 /// using this Value. 00048 /// @brief LLVM Value Representation 00049 class Value { 00050 unsigned short SubclassID; // Subclass identifier (for isa/dyn_cast) 00051 protected: 00052 /// SubclassData - This member is defined by this class, but is not used for 00053 /// anything. Subclasses can use it to hold whatever state they find useful. 00054 /// This field is initialized to zero by the ctor. 00055 unsigned short SubclassData; 00056 private: 00057 PATypeHolder Ty; 00058 Use *UseList; 00059 00060 friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name. 00061 friend class SymbolTable; // Allow SymbolTable to directly poke Name. 00062 std::string Name; 00063 00064 void operator=(const Value &); // Do not implement 00065 Value(const Value &); // Do not implement 00066 00067 public: 00068 Value(const Type *Ty, unsigned scid, const std::string &name = ""); 00069 virtual ~Value(); 00070 00071 /// dump - Support for debugging, callable in GDB: V->dump() 00072 // 00073 virtual void dump() const; 00074 00075 /// print - Implement operator<< on Value... 00076 /// 00077 virtual void print(std::ostream &O) const = 0; 00078 00079 /// All values are typed, get the type of this value. 00080 /// 00081 inline const Type *getType() const { return Ty; } 00082 00083 // All values can potentially be named... 00084 inline bool hasName() const { return !Name.empty(); } 00085 inline const std::string &getName() const { return Name; } 00086 00087 void setName(const std::string &name); 00088 00089 /// replaceAllUsesWith - Go through the uses list for this definition and make 00090 /// each use point to "V" instead of "this". After this completes, 'this's 00091 /// use list is guaranteed to be empty. 00092 /// 00093 void replaceAllUsesWith(Value *V); 00094 00095 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous. 00096 // Only use when in type resolution situations! 00097 void uncheckedReplaceAllUsesWith(Value *V); 00098 00099 //---------------------------------------------------------------------- 00100 // Methods for handling the vector of uses of this Value. 00101 // 00102 typedef value_use_iterator<User> use_iterator; 00103 typedef value_use_iterator<const User> use_const_iterator; 00104 00105 bool use_empty() const { return UseList == 0; } 00106 use_iterator use_begin() { return use_iterator(UseList); } 00107 use_const_iterator use_begin() const { return use_const_iterator(UseList); } 00108 use_iterator use_end() { return use_iterator(0); } 00109 use_const_iterator use_end() const { return use_const_iterator(0); } 00110 User *use_back() { return *use_begin(); } 00111 const User *use_back() const { return *use_begin(); } 00112 00113 /// hasOneUse - Return true if there is exactly one user of this value. This 00114 /// is specialized because it is a common request and does not require 00115 /// traversing the whole use list. 00116 /// 00117 bool hasOneUse() const { 00118 use_const_iterator I = use_begin(), E = use_end(); 00119 if (I == E) return false; 00120 return ++I == E; 00121 } 00122 00123 /// hasNUses - Return true if this Value has exactly N users. 00124 /// 00125 bool hasNUses(unsigned N) const; 00126 00127 /// hasNUsesOrMore - Return true if this value has N users or more. This is 00128 /// logically equivalent to getNumUses() >= N. 00129 /// 00130 bool hasNUsesOrMore(unsigned N) const; 00131 00132 /// getNumUses - This method computes the number of uses of this Value. This 00133 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses 00134 /// to check for specific values. 00135 unsigned getNumUses() const; 00136 00137 /// addUse/killUse - These two methods should only be used by the Use class. 00138 /// 00139 void addUse(Use &U) { U.addToList(&UseList); } 00140 00141 /// An enumeration for keeping track of the concrete subclass of Value that 00142 /// is actually instantiated. Values of this enumeration are kept in the 00143 /// Value classes SubclassID field. They are used for concrete type 00144 /// identification. 00145 enum ValueTy { 00146 ArgumentVal, // This is an instance of Argument 00147 BasicBlockVal, // This is an instance of BasicBlock 00148 FunctionVal, // This is an instance of Function 00149 GlobalVariableVal, // This is an instance of GlobalVariable 00150 UndefValueVal, // This is an instance of UndefValue 00151 ConstantExprVal, // This is an instance of ConstantExpr 00152 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull 00153 ConstantBoolVal, // This is an instance of ConstantBool 00154 ConstantSIntVal, // This is an instance of ConstantSInt 00155 ConstantUIntVal, // This is an instance of ConstantUInt 00156 ConstantFPVal, // This is an instance of ConstantFP 00157 ConstantArrayVal, // This is an instance of ConstantArray 00158 ConstantStructVal, // This is an instance of ConstantStruct 00159 ConstantPackedVal, // This is an instance of ConstantPacked 00160 ConstantPointerNullVal, // This is an instance of ConstantPointerNull 00161 InlineAsmVal, // This is an instance of InlineAsm 00162 InstructionVal, // This is an instance of Instruction 00163 00164 // Markers: 00165 ConstantFirstVal = FunctionVal, 00166 ConstantLastVal = ConstantPointerNullVal 00167 }; 00168 00169 /// getValueType - Return an ID for the concrete type of this object. This is 00170 /// used to implement the classof checks. This should not be used for any 00171 /// other purpose, as the values may change as LLVM evolves. Also, note that 00172 /// starting with the InstructionVal value, the value stored is actually the 00173 /// Instruction opcode, so there are more than just these values possible here 00174 /// (and Instruction must be last). 00175 /// 00176 unsigned getValueType() const { 00177 return SubclassID; 00178 } 00179 00180 // Methods for support type inquiry through isa, cast, and dyn_cast: 00181 static inline bool classof(const Value *) { 00182 return true; // Values are always values. 00183 } 00184 00185 /// getRawType - This should only be used to implement the vmcore library. 00186 /// 00187 const Type *getRawType() const { return Ty.getRawType(); } 00188 00189 private: 00190 /// FIXME: this is a gross hack, needed by another gross hack. Eliminate! 00191 void setValueType(unsigned short VT) { SubclassID = VT; } 00192 friend class Instruction; 00193 }; 00194 00195 inline std::ostream &operator<<(std::ostream &OS, const Value &V) { 00196 V.print(OS); 00197 return OS; 00198 } 00199 00200 void Use::init(Value *v, User *user) { 00201 Val = v; 00202 U = user; 00203 if (Val) Val->addUse(*this); 00204 } 00205 00206 Use::~Use() { 00207 if (Val) removeFromList(); 00208 } 00209 00210 void Use::set(Value *V) { 00211 if (Val) removeFromList(); 00212 Val = V; 00213 if (V) V->addUse(*this); 00214 } 00215 00216 00217 // isa - Provide some specializations of isa so that we don't have to include 00218 // the subtype header files to test to see if the value is a subclass... 00219 // 00220 template <> inline bool isa_impl<Constant, Value>(const Value &Val) { 00221 return Val.getValueType() >= Value::ConstantFirstVal && 00222 Val.getValueType() <= Value::ConstantLastVal; 00223 } 00224 template <> inline bool isa_impl<Argument, Value>(const Value &Val) { 00225 return Val.getValueType() == Value::ArgumentVal; 00226 } 00227 template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) { 00228 return Val.getValueType() == Value::InlineAsmVal; 00229 } 00230 template <> inline bool isa_impl<Instruction, Value>(const Value &Val) { 00231 return Val.getValueType() >= Value::InstructionVal; 00232 } 00233 template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) { 00234 return Val.getValueType() == Value::BasicBlockVal; 00235 } 00236 template <> inline bool isa_impl<Function, Value>(const Value &Val) { 00237 return Val.getValueType() == Value::FunctionVal; 00238 } 00239 template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) { 00240 return Val.getValueType() == Value::GlobalVariableVal; 00241 } 00242 template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) { 00243 return isa<GlobalVariable>(Val) || isa<Function>(Val); 00244 } 00245 00246 } // End llvm namespace 00247 00248 #endif