Attributes.h revision 118a0659ab8a4d0e0af343b88e5fa71a5c1eb6a6 
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 LLVMContext;
37class Type;
38
39//===----------------------------------------------------------------------===//
40/// \class
41/// \brief Functions, function parameters, and return types can have attributes
42/// to indicate how they should be treated by optimizations and code
43/// generation. This class represents one of those attributes. It's light-weight
44/// and should be passed around by-value.
45class Attribute {
46public:
47  /// This enumeration lists the attributes that can be associated with
48  /// parameters, function results, or the function itself.
49  ///
50  /// Note: The `uwtable' attribute is about the ABI or the user mandating an
51  /// entry in the unwind table. The `nounwind' attribute is about an exception
52  /// passing by the function.
53  ///
54  /// In a theoretical system that uses tables for profiling and SjLj for
55  /// exceptions, they would be fully independent. In a normal system that uses
56  /// tables for both, the semantics are:
57  ///
58  /// nil                = Needs an entry because an exception might pass by.
59  /// nounwind           = No need for an entry
60  /// uwtable            = Needs an entry because the ABI says so and because
61  ///                      an exception might pass by.
62  /// uwtable + nounwind = Needs an entry because the ABI says so.
63
64  enum AttrKind {
65    // IR-Level Attributes
66    None,                  ///< No attributes have been set
67    Alignment,             ///< Alignment of parameter (5 bits)
68                           ///< stored as log2 of alignment with +1 bias
69                           ///< 0 means unaligned (different from align(1))
70    AlwaysInline,          ///< inline=always
71    Builtin,               ///< Callee is recognized as a builtin, despite
72                           ///< nobuiltin attribute on its declaration.
73    ByVal,                 ///< Pass structure by value
74    Cold,                  ///< Marks function as being in a cold path.
75    InlineHint,            ///< Source said inlining was desirable
76    InReg,                 ///< Force argument to be passed in register
77    MinSize,               ///< Function must be optimized for size first
78    Naked,                 ///< Naked function
79    Nest,                  ///< Nested function static chain
80    NoAlias,               ///< Considered to not alias after call
81    NoBuiltin,             ///< Callee isn't recognized as a builtin
82    NoCapture,             ///< Function creates no aliases of pointer
83    NoDuplicate,           ///< Call cannot be duplicated
84    NoImplicitFloat,       ///< Disable implicit floating point insts
85    NoInline,              ///< inline=never
86    NonLazyBind,           ///< Function is called early and/or
87                           ///< often, so lazy binding isn't worthwhile
88    NoRedZone,             ///< Disable redzone
89    NoReturn,              ///< Mark the function as not returning
90    NoUnwind,              ///< Function doesn't unwind stack
91    OptimizeForSize,       ///< opt_size
92    OptimizeNone,          ///< Function must not be optimized.
93    ReadNone,              ///< Function does not access memory
94    ReadOnly,              ///< Function only reads from memory
95    Returned,              ///< Return value is always equal to this argument
96    ReturnsTwice,          ///< Function can return twice
97    SExt,                  ///< Sign extended before/after call
98    StackAlignment,        ///< Alignment of stack for function (3 bits)
99                           ///< stored as log2 of alignment with +1 bias 0
100                           ///< means unaligned (different from
101                           ///< alignstack=(1))
102    StackProtect,          ///< Stack protection.
103    StackProtectReq,       ///< Stack protection required.
104    StackProtectStrong,    ///< Strong Stack protection.
105    StructRet,             ///< Hidden pointer to structure to return
106    SanitizeAddress,       ///< AddressSanitizer is on.
107    SanitizeThread,        ///< ThreadSanitizer is on.
108    SanitizeMemory,        ///< MemorySanitizer is on.
109    UWTable,               ///< Function must be in a unwind table
110    ZExt,                  ///< Zero extended before/after call
111
112    EndAttrKinds           ///< Sentinal value useful for loops
113  };
114private:
115  AttributeImpl *pImpl;
116  Attribute(AttributeImpl *A) : pImpl(A) {}
117public:
118  Attribute() : pImpl(0) {}
119
120  //===--------------------------------------------------------------------===//
121  // Attribute Construction
122  //===--------------------------------------------------------------------===//
123
124  /// \brief Return a uniquified Attribute object.
125  static Attribute get(LLVMContext &Context, AttrKind Kind, uint64_t Val = 0);
126  static Attribute get(LLVMContext &Context, StringRef Kind,
127                       StringRef Val = StringRef());
128
129  /// \brief Return a uniquified Attribute object that has the specific
130  /// alignment set.
131  static Attribute getWithAlignment(LLVMContext &Context, uint64_t Align);
132  static Attribute getWithStackAlignment(LLVMContext &Context, uint64_t Align);
133
134  //===--------------------------------------------------------------------===//
135  // Attribute Accessors
136  //===--------------------------------------------------------------------===//
137
138  /// \brief Return true if the attribute is an Attribute::AttrKind type.
139  bool isEnumAttribute() const;
140
141  /// \brief Return true if the attribute is an alignment attribute.
142  bool isAlignAttribute() const;
143
144  /// \brief Return true if the attribute is a string (target-dependent)
145  /// attribute.
146  bool isStringAttribute() const;
147
148  /// \brief Return true if the attribute is present.
149  bool hasAttribute(AttrKind Val) const;
150
151  /// \brief Return true if the target-dependent attribute is present.
152  bool hasAttribute(StringRef Val) const;
153
154  /// \brief Return the attribute's kind as an enum (Attribute::AttrKind). This
155  /// requires the attribute to be an enum or alignment attribute.
156  Attribute::AttrKind getKindAsEnum() const;
157
158  /// \brief Return the attribute's value as an integer. This requires that the
159  /// attribute be an alignment attribute.
160  uint64_t getValueAsInt() const;
161
162  /// \brief Return the attribute's kind as a string. This requires the
163  /// attribute to be a string attribute.
164  StringRef getKindAsString() const;
165
166  /// \brief Return the attribute's value as a string. This requires the
167  /// attribute to be a string attribute.
168  StringRef getValueAsString() const;
169
170  /// \brief Returns the alignment field of an attribute as a byte alignment
171  /// value.
172  unsigned getAlignment() const;
173
174  /// \brief Returns the stack alignment field of an attribute as a byte
175  /// alignment value.
176  unsigned getStackAlignment() const;
177
178  /// \brief The Attribute is converted to a string of equivalent mnemonic. This
179  /// is, presumably, for writing out the mnemonics for the assembly writer.
180  std::string getAsString(bool InAttrGrp = false) const;
181
182  /// \brief Equality and non-equality operators.
183  bool operator==(Attribute A) const { return pImpl == A.pImpl; }
184  bool operator!=(Attribute A) const { return pImpl != A.pImpl; }
185
186  /// \brief Less-than operator. Useful for sorting the attributes list.
187  bool operator<(Attribute A) const;
188
189  void Profile(FoldingSetNodeID &ID) const {
190    ID.AddPointer(pImpl);
191  }
192};
193
194//===----------------------------------------------------------------------===//
195/// \class
196/// \brief This class holds the attributes for a function, its return value, and
197/// its parameters. You access the attributes for each of them via an index into
198/// the AttributeSet object. The function attributes are at index
199/// `AttributeSet::FunctionIndex', the return value is at index
200/// `AttributeSet::ReturnIndex', and the attributes for the parameters start at
201/// index `1'.
202class AttributeSet {
203public:
204  enum AttrIndex LLVM_ENUM_INT_TYPE(unsigned) {
205    ReturnIndex = 0U,
206    FunctionIndex = ~0U
207  };
208private:
209  friend class AttrBuilder;
210  friend class AttributeSetImpl;
211  template <typename Ty> friend struct DenseMapInfo;
212
213  /// \brief The attributes that we are managing. This can be null to represent
214  /// the empty attributes list.
215  AttributeSetImpl *pImpl;
216
217  /// \brief The attributes for the specified index are returned.
218  AttributeSetNode *getAttributes(unsigned Index) const;
219
220  /// \brief Create an AttributeSet with the specified parameters in it.
221  static AttributeSet get(LLVMContext &C,
222                          ArrayRef<std::pair<unsigned, Attribute> > Attrs);
223  static AttributeSet get(LLVMContext &C,
224                          ArrayRef<std::pair<unsigned,
225                                             AttributeSetNode*> > Attrs);
226
227  static AttributeSet getImpl(LLVMContext &C,
228                              ArrayRef<std::pair<unsigned,
229                                                 AttributeSetNode*> > Attrs);
230
231
232  explicit AttributeSet(AttributeSetImpl *LI) : pImpl(LI) {}
233public:
234  AttributeSet() : pImpl(0) {}
235
236  //===--------------------------------------------------------------------===//
237  // AttributeSet Construction and Mutation
238  //===--------------------------------------------------------------------===//
239
240  /// \brief Return an AttributeSet with the specified parameters in it.
241  static AttributeSet get(LLVMContext &C, ArrayRef<AttributeSet> Attrs);
242  static AttributeSet get(LLVMContext &C, unsigned Index,
243                          ArrayRef<Attribute::AttrKind> Kind);
244  static AttributeSet get(LLVMContext &C, unsigned Index, AttrBuilder &B);
245
246  /// \brief Add an attribute to the attribute set at the given index. Since
247  /// attribute sets are immutable, this returns a new set.
248  AttributeSet addAttribute(LLVMContext &C, unsigned Index,
249                            Attribute::AttrKind Attr) const;
250
251  /// \brief Add an attribute to the attribute set at the given index. Since
252  /// attribute sets are immutable, this returns a new set.
253  AttributeSet addAttribute(LLVMContext &C, unsigned Index,
254                            StringRef Kind) const;
255  AttributeSet addAttribute(LLVMContext &C, unsigned Index,
256                            StringRef Kind, StringRef Value) const;
257
258  /// \brief Add attributes to the attribute set at the given index. Since
259  /// attribute sets are immutable, this returns a new set.
260  AttributeSet addAttributes(LLVMContext &C, unsigned Index,
261                             AttributeSet Attrs) const;
262
263  /// \brief Remove the specified attribute at the specified index from this
264  /// attribute list. Since attribute lists are immutable, this returns the new
265  /// list.
266  AttributeSet removeAttribute(LLVMContext &C, unsigned Index,
267                               Attribute::AttrKind Attr) const;
268
269  /// \brief Remove the specified attributes at the specified index from this
270  /// attribute list. Since attribute lists are immutable, this returns the new
271  /// list.
272  AttributeSet removeAttributes(LLVMContext &C, unsigned Index,
273                                AttributeSet Attrs) const;
274
275  //===--------------------------------------------------------------------===//
276  // AttributeSet Accessors
277  //===--------------------------------------------------------------------===//
278
279  /// \brief Retrieve the LLVM context.
280  LLVMContext &getContext() const;
281
282  /// \brief The attributes for the specified index are returned.
283  AttributeSet getParamAttributes(unsigned Index) const;
284
285  /// \brief The attributes for the ret value are returned.
286  AttributeSet getRetAttributes() const;
287
288  /// \brief The function attributes are returned.
289  AttributeSet getFnAttributes() const;
290
291  /// \brief Return true if the attribute exists at the given index.
292  bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
293
294  /// \brief Return true if the attribute exists at the given index.
295  bool hasAttribute(unsigned Index, StringRef Kind) const;
296
297  /// \brief Return true if attribute exists at the given index.
298  bool hasAttributes(unsigned Index) const;
299
300  /// \brief Return true if the specified attribute is set for at least one
301  /// parameter or for the return value.
302  bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
303
304  /// \brief Return the attribute object that exists at the given index.
305  Attribute getAttribute(unsigned Index, Attribute::AttrKind Kind) const;
306
307  /// \brief Return the attribute object that exists at the given index.
308  Attribute getAttribute(unsigned Index, StringRef Kind) const;
309
310  /// \brief Return the alignment for the specified function parameter.
311  unsigned getParamAlignment(unsigned Index) const;
312
313  /// \brief Get the stack alignment.
314  unsigned getStackAlignment(unsigned Index) const;
315
316  /// \brief Return the attributes at the index as a string.
317  std::string getAsString(unsigned Index, bool InAttrGrp = false) const;
318
319  typedef ArrayRef<Attribute>::iterator iterator;
320
321  iterator begin(unsigned Slot) const;
322  iterator end(unsigned Slot) const;
323
324  /// operator==/!= - Provide equality predicates.
325  bool operator==(const AttributeSet &RHS) const {
326    return pImpl == RHS.pImpl;
327  }
328  bool operator!=(const AttributeSet &RHS) const {
329    return pImpl != RHS.pImpl;
330  }
331
332  //===--------------------------------------------------------------------===//
333  // AttributeSet Introspection
334  //===--------------------------------------------------------------------===//
335
336  // FIXME: Remove this.
337  uint64_t Raw(unsigned Index) const;
338
339  /// \brief Return a raw pointer that uniquely identifies this attribute list.
340  void *getRawPointer() const {
341    return pImpl;
342  }
343
344  /// \brief Return true if there are no attributes.
345  bool isEmpty() const {
346    return getNumSlots() == 0;
347  }
348
349  /// \brief Return the number of slots used in this attribute list.  This is
350  /// the number of arguments that have an attribute set on them (including the
351  /// function itself).
352  unsigned getNumSlots() const;
353
354  /// \brief Return the index for the given slot.
355  unsigned getSlotIndex(unsigned Slot) const;
356
357  /// \brief Return the attributes at the given slot.
358  AttributeSet getSlotAttributes(unsigned Slot) const;
359
360  void dump() const;
361};
362
363//===----------------------------------------------------------------------===//
364/// \class
365/// \brief Provide DenseMapInfo for AttributeSet.
366template<> struct DenseMapInfo<AttributeSet> {
367  static inline AttributeSet getEmptyKey() {
368    uintptr_t Val = static_cast<uintptr_t>(-1);
369    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
370    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
371  }
372  static inline AttributeSet getTombstoneKey() {
373    uintptr_t Val = static_cast<uintptr_t>(-2);
374    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
375    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
376  }
377  static unsigned getHashValue(AttributeSet AS) {
378    return (unsigned((uintptr_t)AS.pImpl) >> 4) ^
379           (unsigned((uintptr_t)AS.pImpl) >> 9);
380  }
381  static bool isEqual(AttributeSet LHS, AttributeSet RHS) { return LHS == RHS; }
382};
383
384//===----------------------------------------------------------------------===//
385/// \class
386/// \brief This class is used in conjunction with the Attribute::get method to
387/// create an Attribute object. The object itself is uniquified. The Builder's
388/// value, however, is not. So this can be used as a quick way to test for
389/// equality, presence of attributes, etc.
390class AttrBuilder {
391  std::bitset<Attribute::EndAttrKinds> Attrs;
392  std::map<std::string, std::string> TargetDepAttrs;
393  uint64_t Alignment;
394  uint64_t StackAlignment;
395public:
396  AttrBuilder() : Attrs(0), Alignment(0), StackAlignment(0) {}
397  explicit AttrBuilder(uint64_t Val)
398    : Attrs(0), Alignment(0), StackAlignment(0) {
399    addRawValue(Val);
400  }
401  AttrBuilder(const Attribute &A) : Attrs(0), Alignment(0), StackAlignment(0) {
402    addAttribute(A);
403  }
404  AttrBuilder(AttributeSet AS, unsigned Idx);
405  AttrBuilder(const AttrBuilder &B)
406    : Attrs(B.Attrs),
407      TargetDepAttrs(B.TargetDepAttrs.begin(), B.TargetDepAttrs.end()),
408      Alignment(B.Alignment), StackAlignment(B.StackAlignment) {}
409
410  void clear();
411
412  /// \brief Add an attribute to the builder.
413  AttrBuilder &addAttribute(Attribute::AttrKind Val);
414
415  /// \brief Add the Attribute object to the builder.
416  AttrBuilder &addAttribute(Attribute A);
417
418  /// \brief Add the target-dependent attribute to the builder.
419  AttrBuilder &addAttribute(StringRef A, StringRef V = StringRef());
420
421  /// \brief Remove an attribute from the builder.
422  AttrBuilder &removeAttribute(Attribute::AttrKind Val);
423
424  /// \brief Remove the attributes from the builder.
425  AttrBuilder &removeAttributes(AttributeSet A, uint64_t Index);
426
427  /// \brief Remove the target-dependent attribute to the builder.
428  AttrBuilder &removeAttribute(StringRef A);
429
430  /// \brief Add the attributes from the builder.
431  AttrBuilder &merge(const AttrBuilder &B);
432
433  /// \brief Return true if the builder has the specified attribute.
434  bool contains(Attribute::AttrKind A) const {
435    assert((unsigned)A < Attribute::EndAttrKinds && "Attribute out of range!");
436    return Attrs[A];
437  }
438
439  /// \brief Return true if the builder has the specified target-dependent
440  /// attribute.
441  bool contains(StringRef A) const;
442
443  /// \brief Return true if the builder has IR-level attributes.
444  bool hasAttributes() const;
445
446  /// \brief Return true if the builder has any attribute that's in the
447  /// specified attribute.
448  bool hasAttributes(AttributeSet A, uint64_t Index) const;
449
450  /// \brief Return true if the builder has an alignment attribute.
451  bool hasAlignmentAttr() const;
452
453  /// \brief Retrieve the alignment attribute, if it exists.
454  uint64_t getAlignment() const { return Alignment; }
455
456  /// \brief Retrieve the stack alignment attribute, if it exists.
457  uint64_t getStackAlignment() const { return StackAlignment; }
458
459  /// \brief This turns an int alignment (which must be a power of 2) into the
460  /// form used internally in Attribute.
461  AttrBuilder &addAlignmentAttr(unsigned Align);
462
463  /// \brief This turns an int stack alignment (which must be a power of 2) into
464  /// the form used internally in Attribute.
465  AttrBuilder &addStackAlignmentAttr(unsigned Align);
466
467  /// \brief Return true if the builder contains no target-independent
468  /// attributes.
469  bool empty() const { return Attrs.none(); }
470
471  // Iterators for target-dependent attributes.
472  typedef std::pair<std::string, std::string>                td_type;
473  typedef std::map<std::string, std::string>::iterator       td_iterator;
474  typedef std::map<std::string, std::string>::const_iterator td_const_iterator;
475
476  td_iterator td_begin()             { return TargetDepAttrs.begin(); }
477  td_iterator td_end()               { return TargetDepAttrs.end(); }
478
479  td_const_iterator td_begin() const { return TargetDepAttrs.begin(); }
480  td_const_iterator td_end() const   { return TargetDepAttrs.end(); }
481
482  bool td_empty() const              { return TargetDepAttrs.empty(); }
483
484  bool operator==(const AttrBuilder &B);
485  bool operator!=(const AttrBuilder &B) {
486    return !(*this == B);
487  }
488
489  // FIXME: Remove this in 4.0.
490
491  /// \brief Add the raw value to the internal representation.
492  AttrBuilder &addRawValue(uint64_t Val);
493};
494
495namespace AttributeFuncs {
496
497/// \brief Which attributes cannot be applied to a type.
498AttributeSet typeIncompatible(Type *Ty, uint64_t Index);
499
500} // end AttributeFuncs namespace
501
502} // end llvm namespace
503
504#endif
505