llvm.org GIT mirror llvm / 48973d7 include / llvm / IR / Attributes.h
48973d7

Tree @48973d7 (Download .tar.gz)

Attributes.h @48973d7raw · history · 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
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
//===- llvm/Attributes.h - Container for Attributes -------------*- 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
//
//===----------------------------------------------------------------------===//
//
/// \file
/// This file contains the simple types necessary to represent the
/// attributes associated with functions and their calls.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_IR_ATTRIBUTES_H
#define LLVM_IR_ATTRIBUTES_H

#include "llvm-c/Types.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/Support/PointerLikeTypeTraits.h"
#include <bitset>
#include <cassert>
#include <cstdint>
#include <map>
#include <string>
#include <utility>

namespace llvm {

class AttrBuilder;
class AttributeImpl;
class AttributeListImpl;
class AttributeSetNode;
template<typename T> struct DenseMapInfo;
class Function;
class LLVMContext;
class Type;

//===----------------------------------------------------------------------===//
/// \class
/// Functions, function parameters, and return types can have attributes
/// to indicate how they should be treated by optimizations and code
/// generation. This class represents one of those attributes. It's light-weight
/// and should be passed around by-value.
class Attribute {
public:
  /// This enumeration lists the attributes that can be associated with
  /// parameters, function results, or the function itself.
  ///
  /// Note: The `uwtable' attribute is about the ABI or the user mandating an
  /// entry in the unwind table. The `nounwind' attribute is about an exception
  /// passing by the function.
  ///
  /// In a theoretical system that uses tables for profiling and SjLj for
  /// exceptions, they would be fully independent. In a normal system that uses
  /// tables for both, the semantics are:
  ///
  /// nil                = Needs an entry because an exception might pass by.
  /// nounwind           = No need for an entry
  /// uwtable            = Needs an entry because the ABI says so and because
  ///                      an exception might pass by.
  /// uwtable + nounwind = Needs an entry because the ABI says so.

  enum AttrKind {
    // IR-Level Attributes
    None,                  ///< No attributes have been set
    #define GET_ATTR_ENUM
    #include "llvm/IR/Attributes.inc"
    EndAttrKinds           ///< Sentinal value useful for loops
  };

private:
  AttributeImpl *pImpl = nullptr;

  Attribute(AttributeImpl *A) : pImpl(A) {}

public:
  Attribute() = default;

  //===--------------------------------------------------------------------===//
  // Attribute Construction
  //===--------------------------------------------------------------------===//

  /// Return a uniquified Attribute object.
  static Attribute get(LLVMContext &Context, AttrKind Kind, uint64_t Val = 0);
  static Attribute get(LLVMContext &Context, StringRef Kind,
                       StringRef Val = StringRef());
  static Attribute get(LLVMContext &Context, AttrKind Kind, Type *Ty);

  /// Return a uniquified Attribute object that has the specific
  /// alignment set.
  static Attribute getWithAlignment(LLVMContext &Context, uint64_t Align);
  static Attribute getWithStackAlignment(LLVMContext &Context, uint64_t Align);
  static Attribute getWithDereferenceableBytes(LLVMContext &Context,
                                              uint64_t Bytes);
  static Attribute getWithDereferenceableOrNullBytes(LLVMContext &Context,
                                                     uint64_t Bytes);
  static Attribute getWithAllocSizeArgs(LLVMContext &Context,
                                        unsigned ElemSizeArg,
                                        const Optional<unsigned> &NumElemsArg);
  static Attribute getWithByValType(LLVMContext &Context, Type *Ty);

  //===--------------------------------------------------------------------===//
  // Attribute Accessors
  //===--------------------------------------------------------------------===//

  /// Return true if the attribute is an Attribute::AttrKind type.
  bool isEnumAttribute() const;

  /// Return true if the attribute is an integer attribute.
  bool isIntAttribute() const;

  /// Return true if the attribute is a string (target-dependent)
  /// attribute.
  bool isStringAttribute() const;

  /// Return true if the attribute is a type attribute.
  bool isTypeAttribute() const;

  /// Return true if the attribute is present.
  bool hasAttribute(AttrKind Val) const;

  /// Return true if the target-dependent attribute is present.
  bool hasAttribute(StringRef Val) const;

  /// Return the attribute's kind as an enum (Attribute::AttrKind). This
  /// requires the attribute to be an enum or integer attribute.
  Attribute::AttrKind getKindAsEnum() const;

  /// Return the attribute's value as an integer. This requires that the
  /// attribute be an integer attribute.
  uint64_t getValueAsInt() const;

  /// Return the attribute's kind as a string. This requires the
  /// attribute to be a string attribute.
  StringRef getKindAsString() const;

  /// Return the attribute's value as a string. This requires the
  /// attribute to be a string attribute.
  StringRef getValueAsString() const;

  /// Return the attribute's value as a Type. This requires the attribute to be
  /// a type attribute.
  Type *getValueAsType() const;

  /// Returns the alignment field of an attribute as a byte alignment
  /// value.
  unsigned getAlignment() const;

  /// Returns the stack alignment field of an attribute as a byte
  /// alignment value.
  unsigned getStackAlignment() const;

  /// Returns the number of dereferenceable bytes from the
  /// dereferenceable attribute.
  uint64_t getDereferenceableBytes() const;

  /// Returns the number of dereferenceable_or_null bytes from the
  /// dereferenceable_or_null attribute.
  uint64_t getDereferenceableOrNullBytes() const;

  /// Returns the argument numbers for the allocsize attribute (or pair(0, 0)
  /// if not known).
  std::pair<unsigned, Optional<unsigned>> getAllocSizeArgs() const;

  /// The Attribute is converted to a string of equivalent mnemonic. This
  /// is, presumably, for writing out the mnemonics for the assembly writer.
  std::string getAsString(bool InAttrGrp = false) const;

  /// Equality and non-equality operators.
  bool operator==(Attribute A) const { return pImpl == A.pImpl; }
  bool operator!=(Attribute A) const { return pImpl != A.pImpl; }

  /// Less-than operator. Useful for sorting the attributes list.
  bool operator<(Attribute A) const;

  void Profile(FoldingSetNodeID &ID) const {
    ID.AddPointer(pImpl);
  }

  /// Return a raw pointer that uniquely identifies this attribute.
  void *getRawPointer() const {
    return pImpl;
  }

  /// Get an attribute from a raw pointer created by getRawPointer.
  static Attribute fromRawPointer(void *RawPtr) {
    return Attribute(reinterpret_cast<AttributeImpl*>(RawPtr));
  }
};

// Specialized opaque value conversions.
inline LLVMAttributeRef wrap(Attribute Attr) {
  return reinterpret_cast<LLVMAttributeRef>(Attr.getRawPointer());
}

// Specialized opaque value conversions.
inline Attribute unwrap(LLVMAttributeRef Attr) {
  return Attribute::fromRawPointer(Attr);
}

//===----------------------------------------------------------------------===//
/// \class
/// This class holds the attributes for a particular argument, parameter,
/// function, or return value. It is an immutable value type that is cheap to
/// copy. Adding and removing enum attributes is intended to be fast, but adding
/// and removing string or integer attributes involves a FoldingSet lookup.
class AttributeSet {
  friend AttributeListImpl;
  template <typename Ty> friend struct DenseMapInfo;

  // TODO: Extract AvailableAttrs from AttributeSetNode and store them here.
  // This will allow an efficient implementation of addAttribute and
  // removeAttribute for enum attrs.

  /// Private implementation pointer.
  AttributeSetNode *SetNode = nullptr;

private:
  explicit AttributeSet(AttributeSetNode *ASN) : SetNode(ASN) {}

public:
  /// AttributeSet is a trivially copyable value type.
  AttributeSet() = default;
  AttributeSet(const AttributeSet &) = default;
  ~AttributeSet() = default;

  static AttributeSet get(LLVMContext &C, const AttrBuilder &B);
  static AttributeSet get(LLVMContext &C, ArrayRef<Attribute> Attrs);

  bool operator==(const AttributeSet &O) const { return SetNode == O.SetNode; }
  bool operator!=(const AttributeSet &O) const { return !(*this == O); }

  /// Add an argument attribute. Returns a new set because attribute sets are
  /// immutable.
  LLVM_NODISCARD AttributeSet addAttribute(LLVMContext &C,
                                           Attribute::AttrKind Kind) const;

  /// Add a target-dependent attribute. Returns a new set because attribute sets
  /// are immutable.
  LLVM_NODISCARD AttributeSet addAttribute(LLVMContext &C, StringRef Kind,
                                           StringRef Value = StringRef()) const;

  /// Add attributes to the attribute set. Returns a new set because attribute
  /// sets are immutable.
  LLVM_NODISCARD AttributeSet addAttributes(LLVMContext &C,
                                            AttributeSet AS) const;

  /// Remove the specified attribute from this set. Returns a new set because
  /// attribute sets are immutable.
  LLVM_NODISCARD AttributeSet removeAttribute(LLVMContext &C,
                                              Attribute::AttrKind Kind) const;

  /// Remove the specified attribute from this set. Returns a new set because
  /// attribute sets are immutable.
  LLVM_NODISCARD AttributeSet removeAttribute(LLVMContext &C,
                                              StringRef Kind) const;

  /// Remove the specified attributes from this set. Returns a new set because
  /// attribute sets are immutable.
  LLVM_NODISCARD AttributeSet
  removeAttributes(LLVMContext &C, const AttrBuilder &AttrsToRemove) const;

  /// Return the number of attributes in this set.
  unsigned getNumAttributes() const;

  /// Return true if attributes exists in this set.
  bool hasAttributes() const { return SetNode != nullptr; }

  /// Return true if the attribute exists in this set.
  bool hasAttribute(Attribute::AttrKind Kind) const;

  /// Return true if the attribute exists in this set.
  bool hasAttribute(StringRef Kind) const;

  /// Return the attribute object.
  Attribute getAttribute(Attribute::AttrKind Kind) const;

  /// Return the target-dependent attribute object.
  Attribute getAttribute(StringRef Kind) const;

  unsigned getAlignment() const;
  unsigned getStackAlignment() const;
  uint64_t getDereferenceableBytes() const;
  uint64_t getDereferenceableOrNullBytes() const;
  Type *getByValType() const;
  std::pair<unsigned, Optional<unsigned>> getAllocSizeArgs() const;
  std::string getAsString(bool InAttrGrp = false) const;

  using iterator = const Attribute *;

  iterator begin() const;
  iterator end() const;
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  void dump() const;
#endif
};

//===----------------------------------------------------------------------===//
/// \class
/// Provide DenseMapInfo for AttributeSet.
template <> struct DenseMapInfo<AttributeSet> {
  static AttributeSet getEmptyKey() {
    auto Val = static_cast<uintptr_t>(-1);
    Val <<= PointerLikeTypeTraits<void *>::NumLowBitsAvailable;
    return AttributeSet(reinterpret_cast<AttributeSetNode *>(Val));
  }

  static AttributeSet getTombstoneKey() {
    auto Val = static_cast<uintptr_t>(-2);
    Val <<= PointerLikeTypeTraits<void *>::NumLowBitsAvailable;
    return AttributeSet(reinterpret_cast<AttributeSetNode *>(Val));
  }

  static unsigned getHashValue(AttributeSet AS) {
    return (unsigned((uintptr_t)AS.SetNode) >> 4) ^
           (unsigned((uintptr_t)AS.SetNode) >> 9);
  }

  static bool isEqual(AttributeSet LHS, AttributeSet RHS) { return LHS == RHS; }
};

//===----------------------------------------------------------------------===//
/// \class
/// This class holds the attributes for a function, its return value, and
/// its parameters. You access the attributes for each of them via an index into
/// the AttributeList object. The function attributes are at index
/// `AttributeList::FunctionIndex', the return value is at index
/// `AttributeList::ReturnIndex', and the attributes for the parameters start at
/// index `AttributeList::FirstArgIndex'.
class AttributeList {
public:
  enum AttrIndex : unsigned {
    ReturnIndex = 0U,
    FunctionIndex = ~0U,
    FirstArgIndex = 1,
  };

private:
  friend class AttrBuilder;
  friend class AttributeListImpl;
  friend class AttributeSet;
  friend class AttributeSetNode;
  template <typename Ty> friend struct DenseMapInfo;

  /// The attributes that we are managing. This can be null to represent
  /// the empty attributes list.
  AttributeListImpl *pImpl = nullptr;

public:
  /// Create an AttributeList with the specified parameters in it.
  static AttributeList get(LLVMContext &C,
                           ArrayRef<std::pair<unsigned, Attribute>> Attrs);
  static AttributeList get(LLVMContext &C,
                           ArrayRef<std::pair<unsigned, AttributeSet>> Attrs);

  /// Create an AttributeList from attribute sets for a function, its
  /// return value, and all of its arguments.
  static AttributeList get(LLVMContext &C, AttributeSet FnAttrs,
                           AttributeSet RetAttrs,
                           ArrayRef<AttributeSet> ArgAttrs);

private:
  explicit AttributeList(AttributeListImpl *LI) : pImpl(LI) {}

  static AttributeList getImpl(LLVMContext &C, ArrayRef<AttributeSet> AttrSets);

public:
  AttributeList() = default;

  //===--------------------------------------------------------------------===//
  // AttributeList Construction and Mutation
  //===--------------------------------------------------------------------===//

  /// Return an AttributeList with the specified parameters in it.
  static AttributeList get(LLVMContext &C, ArrayRef<AttributeList> Attrs);
  static AttributeList get(LLVMContext &C, unsigned Index,
                           ArrayRef<Attribute::AttrKind> Kinds);
  static AttributeList get(LLVMContext &C, unsigned Index,
                           ArrayRef<StringRef> Kind);
  static AttributeList get(LLVMContext &C, unsigned Index,
                           const AttrBuilder &B);

  /// Add an attribute to the attribute set at the given index.
  /// Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList addAttribute(LLVMContext &C, unsigned Index,
                                            Attribute::AttrKind Kind) const;

  /// Add an attribute to the attribute set at the given index.
  /// Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList
  addAttribute(LLVMContext &C, unsigned Index, StringRef Kind,
               StringRef Value = StringRef()) const;

  /// Add an attribute to the attribute set at the given index.
  /// Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList addAttribute(LLVMContext &C, unsigned Index,
                                            Attribute A) const;

  /// Add attributes to the attribute set at the given index.
  /// Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList addAttributes(LLVMContext &C, unsigned Index,
                                             const AttrBuilder &B) const;

  /// Add an argument attribute to the list. Returns a new list because
  /// attribute lists are immutable.
  LLVM_NODISCARD AttributeList addParamAttribute(
      LLVMContext &C, unsigned ArgNo, Attribute::AttrKind Kind) const {
    return addAttribute(C, ArgNo + FirstArgIndex, Kind);
  }

  /// Add an argument attribute to the list. Returns a new list because
  /// attribute lists are immutable.
  LLVM_NODISCARD AttributeList
  addParamAttribute(LLVMContext &C, unsigned ArgNo, StringRef Kind,
                    StringRef Value = StringRef()) const {
    return addAttribute(C, ArgNo + FirstArgIndex, Kind, Value);
  }

  /// Add an attribute to the attribute list at the given arg indices. Returns a
  /// new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList addParamAttribute(LLVMContext &C,
                                                 ArrayRef<unsigned> ArgNos,
                                                 Attribute A) const;

  /// Add an argument attribute to the list. Returns a new list because
  /// attribute lists are immutable.
  LLVM_NODISCARD AttributeList addParamAttributes(LLVMContext &C,
                                                  unsigned ArgNo,
                                                  const AttrBuilder &B) const {
    return addAttributes(C, ArgNo + FirstArgIndex, B);
  }

  /// Remove the specified attribute at the specified index from this
  /// attribute list. Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList removeAttribute(LLVMContext &C, unsigned Index,
                                               Attribute::AttrKind Kind) const;

  /// Remove the specified attribute at the specified index from this
  /// attribute list. Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList removeAttribute(LLVMContext &C, unsigned Index,
                                               StringRef Kind) const;

  /// Remove the specified attributes at the specified index from this
  /// attribute list. Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList removeAttributes(
      LLVMContext &C, unsigned Index, const AttrBuilder &AttrsToRemove) const;

  /// Remove all attributes at the specified index from this
  /// attribute list. Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList removeAttributes(LLVMContext &C,
                                                unsigned Index) const;

  /// Remove the specified attribute at the specified arg index from this
  /// attribute list. Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList removeParamAttribute(
      LLVMContext &C, unsigned ArgNo, Attribute::AttrKind Kind) const {
    return removeAttribute(C, ArgNo + FirstArgIndex, Kind);
  }

  /// Remove the specified attribute at the specified arg index from this
  /// attribute list. Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList removeParamAttribute(LLVMContext &C,
                                                    unsigned ArgNo,
                                                    StringRef Kind) const {
    return removeAttribute(C, ArgNo + FirstArgIndex, Kind);
  }

  /// Remove the specified attribute at the specified arg index from this
  /// attribute list. Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList removeParamAttributes(
      LLVMContext &C, unsigned ArgNo, const AttrBuilder &AttrsToRemove) const {
    return removeAttributes(C, ArgNo + FirstArgIndex, AttrsToRemove);
  }

  /// Remove all attributes at the specified arg index from this
  /// attribute list. Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList removeParamAttributes(LLVMContext &C,
                                                     unsigned ArgNo) const {
    return removeAttributes(C, ArgNo + FirstArgIndex);
  }

  /// \brief Add the dereferenceable attribute to the attribute set at the given
  /// index. Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList addDereferenceableAttr(LLVMContext &C,
                                                      unsigned Index,
                                                      uint64_t Bytes) const;

  /// \brief Add the dereferenceable attribute to the attribute set at the given
  /// arg index. Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList addDereferenceableParamAttr(
      LLVMContext &C, unsigned ArgNo, uint64_t Bytes) const {
    return addDereferenceableAttr(C, ArgNo + FirstArgIndex, Bytes);
  }

  /// Add the dereferenceable_or_null attribute to the attribute set at
  /// the given index. Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList addDereferenceableOrNullAttr(
      LLVMContext &C, unsigned Index, uint64_t Bytes) const;

  /// Add the dereferenceable_or_null attribute to the attribute set at
  /// the given arg index. Returns a new list because attribute lists are
  /// immutable.
  LLVM_NODISCARD AttributeList addDereferenceableOrNullParamAttr(
      LLVMContext &C, unsigned ArgNo, uint64_t Bytes) const {
    return addDereferenceableOrNullAttr(C, ArgNo + FirstArgIndex, Bytes);
  }

  /// Add the allocsize attribute to the attribute set at the given index.
  /// Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList
  addAllocSizeAttr(LLVMContext &C, unsigned Index, unsigned ElemSizeArg,
                   const Optional<unsigned> &NumElemsArg);

  /// Add the allocsize attribute to the attribute set at the given arg index.
  /// Returns a new list because attribute lists are immutable.
  LLVM_NODISCARD AttributeList
  addAllocSizeParamAttr(LLVMContext &C, unsigned ArgNo, unsigned ElemSizeArg,
                        const Optional<unsigned> &NumElemsArg) {
    return addAllocSizeAttr(C, ArgNo + FirstArgIndex, ElemSizeArg, NumElemsArg);
  }

  //===--------------------------------------------------------------------===//
  // AttributeList Accessors
  //===--------------------------------------------------------------------===//

  /// Retrieve the LLVM context.
  LLVMContext &getContext() const;

  /// The attributes for the specified index are returned.
  AttributeSet getAttributes(unsigned Index) const;

  /// The attributes for the argument or parameter at the given index are
  /// returned.
  AttributeSet getParamAttributes(unsigned ArgNo) const;

  /// The attributes for the ret value are returned.
  AttributeSet getRetAttributes() const;

  /// The function attributes are returned.
  AttributeSet getFnAttributes() const;

  /// Return true if the attribute exists at the given index.
  bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;

  /// Return true if the attribute exists at the given index.
  bool hasAttribute(unsigned Index, StringRef Kind) const;

  /// Return true if attribute exists at the given index.
  bool hasAttributes(unsigned Index) const;

  /// Return true if the attribute exists for the given argument
  bool hasParamAttr(unsigned ArgNo, Attribute::AttrKind Kind) const {
    return hasAttribute(ArgNo + FirstArgIndex, Kind);
  }

  /// Return true if the attribute exists for the given argument
  bool hasParamAttr(unsigned ArgNo, StringRef Kind) const {
    return hasAttribute(ArgNo + FirstArgIndex, Kind);
  }

  /// Return true if attributes exists for the given argument
  bool hasParamAttrs(unsigned ArgNo) const {
    return hasAttributes(ArgNo + FirstArgIndex);
  }

  /// Equivalent to hasAttribute(AttributeList::FunctionIndex, Kind) but
  /// may be faster.
  bool hasFnAttribute(Attribute::AttrKind Kind) const;

  /// Equivalent to hasAttribute(AttributeList::FunctionIndex, Kind) but
  /// may be faster.
  bool hasFnAttribute(StringRef Kind) const;

  /// Equivalent to hasAttribute(ArgNo + FirstArgIndex, Kind).
  bool hasParamAttribute(unsigned ArgNo, Attribute::AttrKind Kind) const;

  /// Return true if the specified attribute is set for at least one
  /// parameter or for the return value. If Index is not nullptr, the index
  /// of a parameter with the specified attribute is provided.
  bool hasAttrSomewhere(Attribute::AttrKind Kind,
                        unsigned *Index = nullptr) const;

  /// Return the attribute object that exists at the given index.
  Attribute getAttribute(unsigned Index, Attribute::AttrKind Kind) const;

  /// Return the attribute object that exists at the given index.
  Attribute getAttribute(unsigned Index, StringRef Kind) const;

  /// Return the attribute object that exists at the arg index.
  Attribute getParamAttr(unsigned ArgNo, Attribute::AttrKind Kind) const {
    return getAttribute(ArgNo + FirstArgIndex, Kind);
  }

  /// Return the attribute object that exists at the given index.
  Attribute getParamAttr(unsigned ArgNo, StringRef Kind) const {
    return getAttribute(ArgNo + FirstArgIndex, Kind);
  }

  /// Return the alignment of the return value.
  unsigned getRetAlignment() const;

  /// Return the alignment for the specified function parameter.
  unsigned getParamAlignment(unsigned ArgNo) const;

  /// Return the byval type for the specified function parameter.
  Type *getParamByValType(unsigned ArgNo) const;

  /// Get the stack alignment.
  unsigned getStackAlignment(unsigned Index) const;

  /// Get the number of dereferenceable bytes (or zero if unknown).
  uint64_t getDereferenceableBytes(unsigned Index) const;

  /// Get the number of dereferenceable bytes (or zero if unknown) of an
  /// arg.
  uint64_t getParamDereferenceableBytes(unsigned ArgNo) const {
    return getDereferenceableBytes(ArgNo + FirstArgIndex);
  }

  /// Get the number of dereferenceable_or_null bytes (or zero if
  /// unknown).
  uint64_t getDereferenceableOrNullBytes(unsigned Index) const;

  /// Get the number of dereferenceable_or_null bytes (or zero if
  /// unknown) of an arg.
  uint64_t getParamDereferenceableOrNullBytes(unsigned ArgNo) const {
    return getDereferenceableOrNullBytes(ArgNo + FirstArgIndex);
  }

  /// Get the allocsize argument numbers (or pair(0, 0) if unknown).
  std::pair<unsigned, Optional<unsigned>>
  getAllocSizeArgs(unsigned Index) const;

  /// Return the attributes at the index as a string.
  std::string getAsString(unsigned Index, bool InAttrGrp = false) const;

  //===--------------------------------------------------------------------===//
  // AttributeList Introspection
  //===--------------------------------------------------------------------===//

  using iterator = const AttributeSet *;

  iterator begin() const;
  iterator end() const;

  unsigned getNumAttrSets() const;

  /// Use these to iterate over the valid attribute indices.
  unsigned index_begin() const { return AttributeList::FunctionIndex; }
  unsigned index_end() const { return getNumAttrSets() - 1; }

  /// operator==/!= - Provide equality predicates.
  bool operator==(const AttributeList &RHS) const { return pImpl == RHS.pImpl; }
  bool operator!=(const AttributeList &RHS) const { return pImpl != RHS.pImpl; }

  /// Return a raw pointer that uniquely identifies this attribute list.
  void *getRawPointer() const {
    return pImpl;
  }

  /// Return true if there are no attributes.
  bool isEmpty() const { return pImpl == nullptr; }

  void dump() const;
};

//===----------------------------------------------------------------------===//
/// \class
/// Provide DenseMapInfo for AttributeList.
template <> struct DenseMapInfo<AttributeList> {
  static AttributeList getEmptyKey() {
    auto Val = static_cast<uintptr_t>(-1);
    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
    return AttributeList(reinterpret_cast<AttributeListImpl *>(Val));
  }

  static AttributeList getTombstoneKey() {
    auto Val = static_cast<uintptr_t>(-2);
    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
    return AttributeList(reinterpret_cast<AttributeListImpl *>(Val));
  }

  static unsigned getHashValue(AttributeList AS) {
    return (unsigned((uintptr_t)AS.pImpl) >> 4) ^
           (unsigned((uintptr_t)AS.pImpl) >> 9);
  }

  static bool isEqual(AttributeList LHS, AttributeList RHS) {
    return LHS == RHS;
  }
};

//===----------------------------------------------------------------------===//
/// \class
/// This class is used in conjunction with the Attribute::get method to
/// create an Attribute object. The object itself is uniquified. The Builder's
/// value, however, is not. So this can be used as a quick way to test for
/// equality, presence of attributes, etc.
class AttrBuilder {
  std::bitset<Attribute::EndAttrKinds> Attrs;
  std::map<std::string, std::string> TargetDepAttrs;
  uint64_t Alignment = 0;
  uint64_t StackAlignment = 0;
  uint64_t DerefBytes = 0;
  uint64_t DerefOrNullBytes = 0;
  uint64_t AllocSizeArgs = 0;
  Type *ByValType = nullptr;

public:
  AttrBuilder() = default;

  AttrBuilder(const Attribute &A) {
    addAttribute(A);
  }

  AttrBuilder(AttributeList AS, unsigned Idx);
  AttrBuilder(AttributeSet AS);

  void clear();

  /// Add an attribute to the builder.
  AttrBuilder &addAttribute(Attribute::AttrKind Val);

  /// Add the Attribute object to the builder.
  AttrBuilder &addAttribute(Attribute A);

  /// Add the target-dependent attribute to the builder.
  AttrBuilder &addAttribute(StringRef A, StringRef V = StringRef());

  /// Remove an attribute from the builder.
  AttrBuilder &removeAttribute(Attribute::AttrKind Val);

  /// Remove the attributes from the builder.
  AttrBuilder &removeAttributes(AttributeList A, uint64_t WithoutIndex);

  /// Remove the target-dependent attribute to the builder.
  AttrBuilder &removeAttribute(StringRef A);

  /// Add the attributes from the builder.
  AttrBuilder &merge(const AttrBuilder &B);

  /// Remove the attributes from the builder.
  AttrBuilder &remove(const AttrBuilder &B);

  /// Return true if the builder has any attribute that's in the
  /// specified builder.
  bool overlaps(const AttrBuilder &B) const;

  /// Return true if the builder has the specified attribute.
  bool contains(Attribute::AttrKind A) const {
    assert((unsigned)A < Attribute::EndAttrKinds && "Attribute out of range!");
    return Attrs[A];
  }

  /// Return true if the builder has the specified target-dependent
  /// attribute.
  bool contains(StringRef A) const;

  /// Return true if the builder has IR-level attributes.
  bool hasAttributes() const;

  /// Return true if the builder has any attribute that's in the
  /// specified attribute.
  bool hasAttributes(AttributeList A, uint64_t Index) const;

  /// Return true if the builder has an alignment attribute.
  bool hasAlignmentAttr() const;

  /// Retrieve the alignment attribute, if it exists.
  uint64_t getAlignment() const { return Alignment; }

  /// Retrieve the stack alignment attribute, if it exists.
  uint64_t getStackAlignment() const { return StackAlignment; }

  /// Retrieve the number of dereferenceable bytes, if the
  /// dereferenceable attribute exists (zero is returned otherwise).
  uint64_t getDereferenceableBytes() const { return DerefBytes; }

  /// Retrieve the number of dereferenceable_or_null bytes, if the
  /// dereferenceable_or_null attribute exists (zero is returned otherwise).
  uint64_t getDereferenceableOrNullBytes() const { return DerefOrNullBytes; }

  /// Retrieve the byval type.
  Type *getByValType() const { return ByValType; }

  /// Retrieve the allocsize args, if the allocsize attribute exists.  If it
  /// doesn't exist, pair(0, 0) is returned.
  std::pair<unsigned, Optional<unsigned>> getAllocSizeArgs() const;

  /// This turns an int alignment (which must be a power of 2) into the
  /// form used internally in Attribute.
  AttrBuilder &addAlignmentAttr(unsigned Align);

  /// This turns an int stack alignment (which must be a power of 2) into
  /// the form used internally in Attribute.
  AttrBuilder &addStackAlignmentAttr(unsigned Align);

  /// This turns the number of dereferenceable bytes into the form used
  /// internally in Attribute.
  AttrBuilder &addDereferenceableAttr(uint64_t Bytes);

  /// This turns the number of dereferenceable_or_null bytes into the
  /// form used internally in Attribute.
  AttrBuilder &addDereferenceableOrNullAttr(uint64_t Bytes);

  /// This turns one (or two) ints into the form used internally in Attribute.
  AttrBuilder &addAllocSizeAttr(unsigned ElemSizeArg,
                                const Optional<unsigned> &NumElemsArg);

  /// This turns a byval type into the form used internally in Attribute.
  AttrBuilder &addByValAttr(Type *Ty);

  /// Add an allocsize attribute, using the representation returned by
  /// Attribute.getIntValue().
  AttrBuilder &addAllocSizeAttrFromRawRepr(uint64_t RawAllocSizeRepr);

  /// Return true if the builder contains no target-independent
  /// attributes.
  bool empty() const { return Attrs.none(); }

  // Iterators for target-dependent attributes.
  using td_type = std::pair<std::string, std::string>;
  using td_iterator = std::map<std::string, std::string>::iterator;
  using td_const_iterator = std::map<std::string, std::string>::const_iterator;
  using td_range = iterator_range<td_iterator>;
  using td_const_range = iterator_range<td_const_iterator>;

  td_iterator td_begin() { return TargetDepAttrs.begin(); }
  td_iterator td_end() { return TargetDepAttrs.end(); }

  td_const_iterator td_begin() const { return TargetDepAttrs.begin(); }
  td_const_iterator td_end() const { return TargetDepAttrs.end(); }

  td_range td_attrs() { return td_range(td_begin(), td_end()); }

  td_const_range td_attrs() const {
    return td_const_range(td_begin(), td_end());
  }

  bool td_empty() const { return TargetDepAttrs.empty(); }

  bool operator==(const AttrBuilder &B);
  bool operator!=(const AttrBuilder &B) {
    return !(*this == B);
  }
};

namespace AttributeFuncs {

/// Which attributes cannot be applied to a type.
AttrBuilder typeIncompatible(Type *Ty);

/// \returns Return true if the two functions have compatible target-independent
/// attributes for inlining purposes.
bool areInlineCompatible(const Function &Caller, const Function &Callee);

/// Merge caller's and callee's attributes.
void mergeAttributesForInlining(Function &Caller, const Function &Callee);

} // end namespace AttributeFuncs

} // end namespace llvm

#endif // LLVM_IR_ATTRIBUTES_H