Attributes.h revision 87de71cb9f12d874e88d4f314ab245985c1b36bc 
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    UWTable,               ///< Function must be in a unwind table
99    ZExt,                  ///< Zero extended before/after call
100
101    EndAttrKinds,          ///< Sentinal value useful for loops
102
103    AttrKindEmptyKey,      ///< Empty key value for DenseMapInfo
104    AttrKindTombstoneKey   ///< Tombstone key value for DenseMapInfo
105  };
106private:
107  AttributeImpl *pImpl;
108  Attribute(AttributeImpl *A) : pImpl(A) {}
109public:
110  Attribute() : pImpl(0) {}
111
112  //===--------------------------------------------------------------------===//
113  // Attribute Construction
114  //===--------------------------------------------------------------------===//
115
116  /// \brief Return a uniquified Attribute object.
117  static Attribute get(LLVMContext &Context, AttrKind Kind, uint64_t Val = 0);
118  static Attribute get(LLVMContext &Context, StringRef Kind,
119                       StringRef Val = StringRef());
120
121  /// \brief Return a uniquified Attribute object that has the specific
122  /// alignment set.
123  static Attribute getWithAlignment(LLVMContext &Context, uint64_t Align);
124  static Attribute getWithStackAlignment(LLVMContext &Context, uint64_t Align);
125
126  //===--------------------------------------------------------------------===//
127  // Attribute Accessors
128  //===--------------------------------------------------------------------===//
129
130  /// \brief Return true if the attribute is an Attribute::AttrKind type.
131  bool isEnumAttribute() const;
132
133  /// \brief Return true if the attribute is an alignment attribute.
134  bool isAlignAttribute() const;
135
136  /// \brief Return true if the attribute is a string (target-dependent)
137  /// attribute.
138  bool isStringAttribute() const;
139
140  /// \brief Return true if the attribute is present.
141  bool hasAttribute(AttrKind Val) const;
142
143  /// \brief Return true if the target-dependent attribute is present.
144  bool hasAttribute(StringRef Val) const;
145
146  /// \brief Return the attribute's kind as an enum (Attribute::AttrKind). This
147  /// requires the attribute to be an enum or alignment attribute.
148  Attribute::AttrKind getKindAsEnum() const;
149
150  /// \brief Return the attribute's value as an integer. This requires that the
151  /// attribute be an alignment attribute.
152  uint64_t getValueAsInt() const;
153
154  /// \brief Return the attribute's kind as a string. This requires the
155  /// attribute to be a string attribute.
156  StringRef getKindAsString() const;
157
158  /// \brief Return the attribute's value as a string. This requires the
159  /// attribute to be a string attribute.
160  StringRef getValueAsString() const;
161
162  /// \brief Returns the alignment field of an attribute as a byte alignment
163  /// value.
164  unsigned getAlignment() const;
165
166  /// \brief Returns the stack alignment field of an attribute as a byte
167  /// alignment value.
168  unsigned getStackAlignment() const;
169
170  /// \brief The Attribute is converted to a string of equivalent mnemonic. This
171  /// is, presumably, for writing out the mnemonics for the assembly writer.
172  std::string getAsString() const;
173
174  /// \brief Equality and non-equality operators.
175  bool operator==(Attribute A) const { return pImpl == A.pImpl; }
176  bool operator!=(Attribute A) const { return pImpl != A.pImpl; }
177
178  /// \brief Less-than operator. Useful for sorting the attributes list.
179  bool operator<(Attribute A) const;
180
181  void Profile(FoldingSetNodeID &ID) const {
182    ID.AddPointer(pImpl);
183  }
184};
185
186//===----------------------------------------------------------------------===//
187/// \class
188/// \brief Provide DenseMapInfo for Attribute::AttrKinds. This is used by
189/// AttrBuilder.
190template<> struct DenseMapInfo<Attribute::AttrKind> {
191  static inline Attribute::AttrKind getEmptyKey() {
192    return Attribute::AttrKindEmptyKey;
193  }
194  static inline Attribute::AttrKind getTombstoneKey() {
195    return Attribute::AttrKindTombstoneKey;
196  }
197  static unsigned getHashValue(const Attribute::AttrKind &Val) {
198    return Val * 37U;
199  }
200  static bool isEqual(const Attribute::AttrKind &LHS,
201                      const Attribute::AttrKind &RHS) {
202    return LHS == RHS;
203  }
204};
205
206//===----------------------------------------------------------------------===//
207/// \class
208/// \brief This class holds the attributes for a function, its return value, and
209/// its parameters. You access the attributes for each of them via an index into
210/// the AttributeSet object. The function attributes are at index
211/// `AttributeSet::FunctionIndex', the return value is at index
212/// `AttributeSet::ReturnIndex', and the attributes for the parameters start at
213/// index `1'.
214class AttributeSet {
215public:
216  enum AttrIndex {
217    ReturnIndex = 0U,
218    FunctionIndex = ~0U
219  };
220private:
221  friend class AttrBuilder;
222  friend class AttributeSetImpl;
223  template <typename Ty> friend struct DenseMapInfo;
224
225  /// \brief The attributes that we are managing. This can be null to represent
226  /// the empty attributes list.
227  AttributeSetImpl *pImpl;
228
229  /// \brief The attributes for the specified index are returned.
230  AttributeSetNode *getAttributes(unsigned Idx) const;
231
232  /// \brief Create an AttributeSet with the specified parameters in it.
233  static AttributeSet get(LLVMContext &C,
234                          ArrayRef<std::pair<unsigned, Attribute> > Attrs);
235  static AttributeSet get(LLVMContext &C,
236                          ArrayRef<std::pair<unsigned,
237                                             AttributeSetNode*> > Attrs);
238
239  static AttributeSet getImpl(LLVMContext &C,
240                              ArrayRef<std::pair<unsigned,
241                                                 AttributeSetNode*> > Attrs);
242
243
244  explicit AttributeSet(AttributeSetImpl *LI) : pImpl(LI) {}
245public:
246  AttributeSet() : pImpl(0) {}
247  AttributeSet(const AttributeSet &P) : pImpl(P.pImpl) {}
248  const AttributeSet &operator=(const AttributeSet &RHS) {
249    pImpl = RHS.pImpl;
250    return *this;
251  }
252
253  //===--------------------------------------------------------------------===//
254  // AttributeSet Construction and Mutation
255  //===--------------------------------------------------------------------===//
256
257  /// \brief Return an AttributeSet with the specified parameters in it.
258  static AttributeSet get(LLVMContext &C, ArrayRef<AttributeSet> Attrs);
259  static AttributeSet get(LLVMContext &C, unsigned Idx,
260                          ArrayRef<Attribute::AttrKind> Kind);
261  static AttributeSet get(LLVMContext &C, unsigned Idx, AttrBuilder &B);
262
263  /// \brief Add an attribute to the attribute set at the given index. Since
264  /// attribute sets are immutable, this returns a new set.
265  AttributeSet addAttribute(LLVMContext &C, unsigned Idx,
266                            Attribute::AttrKind Attr) const;
267
268  /// \brief Add attributes to the attribute set at the given index. Since
269  /// attribute sets are immutable, this returns a new set.
270  AttributeSet addAttributes(LLVMContext &C, unsigned Idx,
271                             AttributeSet Attrs) const;
272
273  /// \brief Remove the specified attribute at the specified index from this
274  /// attribute list. Since attribute lists are immutable, this returns the new
275  /// list.
276  AttributeSet removeAttribute(LLVMContext &C, unsigned Idx,
277                               Attribute::AttrKind Attr) const;
278
279  /// \brief Remove the specified attributes at the specified index from this
280  /// attribute list. Since attribute lists are immutable, this returns the new
281  /// list.
282  AttributeSet removeAttributes(LLVMContext &C, unsigned Idx,
283                                AttributeSet Attrs) const;
284
285  //===--------------------------------------------------------------------===//
286  // AttributeSet Accessors
287  //===--------------------------------------------------------------------===//
288
289  /// \brief Retrieve the LLVM context.
290  LLVMContext &getContext() const;
291
292  /// \brief The attributes for the specified index are returned.
293  AttributeSet getParamAttributes(unsigned Idx) const;
294
295  /// \brief The attributes for the ret value are returned.
296  AttributeSet getRetAttributes() const;
297
298  /// \brief The function attributes are returned.
299  AttributeSet getFnAttributes() const;
300
301  /// \brief Return true if the attribute exists at the given index.
302  bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
303
304  /// \brief Return true if attribute exists at the given index.
305  bool hasAttributes(unsigned Index) const;
306
307  /// \brief Return true if the specified attribute is set for at least one
308  /// parameter or for the return value.
309  bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
310
311  /// \brief Return the alignment for the specified function parameter.
312  unsigned getParamAlignment(unsigned Idx) const;
313
314  /// \brief Get the stack alignment.
315  unsigned getStackAlignment(unsigned Index) const;
316
317  /// \brief Return the attributes at the index as a string.
318  std::string getAsString(unsigned Index) const;
319
320  typedef ArrayRef<Attribute>::iterator iterator;
321
322  iterator begin(unsigned Idx) const;
323  iterator end(unsigned Idx) const;
324
325  /// operator==/!= - Provide equality predicates.
326  bool operator==(const AttributeSet &RHS) const {
327    return pImpl == RHS.pImpl;
328  }
329  bool operator!=(const AttributeSet &RHS) const {
330    return pImpl != RHS.pImpl;
331  }
332
333  //===--------------------------------------------------------------------===//
334  // AttributeSet Introspection
335  //===--------------------------------------------------------------------===//
336
337  // FIXME: Remove this.
338  uint64_t Raw(unsigned Index) const;
339
340  /// \brief Return a raw pointer that uniquely identifies this attribute list.
341  void *getRawPointer() const {
342    return pImpl;
343  }
344
345  /// \brief Return true if there are no attributes.
346  bool isEmpty() const {
347    return getNumSlots() == 0;
348  }
349
350  /// \brief Return the number of slots used in this attribute list.  This is
351  /// the number of arguments that have an attribute set on them (including the
352  /// function itself).
353  unsigned getNumSlots() const;
354
355  /// \brief Return the index for the given slot.
356  uint64_t getSlotIndex(unsigned Slot) const;
357
358  /// \brief Return the attributes at the given slot.
359  AttributeSet getSlotAttributes(unsigned Slot) const;
360
361  void dump() const;
362};
363
364//===----------------------------------------------------------------------===//
365/// \class
366/// \brief Provide DenseMapInfo for AttributeSet.
367template<> struct DenseMapInfo<AttributeSet> {
368  static inline AttributeSet getEmptyKey() {
369    uintptr_t Val = static_cast<uintptr_t>(-1);
370    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
371    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
372  }
373  static inline AttributeSet getTombstoneKey() {
374    uintptr_t Val = static_cast<uintptr_t>(-2);
375    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
376    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
377  }
378  static unsigned getHashValue(AttributeSet AS) {
379    return (unsigned((uintptr_t)AS.pImpl) >> 4) ^
380           (unsigned((uintptr_t)AS.pImpl) >> 9);
381  }
382  static bool isEqual(AttributeSet LHS, AttributeSet RHS) { return LHS == RHS; }
383};
384
385//===----------------------------------------------------------------------===//
386/// \class
387/// \brief This class is used in conjunction with the Attribute::get method to
388/// create an Attribute object. The object itself is uniquified. The Builder's
389/// value, however, is not. So this can be used as a quick way to test for
390/// equality, presence of attributes, etc.
391class AttrBuilder {
392  DenseSet<Attribute::AttrKind> Attrs;
393  std::map<std::string, std::string> TargetDepAttrs;
394  uint64_t Alignment;
395  uint64_t StackAlignment;
396public:
397  AttrBuilder() : Alignment(0), StackAlignment(0) {}
398  explicit AttrBuilder(uint64_t Val) : Alignment(0), StackAlignment(0) {
399    addRawValue(Val);
400  }
401  AttrBuilder(const Attribute &A) : 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);
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
436  /// \brief Return true if the builder has the specified target-dependent
437  /// attribute.
438  bool contains(StringRef A) const;
439
440  /// \brief Return true if the builder has IR-level attributes.
441  bool hasAttributes() const;
442
443  /// \brief Return true if the builder has any attribute that's in the
444  /// specified attribute.
445  bool hasAttributes(AttributeSet A, uint64_t Index) const;
446
447  /// \brief Return true if the builder has an alignment attribute.
448  bool hasAlignmentAttr() const;
449
450  /// \brief Retrieve the alignment attribute, if it exists.
451  uint64_t getAlignment() const { return Alignment; }
452
453  /// \brief Retrieve the stack alignment attribute, if it exists.
454  uint64_t getStackAlignment() const { return StackAlignment; }
455
456  /// \brief This turns an int alignment (which must be a power of 2) into the
457  /// form used internally in Attribute.
458  AttrBuilder &addAlignmentAttr(unsigned Align);
459
460  /// \brief This turns an int stack alignment (which must be a power of 2) into
461  /// the form used internally in Attribute.
462  AttrBuilder &addStackAlignmentAttr(unsigned Align);
463
464  // Iterators for target-independent attributes.
465  typedef DenseSet<Attribute::AttrKind>::iterator       iterator;
466  typedef DenseSet<Attribute::AttrKind>::const_iterator const_iterator;
467
468  iterator begin()             { return Attrs.begin(); }
469  iterator end()               { return Attrs.end(); }
470
471  const_iterator begin() const { return Attrs.begin(); }
472  const_iterator end() const   { return Attrs.end(); }
473
474  bool empty() const           { return Attrs.empty(); }
475
476  // Iterators for target-dependent attributes.
477  typedef std::pair<std::string, std::string>                td_type;
478  typedef std::map<std::string, std::string>::iterator       td_iterator;
479  typedef std::map<std::string, std::string>::const_iterator td_const_iterator;
480
481  td_iterator td_begin()             { return TargetDepAttrs.begin(); }
482  td_iterator td_end()               { return TargetDepAttrs.end(); }
483
484  td_const_iterator td_begin() const { return TargetDepAttrs.begin(); }
485  td_const_iterator td_end() const   { return TargetDepAttrs.end(); }
486
487  bool td_empty() const              { return TargetDepAttrs.empty(); }
488
489  /// \brief Remove attributes that are used on functions only.
490  void removeFunctionOnlyAttrs() {
491    removeAttribute(Attribute::NoReturn)
492      .removeAttribute(Attribute::NoUnwind)
493      .removeAttribute(Attribute::ReadNone)
494      .removeAttribute(Attribute::ReadOnly)
495      .removeAttribute(Attribute::NoInline)
496      .removeAttribute(Attribute::AlwaysInline)
497      .removeAttribute(Attribute::OptimizeForSize)
498      .removeAttribute(Attribute::StackProtect)
499      .removeAttribute(Attribute::StackProtectReq)
500      .removeAttribute(Attribute::StackProtectStrong)
501      .removeAttribute(Attribute::NoRedZone)
502      .removeAttribute(Attribute::NoImplicitFloat)
503      .removeAttribute(Attribute::Naked)
504      .removeAttribute(Attribute::InlineHint)
505      .removeAttribute(Attribute::StackAlignment)
506      .removeAttribute(Attribute::UWTable)
507      .removeAttribute(Attribute::NonLazyBind)
508      .removeAttribute(Attribute::ReturnsTwice)
509      .removeAttribute(Attribute::AddressSafety)
510      .removeAttribute(Attribute::MinSize)
511      .removeAttribute(Attribute::NoDuplicate);
512  }
513
514  bool operator==(const AttrBuilder &B);
515  bool operator!=(const AttrBuilder &B) {
516    return !(*this == B);
517  }
518
519  // FIXME: Remove this in 4.0.
520
521  /// \brief Add the raw value to the internal representation.
522  AttrBuilder &addRawValue(uint64_t Val);
523};
524
525namespace AttributeFuncs {
526
527/// \brief Which attributes cannot be applied to a type.
528AttributeSet typeIncompatible(Type *Ty, uint64_t Index);
529
530} // end AttributeFuncs namespace
531
532} // end llvm namespace
533
534#endif
535