Attributes.h revision f715dbd263149efeb9c684dfdb0637cf84f94399 
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 <string>
24
25namespace llvm {
26
27class AttrBuilder;
28class AttributeImpl;
29class AttributeSetImpl;
30class AttributeSetNode;
31class Constant;
32class LLVMContext;
33class Type;
34
35//===----------------------------------------------------------------------===//
36/// \class
37/// \brief Functions, function parameters, and return types can have attributes
38/// to indicate how they should be treated by optimizations and code
39/// generation. This class represents one of those attributes. It's light-weight
40/// and should be passed around by-value.
41class Attribute {
42public:
43  /// This enumeration lists the attributes that can be associated with
44  /// parameters, function results, or the function itself.
45  ///
46  /// Note: The `uwtable' attribute is about the ABI or the user mandating an
47  /// entry in the unwind table. The `nounwind' attribute is about an exception
48  /// passing by the function.
49  ///
50  /// In a theoretical system that uses tables for profiling and SjLj for
51  /// exceptions, they would be fully independent. In a normal system that uses
52  /// tables for both, the semantics are:
53  ///
54  /// nil                = Needs an entry because an exception might pass by.
55  /// nounwind           = No need for an entry
56  /// uwtable            = Needs an entry because the ABI says so and because
57  ///                      an exception might pass by.
58  /// uwtable + nounwind = Needs an entry because the ABI says so.
59
60  enum AttrKind {
61    // IR-Level Attributes
62    None,                  ///< No attributes have been set
63    AddressSafety,         ///< Address safety checking is on.
64    Alignment,             ///< Alignment of parameter (5 bits)
65                           ///< stored as log2 of alignment with +1 bias
66                           ///< 0 means unaligned (different from align(1))
67    AlwaysInline,          ///< inline=always
68    ByVal,                 ///< Pass structure by value
69    InlineHint,            ///< Source said inlining was desirable
70    InReg,                 ///< Force argument to be passed in register
71    MinSize,               ///< Function must be optimized for size first
72    Naked,                 ///< Naked function
73    Nest,                  ///< Nested function static chain
74    NoAlias,               ///< Considered to not alias after call
75    NoCapture,             ///< Function creates no aliases of pointer
76    NoDuplicate,           ///< Call cannot be duplicated
77    NoImplicitFloat,       ///< Disable implicit floating point insts
78    NoInline,              ///< inline=never
79    NonLazyBind,           ///< Function is called early and/or
80                           ///< often, so lazy binding isn't worthwhile
81    NoRedZone,             ///< Disable redzone
82    NoReturn,              ///< Mark the function as not returning
83    NoUnwind,              ///< Function doesn't unwind stack
84    OptimizeForSize,       ///< opt_size
85    ReadNone,              ///< Function does not access memory
86    ReadOnly,              ///< Function only reads from memory
87    ReturnsTwice,          ///< Function can return twice
88    SExt,                  ///< Sign extended before/after call
89    StackAlignment,        ///< Alignment of stack for function (3 bits)
90                           ///< stored as log2 of alignment with +1 bias 0
91                           ///< means unaligned (different from
92                           ///< alignstack=(1))
93    StackProtect,          ///< Stack protection.
94    StackProtectReq,       ///< Stack protection required.
95    StackProtectStrong,    ///< Strong Stack protection.
96    StructRet,             ///< Hidden pointer to structure to return
97    UWTable,               ///< Function must be in a unwind table
98    ZExt,                  ///< Zero extended before/after call
99
100    EndAttrKinds,          ///< Sentinal value useful for loops
101
102    AttrKindEmptyKey,      ///< Empty key value for DenseMapInfo
103    AttrKindTombstoneKey   ///< Tombstone key value for DenseMapInfo
104  };
105private:
106  AttributeImpl *pImpl;
107  Attribute(AttributeImpl *A) : pImpl(A) {}
108public:
109  Attribute() : pImpl(0) {}
110
111  //===--------------------------------------------------------------------===//
112  // Attribute Construction
113  //===--------------------------------------------------------------------===//
114
115  /// \brief Return a uniquified Attribute object.
116  static Attribute get(LLVMContext &Context, AttrKind Kind, Constant *Val = 0);
117  static Attribute get(LLVMContext &Context, Constant *Kind, Constant *Val = 0);
118
119  /// \brief Return a uniquified Attribute object that has the specific
120  /// alignment set.
121  static Attribute getWithAlignment(LLVMContext &Context, uint64_t Align);
122  static Attribute getWithStackAlignment(LLVMContext &Context, uint64_t Align);
123
124  //===--------------------------------------------------------------------===//
125  // Attribute Accessors
126  //===--------------------------------------------------------------------===//
127
128  /// \brief Return true if the attribute is present.
129  bool hasAttribute(AttrKind Val) const;
130
131  /// \brief Return the kind of this attribute.
132  Constant *getAttributeKind() const;
133
134  /// \brief Return the value (if present) of the non-target-specific attribute.
135  ArrayRef<Constant*> getAttributeValues() const;
136
137  /// \brief Returns the alignment field of an attribute as a byte alignment
138  /// value.
139  unsigned getAlignment() const;
140
141  /// \brief Returns the stack alignment field of an attribute as a byte
142  /// alignment value.
143  unsigned getStackAlignment() const;
144
145  /// \brief The Attribute is converted to a string of equivalent mnemonic. This
146  /// is, presumably, for writing out the mnemonics for the assembly writer.
147  std::string getAsString() const;
148
149  /// \brief Equality and non-equality query methods.
150  bool operator==(AttrKind K) const;
151  bool operator!=(AttrKind K) const;
152
153  bool operator==(Attribute A) const { return pImpl == A.pImpl; }
154  bool operator!=(Attribute A) const { return pImpl != A.pImpl; }
155
156  /// \brief Less-than operator. Useful for sorting the attributes list.
157  bool operator<(Attribute A) const;
158
159  void Profile(FoldingSetNodeID &ID) const {
160    ID.AddPointer(pImpl);
161  }
162};
163
164//===----------------------------------------------------------------------===//
165/// \class
166/// \brief This class manages the ref count for the opaque AttributeSetImpl
167/// object and provides accessors for it.
168class AttributeSet {
169public:
170  enum AttrIndex {
171    ReturnIndex = 0U,
172    FunctionIndex = ~0U
173  };
174private:
175  friend class AttrBuilder;
176  friend class AttributeSetImpl;
177
178  /// \brief The attributes that we are managing. This can be null to represent
179  /// the empty attributes list.
180  AttributeSetImpl *pImpl;
181
182  /// \brief The attributes for the specified index are returned.
183  AttributeSetNode *getAttributes(unsigned Idx) const;
184
185  /// \brief Create an AttributeSet with the specified parameters in it.
186  static AttributeSet get(LLVMContext &C,
187                          ArrayRef<std::pair<unsigned, Attribute> > Attrs);
188  static AttributeSet get(LLVMContext &C,
189                          ArrayRef<std::pair<unsigned,
190                                             AttributeSetNode*> > Attrs);
191
192  static AttributeSet getImpl(LLVMContext &C,
193                              ArrayRef<std::pair<unsigned,
194                                                 AttributeSetNode*> > Attrs);
195
196
197  explicit AttributeSet(AttributeSetImpl *LI) : pImpl(LI) {}
198public:
199  AttributeSet() : pImpl(0) {}
200  AttributeSet(const AttributeSet &P) : pImpl(P.pImpl) {}
201  const AttributeSet &operator=(const AttributeSet &RHS) {
202    pImpl = RHS.pImpl;
203    return *this;
204  }
205
206  //===--------------------------------------------------------------------===//
207  // AttributeSet Construction and Mutation
208  //===--------------------------------------------------------------------===//
209
210  /// \brief Return an AttributeSet with the specified parameters in it.
211  static AttributeSet get(LLVMContext &C, ArrayRef<AttributeSet> Attrs);
212  static AttributeSet get(LLVMContext &C, unsigned Idx,
213                          ArrayRef<Attribute::AttrKind> Kind);
214  static AttributeSet get(LLVMContext &C, unsigned Idx, AttrBuilder &B);
215
216  /// \brief Add an attribute to the attribute set at the given index. Since
217  /// attribute sets are immutable, this returns a new set.
218  AttributeSet addAttribute(LLVMContext &C, unsigned Idx,
219                            Attribute::AttrKind Attr) const;
220
221  /// \brief Add attributes to the attribute set at the given index. Since
222  /// attribute sets are immutable, this returns a new set.
223  AttributeSet addAttributes(LLVMContext &C, unsigned Idx,
224                             AttributeSet Attrs) const;
225
226  /// \brief Remove the specified attribute at the specified index from this
227  /// attribute list. Since attribute lists are immutable, this returns the new
228  /// list.
229  AttributeSet removeAttribute(LLVMContext &C, unsigned Idx,
230                               Attribute::AttrKind Attr) const;
231
232  /// \brief Remove the specified attributes at the specified index from this
233  /// attribute list. Since attribute lists are immutable, this returns the new
234  /// list.
235  AttributeSet removeAttributes(LLVMContext &C, unsigned Idx,
236                                AttributeSet Attrs) const;
237
238  //===--------------------------------------------------------------------===//
239  // AttributeSet Accessors
240  //===--------------------------------------------------------------------===//
241
242  /// \brief The attributes for the specified index are returned.
243  AttributeSet getParamAttributes(unsigned Idx) const;
244
245  /// \brief The attributes for the ret value are returned.
246  AttributeSet getRetAttributes() const;
247
248  /// \brief The function attributes are returned.
249  AttributeSet getFnAttributes() const;
250
251  /// \brief Return true if the attribute exists at the given index.
252  bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
253
254  /// \brief Return true if attribute exists at the given index.
255  bool hasAttributes(unsigned Index) const;
256
257  /// \brief Return true if the specified attribute is set for at least one
258  /// parameter or for the return value.
259  bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
260
261  /// \brief Return the alignment for the specified function parameter.
262  unsigned getParamAlignment(unsigned Idx) const;
263
264  /// \brief Get the stack alignment.
265  unsigned getStackAlignment(unsigned Index) const;
266
267  /// \brief Return the attributes at the index as a string.
268  std::string getAsString(unsigned Index) const;
269
270  typedef ArrayRef<Attribute>::iterator iterator;
271
272  iterator begin(unsigned Idx) const;
273  iterator end(unsigned Idx) const;
274
275  /// operator==/!= - Provide equality predicates.
276  bool operator==(const AttributeSet &RHS) const {
277    return pImpl == RHS.pImpl;
278  }
279  bool operator!=(const AttributeSet &RHS) const {
280    return pImpl != RHS.pImpl;
281  }
282
283  //===--------------------------------------------------------------------===//
284  // AttributeSet Introspection
285  //===--------------------------------------------------------------------===//
286
287  // FIXME: Remove this.
288  uint64_t Raw(unsigned Index) const;
289
290  /// \brief Return a raw pointer that uniquely identifies this attribute list.
291  void *getRawPointer() const {
292    return pImpl;
293  }
294
295  /// \brief Return true if there are no attributes.
296  bool isEmpty() const {
297    return getNumSlots() == 0;
298  }
299
300  /// \brief Return the number of slots used in this attribute list.  This is
301  /// the number of arguments that have an attribute set on them (including the
302  /// function itself).
303  unsigned getNumSlots() const;
304
305  /// \brief Return the index for the given slot.
306  uint64_t getSlotIndex(unsigned Slot) const;
307
308  /// \brief Return the attributes at the given slot.
309  AttributeSet getSlotAttributes(unsigned Slot) const;
310
311  void dump() const;
312};
313
314//===----------------------------------------------------------------------===//
315/// \class
316/// \brief Provide DenseMapInfo for Attribute::AttrKinds. This is used by
317/// AttrBuilder.
318template<> struct DenseMapInfo<Attribute::AttrKind> {
319  static inline Attribute::AttrKind getEmptyKey() {
320    return Attribute::AttrKindEmptyKey;
321  }
322  static inline Attribute::AttrKind getTombstoneKey() {
323    return Attribute::AttrKindTombstoneKey;
324  }
325  static unsigned getHashValue(const Attribute::AttrKind &Val) {
326    return Val * 37U;
327  }
328  static bool isEqual(const Attribute::AttrKind &LHS,
329                      const Attribute::AttrKind &RHS) {
330    return LHS == RHS;
331  }
332};
333
334//===----------------------------------------------------------------------===//
335/// \class
336/// \brief This class is used in conjunction with the Attribute::get method to
337/// create an Attribute object. The object itself is uniquified. The Builder's
338/// value, however, is not. So this can be used as a quick way to test for
339/// equality, presence of attributes, etc.
340class AttrBuilder {
341  DenseSet<Attribute::AttrKind> Attrs;
342  uint64_t Alignment;
343  uint64_t StackAlignment;
344public:
345  AttrBuilder() : Alignment(0), StackAlignment(0) {}
346  explicit AttrBuilder(uint64_t B) : Alignment(0), StackAlignment(0) {
347    addRawValue(B);
348  }
349  AttrBuilder(const Attribute &A) : Alignment(0), StackAlignment(0) {
350    addAttribute(A);
351  }
352  AttrBuilder(AttributeSet AS, unsigned Idx);
353
354  void clear();
355
356  /// \brief Add an attribute to the builder.
357  AttrBuilder &addAttribute(Attribute::AttrKind Val);
358
359  /// \brief Add the Attribute object to the builder.
360  AttrBuilder &addAttribute(Attribute A);
361
362  /// \brief Remove an attribute from the builder.
363  AttrBuilder &removeAttribute(Attribute::AttrKind Val);
364
365  /// \brief Remove the attributes from the builder.
366  AttrBuilder &removeAttributes(AttributeSet A, uint64_t Index);
367
368  /// \brief Return true if the builder has the specified attribute.
369  bool contains(Attribute::AttrKind A) const;
370
371  /// \brief Return true if the builder has IR-level attributes.
372  bool hasAttributes() const;
373
374  /// \brief Return true if the builder has any attribute that's in the
375  /// specified attribute.
376  bool hasAttributes(AttributeSet A, uint64_t Index) const;
377
378  /// \brief Return true if the builder has an alignment attribute.
379  bool hasAlignmentAttr() const;
380
381  /// \brief Retrieve the alignment attribute, if it exists.
382  uint64_t getAlignment() const { return Alignment; }
383
384  /// \brief Retrieve the stack alignment attribute, if it exists.
385  uint64_t getStackAlignment() const { return StackAlignment; }
386
387  /// \brief This turns an int alignment (which must be a power of 2) into the
388  /// form used internally in Attribute.
389  AttrBuilder &addAlignmentAttr(unsigned Align);
390
391  /// \brief This turns an int stack alignment (which must be a power of 2) into
392  /// the form used internally in Attribute.
393  AttrBuilder &addStackAlignmentAttr(unsigned Align);
394
395  typedef DenseSet<Attribute::AttrKind>::iterator       iterator;
396  typedef DenseSet<Attribute::AttrKind>::const_iterator const_iterator;
397
398  iterator begin()             { return Attrs.begin(); }
399  iterator end()               { return Attrs.end(); }
400
401  const_iterator begin() const { return Attrs.begin(); }
402  const_iterator end() const   { return Attrs.end(); }
403
404  /// \brief Remove attributes that are used on functions only.
405  void removeFunctionOnlyAttrs() {
406    removeAttribute(Attribute::NoReturn)
407      .removeAttribute(Attribute::NoUnwind)
408      .removeAttribute(Attribute::ReadNone)
409      .removeAttribute(Attribute::ReadOnly)
410      .removeAttribute(Attribute::NoInline)
411      .removeAttribute(Attribute::AlwaysInline)
412      .removeAttribute(Attribute::OptimizeForSize)
413      .removeAttribute(Attribute::StackProtect)
414      .removeAttribute(Attribute::StackProtectReq)
415      .removeAttribute(Attribute::StackProtectStrong)
416      .removeAttribute(Attribute::NoRedZone)
417      .removeAttribute(Attribute::NoImplicitFloat)
418      .removeAttribute(Attribute::Naked)
419      .removeAttribute(Attribute::InlineHint)
420      .removeAttribute(Attribute::StackAlignment)
421      .removeAttribute(Attribute::UWTable)
422      .removeAttribute(Attribute::NonLazyBind)
423      .removeAttribute(Attribute::ReturnsTwice)
424      .removeAttribute(Attribute::AddressSafety)
425      .removeAttribute(Attribute::MinSize)
426      .removeAttribute(Attribute::NoDuplicate);
427  }
428
429  bool operator==(const AttrBuilder &B);
430  bool operator!=(const AttrBuilder &B) {
431    return !(*this == B);
432  }
433
434  // FIXME: Remove these.
435
436  /// \brief Add the raw value to the internal representation.
437  ///
438  /// N.B. This should be used ONLY for decoding LLVM bitcode!
439  AttrBuilder &addRawValue(uint64_t Val);
440
441  uint64_t Raw() const;
442};
443
444namespace AttributeFuncs {
445
446/// \brief Which attributes cannot be applied to a type.
447AttributeSet typeIncompatible(Type *Ty, uint64_t Index);
448
449/// \brief This returns an integer containing an encoding of all the LLVM
450/// attributes found in the given attribute bitset.  Any change to this encoding
451/// is a breaking change to bitcode compatibility.
452uint64_t encodeLLVMAttributesForBitcode(AttributeSet Attrs, unsigned Index);
453
454/// \brief This fills an AttrBuilder object with the LLVM attributes that have
455/// been decoded from the given integer. This function must stay in sync with
456/// 'encodeLLVMAttributesForBitcode'.
457/// N.B. This should be used only by the bitcode reader!
458void decodeLLVMAttributesForBitcode(LLVMContext &C, AttrBuilder &B,
459                                    uint64_t EncodedAttrs);
460
461} // end AttributeFuncs namespace
462
463} // end llvm namespace
464
465#endif
466