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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.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_VALUE_H
#define LLVM_VALUE_H
#include "llvm/AbstractTypeUser.h"
#include "llvm/Use.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.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 GlobalAlias;
class InlineAsm;
class ValueSymbolTable;
class TypeSymbolTable;
template<typename ValueTy> class StringMapEntry;
template <typename ValueTy = Value>
class AssertingVH;
typedef StringMapEntry<Value*> ValueName;
class raw_ostream;
class AssemblyAnnotationWriter;
class ValueHandleBase;
class LLVMContext;
//===----------------------------------------------------------------------===//
// 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. All types can have
/// a name and they should 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/Support/ValueHandle.h for details.
///
/// @brief LLVM Value Representation
class Value {
const unsigned char SubclassID; // Subclass identifier (for isa/dyn_cast)
unsigned char HasValueHandle : 1; // Has a ValueHandle pointing to this?
protected:
/// 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;
private:
PATypeHolder VTy;
Use *UseList;
friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name.
friend class SymbolTable; // Allow SymbolTable to directly poke Name.
friend class ValueHandleBase;
ValueName *Name;
void operator=(const Value &); // Do not implement
Value(const Value &); // Do not implement
public:
Value(const Type *Ty, unsigned scid);
virtual ~Value();
/// dump - Support for debugging, callable in GDB: V->dump()
//
virtual void dump() const;
/// print - Implement operator<< on Value.
///
void print(raw_ostream &O, AssemblyAnnotationWriter *AAW = 0) const;
/// All values are typed, get the type of this value.
///
inline const Type *getType() const { return VTy; }
/// All values hold a context through their type.
LLVMContext &getContext() const;
// All values can potentially be named...
inline bool hasName() const { return Name != 0; }
ValueName *getValueName() const { return Name; }
/// 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.
///
/// This is currently guaranteed to return a StringRef for which data() points
/// to a valid null terminated string. The use of StringRef.data() is
/// deprecated here, however, and clients should not rely on it. If such
/// behavior is needed, clients should use expensive getNameStr(), or switch
/// to an interface that does not depend on null termination.
StringRef getName() const;
/// getNameStr() - Return the name of the specified value, *constructing a
/// string* to hold it. This is guaranteed to construct a string and is very
/// expensive, clients should use getName() unless necessary.
std::string getNameStr() const;
/// setName() - Change the name of the value, choosing a new unique name if
/// the provided name is taken.
///
/// \arg 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);
// uncheckedReplaceAllUsesWith - Just like replaceAllUsesWith but dangerous.
// Only use when in type resolution situations!
void uncheckedReplaceAllUsesWith(Value *V);
/// clearOptionalData - Clear any optional optimization data from this Value.
/// Transformation passes must call this method whenever changing the IR
/// in a way that would affect the values produced by this Value, unless
/// it takes special care to ensure correctness in some other way.
void clearOptionalData() { SubclassOptionalData = 0; }
//----------------------------------------------------------------------
// Methods for handling the chain 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;
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 hasMoreThanNUses
/// 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
ConstantExprVal, // This is an instance of ConstantExpr
ConstantAggregateZeroVal, // This is an instance of ConstantAggregateNull
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
NamedMDNodeVal, // This is an instance of NamedMDNode
InlineAsmVal, // This is an instance of InlineAsm
PseudoSourceValueVal, // This is an instance of PseudoSourceValue
InstructionVal, // This is an instance of Instruction
// 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;
}
// Methods for support type inquiry through isa, cast, and dyn_cast:
static inline bool classof(const Value *) {
return true; // Values are always values.
}
/// getRawType - This should only be used to implement the vmcore library.
///
const Type *getRawType() const { return VTy.getRawType(); }
/// stripPointerCasts - This method strips off any unneeded pointer
/// casts from the specified value, returning the original uncasted value.
/// Note that the returned value has pointer type if the specified value does.
Value *stripPointerCasts();
const Value *stripPointerCasts() const {
return const_cast<Value*>(this)->stripPointerCasts();
}
/// getUnderlyingObject - This method strips off any GEP address adjustments
/// and pointer casts from the specified value, returning the original object
/// being addressed. Note that the returned value has pointer type if the
/// specified value does.
Value *getUnderlyingObject();
const Value *getUnderlyingObject() const {
return const_cast<Value*>(this)->getUnderlyingObject();
}
/// 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);
}
};
inline raw_ostream &operator<<(raw_ostream &OS, const Value &V) {
V.print(OS);
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 <> inline bool isa_impl<Constant, Value>(const Value &Val) {
return Val.getValueID() >= Value::ConstantFirstVal &&
Val.getValueID() <= Value::ConstantLastVal;
}
template <> inline bool isa_impl<Argument, Value>(const Value &Val) {
return Val.getValueID() == Value::ArgumentVal;
}
template <> inline bool isa_impl<InlineAsm, Value>(const Value &Val) {
return Val.getValueID() == Value::InlineAsmVal;
}
template <> inline bool isa_impl<Instruction, Value>(const Value &Val) {
return Val.getValueID() >= Value::InstructionVal;
}
template <> inline bool isa_impl<BasicBlock, Value>(const Value &Val) {
return Val.getValueID() == Value::BasicBlockVal;
}
template <> inline bool isa_impl<Function, Value>(const Value &Val) {
return Val.getValueID() == Value::FunctionVal;
}
template <> inline bool isa_impl<GlobalVariable, Value>(const Value &Val) {
return Val.getValueID() == Value::GlobalVariableVal;
}
template <> inline bool isa_impl<GlobalAlias, Value>(const Value &Val) {
return Val.getValueID() == Value::GlobalAliasVal;
}
template <> inline bool isa_impl<GlobalValue, Value>(const Value &Val) {
return isa<GlobalVariable>(Val) || isa<Function>(Val) ||
isa<GlobalAlias>(Val);
}
// Value* is only 4-byte aligned.
template<>
class PointerLikeTypeTraits<Value*> {
typedef Value* PT;
public:
static inline void *getAsVoidPointer(PT P) { return P; }
static inline PT getFromVoidPointer(void *P) {
return static_cast<PT>(P);
}
enum { NumLowBitsAvailable = 2 };
};
} // End llvm namespace
#endif
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