Attributes.h revision b29ce26ea60f7516c853318ffbfc107fde9ad897 
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/DenseSet.h"
21#include "llvm/ADT/FoldingSet.h"
22#include <cassert>
23#include <map>
24#include <string>
25
26namespace llvm {
27
28class AttrBuilder;
29class AttributeImpl;
30class AttributeSetImpl;
31class AttributeSetNode;
32class Constant;
33class LLVMContext;
34class Type;
35
36//===----------------------------------------------------------------------===//
37/// \class
38/// \brief Functions, function parameters, and return types can have attributes
39/// to indicate how they should be treated by optimizations and code
40/// generation. This class represents one of those attributes. It's light-weight
41/// and should be passed around by-value.
42class Attribute {
43public:
44  /// This enumeration lists the attributes that can be associated with
45  /// parameters, function results, or the function itself.
46  ///
47  /// Note: The `uwtable' attribute is about the ABI or the user mandating an
48  /// entry in the unwind table. The `nounwind' attribute is about an exception
49  /// passing by the function.
50  ///
51  /// In a theoretical system that uses tables for profiling and SjLj for
52  /// exceptions, they would be fully independent. In a normal system that uses
53  /// tables for both, the semantics are:
54  ///
55  /// nil                = Needs an entry because an exception might pass by.
56  /// nounwind           = No need for an entry
57  /// uwtable            = Needs an entry because the ABI says so and because
58  ///                      an exception might pass by.
59  /// uwtable + nounwind = Needs an entry because the ABI says so.
60
61  enum AttrKind {
62    // IR-Level Attributes
63    None,                  ///< No attributes have been set
64    AddressSafety,         ///< Address safety checking is on.
65    Alignment,             ///< Alignment of parameter (5 bits)
66                           ///< stored as log2 of alignment with +1 bias
67                           ///< 0 means unaligned (different from align(1))
68    AlwaysInline,          ///< inline=always
69    ByVal,                 ///< Pass structure by value
70    InlineHint,            ///< Source said inlining was desirable
71    InReg,                 ///< Force argument to be passed in register
72    MinSize,               ///< Function must be optimized for size first
73    Naked,                 ///< Naked function
74    Nest,                  ///< Nested function static chain
75    NoAlias,               ///< Considered to not alias after call
76    NoCapture,             ///< Function creates no aliases of pointer
77    NoDuplicate,           ///< Call cannot be duplicated
78    NoImplicitFloat,       ///< Disable implicit floating point insts
79    NoInline,              ///< inline=never
80    NonLazyBind,           ///< Function is called early and/or
81                           ///< often, so lazy binding isn't worthwhile
82    NoRedZone,             ///< Disable redzone
83    NoReturn,              ///< Mark the function as not returning
84    NoUnwind,              ///< Function doesn't unwind stack
85    OptimizeForSize,       ///< opt_size
86    ReadNone,              ///< Function does not access memory
87    ReadOnly,              ///< Function only reads from memory
88    ReturnsTwice,          ///< Function can return twice
89    SExt,                  ///< Sign extended before/after call
90    StackAlignment,        ///< Alignment of stack for function (3 bits)
91                           ///< stored as log2 of alignment with +1 bias 0
92                           ///< means unaligned (different from
93                           ///< alignstack=(1))
94    StackProtect,          ///< Stack protection.
95    StackProtectReq,       ///< Stack protection required.
96    StackProtectStrong,    ///< Strong Stack protection.
97    StructRet,             ///< Hidden pointer to structure to return
98    ThreadSafety,          ///< Thread safety checking is on.
99    UninitializedChecks,   ///< Checking for uses of uninitialized memory is on.
100    UWTable,               ///< Function must be in a unwind table
101    ZExt,                  ///< Zero extended before/after call
102
103    EndAttrKinds,          ///< Sentinal value useful for loops
104
105    AttrKindEmptyKey,      ///< Empty key value for DenseMapInfo
106    AttrKindTombstoneKey   ///< Tombstone key value for DenseMapInfo
107  };
108private:
109  AttributeImpl *pImpl;
110  Attribute(AttributeImpl *A) : pImpl(A) {}
111public:
112  Attribute() : pImpl(0) {}
113
114  //===--------------------------------------------------------------------===//
115  // Attribute Construction
116  //===--------------------------------------------------------------------===//
117
118  /// \brief Return a uniquified Attribute object.
119  static Attribute get(LLVMContext &Context, AttrKind Kind, uint64_t Val = 0);
120  static Attribute get(LLVMContext &Context, StringRef Kind,
121                       StringRef Val = StringRef());
122
123  /// \brief Return a uniquified Attribute object that has the specific
124  /// alignment set.
125  static Attribute getWithAlignment(LLVMContext &Context, uint64_t Align);
126  static Attribute getWithStackAlignment(LLVMContext &Context, uint64_t Align);
127
128  //===--------------------------------------------------------------------===//
129  // Attribute Accessors
130  //===--------------------------------------------------------------------===//
131
132  /// \brief Return true if the attribute is an Attribute::AttrKind type.
133  bool isEnumAttribute() const;
134
135  /// \brief Return true if the attribute is an alignment attribute.
136  bool isAlignAttribute() const;
137
138  /// \brief Return true if the attribute is a string (target-dependent)
139  /// attribute.
140  bool isStringAttribute() const;
141
142  /// \brief Return true if the attribute is present.
143  bool hasAttribute(AttrKind Val) const;
144
145  /// \brief Return true if the target-dependent attribute is present.
146  bool hasAttribute(StringRef Val) const;
147
148  /// \brief Return the attribute's kind as an enum (Attribute::AttrKind). This
149  /// requires the attribute to be an enum or alignment attribute.
150  Attribute::AttrKind getKindAsEnum() const;
151
152  /// \brief Return the attribute's value as an integer. This requires that the
153  /// attribute be an alignment attribute.
154  uint64_t getValueAsInt() const;
155
156  /// \brief Return the attribute's kind as a string. This requires the
157  /// attribute to be a string attribute.
158  StringRef getKindAsString() const;
159
160  /// \brief Return the attribute's value as a string. This requires the
161  /// attribute to be a string attribute.
162  StringRef getValueAsString() const;
163
164  /// \brief Returns the alignment field of an attribute as a byte alignment
165  /// value.
166  unsigned getAlignment() const;
167
168  /// \brief Returns the stack alignment field of an attribute as a byte
169  /// alignment value.
170  unsigned getStackAlignment() const;
171
172  /// \brief The Attribute is converted to a string of equivalent mnemonic. This
173  /// is, presumably, for writing out the mnemonics for the assembly writer.
174  std::string getAsString(bool InAttrGrp = false) const;
175
176  /// \brief Equality and non-equality operators.
177  bool operator==(Attribute A) const { return pImpl == A.pImpl; }
178  bool operator!=(Attribute A) const { return pImpl != A.pImpl; }
179
180  /// \brief Less-than operator. Useful for sorting the attributes list.
181  bool operator<(Attribute A) const;
182
183  void Profile(FoldingSetNodeID &ID) const {
184    ID.AddPointer(pImpl);
185  }
186};
187
188//===----------------------------------------------------------------------===//
189/// \class
190/// \brief Provide DenseMapInfo for Attribute::AttrKinds. This is used by
191/// AttrBuilder.
192template<> struct DenseMapInfo<Attribute::AttrKind> {
193  static inline Attribute::AttrKind getEmptyKey() {
194    return Attribute::AttrKindEmptyKey;
195  }
196  static inline Attribute::AttrKind getTombstoneKey() {
197    return Attribute::AttrKindTombstoneKey;
198  }
199  static unsigned getHashValue(const Attribute::AttrKind &Val) {
200    return Val * 37U;
201  }
202  static bool isEqual(const Attribute::AttrKind &LHS,
203                      const Attribute::AttrKind &RHS) {
204    return LHS == RHS;
205  }
206};
207
208//===----------------------------------------------------------------------===//
209/// \class
210/// \brief This class holds the attributes for a function, its return value, and
211/// its parameters. You access the attributes for each of them via an index into
212/// the AttributeSet object. The function attributes are at index
213/// `AttributeSet::FunctionIndex', the return value is at index
214/// `AttributeSet::ReturnIndex', and the attributes for the parameters start at
215/// index `1'.
216class AttributeSet {
217public:
218  enum AttrIndex {
219    ReturnIndex = 0U,
220    FunctionIndex = ~0U
221  };
222private:
223  friend class AttrBuilder;
224  friend class AttributeSetImpl;
225  template <typename Ty> friend struct DenseMapInfo;
226
227  /// \brief The attributes that we are managing. This can be null to represent
228  /// the empty attributes list.
229  AttributeSetImpl *pImpl;
230
231  /// \brief The attributes for the specified index are returned.
232  AttributeSetNode *getAttributes(unsigned Idx) const;
233
234  /// \brief Create an AttributeSet with the specified parameters in it.
235  static AttributeSet get(LLVMContext &C,
236                          ArrayRef<std::pair<unsigned, Attribute> > Attrs);
237  static AttributeSet get(LLVMContext &C,
238                          ArrayRef<std::pair<unsigned,
239                                             AttributeSetNode*> > Attrs);
240
241  static AttributeSet getImpl(LLVMContext &C,
242                              ArrayRef<std::pair<unsigned,
243                                                 AttributeSetNode*> > Attrs);
244
245
246  explicit AttributeSet(AttributeSetImpl *LI) : pImpl(LI) {}
247public:
248  AttributeSet() : pImpl(0) {}
249  AttributeSet(const AttributeSet &P) : pImpl(P.pImpl) {}
250  const AttributeSet &operator=(const AttributeSet &RHS) {
251    pImpl = RHS.pImpl;
252    return *this;
253  }
254
255  //===--------------------------------------------------------------------===//
256  // AttributeSet Construction and Mutation
257  //===--------------------------------------------------------------------===//
258
259  /// \brief Return an AttributeSet with the specified parameters in it.
260  static AttributeSet get(LLVMContext &C, ArrayRef<AttributeSet> Attrs);
261  static AttributeSet get(LLVMContext &C, unsigned Idx,
262                          ArrayRef<Attribute::AttrKind> Kind);
263  static AttributeSet get(LLVMContext &C, unsigned Idx, AttrBuilder &B);
264
265  /// \brief Add an attribute to the attribute set at the given index. Since
266  /// attribute sets are immutable, this returns a new set.
267  AttributeSet addAttribute(LLVMContext &C, unsigned Idx,
268                            Attribute::AttrKind Attr) const;
269
270  /// \brief Add attributes to the attribute set at the given index. Since
271  /// attribute sets are immutable, this returns a new set.
272  AttributeSet addAttributes(LLVMContext &C, unsigned Idx,
273                             AttributeSet Attrs) const;
274
275  /// \brief Remove the specified attribute at the specified index from this
276  /// attribute list. Since attribute lists are immutable, this returns the new
277  /// list.
278  AttributeSet removeAttribute(LLVMContext &C, unsigned Idx,
279                               Attribute::AttrKind Attr) const;
280
281  /// \brief Remove the specified attributes at the specified index from this
282  /// attribute list. Since attribute lists are immutable, this returns the new
283  /// list.
284  AttributeSet removeAttributes(LLVMContext &C, unsigned Idx,
285                                AttributeSet Attrs) const;
286
287  //===--------------------------------------------------------------------===//
288  // AttributeSet Accessors
289  //===--------------------------------------------------------------------===//
290
291  /// \brief Retrieve the LLVM context.
292  LLVMContext &getContext() const;
293
294  /// \brief The attributes for the specified index are returned.
295  AttributeSet getParamAttributes(unsigned Idx) const;
296
297  /// \brief The attributes for the ret value are returned.
298  AttributeSet getRetAttributes() const;
299
300  /// \brief The function attributes are returned.
301  AttributeSet getFnAttributes() const;
302
303  /// \brief Return true if the attribute exists at the given index.
304  bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
305
306  /// \brief Return true if attribute exists at the given index.
307  bool hasAttributes(unsigned Index) const;
308
309  /// \brief Return true if the specified attribute is set for at least one
310  /// parameter or for the return value.
311  bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
312
313  /// \brief Return the alignment for the specified function parameter.
314  unsigned getParamAlignment(unsigned Idx) const;
315
316  /// \brief Get the stack alignment.
317  unsigned getStackAlignment(unsigned Index) const;
318
319  /// \brief Return the attributes at the index as a string.
320  std::string getAsString(unsigned Index, bool InAttrGrp = false) const;
321
322  typedef ArrayRef<Attribute>::iterator iterator;
323
324  iterator begin(unsigned Idx) const;
325  iterator end(unsigned Idx) const;
326
327  /// operator==/!= - Provide equality predicates.
328  bool operator==(const AttributeSet &RHS) const {
329    return pImpl == RHS.pImpl;
330  }
331  bool operator!=(const AttributeSet &RHS) const {
332    return pImpl != RHS.pImpl;
333  }
334
335  //===--------------------------------------------------------------------===//
336  // AttributeSet Introspection
337  //===--------------------------------------------------------------------===//
338
339  // FIXME: Remove this.
340  uint64_t Raw(unsigned Index) const;
341
342  /// \brief Return a raw pointer that uniquely identifies this attribute list.
343  void *getRawPointer() const {
344    return pImpl;
345  }
346
347  /// \brief Return true if there are no attributes.
348  bool isEmpty() const {
349    return getNumSlots() == 0;
350  }
351
352  /// \brief Return the number of slots used in this attribute list.  This is
353  /// the number of arguments that have an attribute set on them (including the
354  /// function itself).
355  unsigned getNumSlots() const;
356
357  /// \brief Return the index for the given slot.
358  uint64_t getSlotIndex(unsigned Slot) const;
359
360  /// \brief Return the attributes at the given slot.
361  AttributeSet getSlotAttributes(unsigned Slot) const;
362
363  void dump() const;
364};
365
366//===----------------------------------------------------------------------===//
367/// \class
368/// \brief Provide DenseMapInfo for AttributeSet.
369template<> struct DenseMapInfo<AttributeSet> {
370  static inline AttributeSet getEmptyKey() {
371    uintptr_t Val = static_cast<uintptr_t>(-1);
372    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
373    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
374  }
375  static inline AttributeSet getTombstoneKey() {
376    uintptr_t Val = static_cast<uintptr_t>(-2);
377    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
378    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
379  }
380  static unsigned getHashValue(AttributeSet AS) {
381    return (unsigned((uintptr_t)AS.pImpl) >> 4) ^
382           (unsigned((uintptr_t)AS.pImpl) >> 9);
383  }
384  static bool isEqual(AttributeSet LHS, AttributeSet RHS) { return LHS == RHS; }
385};
386
387//===----------------------------------------------------------------------===//
388/// \class
389/// \brief This class is used in conjunction with the Attribute::get method to
390/// create an Attribute object. The object itself is uniquified. The Builder's
391/// value, however, is not. So this can be used as a quick way to test for
392/// equality, presence of attributes, etc.
393class AttrBuilder {
394  DenseSet<Attribute::AttrKind> Attrs;
395  std::map<std::string, std::string> TargetDepAttrs;
396  uint64_t Alignment;
397  uint64_t StackAlignment;
398public:
399  AttrBuilder() : Alignment(0), StackAlignment(0) {}
400  explicit AttrBuilder(uint64_t Val) : Alignment(0), StackAlignment(0) {
401    addRawValue(Val);
402  }
403  AttrBuilder(const Attribute &A) : Alignment(0), StackAlignment(0) {
404    addAttribute(A);
405  }
406  AttrBuilder(AttributeSet AS, unsigned Idx);
407  AttrBuilder(const AttrBuilder &B)
408    : Attrs(B.Attrs),
409      TargetDepAttrs(B.TargetDepAttrs.begin(), B.TargetDepAttrs.end()),
410      Alignment(B.Alignment), StackAlignment(B.StackAlignment) {}
411
412  void clear();
413
414  /// \brief Add an attribute to the builder.
415  AttrBuilder &addAttribute(Attribute::AttrKind Val);
416
417  /// \brief Add the Attribute object to the builder.
418  AttrBuilder &addAttribute(Attribute A);
419
420  /// \brief Add the target-dependent attribute to the builder.
421  AttrBuilder &addAttribute(StringRef A, StringRef V);
422
423  /// \brief Remove an attribute from the builder.
424  AttrBuilder &removeAttribute(Attribute::AttrKind Val);
425
426  /// \brief Remove the attributes from the builder.
427  AttrBuilder &removeAttributes(AttributeSet A, uint64_t Index);
428
429  /// \brief Remove the target-dependent attribute to the builder.
430  AttrBuilder &removeAttribute(StringRef A);
431
432  /// \brief Add the attributes from the builder.
433  AttrBuilder &merge(const AttrBuilder &B);
434
435  /// \brief Return true if the builder has the specified attribute.
436  bool contains(Attribute::AttrKind A) const;
437
438  /// \brief Return true if the builder has the specified target-dependent
439  /// attribute.
440  bool contains(StringRef A) const;
441
442  /// \brief Return true if the builder has IR-level attributes.
443  bool hasAttributes() const;
444
445  /// \brief Return true if the builder has any attribute that's in the
446  /// specified attribute.
447  bool hasAttributes(AttributeSet A, uint64_t Index) const;
448
449  /// \brief Return true if the builder has an alignment attribute.
450  bool hasAlignmentAttr() const;
451
452  /// \brief Retrieve the alignment attribute, if it exists.
453  uint64_t getAlignment() const { return Alignment; }
454
455  /// \brief Retrieve the stack alignment attribute, if it exists.
456  uint64_t getStackAlignment() const { return StackAlignment; }
457
458  /// \brief This turns an int alignment (which must be a power of 2) into the
459  /// form used internally in Attribute.
460  AttrBuilder &addAlignmentAttr(unsigned Align);
461
462  /// \brief This turns an int stack alignment (which must be a power of 2) into
463  /// the form used internally in Attribute.
464  AttrBuilder &addStackAlignmentAttr(unsigned Align);
465
466  // Iterators for target-independent attributes.
467  typedef DenseSet<Attribute::AttrKind>::iterator       iterator;
468  typedef DenseSet<Attribute::AttrKind>::const_iterator const_iterator;
469
470  iterator begin()             { return Attrs.begin(); }
471  iterator end()               { return Attrs.end(); }
472
473  const_iterator begin() const { return Attrs.begin(); }
474  const_iterator end() const   { return Attrs.end(); }
475
476  bool empty() const           { return Attrs.empty(); }
477
478  // Iterators for target-dependent attributes.
479  typedef std::pair<std::string, std::string>                td_type;
480  typedef std::map<std::string, std::string>::iterator       td_iterator;
481  typedef std::map<std::string, std::string>::const_iterator td_const_iterator;
482
483  td_iterator td_begin()             { return TargetDepAttrs.begin(); }
484  td_iterator td_end()               { return TargetDepAttrs.end(); }
485
486  td_const_iterator td_begin() const { return TargetDepAttrs.begin(); }
487  td_const_iterator td_end() const   { return TargetDepAttrs.end(); }
488
489  bool td_empty() const              { return TargetDepAttrs.empty(); }
490
491  /// \brief Remove attributes that are used on functions only.
492  void removeFunctionOnlyAttrs() {
493    removeAttribute(Attribute::NoReturn)
494      .removeAttribute(Attribute::NoUnwind)
495      .removeAttribute(Attribute::ReadNone)
496      .removeAttribute(Attribute::ReadOnly)
497      .removeAttribute(Attribute::NoInline)
498      .removeAttribute(Attribute::AlwaysInline)
499      .removeAttribute(Attribute::OptimizeForSize)
500      .removeAttribute(Attribute::StackProtect)
501      .removeAttribute(Attribute::StackProtectReq)
502      .removeAttribute(Attribute::StackProtectStrong)
503      .removeAttribute(Attribute::NoRedZone)
504      .removeAttribute(Attribute::NoImplicitFloat)
505      .removeAttribute(Attribute::Naked)
506      .removeAttribute(Attribute::InlineHint)
507      .removeAttribute(Attribute::StackAlignment)
508      .removeAttribute(Attribute::UWTable)
509      .removeAttribute(Attribute::NonLazyBind)
510      .removeAttribute(Attribute::ReturnsTwice)
511      .removeAttribute(Attribute::AddressSafety)
512      .removeAttribute(Attribute::ThreadSafety)
513      .removeAttribute(Attribute::UninitializedChecks)
514      .removeAttribute(Attribute::MinSize)
515      .removeAttribute(Attribute::NoDuplicate);
516  }
517
518  bool operator==(const AttrBuilder &B);
519  bool operator!=(const AttrBuilder &B) {
520    return !(*this == B);
521  }
522
523  // FIXME: Remove this in 4.0.
524
525  /// \brief Add the raw value to the internal representation.
526  AttrBuilder &addRawValue(uint64_t Val);
527};
528
529namespace AttributeFuncs {
530
531/// \brief Which attributes cannot be applied to a type.
532AttributeSet typeIncompatible(Type *Ty, uint64_t Index);
533
534} // end AttributeFuncs namespace
535
536} // end llvm namespace
537
538#endif
539