1//===-- llvm/Attributes.h - Container for Attributes ------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9///
10/// \file
11/// \brief This file contains the simple types necessary to represent the
12/// attributes associated with functions and their calls.
13///
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_IR_ATTRIBUTES_H
17#define LLVM_IR_ATTRIBUTES_H
18
19#include "llvm/ADT/ArrayRef.h"
20#include "llvm/ADT/FoldingSet.h"
21#include "llvm/Support/Compiler.h"
22#include "llvm/Support/PointerLikeTypeTraits.h"
23#include <bitset>
24#include <cassert>
25#include <map>
26#include <string>
27
28namespace llvm {
29
30class AttrBuilder;
31class AttributeImpl;
32class AttributeSetImpl;
33class AttributeSetNode;
34class Constant;
35template<typename T> struct DenseMapInfo;
36class Function;
37class LLVMContext;
38class Type;
39
40//===----------------------------------------------------------------------===//
41/// \class
42/// \brief Functions, function parameters, and return types can have attributes
43/// to indicate how they should be treated by optimizations and code
44/// generation. This class represents one of those attributes. It's light-weight
45/// and should be passed around by-value.
46class Attribute {
47public:
48  /// This enumeration lists the attributes that can be associated with
49  /// parameters, function results, or the function itself.
50  ///
51  /// Note: The `uwtable' attribute is about the ABI or the user mandating an
52  /// entry in the unwind table. The `nounwind' attribute is about an exception
53  /// passing by the function.
54  ///
55  /// In a theoretical system that uses tables for profiling and SjLj for
56  /// exceptions, they would be fully independent. In a normal system that uses
57  /// tables for both, the semantics are:
58  ///
59  /// nil                = Needs an entry because an exception might pass by.
60  /// nounwind           = No need for an entry
61  /// uwtable            = Needs an entry because the ABI says so and because
62  ///                      an exception might pass by.
63  /// uwtable + nounwind = Needs an entry because the ABI says so.
64
65  enum AttrKind {
66    // IR-Level Attributes
67    None,                  ///< No attributes have been set
68    #define GET_ATTR_ENUM
69    #include "llvm/IR/Attributes.inc"
70    EndAttrKinds           ///< Sentinal value useful for loops
71  };
72
73private:
74  AttributeImpl *pImpl;
75  Attribute(AttributeImpl *A) : pImpl(A) {}
76
77public:
78  Attribute() : pImpl(nullptr) {}
79
80  //===--------------------------------------------------------------------===//
81  // Attribute Construction
82  //===--------------------------------------------------------------------===//
83
84  /// \brief Return a uniquified Attribute object.
85  static Attribute get(LLVMContext &Context, AttrKind Kind, uint64_t Val = 0);
86  static Attribute get(LLVMContext &Context, StringRef Kind,
87                       StringRef Val = StringRef());
88
89  /// \brief Return a uniquified Attribute object that has the specific
90  /// alignment set.
91  static Attribute getWithAlignment(LLVMContext &Context, uint64_t Align);
92  static Attribute getWithStackAlignment(LLVMContext &Context, uint64_t Align);
93  static Attribute getWithDereferenceableBytes(LLVMContext &Context,
94                                              uint64_t Bytes);
95  static Attribute getWithDereferenceableOrNullBytes(LLVMContext &Context,
96                                                     uint64_t Bytes);
97
98  //===--------------------------------------------------------------------===//
99  // Attribute Accessors
100  //===--------------------------------------------------------------------===//
101
102  /// \brief Return true if the attribute is an Attribute::AttrKind type.
103  bool isEnumAttribute() const;
104
105  /// \brief Return true if the attribute is an integer attribute.
106  bool isIntAttribute() const;
107
108  /// \brief Return true if the attribute is a string (target-dependent)
109  /// attribute.
110  bool isStringAttribute() const;
111
112  /// \brief Return true if the attribute is present.
113  bool hasAttribute(AttrKind Val) const;
114
115  /// \brief Return true if the target-dependent attribute is present.
116  bool hasAttribute(StringRef Val) const;
117
118  /// \brief Return the attribute's kind as an enum (Attribute::AttrKind). This
119  /// requires the attribute to be an enum or alignment attribute.
120  Attribute::AttrKind getKindAsEnum() const;
121
122  /// \brief Return the attribute's value as an integer. This requires that the
123  /// attribute be an alignment attribute.
124  uint64_t getValueAsInt() const;
125
126  /// \brief Return the attribute's kind as a string. This requires the
127  /// attribute to be a string attribute.
128  StringRef getKindAsString() const;
129
130  /// \brief Return the attribute's value as a string. This requires the
131  /// attribute to be a string attribute.
132  StringRef getValueAsString() const;
133
134  /// \brief Returns the alignment field of an attribute as a byte alignment
135  /// value.
136  unsigned getAlignment() const;
137
138  /// \brief Returns the stack alignment field of an attribute as a byte
139  /// alignment value.
140  unsigned getStackAlignment() const;
141
142  /// \brief Returns the number of dereferenceable bytes from the
143  /// dereferenceable attribute.
144  uint64_t getDereferenceableBytes() const;
145
146  /// \brief Returns the number of dereferenceable_or_null bytes from the
147  /// dereferenceable_or_null attribute.
148  uint64_t getDereferenceableOrNullBytes() const;
149
150  /// \brief The Attribute is converted to a string of equivalent mnemonic. This
151  /// is, presumably, for writing out the mnemonics for the assembly writer.
152  std::string getAsString(bool InAttrGrp = false) const;
153
154  /// \brief Equality and non-equality operators.
155  bool operator==(Attribute A) const { return pImpl == A.pImpl; }
156  bool operator!=(Attribute A) const { return pImpl != A.pImpl; }
157
158  /// \brief Less-than operator. Useful for sorting the attributes list.
159  bool operator<(Attribute A) const;
160
161  void Profile(FoldingSetNodeID &ID) const {
162    ID.AddPointer(pImpl);
163  }
164};
165
166//===----------------------------------------------------------------------===//
167/// \class
168/// \brief This class holds the attributes for a function, its return value, and
169/// its parameters. You access the attributes for each of them via an index into
170/// the AttributeSet object. The function attributes are at index
171/// `AttributeSet::FunctionIndex', the return value is at index
172/// `AttributeSet::ReturnIndex', and the attributes for the parameters start at
173/// index `1'.
174class AttributeSet {
175public:
176  enum AttrIndex : unsigned {
177    ReturnIndex = 0U,
178    FunctionIndex = ~0U
179  };
180
181private:
182  friend class AttrBuilder;
183  friend class AttributeSetImpl;
184  template <typename Ty> friend struct DenseMapInfo;
185
186  /// \brief The attributes that we are managing. This can be null to represent
187  /// the empty attributes list.
188  AttributeSetImpl *pImpl;
189
190  /// \brief The attributes for the specified index are returned.
191  AttributeSetNode *getAttributes(unsigned Index) const;
192
193  /// \brief Create an AttributeSet with the specified parameters in it.
194  static AttributeSet get(LLVMContext &C,
195                          ArrayRef<std::pair<unsigned, Attribute> > Attrs);
196  static AttributeSet get(LLVMContext &C,
197                          ArrayRef<std::pair<unsigned,
198                                             AttributeSetNode*> > Attrs);
199
200  static AttributeSet getImpl(LLVMContext &C,
201                              ArrayRef<std::pair<unsigned,
202                                                 AttributeSetNode*> > Attrs);
203
204  explicit AttributeSet(AttributeSetImpl *LI) : pImpl(LI) {}
205
206public:
207  AttributeSet() : pImpl(nullptr) {}
208
209  //===--------------------------------------------------------------------===//
210  // AttributeSet Construction and Mutation
211  //===--------------------------------------------------------------------===//
212
213  /// \brief Return an AttributeSet with the specified parameters in it.
214  static AttributeSet get(LLVMContext &C, ArrayRef<AttributeSet> Attrs);
215  static AttributeSet get(LLVMContext &C, unsigned Index,
216                          ArrayRef<Attribute::AttrKind> Kind);
217  static AttributeSet get(LLVMContext &C, unsigned Index, const AttrBuilder &B);
218
219  /// \brief Add an attribute to the attribute set at the given index. Because
220  /// attribute sets are immutable, this returns a new set.
221  AttributeSet addAttribute(LLVMContext &C, unsigned Index,
222                            Attribute::AttrKind Attr) const;
223
224  /// \brief Add an attribute to the attribute set at the given index. Because
225  /// attribute sets are immutable, this returns a new set.
226  AttributeSet addAttribute(LLVMContext &C, unsigned Index,
227                            StringRef Kind) const;
228  AttributeSet addAttribute(LLVMContext &C, unsigned Index,
229                            StringRef Kind, StringRef Value) const;
230
231  /// Add an attribute to the attribute set at the given indices. Because
232  /// attribute sets are immutable, this returns a new set.
233  AttributeSet addAttribute(LLVMContext &C, ArrayRef<unsigned> Indices,
234                            Attribute A) const;
235
236  /// \brief Add attributes to the attribute set at the given index. Because
237  /// attribute sets are immutable, this returns a new set.
238  AttributeSet addAttributes(LLVMContext &C, unsigned Index,
239                             AttributeSet Attrs) const;
240
241  /// \brief Remove the specified attribute at the specified index from this
242  /// attribute list. Because attribute lists are immutable, this returns the
243  /// new list.
244  AttributeSet removeAttribute(LLVMContext &C, unsigned Index,
245                               Attribute::AttrKind Attr) const;
246
247  /// \brief Remove the specified attributes at the specified index from this
248  /// attribute list. Because attribute lists are immutable, this returns the
249  /// new list.
250  AttributeSet removeAttributes(LLVMContext &C, unsigned Index,
251                                AttributeSet Attrs) const;
252
253  /// \brief Remove the specified attributes at the specified index from this
254  /// attribute list. Because attribute lists are immutable, this returns the
255  /// new list.
256  AttributeSet removeAttributes(LLVMContext &C, unsigned Index,
257                                const AttrBuilder &Attrs) const;
258
259  /// \brief Add the dereferenceable attribute to the attribute set at the given
260  /// index. Because attribute sets are immutable, this returns a new set.
261  AttributeSet addDereferenceableAttr(LLVMContext &C, unsigned Index,
262                                      uint64_t Bytes) const;
263
264  /// \brief Add the dereferenceable_or_null attribute to the attribute set at
265  /// the given index. Because attribute sets are immutable, this returns a new
266  /// set.
267  AttributeSet addDereferenceableOrNullAttr(LLVMContext &C, unsigned Index,
268                                            uint64_t Bytes) const;
269
270  //===--------------------------------------------------------------------===//
271  // AttributeSet Accessors
272  //===--------------------------------------------------------------------===//
273
274  /// \brief Retrieve the LLVM context.
275  LLVMContext &getContext() const;
276
277  /// \brief The attributes for the specified index are returned.
278  AttributeSet getParamAttributes(unsigned Index) const;
279
280  /// \brief The attributes for the ret value are returned.
281  AttributeSet getRetAttributes() const;
282
283  /// \brief The function attributes are returned.
284  AttributeSet getFnAttributes() const;
285
286  /// \brief Return true if the attribute exists at the given index.
287  bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
288
289  /// \brief Return true if the attribute exists at the given index.
290  bool hasAttribute(unsigned Index, StringRef Kind) const;
291
292  /// \brief Return true if attribute exists at the given index.
293  bool hasAttributes(unsigned Index) const;
294
295  /// \brief Return true if the specified attribute is set for at least one
296  /// parameter or for the return value.
297  bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
298
299  /// \brief Return the attribute object that exists at the given index.
300  Attribute getAttribute(unsigned Index, Attribute::AttrKind Kind) const;
301
302  /// \brief Return the attribute object that exists at the given index.
303  Attribute getAttribute(unsigned Index, StringRef Kind) const;
304
305  /// \brief Return the alignment for the specified function parameter.
306  unsigned getParamAlignment(unsigned Index) const;
307
308  /// \brief Get the stack alignment.
309  unsigned getStackAlignment(unsigned Index) const;
310
311  /// \brief Get the number of dereferenceable bytes (or zero if unknown).
312  uint64_t getDereferenceableBytes(unsigned Index) const;
313
314  /// \brief Get the number of dereferenceable_or_null bytes (or zero if
315  /// unknown).
316  uint64_t getDereferenceableOrNullBytes(unsigned Index) const;
317
318  /// \brief Return the attributes at the index as a string.
319  std::string getAsString(unsigned Index, bool InAttrGrp = false) const;
320
321  typedef ArrayRef<Attribute>::iterator iterator;
322
323  iterator begin(unsigned Slot) const;
324  iterator end(unsigned Slot) const;
325
326  /// operator==/!= - Provide equality predicates.
327  bool operator==(const AttributeSet &RHS) const {
328    return pImpl == RHS.pImpl;
329  }
330  bool operator!=(const AttributeSet &RHS) const {
331    return pImpl != RHS.pImpl;
332  }
333
334  //===--------------------------------------------------------------------===//
335  // AttributeSet Introspection
336  //===--------------------------------------------------------------------===//
337
338  // FIXME: Remove this.
339  uint64_t Raw(unsigned Index) const;
340
341  /// \brief Return a raw pointer that uniquely identifies this attribute list.
342  void *getRawPointer() const {
343    return pImpl;
344  }
345
346  /// \brief Return true if there are no attributes.
347  bool isEmpty() const {
348    return getNumSlots() == 0;
349  }
350
351  /// \brief Return the number of slots used in this attribute list.  This is
352  /// the number of arguments that have an attribute set on them (including the
353  /// function itself).
354  unsigned getNumSlots() const;
355
356  /// \brief Return the index for the given slot.
357  unsigned getSlotIndex(unsigned Slot) const;
358
359  /// \brief Return the attributes at the given slot.
360  AttributeSet getSlotAttributes(unsigned Slot) const;
361
362  void dump() const;
363};
364
365//===----------------------------------------------------------------------===//
366/// \class
367/// \brief Provide DenseMapInfo for AttributeSet.
368template<> struct DenseMapInfo<AttributeSet> {
369  static inline AttributeSet getEmptyKey() {
370    uintptr_t Val = static_cast<uintptr_t>(-1);
371    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
372    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
373  }
374  static inline AttributeSet getTombstoneKey() {
375    uintptr_t Val = static_cast<uintptr_t>(-2);
376    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
377    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
378  }
379  static unsigned getHashValue(AttributeSet AS) {
380    return (unsigned((uintptr_t)AS.pImpl) >> 4) ^
381           (unsigned((uintptr_t)AS.pImpl) >> 9);
382  }
383  static bool isEqual(AttributeSet LHS, AttributeSet RHS) { return LHS == RHS; }
384};
385
386//===----------------------------------------------------------------------===//
387/// \class
388/// \brief This class is used in conjunction with the Attribute::get method to
389/// create an Attribute object. The object itself is uniquified. The Builder's
390/// value, however, is not. So this can be used as a quick way to test for
391/// equality, presence of attributes, etc.
392class AttrBuilder {
393  std::bitset<Attribute::EndAttrKinds> Attrs;
394  std::map<std::string, std::string> TargetDepAttrs;
395  uint64_t Alignment;
396  uint64_t StackAlignment;
397  uint64_t DerefBytes;
398  uint64_t DerefOrNullBytes;
399
400public:
401  AttrBuilder()
402      : Attrs(0), Alignment(0), StackAlignment(0), DerefBytes(0),
403        DerefOrNullBytes(0) {}
404  explicit AttrBuilder(uint64_t Val)
405      : Attrs(0), Alignment(0), StackAlignment(0), DerefBytes(0),
406        DerefOrNullBytes(0) {
407    addRawValue(Val);
408  }
409  AttrBuilder(const Attribute &A)
410      : Attrs(0), Alignment(0), StackAlignment(0), DerefBytes(0),
411        DerefOrNullBytes(0) {
412    addAttribute(A);
413  }
414  AttrBuilder(AttributeSet AS, unsigned Idx);
415
416  void clear();
417
418  /// \brief Add an attribute to the builder.
419  AttrBuilder &addAttribute(Attribute::AttrKind Val);
420
421  /// \brief Add the Attribute object to the builder.
422  AttrBuilder &addAttribute(Attribute A);
423
424  /// \brief Add the target-dependent attribute to the builder.
425  AttrBuilder &addAttribute(StringRef A, StringRef V = StringRef());
426
427  /// \brief Remove an attribute from the builder.
428  AttrBuilder &removeAttribute(Attribute::AttrKind Val);
429
430  /// \brief Remove the attributes from the builder.
431  AttrBuilder &removeAttributes(AttributeSet A, uint64_t Index);
432
433  /// \brief Remove the target-dependent attribute to the builder.
434  AttrBuilder &removeAttribute(StringRef A);
435
436  /// \brief Add the attributes from the builder.
437  AttrBuilder &merge(const AttrBuilder &B);
438
439  /// \brief Remove the attributes from the builder.
440  AttrBuilder &remove(const AttrBuilder &B);
441
442  /// \brief Return true if the builder has any attribute that's in the
443  /// specified builder.
444  bool overlaps(const AttrBuilder &B) const;
445
446  /// \brief Return true if the builder has the specified attribute.
447  bool contains(Attribute::AttrKind A) const {
448    assert((unsigned)A < Attribute::EndAttrKinds && "Attribute out of range!");
449    return Attrs[A];
450  }
451
452  /// \brief Return true if the builder has the specified target-dependent
453  /// attribute.
454  bool contains(StringRef A) const;
455
456  /// \brief Return true if the builder has IR-level attributes.
457  bool hasAttributes() const;
458
459  /// \brief Return true if the builder has any attribute that's in the
460  /// specified attribute.
461  bool hasAttributes(AttributeSet A, uint64_t Index) const;
462
463  /// \brief Return true if the builder has an alignment attribute.
464  bool hasAlignmentAttr() const;
465
466  /// \brief Retrieve the alignment attribute, if it exists.
467  uint64_t getAlignment() const { return Alignment; }
468
469  /// \brief Retrieve the stack alignment attribute, if it exists.
470  uint64_t getStackAlignment() const { return StackAlignment; }
471
472  /// \brief Retrieve the number of dereferenceable bytes, if the
473  /// dereferenceable attribute exists (zero is returned otherwise).
474  uint64_t getDereferenceableBytes() const { return DerefBytes; }
475
476  /// \brief Retrieve the number of dereferenceable_or_null bytes, if the
477  /// dereferenceable_or_null attribute exists (zero is returned otherwise).
478  uint64_t getDereferenceableOrNullBytes() const { return DerefOrNullBytes; }
479
480  /// \brief This turns an int alignment (which must be a power of 2) into the
481  /// form used internally in Attribute.
482  AttrBuilder &addAlignmentAttr(unsigned Align);
483
484  /// \brief This turns an int stack alignment (which must be a power of 2) into
485  /// the form used internally in Attribute.
486  AttrBuilder &addStackAlignmentAttr(unsigned Align);
487
488  /// \brief This turns the number of dereferenceable bytes into the form used
489  /// internally in Attribute.
490  AttrBuilder &addDereferenceableAttr(uint64_t Bytes);
491
492  /// \brief This turns the number of dereferenceable_or_null bytes into the
493  /// form used internally in Attribute.
494  AttrBuilder &addDereferenceableOrNullAttr(uint64_t Bytes);
495
496  /// \brief Return true if the builder contains no target-independent
497  /// attributes.
498  bool empty() const { return Attrs.none(); }
499
500  // Iterators for target-dependent attributes.
501  typedef std::pair<std::string, std::string>                td_type;
502  typedef std::map<std::string, std::string>::iterator       td_iterator;
503  typedef std::map<std::string, std::string>::const_iterator td_const_iterator;
504  typedef llvm::iterator_range<td_iterator>                  td_range;
505  typedef llvm::iterator_range<td_const_iterator>            td_const_range;
506
507  td_iterator td_begin()             { return TargetDepAttrs.begin(); }
508  td_iterator td_end()               { return TargetDepAttrs.end(); }
509
510  td_const_iterator td_begin() const { return TargetDepAttrs.begin(); }
511  td_const_iterator td_end() const   { return TargetDepAttrs.end(); }
512
513  td_range td_attrs() { return td_range(td_begin(), td_end()); }
514  td_const_range td_attrs() const {
515    return td_const_range(td_begin(), td_end());
516  }
517
518  bool td_empty() const              { return TargetDepAttrs.empty(); }
519
520  bool operator==(const AttrBuilder &B);
521  bool operator!=(const AttrBuilder &B) {
522    return !(*this == B);
523  }
524
525  // FIXME: Remove this in 4.0.
526
527  /// \brief Add the raw value to the internal representation.
528  AttrBuilder &addRawValue(uint64_t Val);
529};
530
531namespace AttributeFuncs {
532
533/// \brief Which attributes cannot be applied to a type.
534AttrBuilder typeIncompatible(Type *Ty);
535
536/// \returns Return true if the two functions have compatible target-independent
537/// attributes for inlining purposes.
538bool areInlineCompatible(const Function &Caller, const Function &Callee);
539
540/// \brief Merge caller's and callee's attributes.
541void mergeAttributesForInlining(Function &Caller, const Function &Callee);
542
543} // end AttributeFuncs namespace
544
545} // end llvm namespace
546
547#endif
548