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"
36 //===----------------------------------------------------------------------===//
38 //===----------------------------------------------------------------------===//
40 /// This is a very important LLVM class. It is the base class of all values
41 /// computed by a program that may be used as operands to other values. Value is
42 /// the super class of other important classes such as Instruction and Function.
43 /// All Values have a Type. Type is not a subclass of Value. All types can have
44 /// a name and they should belong to some Module. Setting the name on the Value
45 /// automatically update's the module's symbol table.
47 /// Every value has a "use list" that keeps track of which other Values are
49 /// @brief LLVM Value Representation
51 const unsigned short SubclassID; // Subclass identifier (for isa/dyn_cast)
53 /// SubclassData - This member is defined by this class, but is not used for
54 /// anything. Subclasses can use it to hold whatever state they find useful.
55 /// This field is initialized to zero by the ctor.
56 unsigned short SubclassData;
61 friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name.
62 friend class SymbolTable; // Allow SymbolTable to directly poke Name.
65 void operator=(const Value &); // Do not implement
66 Value(const Value &); // Do not implement
69 Value(const Type *Ty, unsigned scid, const std::string &name = "");
72 /// dump - Support for debugging, callable in GDB: V->dump()
74 virtual void dump() const;
76 /// print - Implement operator<< on Value...
78 virtual void print(std::ostream &O) const = 0;
79 void print(std::ostream *O) const { if (O) print(*O); }
81 /// All values are typed, get the type of this value.
83 inline const Type *getType() const { return Ty; }
85 // All values can potentially be named...
86 inline bool hasName() const { return !Name.empty(); }
87 inline const std::string &getName() const { return Name; }
89 void setName(const std::string &name);
91 /// replaceAllUsesWith - Go through the uses list for this definition and make
92 /// each use point to "V" instead of "this". After this completes, 'this's
93 /// use list is guaranteed to be empty.
95 void replaceAllUsesWith(Value *V);
97 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous.
98 // Only use when in type resolution situations!
99 void uncheckedReplaceAllUsesWith(Value *V);
101 //----------------------------------------------------------------------
102 // Methods for handling the vector of uses of this Value.
104 typedef value_use_iterator<User> use_iterator;
105 typedef value_use_iterator<const User> use_const_iterator;
107 bool use_empty() const { return UseList == 0; }
108 use_iterator use_begin() { return use_iterator(UseList); }
109 use_const_iterator use_begin() const { return use_const_iterator(UseList); }
110 use_iterator use_end() { return use_iterator(0); }
111 use_const_iterator use_end() const { return use_const_iterator(0); }
112 User *use_back() { return *use_begin(); }
113 const User *use_back() const { return *use_begin(); }
115 /// hasOneUse - Return true if there is exactly one user of this value. This
116 /// is specialized because it is a common request and does not require
117 /// traversing the whole use list.
119 bool hasOneUse() const {
120 use_const_iterator I = use_begin(), E = use_end();
121 if (I == E) return false;
125 /// hasNUses - Return true if this Value has exactly N users.
127 bool hasNUses(unsigned N) const;
129 /// hasNUsesOrMore - Return true if this value has N users or more. This is
130 /// logically equivalent to getNumUses() >= N.
132 bool hasNUsesOrMore(unsigned N) const;
134 /// getNumUses - This method computes the number of uses of this Value. This
135 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses
136 /// to check for specific values.
137 unsigned getNumUses() const;
139 /// addUse/killUse - These two methods should only be used by the Use class.
141 void addUse(Use &U) { U.addToList(&UseList); }
143 /// An enumeration for keeping track of the concrete subclass of Value that
144 /// is actually instantiated. Values of this enumeration are kept in the
145 /// Value classes SubclassID field. They are used for concrete type
148 ArgumentVal, // This is an instance of Argument
149 BasicBlockVal, // This is an instance of BasicBlock
150 FunctionVal, // This is an instance of Function
151 GlobalVariableVal, // This is an instance of GlobalVariable
152 UndefValueVal, // This is an instance of UndefValue
153 ConstantExprVal, // This is an instance of ConstantExpr
154 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull
155 ConstantIntVal, // This is an instance of ConstantInt
156 ConstantFPVal, // This is an instance of ConstantFP
157 ConstantArrayVal, // This is an instance of ConstantArray
158 ConstantStructVal, // This is an instance of ConstantStruct
159 ConstantPackedVal, // This is an instance of ConstantPacked
160 ConstantPointerNullVal, // This is an instance of ConstantPointerNull
161 InlineAsmVal, // This is an instance of InlineAsm
162 InstructionVal, // This is an instance of Instruction
165 ConstantFirstVal = FunctionVal,
166 ConstantLastVal = ConstantPointerNullVal
169 /// getValueType - Return an ID for the concrete type of this object. This is
170 /// used to implement the classof checks. This should not be used for any
171 /// other purpose, as the values may change as LLVM evolves. Also, note that
172 /// starting with the InstructionVal value, the value stored is actually the
173 /// Instruction opcode, so there are more than just these values possible here
174 /// (and Instruction must be last).
176 unsigned getValueType() const {
180 // Methods for support type inquiry through isa, cast, and dyn_cast:
181 static inline bool classof(const Value *) {
182 return true; // Values are always values.
185 /// getRawType - This should only be used to implement the vmcore library.
187 const Type *getRawType() const { return Ty.getRawType(); }
190 inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
195 void Use::init(Value *v, User *user) {
198 if (Val) Val->addUse(*this);
202 if (Val) removeFromList();
205 void Use::set(Value *V) {
206 if (Val) removeFromList();
208 if (V) V->addUse(*this);
212 // isa - Provide some specializations of isa so that we don't have to include
213 // the subtype header files to test to see if the value is a subclass...
215 template <> inline bool isa_impl<Constant, Value>(const Value &Val) {
216 return Val.getValueType() >= Value::ConstantFirstVal &&
217 Val.getValueType() <= Value::ConstantLastVal;
219 template <> inline bool isa_impl<Argument, Value>(const Value &Val) {
220 return Val.getValueType() == Value::ArgumentVal;
222 template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) {
223 return Val.getValueType() == Value::InlineAsmVal;
225 template <> inline bool isa_impl<Instruction, Value>(const Value &Val) {
226 return Val.getValueType() >= Value::InstructionVal;
228 template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) {
229 return Val.getValueType() == Value::BasicBlockVal;
231 template <> inline bool isa_impl<Function, Value>(const Value &Val) {
232 return Val.getValueType() == Value::FunctionVal;
234 template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) {
235 return Val.getValueType() == Value::GlobalVariableVal;
237 template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) {
238 return isa<GlobalVariable>(Val) || isa<Function>(Val);
241 } // End llvm namespace