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//===-- llvm/Value.h - Definition of the Value class ------------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
// This file defines the very important Value class. This is subclassed by a
// bunch of other important classes, like Instruction, Function, Type, etc...
// This file also defines the Use<> template for users of value.
#ifndef LLVM_VALUE_H
#define LLVM_VALUE_H
#include "llvm/AbstractTypeUser.h"
#include "llvm/Use.h"
#include "llvm/Support/Casting.h"
#include <string>
namespace llvm {
class Constant;
class Argument;
class Instruction;
class BasicBlock;
class GlobalValue;
class Function;
class GlobalVariable;
class SymbolTable;
// Value Class
/// Value - The base class of all values computed by a program that may be used
/// as operands to other values.
class Value {
unsigned short SubclassID; // Subclass identifier (for isa/dyn_cast)
/// SubclassData - This member is defined by this class, but is not used for
/// anything. Subclasses can use it to hold whatever state they find useful.
/// This field is initialized to zero by the ctor.
unsigned short SubclassData;
PATypeHolder Ty;
Use *UseList;
friend class SymbolTable; // Allow SymbolTable to directly poke Name.
std::string Name;
void operator=(const Value &); // Do not implement
Value(const Value &); // Do not implement
Value(const Type *Ty, unsigned scid, const std::string &name = "");
virtual ~Value();
/// dump - Support for debugging, callable in GDB: V->dump()
virtual void dump() const;
/// print - Implement operator<< on Value...
virtual void print(std::ostream &O) const = 0;
/// All values are typed, get the type of this value.
inline const Type *getType() const { return Ty; }
// All values can potentially be named...
inline bool hasName() const { return !Name.empty(); }
inline const std::string &getName() const { return Name; }
void setName(const std::string &name);
/// replaceAllUsesWith - Go through the uses list for this definition and make
/// each use point to "V" instead of "this". After this completes, 'this's
/// use list is guaranteed to be empty.
void replaceAllUsesWith(Value *V);
// uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous.
// Only use when in type resolution situations!
void uncheckedReplaceAllUsesWith(Value *V);
// Methods for handling the vector of uses of this Value.
typedef value_use_iterator<User> use_iterator;
typedef value_use_iterator<const User> use_const_iterator;
bool use_empty() const { return UseList == 0; }
use_iterator use_begin() { return use_iterator(UseList); }
use_const_iterator use_begin() const { return use_const_iterator(UseList); }
use_iterator use_end() { return use_iterator(0); }
use_const_iterator use_end() const { return use_const_iterator(0); }
User *use_back() { return *use_begin(); }
const User *use_back() const { return *use_begin(); }
/// hasOneUse - Return true if there is exactly one user of this value. This
/// is specialized because it is a common request and does not require
/// traversing the whole use list.
bool hasOneUse() const {
use_const_iterator I = use_begin(), E = use_end();
if (I == E) return false;
return ++I == E;
/// hasNUses - Return true if this Value has exactly N users.
bool hasNUses(unsigned N) const;
/// hasNUsesOrMore - Return true if this value has N users or more. This is
/// logically equivalent to getNumUses() >= N.
bool hasNUsesOrMore(unsigned N) const;
/// getNumUses - This method computes the number of uses of this Value. This
/// is a linear time operation. Use hasOneUse, hasNUses, or hasMoreThanNUses
/// to check for specific values.
unsigned getNumUses() const;
/// addUse/killUse - These two methods should only be used by the Use class.
void addUse(Use &U) { U.addToList(&UseList); }
/// getValueType - Return an ID for the concrete type of this object. This is
/// used to implement the classof checks. This should not be used for any
/// other purpose, as the values may change as LLVM evolves. Also, note that
/// starting with the InstructionVal value, the value stored is actually the
/// Instruction opcode, so there are more than just these values possible here
/// (and Instruction must be last).
enum ValueTy {
ArgumentVal, // This is an instance of Argument
BasicBlockVal, // This is an instance of BasicBlock
FunctionVal, // This is an instance of Function
GlobalVariableVal, // This is an instance of GlobalVariable
UndefValueVal, // This is an instance of UndefValue
ConstantExprVal, // This is an instance of ConstantExpr
ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull
ConstantBoolVal, // This is an instance of ConstantBool
ConstantSIntVal, // This is an instance of ConstantSInt
ConstantUIntVal, // This is an instance of ConstantUInt
ConstantFPVal, // This is an instance of ConstantFP
ConstantArrayVal, // This is an instance of ConstantArray
ConstantStructVal, // This is an instance of ConstantStruct
ConstantPackedVal, // This is an instance of ConstantPacked
ConstantPointerNullVal, // This is an instance of ConstantPointerNull
InstructionVal, // This is an instance of Instruction
// Markers:
ConstantFirstVal = FunctionVal,
ConstantLastVal = ConstantPointerNullVal
unsigned getValueType() const {
return SubclassID;
// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const Value *V) {
return true; // Values are always values.
/// getRawType - This should only be used to implement the vmcore library.
const Type *getRawType() const { return Ty.getRawType(); }
/// FIXME: this is a gross hack, needed by another gross hack. Eliminate!
void setValueType(unsigned VT) { SubclassID = VT; }
friend class Instruction;
inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
return OS;
void Use::init(Value *v, User *user) {
Val = v;
U = user;
if (Val) Val->addUse(*this);
Use::~Use() {
if (Val) removeFromList();
void Use::set(Value *V) {
if (Val) removeFromList();
Val = V;
if (V) V->addUse(*this);
// isa - Provide some specializations of isa so that we don't have to include
// the subtype header files to test to see if the value is a subclass...
template <> inline bool isa_impl<Constant, Value>(const Value &Val) {
return Val.getValueType() >= Value::ConstantFirstVal &&
Val.getValueType() <= Value::ConstantLastVal;
template <> inline bool isa_impl<Argument, Value>(const Value &Val) {
return Val.getValueType() == Value::ArgumentVal;
template <> inline bool isa_impl<Instruction, Value>(const Value &Val) {
return Val.getValueType() >= Value::InstructionVal;
template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) {
return Val.getValueType() == Value::BasicBlockVal;
template <> inline bool isa_impl<Function, Value>(const Value &Val) {
return Val.getValueType() == Value::FunctionVal;
template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) {
return Val.getValueType() == Value::GlobalVariableVal;
template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) {
return isa<GlobalVariable>(Val) || isa<Function>(Val);
} // End llvm namespace