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"
35 //===----------------------------------------------------------------------===//
37 //===----------------------------------------------------------------------===//
39 /// This is a very important LLVM class. It is the base class of all values
40 /// computed by a program that may be used as operands to other values. Value is
41 /// the super class of other important classes such as Instruction and Function.
42 /// All Values have a Type. Type is not a subclass of Value. All types can have
43 /// a name and they should belong to some Module. Setting the name on the Value
44 /// automatically update's the module's symbol table.
46 /// Every value has a "use list" that keeps track of which other Values are
48 /// @brief LLVM Value Representation
50 unsigned short SubclassID; // Subclass identifier (for isa/dyn_cast)
52 /// SubclassData - This member is defined by this class, but is not used for
53 /// anything. Subclasses can use it to hold whatever state they find useful.
54 /// This field is initialized to zero by the ctor.
55 unsigned short SubclassData;
60 friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name.
61 friend class SymbolTable; // Allow SymbolTable to directly poke Name.
64 void operator=(const Value &); // Do not implement
65 Value(const Value &); // Do not implement
68 Value(const Type *Ty, unsigned scid, const std::string &name = "");
71 /// dump - Support for debugging, callable in GDB: V->dump()
73 virtual void dump() const;
75 /// print - Implement operator<< on Value...
77 virtual void print(std::ostream &O) const = 0;
79 /// All values are typed, get the type of this value.
81 inline const Type *getType() const { return Ty; }
83 // All values can potentially be named...
84 inline bool hasName() const { return !Name.empty(); }
85 inline const std::string &getName() const { return Name; }
87 void setName(const std::string &name);
89 /// replaceAllUsesWith - Go through the uses list for this definition and make
90 /// each use point to "V" instead of "this". After this completes, 'this's
91 /// use list is guaranteed to be empty.
93 void replaceAllUsesWith(Value *V);
95 // uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous.
96 // Only use when in type resolution situations!
97 void uncheckedReplaceAllUsesWith(Value *V);
99 //----------------------------------------------------------------------
100 // Methods for handling the vector of uses of this Value.
102 typedef value_use_iterator<User> use_iterator;
103 typedef value_use_iterator<const User> use_const_iterator;
105 bool use_empty() const { return UseList == 0; }
106 use_iterator use_begin() { return use_iterator(UseList); }
107 use_const_iterator use_begin() const { return use_const_iterator(UseList); }
108 use_iterator use_end() { return use_iterator(0); }
109 use_const_iterator use_end() const { return use_const_iterator(0); }
110 User *use_back() { return *use_begin(); }
111 const User *use_back() const { return *use_begin(); }
113 /// hasOneUse - Return true if there is exactly one user of this value. This
114 /// is specialized because it is a common request and does not require
115 /// traversing the whole use list.
117 bool hasOneUse() const {
118 use_const_iterator I = use_begin(), E = use_end();
119 if (I == E) return false;
123 /// hasNUses - Return true if this Value has exactly N users.
125 bool hasNUses(unsigned N) const;
127 /// hasNUsesOrMore - Return true if this value has N users or more. This is
128 /// logically equivalent to getNumUses() >= N.
130 bool hasNUsesOrMore(unsigned N) const;
132 /// getNumUses - This method computes the number of uses of this Value. This
133 /// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses
134 /// to check for specific values.
135 unsigned getNumUses() const;
137 /// addUse/killUse - These two methods should only be used by the Use class.
139 void addUse(Use &U) { U.addToList(&UseList); }
141 /// An enumeration for keeping track of the concrete subclass of Value that
142 /// is actually instantiated. Values of this enumeration are kept in the
143 /// Value classes SubclassID field. They are used for concrete type
146 ArgumentVal, // This is an instance of Argument
147 BasicBlockVal, // This is an instance of BasicBlock
148 FunctionVal, // This is an instance of Function
149 GlobalVariableVal, // This is an instance of GlobalVariable
150 UndefValueVal, // This is an instance of UndefValue
151 ConstantExprVal, // This is an instance of ConstantExpr
152 ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull
153 ConstantBoolVal, // This is an instance of ConstantBool
154 ConstantSIntVal, // This is an instance of ConstantSInt
155 ConstantUIntVal, // This is an instance of ConstantUInt
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 /// FIXME: this is a gross hack, needed by another gross hack. Eliminate!
191 void setValueType(unsigned short VT) { SubclassID = VT; }
192 friend class Instruction;
195 inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
200 void Use::init(Value *v, User *user) {
203 if (Val) Val->addUse(*this);
207 if (Val) removeFromList();
210 void Use::set(Value *V) {
211 if (Val) removeFromList();
213 if (V) V->addUse(*this);
217 // isa - Provide some specializations of isa so that we don't have to include
218 // the subtype header files to test to see if the value is a subclass...
220 template <> inline bool isa_impl<Constant, Value>(const Value &Val) {
221 return Val.getValueType() >= Value::ConstantFirstVal &&
222 Val.getValueType() <= Value::ConstantLastVal;
224 template <> inline bool isa_impl<Argument, Value>(const Value &Val) {
225 return Val.getValueType() == Value::ArgumentVal;
227 template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) {
228 return Val.getValueType() == Value::InlineAsmVal;
230 template <> inline bool isa_impl<Instruction, Value>(const Value &Val) {
231 return Val.getValueType() >= Value::InstructionVal;
233 template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) {
234 return Val.getValueType() == Value::BasicBlockVal;
236 template <> inline bool isa_impl<Function, Value>(const Value &Val) {
237 return Val.getValueType() == Value::FunctionVal;
239 template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) {
240 return Val.getValueType() == Value::GlobalVariableVal;
242 template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) {
243 return isa<GlobalVariable>(Val) || isa<Function>(Val);
246 } // End llvm namespace