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.
11 // This file also defines the Use<> template for users of value.
13 //===----------------------------------------------------------------------===//
18 #include "llvm/AbstractTypeUser.h"
20 #include "llvm/Support/Casting.h"
21 #include "llvm/Support/Streams.h"
35 class ValueSymbolTable;
36 class TypeSymbolTable;
37 template<typename ValueTy> class StringMapEntry;
38 typedef StringMapEntry<Value*> ValueName;
40 //===----------------------------------------------------------------------===//
42 //===----------------------------------------------------------------------===//
44 /// This is a very important LLVM class. It is the base class of all values
45 /// computed by a program that may be used as operands to other values. Value is
46 /// the super class of other important classes such as Instruction and Function.
47 /// All Values have a Type. Type is not a subclass of Value. All types can have
48 /// a name and they should belong to some Module. Setting the name on the Value
49 /// automatically update's the module's symbol table.
51 /// Every value has a "use list" that keeps track of which other Values are
53 /// @brief LLVM Value Representation
55 const unsigned short SubclassID; // Subclass identifier (for isa/dyn_cast)
57 /// SubclassData - This member is defined by this class, but is not used for
58 /// anything. Subclasses can use it to hold whatever state they find useful.
59 /// This field is initialized to zero by the ctor.
60 unsigned short SubclassData;
65 friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name.
66 friend class SymbolTable; // Allow SymbolTable to directly poke Name.
69 void operator=(const Value &); // Do not implement
70 Value(const Value &); // Do not implement
73 Value(const Type *Ty, unsigned scid);
76 /// dump - Support for debugging, callable in GDB: V->dump()
78 virtual void dump() const;
80 /// print - Implement operator<< on Value...
82 virtual void print(std::ostream &O) const = 0;
83 void print(std::ostream *O) const { if (O) print(*O); }
85 /// All values are typed, get the type of this value.
87 inline const Type *getType() const { return Ty; }
89 // All values can potentially be named...
90 inline bool hasName() const { return Name != 0; }
91 ValueName *getValueName() const { return Name; }
93 /// getNameStart - Return a pointer to a null terminated string for this name.
94 /// Note that names can have null characters within the string as well as at
95 /// their end. This always returns a non-null pointer.
96 const char *getNameStart() const;
98 /// getNameLen - Return the length of the string, correctly handling nul
99 /// characters embedded into them.
100 unsigned getNameLen() const;
102 /// getName()/getNameStr() - Return the name of the specified value,
103 /// *constructing a string* to hold it. Because these are guaranteed to
104 /// construct a string, they are very expensive and should be avoided.
105 std::string getName() const { return getNameStr(); }
106 std::string getNameStr() const;
109 void setName(const std::string &name);
110 void setName(const char *Name, unsigned NameLen);
111 void setName(const char *Name); // Takes a null-terminated string.
114 /// takeName - transfer the name from V to this value, setting V's name to
115 /// empty. It is an error to call V->takeName(V).
116 void takeName(Value *V);
118 /// replaceAllUsesWith - Go through the uses list for this definition and make
119 /// each use point to "V" instead of "this". After this completes, 'this's
120 /// use list is guaranteed to be empty.
122 void replaceAllUsesWith(Value *V);
124 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous.
125 // Only use when in type resolution situations!
126 void uncheckedReplaceAllUsesWith(Value *V);
128 //----------------------------------------------------------------------
129 // Methods for handling the vector of uses of this Value.
131 typedef value_use_iterator<User> use_iterator;
132 typedef value_use_iterator<const User> use_const_iterator;
134 bool use_empty() const { return UseList == 0; }
135 use_iterator use_begin() { return use_iterator(UseList); }
136 use_const_iterator use_begin() const { return use_const_iterator(UseList); }
137 use_iterator use_end() { return use_iterator(0); }
138 use_const_iterator use_end() const { return use_const_iterator(0); }
139 User *use_back() { return *use_begin(); }
140 const User *use_back() const { return *use_begin(); }
142 /// hasOneUse - Return true if there is exactly one user of this value. This
143 /// is specialized because it is a common request and does not require
144 /// traversing the whole use list.
146 bool hasOneUse() const {
147 use_const_iterator I = use_begin(), E = use_end();
148 if (I == E) return false;
152 /// hasNUses - Return true if this Value has exactly N users.
154 bool hasNUses(unsigned N) const;
156 /// hasNUsesOrMore - Return true if this value has N users or more. This is
157 /// logically equivalent to getNumUses() >= N.
159 bool hasNUsesOrMore(unsigned N) const;
161 /// getNumUses - This method computes the number of uses of this Value. This
162 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses
163 /// to check for specific values.
164 unsigned getNumUses() const;
166 /// addUse/killUse - These two methods should only be used by the Use class.
168 void addUse(Use &U) { U.addToList(&UseList); }
170 /// An enumeration for keeping track of the concrete subclass of Value that
171 /// is actually instantiated. Values of this enumeration are kept in the
172 /// Value classes SubclassID field. They are used for concrete type
175 ArgumentVal, // This is an instance of Argument
176 BasicBlockVal, // This is an instance of BasicBlock
177 FunctionVal, // This is an instance of Function
178 GlobalAliasVal, // This is an instance of GlobalAlias
179 GlobalVariableVal, // This is an instance of GlobalVariable
180 UndefValueVal, // This is an instance of UndefValue
181 ConstantExprVal, // This is an instance of ConstantExpr
182 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull
183 ConstantIntVal, // This is an instance of ConstantInt
184 ConstantFPVal, // This is an instance of ConstantFP
185 ConstantArrayVal, // This is an instance of ConstantArray
186 ConstantStructVal, // This is an instance of ConstantStruct
187 ConstantVectorVal, // This is an instance of ConstantVector
188 ConstantPointerNullVal, // This is an instance of ConstantPointerNull
189 InlineAsmVal, // This is an instance of InlineAsm
190 InstructionVal, // This is an instance of Instruction
193 ConstantFirstVal = FunctionVal,
194 ConstantLastVal = ConstantPointerNullVal
197 /// getValueID - Return an ID for the concrete type of this object. This is
198 /// used to implement the classof checks. This should not be used for any
199 /// other purpose, as the values may change as LLVM evolves. Also, note that
200 /// for instructions, the Instruction's opcode is added to InstructionVal. So
201 /// this means three things:
202 /// # there is no value with code InstructionVal (no opcode==0).
203 /// # there are more possible values for the value type than in ValueTy enum.
204 /// # the InstructionVal enumerator must be the highest valued enumerator in
205 /// the ValueTy enum.
206 unsigned getValueID() const {
210 // Methods for support type inquiry through isa, cast, and dyn_cast:
211 static inline bool classof(const Value *) {
212 return true; // Values are always values.
215 /// getRawType - This should only be used to implement the vmcore library.
217 const Type *getRawType() const { return Ty.getRawType(); }
220 inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
225 void Use::init(Value *v, User *user) {
228 if (Val) Val->addUse(*this);
232 if (Val) removeFromList();
235 void Use::set(Value *V) {
236 if (Val) removeFromList();
238 if (V) V->addUse(*this);
242 // isa - Provide some specializations of isa so that we don't have to include
243 // the subtype header files to test to see if the value is a subclass...
245 template <> inline bool isa_impl<Constant, Value>(const Value &Val) {
246 return Val.getValueID() >= Value::ConstantFirstVal &&
247 Val.getValueID() <= Value::ConstantLastVal;
249 template <> inline bool isa_impl<Argument, Value>(const Value &Val) {
250 return Val.getValueID() == Value::ArgumentVal;
252 template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) {
253 return Val.getValueID() == Value::InlineAsmVal;
255 template <> inline bool isa_impl<Instruction, Value>(const Value &Val) {
256 return Val.getValueID() >= Value::InstructionVal;
258 template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) {
259 return Val.getValueID() == Value::BasicBlockVal;
261 template <> inline bool isa_impl<Function, Value>(const Value &Val) {
262 return Val.getValueID() == Value::FunctionVal;
264 template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) {
265 return Val.getValueID() == Value::GlobalVariableVal;
267 template <> inline bool isa_impl<GlobalAlias, Value>(const Value &Val) {
268 return Val.getValueID() == Value::GlobalAliasVal;
270 template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) {
271 return isa<GlobalVariable>(Val) || isa<Function>(Val) || isa<GlobalAlias>(Val);
274 } // End llvm namespace