Attributes.h revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f 
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    InAlloca,              ///< Pass structure in an alloca
75    Cold,                  ///< Marks function as being in a cold path.
76    InlineHint,            ///< Source said inlining was desirable
77    InReg,                 ///< Force argument to be passed in register
78    MinSize,               ///< Function must be optimized for size first
79    Naked,                 ///< Naked function
80    Nest,                  ///< Nested function static chain
81    NoAlias,               ///< Considered to not alias after call
82    NoBuiltin,             ///< Callee isn't recognized as a builtin
83    NoCapture,             ///< Function creates no aliases of pointer
84    NoDuplicate,           ///< Call cannot be duplicated
85    NoImplicitFloat,       ///< Disable implicit floating point insts
86    NoInline,              ///< inline=never
87    NonLazyBind,           ///< Function is called early and/or
88                           ///< often, so lazy binding isn't worthwhile
89    NonNull,               ///< Pointer is known to be not null
90    NoRedZone,             ///< Disable redzone
91    NoReturn,              ///< Mark the function as not returning
92    NoUnwind,              ///< Function doesn't unwind stack
93    OptimizeForSize,       ///< opt_size
94    OptimizeNone,          ///< Function must not be optimized.
95    ReadNone,              ///< Function does not access memory
96    ReadOnly,              ///< Function only reads from memory
97    Returned,              ///< Return value is always equal to this argument
98    ReturnsTwice,          ///< Function can return twice
99    SExt,                  ///< Sign extended before/after call
100    StackAlignment,        ///< Alignment of stack for function (3 bits)
101                           ///< stored as log2 of alignment with +1 bias 0
102                           ///< means unaligned (different from
103                           ///< alignstack=(1))
104    StackProtect,          ///< Stack protection.
105    StackProtectReq,       ///< Stack protection required.
106    StackProtectStrong,    ///< Strong Stack protection.
107    StructRet,             ///< Hidden pointer to structure to return
108    SanitizeAddress,       ///< AddressSanitizer is on.
109    SanitizeThread,        ///< ThreadSanitizer is on.
110    SanitizeMemory,        ///< MemorySanitizer is on.
111    UWTable,               ///< Function must be in a unwind table
112    ZExt,                  ///< Zero extended before/after call
113
114    EndAttrKinds           ///< Sentinal value useful for loops
115  };
116private:
117  AttributeImpl *pImpl;
118  Attribute(AttributeImpl *A) : pImpl(A) {}
119public:
120  Attribute() : pImpl(nullptr) {}
121
122  //===--------------------------------------------------------------------===//
123  // Attribute Construction
124  //===--------------------------------------------------------------------===//
125
126  /// \brief Return a uniquified Attribute object.
127  static Attribute get(LLVMContext &Context, AttrKind Kind, uint64_t Val = 0);
128  static Attribute get(LLVMContext &Context, StringRef Kind,
129                       StringRef Val = StringRef());
130
131  /// \brief Return a uniquified Attribute object that has the specific
132  /// alignment set.
133  static Attribute getWithAlignment(LLVMContext &Context, uint64_t Align);
134  static Attribute getWithStackAlignment(LLVMContext &Context, uint64_t Align);
135
136  //===--------------------------------------------------------------------===//
137  // Attribute Accessors
138  //===--------------------------------------------------------------------===//
139
140  /// \brief Return true if the attribute is an Attribute::AttrKind type.
141  bool isEnumAttribute() const;
142
143  /// \brief Return true if the attribute is an alignment attribute.
144  bool isAlignAttribute() const;
145
146  /// \brief Return true if the attribute is a string (target-dependent)
147  /// attribute.
148  bool isStringAttribute() const;
149
150  /// \brief Return true if the attribute is present.
151  bool hasAttribute(AttrKind Val) const;
152
153  /// \brief Return true if the target-dependent attribute is present.
154  bool hasAttribute(StringRef Val) const;
155
156  /// \brief Return the attribute's kind as an enum (Attribute::AttrKind). This
157  /// requires the attribute to be an enum or alignment attribute.
158  Attribute::AttrKind getKindAsEnum() const;
159
160  /// \brief Return the attribute's value as an integer. This requires that the
161  /// attribute be an alignment attribute.
162  uint64_t getValueAsInt() const;
163
164  /// \brief Return the attribute's kind as a string. This requires the
165  /// attribute to be a string attribute.
166  StringRef getKindAsString() const;
167
168  /// \brief Return the attribute's value as a string. This requires the
169  /// attribute to be a string attribute.
170  StringRef getValueAsString() const;
171
172  /// \brief Returns the alignment field of an attribute as a byte alignment
173  /// value.
174  unsigned getAlignment() const;
175
176  /// \brief Returns the stack alignment field of an attribute as a byte
177  /// alignment value.
178  unsigned getStackAlignment() const;
179
180  /// \brief The Attribute is converted to a string of equivalent mnemonic. This
181  /// is, presumably, for writing out the mnemonics for the assembly writer.
182  std::string getAsString(bool InAttrGrp = false) const;
183
184  /// \brief Equality and non-equality operators.
185  bool operator==(Attribute A) const { return pImpl == A.pImpl; }
186  bool operator!=(Attribute A) const { return pImpl != A.pImpl; }
187
188  /// \brief Less-than operator. Useful for sorting the attributes list.
189  bool operator<(Attribute A) const;
190
191  void Profile(FoldingSetNodeID &ID) const {
192    ID.AddPointer(pImpl);
193  }
194};
195
196//===----------------------------------------------------------------------===//
197/// \class
198/// \brief This class holds the attributes for a function, its return value, and
199/// its parameters. You access the attributes for each of them via an index into
200/// the AttributeSet object. The function attributes are at index
201/// `AttributeSet::FunctionIndex', the return value is at index
202/// `AttributeSet::ReturnIndex', and the attributes for the parameters start at
203/// index `1'.
204class AttributeSet {
205public:
206  enum AttrIndex : unsigned {
207    ReturnIndex = 0U,
208    FunctionIndex = ~0U
209  };
210private:
211  friend class AttrBuilder;
212  friend class AttributeSetImpl;
213  template <typename Ty> friend struct DenseMapInfo;
214
215  /// \brief The attributes that we are managing. This can be null to represent
216  /// the empty attributes list.
217  AttributeSetImpl *pImpl;
218
219  /// \brief The attributes for the specified index are returned.
220  AttributeSetNode *getAttributes(unsigned Index) const;
221
222  /// \brief Create an AttributeSet with the specified parameters in it.
223  static AttributeSet get(LLVMContext &C,
224                          ArrayRef<std::pair<unsigned, Attribute> > Attrs);
225  static AttributeSet get(LLVMContext &C,
226                          ArrayRef<std::pair<unsigned,
227                                             AttributeSetNode*> > Attrs);
228
229  static AttributeSet getImpl(LLVMContext &C,
230                              ArrayRef<std::pair<unsigned,
231                                                 AttributeSetNode*> > Attrs);
232
233
234  explicit AttributeSet(AttributeSetImpl *LI) : pImpl(LI) {}
235public:
236  AttributeSet() : pImpl(nullptr) {}
237
238  //===--------------------------------------------------------------------===//
239  // AttributeSet Construction and Mutation
240  //===--------------------------------------------------------------------===//
241
242  /// \brief Return an AttributeSet with the specified parameters in it.
243  static AttributeSet get(LLVMContext &C, ArrayRef<AttributeSet> Attrs);
244  static AttributeSet get(LLVMContext &C, unsigned Index,
245                          ArrayRef<Attribute::AttrKind> Kind);
246  static AttributeSet get(LLVMContext &C, unsigned Index, const AttrBuilder &B);
247
248  /// \brief Add an attribute to the attribute set at the given index. Since
249  /// attribute sets are immutable, this returns a new set.
250  AttributeSet addAttribute(LLVMContext &C, unsigned Index,
251                            Attribute::AttrKind Attr) const;
252
253  /// \brief Add an attribute to the attribute set at the given index. Since
254  /// attribute sets are immutable, this returns a new set.
255  AttributeSet addAttribute(LLVMContext &C, unsigned Index,
256                            StringRef Kind) const;
257  AttributeSet addAttribute(LLVMContext &C, unsigned Index,
258                            StringRef Kind, StringRef Value) const;
259
260  /// \brief Add attributes to the attribute set at the given index. Since
261  /// attribute sets are immutable, this returns a new set.
262  AttributeSet addAttributes(LLVMContext &C, unsigned Index,
263                             AttributeSet Attrs) const;
264
265  /// \brief Remove the specified attribute at the specified index from this
266  /// attribute list. Since attribute lists are immutable, this returns the new
267  /// list.
268  AttributeSet removeAttribute(LLVMContext &C, unsigned Index,
269                               Attribute::AttrKind Attr) const;
270
271  /// \brief Remove the specified attributes at the specified index from this
272  /// attribute list. Since attribute lists are immutable, this returns the new
273  /// list.
274  AttributeSet removeAttributes(LLVMContext &C, unsigned Index,
275                                AttributeSet Attrs) const;
276
277  //===--------------------------------------------------------------------===//
278  // AttributeSet Accessors
279  //===--------------------------------------------------------------------===//
280
281  /// \brief Retrieve the LLVM context.
282  LLVMContext &getContext() const;
283
284  /// \brief The attributes for the specified index are returned.
285  AttributeSet getParamAttributes(unsigned Index) const;
286
287  /// \brief The attributes for the ret value are returned.
288  AttributeSet getRetAttributes() const;
289
290  /// \brief The function attributes are returned.
291  AttributeSet getFnAttributes() const;
292
293  /// \brief Return true if the attribute exists at the given index.
294  bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const;
295
296  /// \brief Return true if the attribute exists at the given index.
297  bool hasAttribute(unsigned Index, StringRef Kind) const;
298
299  /// \brief Return true if attribute exists at the given index.
300  bool hasAttributes(unsigned Index) const;
301
302  /// \brief Return true if the specified attribute is set for at least one
303  /// parameter or for the return value.
304  bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
305
306  /// \brief Return the attribute object that exists at the given index.
307  Attribute getAttribute(unsigned Index, Attribute::AttrKind Kind) const;
308
309  /// \brief Return the attribute object that exists at the given index.
310  Attribute getAttribute(unsigned Index, StringRef Kind) const;
311
312  /// \brief Return the alignment for the specified function parameter.
313  unsigned getParamAlignment(unsigned Index) const;
314
315  /// \brief Get the stack alignment.
316  unsigned getStackAlignment(unsigned Index) const;
317
318  /// \brief Return the attributes at the index as a string.
319  std::string getAsString(unsigned Index, bool InAttrGrp = false) const;
320
321  typedef ArrayRef<Attribute>::iterator iterator;
322
323  iterator begin(unsigned Slot) const;
324  iterator end(unsigned Slot) const;
325
326  /// operator==/!= - Provide equality predicates.
327  bool operator==(const AttributeSet &RHS) const {
328    return pImpl == RHS.pImpl;
329  }
330  bool operator!=(const AttributeSet &RHS) const {
331    return pImpl != RHS.pImpl;
332  }
333
334  //===--------------------------------------------------------------------===//
335  // AttributeSet Introspection
336  //===--------------------------------------------------------------------===//
337
338  // FIXME: Remove this.
339  uint64_t Raw(unsigned Index) const;
340
341  /// \brief Return a raw pointer that uniquely identifies this attribute list.
342  void *getRawPointer() const {
343    return pImpl;
344  }
345
346  /// \brief Return true if there are no attributes.
347  bool isEmpty() const {
348    return getNumSlots() == 0;
349  }
350
351  /// \brief Return the number of slots used in this attribute list.  This is
352  /// the number of arguments that have an attribute set on them (including the
353  /// function itself).
354  unsigned getNumSlots() const;
355
356  /// \brief Return the index for the given slot.
357  unsigned getSlotIndex(unsigned Slot) const;
358
359  /// \brief Return the attributes at the given slot.
360  AttributeSet getSlotAttributes(unsigned Slot) const;
361
362  void dump() const;
363};
364
365//===----------------------------------------------------------------------===//
366/// \class
367/// \brief Provide DenseMapInfo for AttributeSet.
368template<> struct DenseMapInfo<AttributeSet> {
369  static inline AttributeSet getEmptyKey() {
370    uintptr_t Val = static_cast<uintptr_t>(-1);
371    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
372    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
373  }
374  static inline AttributeSet getTombstoneKey() {
375    uintptr_t Val = static_cast<uintptr_t>(-2);
376    Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
377    return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
378  }
379  static unsigned getHashValue(AttributeSet AS) {
380    return (unsigned((uintptr_t)AS.pImpl) >> 4) ^
381           (unsigned((uintptr_t)AS.pImpl) >> 9);
382  }
383  static bool isEqual(AttributeSet LHS, AttributeSet RHS) { return LHS == RHS; }
384};
385
386//===----------------------------------------------------------------------===//
387/// \class
388/// \brief This class is used in conjunction with the Attribute::get method to
389/// create an Attribute object. The object itself is uniquified. The Builder's
390/// value, however, is not. So this can be used as a quick way to test for
391/// equality, presence of attributes, etc.
392class AttrBuilder {
393  std::bitset<Attribute::EndAttrKinds> Attrs;
394  std::map<std::string, std::string> TargetDepAttrs;
395  uint64_t Alignment;
396  uint64_t StackAlignment;
397public:
398  AttrBuilder() : Attrs(0), Alignment(0), StackAlignment(0) {}
399  explicit AttrBuilder(uint64_t Val)
400    : Attrs(0), Alignment(0), StackAlignment(0) {
401    addRawValue(Val);
402  }
403  AttrBuilder(const Attribute &A) : Attrs(0), Alignment(0), StackAlignment(0) {
404    addAttribute(A);
405  }
406  AttrBuilder(AttributeSet AS, unsigned Idx);
407
408  void clear();
409
410  /// \brief Add an attribute to the builder.
411  AttrBuilder &addAttribute(Attribute::AttrKind Val);
412
413  /// \brief Add the Attribute object to the builder.
414  AttrBuilder &addAttribute(Attribute A);
415
416  /// \brief Add the target-dependent attribute to the builder.
417  AttrBuilder &addAttribute(StringRef A, StringRef V = StringRef());
418
419  /// \brief Remove an attribute from the builder.
420  AttrBuilder &removeAttribute(Attribute::AttrKind Val);
421
422  /// \brief Remove the attributes from the builder.
423  AttrBuilder &removeAttributes(AttributeSet A, uint64_t Index);
424
425  /// \brief Remove the target-dependent attribute to the builder.
426  AttrBuilder &removeAttribute(StringRef A);
427
428  /// \brief Add the attributes from the builder.
429  AttrBuilder &merge(const AttrBuilder &B);
430
431  /// \brief Return true if the builder has the specified attribute.
432  bool contains(Attribute::AttrKind A) const {
433    assert((unsigned)A < Attribute::EndAttrKinds && "Attribute out of range!");
434    return Attrs[A];
435  }
436
437  /// \brief Return true if the builder has the specified target-dependent
438  /// attribute.
439  bool contains(StringRef A) const;
440
441  /// \brief Return true if the builder has IR-level attributes.
442  bool hasAttributes() const;
443
444  /// \brief Return true if the builder has any attribute that's in the
445  /// specified attribute.
446  bool hasAttributes(AttributeSet A, uint64_t Index) const;
447
448  /// \brief Return true if the builder has an alignment attribute.
449  bool hasAlignmentAttr() const;
450
451  /// \brief Retrieve the alignment attribute, if it exists.
452  uint64_t getAlignment() const { return Alignment; }
453
454  /// \brief Retrieve the stack alignment attribute, if it exists.
455  uint64_t getStackAlignment() const { return StackAlignment; }
456
457  /// \brief This turns an int alignment (which must be a power of 2) into the
458  /// form used internally in Attribute.
459  AttrBuilder &addAlignmentAttr(unsigned Align);
460
461  /// \brief This turns an int stack alignment (which must be a power of 2) into
462  /// the form used internally in Attribute.
463  AttrBuilder &addStackAlignmentAttr(unsigned Align);
464
465  /// \brief Return true if the builder contains no target-independent
466  /// attributes.
467  bool empty() const { return Attrs.none(); }
468
469  // Iterators for target-dependent attributes.
470  typedef std::pair<std::string, std::string>                td_type;
471  typedef std::map<std::string, std::string>::iterator       td_iterator;
472  typedef std::map<std::string, std::string>::const_iterator td_const_iterator;
473  typedef llvm::iterator_range<td_iterator>                  td_range;
474  typedef llvm::iterator_range<td_const_iterator>            td_const_range;
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  td_range td_attrs() { return td_range(td_begin(), td_end()); }
483  td_const_range td_attrs() const {
484    return td_const_range(td_begin(), td_end());
485  }
486
487  bool td_empty() const              { return TargetDepAttrs.empty(); }
488
489  bool operator==(const AttrBuilder &B);
490  bool operator!=(const AttrBuilder &B) {
491    return !(*this == B);
492  }
493
494  // FIXME: Remove this in 4.0.
495
496  /// \brief Add the raw value to the internal representation.
497  AttrBuilder &addRawValue(uint64_t Val);
498};
499
500namespace AttributeFuncs {
501
502/// \brief Which attributes cannot be applied to a type.
503AttributeSet typeIncompatible(Type *Ty, uint64_t Index);
504
505} // end AttributeFuncs namespace
506
507} // end llvm namespace
508
509#endif
510