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 //===----------------------------------------------------------------------===//
41 //===----------------------------------------------------------------------===//
43 /// This is a very important LLVM class. It is the base class of all values
44 /// computed by a program that may be used as operands to other values. Value is
45 /// the super class of other important classes such as Instruction and Function.
46 /// All Values have a Type. Type is not a subclass of Value. All types can have
47 /// a name and they should belong to some Module. Setting the name on the Value
48 /// automatically updates the module's symbol table.
50 /// Every value has a "use list" that keeps track of which other Values are
52 /// @brief LLVM Value Representation
54 const unsigned short SubclassID; // Subclass identifier (for isa/dyn_cast)
56 /// SubclassData - This member is defined by this class, but is not used for
57 /// anything. Subclasses can use it to hold whatever state they find useful.
58 /// This field is initialized to zero by the ctor.
59 unsigned short SubclassData;
64 friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name.
65 friend class SymbolTable; // Allow SymbolTable to directly poke Name.
68 void operator=(const Value &); // Do not implement
69 Value(const Value &); // Do not implement
72 Value(const Type *Ty, unsigned scid);
75 /// dump - Support for debugging, callable in GDB: V->dump()
77 virtual void dump() const;
79 /// print - Implement operator<< on Value...
81 virtual void print(std::ostream &O) const = 0;
82 void print(std::ostream *O) const { if (O) print(*O); }
84 /// All values are typed, get the type of this value.
86 inline const Type *getType() const { return Ty; }
88 // All values can potentially be named...
89 inline bool hasName() const { return Name != 0; }
90 ValueName *getValueName() const { return Name; }
92 /// getNameStart - Return a pointer to a null terminated string for this name.
93 /// Note that names can have null characters within the string as well as at
94 /// their end. This always returns a non-null pointer.
95 const char *getNameStart() const;
96 /// getNameEnd - Return a pointer to the end of the name.
97 const char *getNameEnd() const { return getNameStart() + getNameLen(); }
99 /// isName - Return true if this value has the name specified by the provided
100 /// nul terminated string.
101 bool isName(const char *N) const;
103 /// getNameLen - Return the length of the string, correctly handling nul
104 /// characters embedded into them.
105 unsigned getNameLen() const;
107 /// getName()/getNameStr() - Return the name of the specified value,
108 /// *constructing a string* to hold it. Because these are guaranteed to
109 /// construct a string, they are very expensive and should be avoided.
110 std::string getName() const { return getNameStr(); }
111 std::string getNameStr() const;
114 void setName(const std::string &name);
115 void setName(const char *Name, unsigned NameLen);
116 void setName(const char *Name); // Takes a null-terminated string.
119 /// takeName - transfer the name from V to this value, setting V's name to
120 /// empty. It is an error to call V->takeName(V).
121 void takeName(Value *V);
123 /// replaceAllUsesWith - Go through the uses list for this definition and make
124 /// each use point to "V" instead of "this". After this completes, 'this's
125 /// use list is guaranteed to be empty.
127 void replaceAllUsesWith(Value *V);
129 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous.
130 // Only use when in type resolution situations!
131 void uncheckedReplaceAllUsesWith(Value *V);
133 //----------------------------------------------------------------------
134 // Methods for handling the vector of uses of this Value.
136 typedef value_use_iterator<User> use_iterator;
137 typedef value_use_iterator<const User> use_const_iterator;
139 bool use_empty() const { return UseList == 0; }
140 use_iterator use_begin() { return use_iterator(UseList); }
141 use_const_iterator use_begin() const { return use_const_iterator(UseList); }
142 use_iterator use_end() { return use_iterator(0); }
143 use_const_iterator use_end() const { return use_const_iterator(0); }
144 User *use_back() { return *use_begin(); }
145 const User *use_back() const { return *use_begin(); }
147 /// hasOneUse - Return true if there is exactly one user of this value. This
148 /// is specialized because it is a common request and does not require
149 /// traversing the whole use list.
151 bool hasOneUse() const {
152 use_const_iterator I = use_begin(), E = use_end();
153 if (I == E) return false;
157 /// hasNUses - Return true if this Value has exactly N users.
159 bool hasNUses(unsigned N) const;
161 /// hasNUsesOrMore - Return true if this value has N users or more. This is
162 /// logically equivalent to getNumUses() >= N.
164 bool hasNUsesOrMore(unsigned N) const;
166 bool isUsedInBasicBlock(BasicBlock *BB) const;
168 /// getNumUses - This method computes the number of uses of this Value. This
169 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses
170 /// to check for specific values.
171 unsigned getNumUses() const;
173 /// addUse - This method should only be used by the Use class.
175 void addUse(Use &U) { U.addToList(&UseList); }
177 /// An enumeration for keeping track of the concrete subclass of Value that
178 /// is actually instantiated. Values of this enumeration are kept in the
179 /// Value classes SubclassID field. They are used for concrete type
182 ArgumentVal, // This is an instance of Argument
183 BasicBlockVal, // This is an instance of BasicBlock
184 FunctionVal, // This is an instance of Function
185 GlobalAliasVal, // This is an instance of GlobalAlias
186 GlobalVariableVal, // This is an instance of GlobalVariable
187 UndefValueVal, // This is an instance of UndefValue
188 ConstantExprVal, // This is an instance of ConstantExpr
189 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull
190 ConstantIntVal, // This is an instance of ConstantInt
191 ConstantFPVal, // This is an instance of ConstantFP
192 ConstantArrayVal, // This is an instance of ConstantArray
193 ConstantStructVal, // This is an instance of ConstantStruct
194 ConstantVectorVal, // This is an instance of ConstantVector
195 ConstantPointerNullVal, // This is an instance of ConstantPointerNull
196 InlineAsmVal, // This is an instance of InlineAsm
197 PseudoSourceValueVal, // This is an instance of PseudoSourceValue
198 InstructionVal, // This is an instance of Instruction
201 ConstantFirstVal = FunctionVal,
202 ConstantLastVal = ConstantPointerNullVal
205 /// getValueID - Return an ID for the concrete type of this object. This is
206 /// used to implement the classof checks. This should not be used for any
207 /// other purpose, as the values may change as LLVM evolves. Also, note that
208 /// for instructions, the Instruction's opcode is added to InstructionVal. So
209 /// this means three things:
210 /// # there is no value with code InstructionVal (no opcode==0).
211 /// # there are more possible values for the value type than in ValueTy enum.
212 /// # the InstructionVal enumerator must be the highest valued enumerator in
213 /// the ValueTy enum.
214 unsigned getValueID() const {
218 // Methods for support type inquiry through isa, cast, and dyn_cast:
219 static inline bool classof(const Value *) {
220 return true; // Values are always values.
223 /// getRawType - This should only be used to implement the vmcore library.
225 const Type *getRawType() const { return Ty.getRawType(); }
227 /// stripPointerCasts - This method strips off any unneeded pointer
228 /// casts from the specified value, returning the original uncasted value.
229 /// Note that the returned value is guaranteed to have pointer type.
230 Value *stripPointerCasts();
231 const Value *stripPointerCasts() const {
232 return const_cast<Value*>(this)->stripPointerCasts();
236 inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
241 void Use::init(Value *V, User *) {
243 if (V) V->addUse(*this);
246 void Use::set(Value *V) {
247 if (Val) removeFromList();
249 if (V) V->addUse(*this);
253 // isa - Provide some specializations of isa so that we don't have to include
254 // the subtype header files to test to see if the value is a subclass...
256 template <> inline bool isa_impl<Constant, Value>(const Value &Val) {
257 return Val.getValueID() >= Value::ConstantFirstVal &&
258 Val.getValueID() <= Value::ConstantLastVal;
260 template <> inline bool isa_impl<Argument, Value>(const Value &Val) {
261 return Val.getValueID() == Value::ArgumentVal;
263 template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) {
264 return Val.getValueID() == Value::InlineAsmVal;
266 template <> inline bool isa_impl<Instruction, Value>(const Value &Val) {
267 return Val.getValueID() >= Value::InstructionVal;
269 template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) {
270 return Val.getValueID() == Value::BasicBlockVal;
272 template <> inline bool isa_impl<Function, Value>(const Value &Val) {
273 return Val.getValueID() == Value::FunctionVal;
275 template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) {
276 return Val.getValueID() == Value::GlobalVariableVal;
278 template <> inline bool isa_impl<GlobalAlias, Value>(const Value &Val) {
279 return Val.getValueID() == Value::GlobalAliasVal;
281 template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) {
282 return isa<GlobalVariable>(Val) || isa<Function>(Val) || isa<GlobalAlias>(Val);
285 } // End llvm namespace