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;
37 //===----------------------------------------------------------------------===//
39 //===----------------------------------------------------------------------===//
41 /// This is a very important LLVM class. It is the base class of all values
42 /// computed by a program that may be used as operands to other values. Value is
43 /// the super class of other important classes such as Instruction and Function.
44 /// All Values have a Type. Type is not a subclass of Value. All types can have
45 /// a name and they should belong to some Module. Setting the name on the Value
46 /// automatically update's the module's symbol table.
48 /// Every value has a "use list" that keeps track of which other Values are
50 /// @brief LLVM Value Representation
52 const unsigned short SubclassID; // Subclass identifier (for isa/dyn_cast)
54 /// SubclassData - This member is defined by this class, but is not used for
55 /// anything. Subclasses can use it to hold whatever state they find useful.
56 /// This field is initialized to zero by the ctor.
57 unsigned short SubclassData;
62 friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name.
63 friend class SymbolTable; // Allow SymbolTable to directly poke Name.
66 void operator=(const Value &); // Do not implement
67 Value(const Value &); // Do not implement
70 Value(const Type *Ty, unsigned scid, const std::string &name = "");
73 /// dump - Support for debugging, callable in GDB: V->dump()
75 virtual void dump() const;
77 /// print - Implement operator<< on Value...
79 virtual void print(std::ostream &O) const = 0;
80 void print(std::ostream *O) const { if (O) print(*O); }
82 /// All values are typed, get the type of this value.
84 inline const Type *getType() const { return Ty; }
86 // All values can potentially be named...
87 inline bool hasName() const { return !Name.empty(); }
88 inline const std::string &getName() const { return Name; }
90 void setName(const std::string &name);
92 /// replaceAllUsesWith - Go through the uses list for this definition and make
93 /// each use point to "V" instead of "this". After this completes, 'this's
94 /// use list is guaranteed to be empty.
96 void replaceAllUsesWith(Value *V);
98 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous.
99 // Only use when in type resolution situations!
100 void uncheckedReplaceAllUsesWith(Value *V);
102 //----------------------------------------------------------------------
103 // Methods for handling the vector of uses of this Value.
105 typedef value_use_iterator<User> use_iterator;
106 typedef value_use_iterator<const User> use_const_iterator;
108 bool use_empty() const { return UseList == 0; }
109 use_iterator use_begin() { return use_iterator(UseList); }
110 use_const_iterator use_begin() const { return use_const_iterator(UseList); }
111 use_iterator use_end() { return use_iterator(0); }
112 use_const_iterator use_end() const { return use_const_iterator(0); }
113 User *use_back() { return *use_begin(); }
114 const User *use_back() const { return *use_begin(); }
116 /// hasOneUse - Return true if there is exactly one user of this value. This
117 /// is specialized because it is a common request and does not require
118 /// traversing the whole use list.
120 bool hasOneUse() const {
121 use_const_iterator I = use_begin(), E = use_end();
122 if (I == E) return false;
126 /// hasNUses - Return true if this Value has exactly N users.
128 bool hasNUses(unsigned N) const;
130 /// hasNUsesOrMore - Return true if this value has N users or more. This is
131 /// logically equivalent to getNumUses() >= N.
133 bool hasNUsesOrMore(unsigned N) const;
135 /// getNumUses - This method computes the number of uses of this Value. This
136 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses
137 /// to check for specific values.
138 unsigned getNumUses() const;
140 /// addUse/killUse - These two methods should only be used by the Use class.
142 void addUse(Use &U) { U.addToList(&UseList); }
144 /// An enumeration for keeping track of the concrete subclass of Value that
145 /// is actually instantiated. Values of this enumeration are kept in the
146 /// Value classes SubclassID field. They are used for concrete type
149 ArgumentVal, // This is an instance of Argument
150 BasicBlockVal, // This is an instance of BasicBlock
151 FunctionVal, // This is an instance of Function
152 GlobalVariableVal, // This is an instance of GlobalVariable
153 UndefValueVal, // This is an instance of UndefValue
154 ConstantExprVal, // This is an instance of ConstantExpr
155 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull
156 ConstantIntVal, // This is an instance of ConstantInt
157 ConstantFPVal, // This is an instance of ConstantFP
158 ConstantArrayVal, // This is an instance of ConstantArray
159 ConstantStructVal, // This is an instance of ConstantStruct
160 ConstantPackedVal, // This is an instance of ConstantPacked
161 ConstantPointerNullVal, // This is an instance of ConstantPointerNull
162 InlineAsmVal, // This is an instance of InlineAsm
163 InstructionVal, // This is an instance of Instruction
166 ConstantFirstVal = FunctionVal,
167 ConstantLastVal = ConstantPointerNullVal
170 /// getValueType - Return an ID for the concrete type of this object. This is
171 /// used to implement the classof checks. This should not be used for any
172 /// other purpose, as the values may change as LLVM evolves. Also, note that
173 /// starting with the InstructionVal value, the value stored is actually the
174 /// Instruction opcode, so there are more than just these values possible here
175 /// (and Instruction must be last).
177 unsigned getValueType() const {
181 // Methods for support type inquiry through isa, cast, and dyn_cast:
182 static inline bool classof(const Value *) {
183 return true; // Values are always values.
186 /// getRawType - This should only be used to implement the vmcore library.
188 const Type *getRawType() const { return Ty.getRawType(); }
191 inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
196 void Use::init(Value *v, User *user) {
199 if (Val) Val->addUse(*this);
203 if (Val) removeFromList();
206 void Use::set(Value *V) {
207 if (Val) removeFromList();
209 if (V) V->addUse(*this);
213 // isa - Provide some specializations of isa so that we don't have to include
214 // the subtype header files to test to see if the value is a subclass...
216 template <> inline bool isa_impl<Constant, Value>(const Value &Val) {
217 return Val.getValueType() >= Value::ConstantFirstVal &&
218 Val.getValueType() <= Value::ConstantLastVal;
220 template <> inline bool isa_impl<Argument, Value>(const Value &Val) {
221 return Val.getValueType() == Value::ArgumentVal;
223 template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) {
224 return Val.getValueType() == Value::InlineAsmVal;
226 template <> inline bool isa_impl<Instruction, Value>(const Value &Val) {
227 return Val.getValueType() >= Value::InstructionVal;
229 template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) {
230 return Val.getValueType() == Value::BasicBlockVal;
232 template <> inline bool isa_impl<Function, Value>(const Value &Val) {
233 return Val.getValueType() == Value::FunctionVal;
235 template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) {
236 return Val.getValueType() == Value::GlobalVariableVal;
238 template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) {
239 return isa<GlobalVariable>(Val) || isa<Function>(Val);
242 } // End llvm namespace