Value.h revision bddcb9427cb36ac6609fef233eaac3c9b5e5a8f4
1//===-- llvm/Value.h - Definition of the Value class ------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by the LLVM research group and is distributed under 6// the University of Illinois Open Source License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file declares the Value class. 11// This file also defines the Use<> template for users of value. 12// 13//===----------------------------------------------------------------------===// 14 15#ifndef LLVM_VALUE_H 16#define LLVM_VALUE_H 17 18#include "llvm/AbstractTypeUser.h" 19#include "llvm/Use.h" 20#include "llvm/Support/Casting.h" 21#include <string> 22 23namespace llvm { 24 25class Constant; 26class Argument; 27class Instruction; 28class BasicBlock; 29class GlobalValue; 30class Function; 31class GlobalVariable; 32class InlineAsm; 33class SymbolTable; 34 35//===----------------------------------------------------------------------===// 36// Value Class 37//===----------------------------------------------------------------------===// 38 39/// This is a very important LLVM class. It is the base class of all values 40/// computed by a program that may be used as operands to other values. Value is 41/// the super class of other important classes such as Instruction and Function. 42/// All Values have a Type. Type is not a subclass of Value. All types can have 43/// a name and they should belong to some Module. Setting the name on the Value 44/// automatically update's the module's symbol table. 45/// 46/// Every value has a "use list" that keeps track of which other Values are 47/// using this Value. 48/// @brief LLVM Value Representation 49class Value { 50 unsigned short SubclassID; // Subclass identifier (for isa/dyn_cast) 51protected: 52 /// SubclassData - This member is defined by this class, but is not used for 53 /// anything. Subclasses can use it to hold whatever state they find useful. 54 /// This field is initialized to zero by the ctor. 55 unsigned short SubclassData; 56private: 57 PATypeHolder Ty; 58 Use *UseList; 59 60 friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name. 61 friend class SymbolTable; // Allow SymbolTable to directly poke Name. 62 std::string Name; 63 64 void operator=(const Value &); // Do not implement 65 Value(const Value &); // Do not implement 66 67public: 68 Value(const Type *Ty, unsigned scid, const std::string &name = ""); 69 virtual ~Value(); 70 71 /// dump - Support for debugging, callable in GDB: V->dump() 72 // 73 virtual void dump() const; 74 75 /// print - Implement operator<< on Value... 76 /// 77 virtual void print(std::ostream &O) const = 0; 78 79 /// All values are typed, get the type of this value. 80 /// 81 inline const Type *getType() const { return Ty; } 82 83 // All values can potentially be named... 84 inline bool hasName() const { return !Name.empty(); } 85 inline const std::string &getName() const { return Name; } 86 87 void setName(const std::string &name); 88 89 /// replaceAllUsesWith - Go through the uses list for this definition and make 90 /// each use point to "V" instead of "this". After this completes, 'this's 91 /// use list is guaranteed to be empty. 92 /// 93 void replaceAllUsesWith(Value *V); 94 95 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous. 96 // Only use when in type resolution situations! 97 void uncheckedReplaceAllUsesWith(Value *V); 98 99 //---------------------------------------------------------------------- 100 // Methods for handling the vector of uses of this Value. 101 // 102 typedef value_use_iterator<User> use_iterator; 103 typedef value_use_iterator<const User> use_const_iterator; 104 105 bool use_empty() const { return UseList == 0; } 106 use_iterator use_begin() { return use_iterator(UseList); } 107 use_const_iterator use_begin() const { return use_const_iterator(UseList); } 108 use_iterator use_end() { return use_iterator(0); } 109 use_const_iterator use_end() const { return use_const_iterator(0); } 110 User *use_back() { return *use_begin(); } 111 const User *use_back() const { return *use_begin(); } 112 113 /// hasOneUse - Return true if there is exactly one user of this value. This 114 /// is specialized because it is a common request and does not require 115 /// traversing the whole use list. 116 /// 117 bool hasOneUse() const { 118 use_const_iterator I = use_begin(), E = use_end(); 119 if (I == E) return false; 120 return ++I == E; 121 } 122 123 /// hasNUses - Return true if this Value has exactly N users. 124 /// 125 bool hasNUses(unsigned N) const; 126 127 /// hasNUsesOrMore - Return true if this value has N users or more. This is 128 /// logically equivalent to getNumUses() >= N. 129 /// 130 bool hasNUsesOrMore(unsigned N) const; 131 132 /// getNumUses - This method computes the number of uses of this Value. This 133 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses 134 /// to check for specific values. 135 unsigned getNumUses() const; 136 137 /// addUse/killUse - These two methods should only be used by the Use class. 138 /// 139 void addUse(Use &U) { U.addToList(&UseList); } 140 141 /// An enumeration for keeping track of the concrete subclass of Value that 142 /// is actually instantiated. Values of this enumeration are kept in the 143 /// Value classes SubclassID field. They are used for concrete type 144 /// identification. 145 enum ValueTy { 146 ArgumentVal, // This is an instance of Argument 147 BasicBlockVal, // This is an instance of BasicBlock 148 FunctionVal, // This is an instance of Function 149 GlobalVariableVal, // This is an instance of GlobalVariable 150 UndefValueVal, // This is an instance of UndefValue 151 ConstantExprVal, // This is an instance of ConstantExpr 152 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull 153 ConstantBoolVal, // This is an instance of ConstantBool 154 ConstantSIntVal, // This is an instance of ConstantSInt 155 ConstantUIntVal, // This is an instance of ConstantUInt 156 ConstantFPVal, // This is an instance of ConstantFP 157 ConstantArrayVal, // This is an instance of ConstantArray 158 ConstantStructVal, // This is an instance of ConstantStruct 159 ConstantPackedVal, // This is an instance of ConstantPacked 160 ConstantPointerNullVal, // This is an instance of ConstantPointerNull 161 InlineAsmVal, // This is an instance of InlineAsm 162 InstructionVal, // This is an instance of Instruction 163 164 // Markers: 165 ConstantFirstVal = FunctionVal, 166 ConstantLastVal = ConstantPointerNullVal 167 }; 168 169 /// getValueType - Return an ID for the concrete type of this object. This is 170 /// used to implement the classof checks. This should not be used for any 171 /// other purpose, as the values may change as LLVM evolves. Also, note that 172 /// starting with the InstructionVal value, the value stored is actually the 173 /// Instruction opcode, so there are more than just these values possible here 174 /// (and Instruction must be last). 175 /// 176 unsigned getValueType() const { 177 return SubclassID; 178 } 179 180 // Methods for support type inquiry through isa, cast, and dyn_cast: 181 static inline bool classof(const Value *) { 182 return true; // Values are always values. 183 } 184 185 /// getRawType - This should only be used to implement the vmcore library. 186 /// 187 const Type *getRawType() const { return Ty.getRawType(); } 188 189private: 190 /// FIXME: this is a gross hack, needed by another gross hack. Eliminate! 191 void setValueType(unsigned short VT) { SubclassID = VT; } 192 friend class Instruction; 193}; 194 195inline std::ostream &operator<<(std::ostream &OS, const Value &V) { 196 V.print(OS); 197 return OS; 198} 199 200void Use::init(Value *v, User *user) { 201 Val = v; 202 U = user; 203 if (Val) Val->addUse(*this); 204} 205 206Use::~Use() { 207 if (Val) removeFromList(); 208} 209 210void Use::set(Value *V) { 211 if (Val) removeFromList(); 212 Val = V; 213 if (V) V->addUse(*this); 214} 215 216 217// isa - Provide some specializations of isa so that we don't have to include 218// the subtype header files to test to see if the value is a subclass... 219// 220template <> inline bool isa_impl<Constant, Value>(const Value &Val) { 221 return Val.getValueType() >= Value::ConstantFirstVal && 222 Val.getValueType() <= Value::ConstantLastVal; 223} 224template <> inline bool isa_impl<Argument, Value>(const Value &Val) { 225 return Val.getValueType() == Value::ArgumentVal; 226} 227template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) { 228 return Val.getValueType() == Value::InlineAsmVal; 229} 230template <> inline bool isa_impl<Instruction, Value>(const Value &Val) { 231 return Val.getValueType() >= Value::InstructionVal; 232} 233template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) { 234 return Val.getValueType() == Value::BasicBlockVal; 235} 236template <> inline bool isa_impl<Function, Value>(const Value &Val) { 237 return Val.getValueType() == Value::FunctionVal; 238} 239template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) { 240 return Val.getValueType() == Value::GlobalVariableVal; 241} 242template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) { 243 return isa<GlobalVariable>(Val) || isa<Function>(Val); 244} 245 246} // End llvm namespace 247 248#endif 249