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thirdparty/capstone/suite/synctools/tablegen/include/llvm/IR/ValueHandle.h

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+//===- ValueHandle.h - Value Smart Pointer classes --------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// 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"
+#include "llvm/Support/Casting.h"
+#include <cassert>
+
+namespace llvm {
+
+/// 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:
+  /// 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, Weak, WeakTracking };
+
+  ValueHandleBase(const ValueHandleBase &RHS)
+      : ValueHandleBase(RHS.PrevPair.getInt(), RHS) {}
+
+  ValueHandleBase(HandleBaseKind Kind, const ValueHandleBase &RHS)
+      : PrevPair(nullptr, Kind), Val(RHS.getValPtr()) {
+    if (isValid(getValPtr()))
+      AddToExistingUseList(RHS.getPrevPtr());
+  }
+
+private:
+  PointerIntPair<ValueHandleBase**, 2, HandleBaseKind> PrevPair;
+  ValueHandleBase *Next = nullptr;
+  Value *Val = nullptr;
+
+  void setValPtr(Value *V) { Val = V; }
+
+public:
+  explicit ValueHandleBase(HandleBaseKind Kind)
+      : PrevPair(nullptr, Kind) {}
+  ValueHandleBase(HandleBaseKind Kind, Value *V)
+      : PrevPair(nullptr, Kind), Val(V) {
+    if (isValid(getValPtr()))
+      AddToUseList();
+  }
+
+  ~ValueHandleBase() {
+    if (isValid(getValPtr()))
+      RemoveFromUseList();
+  }
+
+  Value *operator=(Value *RHS) {
+    if (getValPtr() == RHS)
+      return RHS;
+    if (isValid(getValPtr()))
+      RemoveFromUseList();
+    setValPtr(RHS);
+    if (isValid(getValPtr()))
+      AddToUseList();
+    return RHS;
+  }
+
+  Value *operator=(const ValueHandleBase &RHS) {
+    if (getValPtr() == RHS.getValPtr())
+      return RHS.getValPtr();
+    if (isValid(getValPtr()))
+      RemoveFromUseList();
+    setValPtr(RHS.getValPtr());
+    if (isValid(getValPtr()))
+      AddToExistingUseList(RHS.getPrevPtr());
+    return getValPtr();
+  }
+
+  Value *operator->() const { return getValPtr(); }
+  Value &operator*() const {
+    Value *V = getValPtr();
+    assert(V && "Dereferencing deleted ValueHandle");
+    return *V;
+  }
+
+protected:
+  Value *getValPtr() const { return Val; }
+
+  static bool isValid(Value *V) {
+    return V &&
+           V != DenseMapInfo<Value *>::getEmptyKey() &&
+           V != DenseMapInfo<Value *>::getTombstoneKey();
+  }
+
+  /// Remove this ValueHandle from its current use list.
+  void RemoveFromUseList();
+
+  /// Clear the underlying pointer without clearing the use list.
+  ///
+  /// This should only be used if a derived class has manually removed the
+  /// handle from the use list.
+  void clearValPtr() { setValPtr(nullptr); }
+
+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); }
+
+  /// 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);
+
+  /// Add this ValueHandle to the use list after Node.
+  void AddToExistingUseListAfter(ValueHandleBase *Node);
+
+  /// Add this ValueHandle to the use list for V.
+  void AddToUseList();
+};
+
+/// A nullable Value handle that is nullable.
+///
+/// This is a value handle that points to a value, and nulls itself
+/// out if that value is deleted.
+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> {
+  using SimpleType = Value *;
+
+  static SimpleType getSimplifiedValue(WeakVH &WVH) { return WVH; }
+};
+template <> struct simplify_type<const WeakVH> {
+  using SimpleType = Value *;
+
+  static SimpleType getSimplifiedValue(const WeakVH &WVH) { return WVH; }
+};
+
+// Specialize DenseMapInfo to allow WeakVH to participate in DenseMap.
+template <> struct DenseMapInfo<WeakVH> {
+  static inline WeakVH getEmptyKey() {
+    return WeakVH(DenseMapInfo<Value *>::getEmptyKey());
+  }
+
+  static inline WeakVH getTombstoneKey() {
+    return WeakVH(DenseMapInfo<Value *>::getTombstoneKey());
+  }
+
+  static unsigned getHashValue(const WeakVH &Val) {
+    return DenseMapInfo<Value *>::getHashValue(Val);
+  }
+
+  static bool isEqual(const WeakVH &LHS, const WeakVH &RHS) {
+    return DenseMapInfo<Value *>::isEqual(LHS, RHS);
+  }
+};
+
+/// 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 WeakTrackingVH : public ValueHandleBase {
+public:
+  WeakTrackingVH() : ValueHandleBase(WeakTracking) {}
+  WeakTrackingVH(Value *P) : ValueHandleBase(WeakTracking, P) {}
+  WeakTrackingVH(const WeakTrackingVH &RHS)
+      : ValueHandleBase(WeakTracking, RHS) {}
+
+  WeakTrackingVH &operator=(const WeakTrackingVH &RHS) = default;
+
+  Value *operator=(Value *RHS) {
+    return ValueHandleBase::operator=(RHS);
+  }
+  Value *operator=(const ValueHandleBase &RHS) {
+    return ValueHandleBase::operator=(RHS);
+  }
+
+  operator Value*() const {
+    return getValPtr();
+  }
+
+  bool pointsToAliveValue() const {
+    return ValueHandleBase::isValid(getValPtr());
+  }
+};
+
+// Specialize simplify_type to allow WeakTrackingVH to participate in
+// dyn_cast, isa, etc.
+template <> struct simplify_type<WeakTrackingVH> {
+  using SimpleType = Value *;
+
+  static SimpleType getSimplifiedValue(WeakTrackingVH &WVH) { return WVH; }
+};
+template <> struct simplify_type<const WeakTrackingVH> {
+  using SimpleType = Value *;
+
+  static SimpleType getSimplifiedValue(const WeakTrackingVH &WVH) {
+    return WVH;
+  }
+};
+
+/// 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
+#if LLVM_ENABLE_ABI_BREAKING_CHECKS
+    : public ValueHandleBase
+#endif
+{
+  friend struct DenseMapInfo<AssertingVH<ValueTy>>;
+
+#if LLVM_ENABLE_ABI_BREAKING_CHECKS
+  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:
+#if LLVM_ENABLE_ABI_BREAKING_CHECKS
+  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)) {}
+  AssertingVH(const AssertingVH &) = default;
+#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(); }
+};
+
+// Treat AssertingVH<T> like T* inside maps. This also allows using find_as()
+// to look up a value without constructing a value handle.
+template<typename T>
+struct DenseMapInfo<AssertingVH<T>> : DenseMapInfo<T *> {};
+
+/// 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 attempt to replace a value with one of a type which is
+/// incompatible with any of its outstanding TrackingVHs.
+///
+/// It is an error to read from a TrackingVH that does not point to a valid
+/// value.  A TrackingVH is said to not point to a valid value if either it
+/// hasn't yet been assigned a value yet or because the value it was tracking
+/// has since been deleted.
+///
+/// Assigning a value to a TrackingVH is always allowed, even if said TrackingVH
+/// no longer points to a valid value.
+template <typename ValueTy> class TrackingVH {
+  WeakTrackingVH InnerHandle;
+
+public:
+  ValueTy *getValPtr() const {
+    assert(InnerHandle.pointsToAliveValue() &&
+           "TrackingVH must be non-null and valid on dereference!");
+
+    // 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>(InnerHandle) &&
+           "Tracked Value was replaced by one with an invalid type!");
+    return cast<ValueTy>(InnerHandle);
+  }
+
+  void setValPtr(ValueTy *P) {
+    // Assigning to non-valid TrackingVH's are fine so we just unconditionally
+    // assign here.
+    InnerHandle = 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() = default;
+  TrackingVH(ValueTy *P) { setValPtr(P); }
+
+  operator ValueTy*() const {
+    return getValPtr();
+  }
+
+  ValueTy *operator=(ValueTy *RHS) {
+    setValPtr(RHS);
+    return getValPtr();
+  }
+
+  ValueTy *operator->() const { return getValPtr(); }
+  ValueTy &operator*() const { return *getValPtr(); }
+};
+
+/// 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) {}
+  CallbackVH(const Value *P) : CallbackVH(const_cast<Value *>(P)) {}
+
+  operator Value*() const {
+    return getValPtr();
+  }
+
+  /// 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 WeakTrackingVH 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); }
+
+  /// Callback for Value RAUW.
+  ///
+  /// Called when this->getValPtr()->replaceAllUsesWith(new_value) is called,
+  /// _before_ any of the uses have actually been replaced.  If WeakTrackingVH
+  /// 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 *) {}
+};
+
+/// Value handle that poisons itself if the Value is deleted.
+///
+/// This is a Value Handle that points to a value and poisons itself if the
+/// value is destroyed while the handle is still live.  This is very useful for
+/// catching dangling pointer bugs where an \c AssertingVH cannot be used
+/// because the dangling handle needs to outlive the value without ever being
+/// used.
+///
+/// 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
+/// a PoisoningVH ensures that an assert is triggered if looking up a new value
+/// in the map finds a handle from the old value.
+///
+/// Note that a PoisoningVH handle does *not* follow values across RAUW
+/// operations. This means that RAUW's need to explicitly update the
+/// PoisoningVH'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 PoisoningVH final
+#if LLVM_ENABLE_ABI_BREAKING_CHECKS
+    : public CallbackVH
+#endif
+{
+  friend struct DenseMapInfo<PoisoningVH<ValueTy>>;
+
+  // 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); }
+
+#if LLVM_ENABLE_ABI_BREAKING_CHECKS
+  /// A flag tracking whether this value has been poisoned.
+  ///
+  /// On delete and RAUW, we leave the value pointer alone so that as a raw
+  /// pointer it produces the same value (and we fit into the same key of
+  /// a hash table, etc), but we poison the handle so that any top-level usage
+  /// will fail.
+  bool Poisoned = false;
+
+  Value *getRawValPtr() const { return ValueHandleBase::getValPtr(); }
+  void setRawValPtr(Value *P) { ValueHandleBase::operator=(P); }
+
+  /// Handle deletion by poisoning the handle.
+  void deleted() override {
+    assert(!Poisoned && "Tried to delete an already poisoned handle!");
+    Poisoned = true;
+    RemoveFromUseList();
+  }
+
+  /// Handle RAUW by poisoning the handle.
+  void allUsesReplacedWith(Value *) override {
+    assert(!Poisoned && "Tried to RAUW an already poisoned handle!");
+    Poisoned = true;
+    RemoveFromUseList();
+  }
+#else // LLVM_ENABLE_ABI_BREAKING_CHECKS
+  Value *ThePtr = nullptr;
+
+  Value *getRawValPtr() const { return ThePtr; }
+  void setRawValPtr(Value *P) { ThePtr = P; }
+#endif
+
+  ValueTy *getValPtr() const {
+#if LLVM_ENABLE_ABI_BREAKING_CHECKS
+    assert(!Poisoned && "Accessed a poisoned value handle!");
+#endif
+    return static_cast<ValueTy *>(getRawValPtr());
+  }
+  void setValPtr(ValueTy *P) { setRawValPtr(GetAsValue(P)); }
+
+public:
+  PoisoningVH() = default;
+#if LLVM_ENABLE_ABI_BREAKING_CHECKS
+  PoisoningVH(ValueTy *P) : CallbackVH(GetAsValue(P)) {}
+  PoisoningVH(const PoisoningVH &RHS)
+      : CallbackVH(RHS), Poisoned(RHS.Poisoned) {}
+
+  ~PoisoningVH() {
+    if (Poisoned)
+      clearValPtr();
+  }
+
+  PoisoningVH &operator=(const PoisoningVH &RHS) {
+    if (Poisoned)
+      clearValPtr();
+    CallbackVH::operator=(RHS);
+    Poisoned = RHS.Poisoned;
+    return *this;
+  }
+#else
+  PoisoningVH(ValueTy *P) : ThePtr(GetAsValue(P)) {}
+#endif
+
+  operator ValueTy *() const { return getValPtr(); }
+
+  ValueTy *operator->() const { return getValPtr(); }
+  ValueTy &operator*() const { return *getValPtr(); }
+};
+
+// Specialize DenseMapInfo to allow PoisoningVH to participate in DenseMap.
+template <typename T> struct DenseMapInfo<PoisoningVH<T>> {
+  static inline PoisoningVH<T> getEmptyKey() {
+    PoisoningVH<T> Res;
+    Res.setRawValPtr(DenseMapInfo<Value *>::getEmptyKey());
+    return Res;
+  }
+
+  static inline PoisoningVH<T> getTombstoneKey() {
+    PoisoningVH<T> Res;
+    Res.setRawValPtr(DenseMapInfo<Value *>::getTombstoneKey());
+    return Res;
+  }
+
+  static unsigned getHashValue(const PoisoningVH<T> &Val) {
+    return DenseMapInfo<Value *>::getHashValue(Val.getRawValPtr());
+  }
+
+  static bool isEqual(const PoisoningVH<T> &LHS, const PoisoningVH<T> &RHS) {
+    return DenseMapInfo<Value *>::isEqual(LHS.getRawValPtr(),
+                                          RHS.getRawValPtr());
+  }
+
+  // Allow lookup by T* via find_as(), without constructing a temporary
+  // value handle.
+
+  static unsigned getHashValue(const T *Val) {
+    return DenseMapInfo<Value *>::getHashValue(Val);
+  }
+
+  static bool isEqual(const T *LHS, const PoisoningVH<T> &RHS) {
+    return DenseMapInfo<Value *>::isEqual(LHS, RHS.getRawValPtr());
+  }
+};
+
+} // end namespace llvm
+
+#endif // LLVM_IR_VALUEHANDLE_H