aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/llvm16/include/llvm/IR/ValueHandle.h
blob: c0decdba35637941bddf0a9b0a26ebf02acdf87c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
#pragma once

#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-parameter"
#endif

//===- 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

#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif