Value.h revision 6c6c016b1b9711bc8968b51746d4b867e17905f4
1//===-- llvm/Value.h - Definition of the Value class ------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file declares the Value class. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_VALUE_H 15#define LLVM_VALUE_H 16 17#include "llvm/AbstractTypeUser.h" 18#include "llvm/Use.h" 19#include "llvm/ADT/StringRef.h" 20#include "llvm/ADT/Twine.h" 21#include "llvm/Support/Casting.h" 22#include <string> 23 24namespace llvm { 25 26class Constant; 27class Argument; 28class Instruction; 29class BasicBlock; 30class GlobalValue; 31class Function; 32class GlobalVariable; 33class GlobalAlias; 34class InlineAsm; 35class ValueSymbolTable; 36class TypeSymbolTable; 37template<typename ValueTy> class StringMapEntry; 38template <typename ValueTy = Value> 39class AssertingVH; 40typedef StringMapEntry<Value*> ValueName; 41class raw_ostream; 42class AssemblyAnnotationWriter; 43class ValueHandleBase; 44class LLVMContext; 45class Metadata; 46 47//===----------------------------------------------------------------------===// 48// Value Class 49//===----------------------------------------------------------------------===// 50 51/// This is a very important LLVM class. It is the base class of all values 52/// computed by a program that may be used as operands to other values. Value is 53/// the super class of other important classes such as Instruction and Function. 54/// All Values have a Type. Type is not a subclass of Value. All types can have 55/// a name and they should belong to some Module. Setting the name on the Value 56/// automatically updates the module's symbol table. 57/// 58/// Every value has a "use list" that keeps track of which other Values are 59/// using this Value. A Value can also have an arbitrary number of ValueHandle 60/// objects that watch it and listen to RAUW and Destroy events see 61/// llvm/Support/ValueHandle.h for details. 62/// 63/// @brief LLVM Value Representation 64class Value { 65 const unsigned char SubclassID; // Subclass identifier (for isa/dyn_cast) 66 unsigned char HasValueHandle : 1; // Has a ValueHandle pointing to this? 67 unsigned char HasMetadata : 1; // Has a metadata attached to this ? 68protected: 69 /// SubclassOptionalData - This member is similar to SubclassData, however it 70 /// is for holding information which may be used to aid optimization, but 71 /// which may be cleared to zero without affecting conservative 72 /// interpretation. 73 unsigned char SubclassOptionalData : 7; 74 75 /// SubclassData - This member is defined by this class, but is not used for 76 /// anything. Subclasses can use it to hold whatever state they find useful. 77 /// This field is initialized to zero by the ctor. 78 unsigned short SubclassData; 79private: 80 PATypeHolder VTy; 81 Use *UseList; 82 83 friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name. 84 friend class SymbolTable; // Allow SymbolTable to directly poke Name. 85 friend class ValueHandleBase; 86 friend class Metadata; 87 friend class AbstractTypeUser; 88 ValueName *Name; 89 90 void operator=(const Value &); // Do not implement 91 Value(const Value &); // Do not implement 92 93protected: 94 /// printCustom - Value subclasses can override this to implement custom 95 /// printing behavior. 96 virtual void printCustom(raw_ostream &O) const; 97 98public: 99 Value(const Type *Ty, unsigned scid); 100 virtual ~Value(); 101 102 /// dump - Support for debugging, callable in GDB: V->dump() 103 // 104 void dump() const; 105 106 /// print - Implement operator<< on Value. 107 /// 108 void print(raw_ostream &O, AssemblyAnnotationWriter *AAW = 0) const; 109 110 /// All values are typed, get the type of this value. 111 /// 112 inline const Type *getType() const { return VTy; } 113 114 /// All values hold a context through their type. 115 LLVMContext &getContext() const; 116 117 // All values can potentially be named... 118 inline bool hasName() const { return Name != 0; } 119 ValueName *getValueName() const { return Name; } 120 121 /// getName() - Return a constant reference to the value's name. This is cheap 122 /// and guaranteed to return the same reference as long as the value is not 123 /// modified. 124 /// 125 /// This is currently guaranteed to return a StringRef for which data() points 126 /// to a valid null terminated string. The use of StringRef.data() is 127 /// deprecated here, however, and clients should not rely on it. If such 128 /// behavior is needed, clients should use expensive getNameStr(), or switch 129 /// to an interface that does not depend on null termination. 130 StringRef getName() const; 131 132 /// getNameStr() - Return the name of the specified value, *constructing a 133 /// string* to hold it. This is guaranteed to construct a string and is very 134 /// expensive, clients should use getName() unless necessary. 135 std::string getNameStr() const; 136 137 /// setName() - Change the name of the value, choosing a new unique name if 138 /// the provided name is taken. 139 /// 140 /// \arg Name - The new name; or "" if the value's name should be removed. 141 void setName(const Twine &Name); 142 143 144 /// takeName - transfer the name from V to this value, setting V's name to 145 /// empty. It is an error to call V->takeName(V). 146 void takeName(Value *V); 147 148 /// replaceAllUsesWith - Go through the uses list for this definition and make 149 /// each use point to "V" instead of "this". After this completes, 'this's 150 /// use list is guaranteed to be empty. 151 /// 152 void replaceAllUsesWith(Value *V); 153 154 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous. 155 // Only use when in type resolution situations! 156 void uncheckedReplaceAllUsesWith(Value *V); 157 158 //---------------------------------------------------------------------- 159 // Methods for handling the chain of uses of this Value. 160 // 161 typedef value_use_iterator<User> use_iterator; 162 typedef value_use_iterator<const User> use_const_iterator; 163 164 bool use_empty() const { return UseList == 0; } 165 use_iterator use_begin() { return use_iterator(UseList); } 166 use_const_iterator use_begin() const { return use_const_iterator(UseList); } 167 use_iterator use_end() { return use_iterator(0); } 168 use_const_iterator use_end() const { return use_const_iterator(0); } 169 User *use_back() { return *use_begin(); } 170 const User *use_back() const { return *use_begin(); } 171 172 /// hasOneUse - Return true if there is exactly one user of this value. This 173 /// is specialized because it is a common request and does not require 174 /// traversing the whole use list. 175 /// 176 bool hasOneUse() const { 177 use_const_iterator I = use_begin(), E = use_end(); 178 if (I == E) return false; 179 return ++I == E; 180 } 181 182 /// hasNUses - Return true if this Value has exactly N users. 183 /// 184 bool hasNUses(unsigned N) const; 185 186 /// hasNUsesOrMore - Return true if this value has N users or more. This is 187 /// logically equivalent to getNumUses() >= N. 188 /// 189 bool hasNUsesOrMore(unsigned N) const; 190 191 bool isUsedInBasicBlock(const BasicBlock *BB) const; 192 193 /// getNumUses - This method computes the number of uses of this Value. This 194 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses 195 /// to check for specific values. 196 unsigned getNumUses() const; 197 198 /// addUse - This method should only be used by the Use class. 199 /// 200 void addUse(Use &U) { U.addToList(&UseList); } 201 202 /// An enumeration for keeping track of the concrete subclass of Value that 203 /// is actually instantiated. Values of this enumeration are kept in the 204 /// Value classes SubclassID field. They are used for concrete type 205 /// identification. 206 enum ValueTy { 207 ArgumentVal, // This is an instance of Argument 208 BasicBlockVal, // This is an instance of BasicBlock 209 FunctionVal, // This is an instance of Function 210 GlobalAliasVal, // This is an instance of GlobalAlias 211 GlobalVariableVal, // This is an instance of GlobalVariable 212 UndefValueVal, // This is an instance of UndefValue 213 ConstantExprVal, // This is an instance of ConstantExpr 214 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull 215 ConstantIntVal, // This is an instance of ConstantInt 216 ConstantFPVal, // This is an instance of ConstantFP 217 ConstantArrayVal, // This is an instance of ConstantArray 218 ConstantStructVal, // This is an instance of ConstantStruct 219 ConstantVectorVal, // This is an instance of ConstantVector 220 ConstantPointerNullVal, // This is an instance of ConstantPointerNull 221 MDNodeVal, // This is an instance of MDNode 222 MDStringVal, // This is an instance of MDString 223 NamedMDNodeVal, // This is an instance of NamedMDNode 224 InlineAsmVal, // This is an instance of InlineAsm 225 PseudoSourceValueVal, // This is an instance of PseudoSourceValue 226 InstructionVal, // This is an instance of Instruction 227 228 // Markers: 229 ConstantFirstVal = FunctionVal, 230 ConstantLastVal = ConstantPointerNullVal 231 }; 232 233 /// getValueID - Return an ID for the concrete type of this object. This is 234 /// used to implement the classof checks. This should not be used for any 235 /// other purpose, as the values may change as LLVM evolves. Also, note that 236 /// for instructions, the Instruction's opcode is added to InstructionVal. So 237 /// this means three things: 238 /// # there is no value with code InstructionVal (no opcode==0). 239 /// # there are more possible values for the value type than in ValueTy enum. 240 /// # the InstructionVal enumerator must be the highest valued enumerator in 241 /// the ValueTy enum. 242 unsigned getValueID() const { 243 return SubclassID; 244 } 245 246 /// getRawSubclassOptionalData - Return the raw optional flags value 247 /// contained in this value. This should only be used when testing two 248 /// Values for equivalence. 249 unsigned getRawSubclassOptionalData() const { 250 return SubclassOptionalData; 251 } 252 253 /// hasSameSubclassOptionalData - Test whether the optional flags contained 254 /// in this value are equal to the optional flags in the given value. 255 bool hasSameSubclassOptionalData(const Value *V) const { 256 return SubclassOptionalData == V->SubclassOptionalData; 257 } 258 259 /// intersectOptionalDataWith - Clear any optional flags in this value 260 /// that are not also set in the given value. 261 void intersectOptionalDataWith(const Value *V) { 262 SubclassOptionalData &= V->SubclassOptionalData; 263 } 264 265 // Methods for support type inquiry through isa, cast, and dyn_cast: 266 static inline bool classof(const Value *) { 267 return true; // Values are always values. 268 } 269 270 /// getRawType - This should only be used to implement the vmcore library. 271 /// 272 const Type *getRawType() const { return VTy.getRawType(); } 273 274 /// stripPointerCasts - This method strips off any unneeded pointer 275 /// casts from the specified value, returning the original uncasted value. 276 /// Note that the returned value has pointer type if the specified value does. 277 Value *stripPointerCasts(); 278 const Value *stripPointerCasts() const { 279 return const_cast<Value*>(this)->stripPointerCasts(); 280 } 281 282 /// getUnderlyingObject - This method strips off any GEP address adjustments 283 /// and pointer casts from the specified value, returning the original object 284 /// being addressed. Note that the returned value has pointer type if the 285 /// specified value does. 286 Value *getUnderlyingObject(); 287 const Value *getUnderlyingObject() const { 288 return const_cast<Value*>(this)->getUnderlyingObject(); 289 } 290 291 /// DoPHITranslation - If this value is a PHI node with CurBB as its parent, 292 /// return the value in the PHI node corresponding to PredBB. If not, return 293 /// ourself. This is useful if you want to know the value something has in a 294 /// predecessor block. 295 Value *DoPHITranslation(const BasicBlock *CurBB, const BasicBlock *PredBB); 296 297 const Value *DoPHITranslation(const BasicBlock *CurBB, 298 const BasicBlock *PredBB) const{ 299 return const_cast<Value*>(this)->DoPHITranslation(CurBB, PredBB); 300 } 301 302 /// hasMetadata - Return true if metadata is attached with this value. 303 bool hasMetadata() const { return HasMetadata; } 304}; 305 306inline raw_ostream &operator<<(raw_ostream &OS, const Value &V) { 307 V.print(OS); 308 return OS; 309} 310 311void Use::set(Value *V) { 312 if (Val) removeFromList(); 313 Val = V; 314 if (V) V->addUse(*this); 315} 316 317 318// isa - Provide some specializations of isa so that we don't have to include 319// the subtype header files to test to see if the value is a subclass... 320// 321template <> inline bool isa_impl<Constant, Value>(const Value &Val) { 322 return Val.getValueID() >= Value::ConstantFirstVal && 323 Val.getValueID() <= Value::ConstantLastVal; 324} 325template <> inline bool isa_impl<Argument, Value>(const Value &Val) { 326 return Val.getValueID() == Value::ArgumentVal; 327} 328template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) { 329 return Val.getValueID() == Value::InlineAsmVal; 330} 331template <> inline bool isa_impl<Instruction, Value>(const Value &Val) { 332 return Val.getValueID() >= Value::InstructionVal; 333} 334template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) { 335 return Val.getValueID() == Value::BasicBlockVal; 336} 337template <> inline bool isa_impl<Function, Value>(const Value &Val) { 338 return Val.getValueID() == Value::FunctionVal; 339} 340template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) { 341 return Val.getValueID() == Value::GlobalVariableVal; 342} 343template <> inline bool isa_impl<GlobalAlias, Value>(const Value &Val) { 344 return Val.getValueID() == Value::GlobalAliasVal; 345} 346template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) { 347 return isa<GlobalVariable>(Val) || isa<Function>(Val) || 348 isa<GlobalAlias>(Val); 349} 350 351 352// Value* is only 4-byte aligned. 353template<> 354class PointerLikeTypeTraits<Value*> { 355 typedef Value* PT; 356public: 357 static inline void *getAsVoidPointer(PT P) { return P; } 358 static inline PT getFromVoidPointer(void *P) { 359 return static_cast<PT>(P); 360 } 361 enum { NumLowBitsAvailable = 2 }; 362}; 363 364} // End llvm namespace 365 366#endif 367