llvm-6502/include/llvm/IR/Value.h
Ramkumar Ramachandra 2bcc808cf9 Standardize {pred,succ,use,user}_empty()
The functions {pred,succ,use,user}_{begin,end} exist, but many users
have to check *_begin() with *_end() by hand to determine if the
BasicBlock or User is empty. Fix this with a standard *_empty(),
demonstrating a few usecases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225760 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-13 03:46:47 +00:00

734 lines
25 KiB
C++

//===-- 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_IR_VALUE_H
#define LLVM_IR_VALUE_H
#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 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
//===----------------------------------------------------------------------===//
/// \brief LLVM Value Representation
///
/// 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.
class Value {
Type *VTy;
Use *UseList;
friend class ValueAsMetadata; // Allow access to NameAndIsUsedByMD.
friend class ValueHandleBase;
PointerIntPair<ValueName *, 1> NameAndIsUsedByMD;
const unsigned char SubclassID; // Subclass identifier (for isa/dyn_cast)
unsigned char HasValueHandle : 1; // Has a ValueHandle pointing to this?
protected:
/// \brief Hold subclass data that can be dropped.
///
/// 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;
private:
/// \brief Hold arbitrary subclass data.
///
/// 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;
protected:
/// \brief The number of operands in the subclass.
///
/// This member is defined by this class, but not used for anything.
/// Subclasses can use it to store their number of operands, if they have
/// any.
///
/// This is stored here to save space in User on 64-bit hosts. Since most
/// instances of Value have operands, 32-bit hosts aren't significantly
/// affected.
unsigned NumOperands;
private:
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;
public:
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;
++*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;
public:
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
++UI;
return *this;
}
user_iterator_impl operator++(int) { // Postincrement
auto tmp = *this;
++*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;
protected:
Value(Type *Ty, unsigned scid);
public:
virtual ~Value();
/// \brief Support for debugging, callable in GDB: V->dump()
void dump() const;
/// \brief 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;
/// \brief All values are typed, get the type of this value.
Type *getType() const { return VTy; }
/// \brief All values hold a context through their type.
LLVMContext &getContext() const;
// \brief All values can potentially be named.
bool hasName() const { return getValueName() != nullptr; }
ValueName *getValueName() const { return NameAndIsUsedByMD.getPointer(); }
void setValueName(ValueName *VN) { NameAndIsUsedByMD.setPointer(VN); }
private:
void destroyValueName();
public:
/// \brief 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;
/// \brief Change the name of the value.
///
/// Choose 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);
/// \brief Transfer the name from V to this value.
///
/// After taking V's name, sets V's name to empty.
///
/// \note It is an error to call V->takeName(V).
void takeName(Value *V);
/// \brief Change all uses of this to point to a new Value.
///
/// 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);
/// replaceUsesOutsideBlock - Go through the uses list for this definition and
/// make each use point to "V" instead of "this" when the use is outside the
/// block. 'This's use list is expected to have at least one element.
/// Unlike replaceAllUsesWith this function does not support basic block
/// values or constant users.
void replaceUsesOutsideBlock(Value *V, BasicBlock *BB);
//----------------------------------------------------------------------
// 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());
}
bool user_empty() const { return UseList == nullptr; }
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());
}
/// \brief 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;
}
/// \brief Return true if this Value has exactly N users.
bool hasNUses(unsigned N) const;
/// \brief Return true if this value has N users or more.
///
/// This is logically equivalent to getNumUses() >= N.
bool hasNUsesOrMore(unsigned N) const;
/// \brief Check if this value is used in the specified basic block.
bool isUsedInBasicBlock(const BasicBlock *BB) const;
/// \brief 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;
/// \brief This method should only be used by the Use class.
void addUse(Use &U) { U.addToList(&UseList); }
/// \brief Concrete subclass of this.
///
/// 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
MetadataAsValueVal, // This is an instance of MetadataAsValue
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
};
/// \brief 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;
}
/// \brief 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;
}
/// \brief Clear the optional flags contained in this value.
void clearSubclassOptionalData() {
SubclassOptionalData = 0;
}
/// \brief Check the optional flags for equality.
bool hasSameSubclassOptionalData(const Value *V) const {
return SubclassOptionalData == V->SubclassOptionalData;
}
/// \brief Clear any optional flags not set in the given Value.
void intersectOptionalDataWith(const Value *V) {
SubclassOptionalData &= V->SubclassOptionalData;
}
/// \brief Return true if there is a value handle associated with this value.
bool hasValueHandle() const { return HasValueHandle; }
/// \brief Return true if there is metadata referencing this value.
bool isUsedByMetadata() const { return NameAndIsUsedByMD.getInt(); }
/// \brief Strip off pointer casts, all-zero GEPs, and aliases.
///
/// Returns 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 Strip off pointer casts and all-zero GEPs.
///
/// Returns 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 Strip off pointer casts and all-constant inbounds GEPs.
///
/// Returns 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 Accumulate offsets from \a stripInBoundsConstantOffsets().
///
/// 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 Strip off pointer casts and inbounds GEPs.
///
/// Returns 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();
}
/// \brief Check if this is always a dereferenceable pointer.
///
/// 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;
/// \brief Translate PHI node to its predecessor from the given basic block.
///
/// 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);
}
/// \brief The maximum alignment for instructions.
///
/// This is the greatest alignment value supported by load, store, and alloca
/// instructions, and global values.
static const unsigned MaximumAlignment = 1u << 29;
/// \brief 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;
}
/// \brief Sort the use-list.
///
/// Sorts the Value's use-list by Cmp using a stable mergesort. Cmp is
/// expected to compare two \a Use references.
template <class Compare> void sortUseList(Compare Cmp);
/// \brief Reverse the use-list.
void reverseUseList();
private:
/// \brief Merge two lists together.
///
/// Merges \c L and \c R using \c Cmp. To enable stable sorts, always pushes
/// "equal" items from L before items from R.
///
/// \return the first element in the list.
///
/// \note Completely ignores \a Use::Prev (doesn't read, doesn't update).
template <class Compare>
static Use *mergeUseLists(Use *L, Use *R, Compare Cmp) {
Use *Merged;
mergeUseListsImpl(L, R, &Merged, Cmp);
return Merged;
}
/// \brief Tail-recursive helper for \a mergeUseLists().
///
/// \param[out] Next the first element in the list.
template <class Compare>
static void mergeUseListsImpl(Use *L, Use *R, Use **Next, Compare Cmp);
protected:
unsigned short getSubclassDataFromValue() const { return SubclassData; }
void setValueSubclassData(unsigned short D) { SubclassData = D; }
};
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);
}
template <class Compare> void Value::sortUseList(Compare Cmp) {
if (!UseList || !UseList->Next)
// No need to sort 0 or 1 uses.
return;
// Note: this function completely ignores Prev pointers until the end when
// they're fixed en masse.
// Create a binomial vector of sorted lists, visiting uses one at a time and
// merging lists as necessary.
const unsigned MaxSlots = 32;
Use *Slots[MaxSlots];
// Collect the first use, turning it into a single-item list.
Use *Next = UseList->Next;
UseList->Next = nullptr;
unsigned NumSlots = 1;
Slots[0] = UseList;
// Collect all but the last use.
while (Next->Next) {
Use *Current = Next;
Next = Current->Next;
// Turn Current into a single-item list.
Current->Next = nullptr;
// Save Current in the first available slot, merging on collisions.
unsigned I;
for (I = 0; I < NumSlots; ++I) {
if (!Slots[I])
break;
// Merge two lists, doubling the size of Current and emptying slot I.
//
// Since the uses in Slots[I] originally preceded those in Current, send
// Slots[I] in as the left parameter to maintain a stable sort.
Current = mergeUseLists(Slots[I], Current, Cmp);
Slots[I] = nullptr;
}
// Check if this is a new slot.
if (I == NumSlots) {
++NumSlots;
assert(NumSlots <= MaxSlots && "Use list bigger than 2^32");
}
// Found an open slot.
Slots[I] = Current;
}
// Merge all the lists together.
assert(Next && "Expected one more Use");
assert(!Next->Next && "Expected only one Use");
UseList = Next;
for (unsigned I = 0; I < NumSlots; ++I)
if (Slots[I])
// Since the uses in Slots[I] originally preceded those in UseList, send
// Slots[I] in as the left parameter to maintain a stable sort.
UseList = mergeUseLists(Slots[I], UseList, Cmp);
// Fix the Prev pointers.
for (Use *I = UseList, **Prev = &UseList; I; I = I->Next) {
I->setPrev(Prev);
Prev = &I->Next;
}
}
template <class Compare>
void Value::mergeUseListsImpl(Use *L, Use *R, Use **Next, Compare Cmp) {
if (!L) {
*Next = R;
return;
}
if (!R) {
*Next = L;
return;
}
if (Cmp(*R, *L)) {
*Next = R;
mergeUseListsImpl(L, R->Next, &R->Next, Cmp);
return;
}
*Next = L;
mergeUseListsImpl(L->Next, R, &L->Next, Cmp);
}
// 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);
}
};
// 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 };
};
// Create wrappers for C Binding types (see CBindingWrapping.h).
DEFINE_ISA_CONVERSION_FUNCTIONS(Value, LLVMValueRef)
/* 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)
cast<T>(*I);
#endif
(void)Length;
return reinterpret_cast<T**>(Vals);
}
inline LLVMValueRef *wrap(const Value **Vals) {
return reinterpret_cast<LLVMValueRef*>(const_cast<Value**>(Vals));
}
} // End llvm namespace
#endif