Value.h revision 5034dd318a9dfa0dc45a3ac01e58e60f2aa2498d
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/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 GlobalAlias; 33class InlineAsm; 34class ValueSymbolTable; 35class TypeSymbolTable; 36template<typename ValueTy> class StringMapEntry; 37template <typename ValueTy = Value> 38class AssertingVH; 39typedef StringMapEntry<Value*> ValueName; 40class raw_ostream; 41class AssemblyAnnotationWriter; 42class ValueHandleBase; 43class LLVMContext; 44class Twine; 45class MDNode; 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? 67protected: 68 /// SubclassOptionalData - This member is similar to SubclassData, however it 69 /// is for holding information which may be used to aid optimization, but 70 /// which may be cleared to zero without affecting conservative 71 /// interpretation. 72 unsigned char SubclassOptionalData : 7; 73 74private: 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; 79 80 PATypeHolder VTy; 81 Use *UseList; 82 83 friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name. 84 friend class ValueHandleBase; 85 friend class AbstractTypeUser; 86 ValueName *Name; 87 88 void operator=(const Value &); // Do not implement 89 Value(const Value &); // Do not implement 90 91protected: 92 /// printCustom - Value subclasses can override this to implement custom 93 /// printing behavior. 94 virtual void printCustom(raw_ostream &O) const; 95 96 Value(const Type *Ty, unsigned scid); 97public: 98 virtual ~Value(); 99 100 /// dump - Support for debugging, callable in GDB: V->dump() 101 // 102 void dump() const; 103 104 /// print - Implement operator<< on Value. 105 /// 106 void print(raw_ostream &O, AssemblyAnnotationWriter *AAW = 0) const; 107 108 /// All values are typed, get the type of this value. 109 /// 110 inline const Type *getType() const { return VTy; } 111 112 /// All values hold a context through their type. 113 LLVMContext &getContext() const; 114 115 // All values can potentially be named... 116 inline bool hasName() const { return Name != 0; } 117 ValueName *getValueName() const { return Name; } 118 119 /// getName() - Return a constant reference to the value's name. This is cheap 120 /// and guaranteed to return the same reference as long as the value is not 121 /// modified. 122 /// 123 /// This is currently guaranteed to return a StringRef for which data() points 124 /// to a valid null terminated string. The use of StringRef.data() is 125 /// deprecated here, however, and clients should not rely on it. If such 126 /// behavior is needed, clients should use expensive getNameStr(), or switch 127 /// to an interface that does not depend on null termination. 128 StringRef getName() const; 129 130 /// getNameStr() - Return the name of the specified value, *constructing a 131 /// string* to hold it. This is guaranteed to construct a string and is very 132 /// expensive, clients should use getName() unless necessary. 133 std::string getNameStr() const; 134 135 /// setName() - Change the name of the value, choosing a new unique name if 136 /// the provided name is taken. 137 /// 138 /// \arg Name - The new name; or "" if the value's name should be removed. 139 void setName(const Twine &Name); 140 141 142 /// takeName - transfer the name from V to this value, setting V's name to 143 /// empty. It is an error to call V->takeName(V). 144 void takeName(Value *V); 145 146 /// replaceAllUsesWith - Go through the uses list for this definition and make 147 /// each use point to "V" instead of "this". After this completes, 'this's 148 /// use list is guaranteed to be empty. 149 /// 150 void replaceAllUsesWith(Value *V); 151 152 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous. 153 // Only use when in type resolution situations! 154 void uncheckedReplaceAllUsesWith(Value *V); 155 156 //---------------------------------------------------------------------- 157 // Methods for handling the chain of uses of this Value. 158 // 159 typedef value_use_iterator<User> use_iterator; 160 typedef value_use_iterator<const User> const_use_iterator; 161 162 bool use_empty() const { return UseList == 0; } 163 use_iterator use_begin() { return use_iterator(UseList); } 164 const_use_iterator use_begin() const { return const_use_iterator(UseList); } 165 use_iterator use_end() { return use_iterator(0); } 166 const_use_iterator use_end() const { return const_use_iterator(0); } 167 User *use_back() { return *use_begin(); } 168 const User *use_back() const { return *use_begin(); } 169 170 /// hasOneUse - Return true if there is exactly one user of this value. This 171 /// is specialized because it is a common request and does not require 172 /// traversing the whole use list. 173 /// 174 bool hasOneUse() const { 175 const_use_iterator I = use_begin(), E = use_end(); 176 if (I == E) return false; 177 return ++I == E; 178 } 179 180 /// hasNUses - Return true if this Value has exactly N users. 181 /// 182 bool hasNUses(unsigned N) const; 183 184 /// hasNUsesOrMore - Return true if this value has N users or more. This is 185 /// logically equivalent to getNumUses() >= N. 186 /// 187 bool hasNUsesOrMore(unsigned N) const; 188 189 bool isUsedInBasicBlock(const BasicBlock *BB) const; 190 191 /// getNumUses - This method computes the number of uses of this Value. This 192 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses 193 /// to check for specific values. 194 unsigned getNumUses() const; 195 196 /// addUse - This method should only be used by the Use class. 197 /// 198 void addUse(Use &U) { U.addToList(&UseList); } 199 200 /// An enumeration for keeping track of the concrete subclass of Value that 201 /// is actually instantiated. Values of this enumeration are kept in the 202 /// Value classes SubclassID field. They are used for concrete type 203 /// identification. 204 enum ValueTy { 205 ArgumentVal, // This is an instance of Argument 206 BasicBlockVal, // This is an instance of BasicBlock 207 FunctionVal, // This is an instance of Function 208 GlobalAliasVal, // This is an instance of GlobalAlias 209 GlobalVariableVal, // This is an instance of GlobalVariable 210 UndefValueVal, // This is an instance of UndefValue 211 BlockAddressVal, // This is an instance of BlockAddress 212 ConstantExprVal, // This is an instance of ConstantExpr 213 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateZero 214 ConstantIntVal, // This is an instance of ConstantInt 215 ConstantFPVal, // This is an instance of ConstantFP 216 ConstantArrayVal, // This is an instance of ConstantArray 217 ConstantStructVal, // This is an instance of ConstantStruct 218 ConstantVectorVal, // This is an instance of ConstantVector 219 ConstantPointerNullVal, // This is an instance of ConstantPointerNull 220 MDNodeVal, // This is an instance of MDNode 221 MDStringVal, // This is an instance of MDString 222 InlineAsmVal, // This is an instance of InlineAsm 223 PseudoSourceValueVal, // This is an instance of PseudoSourceValue 224 FixedStackPseudoSourceValueVal, // This is an instance of 225 // FixedStackPseudoSourceValue 226 InstructionVal, // This is an instance of Instruction 227 // Enum values starting at InstructionVal are used for Instructions; 228 // don't add new values here! 229 230 // Markers: 231 ConstantFirstVal = FunctionVal, 232 ConstantLastVal = ConstantPointerNullVal 233 }; 234 235 /// getValueID - Return an ID for the concrete type of this object. This is 236 /// used to implement the classof checks. This should not be used for any 237 /// other purpose, as the values may change as LLVM evolves. Also, note that 238 /// for instructions, the Instruction's opcode is added to InstructionVal. So 239 /// this means three things: 240 /// # there is no value with code InstructionVal (no opcode==0). 241 /// # there are more possible values for the value type than in ValueTy enum. 242 /// # the InstructionVal enumerator must be the highest valued enumerator in 243 /// the ValueTy enum. 244 unsigned getValueID() const { 245 return SubclassID; 246 } 247 248 /// getRawSubclassOptionalData - Return the raw optional flags value 249 /// contained in this value. This should only be used when testing two 250 /// Values for equivalence. 251 unsigned getRawSubclassOptionalData() const { 252 return SubclassOptionalData; 253 } 254 255 /// hasSameSubclassOptionalData - Test whether the optional flags contained 256 /// in this value are equal to the optional flags in the given value. 257 bool hasSameSubclassOptionalData(const Value *V) const { 258 return SubclassOptionalData == V->SubclassOptionalData; 259 } 260 261 /// intersectOptionalDataWith - Clear any optional flags in this value 262 /// that are not also set in the given value. 263 void intersectOptionalDataWith(const Value *V) { 264 SubclassOptionalData &= V->SubclassOptionalData; 265 } 266 267 /// hasValueHandle - Return true if there is a value handle associated with 268 /// this value. 269 bool hasValueHandle() const { return HasValueHandle; } 270 271 // Methods for support type inquiry through isa, cast, and dyn_cast: 272 static inline bool classof(const Value *) { 273 return true; // Values are always values. 274 } 275 276 /// getRawType - This should only be used to implement the vmcore library. 277 /// 278 const Type *getRawType() const { return VTy.getRawType(); } 279 280 /// stripPointerCasts - This method strips off any unneeded pointer 281 /// casts from the specified value, returning the original uncasted value. 282 /// Note that the returned value has pointer type if the specified value does. 283 Value *stripPointerCasts(); 284 const Value *stripPointerCasts() const { 285 return const_cast<Value*>(this)->stripPointerCasts(); 286 } 287 288 /// isDereferenceablePointer - Test if this value is always a pointer to 289 /// allocated and suitably aligned memory for a simple load or store. 290 bool isDereferenceablePointer() const; 291 292 /// DoPHITranslation - If this value is a PHI node with CurBB as its parent, 293 /// return the value in the PHI node corresponding to PredBB. If not, return 294 /// ourself. This is useful if you want to know the value something has in a 295 /// predecessor block. 296 Value *DoPHITranslation(const BasicBlock *CurBB, const BasicBlock *PredBB); 297 298 const Value *DoPHITranslation(const BasicBlock *CurBB, 299 const BasicBlock *PredBB) const{ 300 return const_cast<Value*>(this)->DoPHITranslation(CurBB, PredBB); 301 } 302 303 /// MaximumAlignment - This is the greatest alignment value supported by 304 /// load, store, and alloca instructions, and global values. 305 static const unsigned MaximumAlignment = 1u << 29; 306 307protected: 308 unsigned short getSubclassDataFromValue() const { return SubclassData; } 309 void setValueSubclassData(unsigned short D) { SubclassData = D; } 310}; 311 312inline raw_ostream &operator<<(raw_ostream &OS, const Value &V) { 313 V.print(OS); 314 return OS; 315} 316 317void Use::set(Value *V) { 318 if (Val) removeFromList(); 319 Val = V; 320 if (V) V->addUse(*this); 321} 322 323 324// isa - Provide some specializations of isa so that we don't have to include 325// the subtype header files to test to see if the value is a subclass... 326// 327template <> struct isa_impl<Constant, Value> { 328 static inline bool doit(const Value &Val) { 329 return Val.getValueID() >= Value::ConstantFirstVal && 330 Val.getValueID() <= Value::ConstantLastVal; 331 } 332}; 333 334template <> struct isa_impl<Argument, Value> { 335 static inline bool doit (const Value &Val) { 336 return Val.getValueID() == Value::ArgumentVal; 337 } 338}; 339 340template <> struct isa_impl<InlineAsm, Value> { 341 static inline bool doit(const Value &Val) { 342 return Val.getValueID() == Value::InlineAsmVal; 343 } 344}; 345 346template <> struct isa_impl<Instruction, Value> { 347 static inline bool doit(const Value &Val) { 348 return Val.getValueID() >= Value::InstructionVal; 349 } 350}; 351 352template <> struct isa_impl<BasicBlock, Value> { 353 static inline bool doit(const Value &Val) { 354 return Val.getValueID() == Value::BasicBlockVal; 355 } 356}; 357 358template <> struct isa_impl<Function, Value> { 359 static inline bool doit(const Value &Val) { 360 return Val.getValueID() == Value::FunctionVal; 361 } 362}; 363 364template <> struct isa_impl<GlobalVariable, Value> { 365 static inline bool doit(const Value &Val) { 366 return Val.getValueID() == Value::GlobalVariableVal; 367 } 368}; 369 370template <> struct isa_impl<GlobalAlias, Value> { 371 static inline bool doit(const Value &Val) { 372 return Val.getValueID() == Value::GlobalAliasVal; 373 } 374}; 375 376template <> struct isa_impl<GlobalValue, Value> { 377 static inline bool doit(const Value &Val) { 378 return isa<GlobalVariable>(Val) || isa<Function>(Val) || 379 isa<GlobalAlias>(Val); 380 } 381}; 382 383template <> struct isa_impl<MDNode, Value> { 384 static inline bool doit(const Value &Val) { 385 return Val.getValueID() == Value::MDNodeVal; 386 } 387}; 388 389// Value* is only 4-byte aligned. 390template<> 391class PointerLikeTypeTraits<Value*> { 392 typedef Value* PT; 393public: 394 static inline void *getAsVoidPointer(PT P) { return P; } 395 static inline PT getFromVoidPointer(void *P) { 396 return static_cast<PT>(P); 397 } 398 enum { NumLowBitsAvailable = 2 }; 399}; 400 401} // End llvm namespace 402 403#endif 404