1 //===-- llvm/Constants.h - Constant class subclass definitions --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
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.
8 //===----------------------------------------------------------------------===//
10 /// @file This file contains the declarations for the subclasses of Constant,
11 /// which represent the different flavors of constant values that live in LLVM.
12 /// Note that Constants are immutable (once created they never change) and are
13 /// fully shared by structural equivalence. This means that two structurally
14 /// equivalent constants will always have the same address. Constant's are
15 /// created on demand as needed and never deleted: thus clients don't have to
16 /// worry about the lifetime of the objects.
18 //===----------------------------------------------------------------------===//
20 #ifndef LLVM_CONSTANTS_H
21 #define LLVM_CONSTANTS_H
23 #include "llvm/Constant.h"
24 #include "llvm/Type.h"
25 #include "llvm/ADT/APInt.h"
34 template<class ConstantClass, class TypeClass, class ValType>
35 struct ConstantCreator;
36 template<class ConstantClass, class TypeClass>
37 struct ConvertConstantType;
39 //===----------------------------------------------------------------------===//
40 /// This is the shared class of boolean and integer constants. This class
41 /// represents both boolean and integral constants.
42 /// @brief Class for constant integers.
43 class ConstantInt : public Constant {
44 static ConstantInt *TheTrueVal, *TheFalseVal;
45 ConstantInt(const ConstantInt &); // DO NOT IMPLEMENT
46 ConstantInt(const IntegerType *Ty, const APInt& V);
49 /// Return the constant as an APInt value reference. This allows clients to
50 /// obtain a copy of the value, with all its precision in tact.
51 /// @brief Return the constant's value.
52 inline const APInt& getValue() const {
56 /// Return the constant as a 64-bit unsigned integer value after it
57 /// has been zero extended as appropriate for the type of this constant. Note
58 /// that this method can assert if the value does not fit in 64 bits.
60 /// @brief Return the zero extended value.
61 inline uint64_t getZExtValue() const {
62 return Val.getZExtValue();
65 /// Return the constant as a 64-bit integer value after it has been sign
66 /// sign extended as appropriate for the type of this constant. Note that
67 /// this method can assert if the value does not fit in 64 bits.
69 /// @brief Return the sign extended value.
70 inline int64_t getSExtValue() const {
71 return Val.getSExtValue();
74 /// A helper method that can be used to determine if the constant contained
75 /// within is equal to a constant. This only works for very small values,
76 /// because this is all that can be represented with all types.
77 /// @brief Determine if this constant's value is same as an unsigned char.
78 bool equalsInt(uint64_t V) const {
82 /// getTrue/getFalse - Return the singleton true/false values.
83 static inline ConstantInt *getTrue() {
84 if (TheTrueVal) return TheTrueVal;
85 return CreateTrueFalseVals(true);
87 static inline ConstantInt *getFalse() {
88 if (TheFalseVal) return TheFalseVal;
89 return CreateTrueFalseVals(false);
92 /// Return a ConstantInt with the specified value for the specified type. The
93 /// value V will be canonicalized to a an unsigned APInt. Accessing it with
94 /// either getSExtValue() or getZExtValue() will yield a correctly sized and
95 /// signed value for the type Ty.
96 /// @brief Get a ConstantInt for a specific value.
97 static ConstantInt *get(const Type *Ty, uint64_t V);
99 /// Return a ConstantInt with the specified value and an implied Type. The
100 /// type is the integer type that corresponds to the bit width of the value.
101 static ConstantInt *get(const APInt &V);
103 /// getType - Specialize the getType() method to always return an IntegerType,
104 /// which reduces the amount of casting needed in parts of the compiler.
106 inline const IntegerType *getType() const {
107 return reinterpret_cast<const IntegerType*>(Value::getType());
110 /// This static method returns true if the type Ty is big enough to
111 /// represent the value V. This can be used to avoid having the get method
112 /// assert when V is larger than Ty can represent. Note that there are two
113 /// versions of this method, one for unsigned and one for signed integers.
114 /// Although ConstantInt canonicalizes everything to an unsigned integer,
115 /// the signed version avoids callers having to convert a signed quantity
116 /// to the appropriate unsigned type before calling the method.
117 /// @returns true if V is a valid value for type Ty
118 /// @brief Determine if the value is in range for the given type.
119 static bool isValueValidForType(const Type *Ty, uint64_t V);
120 static bool isValueValidForType(const Type *Ty, int64_t V);
122 /// This function will return true iff this constant represents the "null"
123 /// value that would be returned by the getNullValue method.
124 /// @returns true if this is the null integer value.
125 /// @brief Determine if the value is null.
126 virtual bool isNullValue() const {
130 /// This is just a convenience method to make client code smaller for a
132 /// @brief Determine if the value is one.
133 bool isUnitValue() const {
137 /// This function will return true iff every bit in this constant is set
139 /// @returns true iff this constant's bits are all set to true.
140 /// @brief Determine if the value is all ones.
141 bool isAllOnesValue() const {
142 return Val.isAllOnesValue();
145 /// This function will return true iff this constant represents the largest
146 /// value that may be represented by the constant's type.
147 /// @returns true iff this is the largest value that may be represented
149 /// @brief Determine if the value is maximal.
150 bool isMaxValue(bool isSigned) const {
152 return Val.isMaxSignedValue();
154 return Val.isMaxValue();
157 /// This function will return true iff this constant represents the smallest
158 /// value that may be represented by this constant's type.
159 /// @returns true if this is the smallest value that may be represented by
161 /// @brief Determine if the value is minimal.
162 bool isMinValue(bool isSigned) const {
164 return Val.isMinSignedValue();
166 return Val.isMinValue();
169 /// @returns the value for an integer constant of the given type that has all
170 /// its bits set to true.
171 /// @brief Get the all ones value
172 static ConstantInt *getAllOnesValue(const Type *Ty);
174 /// @brief Methods to support type inquiry through isa, cast, and dyn_cast.
175 static inline bool classof(const ConstantInt *) { return true; }
176 static bool classof(const Value *V) {
177 return V->getValueType() == ConstantIntVal;
179 static void ResetTrueFalse() { TheTrueVal = TheFalseVal = 0; }
181 static ConstantInt *CreateTrueFalseVals(bool WhichOne);
185 //===----------------------------------------------------------------------===//
186 /// ConstantFP - Floating Point Values [float, double]
188 class ConstantFP : public Constant {
190 ConstantFP(const ConstantFP &); // DO NOT IMPLEMENT
192 ConstantFP(const Type *Ty, double V);
194 /// get() - Static factory methods - Return objects of the specified value
195 static ConstantFP *get(const Type *Ty, double V);
197 /// isValueValidForType - return true if Ty is big enough to represent V.
198 static bool isValueValidForType(const Type *Ty, double V);
199 inline double getValue() const { return Val; }
201 /// isNullValue - Return true if this is the value that would be returned by
202 /// getNullValue. Don't depend on == for doubles to tell us it's zero, it
203 /// considers -0.0 to be null as well as 0.0. :(
204 virtual bool isNullValue() const;
206 /// isExactlyValue - We don't rely on operator== working on double values, as
207 /// it returns true for things that are clearly not equal, like -0.0 and 0.0.
208 /// As such, this method can be used to do an exact bit-for-bit comparison of
209 /// two floating point values.
210 bool isExactlyValue(double V) const;
212 /// Methods for support type inquiry through isa, cast, and dyn_cast:
213 static inline bool classof(const ConstantFP *) { return true; }
214 static bool classof(const Value *V) {
215 return V->getValueType() == ConstantFPVal;
219 //===----------------------------------------------------------------------===//
220 /// ConstantAggregateZero - All zero aggregate value
222 class ConstantAggregateZero : public Constant {
223 friend struct ConstantCreator<ConstantAggregateZero, Type, char>;
224 ConstantAggregateZero(const ConstantAggregateZero &); // DO NOT IMPLEMENT
226 ConstantAggregateZero(const Type *Ty)
227 : Constant(Ty, ConstantAggregateZeroVal, 0, 0) {}
229 /// get() - static factory method for creating a null aggregate. It is
230 /// illegal to call this method with a non-aggregate type.
231 static Constant *get(const Type *Ty);
233 /// isNullValue - Return true if this is the value that would be returned by
235 virtual bool isNullValue() const { return true; }
237 virtual void destroyConstant();
239 /// Methods for support type inquiry through isa, cast, and dyn_cast:
241 static bool classof(const ConstantAggregateZero *) { return true; }
242 static bool classof(const Value *V) {
243 return V->getValueType() == ConstantAggregateZeroVal;
248 //===----------------------------------------------------------------------===//
249 /// ConstantArray - Constant Array Declarations
251 class ConstantArray : public Constant {
252 friend struct ConstantCreator<ConstantArray, ArrayType,
253 std::vector<Constant*> >;
254 ConstantArray(const ConstantArray &); // DO NOT IMPLEMENT
256 ConstantArray(const ArrayType *T, const std::vector<Constant*> &Val);
259 /// get() - Static factory methods - Return objects of the specified value
260 static Constant *get(const ArrayType *T, const std::vector<Constant*> &);
261 static Constant *get(const ArrayType *T,
262 Constant*const*Vals, unsigned NumVals) {
263 // FIXME: make this the primary ctor method.
264 return get(T, std::vector<Constant*>(Vals, Vals+NumVals));
267 /// This method constructs a ConstantArray and initializes it with a text
268 /// string. The default behavior (AddNull==true) causes a null terminator to
269 /// be placed at the end of the array. This effectively increases the length
270 /// of the array by one (you've been warned). However, in some situations
271 /// this is not desired so if AddNull==false then the string is copied without
272 /// null termination.
273 static Constant *get(const std::string &Initializer, bool AddNull = true);
275 /// getType - Specialize the getType() method to always return an ArrayType,
276 /// which reduces the amount of casting needed in parts of the compiler.
278 inline const ArrayType *getType() const {
279 return reinterpret_cast<const ArrayType*>(Value::getType());
282 /// isString - This method returns true if the array is an array of sbyte or
283 /// ubyte, and if the elements of the array are all ConstantInt's.
284 bool isString() const;
286 /// isCString - This method returns true if the array is a string (see
287 /// isString) and it ends in a null byte \0 and does not contains any other
288 /// null bytes except its terminator.
289 bool isCString() const;
291 /// getAsString - If this array is isString(), then this method converts the
292 /// array to an std::string and returns it. Otherwise, it asserts out.
294 std::string getAsString() const;
296 /// isNullValue - Return true if this is the value that would be returned by
297 /// getNullValue. This always returns false because zero arrays are always
298 /// created as ConstantAggregateZero objects.
299 virtual bool isNullValue() const { return false; }
301 virtual void destroyConstant();
302 virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U);
304 /// Methods for support type inquiry through isa, cast, and dyn_cast:
305 static inline bool classof(const ConstantArray *) { return true; }
306 static bool classof(const Value *V) {
307 return V->getValueType() == ConstantArrayVal;
312 //===----------------------------------------------------------------------===//
313 // ConstantStruct - Constant Struct Declarations
315 class ConstantStruct : public Constant {
316 friend struct ConstantCreator<ConstantStruct, StructType,
317 std::vector<Constant*> >;
318 ConstantStruct(const ConstantStruct &); // DO NOT IMPLEMENT
320 ConstantStruct(const StructType *T, const std::vector<Constant*> &Val);
323 /// get() - Static factory methods - Return objects of the specified value
325 static Constant *get(const StructType *T, const std::vector<Constant*> &V);
326 static Constant *get(const std::vector<Constant*> &V, bool Packed = false);
327 static Constant *get(Constant*const* Vals, unsigned NumVals,
328 bool Packed = false) {
329 // FIXME: make this the primary ctor method.
330 return get(std::vector<Constant*>(Vals, Vals+NumVals), Packed);
333 /// getType() specialization - Reduce amount of casting...
335 inline const StructType *getType() const {
336 return reinterpret_cast<const StructType*>(Value::getType());
339 /// isNullValue - Return true if this is the value that would be returned by
340 /// getNullValue. This always returns false because zero structs are always
341 /// created as ConstantAggregateZero objects.
342 virtual bool isNullValue() const {
346 virtual void destroyConstant();
347 virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U);
349 /// Methods for support type inquiry through isa, cast, and dyn_cast:
350 static inline bool classof(const ConstantStruct *) { return true; }
351 static bool classof(const Value *V) {
352 return V->getValueType() == ConstantStructVal;
356 //===----------------------------------------------------------------------===//
357 /// ConstantVector - Constant Vector Declarations
359 class ConstantVector : public Constant {
360 friend struct ConstantCreator<ConstantVector, VectorType,
361 std::vector<Constant*> >;
362 ConstantVector(const ConstantVector &); // DO NOT IMPLEMENT
364 ConstantVector(const VectorType *T, const std::vector<Constant*> &Val);
367 /// get() - Static factory methods - Return objects of the specified value
368 static Constant *get(const VectorType *T, const std::vector<Constant*> &);
369 static Constant *get(const std::vector<Constant*> &V);
370 static Constant *get(Constant*const* Vals, unsigned NumVals) {
371 // FIXME: make this the primary ctor method.
372 return get(std::vector<Constant*>(Vals, Vals+NumVals));
375 /// getType - Specialize the getType() method to always return an VectorType,
376 /// which reduces the amount of casting needed in parts of the compiler.
378 inline const VectorType *getType() const {
379 return reinterpret_cast<const VectorType*>(Value::getType());
382 /// @returns the value for an packed integer constant of the given type that
383 /// has all its bits set to true.
384 /// @brief Get the all ones value
385 static ConstantVector *getAllOnesValue(const VectorType *Ty);
387 /// isNullValue - Return true if this is the value that would be returned by
388 /// getNullValue. This always returns false because zero arrays are always
389 /// created as ConstantAggregateZero objects.
390 virtual bool isNullValue() const { return false; }
392 /// This function will return true iff every element in this packed constant
393 /// is set to all ones.
394 /// @returns true iff this constant's emements are all set to all ones.
395 /// @brief Determine if the value is all ones.
396 bool isAllOnesValue() const;
398 virtual void destroyConstant();
399 virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U);
401 /// Methods for support type inquiry through isa, cast, and dyn_cast:
402 static inline bool classof(const ConstantVector *) { return true; }
403 static bool classof(const Value *V) {
404 return V->getValueType() == ConstantVectorVal;
408 //===----------------------------------------------------------------------===//
409 /// ConstantPointerNull - a constant pointer value that points to null
411 class ConstantPointerNull : public Constant {
412 friend struct ConstantCreator<ConstantPointerNull, PointerType, char>;
413 ConstantPointerNull(const ConstantPointerNull &); // DO NOT IMPLEMENT
415 ConstantPointerNull(const PointerType *T)
416 : Constant(reinterpret_cast<const Type*>(T),
417 Value::ConstantPointerNullVal, 0, 0) {}
421 /// get() - Static factory methods - Return objects of the specified value
422 static ConstantPointerNull *get(const PointerType *T);
424 /// isNullValue - Return true if this is the value that would be returned by
426 virtual bool isNullValue() const { return true; }
428 virtual void destroyConstant();
430 /// getType - Specialize the getType() method to always return an PointerType,
431 /// which reduces the amount of casting needed in parts of the compiler.
433 inline const PointerType *getType() const {
434 return reinterpret_cast<const PointerType*>(Value::getType());
437 /// Methods for support type inquiry through isa, cast, and dyn_cast:
438 static inline bool classof(const ConstantPointerNull *) { return true; }
439 static bool classof(const Value *V) {
440 return V->getValueType() == ConstantPointerNullVal;
445 /// ConstantExpr - a constant value that is initialized with an expression using
446 /// other constant values.
448 /// This class uses the standard Instruction opcodes to define the various
449 /// constant expressions. The Opcode field for the ConstantExpr class is
450 /// maintained in the Value::SubclassData field.
451 class ConstantExpr : public Constant {
452 friend struct ConstantCreator<ConstantExpr,Type,
453 std::pair<unsigned, std::vector<Constant*> > >;
454 friend struct ConvertConstantType<ConstantExpr, Type>;
457 ConstantExpr(const Type *Ty, unsigned Opcode, Use *Ops, unsigned NumOps)
458 : Constant(Ty, ConstantExprVal, Ops, NumOps) {
459 // Operation type (an Instruction opcode) is stored as the SubclassData.
460 SubclassData = Opcode;
463 // These private methods are used by the type resolution code to create
464 // ConstantExprs in intermediate forms.
465 static Constant *getTy(const Type *Ty, unsigned Opcode,
466 Constant *C1, Constant *C2);
467 static Constant *getCompareTy(unsigned short pred, Constant *C1,
469 static Constant *getSelectTy(const Type *Ty,
470 Constant *C1, Constant *C2, Constant *C3);
471 static Constant *getGetElementPtrTy(const Type *Ty, Constant *C,
472 Value* const *Idxs, unsigned NumIdxs);
473 static Constant *getExtractElementTy(const Type *Ty, Constant *Val,
475 static Constant *getInsertElementTy(const Type *Ty, Constant *Val,
476 Constant *Elt, Constant *Idx);
477 static Constant *getShuffleVectorTy(const Type *Ty, Constant *V1,
478 Constant *V2, Constant *Mask);
481 // Static methods to construct a ConstantExpr of different kinds. Note that
482 // these methods may return a object that is not an instance of the
483 // ConstantExpr class, because they will attempt to fold the constant
484 // expression into something simpler if possible.
486 /// Cast constant expr
488 static Constant *getTrunc (Constant *C, const Type *Ty);
489 static Constant *getSExt (Constant *C, const Type *Ty);
490 static Constant *getZExt (Constant *C, const Type *Ty);
491 static Constant *getFPTrunc (Constant *C, const Type *Ty);
492 static Constant *getFPExtend(Constant *C, const Type *Ty);
493 static Constant *getUIToFP (Constant *C, const Type *Ty);
494 static Constant *getSIToFP (Constant *C, const Type *Ty);
495 static Constant *getFPToUI (Constant *C, const Type *Ty);
496 static Constant *getFPToSI (Constant *C, const Type *Ty);
497 static Constant *getPtrToInt(Constant *C, const Type *Ty);
498 static Constant *getIntToPtr(Constant *C, const Type *Ty);
499 static Constant *getBitCast (Constant *C, const Type *Ty);
501 // @brief Convenience function for getting one of the casting operations
502 // using a CastOps opcode.
503 static Constant *getCast(
504 unsigned ops, ///< The opcode for the conversion
505 Constant *C, ///< The constant to be converted
506 const Type *Ty ///< The type to which the constant is converted
509 // @brief Create a ZExt or BitCast cast constant expression
510 static Constant *getZExtOrBitCast(
511 Constant *C, ///< The constant to zext or bitcast
512 const Type *Ty ///< The type to zext or bitcast C to
515 // @brief Create a SExt or BitCast cast constant expression
516 static Constant *getSExtOrBitCast(
517 Constant *C, ///< The constant to sext or bitcast
518 const Type *Ty ///< The type to sext or bitcast C to
521 // @brief Create a Trunc or BitCast cast constant expression
522 static Constant *getTruncOrBitCast(
523 Constant *C, ///< The constant to trunc or bitcast
524 const Type *Ty ///< The type to trunc or bitcast C to
527 /// @brief Create a BitCast or a PtrToInt cast constant expression
528 static Constant *getPointerCast(
529 Constant *C, ///< The pointer value to be casted (operand 0)
530 const Type *Ty ///< The type to which cast should be made
533 /// @brief Create a ZExt, Bitcast or Trunc for integer -> integer casts
534 static Constant *getIntegerCast(
535 Constant *C, ///< The integer constant to be casted
536 const Type *Ty, ///< The integer type to cast to
537 bool isSigned ///< Whether C should be treated as signed or not
540 /// @brief Create a FPExt, Bitcast or FPTrunc for fp -> fp casts
541 static Constant *getFPCast(
542 Constant *C, ///< The integer constant to be casted
543 const Type *Ty ///< The integer type to cast to
546 /// @brief Return true if this is a convert constant expression
549 /// @brief Return true if this is a compare constant expression
550 bool isCompare() const;
552 /// Select constant expr
554 static Constant *getSelect(Constant *C, Constant *V1, Constant *V2) {
555 return getSelectTy(V1->getType(), C, V1, V2);
558 /// getSizeOf constant expr - computes the size of a type in a target
559 /// independent way (Note: the return type is a ULong).
561 static Constant *getSizeOf(const Type *Ty);
563 /// ConstantExpr::get - Return a binary or shift operator constant expression,
564 /// folding if possible.
566 static Constant *get(unsigned Opcode, Constant *C1, Constant *C2);
568 /// @brief Return an ICmp or FCmp comparison operator constant expression.
569 static Constant *getCompare(unsigned short pred, Constant *C1, Constant *C2);
571 /// ConstantExpr::get* - Return some common constants without having to
572 /// specify the full Instruction::OPCODE identifier.
574 static Constant *getNeg(Constant *C);
575 static Constant *getNot(Constant *C);
576 static Constant *getAdd(Constant *C1, Constant *C2);
577 static Constant *getSub(Constant *C1, Constant *C2);
578 static Constant *getMul(Constant *C1, Constant *C2);
579 static Constant *getUDiv(Constant *C1, Constant *C2);
580 static Constant *getSDiv(Constant *C1, Constant *C2);
581 static Constant *getFDiv(Constant *C1, Constant *C2);
582 static Constant *getURem(Constant *C1, Constant *C2); // unsigned rem
583 static Constant *getSRem(Constant *C1, Constant *C2); // signed rem
584 static Constant *getFRem(Constant *C1, Constant *C2);
585 static Constant *getAnd(Constant *C1, Constant *C2);
586 static Constant *getOr(Constant *C1, Constant *C2);
587 static Constant *getXor(Constant *C1, Constant *C2);
588 static Constant* getICmp(unsigned short pred, Constant* LHS, Constant* RHS);
589 static Constant* getFCmp(unsigned short pred, Constant* LHS, Constant* RHS);
590 static Constant *getShl(Constant *C1, Constant *C2);
591 static Constant *getLShr(Constant *C1, Constant *C2);
592 static Constant *getAShr(Constant *C1, Constant *C2);
594 /// Getelementptr form. std::vector<Value*> is only accepted for convenience:
595 /// all elements must be Constant's.
597 static Constant *getGetElementPtr(Constant *C,
598 Constant* const *IdxList, unsigned NumIdx);
599 static Constant *getGetElementPtr(Constant *C,
600 Value* const *IdxList, unsigned NumIdx);
602 static Constant *getExtractElement(Constant *Vec, Constant *Idx);
603 static Constant *getInsertElement(Constant *Vec, Constant *Elt,Constant *Idx);
604 static Constant *getShuffleVector(Constant *V1, Constant *V2, Constant *Mask);
606 /// Floating point negation must be implemented with f(x) = -0.0 - x. This
607 /// method returns the negative zero constant for floating point or packed
608 /// floating point types; for all other types, it returns the null value.
609 static Constant *getZeroValueForNegationExpr(const Type *Ty);
611 /// isNullValue - Return true if this is the value that would be returned by
613 virtual bool isNullValue() const { return false; }
615 /// getOpcode - Return the opcode at the root of this constant expression
616 unsigned getOpcode() const { return SubclassData; }
618 /// getPredicate - Return the ICMP or FCMP predicate value. Assert if this is
619 /// not an ICMP or FCMP constant expression.
620 unsigned getPredicate() const;
622 /// getOpcodeName - Return a string representation for an opcode.
623 const char *getOpcodeName() const;
625 /// getWithOperandReplaced - Return a constant expression identical to this
626 /// one, but with the specified operand set to the specified value.
627 Constant *getWithOperandReplaced(unsigned OpNo, Constant *Op) const;
629 /// getWithOperands - This returns the current constant expression with the
630 /// operands replaced with the specified values. The specified operands must
631 /// match count and type with the existing ones.
632 Constant *getWithOperands(const std::vector<Constant*> &Ops) const;
634 virtual void destroyConstant();
635 virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U);
637 /// Override methods to provide more type information...
638 inline Constant *getOperand(unsigned i) {
639 return cast<Constant>(User::getOperand(i));
641 inline Constant *getOperand(unsigned i) const {
642 return const_cast<Constant*>(cast<Constant>(User::getOperand(i)));
646 /// Methods for support type inquiry through isa, cast, and dyn_cast:
647 static inline bool classof(const ConstantExpr *) { return true; }
648 static inline bool classof(const Value *V) {
649 return V->getValueType() == ConstantExprVal;
654 //===----------------------------------------------------------------------===//
655 /// UndefValue - 'undef' values are things that do not have specified contents.
656 /// These are used for a variety of purposes, including global variable
657 /// initializers and operands to instructions. 'undef' values can occur with
660 class UndefValue : public Constant {
661 friend struct ConstantCreator<UndefValue, Type, char>;
662 UndefValue(const UndefValue &); // DO NOT IMPLEMENT
664 UndefValue(const Type *T) : Constant(T, UndefValueVal, 0, 0) {}
666 /// get() - Static factory methods - Return an 'undef' object of the specified
669 static UndefValue *get(const Type *T);
671 /// isNullValue - Return true if this is the value that would be returned by
673 virtual bool isNullValue() const { return false; }
675 virtual void destroyConstant();
677 /// Methods for support type inquiry through isa, cast, and dyn_cast:
678 static inline bool classof(const UndefValue *) { return true; }
679 static bool classof(const Value *V) {
680 return V->getValueType() == UndefValueVal;
684 } // End llvm namespace