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 typedef StringMapEntry<Value*> ValueName;
39 class AssemblyAnnotationWriter;
41 //===----------------------------------------------------------------------===//
43 //===----------------------------------------------------------------------===//
45 /// This is a very important LLVM class. It is the base class of all values
46 /// computed by a program that may be used as operands to other values. Value is
47 /// the super class of other important classes such as Instruction and Function.
48 /// All Values have a Type. Type is not a subclass of Value. All types can have
49 /// a name and they should belong to some Module. Setting the name on the Value
50 /// automatically updates the module's symbol table.
52 /// Every value has a "use list" that keeps track of which other Values are
54 /// @brief LLVM Value Representation
56 const unsigned short SubclassID; // Subclass identifier (for isa/dyn_cast)
58 /// SubclassData - This member is defined by this class, but is not used for
59 /// anything. Subclasses can use it to hold whatever state they find useful.
60 /// This field is initialized to zero by the ctor.
61 unsigned short SubclassData;
66 friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name.
67 friend class SymbolTable; // Allow SymbolTable to directly poke Name.
70 void operator=(const Value &); // Do not implement
71 Value(const Value &); // Do not implement
74 Value(const Type *Ty, unsigned scid);
77 /// dump - Support for debugging, callable in GDB: V->dump()
79 virtual void dump() const;
81 /// print - Implement operator<< on Value.
83 void print(std::ostream &O, AssemblyAnnotationWriter *AAW = 0) const;
84 void print(raw_ostream &O, AssemblyAnnotationWriter *AAW = 0) const;
86 /// All values are typed, get the type of this value.
88 inline const Type *getType() const { return VTy; }
90 // All values can potentially be named...
91 inline bool hasName() const { return Name != 0; }
92 ValueName *getValueName() const { return Name; }
94 /// getNameStart - Return a pointer to a null terminated string for this name.
95 /// Note that names can have null characters within the string as well as at
96 /// their end. This always returns a non-null pointer.
97 const char *getNameStart() const;
98 /// getNameEnd - Return a pointer to the end of the name.
99 const char *getNameEnd() const { return getNameStart() + getNameLen(); }
101 /// isName - Return true if this value has the name specified by the provided
102 /// nul terminated string.
103 bool isName(const char *N) const;
105 /// getNameLen - Return the length of the string, correctly handling nul
106 /// characters embedded into them.
107 unsigned getNameLen() const;
109 /// getName()/getNameStr() - Return the name of the specified value,
110 /// *constructing a string* to hold it. Because these are guaranteed to
111 /// construct a string, they are very expensive and should be avoided.
112 std::string getName() const { return getNameStr(); }
113 std::string getNameStr() const;
116 void setName(const std::string &name);
117 void setName(const char *Name, unsigned NameLen);
118 void setName(const char *Name); // Takes a null-terminated string.
121 /// takeName - transfer the name from V to this value, setting V's name to
122 /// empty. It is an error to call V->takeName(V).
123 void takeName(Value *V);
125 /// replaceAllUsesWith - Go through the uses list for this definition and make
126 /// each use point to "V" instead of "this". After this completes, 'this's
127 /// use list is guaranteed to be empty.
129 void replaceAllUsesWith(Value *V);
131 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous.
132 // Only use when in type resolution situations!
133 void uncheckedReplaceAllUsesWith(Value *V);
135 //----------------------------------------------------------------------
136 // Methods for handling the chain of uses of this Value.
138 typedef value_use_iterator<User> use_iterator;
139 typedef value_use_iterator<const User> use_const_iterator;
141 bool use_empty() const { return UseList == 0; }
142 use_iterator use_begin() { return use_iterator(UseList); }
143 use_const_iterator use_begin() const { return use_const_iterator(UseList); }
144 use_iterator use_end() { return use_iterator(0); }
145 use_const_iterator use_end() const { return use_const_iterator(0); }
146 User *use_back() { return *use_begin(); }
147 const User *use_back() const { return *use_begin(); }
149 /// hasOneUse - Return true if there is exactly one user of this value. This
150 /// is specialized because it is a common request and does not require
151 /// traversing the whole use list.
153 bool hasOneUse() const {
154 use_const_iterator I = use_begin(), E = use_end();
155 if (I == E) return false;
159 /// hasNUses - Return true if this Value has exactly N users.
161 bool hasNUses(unsigned N) const;
163 /// hasNUsesOrMore - Return true if this value has N users or more. This is
164 /// logically equivalent to getNumUses() >= N.
166 bool hasNUsesOrMore(unsigned N) const;
168 bool isUsedInBasicBlock(const BasicBlock *BB) const;
170 /// getNumUses - This method computes the number of uses of this Value. This
171 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses
172 /// to check for specific values.
173 unsigned getNumUses() const;
175 /// addUse - This method should only be used by the Use class.
177 void addUse(Use &U) { U.addToList(&UseList); }
179 /// An enumeration for keeping track of the concrete subclass of Value that
180 /// is actually instantiated. Values of this enumeration are kept in the
181 /// Value classes SubclassID field. They are used for concrete type
184 ArgumentVal, // This is an instance of Argument
185 BasicBlockVal, // This is an instance of BasicBlock
186 FunctionVal, // This is an instance of Function
187 GlobalAliasVal, // This is an instance of GlobalAlias
188 GlobalVariableVal, // This is an instance of GlobalVariable
189 UndefValueVal, // This is an instance of UndefValue
190 ConstantExprVal, // This is an instance of ConstantExpr
191 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull
192 ConstantIntVal, // This is an instance of ConstantInt
193 ConstantFPVal, // This is an instance of ConstantFP
194 ConstantArrayVal, // This is an instance of ConstantArray
195 ConstantStructVal, // This is an instance of ConstantStruct
196 ConstantVectorVal, // This is an instance of ConstantVector
197 ConstantPointerNullVal, // This is an instance of ConstantPointerNull
198 InlineAsmVal, // This is an instance of InlineAsm
199 PseudoSourceValueVal, // This is an instance of PseudoSourceValue
200 InstructionVal, // This is an instance of Instruction
203 ConstantFirstVal = FunctionVal,
204 ConstantLastVal = ConstantPointerNullVal
207 /// getValueID - Return an ID for the concrete type of this object. This is
208 /// used to implement the classof checks. This should not be used for any
209 /// other purpose, as the values may change as LLVM evolves. Also, note that
210 /// for instructions, the Instruction's opcode is added to InstructionVal. So
211 /// this means three things:
212 /// # there is no value with code InstructionVal (no opcode==0).
213 /// # there are more possible values for the value type than in ValueTy enum.
214 /// # the InstructionVal enumerator must be the highest valued enumerator in
215 /// the ValueTy enum.
216 unsigned getValueID() const {
220 // Methods for support type inquiry through isa, cast, and dyn_cast:
221 static inline bool classof(const Value *) {
222 return true; // Values are always values.
225 /// getRawType - This should only be used to implement the vmcore library.
227 const Type *getRawType() const { return VTy.getRawType(); }
229 /// stripPointerCasts - This method strips off any unneeded pointer
230 /// casts from the specified value, returning the original uncasted value.
231 /// Note that the returned value has pointer type if the specified value does.
232 Value *stripPointerCasts();
233 const Value *stripPointerCasts() const {
234 return const_cast<Value*>(this)->stripPointerCasts();
237 /// getUnderlyingObject - This method strips off any GEP address adjustments
238 /// and pointer casts from the specified value, returning the original object
239 /// being addressed. Note that the returned value has pointer type if the
240 /// specified value does.
241 Value *getUnderlyingObject();
242 const Value *getUnderlyingObject() const {
243 return const_cast<Value*>(this)->getUnderlyingObject();
246 /// DoPHITranslation - If this value is a PHI node with CurBB as its parent,
247 /// return the value in the PHI node corresponding to PredBB. If not, return
248 /// ourself. This is useful if you want to know the value something has in a
249 /// predecessor block.
250 Value *DoPHITranslation(const BasicBlock *CurBB, const BasicBlock *PredBB);
252 const Value *DoPHITranslation(const BasicBlock *CurBB,
253 const BasicBlock *PredBB) const{
254 return const_cast<Value*>(this)->DoPHITranslation(CurBB, PredBB);
258 inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
262 inline raw_ostream &operator<<(raw_ostream &OS, const Value &V) {
267 void Use::set(Value *V) {
268 if (Val) removeFromList();
270 if (V) V->addUse(*this);
274 // isa - Provide some specializations of isa so that we don't have to include
275 // the subtype header files to test to see if the value is a subclass...
277 template <> inline bool isa_impl<Constant, Value>(const Value &Val) {
278 return Val.getValueID() >= Value::ConstantFirstVal &&
279 Val.getValueID() <= Value::ConstantLastVal;
281 template <> inline bool isa_impl<Argument, Value>(const Value &Val) {
282 return Val.getValueID() == Value::ArgumentVal;
284 template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) {
285 return Val.getValueID() == Value::InlineAsmVal;
287 template <> inline bool isa_impl<Instruction, Value>(const Value &Val) {
288 return Val.getValueID() >= Value::InstructionVal;
290 template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) {
291 return Val.getValueID() == Value::BasicBlockVal;
293 template <> inline bool isa_impl<Function, Value>(const Value &Val) {
294 return Val.getValueID() == Value::FunctionVal;
296 template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) {
297 return Val.getValueID() == Value::GlobalVariableVal;
299 template <> inline bool isa_impl<GlobalAlias, Value>(const Value &Val) {
300 return Val.getValueID() == Value::GlobalAliasVal;
302 template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) {
303 return isa<GlobalVariable>(Val) || isa<Function>(Val) ||
304 isa<GlobalAlias>(Val);
307 } // End llvm namespace