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 //===----------------------------------------------------------------------===//
17 #include "llvm/AbstractTypeUser.h"
19 #include "llvm/Support/Casting.h"
34 class ValueSymbolTable;
35 class TypeSymbolTable;
36 template<typename ValueTy> class StringMapEntry;
37 template <typename ValueTy = Value>
39 typedef StringMapEntry<Value*> ValueName;
41 class AssemblyAnnotationWriter;
42 class ValueHandleBase;
44 //===----------------------------------------------------------------------===//
46 //===----------------------------------------------------------------------===//
48 /// This is a very important LLVM class. It is the base class of all values
49 /// computed by a program that may be used as operands to other values. Value is
50 /// the super class of other important classes such as Instruction and Function.
51 /// All Values have a Type. Type is not a subclass of Value. All types can have
52 /// a name and they should belong to some Module. Setting the name on the Value
53 /// automatically updates the module's symbol table.
55 /// Every value has a "use list" that keeps track of which other Values are
56 /// using this Value. A Value can also have an arbitrary number of ValueHandle
57 /// objects that watch it and listen to RAUW and Destroy events see
58 /// llvm/Support/ValueHandle.h for details.
60 /// @brief LLVM Value Representation
62 const unsigned char SubclassID; // Subclass identifier (for isa/dyn_cast)
63 unsigned char HasValueHandle : 1; // Has a ValueHandle pointing to this?
65 /// SubclassData - This member is defined by this class, but is not used for
66 /// anything. Subclasses can use it to hold whatever state they find useful.
67 /// This field is initialized to zero by the ctor.
68 unsigned short SubclassData;
73 friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name.
74 friend class SymbolTable; // Allow SymbolTable to directly poke Name.
75 friend class ValueHandleBase;
78 void operator=(const Value &); // Do not implement
79 Value(const Value &); // Do not implement
82 Value(const Type *Ty, unsigned scid);
85 /// dump - Support for debugging, callable in GDB: V->dump()
87 virtual void dump() const;
89 /// print - Implement operator<< on Value.
91 void print(std::ostream &O, AssemblyAnnotationWriter *AAW = 0) const;
92 void print(raw_ostream &O, AssemblyAnnotationWriter *AAW = 0) const;
94 /// All values are typed, get the type of this value.
96 inline const Type *getType() const { return VTy; }
98 // All values can potentially be named...
99 inline bool hasName() const { return Name != 0; }
100 ValueName *getValueName() const { return Name; }
102 /// getNameStart - Return a pointer to a null terminated string for this name.
103 /// Note that names can have null characters within the string as well as at
104 /// their end. This always returns a non-null pointer.
105 const char *getNameStart() const;
106 /// getNameEnd - Return a pointer to the end of the name.
107 const char *getNameEnd() const { return getNameStart() + getNameLen(); }
109 /// isName - Return true if this value has the name specified by the provided
110 /// nul terminated string.
111 bool isName(const char *N) const;
113 /// getNameLen - Return the length of the string, correctly handling nul
114 /// characters embedded into them.
115 unsigned getNameLen() const;
117 /// getName()/getNameStr() - Return the name of the specified value,
118 /// *constructing a string* to hold it. Because these are guaranteed to
119 /// construct a string, they are very expensive and should be avoided.
120 std::string getName() const { return getNameStr(); }
121 std::string getNameStr() const;
124 void setName(const std::string &name);
125 void setName(const char *Name, unsigned NameLen);
126 void setName(const char *Name); // Takes a null-terminated string.
129 /// takeName - transfer the name from V to this value, setting V's name to
130 /// empty. It is an error to call V->takeName(V).
131 void takeName(Value *V);
133 /// replaceAllUsesWith - Go through the uses list for this definition and make
134 /// each use point to "V" instead of "this". After this completes, 'this's
135 /// use list is guaranteed to be empty.
137 void replaceAllUsesWith(Value *V);
139 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous.
140 // Only use when in type resolution situations!
141 void uncheckedReplaceAllUsesWith(Value *V);
143 //----------------------------------------------------------------------
144 // Methods for handling the chain of uses of this Value.
146 typedef value_use_iterator<User> use_iterator;
147 typedef value_use_iterator<const User> use_const_iterator;
149 bool use_empty() const { return UseList == 0; }
150 use_iterator use_begin() { return use_iterator(UseList); }
151 use_const_iterator use_begin() const { return use_const_iterator(UseList); }
152 use_iterator use_end() { return use_iterator(0); }
153 use_const_iterator use_end() const { return use_const_iterator(0); }
154 User *use_back() { return *use_begin(); }
155 const User *use_back() const { return *use_begin(); }
157 /// hasOneUse - Return true if there is exactly one user of this value. This
158 /// is specialized because it is a common request and does not require
159 /// traversing the whole use list.
161 bool hasOneUse() const {
162 use_const_iterator I = use_begin(), E = use_end();
163 if (I == E) return false;
167 /// hasNUses - Return true if this Value has exactly N users.
169 bool hasNUses(unsigned N) const;
171 /// hasNUsesOrMore - Return true if this value has N users or more. This is
172 /// logically equivalent to getNumUses() >= N.
174 bool hasNUsesOrMore(unsigned N) const;
176 bool isUsedInBasicBlock(const BasicBlock *BB) const;
178 /// getNumUses - This method computes the number of uses of this Value. This
179 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses
180 /// to check for specific values.
181 unsigned getNumUses() const;
183 /// addUse - This method should only be used by the Use class.
185 void addUse(Use &U) { U.addToList(&UseList); }
187 /// An enumeration for keeping track of the concrete subclass of Value that
188 /// is actually instantiated. Values of this enumeration are kept in the
189 /// Value classes SubclassID field. They are used for concrete type
192 ArgumentVal, // This is an instance of Argument
193 BasicBlockVal, // This is an instance of BasicBlock
194 FunctionVal, // This is an instance of Function
195 GlobalAliasVal, // This is an instance of GlobalAlias
196 GlobalVariableVal, // This is an instance of GlobalVariable
197 UndefValueVal, // This is an instance of UndefValue
198 ConstantExprVal, // This is an instance of ConstantExpr
199 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull
200 ConstantIntVal, // This is an instance of ConstantInt
201 ConstantFPVal, // This is an instance of ConstantFP
202 ConstantArrayVal, // This is an instance of ConstantArray
203 ConstantStructVal, // This is an instance of ConstantStruct
204 ConstantVectorVal, // This is an instance of ConstantVector
205 ConstantPointerNullVal, // This is an instance of ConstantPointerNull
206 MDStringVal, // This is an instance of MDString
207 MDNodeVal, // This is an instance of MDNode
208 InlineAsmVal, // This is an instance of InlineAsm
209 PseudoSourceValueVal, // This is an instance of PseudoSourceValue
210 InstructionVal, // This is an instance of Instruction
213 ConstantFirstVal = FunctionVal,
214 ConstantLastVal = MDNodeVal
217 /// getValueID - Return an ID for the concrete type of this object. This is
218 /// used to implement the classof checks. This should not be used for any
219 /// other purpose, as the values may change as LLVM evolves. Also, note that
220 /// for instructions, the Instruction's opcode is added to InstructionVal. So
221 /// this means three things:
222 /// # there is no value with code InstructionVal (no opcode==0).
223 /// # there are more possible values for the value type than in ValueTy enum.
224 /// # the InstructionVal enumerator must be the highest valued enumerator in
225 /// the ValueTy enum.
226 unsigned getValueID() const {
230 // Methods for support type inquiry through isa, cast, and dyn_cast:
231 static inline bool classof(const Value *) {
232 return true; // Values are always values.
235 /// getRawType - This should only be used to implement the vmcore library.
237 const Type *getRawType() const { return VTy.getRawType(); }
239 /// stripPointerCasts - This method strips off any unneeded pointer
240 /// casts from the specified value, returning the original uncasted value.
241 /// Note that the returned value has pointer type if the specified value does.
242 Value *stripPointerCasts();
243 const Value *stripPointerCasts() const {
244 return const_cast<Value*>(this)->stripPointerCasts();
247 /// getUnderlyingObject - This method strips off any GEP address adjustments
248 /// and pointer casts from the specified value, returning the original object
249 /// being addressed. Note that the returned value has pointer type if the
250 /// specified value does.
251 Value *getUnderlyingObject();
252 const Value *getUnderlyingObject() const {
253 return const_cast<Value*>(this)->getUnderlyingObject();
256 /// DoPHITranslation - If this value is a PHI node with CurBB as its parent,
257 /// return the value in the PHI node corresponding to PredBB. If not, return
258 /// ourself. This is useful if you want to know the value something has in a
259 /// predecessor block.
260 Value *DoPHITranslation(const BasicBlock *CurBB, const BasicBlock *PredBB);
262 const Value *DoPHITranslation(const BasicBlock *CurBB,
263 const BasicBlock *PredBB) const{
264 return const_cast<Value*>(this)->DoPHITranslation(CurBB, PredBB);
268 inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
272 inline raw_ostream &operator<<(raw_ostream &OS, const Value &V) {
277 void Use::set(Value *V) {
278 if (Val) removeFromList();
280 if (V) V->addUse(*this);
284 // isa - Provide some specializations of isa so that we don't have to include
285 // the subtype header files to test to see if the value is a subclass...
287 template <> inline bool isa_impl<Constant, Value>(const Value &Val) {
288 return Val.getValueID() >= Value::ConstantFirstVal &&
289 Val.getValueID() <= Value::ConstantLastVal;
291 template <> inline bool isa_impl<Argument, Value>(const Value &Val) {
292 return Val.getValueID() == Value::ArgumentVal;
294 template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) {
295 return Val.getValueID() == Value::InlineAsmVal;
297 template <> inline bool isa_impl<Instruction, Value>(const Value &Val) {
298 return Val.getValueID() >= Value::InstructionVal;
300 template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) {
301 return Val.getValueID() == Value::BasicBlockVal;
303 template <> inline bool isa_impl<Function, Value>(const Value &Val) {
304 return Val.getValueID() == Value::FunctionVal;
306 template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) {
307 return Val.getValueID() == Value::GlobalVariableVal;
309 template <> inline bool isa_impl<GlobalAlias, Value>(const Value &Val) {
310 return Val.getValueID() == Value::GlobalAliasVal;
312 template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) {
313 return isa<GlobalVariable>(Val) || isa<Function>(Val) ||
314 isa<GlobalAlias>(Val);
318 // Value* is only 4-byte aligned.
320 class PointerLikeTypeTraits<Value*> {
323 static inline void *getAsVoidPointer(PT P) { return P; }
324 static inline PT getFromVoidPointer(void *P) {
325 return static_cast<PT>(P);
327 enum { NumLowBitsAvailable = 2 };
330 } // End llvm namespace