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/ADT/iterator_range.h"
18 #include "llvm/IR/Use.h"
19 #include "llvm/Support/CBindingWrapping.h"
20 #include "llvm/Support/Casting.h"
21 #include "llvm-c/Types.h"
32 class ConstantAggregate;
37 class GlobalIndirectSymbol;
45 class ModuleSlotTracker;
51 template<typename ValueTy> class StringMapEntry;
52 typedef StringMapEntry<Value*> ValueName;
54 //===----------------------------------------------------------------------===//
56 //===----------------------------------------------------------------------===//
58 /// \brief LLVM Value Representation
60 /// This is a very important LLVM class. It is the base class of all values
61 /// computed by a program that may be used as operands to other values. Value is
62 /// the super class of other important classes such as Instruction and Function.
63 /// All Values have a Type. Type is not a subclass of Value. Some values can
64 /// have a name and they belong to some Module. Setting the name on the Value
65 /// automatically updates the module's symbol table.
67 /// Every value has a "use list" that keeps track of which other Values are
68 /// using this Value. A Value can also have an arbitrary number of ValueHandle
69 /// objects that watch it and listen to RAUW and Destroy events. See
70 /// llvm/IR/ValueHandle.h for details.
75 friend class ValueAsMetadata; // Allow access to IsUsedByMD.
76 friend class ValueHandleBase;
78 const unsigned char SubclassID; // Subclass identifier (for isa/dyn_cast)
79 unsigned char HasValueHandle : 1; // Has a ValueHandle pointing to this?
82 /// \brief Hold subclass data that can be dropped.
84 /// This member is similar to SubclassData, however it is for holding
85 /// information which may be used to aid optimization, but which may be
86 /// cleared to zero without affecting conservative interpretation.
87 unsigned char SubclassOptionalData : 7;
90 /// \brief Hold arbitrary subclass data.
92 /// This member is defined by this class, but is not used for anything.
93 /// Subclasses can use it to hold whatever state they find useful. This
94 /// field is initialized to zero by the ctor.
95 unsigned short SubclassData;
98 /// \brief The number of operands in the subclass.
100 /// This member is defined by this class, but not used for anything.
101 /// Subclasses can use it to store their number of operands, if they have
104 /// This is stored here to save space in User on 64-bit hosts. Since most
105 /// instances of Value have operands, 32-bit hosts aren't significantly
108 /// Note, this should *NOT* be used directly by any class other than User.
109 /// User uses this value to find the Use list.
110 enum : unsigned { NumUserOperandsBits = 28 };
111 unsigned NumUserOperands : NumUserOperandsBits;
113 // Use the same type as the bitfield above so that MSVC will pack them.
114 unsigned IsUsedByMD : 1;
115 unsigned HasName : 1;
116 unsigned HasHungOffUses : 1;
117 unsigned HasDescriptor : 1;
120 template <typename UseT> // UseT == 'Use' or 'const Use'
121 class use_iterator_impl
122 : public std::iterator<std::forward_iterator_tag, UseT *> {
124 explicit use_iterator_impl(UseT *u) : U(u) {}
128 use_iterator_impl() : U() {}
130 bool operator==(const use_iterator_impl &x) const { return U == x.U; }
131 bool operator!=(const use_iterator_impl &x) const { return !operator==(x); }
133 use_iterator_impl &operator++() { // Preincrement
134 assert(U && "Cannot increment end iterator!");
139 use_iterator_impl operator++(int) { // Postincrement
145 UseT &operator*() const {
146 assert(U && "Cannot dereference end iterator!");
150 UseT *operator->() const { return &operator*(); }
152 operator use_iterator_impl<const UseT>() const {
153 return use_iterator_impl<const UseT>(U);
157 template <typename UserTy> // UserTy == 'User' or 'const User'
158 class user_iterator_impl
159 : public std::iterator<std::forward_iterator_tag, UserTy *> {
160 use_iterator_impl<Use> UI;
161 explicit user_iterator_impl(Use *U) : UI(U) {}
165 user_iterator_impl() = default;
167 bool operator==(const user_iterator_impl &x) const { return UI == x.UI; }
168 bool operator!=(const user_iterator_impl &x) const { return !operator==(x); }
170 /// \brief Returns true if this iterator is equal to user_end() on the value.
171 bool atEnd() const { return *this == user_iterator_impl(); }
173 user_iterator_impl &operator++() { // Preincrement
178 user_iterator_impl operator++(int) { // Postincrement
184 // Retrieve a pointer to the current User.
185 UserTy *operator*() const {
186 return UI->getUser();
189 UserTy *operator->() const { return operator*(); }
191 operator user_iterator_impl<const UserTy>() const {
192 return user_iterator_impl<const UserTy>(*UI);
195 Use &getUse() const { return *UI; }
199 Value(Type *Ty, unsigned scid);
202 Value(const Value &) = delete;
203 void operator=(const Value &) = delete;
206 /// \brief Support for debugging, callable in GDB: V->dump()
209 /// \brief Implement operator<< on Value.
211 void print(raw_ostream &O, bool IsForDebug = false) const;
212 void print(raw_ostream &O, ModuleSlotTracker &MST,
213 bool IsForDebug = false) const;
216 /// \brief Print the name of this Value out to the specified raw_ostream.
218 /// This is useful when you just want to print 'int %reg126', not the
219 /// instruction that generated it. If you specify a Module for context, then
220 /// even constanst get pretty-printed; for example, the type of a null
221 /// pointer is printed symbolically.
223 void printAsOperand(raw_ostream &O, bool PrintType = true,
224 const Module *M = nullptr) const;
225 void printAsOperand(raw_ostream &O, bool PrintType,
226 ModuleSlotTracker &MST) const;
229 /// \brief All values are typed, get the type of this value.
230 Type *getType() const { return VTy; }
232 /// \brief All values hold a context through their type.
233 LLVMContext &getContext() const;
235 // \brief All values can potentially be named.
236 bool hasName() const { return HasName; }
237 ValueName *getValueName() const;
238 void setValueName(ValueName *VN);
241 void destroyValueName();
242 void doRAUW(Value *New, bool NoMetadata);
243 void setNameImpl(const Twine &Name);
246 /// \brief Return a constant reference to the value's name.
248 /// This guaranteed to return the same reference as long as the value is not
249 /// modified. If the value has a name, this does a hashtable lookup, so it's
251 StringRef getName() const;
253 /// \brief Change the name of the value.
255 /// Choose a new unique name if the provided name is taken.
257 /// \param Name The new name; or "" if the value's name should be removed.
258 void setName(const Twine &Name);
260 /// \brief Transfer the name from V to this value.
262 /// After taking V's name, sets V's name to empty.
264 /// \note It is an error to call V->takeName(V).
265 void takeName(Value *V);
267 /// \brief Change all uses of this to point to a new Value.
269 /// Go through the uses list for this definition and make each use point to
270 /// "V" instead of "this". After this completes, 'this's use list is
271 /// guaranteed to be empty.
272 void replaceAllUsesWith(Value *V);
274 /// \brief Change non-metadata uses of this to point to a new Value.
276 /// Go through the uses list for this definition and make each use point to
277 /// "V" instead of "this". This function skips metadata entries in the list.
278 void replaceNonMetadataUsesWith(Value *V);
280 /// replaceUsesOutsideBlock - Go through the uses list for this definition and
281 /// make each use point to "V" instead of "this" when the use is outside the
282 /// block. 'This's use list is expected to have at least one element.
283 /// Unlike replaceAllUsesWith this function does not support basic block
284 /// values or constant users.
285 void replaceUsesOutsideBlock(Value *V, BasicBlock *BB);
287 //----------------------------------------------------------------------
288 // Methods for handling the chain of uses of this Value.
290 // Materializing a function can introduce new uses, so these methods come in
292 // The methods that start with materialized_ check the uses that are
293 // currently known given which functions are materialized. Be very careful
294 // when using them since you might not get all uses.
295 // The methods that don't start with materialized_ assert that modules is
296 // fully materialized.
297 void assertModuleIsMaterializedImpl() const;
298 // This indirection exists so we can keep assertModuleIsMaterializedImpl()
299 // around in release builds of Value.cpp to be linked with other code built
300 // in debug mode. But this avoids calling it in any of the release built code.
301 void assertModuleIsMaterialized() const {
303 assertModuleIsMaterializedImpl();
307 bool use_empty() const {
308 assertModuleIsMaterialized();
309 return UseList == nullptr;
312 typedef use_iterator_impl<Use> use_iterator;
313 typedef use_iterator_impl<const Use> const_use_iterator;
314 use_iterator materialized_use_begin() { return use_iterator(UseList); }
315 const_use_iterator materialized_use_begin() const {
316 return const_use_iterator(UseList);
318 use_iterator use_begin() {
319 assertModuleIsMaterialized();
320 return materialized_use_begin();
322 const_use_iterator use_begin() const {
323 assertModuleIsMaterialized();
324 return materialized_use_begin();
326 use_iterator use_end() { return use_iterator(); }
327 const_use_iterator use_end() const { return const_use_iterator(); }
328 iterator_range<use_iterator> materialized_uses() {
329 return make_range(materialized_use_begin(), use_end());
331 iterator_range<const_use_iterator> materialized_uses() const {
332 return make_range(materialized_use_begin(), use_end());
334 iterator_range<use_iterator> uses() {
335 assertModuleIsMaterialized();
336 return materialized_uses();
338 iterator_range<const_use_iterator> uses() const {
339 assertModuleIsMaterialized();
340 return materialized_uses();
343 bool user_empty() const {
344 assertModuleIsMaterialized();
345 return UseList == nullptr;
348 typedef user_iterator_impl<User> user_iterator;
349 typedef user_iterator_impl<const User> const_user_iterator;
350 user_iterator materialized_user_begin() { return user_iterator(UseList); }
351 const_user_iterator materialized_user_begin() const {
352 return const_user_iterator(UseList);
354 user_iterator user_begin() {
355 assertModuleIsMaterialized();
356 return materialized_user_begin();
358 const_user_iterator user_begin() const {
359 assertModuleIsMaterialized();
360 return materialized_user_begin();
362 user_iterator user_end() { return user_iterator(); }
363 const_user_iterator user_end() const { return const_user_iterator(); }
365 assertModuleIsMaterialized();
366 return *materialized_user_begin();
368 const User *user_back() const {
369 assertModuleIsMaterialized();
370 return *materialized_user_begin();
372 iterator_range<user_iterator> materialized_users() {
373 return make_range(materialized_user_begin(), user_end());
375 iterator_range<const_user_iterator> materialized_users() const {
376 return make_range(materialized_user_begin(), user_end());
378 iterator_range<user_iterator> users() {
379 assertModuleIsMaterialized();
380 return materialized_users();
382 iterator_range<const_user_iterator> users() const {
383 assertModuleIsMaterialized();
384 return materialized_users();
387 /// \brief Return true if there is exactly one user of this value.
389 /// This is specialized because it is a common request and does not require
390 /// traversing the whole use list.
391 bool hasOneUse() const {
392 const_use_iterator I = use_begin(), E = use_end();
393 if (I == E) return false;
397 /// \brief Return true if this Value has exactly N users.
398 bool hasNUses(unsigned N) const;
400 /// \brief Return true if this value has N users or more.
402 /// This is logically equivalent to getNumUses() >= N.
403 bool hasNUsesOrMore(unsigned N) const;
405 /// \brief Check if this value is used in the specified basic block.
406 bool isUsedInBasicBlock(const BasicBlock *BB) const;
408 /// \brief This method computes the number of uses of this Value.
410 /// This is a linear time operation. Use hasOneUse, hasNUses, or
411 /// hasNUsesOrMore to check for specific values.
412 unsigned getNumUses() const;
414 /// \brief This method should only be used by the Use class.
415 void addUse(Use &U) { U.addToList(&UseList); }
417 /// \brief Concrete subclass of this.
419 /// An enumeration for keeping track of the concrete subclass of Value that
420 /// is actually instantiated. Values of this enumeration are kept in the
421 /// Value classes SubclassID field. They are used for concrete type
424 #define HANDLE_VALUE(Name) Name##Val,
425 #include "llvm/IR/Value.def"
428 #define HANDLE_CONSTANT_MARKER(Marker, Constant) Marker = Constant##Val,
429 #include "llvm/IR/Value.def"
432 /// \brief Return an ID for the concrete type of this object.
434 /// This is used to implement the classof checks. This should not be used
435 /// for any other purpose, as the values may change as LLVM evolves. Also,
436 /// note that for instructions, the Instruction's opcode is added to
437 /// InstructionVal. So this means three things:
438 /// # there is no value with code InstructionVal (no opcode==0).
439 /// # there are more possible values for the value type than in ValueTy enum.
440 /// # the InstructionVal enumerator must be the highest valued enumerator in
441 /// the ValueTy enum.
442 unsigned getValueID() const {
446 /// \brief Return the raw optional flags value contained in this value.
448 /// This should only be used when testing two Values for equivalence.
449 unsigned getRawSubclassOptionalData() const {
450 return SubclassOptionalData;
453 /// \brief Clear the optional flags contained in this value.
454 void clearSubclassOptionalData() {
455 SubclassOptionalData = 0;
458 /// \brief Check the optional flags for equality.
459 bool hasSameSubclassOptionalData(const Value *V) const {
460 return SubclassOptionalData == V->SubclassOptionalData;
463 /// \brief Return true if there is a value handle associated with this value.
464 bool hasValueHandle() const { return HasValueHandle; }
466 /// \brief Return true if there is metadata referencing this value.
467 bool isUsedByMetadata() const { return IsUsedByMD; }
469 /// \brief Return true if this value is a swifterror value.
471 /// swifterror values can be either a function argument or an alloca with a
472 /// swifterror attribute.
473 bool isSwiftError() const;
475 /// \brief Strip off pointer casts, all-zero GEPs, and aliases.
477 /// Returns the original uncasted value. If this is called on a non-pointer
478 /// value, it returns 'this'.
479 const Value *stripPointerCasts() const;
480 Value *stripPointerCasts() {
481 return const_cast<Value *>(
482 static_cast<const Value *>(this)->stripPointerCasts());
485 /// \brief Strip off pointer casts and all-zero GEPs.
487 /// Returns the original uncasted value. If this is called on a non-pointer
488 /// value, it returns 'this'.
489 const Value *stripPointerCastsNoFollowAliases() const;
490 Value *stripPointerCastsNoFollowAliases() {
491 return const_cast<Value *>(
492 static_cast<const Value *>(this)->stripPointerCastsNoFollowAliases());
495 /// \brief Strip off pointer casts and all-constant inbounds GEPs.
497 /// Returns the original pointer value. If this is called on a non-pointer
498 /// value, it returns 'this'.
499 const Value *stripInBoundsConstantOffsets() const;
500 Value *stripInBoundsConstantOffsets() {
501 return const_cast<Value *>(
502 static_cast<const Value *>(this)->stripInBoundsConstantOffsets());
505 /// \brief Accumulate offsets from \a stripInBoundsConstantOffsets().
507 /// Stores the resulting constant offset stripped into the APInt provided.
508 /// The provided APInt will be extended or truncated as needed to be the
509 /// correct bitwidth for an offset of this pointer type.
511 /// If this is called on a non-pointer value, it returns 'this'.
512 const Value *stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
513 APInt &Offset) const;
514 Value *stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
516 return const_cast<Value *>(static_cast<const Value *>(this)
517 ->stripAndAccumulateInBoundsConstantOffsets(DL, Offset));
520 /// \brief Strip off pointer casts and inbounds GEPs.
522 /// Returns the original pointer value. If this is called on a non-pointer
523 /// value, it returns 'this'.
524 const Value *stripInBoundsOffsets() const;
525 Value *stripInBoundsOffsets() {
526 return const_cast<Value *>(
527 static_cast<const Value *>(this)->stripInBoundsOffsets());
530 /// \brief Returns the number of bytes known to be dereferenceable for the
533 /// If CanBeNull is set by this function the pointer can either be null or be
534 /// dereferenceable up to the returned number of bytes.
535 unsigned getPointerDereferenceableBytes(const DataLayout &DL,
536 bool &CanBeNull) const;
538 /// \brief Returns an alignment of the pointer value.
540 /// Returns an alignment which is either specified explicitly, e.g. via
541 /// align attribute of a function argument, or guaranteed by DataLayout.
542 unsigned getPointerAlignment(const DataLayout &DL) const;
544 /// \brief Translate PHI node to its predecessor from the given basic block.
546 /// If this value is a PHI node with CurBB as its parent, return the value in
547 /// the PHI node corresponding to PredBB. If not, return ourself. This is
548 /// useful if you want to know the value something has in a predecessor
550 const Value *DoPHITranslation(const BasicBlock *CurBB,
551 const BasicBlock *PredBB) const;
553 Value *DoPHITranslation(const BasicBlock *CurBB, const BasicBlock *PredBB) {
554 return const_cast<Value *>(
555 static_cast<const Value *>(this)->DoPHITranslation(CurBB, PredBB));
558 /// \brief The maximum alignment for instructions.
560 /// This is the greatest alignment value supported by load, store, and alloca
561 /// instructions, and global values.
562 static const unsigned MaxAlignmentExponent = 29;
563 static const unsigned MaximumAlignment = 1u << MaxAlignmentExponent;
565 /// \brief Mutate the type of this Value to be of the specified type.
567 /// Note that this is an extremely dangerous operation which can create
568 /// completely invalid IR very easily. It is strongly recommended that you
569 /// recreate IR objects with the right types instead of mutating them in
571 void mutateType(Type *Ty) {
575 /// \brief Sort the use-list.
577 /// Sorts the Value's use-list by Cmp using a stable mergesort. Cmp is
578 /// expected to compare two \a Use references.
579 template <class Compare> void sortUseList(Compare Cmp);
581 /// \brief Reverse the use-list.
582 void reverseUseList();
585 /// \brief Merge two lists together.
587 /// Merges \c L and \c R using \c Cmp. To enable stable sorts, always pushes
588 /// "equal" items from L before items from R.
590 /// \return the first element in the list.
592 /// \note Completely ignores \a Use::Prev (doesn't read, doesn't update).
593 template <class Compare>
594 static Use *mergeUseLists(Use *L, Use *R, Compare Cmp) {
596 Use **Next = &Merged;
621 /// \brief Tail-recursive helper for \a mergeUseLists().
623 /// \param[out] Next the first element in the list.
624 template <class Compare>
625 static void mergeUseListsImpl(Use *L, Use *R, Use **Next, Compare Cmp);
628 unsigned short getSubclassDataFromValue() const { return SubclassData; }
629 void setValueSubclassData(unsigned short D) { SubclassData = D; }
632 inline raw_ostream &operator<<(raw_ostream &OS, const Value &V) {
637 void Use::set(Value *V) {
638 if (Val) removeFromList();
640 if (V) V->addUse(*this);
643 Value *Use::operator=(Value *RHS) {
648 const Use &Use::operator=(const Use &RHS) {
653 template <class Compare> void Value::sortUseList(Compare Cmp) {
654 if (!UseList || !UseList->Next)
655 // No need to sort 0 or 1 uses.
658 // Note: this function completely ignores Prev pointers until the end when
659 // they're fixed en masse.
661 // Create a binomial vector of sorted lists, visiting uses one at a time and
662 // merging lists as necessary.
663 const unsigned MaxSlots = 32;
664 Use *Slots[MaxSlots];
666 // Collect the first use, turning it into a single-item list.
667 Use *Next = UseList->Next;
668 UseList->Next = nullptr;
669 unsigned NumSlots = 1;
672 // Collect all but the last use.
675 Next = Current->Next;
677 // Turn Current into a single-item list.
678 Current->Next = nullptr;
680 // Save Current in the first available slot, merging on collisions.
682 for (I = 0; I < NumSlots; ++I) {
686 // Merge two lists, doubling the size of Current and emptying slot I.
688 // Since the uses in Slots[I] originally preceded those in Current, send
689 // Slots[I] in as the left parameter to maintain a stable sort.
690 Current = mergeUseLists(Slots[I], Current, Cmp);
693 // Check if this is a new slot.
696 assert(NumSlots <= MaxSlots && "Use list bigger than 2^32");
699 // Found an open slot.
703 // Merge all the lists together.
704 assert(Next && "Expected one more Use");
705 assert(!Next->Next && "Expected only one Use");
707 for (unsigned I = 0; I < NumSlots; ++I)
709 // Since the uses in Slots[I] originally preceded those in UseList, send
710 // Slots[I] in as the left parameter to maintain a stable sort.
711 UseList = mergeUseLists(Slots[I], UseList, Cmp);
713 // Fix the Prev pointers.
714 for (Use *I = UseList, **Prev = &UseList; I; I = I->Next) {
720 // isa - Provide some specializations of isa so that we don't have to include
721 // the subtype header files to test to see if the value is a subclass...
723 template <> struct isa_impl<Constant, Value> {
724 static inline bool doit(const Value &Val) {
725 return Val.getValueID() >= Value::ConstantFirstVal &&
726 Val.getValueID() <= Value::ConstantLastVal;
730 template <> struct isa_impl<ConstantData, Value> {
731 static inline bool doit(const Value &Val) {
732 return Val.getValueID() >= Value::ConstantDataFirstVal &&
733 Val.getValueID() <= Value::ConstantDataLastVal;
737 template <> struct isa_impl<ConstantAggregate, Value> {
738 static inline bool doit(const Value &Val) {
739 return Val.getValueID() >= Value::ConstantAggregateFirstVal &&
740 Val.getValueID() <= Value::ConstantAggregateLastVal;
744 template <> struct isa_impl<Argument, Value> {
745 static inline bool doit (const Value &Val) {
746 return Val.getValueID() == Value::ArgumentVal;
750 template <> struct isa_impl<InlineAsm, Value> {
751 static inline bool doit(const Value &Val) {
752 return Val.getValueID() == Value::InlineAsmVal;
756 template <> struct isa_impl<Instruction, Value> {
757 static inline bool doit(const Value &Val) {
758 return Val.getValueID() >= Value::InstructionVal;
762 template <> struct isa_impl<BasicBlock, Value> {
763 static inline bool doit(const Value &Val) {
764 return Val.getValueID() == Value::BasicBlockVal;
768 template <> struct isa_impl<Function, Value> {
769 static inline bool doit(const Value &Val) {
770 return Val.getValueID() == Value::FunctionVal;
774 template <> struct isa_impl<GlobalVariable, Value> {
775 static inline bool doit(const Value &Val) {
776 return Val.getValueID() == Value::GlobalVariableVal;
780 template <> struct isa_impl<GlobalAlias, Value> {
781 static inline bool doit(const Value &Val) {
782 return Val.getValueID() == Value::GlobalAliasVal;
786 template <> struct isa_impl<GlobalIFunc, Value> {
787 static inline bool doit(const Value &Val) {
788 return Val.getValueID() == Value::GlobalIFuncVal;
792 template <> struct isa_impl<GlobalIndirectSymbol, Value> {
793 static inline bool doit(const Value &Val) {
794 return isa<GlobalAlias>(Val) || isa<GlobalIFunc>(Val);
798 template <> struct isa_impl<GlobalValue, Value> {
799 static inline bool doit(const Value &Val) {
800 return isa<GlobalObject>(Val) || isa<GlobalIndirectSymbol>(Val);
804 template <> struct isa_impl<GlobalObject, Value> {
805 static inline bool doit(const Value &Val) {
806 return isa<GlobalVariable>(Val) || isa<Function>(Val);
810 // Create wrappers for C Binding types (see CBindingWrapping.h).
811 DEFINE_ISA_CONVERSION_FUNCTIONS(Value, LLVMValueRef)
813 // Specialized opaque value conversions.
814 inline Value **unwrap(LLVMValueRef *Vals) {
815 return reinterpret_cast<Value**>(Vals);
819 inline T **unwrap(LLVMValueRef *Vals, unsigned Length) {
821 for (LLVMValueRef *I = Vals, *E = Vals + Length; I != E; ++I)
822 unwrap<T>(*I); // For side effect of calling assert on invalid usage.
825 return reinterpret_cast<T**>(Vals);
828 inline LLVMValueRef *wrap(const Value **Vals) {
829 return reinterpret_cast<LLVMValueRef*>(const_cast<Value**>(Vals));
832 } // end namespace llvm
834 #endif // LLVM_IR_VALUE_H