//===-- llvm/Value.h - Definition of the Value class ------------*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file declares the Value class. // //===----------------------------------------------------------------------===// #ifndef LLVM_VALUE_H #define LLVM_VALUE_H #include "llvm/AbstractTypeUser.h" #include "llvm/Use.h" #include "llvm/ADT/StringRef.h" #include "llvm/Support/Casting.h" #include <string> namespace llvm { class Constant; class Argument; class Instruction; class BasicBlock; class GlobalValue; class Function; class GlobalVariable; class GlobalAlias; class InlineAsm; class ValueSymbolTable; class TypeSymbolTable; template<typename ValueTy> class StringMapEntry; template <typename ValueTy = Value> class AssertingVH; typedef StringMapEntry<Value*> ValueName; class raw_ostream; class AssemblyAnnotationWriter; class ValueHandleBase; class LLVMContext; class Twine; class MDNode; //===----------------------------------------------------------------------===// // Value Class //===----------------------------------------------------------------------===// /// This is a very important LLVM class. It is the base class of all values /// computed by a program that may be used as operands to other values. Value is /// the super class of other important classes such as Instruction and Function. /// All Values have a Type. Type is not a subclass of Value. Some values can /// have a name and they belong to some Module. Setting the name on the Value /// automatically updates the module's symbol table. /// /// Every value has a "use list" that keeps track of which other Values are /// using this Value. A Value can also have an arbitrary number of ValueHandle /// objects that watch it and listen to RAUW and Destroy events. See /// llvm/Support/ValueHandle.h for details. /// /// @brief LLVM Value Representation class Value { const unsigned char SubclassID; // Subclass identifier (for isa/dyn_cast) unsigned char HasValueHandle : 1; // Has a ValueHandle pointing to this? protected: /// SubclassOptionalData - This member is similar to SubclassData, however it /// is for holding information which may be used to aid optimization, but /// which may be cleared to zero without affecting conservative /// interpretation. unsigned char SubclassOptionalData : 7; private: /// SubclassData - This member is defined by this class, but is not used for /// anything. Subclasses can use it to hold whatever state they find useful. /// This field is initialized to zero by the ctor. unsigned short SubclassData; PATypeHolder VTy; Use *UseList; friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name. friend class ValueHandleBase; friend class AbstractTypeUser; ValueName *Name; void operator=(const Value &); // Do not implement Value(const Value &); // Do not implement protected: /// printCustom - Value subclasses can override this to implement custom /// printing behavior. virtual void printCustom(raw_ostream &O) const; Value(const Type *Ty, unsigned scid); public: virtual ~Value(); /// dump - Support for debugging, callable in GDB: V->dump() // void dump() const; /// print - Implement operator<< on Value. /// void print(raw_ostream &O, AssemblyAnnotationWriter *AAW = 0) const; /// All values are typed, get the type of this value. /// inline const Type *getType() const { return VTy; } /// All values hold a context through their type. LLVMContext &getContext() const; // All values can potentially be named... inline bool hasName() const { return Name != 0; } ValueName *getValueName() const { return Name; } /// getName() - Return a constant reference to the value's name. This is cheap /// and guaranteed to return the same reference as long as the value is not /// modified. /// /// This is currently guaranteed to return a StringRef for which data() points /// to a valid null terminated string. The use of StringRef.data() is /// deprecated here, however, and clients should not rely on it. If such /// behavior is needed, clients should use expensive getNameStr(), or switch /// to an interface that does not depend on null termination. StringRef getName() const; /// getNameStr() - Return the name of the specified value, *constructing a /// string* to hold it. This is guaranteed to construct a string and is very /// expensive, clients should use getName() unless necessary. std::string getNameStr() const; /// setName() - Change the name of the value, choosing a new unique name if /// the provided name is taken. /// /// \arg Name - The new name; or "" if the value's name should be removed. void setName(const Twine &Name); /// takeName - transfer the name from V to this value, setting V's name to /// empty. It is an error to call V->takeName(V). void takeName(Value *V); /// replaceAllUsesWith - Go through the uses list for this definition and make /// each use point to "V" instead of "this". After this completes, 'this's /// use list is guaranteed to be empty. /// void replaceAllUsesWith(Value *V); // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous. // Only use when in type resolution situations! void uncheckedReplaceAllUsesWith(Value *V); //---------------------------------------------------------------------- // Methods for handling the chain of uses of this Value. // typedef value_use_iterator<User> use_iterator; typedef value_use_iterator<const User> const_use_iterator; bool use_empty() const { return UseList == 0; } use_iterator use_begin() { return use_iterator(UseList); } const_use_iterator use_begin() const { return const_use_iterator(UseList); } use_iterator use_end() { return use_iterator(0); } const_use_iterator use_end() const { return const_use_iterator(0); } User *use_back() { return *use_begin(); } const User *use_back() const { return *use_begin(); } /// hasOneUse - Return true if there is exactly one user of this value. This /// is specialized because it is a common request and does not require /// traversing the whole use list. /// bool hasOneUse() const { const_use_iterator I = use_begin(), E = use_end(); if (I == E) return false; return ++I == E; } /// hasNUses - Return true if this Value has exactly N users. /// bool hasNUses(unsigned N) const; /// hasNUsesOrMore - Return true if this value has N users or more. This is /// logically equivalent to getNumUses() >= N. /// bool hasNUsesOrMore(unsigned N) const; bool isUsedInBasicBlock(const BasicBlock *BB) const; /// getNumUses - This method computes the number of uses of this Value. This /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses /// to check for specific values. unsigned getNumUses() const; /// addUse - This method should only be used by the Use class. /// void addUse(Use &U) { U.addToList(&UseList); } /// An enumeration for keeping track of the concrete subclass of Value that /// is actually instantiated. Values of this enumeration are kept in the /// Value classes SubclassID field. They are used for concrete type /// identification. enum ValueTy { ArgumentVal, // This is an instance of Argument BasicBlockVal, // This is an instance of BasicBlock FunctionVal, // This is an instance of Function GlobalAliasVal, // This is an instance of GlobalAlias GlobalVariableVal, // This is an instance of GlobalVariable UndefValueVal, // This is an instance of UndefValue BlockAddressVal, // This is an instance of BlockAddress ConstantExprVal, // This is an instance of ConstantExpr ConstantAggregateZeroVal, // This is an instance of ConstantAggregateZero ConstantIntVal, // This is an instance of ConstantInt ConstantFPVal, // This is an instance of ConstantFP ConstantArrayVal, // This is an instance of ConstantArray ConstantStructVal, // This is an instance of ConstantStruct ConstantVectorVal, // This is an instance of ConstantVector ConstantPointerNullVal, // This is an instance of ConstantPointerNull MDNodeVal, // This is an instance of MDNode MDStringVal, // This is an instance of MDString InlineAsmVal, // This is an instance of InlineAsm PseudoSourceValueVal, // This is an instance of PseudoSourceValue FixedStackPseudoSourceValueVal, // This is an instance of // FixedStackPseudoSourceValue InstructionVal, // This is an instance of Instruction // Enum values starting at InstructionVal are used for Instructions; // don't add new values here! // Markers: ConstantFirstVal = FunctionVal, ConstantLastVal = ConstantPointerNullVal }; /// getValueID - Return an ID for the concrete type of this object. This is /// used to implement the classof checks. This should not be used for any /// other purpose, as the values may change as LLVM evolves. Also, note that /// for instructions, the Instruction's opcode is added to InstructionVal. So /// this means three things: /// # there is no value with code InstructionVal (no opcode==0). /// # there are more possible values for the value type than in ValueTy enum. /// # the InstructionVal enumerator must be the highest valued enumerator in /// the ValueTy enum. unsigned getValueID() const { return SubclassID; } /// getRawSubclassOptionalData - Return the raw optional flags value /// contained in this value. This should only be used when testing two /// Values for equivalence. unsigned getRawSubclassOptionalData() const { return SubclassOptionalData; } /// clearSubclassOptionalData - Clear the optional flags contained in /// this value. void clearSubclassOptionalData() { SubclassOptionalData = 0; } /// hasSameSubclassOptionalData - Test whether the optional flags contained /// in this value are equal to the optional flags in the given value. bool hasSameSubclassOptionalData(const Value *V) const { return SubclassOptionalData == V->SubclassOptionalData; } /// intersectOptionalDataWith - Clear any optional flags in this value /// that are not also set in the given value. void intersectOptionalDataWith(const Value *V) { SubclassOptionalData &= V->SubclassOptionalData; } /// hasValueHandle - Return true if there is a value handle associated with /// this value. bool hasValueHandle() const { return HasValueHandle; } // Methods for support type inquiry through isa, cast, and dyn_cast: static inline bool classof(const Value *) { return true; // Values are always values. } /// getRawType - This should only be used to implement the vmcore library. /// const Type *getRawType() const { return VTy.getRawType(); } /// stripPointerCasts - This method strips off any unneeded pointer /// casts from the specified value, returning the original uncasted value. /// Note that the returned value has pointer type if the specified value does. Value *stripPointerCasts(); const Value *stripPointerCasts() const { return const_cast<Value*>(this)->stripPointerCasts(); } /// isDereferenceablePointer - Test if this value is always a pointer to /// allocated and suitably aligned memory for a simple load or store. bool isDereferenceablePointer() const; /// DoPHITranslation - If this value is a PHI node with CurBB as its parent, /// return the value in the PHI node corresponding to PredBB. If not, return /// ourself. This is useful if you want to know the value something has in a /// predecessor block. Value *DoPHITranslation(const BasicBlock *CurBB, const BasicBlock *PredBB); const Value *DoPHITranslation(const BasicBlock *CurBB, const BasicBlock *PredBB) const{ return const_cast<Value*>(this)->DoPHITranslation(CurBB, PredBB); } /// MaximumAlignment - This is the greatest alignment value supported by /// load, store, and alloca instructions, and global values. static const unsigned MaximumAlignment = 1u << 29; protected: unsigned short getSubclassDataFromValue() const { return SubclassData; } void setValueSubclassData(unsigned short D) { SubclassData = D; } }; inline raw_ostream &operator<<(raw_ostream &OS, const Value &V) { V.print(OS); return OS; } void Use::set(Value *V) { if (Val) removeFromList(); Val = V; if (V) V->addUse(*this); } // isa - Provide some specializations of isa so that we don't have to include // the subtype header files to test to see if the value is a subclass... // template <> struct isa_impl<Constant, Value> { static inline bool doit(const Value &Val) { return Val.getValueID() >= Value::ConstantFirstVal && Val.getValueID() <= Value::ConstantLastVal; } }; template <> struct isa_impl<Argument, Value> { static inline bool doit (const Value &Val) { return Val.getValueID() == Value::ArgumentVal; } }; template <> struct isa_impl<InlineAsm, Value> { static inline bool doit(const Value &Val) { return Val.getValueID() == Value::InlineAsmVal; } }; template <> struct isa_impl<Instruction, Value> { static inline bool doit(const Value &Val) { return Val.getValueID() >= Value::InstructionVal; } }; template <> struct isa_impl<BasicBlock, Value> { static inline bool doit(const Value &Val) { return Val.getValueID() == Value::BasicBlockVal; } }; template <> struct isa_impl<Function, Value> { static inline bool doit(const Value &Val) { return Val.getValueID() == Value::FunctionVal; } }; template <> struct isa_impl<GlobalVariable, Value> { static inline bool doit(const Value &Val) { return Val.getValueID() == Value::GlobalVariableVal; } }; template <> struct isa_impl<GlobalAlias, Value> { static inline bool doit(const Value &Val) { return Val.getValueID() == Value::GlobalAliasVal; } }; template <> struct isa_impl<GlobalValue, Value> { static inline bool doit(const Value &Val) { return isa<GlobalVariable>(Val) || isa<Function>(Val) || isa<GlobalAlias>(Val); } }; template <> struct isa_impl<MDNode, Value> { static inline bool doit(const Value &Val) { return Val.getValueID() == Value::MDNodeVal; } }; // Value* is only 4-byte aligned. template<> class PointerLikeTypeTraits<Value*> { typedef Value* PT; public: static inline void *getAsVoidPointer(PT P) { return P; } static inline PT getFromVoidPointer(void *P) { return static_cast<PT>(P); } enum { NumLowBitsAvailable = 2 }; }; } // End llvm namespace #endif