Attributes.h revision 2253a2f52f3c46ae75cd05f5885acb987bd1d6b6 
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    Builtin,               ///< Callee is recognized as a builtin, despite
71                           ///< nobuiltin attribute on its declaration.
72    ByVal,                 ///< Pass structure by value
73    Cold,                  ///< Marks function as being in a cold path.
74    InlineHint,            ///< Source said inlining was desirable
75    InReg,                 ///< Force argument to be passed in register
76    MinSize,               ///< Function must be optimized for size first
77    Naked,                 ///< Naked function
78    Nest,                  ///< Nested function static chain
79    NoAlias,               ///< Considered to not alias after call
80    NoBuiltin,             ///< Callee isn't recognized as a builtin
81    NoCapture,             ///< Function creates no aliases of pointer
82    NoDuplicate,           ///< Call cannot be duplicated
83    NoImplicitFloat,       ///< Disable implicit floating point insts
84    NoInline,              ///< inline=never
85    NonLazyBind,           ///< Function is called early and/or
86                           ///< often, so lazy binding isn't worthwhile
87    NoRedZone,             ///< Disable redzone
88    NoReturn,              ///< Mark the function as not returning
89    NoUnwind,              ///< Function doesn't unwind stack
90    OptimizeForSize,       ///< opt_size
91    ReadNone,              ///< Function does not access memory
92    ReadOnly,              ///< Function only reads from memory
93    Returned,              ///< Return value is always equal to this argument
94    ReturnsTwice,          ///< Function can return twice
95    SExt,                  ///< Sign extended before/after call
96    StackAlignment,        ///< Alignment of stack for function (3 bits)
97                           ///< stored as log2 of alignment with +1 bias 0
98                           ///< means unaligned (different from
99                           ///< alignstack=(1))
100    StackProtect,          ///< Stack protection.
101    StackProtectReq,       ///< Stack protection required.
102    StackProtectStrong,    ///< Strong Stack protection.
103    StructRet,             ///< Hidden pointer to structure to return
104    SanitizeAddress,       ///< AddressSanitizer is on.
105    SanitizeThread,        ///< ThreadSanitizer is on.
106    SanitizeMemory,        ///< MemorySanitizer is on.
107    UWTable,               ///< Function must be in a unwind table
108    ZExt,                  ///< Zero extended before/after call
109
110    EndAttrKinds           ///< Sentinal value useful for loops
111  };
112private:
113  AttributeImpl *pImpl;
114  Attribute(AttributeImpl *A) : pImpl(A) {}
115public:
116  Attribute() : pImpl(0) {}
117
118  //===--------------------------------------------------------------------===//
119  // Attribute Construction
120  //===--------------------------------------------------------------------===//
121
122  /// \brief Return a uniquified Attribute object.
123  static Attribute get(LLVMContext &Context, AttrKind Kind, uint64_t Val = 0);
124  static Attribute get(LLVMContext &Context, StringRef Kind,
125                       StringRef Val = StringRef());
126
127  /// \brief Return a uniquified Attribute object that has the specific
128  /// alignment set.
129  static Attribute getWithAlignment(LLVMContext &Context, uint64_t Align);
130  static Attribute getWithStackAlignment(LLVMContext &Context, uint64_t Align);
131
132  //===--------------------------------------------------------------------===//
133  // Attribute Accessors
134  //===--------------------------------------------------------------------===//
135
136  /// \brief Return true if the attribute is an Attribute::AttrKind type.
137  bool isEnumAttribute() const;
138
139  /// \brief Return true if the attribute is an alignment attribute.
140  bool isAlignAttribute() const;
141
142  /// \brief Return true if the attribute is a string (target-dependent)
143  /// attribute.
144  bool isStringAttribute() const;
145
146  /// \brief Return true if the attribute is present.
147  bool hasAttribute(AttrKind Val) const;
148
149  /// \brief Return true if the target-dependent attribute is present.
150  bool hasAttribute(StringRef Val) const;
151
152  /// \brief Return the attribute's kind as an enum (Attribute::AttrKind). This
153  /// requires the attribute to be an enum or alignment attribute.
154  Attribute::AttrKind getKindAsEnum() const;
155
156  /// \brief Return the attribute's value as an integer. This requires that the
157  /// attribute be an alignment attribute.
158  uint64_t getValueAsInt() const;
159
160  /// \brief Return the attribute's kind as a string. This requires the
161  /// attribute to be a string attribute.
162  StringRef getKindAsString() const;
163
164  /// \brief Return the attribute's value as a string. This requires the
165  /// attribute to be a string attribute.
166  StringRef getValueAsString() const;
167
168  /// \brief Returns the alignment field of an attribute as a byte alignment
169  /// value.
170  unsigned getAlignment() const;
171
172  /// \brief Returns the stack alignment field of an attribute as a byte
173  /// alignment value.
174  unsigned getStackAlignment() const;
175
176  /// \brief The Attribute is converted to a string of equivalent mnemonic. This
177  /// is, presumably, for writing out the mnemonics for the assembly writer.
178  std::string getAsString(bool InAttrGrp = false) const;
179
180  /// \brief Equality and non-equality operators.
181  bool operator==(Attribute A) const { return pImpl == A.pImpl; }
182  bool operator!=(Attribute A) const { return pImpl != A.pImpl; }
183
184  /// \brief Less-than operator. Useful for sorting the attributes list.
185  bool operator<(Attribute A) const;
186
187  void Profile(FoldingSetNodeID &ID) const {
188    ID.AddPointer(pImpl);
189  }
190};
191
192//===----------------------------------------------------------------------===//
193/// \class
194/// \brief This class holds the attributes for a function, its return value, and
195/// its parameters. You access the attributes for each of them via an index into
196/// the AttributeSet object. The function attributes are at index
197/// `AttributeSet::FunctionIndex', the return value is at index
198/// `AttributeSet::ReturnIndex', and the attributes for the parameters start at
199/// index `1'.
200class AttributeSet {
201public:
202  enum AttrIndex {
203    ReturnIndex = 0U,
204    FunctionIndex = ~0U
205  };
206private:
207  friend class AttrBuilder;
208  friend class AttributeSetImpl;
209  template <typename Ty> friend struct DenseMapInfo;
210
211  /// \brief The attributes that we are managing. This can be null to represent
212  /// the empty attributes list.
213  AttributeSetImpl *pImpl;
214
215  /// \brief The attributes for the specified index are returned.
216  AttributeSetNode *getAttributes(unsigned Index) const;
217
218  /// \brief Create an AttributeSet with the specified parameters in it.
219  static AttributeSet get(LLVMContext &C,
220                          ArrayRef<std::pair<unsigned, Attribute> > Attrs);
221  static AttributeSet get(LLVMContext &C,
222                          ArrayRef<std::pair<unsigned,
223                                             AttributeSetNode*> > Attrs);
224
225  static AttributeSet getImpl(LLVMContext &C,
226                              ArrayRef<std::pair<unsigned,
227                                                 AttributeSetNode*> > Attrs);
228
229
230  explicit AttributeSet(AttributeSetImpl *LI) : pImpl(LI) {}
231public:
232  AttributeSet() : pImpl(0) {}
233
234  //===--------------------------------------------------------------------===//
235  // AttributeSet Construction and Mutation
236  //===--------------------------------------------------------------------===//
237
238  /// \brief Return an AttributeSet with the specified parameters in it.
239  static AttributeSet get(LLVMContext &C, ArrayRef<AttributeSet> Attrs);
240  static AttributeSet get(LLVMContext &C, unsigned Index,
241                          ArrayRef<Attribute::AttrKind> Kind);
242  static AttributeSet get(LLVMContext &C, unsigned Index, AttrBuilder &B);
243
244  /// \brief Add an attribute to the attribute set at the given index. Since
245  /// attribute sets are immutable, this returns a new set.
246  AttributeSet addAttribute(LLVMContext &C, unsigned Index,
247                            Attribute::AttrKind Attr) const;
248
249  /// \brief Add an attribute to the attribute set at the given index. Since
250  /// attribute sets are immutable, this returns a new set.
251  AttributeSet addAttribute(LLVMContext &C, unsigned Index,
252                            StringRef Kind) const;
253
254  /// \brief Add attributes to the attribute set at the given index. Since
255  /// attribute sets are immutable, this returns a new set.
256  AttributeSet addAttributes(LLVMContext &C, unsigned Index,
257                             AttributeSet Attrs) const;
258
259  /// \brief Remove the specified attribute at the specified index from this
260  /// attribute list. Since attribute lists are immutable, this returns the new
261  /// list.
262  AttributeSet removeAttribute(LLVMContext &C, unsigned Index,
263                               Attribute::AttrKind Attr) const;
264
265  /// \brief Remove the specified attributes at the specified index from this
266  /// attribute list. Since attribute lists are immutable, this returns the new
267  /// list.
268  AttributeSet removeAttributes(LLVMContext &C, unsigned Index,
269                                AttributeSet Attrs) const;
270
271  //===--------------------------------------------------------------------===//
272  // AttributeSet Accessors
273  //===--------------------------------------------------------------------===//
274
275  /// \brief Retrieve the LLVM context.
276  LLVMContext &getContext() const;
277
278  /// \brief The attributes for the specified index are returned.
279  AttributeSet getParamAttributes(unsigned Index) const;
280
281  /// \brief The attributes for the ret value are returned.
282  AttributeSet getRetAttributes() const;
283
284  /// \brief The function attributes are returned.
285  AttributeSet getFnAttributes() const;
286
287  /// \brief Return true if the attribute exists at the given index.
288  bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
289
290  /// \brief Return true if the attribute exists at the given index.
291  bool hasAttribute(unsigned Index, StringRef Kind) const;
292
293  /// \brief Return true if attribute exists at the given index.
294  bool hasAttributes(unsigned Index) const;
295
296  /// \brief Return true if the specified attribute is set for at least one
297  /// parameter or for the return value.
298  bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
299
300  /// \brief Return the attribute object that exists at the given index.
301  Attribute getAttribute(unsigned Index, Attribute::AttrKind Kind) const;
302
303  /// \brief Return the attribute object that exists at the given index.
304  Attribute getAttribute(unsigned Index, StringRef Kind) const;
305
306  /// \brief Return the alignment for the specified function parameter.
307  unsigned getParamAlignment(unsigned Index) const;
308
309  /// \brief Get the stack alignment.
310  unsigned getStackAlignment(unsigned Index) const;
311
312  /// \brief Return the attributes at the index as a string.
313  std::string getAsString(unsigned Index, bool InAttrGrp = false) const;
314
315  typedef ArrayRef<Attribute>::iterator iterator;
316
317  iterator begin(unsigned Slot) const;
318  iterator end(unsigned Slot) const;
319
320  /// operator==/!= - Provide equality predicates.
321  bool operator==(const AttributeSet &RHS) const {
322    return pImpl == RHS.pImpl;
323  }
324  bool operator!=(const AttributeSet &RHS) const {
325    return pImpl != RHS.pImpl;
326  }
327
328  //===--------------------------------------------------------------------===//
329  // AttributeSet Introspection
330  //===--------------------------------------------------------------------===//
331
332  // FIXME: Remove this.
333  uint64_t Raw(unsigned Index) const;
334
335  /// \brief Return a raw pointer that uniquely identifies this attribute list.
336  void *getRawPointer() const {
337    return pImpl;
338  }
339
340  /// \brief Return true if there are no attributes.
341  bool isEmpty() const {
342    return getNumSlots() == 0;
343  }
344
345  /// \brief Return the number of slots used in this attribute list.  This is
346  /// the number of arguments that have an attribute set on them (including the
347  /// function itself).
348  unsigned getNumSlots() const;
349
350  /// \brief Return the index for the given slot.
351  unsigned getSlotIndex(unsigned Slot) const;
352
353  /// \brief Return the attributes at the given slot.
354  AttributeSet getSlotAttributes(unsigned Slot) const;
355
356  void dump() const;
357};
358
359//===----------------------------------------------------------------------===//
360/// \class
361/// \brief Provide DenseMapInfo for AttributeSet.
362template<> struct DenseMapInfo<AttributeSet> {
363  static inline AttributeSet getEmptyKey() {
364    uintptr_t Val = static_cast<uintptr_t>(-1);
365    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
366    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
367  }
368  static inline AttributeSet getTombstoneKey() {
369    uintptr_t Val = static_cast<uintptr_t>(-2);
370    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
371    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
372  }
373  static unsigned getHashValue(AttributeSet AS) {
374    return (unsigned((uintptr_t)AS.pImpl) >> 4) ^
375           (unsigned((uintptr_t)AS.pImpl) >> 9);
376  }
377  static bool isEqual(AttributeSet LHS, AttributeSet RHS) { return LHS == RHS; }
378};
379
380//===----------------------------------------------------------------------===//
381/// \class
382/// \brief This class is used in conjunction with the Attribute::get method to
383/// create an Attribute object. The object itself is uniquified. The Builder's
384/// value, however, is not. So this can be used as a quick way to test for
385/// equality, presence of attributes, etc.
386class AttrBuilder {
387  std::bitset<Attribute::EndAttrKinds> Attrs;
388  std::map<std::string, std::string> TargetDepAttrs;
389  uint64_t Alignment;
390  uint64_t StackAlignment;
391public:
392  AttrBuilder() : Attrs(0), Alignment(0), StackAlignment(0) {}
393  explicit AttrBuilder(uint64_t Val)
394    : Attrs(0), Alignment(0), StackAlignment(0) {
395    addRawValue(Val);
396  }
397  AttrBuilder(const Attribute &A) : Attrs(0), Alignment(0), StackAlignment(0) {
398    addAttribute(A);
399  }
400  AttrBuilder(AttributeSet AS, unsigned Idx);
401  AttrBuilder(const AttrBuilder &B)
402    : Attrs(B.Attrs),
403      TargetDepAttrs(B.TargetDepAttrs.begin(), B.TargetDepAttrs.end()),
404      Alignment(B.Alignment), StackAlignment(B.StackAlignment) {}
405
406  void clear();
407
408  /// \brief Add an attribute to the builder.
409  AttrBuilder &addAttribute(Attribute::AttrKind Val);
410
411  /// \brief Add the Attribute object to the builder.
412  AttrBuilder &addAttribute(Attribute A);
413
414  /// \brief Add the target-dependent attribute to the builder.
415  AttrBuilder &addAttribute(StringRef A, StringRef V = StringRef());
416
417  /// \brief Remove an attribute from the builder.
418  AttrBuilder &removeAttribute(Attribute::AttrKind Val);
419
420  /// \brief Remove the attributes from the builder.
421  AttrBuilder &removeAttributes(AttributeSet A, uint64_t Index);
422
423  /// \brief Remove the target-dependent attribute to the builder.
424  AttrBuilder &removeAttribute(StringRef A);
425
426  /// \brief Add the attributes from the builder.
427  AttrBuilder &merge(const AttrBuilder &B);
428
429  /// \brief Return true if the builder has the specified attribute.
430  bool contains(Attribute::AttrKind A) const {
431    assert((unsigned)A < Attribute::EndAttrKinds && "Attribute out of range!");
432    return Attrs[A];
433  }
434
435  /// \brief Return true if the builder has the specified target-dependent
436  /// attribute.
437  bool contains(StringRef A) const;
438
439  /// \brief Return true if the builder has IR-level attributes.
440  bool hasAttributes() const;
441
442  /// \brief Return true if the builder has any attribute that's in the
443  /// specified attribute.
444  bool hasAttributes(AttributeSet A, uint64_t Index) const;
445
446  /// \brief Return true if the builder has an alignment attribute.
447  bool hasAlignmentAttr() const;
448
449  /// \brief Retrieve the alignment attribute, if it exists.
450  uint64_t getAlignment() const { return Alignment; }
451
452  /// \brief Retrieve the stack alignment attribute, if it exists.
453  uint64_t getStackAlignment() const { return StackAlignment; }
454
455  /// \brief This turns an int alignment (which must be a power of 2) into the
456  /// form used internally in Attribute.
457  AttrBuilder &addAlignmentAttr(unsigned Align);
458
459  /// \brief This turns an int stack alignment (which must be a power of 2) into
460  /// the form used internally in Attribute.
461  AttrBuilder &addStackAlignmentAttr(unsigned Align);
462
463  /// \brief Return true if the builder contains no target-independent
464  /// attributes.
465  bool empty() const { return Attrs.none(); }
466
467  // Iterators for target-dependent attributes.
468  typedef std::pair<std::string, std::string>                td_type;
469  typedef std::map<std::string, std::string>::iterator       td_iterator;
470  typedef std::map<std::string, std::string>::const_iterator td_const_iterator;
471
472  td_iterator td_begin()             { return TargetDepAttrs.begin(); }
473  td_iterator td_end()               { return TargetDepAttrs.end(); }
474
475  td_const_iterator td_begin() const { return TargetDepAttrs.begin(); }
476  td_const_iterator td_end() const   { return TargetDepAttrs.end(); }
477
478  bool td_empty() const              { return TargetDepAttrs.empty(); }
479
480  bool operator==(const AttrBuilder &B);
481  bool operator!=(const AttrBuilder &B) {
482    return !(*this == B);
483  }
484
485  // FIXME: Remove this in 4.0.
486
487  /// \brief Add the raw value to the internal representation.
488  AttrBuilder &addRawValue(uint64_t Val);
489};
490
491namespace AttributeFuncs {
492
493/// \brief Which attributes cannot be applied to a type.
494AttributeSet typeIncompatible(Type *Ty, uint64_t Index);
495
496} // end AttributeFuncs namespace
497
498} // end llvm namespace
499
500#endif
501