/usr/include/llvm-3.9/llvm/IR/ValueHandle.h is in llvm-3.9-dev 1:3.9.1-19ubuntu1.
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//
// 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 ValueHandle class and its sub-classes.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_IR_VALUEHANDLE_H
#define LLVM_IR_VALUEHANDLE_H
#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/IR/Value.h"
namespace llvm {
class ValueHandleBase;
template<typename From> struct simplify_type;
// ValueHandleBase** is only 4-byte aligned.
template<>
class PointerLikeTypeTraits<ValueHandleBase**> {
public:
static inline void *getAsVoidPointer(ValueHandleBase** P) { return P; }
static inline ValueHandleBase **getFromVoidPointer(void *P) {
return static_cast<ValueHandleBase**>(P);
}
enum { NumLowBitsAvailable = 2 };
};
/// \brief This is the common base class of value handles.
///
/// ValueHandle's are smart pointers to Value's that have special behavior when
/// the value is deleted or ReplaceAllUsesWith'd. See the specific handles
/// below for details.
class ValueHandleBase {
friend class Value;
protected:
/// \brief This indicates what sub class the handle actually is.
///
/// This is to avoid having a vtable for the light-weight handle pointers. The
/// fully general Callback version does have a vtable.
enum HandleBaseKind {
Assert,
Callback,
Tracking,
Weak
};
ValueHandleBase(const ValueHandleBase &RHS)
: ValueHandleBase(RHS.PrevPair.getInt(), RHS) {}
ValueHandleBase(HandleBaseKind Kind, const ValueHandleBase &RHS)
: PrevPair(nullptr, Kind), Next(nullptr), V(RHS.V) {
if (isValid(V))
AddToExistingUseList(RHS.getPrevPtr());
}
private:
PointerIntPair<ValueHandleBase**, 2, HandleBaseKind> PrevPair;
ValueHandleBase *Next;
Value* V;
public:
explicit ValueHandleBase(HandleBaseKind Kind)
: PrevPair(nullptr, Kind), Next(nullptr), V(nullptr) {}
ValueHandleBase(HandleBaseKind Kind, Value *V)
: PrevPair(nullptr, Kind), Next(nullptr), V(V) {
if (isValid(V))
AddToUseList();
}
~ValueHandleBase() {
if (isValid(V))
RemoveFromUseList();
}
Value *operator=(Value *RHS) {
if (V == RHS) return RHS;
if (isValid(V)) RemoveFromUseList();
V = RHS;
if (isValid(V)) AddToUseList();
return RHS;
}
Value *operator=(const ValueHandleBase &RHS) {
if (V == RHS.V) return RHS.V;
if (isValid(V)) RemoveFromUseList();
V = RHS.V;
if (isValid(V)) AddToExistingUseList(RHS.getPrevPtr());
return V;
}
Value *operator->() const { return V; }
Value &operator*() const { return *V; }
protected:
Value *getValPtr() const { return V; }
static bool isValid(Value *V) {
return V &&
V != DenseMapInfo<Value *>::getEmptyKey() &&
V != DenseMapInfo<Value *>::getTombstoneKey();
}
public:
// Callbacks made from Value.
static void ValueIsDeleted(Value *V);
static void ValueIsRAUWd(Value *Old, Value *New);
private:
// Internal implementation details.
ValueHandleBase **getPrevPtr() const { return PrevPair.getPointer(); }
HandleBaseKind getKind() const { return PrevPair.getInt(); }
void setPrevPtr(ValueHandleBase **Ptr) { PrevPair.setPointer(Ptr); }
/// \brief Add this ValueHandle to the use list for V.
///
/// List is the address of either the head of the list or a Next node within
/// the existing use list.
void AddToExistingUseList(ValueHandleBase **List);
/// \brief Add this ValueHandle to the use list after Node.
void AddToExistingUseListAfter(ValueHandleBase *Node);
/// \brief Add this ValueHandle to the use list for V.
void AddToUseList();
/// \brief Remove this ValueHandle from its current use list.
void RemoveFromUseList();
};
/// \brief Value handle that is nullable, but tries to track the Value.
///
/// This is a value handle that tries hard to point to a Value, even across
/// RAUW operations, but will null itself out if the value is destroyed. this
/// is useful for advisory sorts of information, but should not be used as the
/// key of a map (since the map would have to rearrange itself when the pointer
/// changes).
class WeakVH : public ValueHandleBase {
public:
WeakVH() : ValueHandleBase(Weak) {}
WeakVH(Value *P) : ValueHandleBase(Weak, P) {}
WeakVH(const WeakVH &RHS)
: ValueHandleBase(Weak, RHS) {}
WeakVH &operator=(const WeakVH &RHS) = default;
Value *operator=(Value *RHS) {
return ValueHandleBase::operator=(RHS);
}
Value *operator=(const ValueHandleBase &RHS) {
return ValueHandleBase::operator=(RHS);
}
operator Value*() const {
return getValPtr();
}
};
// Specialize simplify_type to allow WeakVH to participate in
// dyn_cast, isa, etc.
template <> struct simplify_type<WeakVH> {
typedef Value *SimpleType;
static SimpleType getSimplifiedValue(WeakVH &WVH) { return WVH; }
};
template <> struct simplify_type<const WeakVH> {
typedef Value *SimpleType;
static SimpleType getSimplifiedValue(const WeakVH &WVH) { return WVH; }
};
/// \brief Value handle that asserts if the Value is deleted.
///
/// This is a Value Handle that points to a value and asserts out if the value
/// is destroyed while the handle is still live. This is very useful for
/// catching dangling pointer bugs and other things which can be non-obvious.
/// One particularly useful place to use this is as the Key of a map. Dangling
/// pointer bugs often lead to really subtle bugs that only occur if another
/// object happens to get allocated to the same address as the old one. Using
/// an AssertingVH ensures that an assert is triggered as soon as the bad
/// delete occurs.
///
/// Note that an AssertingVH handle does *not* follow values across RAUW
/// operations. This means that RAUW's need to explicitly update the
/// AssertingVH's as it moves. This is required because in non-assert mode this
/// class turns into a trivial wrapper around a pointer.
template <typename ValueTy>
class AssertingVH
#ifndef NDEBUG
: public ValueHandleBase
#endif
{
friend struct DenseMapInfo<AssertingVH<ValueTy> >;
#ifndef NDEBUG
Value *getRawValPtr() const { return ValueHandleBase::getValPtr(); }
void setRawValPtr(Value *P) { ValueHandleBase::operator=(P); }
#else
Value *ThePtr;
Value *getRawValPtr() const { return ThePtr; }
void setRawValPtr(Value *P) { ThePtr = P; }
#endif
// Convert a ValueTy*, which may be const, to the raw Value*.
static Value *GetAsValue(Value *V) { return V; }
static Value *GetAsValue(const Value *V) { return const_cast<Value*>(V); }
ValueTy *getValPtr() const { return static_cast<ValueTy *>(getRawValPtr()); }
void setValPtr(ValueTy *P) { setRawValPtr(GetAsValue(P)); }
public:
#ifndef NDEBUG
AssertingVH() : ValueHandleBase(Assert) {}
AssertingVH(ValueTy *P) : ValueHandleBase(Assert, GetAsValue(P)) {}
AssertingVH(const AssertingVH &RHS) : ValueHandleBase(Assert, RHS) {}
#else
AssertingVH() : ThePtr(nullptr) {}
AssertingVH(ValueTy *P) : ThePtr(GetAsValue(P)) {}
#endif
operator ValueTy*() const {
return getValPtr();
}
ValueTy *operator=(ValueTy *RHS) {
setValPtr(RHS);
return getValPtr();
}
ValueTy *operator=(const AssertingVH<ValueTy> &RHS) {
setValPtr(RHS.getValPtr());
return getValPtr();
}
ValueTy *operator->() const { return getValPtr(); }
ValueTy &operator*() const { return *getValPtr(); }
};
// Specialize DenseMapInfo to allow AssertingVH to participate in DenseMap.
template<typename T>
struct DenseMapInfo<AssertingVH<T> > {
static inline AssertingVH<T> getEmptyKey() {
AssertingVH<T> Res;
Res.setRawValPtr(DenseMapInfo<Value *>::getEmptyKey());
return Res;
}
static inline AssertingVH<T> getTombstoneKey() {
AssertingVH<T> Res;
Res.setRawValPtr(DenseMapInfo<Value *>::getTombstoneKey());
return Res;
}
static unsigned getHashValue(const AssertingVH<T> &Val) {
return DenseMapInfo<Value *>::getHashValue(Val.getRawValPtr());
}
static bool isEqual(const AssertingVH<T> &LHS, const AssertingVH<T> &RHS) {
return DenseMapInfo<Value *>::isEqual(LHS.getRawValPtr(),
RHS.getRawValPtr());
}
};
template <typename T>
struct isPodLike<AssertingVH<T> > {
#ifdef NDEBUG
static const bool value = true;
#else
static const bool value = false;
#endif
};
/// \brief Value handle that tracks a Value across RAUW.
///
/// TrackingVH is designed for situations where a client needs to hold a handle
/// to a Value (or subclass) across some operations which may move that value,
/// but should never destroy it or replace it with some unacceptable type.
///
/// It is an error to do anything with a TrackingVH whose value has been
/// destroyed, except to destruct it.
///
/// It is an error to attempt to replace a value with one of a type which is
/// incompatible with any of its outstanding TrackingVHs.
template<typename ValueTy>
class TrackingVH : public ValueHandleBase {
void CheckValidity() const {
Value *VP = ValueHandleBase::getValPtr();
// Null is always ok.
if (!VP) return;
// Check that this value is valid (i.e., it hasn't been deleted). We
// explicitly delay this check until access to avoid requiring clients to be
// unnecessarily careful w.r.t. destruction.
assert(ValueHandleBase::isValid(VP) && "Tracked Value was deleted!");
// Check that the value is a member of the correct subclass. We would like
// to check this property on assignment for better debugging, but we don't
// want to require a virtual interface on this VH. Instead we allow RAUW to
// replace this value with a value of an invalid type, and check it here.
assert(isa<ValueTy>(VP) &&
"Tracked Value was replaced by one with an invalid type!");
}
ValueTy *getValPtr() const {
CheckValidity();
return (ValueTy*)ValueHandleBase::getValPtr();
}
void setValPtr(ValueTy *P) {
CheckValidity();
ValueHandleBase::operator=(GetAsValue(P));
}
// Convert a ValueTy*, which may be const, to the type the base
// class expects.
static Value *GetAsValue(Value *V) { return V; }
static Value *GetAsValue(const Value *V) { return const_cast<Value*>(V); }
public:
TrackingVH() : ValueHandleBase(Tracking) {}
TrackingVH(ValueTy *P) : ValueHandleBase(Tracking, GetAsValue(P)) {}
operator ValueTy*() const {
return getValPtr();
}
ValueTy *operator=(ValueTy *RHS) {
setValPtr(RHS);
return getValPtr();
}
ValueTy *operator->() const { return getValPtr(); }
ValueTy &operator*() const { return *getValPtr(); }
};
/// \brief Value handle with callbacks on RAUW and destruction.
///
/// This is a value handle that allows subclasses to define callbacks that run
/// when the underlying Value has RAUW called on it or is destroyed. This
/// class can be used as the key of a map, as long as the user takes it out of
/// the map before calling setValPtr() (since the map has to rearrange itself
/// when the pointer changes). Unlike ValueHandleBase, this class has a vtable.
class CallbackVH : public ValueHandleBase {
virtual void anchor();
protected:
~CallbackVH() = default;
CallbackVH(const CallbackVH &) = default;
CallbackVH &operator=(const CallbackVH &) = default;
void setValPtr(Value *P) {
ValueHandleBase::operator=(P);
}
public:
CallbackVH() : ValueHandleBase(Callback) {}
CallbackVH(Value *P) : ValueHandleBase(Callback, P) {}
operator Value*() const {
return getValPtr();
}
/// \brief Callback for Value destruction.
///
/// Called when this->getValPtr() is destroyed, inside ~Value(), so you
/// may call any non-virtual Value method on getValPtr(), but no subclass
/// methods. If WeakVH were implemented as a CallbackVH, it would use this
/// method to call setValPtr(NULL). AssertingVH would use this method to
/// cause an assertion failure.
///
/// All implementations must remove the reference from this object to the
/// Value that's being destroyed.
virtual void deleted() { setValPtr(nullptr); }
/// \brief Callback for Value RAUW.
///
/// Called when this->getValPtr()->replaceAllUsesWith(new_value) is called,
/// _before_ any of the uses have actually been replaced. If WeakVH were
/// implemented as a CallbackVH, it would use this method to call
/// setValPtr(new_value). AssertingVH would do nothing in this method.
virtual void allUsesReplacedWith(Value *) {}
};
} // End llvm namespace
#endif
|