Attributes.h revision bb1b63c48397a3bac5d00f2ac9d33cc14efd714c 
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/PointerLikeTypeTraits.h"
22#include <bitset>
23#include <cassert>
24#include <map>
25#include <string>
26
27namespace llvm {
28
29class AttrBuilder;
30class AttributeImpl;
31class AttributeSetImpl;
32class AttributeSetNode;
33class Constant;
34template<typename T> struct DenseMapInfo;
35class LLVMContext;
36class Type;
37
38//===----------------------------------------------------------------------===//
39/// \class
40/// \brief Functions, function parameters, and return types can have attributes
41/// to indicate how they should be treated by optimizations and code
42/// generation. This class represents one of those attributes. It's light-weight
43/// and should be passed around by-value.
44class Attribute {
45public:
46  /// This enumeration lists the attributes that can be associated with
47  /// parameters, function results, or the function itself.
48  ///
49  /// Note: The `uwtable' attribute is about the ABI or the user mandating an
50  /// entry in the unwind table. The `nounwind' attribute is about an exception
51  /// passing by the function.
52  ///
53  /// In a theoretical system that uses tables for profiling and SjLj for
54  /// exceptions, they would be fully independent. In a normal system that uses
55  /// tables for both, the semantics are:
56  ///
57  /// nil                = Needs an entry because an exception might pass by.
58  /// nounwind           = No need for an entry
59  /// uwtable            = Needs an entry because the ABI says so and because
60  ///                      an exception might pass by.
61  /// uwtable + nounwind = Needs an entry because the ABI says so.
62
63  enum AttrKind {
64    // IR-Level Attributes
65    None,                  ///< No attributes have been set
66    Alignment,             ///< Alignment of parameter (5 bits)
67                           ///< stored as log2 of alignment with +1 bias
68                           ///< 0 means unaligned (different from align(1))
69    AlwaysInline,          ///< inline=always
70    ByVal,                 ///< Pass structure by value
71    InlineHint,            ///< Source said inlining was desirable
72    InReg,                 ///< Force argument to be passed in register
73    MinSize,               ///< Function must be optimized for size first
74    Naked,                 ///< Naked function
75    Nest,                  ///< Nested function static chain
76    NoAlias,               ///< Considered to not alias after call
77    NoBuiltin,             ///< Callee isn't recognized as a builtin
78    NoCapture,             ///< Function creates no aliases of pointer
79    NoDuplicate,           ///< Call cannot be duplicated
80    NoImplicitFloat,       ///< Disable implicit floating point insts
81    NoInline,              ///< inline=never
82    NonLazyBind,           ///< Function is called early and/or
83                           ///< often, so lazy binding isn't worthwhile
84    NoRedZone,             ///< Disable redzone
85    NoReturn,              ///< Mark the function as not returning
86    NoUnwind,              ///< Function doesn't unwind stack
87    OptimizeForSize,       ///< opt_size
88    ReadNone,              ///< Function does not access memory
89    ReadOnly,              ///< Function only reads from memory
90    ReturnsTwice,          ///< Function can return twice
91    SExt,                  ///< Sign extended before/after call
92    StackAlignment,        ///< Alignment of stack for function (3 bits)
93                           ///< stored as log2 of alignment with +1 bias 0
94                           ///< means unaligned (different from
95                           ///< alignstack=(1))
96    StackProtect,          ///< Stack protection.
97    StackProtectReq,       ///< Stack protection required.
98    StackProtectStrong,    ///< Strong Stack protection.
99    StructRet,             ///< Hidden pointer to structure to return
100    SanitizeAddress,       ///< AddressSanitizer is on.
101    SanitizeThread,        ///< ThreadSanitizer is on.
102    SanitizeMemory,        ///< MemorySanitizer is on.
103    UWTable,               ///< Function must be in a unwind table
104    ZExt,                  ///< Zero extended before/after call
105
106    EndAttrKinds           ///< Sentinal value useful for loops
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 This class holds the attributes for a function, its return value, and
191/// its parameters. You access the attributes for each of them via an index into
192/// the AttributeSet object. The function attributes are at index
193/// `AttributeSet::FunctionIndex', the return value is at index
194/// `AttributeSet::ReturnIndex', and the attributes for the parameters start at
195/// index `1'.
196class AttributeSet {
197public:
198  enum AttrIndex {
199    ReturnIndex = 0U,
200    FunctionIndex = ~0U
201  };
202private:
203  friend class AttrBuilder;
204  friend class AttributeSetImpl;
205  template <typename Ty> friend struct DenseMapInfo;
206
207  /// \brief The attributes that we are managing. This can be null to represent
208  /// the empty attributes list.
209  AttributeSetImpl *pImpl;
210
211  /// \brief The attributes for the specified index are returned.
212  AttributeSetNode *getAttributes(unsigned Idx) const;
213
214  /// \brief Create an AttributeSet with the specified parameters in it.
215  static AttributeSet get(LLVMContext &C,
216                          ArrayRef<std::pair<unsigned, Attribute> > Attrs);
217  static AttributeSet get(LLVMContext &C,
218                          ArrayRef<std::pair<unsigned,
219                                             AttributeSetNode*> > Attrs);
220
221  static AttributeSet getImpl(LLVMContext &C,
222                              ArrayRef<std::pair<unsigned,
223                                                 AttributeSetNode*> > Attrs);
224
225
226  explicit AttributeSet(AttributeSetImpl *LI) : pImpl(LI) {}
227public:
228  AttributeSet() : pImpl(0) {}
229
230  //===--------------------------------------------------------------------===//
231  // AttributeSet Construction and Mutation
232  //===--------------------------------------------------------------------===//
233
234  /// \brief Return an AttributeSet with the specified parameters in it.
235  static AttributeSet get(LLVMContext &C, ArrayRef<AttributeSet> Attrs);
236  static AttributeSet get(LLVMContext &C, unsigned Idx,
237                          ArrayRef<Attribute::AttrKind> Kind);
238  static AttributeSet get(LLVMContext &C, unsigned Idx, AttrBuilder &B);
239
240  /// \brief Add an attribute to the attribute set at the given index. Since
241  /// attribute sets are immutable, this returns a new set.
242  AttributeSet addAttribute(LLVMContext &C, unsigned Idx,
243                            Attribute::AttrKind Attr) const;
244
245  /// \brief Add an attribute to the attribute set at the given index. Since
246  /// attribute sets are immutable, this returns a new set.
247  AttributeSet addAttribute(LLVMContext &C, unsigned Idx,
248                            StringRef Kind) const;
249
250  /// \brief Add attributes to the attribute set at the given index. Since
251  /// attribute sets are immutable, this returns a new set.
252  AttributeSet addAttributes(LLVMContext &C, unsigned Idx,
253                             AttributeSet Attrs) const;
254
255  /// \brief Remove the specified attribute at the specified index from this
256  /// attribute list. Since attribute lists are immutable, this returns the new
257  /// list.
258  AttributeSet removeAttribute(LLVMContext &C, unsigned Idx,
259                               Attribute::AttrKind Attr) const;
260
261  /// \brief Remove the specified attributes at the specified index from this
262  /// attribute list. Since attribute lists are immutable, this returns the new
263  /// list.
264  AttributeSet removeAttributes(LLVMContext &C, unsigned Idx,
265                                AttributeSet Attrs) const;
266
267  //===--------------------------------------------------------------------===//
268  // AttributeSet Accessors
269  //===--------------------------------------------------------------------===//
270
271  /// \brief Retrieve the LLVM context.
272  LLVMContext &getContext() const;
273
274  /// \brief The attributes for the specified index are returned.
275  AttributeSet getParamAttributes(unsigned Idx) const;
276
277  /// \brief The attributes for the ret value are returned.
278  AttributeSet getRetAttributes() const;
279
280  /// \brief The function attributes are returned.
281  AttributeSet getFnAttributes() const;
282
283  /// \brief Return true if the attribute exists at the given index.
284  bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
285
286  /// \brief Return true if the attribute exists at the given index.
287  bool hasAttribute(unsigned Index, StringRef Kind) const;
288
289  /// \brief Return true if attribute exists at the given index.
290  bool hasAttributes(unsigned Index) const;
291
292  /// \brief Return true if the specified attribute is set for at least one
293  /// parameter or for the return value.
294  bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
295
296  /// \brief Return the attribute object that exists at the given index.
297  Attribute getAttribute(unsigned Index, Attribute::AttrKind Kind) const;
298
299  /// \brief Return the attribute object that exists at the given index.
300  Attribute getAttribute(unsigned Index, StringRef Kind) const;
301
302  /// \brief Return the alignment for the specified function parameter.
303  unsigned getParamAlignment(unsigned Idx) const;
304
305  /// \brief Get the stack alignment.
306  unsigned getStackAlignment(unsigned Index) const;
307
308  /// \brief Return the attributes at the index as a string.
309  std::string getAsString(unsigned Index, bool TargetIndependent = false,
310                          bool InAttrGrp = false) const;
311
312  typedef ArrayRef<Attribute>::iterator iterator;
313
314  iterator begin(unsigned Idx) const;
315  iterator end(unsigned Idx) const;
316
317  /// operator==/!= - Provide equality predicates.
318  bool operator==(const AttributeSet &RHS) const {
319    return pImpl == RHS.pImpl;
320  }
321  bool operator!=(const AttributeSet &RHS) const {
322    return pImpl != RHS.pImpl;
323  }
324
325  //===--------------------------------------------------------------------===//
326  // AttributeSet Introspection
327  //===--------------------------------------------------------------------===//
328
329  // FIXME: Remove this.
330  uint64_t Raw(unsigned Index) const;
331
332  /// \brief Return a raw pointer that uniquely identifies this attribute list.
333  void *getRawPointer() const {
334    return pImpl;
335  }
336
337  /// \brief Return true if there are no attributes.
338  bool isEmpty() const {
339    return getNumSlots() == 0;
340  }
341
342  /// \brief Return the number of slots used in this attribute list.  This is
343  /// the number of arguments that have an attribute set on them (including the
344  /// function itself).
345  unsigned getNumSlots() const;
346
347  /// \brief Return the index for the given slot.
348  uint64_t getSlotIndex(unsigned Slot) const;
349
350  /// \brief Return the attributes at the given slot.
351  AttributeSet getSlotAttributes(unsigned Slot) const;
352
353  void dump() const;
354};
355
356//===----------------------------------------------------------------------===//
357/// \class
358/// \brief Provide DenseMapInfo for AttributeSet.
359template<> struct DenseMapInfo<AttributeSet> {
360  static inline AttributeSet getEmptyKey() {
361    uintptr_t Val = static_cast<uintptr_t>(-1);
362    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
363    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
364  }
365  static inline AttributeSet getTombstoneKey() {
366    uintptr_t Val = static_cast<uintptr_t>(-2);
367    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
368    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
369  }
370  static unsigned getHashValue(AttributeSet AS) {
371    return (unsigned((uintptr_t)AS.pImpl) >> 4) ^
372           (unsigned((uintptr_t)AS.pImpl) >> 9);
373  }
374  static bool isEqual(AttributeSet LHS, AttributeSet RHS) { return LHS == RHS; }
375};
376
377//===----------------------------------------------------------------------===//
378/// \class
379/// \brief This class is used in conjunction with the Attribute::get method to
380/// create an Attribute object. The object itself is uniquified. The Builder's
381/// value, however, is not. So this can be used as a quick way to test for
382/// equality, presence of attributes, etc.
383class AttrBuilder {
384  std::bitset<Attribute::EndAttrKinds> Attrs;
385  std::map<std::string, std::string> TargetDepAttrs;
386  uint64_t Alignment;
387  uint64_t StackAlignment;
388public:
389  AttrBuilder() : Attrs(0), Alignment(0), StackAlignment(0) {}
390  explicit AttrBuilder(uint64_t Val)
391    : Attrs(0), Alignment(0), StackAlignment(0) {
392    addRawValue(Val);
393  }
394  AttrBuilder(const Attribute &A) : Attrs(0), Alignment(0), StackAlignment(0) {
395    addAttribute(A);
396  }
397  AttrBuilder(AttributeSet AS, unsigned Idx);
398  AttrBuilder(const AttrBuilder &B)
399    : Attrs(B.Attrs),
400      TargetDepAttrs(B.TargetDepAttrs.begin(), B.TargetDepAttrs.end()),
401      Alignment(B.Alignment), StackAlignment(B.StackAlignment) {}
402
403  void clear();
404
405  /// \brief Add an attribute to the builder.
406  AttrBuilder &addAttribute(Attribute::AttrKind Val);
407
408  /// \brief Add the Attribute object to the builder.
409  AttrBuilder &addAttribute(Attribute A);
410
411  /// \brief Add the target-dependent attribute to the builder.
412  AttrBuilder &addAttribute(StringRef A, StringRef V = StringRef());
413
414  /// \brief Remove an attribute from the builder.
415  AttrBuilder &removeAttribute(Attribute::AttrKind Val);
416
417  /// \brief Remove the attributes from the builder.
418  AttrBuilder &removeAttributes(AttributeSet A, uint64_t Index);
419
420  /// \brief Remove the target-dependent attribute to the builder.
421  AttrBuilder &removeAttribute(StringRef A);
422
423  /// \brief Add the attributes from the builder.
424  AttrBuilder &merge(const AttrBuilder &B);
425
426  /// \brief Return true if the builder has the specified attribute.
427  bool contains(Attribute::AttrKind A) const {
428    assert((unsigned)A < Attribute::EndAttrKinds && "Attribute out of range!");
429    return Attrs[A];
430  }
431
432  /// \brief Return true if the builder has the specified target-dependent
433  /// attribute.
434  bool contains(StringRef A) const;
435
436  /// \brief Return true if the builder has IR-level attributes.
437  bool hasAttributes() const;
438
439  /// \brief Return true if the builder has any attribute that's in the
440  /// specified attribute.
441  bool hasAttributes(AttributeSet A, uint64_t Index) const;
442
443  /// \brief Return true if the builder has an alignment attribute.
444  bool hasAlignmentAttr() const;
445
446  /// \brief Retrieve the alignment attribute, if it exists.
447  uint64_t getAlignment() const { return Alignment; }
448
449  /// \brief Retrieve the stack alignment attribute, if it exists.
450  uint64_t getStackAlignment() const { return StackAlignment; }
451
452  /// \brief This turns an int alignment (which must be a power of 2) into the
453  /// form used internally in Attribute.
454  AttrBuilder &addAlignmentAttr(unsigned Align);
455
456  /// \brief This turns an int stack alignment (which must be a power of 2) into
457  /// the form used internally in Attribute.
458  AttrBuilder &addStackAlignmentAttr(unsigned Align);
459
460  /// \brief Return true if the builder contains no target-independent
461  /// attributes.
462  bool empty() const { return Attrs.none(); }
463
464  // Iterators for target-dependent attributes.
465  typedef std::pair<std::string, std::string>                td_type;
466  typedef std::map<std::string, std::string>::iterator       td_iterator;
467  typedef std::map<std::string, std::string>::const_iterator td_const_iterator;
468
469  td_iterator td_begin()             { return TargetDepAttrs.begin(); }
470  td_iterator td_end()               { return TargetDepAttrs.end(); }
471
472  td_const_iterator td_begin() const { return TargetDepAttrs.begin(); }
473  td_const_iterator td_end() const   { return TargetDepAttrs.end(); }
474
475  bool td_empty() const              { return TargetDepAttrs.empty(); }
476
477  bool operator==(const AttrBuilder &B);
478  bool operator!=(const AttrBuilder &B) {
479    return !(*this == B);
480  }
481
482  // FIXME: Remove this in 4.0.
483
484  /// \brief Add the raw value to the internal representation.
485  AttrBuilder &addRawValue(uint64_t Val);
486};
487
488namespace AttributeFuncs {
489
490/// \brief Which attributes cannot be applied to a type.
491AttributeSet typeIncompatible(Type *Ty, uint64_t Index);
492
493} // end AttributeFuncs namespace
494
495} // end llvm namespace
496
497#endif
498