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-rw-r--r--include/llvm/Support/ValueHandle.h380
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diff --git a/include/llvm/Support/ValueHandle.h b/include/llvm/Support/ValueHandle.h
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-//===- llvm/Support/ValueHandle.h - Value Smart Pointer classes -*- 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 ValueHandle class and its sub-classes.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_SUPPORT_VALUEHANDLE_H
-#define LLVM_SUPPORT_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 };
-};
-
-/// ValueHandleBase - 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:
- /// HandleBaseKind - 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
- };
-
-private:
- PointerIntPair<ValueHandleBase**, 2, HandleBaseKind> PrevPair;
- ValueHandleBase *Next;
-
- // A subclass may want to store some information along with the value
- // pointer. Allow them to do this by making the value pointer a pointer-int
- // pair. The 'setValPtrInt' and 'getValPtrInt' methods below give them this
- // access.
- PointerIntPair<Value*, 2> VP;
-
- ValueHandleBase(const ValueHandleBase&) LLVM_DELETED_FUNCTION;
-public:
- explicit ValueHandleBase(HandleBaseKind Kind)
- : PrevPair(0, Kind), Next(0), VP(0, 0) {}
- ValueHandleBase(HandleBaseKind Kind, Value *V)
- : PrevPair(0, Kind), Next(0), VP(V, 0) {
- if (isValid(VP.getPointer()))
- AddToUseList();
- }
- ValueHandleBase(HandleBaseKind Kind, const ValueHandleBase &RHS)
- : PrevPair(0, Kind), Next(0), VP(RHS.VP) {
- if (isValid(VP.getPointer()))
- AddToExistingUseList(RHS.getPrevPtr());
- }
- ~ValueHandleBase() {
- if (isValid(VP.getPointer()))
- RemoveFromUseList();
- }
-
- Value *operator=(Value *RHS) {
- if (VP.getPointer() == RHS) return RHS;
- if (isValid(VP.getPointer())) RemoveFromUseList();
- VP.setPointer(RHS);
- if (isValid(VP.getPointer())) AddToUseList();
- return RHS;
- }
-
- Value *operator=(const ValueHandleBase &RHS) {
- if (VP.getPointer() == RHS.VP.getPointer()) return RHS.VP.getPointer();
- if (isValid(VP.getPointer())) RemoveFromUseList();
- VP.setPointer(RHS.VP.getPointer());
- if (isValid(VP.getPointer())) AddToExistingUseList(RHS.getPrevPtr());
- return VP.getPointer();
- }
-
- Value *operator->() const { return getValPtr(); }
- Value &operator*() const { return *getValPtr(); }
-
-protected:
- Value *getValPtr() const { return VP.getPointer(); }
-
- void setValPtrInt(unsigned K) { VP.setInt(K); }
- unsigned getValPtrInt() const { return VP.getInt(); }
-
- 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); }
-
- /// AddToExistingUseList - Add this ValueHandle to the use list for VP, where
- /// List is the address of either the head of the list or a Next node within
- /// the existing use list.
- void AddToExistingUseList(ValueHandleBase **List);
-
- /// AddToExistingUseListAfter - Add this ValueHandle to the use list after
- /// Node.
- void AddToExistingUseListAfter(ValueHandleBase *Node);
-
- /// AddToUseList - Add this ValueHandle to the use list for VP.
- void AddToUseList();
- /// RemoveFromUseList - Remove this ValueHandle from its current use list.
- void RemoveFromUseList();
-};
-
-/// WeakVH - 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) {}
-
- 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;
- }
-};
-
-/// AssertingVH - 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
- {
-
-#ifndef NDEBUG
- ValueTy *getValPtr() const {
- return static_cast<ValueTy*>(ValueHandleBase::getValPtr());
- }
- void setValPtr(ValueTy *P) {
- ValueHandleBase::operator=(GetAsValue(P));
- }
-#else
- ValueTy *ThePtr;
- ValueTy *getValPtr() const { return ThePtr; }
- void setValPtr(ValueTy *P) { ThePtr = P; }
-#endif
-
- // 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:
-#ifndef NDEBUG
- AssertingVH() : ValueHandleBase(Assert) {}
- AssertingVH(ValueTy *P) : ValueHandleBase(Assert, GetAsValue(P)) {}
- AssertingVH(const AssertingVH &RHS) : ValueHandleBase(Assert, RHS) {}
-#else
- AssertingVH() : ThePtr(0) {}
- AssertingVH(ValueTy *P) : ThePtr(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> > {
- typedef DenseMapInfo<T*> PointerInfo;
- static inline AssertingVH<T> getEmptyKey() {
- return AssertingVH<T>(PointerInfo::getEmptyKey());
- }
- static inline T* getTombstoneKey() {
- return AssertingVH<T>(PointerInfo::getTombstoneKey());
- }
- static unsigned getHashValue(const AssertingVH<T> &Val) {
- return PointerInfo::getHashValue(Val);
- }
- static bool isEqual(const AssertingVH<T> &LHS, const AssertingVH<T> &RHS) {
- return LHS == RHS;
- }
-};
-
-template <typename T>
-struct isPodLike<AssertingVH<T> > {
-#ifdef NDEBUG
- static const bool value = true;
-#else
- static const bool value = false;
-#endif
-};
-
-
-/// TrackingVH - This is a value handle that tracks a Value (or Value subclass),
-/// even across RAUW operations.
-///
-/// 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)) {}
- TrackingVH(const TrackingVH &RHS) : ValueHandleBase(Tracking, RHS) {}
-
- operator ValueTy*() const {
- return getValPtr();
- }
-
- ValueTy *operator=(ValueTy *RHS) {
- setValPtr(RHS);
- return getValPtr();
- }
- ValueTy *operator=(const TrackingVH<ValueTy> &RHS) {
- setValPtr(RHS.getValPtr());
- return getValPtr();
- }
-
- ValueTy *operator->() const { return getValPtr(); }
- ValueTy &operator*() const { return *getValPtr(); }
-};
-
-/// CallbackVH - 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 and a virtual destructor.
-class CallbackVH : public ValueHandleBase {
- virtual void anchor();
-protected:
- CallbackVH(const CallbackVH &RHS)
- : ValueHandleBase(Callback, RHS) {}
-
- virtual ~CallbackVH() {}
-
- void setValPtr(Value *P) {
- ValueHandleBase::operator=(P);
- }
-
-public:
- CallbackVH() : ValueHandleBase(Callback) {}
- CallbackVH(Value *P) : ValueHandleBase(Callback, P) {}
-
- operator Value*() const {
- return getValPtr();
- }
-
- /// 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(NULL); }
-
- /// 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