1 //===-- llvm/Value.h - Definition of the Value class ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file declares the Value class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_IR_VALUE_H
15 #define LLVM_IR_VALUE_H
17 #include "llvm-c/Core.h"
18 #include "llvm/ADT/iterator_range.h"
19 #include "llvm/IR/Use.h"
20 #include "llvm/Support/CBindingWrapping.h"
21 #include "llvm/Support/Casting.h"
22 #include "llvm/Support/Compiler.h"
28 class AssemblyAnnotationWriter;
44 class ValueHandleBase;
45 class ValueSymbolTable;
48 template<typename ValueTy> class StringMapEntry;
49 typedef StringMapEntry<Value*> ValueName;
51 //===----------------------------------------------------------------------===//
53 //===----------------------------------------------------------------------===//
55 /// This is a very important LLVM class. It is the base class of all values
56 /// computed by a program that may be used as operands to other values. Value is
57 /// the super class of other important classes such as Instruction and Function.
58 /// All Values have a Type. Type is not a subclass of Value. Some values can
59 /// have a name and they belong to some Module. Setting the name on the Value
60 /// automatically updates the module's symbol table.
62 /// Every value has a "use list" that keeps track of which other Values are
63 /// using this Value. A Value can also have an arbitrary number of ValueHandle
64 /// objects that watch it and listen to RAUW and Destroy events. See
65 /// llvm/IR/ValueHandle.h for details.
67 /// @brief LLVM Value Representation
69 const unsigned char SubclassID; // Subclass identifier (for isa/dyn_cast)
70 unsigned char HasValueHandle : 1; // Has a ValueHandle pointing to this?
72 /// SubclassOptionalData - This member is similar to SubclassData, however it
73 /// is for holding information which may be used to aid optimization, but
74 /// which may be cleared to zero without affecting conservative
76 unsigned char SubclassOptionalData : 7;
79 template <typename UseT> // UseT == 'Use' or 'const Use'
80 class use_iterator_impl
81 : public std::iterator<std::forward_iterator_tag, UseT *, ptrdiff_t> {
82 typedef std::iterator<std::forward_iterator_tag, UseT *, ptrdiff_t> super;
85 explicit use_iterator_impl(UseT *u) : U(u) {}
89 typedef typename super::reference reference;
90 typedef typename super::pointer pointer;
92 use_iterator_impl() : U() {}
94 bool operator==(const use_iterator_impl &x) const { return U == x.U; }
95 bool operator!=(const use_iterator_impl &x) const { return !operator==(x); }
97 use_iterator_impl &operator++() { // Preincrement
98 assert(U && "Cannot increment end iterator!");
102 use_iterator_impl operator++(int) { // Postincrement
108 UseT &operator*() const {
109 assert(U && "Cannot dereference end iterator!");
113 UseT *operator->() const { return &operator*(); }
115 operator use_iterator_impl<const UseT>() const {
116 return use_iterator_impl<const UseT>(U);
120 template <typename UserTy> // UserTy == 'User' or 'const User'
121 class user_iterator_impl
122 : public std::iterator<std::forward_iterator_tag, UserTy *, ptrdiff_t> {
123 typedef std::iterator<std::forward_iterator_tag, UserTy *, ptrdiff_t> super;
125 use_iterator_impl<Use> UI;
126 explicit user_iterator_impl(Use *U) : UI(U) {}
130 typedef typename super::reference reference;
131 typedef typename super::pointer pointer;
133 user_iterator_impl() {}
135 bool operator==(const user_iterator_impl &x) const { return UI == x.UI; }
136 bool operator!=(const user_iterator_impl &x) const { return !operator==(x); }
138 /// \brief Returns true if this iterator is equal to user_end() on the value.
139 bool atEnd() const { return *this == user_iterator_impl(); }
141 user_iterator_impl &operator++() { // Preincrement
145 user_iterator_impl operator++(int) { // Postincrement
151 // Retrieve a pointer to the current User.
152 UserTy *operator*() const {
153 return UI->getUser();
156 UserTy *operator->() const { return operator*(); }
158 operator user_iterator_impl<const UserTy>() const {
159 return user_iterator_impl<const UserTy>(*UI);
162 Use &getUse() const { return *UI; }
164 /// \brief Return the operand # of this use in its User.
165 /// FIXME: Replace all callers with a direct call to Use::getOperandNo.
166 unsigned getOperandNo() const { return UI->getOperandNo(); }
169 /// SubclassData - This member is defined by this class, but is not used for
170 /// anything. Subclasses can use it to hold whatever state they find useful.
171 /// This field is initialized to zero by the ctor.
172 unsigned short SubclassData;
177 friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name.
178 friend class ValueHandleBase;
181 void operator=(const Value &) LLVM_DELETED_FUNCTION;
182 Value(const Value &) LLVM_DELETED_FUNCTION;
185 /// printCustom - Value subclasses can override this to implement custom
186 /// printing behavior.
187 virtual void printCustom(raw_ostream &O) const;
189 Value(Type *Ty, unsigned scid);
193 /// dump - Support for debugging, callable in GDB: V->dump()
197 /// print - Implement operator<< on Value.
199 void print(raw_ostream &O) const;
201 /// \brief Print the name of this Value out to the specified raw_ostream.
202 /// This is useful when you just want to print 'int %reg126', not the
203 /// instruction that generated it. If you specify a Module for context, then
204 /// even constanst get pretty-printed; for example, the type of a null
205 /// pointer is printed symbolically.
206 void printAsOperand(raw_ostream &O, bool PrintType = true,
207 const Module *M = nullptr) const;
209 /// All values are typed, get the type of this value.
211 Type *getType() const { return VTy; }
213 /// All values hold a context through their type.
214 LLVMContext &getContext() const;
216 // All values can potentially be named.
217 bool hasName() const { return Name != nullptr && SubclassID != MDStringVal; }
218 ValueName *getValueName() const { return Name; }
219 void setValueName(ValueName *VN) { Name = VN; }
221 /// getName() - Return a constant reference to the value's name. This is cheap
222 /// and guaranteed to return the same reference as long as the value is not
224 StringRef getName() const;
226 /// setName() - Change the name of the value, choosing a new unique name if
227 /// the provided name is taken.
229 /// \param Name The new name; or "" if the value's name should be removed.
230 void setName(const Twine &Name);
233 /// takeName - transfer the name from V to this value, setting V's name to
234 /// empty. It is an error to call V->takeName(V).
235 void takeName(Value *V);
237 /// replaceAllUsesWith - Go through the uses list for this definition and make
238 /// each use point to "V" instead of "this". After this completes, 'this's
239 /// use list is guaranteed to be empty.
241 void replaceAllUsesWith(Value *V);
243 //----------------------------------------------------------------------
244 // Methods for handling the chain of uses of this Value.
246 bool use_empty() const { return UseList == nullptr; }
248 typedef use_iterator_impl<Use> use_iterator;
249 typedef use_iterator_impl<const Use> const_use_iterator;
250 use_iterator use_begin() { return use_iterator(UseList); }
251 const_use_iterator use_begin() const { return const_use_iterator(UseList); }
252 use_iterator use_end() { return use_iterator(); }
253 const_use_iterator use_end() const { return const_use_iterator(); }
254 iterator_range<use_iterator> uses() {
255 return iterator_range<use_iterator>(use_begin(), use_end());
257 iterator_range<const_use_iterator> uses() const {
258 return iterator_range<const_use_iterator>(use_begin(), use_end());
261 typedef user_iterator_impl<User> user_iterator;
262 typedef user_iterator_impl<const User> const_user_iterator;
263 user_iterator user_begin() { return user_iterator(UseList); }
264 const_user_iterator user_begin() const { return const_user_iterator(UseList); }
265 user_iterator user_end() { return user_iterator(); }
266 const_user_iterator user_end() const { return const_user_iterator(); }
267 User *user_back() { return *user_begin(); }
268 const User *user_back() const { return *user_begin(); }
269 iterator_range<user_iterator> users() {
270 return iterator_range<user_iterator>(user_begin(), user_end());
272 iterator_range<const_user_iterator> users() const {
273 return iterator_range<const_user_iterator>(user_begin(), user_end());
276 /// hasOneUse - Return true if there is exactly one user of this value. This
277 /// is specialized because it is a common request and does not require
278 /// traversing the whole use list.
280 bool hasOneUse() const {
281 const_use_iterator I = use_begin(), E = use_end();
282 if (I == E) return false;
286 /// hasNUses - Return true if this Value has exactly N users.
288 bool hasNUses(unsigned N) const;
290 /// hasNUsesOrMore - Return true if this value has N users or more. This is
291 /// logically equivalent to getNumUses() >= N.
293 bool hasNUsesOrMore(unsigned N) const;
295 bool isUsedInBasicBlock(const BasicBlock *BB) const;
297 /// getNumUses - This method computes the number of uses of this Value. This
298 /// is a linear time operation. Use hasOneUse, hasNUses, or hasNUsesOrMore
299 /// to check for specific values.
300 unsigned getNumUses() const;
302 /// addUse - This method should only be used by the Use class.
304 void addUse(Use &U) { U.addToList(&UseList); }
306 /// An enumeration for keeping track of the concrete subclass of Value that
307 /// is actually instantiated. Values of this enumeration are kept in the
308 /// Value classes SubclassID field. They are used for concrete type
311 ArgumentVal, // This is an instance of Argument
312 BasicBlockVal, // This is an instance of BasicBlock
313 FunctionVal, // This is an instance of Function
314 GlobalAliasVal, // This is an instance of GlobalAlias
315 GlobalVariableVal, // This is an instance of GlobalVariable
316 UndefValueVal, // This is an instance of UndefValue
317 BlockAddressVal, // This is an instance of BlockAddress
318 ConstantExprVal, // This is an instance of ConstantExpr
319 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateZero
320 ConstantDataArrayVal, // This is an instance of ConstantDataArray
321 ConstantDataVectorVal, // This is an instance of ConstantDataVector
322 ConstantIntVal, // This is an instance of ConstantInt
323 ConstantFPVal, // This is an instance of ConstantFP
324 ConstantArrayVal, // This is an instance of ConstantArray
325 ConstantStructVal, // This is an instance of ConstantStruct
326 ConstantVectorVal, // This is an instance of ConstantVector
327 ConstantPointerNullVal, // This is an instance of ConstantPointerNull
328 MDNodeVal, // This is an instance of MDNode
329 MDStringVal, // This is an instance of MDString
330 InlineAsmVal, // This is an instance of InlineAsm
331 InstructionVal, // This is an instance of Instruction
332 // Enum values starting at InstructionVal are used for Instructions;
333 // don't add new values here!
336 ConstantFirstVal = FunctionVal,
337 ConstantLastVal = ConstantPointerNullVal
340 /// getValueID - Return an ID for the concrete type of this object. This is
341 /// used to implement the classof checks. This should not be used for any
342 /// other purpose, as the values may change as LLVM evolves. Also, note that
343 /// for instructions, the Instruction's opcode is added to InstructionVal. So
344 /// this means three things:
345 /// # there is no value with code InstructionVal (no opcode==0).
346 /// # there are more possible values for the value type than in ValueTy enum.
347 /// # the InstructionVal enumerator must be the highest valued enumerator in
348 /// the ValueTy enum.
349 unsigned getValueID() const {
353 /// getRawSubclassOptionalData - Return the raw optional flags value
354 /// contained in this value. This should only be used when testing two
355 /// Values for equivalence.
356 unsigned getRawSubclassOptionalData() const {
357 return SubclassOptionalData;
360 /// clearSubclassOptionalData - Clear the optional flags contained in
362 void clearSubclassOptionalData() {
363 SubclassOptionalData = 0;
366 /// hasSameSubclassOptionalData - Test whether the optional flags contained
367 /// in this value are equal to the optional flags in the given value.
368 bool hasSameSubclassOptionalData(const Value *V) const {
369 return SubclassOptionalData == V->SubclassOptionalData;
372 /// intersectOptionalDataWith - Clear any optional flags in this value
373 /// that are not also set in the given value.
374 void intersectOptionalDataWith(const Value *V) {
375 SubclassOptionalData &= V->SubclassOptionalData;
378 /// hasValueHandle - Return true if there is a value handle associated with
380 bool hasValueHandle() const { return HasValueHandle; }
382 /// \brief Strips off any unneeded pointer casts, all-zero GEPs and aliases
383 /// from the specified value, returning the original uncasted value.
385 /// If this is called on a non-pointer value, it returns 'this'.
386 Value *stripPointerCasts();
387 const Value *stripPointerCasts() const {
388 return const_cast<Value*>(this)->stripPointerCasts();
391 /// \brief Strips off any unneeded pointer casts and all-zero GEPs from the
392 /// specified value, returning the original uncasted value.
394 /// If this is called on a non-pointer value, it returns 'this'.
395 Value *stripPointerCastsNoFollowAliases();
396 const Value *stripPointerCastsNoFollowAliases() const {
397 return const_cast<Value*>(this)->stripPointerCastsNoFollowAliases();
400 /// \brief Strips off unneeded pointer casts and all-constant GEPs from the
401 /// specified value, returning the original pointer value.
403 /// If this is called on a non-pointer value, it returns 'this'.
404 Value *stripInBoundsConstantOffsets();
405 const Value *stripInBoundsConstantOffsets() const {
406 return const_cast<Value*>(this)->stripInBoundsConstantOffsets();
409 /// \brief Strips like \c stripInBoundsConstantOffsets but also accumulates
410 /// the constant offset stripped.
412 /// Stores the resulting constant offset stripped into the APInt provided.
413 /// The provided APInt will be extended or truncated as needed to be the
414 /// correct bitwidth for an offset of this pointer type.
416 /// If this is called on a non-pointer value, it returns 'this'.
417 Value *stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
419 const Value *stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
420 APInt &Offset) const {
421 return const_cast<Value *>(this)
422 ->stripAndAccumulateInBoundsConstantOffsets(DL, Offset);
425 /// \brief Strips off unneeded pointer casts and any in-bounds offsets from
426 /// the specified value, returning the original pointer value.
428 /// If this is called on a non-pointer value, it returns 'this'.
429 Value *stripInBoundsOffsets();
430 const Value *stripInBoundsOffsets() const {
431 return const_cast<Value*>(this)->stripInBoundsOffsets();
434 /// isDereferenceablePointer - Test if this value is always a pointer to
435 /// allocated and suitably aligned memory for a simple load or store.
436 bool isDereferenceablePointer() const;
438 /// DoPHITranslation - If this value is a PHI node with CurBB as its parent,
439 /// return the value in the PHI node corresponding to PredBB. If not, return
440 /// ourself. This is useful if you want to know the value something has in a
441 /// predecessor block.
442 Value *DoPHITranslation(const BasicBlock *CurBB, const BasicBlock *PredBB);
444 const Value *DoPHITranslation(const BasicBlock *CurBB,
445 const BasicBlock *PredBB) const{
446 return const_cast<Value*>(this)->DoPHITranslation(CurBB, PredBB);
449 /// MaximumAlignment - This is the greatest alignment value supported by
450 /// load, store, and alloca instructions, and global values.
451 static const unsigned MaximumAlignment = 1u << 29;
453 /// mutateType - Mutate the type of this Value to be of the specified type.
454 /// Note that this is an extremely dangerous operation which can create
455 /// completely invalid IR very easily. It is strongly recommended that you
456 /// recreate IR objects with the right types instead of mutating them in
458 void mutateType(Type *Ty) {
463 unsigned short getSubclassDataFromValue() const { return SubclassData; }
464 void setValueSubclassData(unsigned short D) { SubclassData = D; }
467 inline raw_ostream &operator<<(raw_ostream &OS, const Value &V) {
472 void Use::set(Value *V) {
473 if (Val) removeFromList();
475 if (V) V->addUse(*this);
479 // isa - Provide some specializations of isa so that we don't have to include
480 // the subtype header files to test to see if the value is a subclass...
482 template <> struct isa_impl<Constant, Value> {
483 static inline bool doit(const Value &Val) {
484 return Val.getValueID() >= Value::ConstantFirstVal &&
485 Val.getValueID() <= Value::ConstantLastVal;
489 template <> struct isa_impl<Argument, Value> {
490 static inline bool doit (const Value &Val) {
491 return Val.getValueID() == Value::ArgumentVal;
495 template <> struct isa_impl<InlineAsm, Value> {
496 static inline bool doit(const Value &Val) {
497 return Val.getValueID() == Value::InlineAsmVal;
501 template <> struct isa_impl<Instruction, Value> {
502 static inline bool doit(const Value &Val) {
503 return Val.getValueID() >= Value::InstructionVal;
507 template <> struct isa_impl<BasicBlock, Value> {
508 static inline bool doit(const Value &Val) {
509 return Val.getValueID() == Value::BasicBlockVal;
513 template <> struct isa_impl<Function, Value> {
514 static inline bool doit(const Value &Val) {
515 return Val.getValueID() == Value::FunctionVal;
519 template <> struct isa_impl<GlobalVariable, Value> {
520 static inline bool doit(const Value &Val) {
521 return Val.getValueID() == Value::GlobalVariableVal;
525 template <> struct isa_impl<GlobalAlias, Value> {
526 static inline bool doit(const Value &Val) {
527 return Val.getValueID() == Value::GlobalAliasVal;
531 template <> struct isa_impl<GlobalValue, Value> {
532 static inline bool doit(const Value &Val) {
533 return isa<GlobalVariable>(Val) || isa<Function>(Val) ||
534 isa<GlobalAlias>(Val);
538 template <> struct isa_impl<MDNode, Value> {
539 static inline bool doit(const Value &Val) {
540 return Val.getValueID() == Value::MDNodeVal;
544 // Value* is only 4-byte aligned.
546 class PointerLikeTypeTraits<Value*> {
549 static inline void *getAsVoidPointer(PT P) { return P; }
550 static inline PT getFromVoidPointer(void *P) {
551 return static_cast<PT>(P);
553 enum { NumLowBitsAvailable = 2 };
556 // Create wrappers for C Binding types (see CBindingWrapping.h).
557 DEFINE_ISA_CONVERSION_FUNCTIONS(Value, LLVMValueRef)
559 /* Specialized opaque value conversions.
561 inline Value **unwrap(LLVMValueRef *Vals) {
562 return reinterpret_cast<Value**>(Vals);
566 inline T **unwrap(LLVMValueRef *Vals, unsigned Length) {
568 for (LLVMValueRef *I = Vals, *E = Vals + Length; I != E; ++I)
572 return reinterpret_cast<T**>(Vals);
575 inline LLVMValueRef *wrap(const Value **Vals) {
576 return reinterpret_cast<LLVMValueRef*>(const_cast<Value**>(Vals));
579 } // End llvm namespace