1 //===-- llvm/Value.h - Definition of the Value class ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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"
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 update's 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 std::string getName() const { return getNameStr(); }
91 std::string getNameStr() const;
92 ValueName *getValueName() const { return Name; }
94 void setName(const std::string &name);
95 void setName(const char *Name, unsigned NameLen);
96 void setName(const char *Name); // Takes a null-terminated string.
99 /// takeName - transfer the name from V to this value, setting V's name to
100 /// empty. It is an error to call V->takeName(V).
101 void takeName(Value *V);
103 /// replaceAllUsesWith - Go through the uses list for this definition and make
104 /// each use point to "V" instead of "this". After this completes, 'this's
105 /// use list is guaranteed to be empty.
107 void replaceAllUsesWith(Value *V);
109 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous.
110 // Only use when in type resolution situations!
111 void uncheckedReplaceAllUsesWith(Value *V);
113 //----------------------------------------------------------------------
114 // Methods for handling the vector of uses of this Value.
116 typedef value_use_iterator<User> use_iterator;
117 typedef value_use_iterator<const User> use_const_iterator;
119 bool use_empty() const { return UseList == 0; }
120 use_iterator use_begin() { return use_iterator(UseList); }
121 use_const_iterator use_begin() const { return use_const_iterator(UseList); }
122 use_iterator use_end() { return use_iterator(0); }
123 use_const_iterator use_end() const { return use_const_iterator(0); }
124 User *use_back() { return *use_begin(); }
125 const User *use_back() const { return *use_begin(); }
127 /// hasOneUse - Return true if there is exactly one user of this value. This
128 /// is specialized because it is a common request and does not require
129 /// traversing the whole use list.
131 bool hasOneUse() const {
132 use_const_iterator I = use_begin(), E = use_end();
133 if (I == E) return false;
137 /// hasNUses - Return true if this Value has exactly N users.
139 bool hasNUses(unsigned N) const;
141 /// hasNUsesOrMore - Return true if this value has N users or more. This is
142 /// logically equivalent to getNumUses() >= N.
144 bool hasNUsesOrMore(unsigned N) const;
146 /// getNumUses - This method computes the number of uses of this Value. This
147 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses
148 /// to check for specific values.
149 unsigned getNumUses() const;
151 /// addUse/killUse - These two methods should only be used by the Use class.
153 void addUse(Use &U) { U.addToList(&UseList); }
155 /// An enumeration for keeping track of the concrete subclass of Value that
156 /// is actually instantiated. Values of this enumeration are kept in the
157 /// Value classes SubclassID field. They are used for concrete type
160 ArgumentVal, // This is an instance of Argument
161 BasicBlockVal, // This is an instance of BasicBlock
162 FunctionVal, // This is an instance of Function
163 GlobalVariableVal, // This is an instance of GlobalVariable
164 UndefValueVal, // This is an instance of UndefValue
165 ConstantExprVal, // This is an instance of ConstantExpr
166 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull
167 ConstantIntVal, // This is an instance of ConstantInt
168 ConstantFPVal, // This is an instance of ConstantFP
169 ConstantArrayVal, // This is an instance of ConstantArray
170 ConstantStructVal, // This is an instance of ConstantStruct
171 ConstantVectorVal, // This is an instance of ConstantVector
172 ConstantPointerNullVal, // This is an instance of ConstantPointerNull
173 InlineAsmVal, // This is an instance of InlineAsm
174 InstructionVal, // This is an instance of Instruction
177 ConstantFirstVal = FunctionVal,
178 ConstantLastVal = ConstantPointerNullVal
181 /// getValueID - Return an ID for the concrete type of this object. This is
182 /// used to implement the classof checks. This should not be used for any
183 /// other purpose, as the values may change as LLVM evolves. Also, note that
184 /// for instructions, the Instruction's opcode is added to InstructionVal. So
185 /// this means three things:
186 /// # there is no value with code InstructionVal (no opcode==0).
187 /// # there are more possible values for the value type than in ValueTy enum.
188 /// # the InstructionVal enumerator must be the highest valued enumerator in
189 /// the ValueTy enum.
190 unsigned getValueID() const {
194 // Methods for support type inquiry through isa, cast, and dyn_cast:
195 static inline bool classof(const Value *) {
196 return true; // Values are always values.
199 /// getRawType - This should only be used to implement the vmcore library.
201 const Type *getRawType() const { return Ty.getRawType(); }
204 inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
209 void Use::init(Value *v, User *user) {
212 if (Val) Val->addUse(*this);
216 if (Val) removeFromList();
219 void Use::set(Value *V) {
220 if (Val) removeFromList();
222 if (V) V->addUse(*this);
226 // isa - Provide some specializations of isa so that we don't have to include
227 // the subtype header files to test to see if the value is a subclass...
229 template <> inline bool isa_impl<Constant, Value>(const Value &Val) {
230 return Val.getValueID() >= Value::ConstantFirstVal &&
231 Val.getValueID() <= Value::ConstantLastVal;
233 template <> inline bool isa_impl<Argument, Value>(const Value &Val) {
234 return Val.getValueID() == Value::ArgumentVal;
236 template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) {
237 return Val.getValueID() == Value::InlineAsmVal;
239 template <> inline bool isa_impl<Instruction, Value>(const Value &Val) {
240 return Val.getValueID() >= Value::InstructionVal;
242 template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) {
243 return Val.getValueID() == Value::BasicBlockVal;
245 template <> inline bool isa_impl<Function, Value>(const Value &Val) {
246 return Val.getValueID() == Value::FunctionVal;
248 template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) {
249 return Val.getValueID() == Value::GlobalVariableVal;
251 template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) {
252 return isa<GlobalVariable>(Val) || isa<Function>(Val);
255 } // End llvm namespace