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 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 void print(llvm_ostream &O) const {
79 if (O.stream()) print(*O.stream());
81 virtual void print(std::ostream &O) const = 0;
83 /// All values are typed, get the type of this value.
85 inline const Type *getType() const { return Ty; }
87 // All values can potentially be named...
88 inline bool hasName() const { return !Name.empty(); }
89 inline const std::string &getName() const { return Name; }
91 void setName(const std::string &name);
93 /// replaceAllUsesWith - Go through the uses list for this definition and make
94 /// each use point to "V" instead of "this". After this completes, 'this's
95 /// use list is guaranteed to be empty.
97 void replaceAllUsesWith(Value *V);
99 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous.
100 // Only use when in type resolution situations!
101 void uncheckedReplaceAllUsesWith(Value *V);
103 //----------------------------------------------------------------------
104 // Methods for handling the vector of uses of this Value.
106 typedef value_use_iterator<User> use_iterator;
107 typedef value_use_iterator<const User> use_const_iterator;
109 bool use_empty() const { return UseList == 0; }
110 use_iterator use_begin() { return use_iterator(UseList); }
111 use_const_iterator use_begin() const { return use_const_iterator(UseList); }
112 use_iterator use_end() { return use_iterator(0); }
113 use_const_iterator use_end() const { return use_const_iterator(0); }
114 User *use_back() { return *use_begin(); }
115 const User *use_back() const { return *use_begin(); }
117 /// hasOneUse - Return true if there is exactly one user of this value. This
118 /// is specialized because it is a common request and does not require
119 /// traversing the whole use list.
121 bool hasOneUse() const {
122 use_const_iterator I = use_begin(), E = use_end();
123 if (I == E) return false;
127 /// hasNUses - Return true if this Value has exactly N users.
129 bool hasNUses(unsigned N) const;
131 /// hasNUsesOrMore - Return true if this value has N users or more. This is
132 /// logically equivalent to getNumUses() >= N.
134 bool hasNUsesOrMore(unsigned N) const;
136 /// getNumUses - This method computes the number of uses of this Value. This
137 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses
138 /// to check for specific values.
139 unsigned getNumUses() const;
141 /// addUse/killUse - These two methods should only be used by the Use class.
143 void addUse(Use &U) { U.addToList(&UseList); }
145 /// An enumeration for keeping track of the concrete subclass of Value that
146 /// is actually instantiated. Values of this enumeration are kept in the
147 /// Value classes SubclassID field. They are used for concrete type
150 ArgumentVal, // This is an instance of Argument
151 BasicBlockVal, // This is an instance of BasicBlock
152 FunctionVal, // This is an instance of Function
153 GlobalVariableVal, // This is an instance of GlobalVariable
154 UndefValueVal, // This is an instance of UndefValue
155 ConstantExprVal, // This is an instance of ConstantExpr
156 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull
157 ConstantBoolVal, // This is an instance of ConstantBool
158 ConstantIntVal, // This is an instance of ConstantInt
159 ConstantFPVal, // This is an instance of ConstantFP
160 ConstantArrayVal, // This is an instance of ConstantArray
161 ConstantStructVal, // This is an instance of ConstantStruct
162 ConstantPackedVal, // This is an instance of ConstantPacked
163 ConstantPointerNullVal, // This is an instance of ConstantPointerNull
164 InlineAsmVal, // This is an instance of InlineAsm
165 InstructionVal, // This is an instance of Instruction
168 ConstantFirstVal = FunctionVal,
169 ConstantLastVal = ConstantPointerNullVal
172 /// getValueType - Return an ID for the concrete type of this object. This is
173 /// used to implement the classof checks. This should not be used for any
174 /// other purpose, as the values may change as LLVM evolves. Also, note that
175 /// starting with the InstructionVal value, the value stored is actually the
176 /// Instruction opcode, so there are more than just these values possible here
177 /// (and Instruction must be last).
179 unsigned getValueType() const {
183 // Methods for support type inquiry through isa, cast, and dyn_cast:
184 static inline bool classof(const Value *) {
185 return true; // Values are always values.
188 /// getRawType - This should only be used to implement the vmcore library.
190 const Type *getRawType() const { return Ty.getRawType(); }
193 /// FIXME: this is a gross hack, needed by another gross hack. Eliminate!
194 void setValueType(unsigned short VT) { SubclassID = VT; }
195 friend class Instruction;
198 inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
203 void Use::init(Value *v, User *user) {
206 if (Val) Val->addUse(*this);
210 if (Val) removeFromList();
213 void Use::set(Value *V) {
214 if (Val) removeFromList();
216 if (V) V->addUse(*this);
220 // isa - Provide some specializations of isa so that we don't have to include
221 // the subtype header files to test to see if the value is a subclass...
223 template <> inline bool isa_impl<Constant, Value>(const Value &Val) {
224 return Val.getValueType() >= Value::ConstantFirstVal &&
225 Val.getValueType() <= Value::ConstantLastVal;
227 template <> inline bool isa_impl<Argument, Value>(const Value &Val) {
228 return Val.getValueType() == Value::ArgumentVal;
230 template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) {
231 return Val.getValueType() == Value::InlineAsmVal;
233 template <> inline bool isa_impl<Instruction, Value>(const Value &Val) {
234 return Val.getValueType() >= Value::InstructionVal;
236 template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) {
237 return Val.getValueType() == Value::BasicBlockVal;
239 template <> inline bool isa_impl<Function, Value>(const Value &Val) {
240 return Val.getValueType() == Value::FunctionVal;
242 template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) {
243 return Val.getValueType() == Value::GlobalVariableVal;
245 template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) {
246 return isa<GlobalVariable>(Val) || isa<Function>(Val);
249 } // End llvm namespace