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//===-- llvm/Value.h - Definition of the Value class ------------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file declares the Value class.
#include "llvm-c/Core.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/IR/Use.h"
#include "llvm/Support/CBindingWrapping.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
namespace llvm {
class APInt;
class Argument;
class AssemblyAnnotationWriter;
class BasicBlock;
class Constant;
class DataLayout;
class Function;
class GlobalAlias;
class GlobalObject;
class GlobalValue;
class GlobalVariable;
class InlineAsm;
class Instruction;
class LLVMContext;
class MDNode;
class Module;
class StringRef;
class Twine;
class Type;
class ValueHandleBase;
class ValueSymbolTable;
class raw_ostream;
template<typename ValueTy> class StringMapEntry;
typedef StringMapEntry<Value*> ValueName;
// Value Class
/// This is a very important LLVM class. It is the base class of all values
/// computed by a program that may be used as operands to other values. Value is
/// the super class of other important classes such as Instruction and Function.
/// All Values have a Type. Type is not a subclass of Value. Some values can
/// have a name and they belong to some Module. Setting the name on the Value
/// automatically updates the module's symbol table.
/// Every value has a "use list" that keeps track of which other Values are
/// using this Value. A Value can also have an arbitrary number of ValueHandle
/// objects that watch it and listen to RAUW and Destroy events. See
/// llvm/IR/ValueHandle.h for details.
/// @brief LLVM Value Representation
class Value {
Type *VTy;
Use *UseList;
friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name.
friend class ValueHandleBase;
ValueName *Name;
const unsigned char SubclassID; // Subclass identifier (for isa/dyn_cast)
unsigned char HasValueHandle : 1; // Has a ValueHandle pointing to this?
/// SubclassOptionalData - This member is similar to SubclassData, however it
/// is for holding information which may be used to aid optimization, but
/// which may be cleared to zero without affecting conservative
/// interpretation.
unsigned char SubclassOptionalData : 7;
/// 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;
template <typename UseT> // UseT == 'Use' or 'const Use'
class use_iterator_impl
: public std::iterator<std::forward_iterator_tag, UseT *, ptrdiff_t> {
typedef std::iterator<std::forward_iterator_tag, UseT *, ptrdiff_t> super;
UseT *U;
explicit use_iterator_impl(UseT *u) : U(u) {}
friend class Value;
typedef typename super::reference reference;
typedef typename super::pointer pointer;
use_iterator_impl() : U() {}
bool operator==(const use_iterator_impl &x) const { return U == x.U; }
bool operator!=(const use_iterator_impl &x) const { return !operator==(x); }
use_iterator_impl &operator++() { // Preincrement
assert(U && "Cannot increment end iterator!");
U = U->getNext();
return *this;
use_iterator_impl operator++(int) { // Postincrement
auto tmp = *this;
return tmp;
UseT &operator*() const {
assert(U && "Cannot dereference end iterator!");
return *U;
UseT *operator->() const { return &operator*(); }
operator use_iterator_impl<const UseT>() const {
return use_iterator_impl<const UseT>(U);
template <typename UserTy> // UserTy == 'User' or 'const User'
class user_iterator_impl
: public std::iterator<std::forward_iterator_tag, UserTy *, ptrdiff_t> {
typedef std::iterator<std::forward_iterator_tag, UserTy *, ptrdiff_t> super;
use_iterator_impl<Use> UI;
explicit user_iterator_impl(Use *U) : UI(U) {}
friend class Value;
typedef typename super::reference reference;
typedef typename super::pointer pointer;
user_iterator_impl() {}
bool operator==(const user_iterator_impl &x) const { return UI == x.UI; }
bool operator!=(const user_iterator_impl &x) const { return !operator==(x); }
/// \brief Returns true if this iterator is equal to user_end() on the value.
bool atEnd() const { return *this == user_iterator_impl(); }
user_iterator_impl &operator++() { // Preincrement
return *this;
user_iterator_impl operator++(int) { // Postincrement
auto tmp = *this;
return tmp;
// Retrieve a pointer to the current User.
UserTy *operator*() const {
return UI->getUser();
UserTy *operator->() const { return operator*(); }
operator user_iterator_impl<const UserTy>() const {
return user_iterator_impl<const UserTy>(*UI);
Use &getUse() const { return *UI; }
/// \brief Return the operand # of this use in its User.
/// FIXME: Replace all callers with a direct call to Use::getOperandNo.
unsigned getOperandNo() const { return UI->getOperandNo(); }
void operator=(const Value &) LLVM_DELETED_FUNCTION;
Value(const Value &) LLVM_DELETED_FUNCTION;
Value(Type *Ty, unsigned scid);
virtual ~Value();
/// dump - Support for debugging, callable in GDB: V->dump()
void dump() const;
/// print - Implement operator<< on Value.
void print(raw_ostream &O) const;
/// \brief Print the name of this Value out to the specified raw_ostream.
/// This is useful when you just want to print 'int %reg126', not the
/// instruction that generated it. If you specify a Module for context, then
/// even constanst get pretty-printed; for example, the type of a null
/// pointer is printed symbolically.
void printAsOperand(raw_ostream &O, bool PrintType = true,
const Module *M = nullptr) const;
/// All values are typed, get the type of this value.
Type *getType() const { return VTy; }
/// All values hold a context through their type.
LLVMContext &getContext() const;
// All values can potentially be named.
bool hasName() const { return Name != nullptr && SubclassID != MDStringVal; }
ValueName *getValueName() const { return Name; }
void setValueName(ValueName *VN) { Name = VN; }
/// getName() - Return a constant reference to the value's name. This is cheap
/// and guaranteed to return the same reference as long as the value is not
/// modified.
StringRef getName() const;
/// setName() - Change the name of the value, choosing a new unique name if
/// the provided name is taken.
/// \param Name The new name; or "" if the value's name should be removed.
void setName(const Twine &Name);
/// takeName - transfer the name from V to this value, setting V's name to
/// empty. It is an error to call V->takeName(V).
void takeName(Value *V);
/// 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);
// Methods for handling the chain of uses of this Value.
bool use_empty() const { return UseList == nullptr; }
typedef use_iterator_impl<Use> use_iterator;
typedef use_iterator_impl<const Use> const_use_iterator;
use_iterator use_begin() { return use_iterator(UseList); }
const_use_iterator use_begin() const { return const_use_iterator(UseList); }
use_iterator use_end() { return use_iterator(); }
const_use_iterator use_end() const { return const_use_iterator(); }
iterator_range<use_iterator> uses() {
return iterator_range<use_iterator>(use_begin(), use_end());
iterator_range<const_use_iterator> uses() const {
return iterator_range<const_use_iterator>(use_begin(), use_end());
typedef user_iterator_impl<User> user_iterator;
typedef user_iterator_impl<const User> const_user_iterator;
user_iterator user_begin() { return user_iterator(UseList); }
const_user_iterator user_begin() const { return const_user_iterator(UseList); }
user_iterator user_end() { return user_iterator(); }
const_user_iterator user_end() const { return const_user_iterator(); }
User *user_back() { return *user_begin(); }
const User *user_back() const { return *user_begin(); }
iterator_range<user_iterator> users() {
return iterator_range<user_iterator>(user_begin(), user_end());
iterator_range<const_user_iterator> users() const {
return iterator_range<const_user_iterator>(user_begin(), user_end());
/// 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 {
const_use_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;
bool isUsedInBasicBlock(const BasicBlock *BB) const;
/// getNumUses - This method computes the number of uses of this Value. This
/// is a linear time operation. Use hasOneUse, hasNUses, or hasNUsesOrMore
/// to check for specific values.
unsigned getNumUses() const;
/// addUse - This method should only be used by the Use class.
void addUse(Use &U) { U.addToList(&UseList); }
/// An enumeration for keeping track of the concrete subclass of Value that
/// is actually instantiated. Values of this enumeration are kept in the
/// Value classes SubclassID field. They are used for concrete type
/// identification.
enum ValueTy {
ArgumentVal, // This is an instance of Argument
BasicBlockVal, // This is an instance of BasicBlock
FunctionVal, // This is an instance of Function
GlobalAliasVal, // This is an instance of GlobalAlias
GlobalVariableVal, // This is an instance of GlobalVariable
UndefValueVal, // This is an instance of UndefValue
BlockAddressVal, // This is an instance of BlockAddress
ConstantExprVal, // This is an instance of ConstantExpr
ConstantAggregateZeroVal, // This is an instance of ConstantAggregateZero
ConstantDataArrayVal, // This is an instance of ConstantDataArray
ConstantDataVectorVal, // This is an instance of ConstantDataVector
ConstantIntVal, // This is an instance of ConstantInt
ConstantFPVal, // This is an instance of ConstantFP
ConstantArrayVal, // This is an instance of ConstantArray
ConstantStructVal, // This is an instance of ConstantStruct
ConstantVectorVal, // This is an instance of ConstantVector
ConstantPointerNullVal, // This is an instance of ConstantPointerNull
MDNodeVal, // This is an instance of MDNode
MDStringVal, // This is an instance of MDString
InlineAsmVal, // This is an instance of InlineAsm
InstructionVal, // This is an instance of Instruction
// Enum values starting at InstructionVal are used for Instructions;
// don't add new values here!
// Markers:
ConstantFirstVal = FunctionVal,
ConstantLastVal = ConstantPointerNullVal
/// getValueID - 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
/// for instructions, the Instruction's opcode is added to InstructionVal. So
/// this means three things:
/// # there is no value with code InstructionVal (no opcode==0).
/// # there are more possible values for the value type than in ValueTy enum.
/// # the InstructionVal enumerator must be the highest valued enumerator in
/// the ValueTy enum.
unsigned getValueID() const {
return SubclassID;
/// getRawSubclassOptionalData - Return the raw optional flags value
/// contained in this value. This should only be used when testing two
/// Values for equivalence.
unsigned getRawSubclassOptionalData() const {
return SubclassOptionalData;
/// clearSubclassOptionalData - Clear the optional flags contained in
/// this value.
void clearSubclassOptionalData() {
SubclassOptionalData = 0;
/// hasSameSubclassOptionalData - Test whether the optional flags contained
/// in this value are equal to the optional flags in the given value.
bool hasSameSubclassOptionalData(const Value *V) const {
return SubclassOptionalData == V->SubclassOptionalData;
/// intersectOptionalDataWith - Clear any optional flags in this value
/// that are not also set in the given value.
void intersectOptionalDataWith(const Value *V) {
SubclassOptionalData &= V->SubclassOptionalData;
/// hasValueHandle - Return true if there is a value handle associated with
/// this value.
bool hasValueHandle() const { return HasValueHandle; }
/// \brief Strips off any unneeded pointer casts, all-zero GEPs and aliases
/// from the specified value, returning the original uncasted value.
/// If this is called on a non-pointer value, it returns 'this'.
Value *stripPointerCasts();
const Value *stripPointerCasts() const {
return const_cast<Value*>(this)->stripPointerCasts();
/// \brief Strips off any unneeded pointer casts and all-zero GEPs from the
/// specified value, returning the original uncasted value.
/// If this is called on a non-pointer value, it returns 'this'.
Value *stripPointerCastsNoFollowAliases();
const Value *stripPointerCastsNoFollowAliases() const {
return const_cast<Value*>(this)->stripPointerCastsNoFollowAliases();
/// \brief Strips off unneeded pointer casts and all-constant GEPs from the
/// specified value, returning the original pointer value.
/// If this is called on a non-pointer value, it returns 'this'.
Value *stripInBoundsConstantOffsets();
const Value *stripInBoundsConstantOffsets() const {
return const_cast<Value*>(this)->stripInBoundsConstantOffsets();
/// \brief Strips like \c stripInBoundsConstantOffsets but also accumulates
/// the constant offset stripped.
/// Stores the resulting constant offset stripped into the APInt provided.
/// The provided APInt will be extended or truncated as needed to be the
/// correct bitwidth for an offset of this pointer type.
/// If this is called on a non-pointer value, it returns 'this'.
Value *stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
APInt &Offset);
const Value *stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
APInt &Offset) const {
return const_cast<Value *>(this)
->stripAndAccumulateInBoundsConstantOffsets(DL, Offset);
/// \brief Strips off unneeded pointer casts and any in-bounds offsets from
/// the specified value, returning the original pointer value.
/// If this is called on a non-pointer value, it returns 'this'.
Value *stripInBoundsOffsets();
const Value *stripInBoundsOffsets() const {
return const_cast<Value*>(this)->stripInBoundsOffsets();
/// isDereferenceablePointer - Test if this value is always a pointer to
/// allocated and suitably aligned memory for a simple load or store.
bool isDereferenceablePointer(const DataLayout *DL = nullptr) const;
/// DoPHITranslation - If this value is a PHI node with CurBB as its parent,
/// return the value in the PHI node corresponding to PredBB. If not, return
/// ourself. This is useful if you want to know the value something has in a
/// predecessor block.
Value *DoPHITranslation(const BasicBlock *CurBB, const BasicBlock *PredBB);
const Value *DoPHITranslation(const BasicBlock *CurBB,
const BasicBlock *PredBB) const{
return const_cast<Value*>(this)->DoPHITranslation(CurBB, PredBB);
/// MaximumAlignment - This is the greatest alignment value supported by
/// load, store, and alloca instructions, and global values.
static const unsigned MaximumAlignment = 1u << 29;
/// mutateType - Mutate the type of this Value to be of the specified type.
/// Note that this is an extremely dangerous operation which can create
/// completely invalid IR very easily. It is strongly recommended that you
/// recreate IR objects with the right types instead of mutating them in
/// place.
void mutateType(Type *Ty) {
VTy = Ty;
unsigned short getSubclassDataFromValue() const { return SubclassData; }
void setValueSubclassData(unsigned short D) { SubclassData = D; }
inline raw_ostream &operator<<(raw_ostream &OS, const Value &V) {
return OS;
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 <> struct isa_impl<Constant, Value> {
static inline bool doit(const Value &Val) {
return Val.getValueID() >= Value::ConstantFirstVal &&
Val.getValueID() <= Value::ConstantLastVal;
template <> struct isa_impl<Argument, Value> {
static inline bool doit (const Value &Val) {
return Val.getValueID() == Value::ArgumentVal;
template <> struct isa_impl<InlineAsm, Value> {
static inline bool doit(const Value &Val) {
return Val.getValueID() == Value::InlineAsmVal;
template <> struct isa_impl<Instruction, Value> {
static inline bool doit(const Value &Val) {
return Val.getValueID() >= Value::InstructionVal;
template <> struct isa_impl<BasicBlock, Value> {
static inline bool doit(const Value &Val) {
return Val.getValueID() == Value::BasicBlockVal;
template <> struct isa_impl<Function, Value> {
static inline bool doit(const Value &Val) {
return Val.getValueID() == Value::FunctionVal;
template <> struct isa_impl<GlobalVariable, Value> {
static inline bool doit(const Value &Val) {
return Val.getValueID() == Value::GlobalVariableVal;
template <> struct isa_impl<GlobalAlias, Value> {
static inline bool doit(const Value &Val) {
return Val.getValueID() == Value::GlobalAliasVal;
template <> struct isa_impl<GlobalValue, Value> {
static inline bool doit(const Value &Val) {
return isa<GlobalObject>(Val) || isa<GlobalAlias>(Val);
template <> struct isa_impl<GlobalObject, Value> {
static inline bool doit(const Value &Val) {
return isa<GlobalVariable>(Val) || isa<Function>(Val);
template <> struct isa_impl<MDNode, Value> {
static inline bool doit(const Value &Val) {
return Val.getValueID() == Value::MDNodeVal;
// Value* is only 4-byte aligned.
class PointerLikeTypeTraits<Value*> {
typedef Value* PT;
static inline void *getAsVoidPointer(PT P) { return P; }
static inline PT getFromVoidPointer(void *P) {
return static_cast<PT>(P);
enum { NumLowBitsAvailable = 2 };
// Create wrappers for C Binding types (see CBindingWrapping.h).
/* Specialized opaque value conversions.
inline Value **unwrap(LLVMValueRef *Vals) {
return reinterpret_cast<Value**>(Vals);
template<typename T>
inline T **unwrap(LLVMValueRef *Vals, unsigned Length) {
#ifdef DEBUG
for (LLVMValueRef *I = Vals, *E = Vals + Length; I != E; ++I)
return reinterpret_cast<T**>(Vals);
inline LLVMValueRef *wrap(const Value **Vals) {
return reinterpret_cast<LLVMValueRef*>(const_cast<Value**>(Vals));
} // End llvm namespace