src/llvm/include/llvm/IR/Attributes.h

   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
  28 namespace llvm {
  29
  30 class AttrBuilder;
  31 class AttributeImpl;
  32 class AttributeSetImpl;
  33 class AttributeSetNode;
  34 class Constant;
  35 template<typename T> struct DenseMapInfo;
  36 class LLVMContext;
  37 class 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.
  45 class Attribute {
  46 public:
  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     JumpTable,             ///< Build jump-instruction tables and replace refs.
  79     MinSize,               ///< Function must be optimized for size first
  80     Naked,                 ///< Naked function
  81     Nest,                  ///< Nested function static chain
  82     NoAlias,               ///< Considered to not alias after call
  83     NoBuiltin,             ///< Callee isn't recognized as a builtin
  84     NoCapture,             ///< Function creates no aliases of pointer
  85     NoDuplicate,           ///< Call cannot be duplicated
  86     NoImplicitFloat,       ///< Disable implicit floating point insts
  87     NoInline,              ///< inline=never
  88     NonLazyBind,           ///< Function is called early and/or
  89                            ///< often, so lazy binding isn't worthwhile
  90     NonNull,               ///< Pointer is known to be not null
  91     Dereferenceable,       ///< Pointer is known to be dereferenceable
  92     NoRedZone,             ///< Disable redzone
  93     NoReturn,              ///< Mark the function as not returning
  94     NoUnwind,              ///< Function doesn't unwind stack
  95     OptimizeForSize,       ///< opt_size
  96     OptimizeNone,          ///< Function must not be optimized.
  97     ReadNone,              ///< Function does not access memory
  98     ReadOnly,              ///< Function only reads from memory
  99     Returned,              ///< Return value is always equal to this argument
 100     ReturnsTwice,          ///< Function can return twice
 101     SExt,                  ///< Sign extended before/after call
 102     StackAlignment,        ///< Alignment of stack for function (3 bits)
 103                            ///< stored as log2 of alignment with +1 bias 0
 104                            ///< means unaligned (different from
 105                            ///< alignstack=(1))
 106     StackProtect,          ///< Stack protection.
 107     StackProtectReq,       ///< Stack protection required.
 108     StackProtectStrong,    ///< Strong Stack protection.
 109     StructRet,             ///< Hidden pointer to structure to return
 110     SanitizeAddress,       ///< AddressSanitizer is on.
 111     SanitizeThread,        ///< ThreadSanitizer is on.
 112     SanitizeMemory,        ///< MemorySanitizer is on.
 113     UWTable,               ///< Function must be in a unwind table
 114     ZExt,                  ///< Zero extended before/after call
 115
 116     EndAttrKinds           ///< Sentinal value useful for loops
 117   };
 118 private:
 119   AttributeImpl *pImpl;
 120   Attribute(AttributeImpl *A) : pImpl(A) {}
 121 public:
 122   Attribute() : pImpl(nullptr) {}
 123
 124   //===--------------------------------------------------------------------===//
 125   // Attribute Construction
 126   //===--------------------------------------------------------------------===//
 127
 128   /// \brief Return a uniquified Attribute object.
 129   static Attribute get(LLVMContext &Context, AttrKind Kind, uint64_t Val = 0);
 130   static Attribute get(LLVMContext &Context, StringRef Kind,
 131                        StringRef Val = StringRef());
 132
 133   /// \brief Return a uniquified Attribute object that has the specific
 134   /// alignment set.
 135   static Attribute getWithAlignment(LLVMContext &Context, uint64_t Align);
 136   static Attribute getWithStackAlignment(LLVMContext &Context, uint64_t Align);
 137   static Attribute getWithDereferenceableBytes(LLVMContext &Context,
 138                                               uint64_t Bytes);
 139
 140   //===--------------------------------------------------------------------===//
 141   // Attribute Accessors
 142   //===--------------------------------------------------------------------===//
 143
 144   /// \brief Return true if the attribute is an Attribute::AttrKind type.
 145   bool isEnumAttribute() const;
 146
 147   /// \brief Return true if the attribute is an integer attribute.
 148   bool isIntAttribute() const;
 149
 150   /// \brief Return true if the attribute is a string (target-dependent)
 151   /// attribute.
 152   bool isStringAttribute() const;
 153
 154   /// \brief Return true if the attribute is present.
 155   bool hasAttribute(AttrKind Val) const;
 156
 157   /// \brief Return true if the target-dependent attribute is present.
 158   bool hasAttribute(StringRef Val) const;
 159
 160   /// \brief Return the attribute's kind as an enum (Attribute::AttrKind). This
 161   /// requires the attribute to be an enum or alignment attribute.
 162   Attribute::AttrKind getKindAsEnum() const;
 163
 164   /// \brief Return the attribute's value as an integer. This requires that the
 165   /// attribute be an alignment attribute.
 166   uint64_t getValueAsInt() const;
 167
 168   /// \brief Return the attribute's kind as a string. This requires the
 169   /// attribute to be a string attribute.
 170   StringRef getKindAsString() const;
 171
 172   /// \brief Return the attribute's value as a string. This requires the
 173   /// attribute to be a string attribute.
 174   StringRef getValueAsString() const;
 175
 176   /// \brief Returns the alignment field of an attribute as a byte alignment
 177   /// value.
 178   unsigned getAlignment() const;
 179
 180   /// \brief Returns the stack alignment field of an attribute as a byte
 181   /// alignment value.
 182   unsigned getStackAlignment() const;
 183
 184   /// \brief Returns the number of dereferenceable bytes from the
 185   /// dereferenceable attribute (or zero if unknown).
 186   uint64_t getDereferenceableBytes() const;
 187
 188   /// \brief The Attribute is converted to a string of equivalent mnemonic. This
 189   /// is, presumably, for writing out the mnemonics for the assembly writer.
 190   std::string getAsString(bool InAttrGrp = false) const;
 191
 192   /// \brief Equality and non-equality operators.
 193   bool operator==(Attribute A) const { return pImpl == A.pImpl; }
 194   bool operator!=(Attribute A) const { return pImpl != A.pImpl; }
 195
 196   /// \brief Less-than operator. Useful for sorting the attributes list.
 197   bool operator<(Attribute A) const;
 198
 199   void Profile(FoldingSetNodeID &ID) const {
 200     ID.AddPointer(pImpl);
 201   }
 202 };
 203
 204 //===----------------------------------------------------------------------===//
 205 /// \class
 206 /// \brief This class holds the attributes for a function, its return value, and
 207 /// its parameters. You access the attributes for each of them via an index into
 208 /// the AttributeSet object. The function attributes are at index
 209 /// `AttributeSet::FunctionIndex', the return value is at index
 210 /// `AttributeSet::ReturnIndex', and the attributes for the parameters start at
 211 /// index `1'.
 212 class AttributeSet {
 213 public:
 214   enum AttrIndex : unsigned {
 215     ReturnIndex = 0U,
 216     FunctionIndex = ~0U
 217   };
 218 private:
 219   friend class AttrBuilder;
 220   friend class AttributeSetImpl;
 221   template <typename Ty> friend struct DenseMapInfo;
 222
 223   /// \brief The attributes that we are managing. This can be null to represent
 224   /// the empty attributes list.
 225   AttributeSetImpl *pImpl;
 226
 227   /// \brief The attributes for the specified index are returned.
 228   AttributeSetNode *getAttributes(unsigned Index) const;
 229
 230   /// \brief Create an AttributeSet with the specified parameters in it.
 231   static AttributeSet get(LLVMContext &C,
 232                           ArrayRef<std::pair<unsigned, Attribute> > Attrs);
 233   static AttributeSet get(LLVMContext &C,
 234                           ArrayRef<std::pair<unsigned,
 235                                              AttributeSetNode*> > Attrs);
 236
 237   static AttributeSet getImpl(LLVMContext &C,
 238                               ArrayRef<std::pair<unsigned,
 239                                                  AttributeSetNode*> > Attrs);
 240
 241
 242   explicit AttributeSet(AttributeSetImpl *LI) : pImpl(LI) {}
 243 public:
 244   AttributeSet() : pImpl(nullptr) {}
 245
 246   //===--------------------------------------------------------------------===//
 247   // AttributeSet Construction and Mutation
 248   //===--------------------------------------------------------------------===//
 249
 250   /// \brief Return an AttributeSet with the specified parameters in it.
 251   static AttributeSet get(LLVMContext &C, ArrayRef<AttributeSet> Attrs);
 252   static AttributeSet get(LLVMContext &C, unsigned Index,
 253                           ArrayRef<Attribute::AttrKind> Kind);
 254   static AttributeSet get(LLVMContext &C, unsigned Index, const AttrBuilder &B);
 255
 256   /// \brief Add an attribute to the attribute set at the given index. Since
 257   /// attribute sets are immutable, this returns a new set.
 258   AttributeSet addAttribute(LLVMContext &C, unsigned Index,
 259                             Attribute::AttrKind Attr) const;
 260
 261   /// \brief Add an attribute to the attribute set at the given index. Since
 262   /// attribute sets are immutable, this returns a new set.
 263   AttributeSet addAttribute(LLVMContext &C, unsigned Index,
 264                             StringRef Kind) const;
 265   AttributeSet addAttribute(LLVMContext &C, unsigned Index,
 266                             StringRef Kind, StringRef Value) 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 Index,
 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 Index,
 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 Index,
 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 Index) 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 the attribute exists at the given index.
 305   bool hasAttribute(unsigned Index, StringRef Kind) const;
 306
 307   /// \brief Return true if attribute exists at the given index.
 308   bool hasAttributes(unsigned Index) const;
 309
 310   /// \brief Return true if the specified attribute is set for at least one
 311   /// parameter or for the return value.
 312   bool hasAttrSomewhere(Attribute::AttrKind Attr) const;
 313
 314   /// \brief Return the attribute object that exists at the given index.
 315   Attribute getAttribute(unsigned Index, Attribute::AttrKind Kind) const;
 316
 317   /// \brief Return the attribute object that exists at the given index.
 318   Attribute getAttribute(unsigned Index, StringRef Kind) const;
 319
 320   /// \brief Return the alignment for the specified function parameter.
 321   unsigned getParamAlignment(unsigned Index) const;
 322
 323   /// \brief Get the stack alignment.
 324   unsigned getStackAlignment(unsigned Index) const;
 325
 326   /// \brief Get the number of dereferenceable bytes (or zero if unknown).
 327   uint64_t getDereferenceableBytes(unsigned Index) const;
 328
 329   /// \brief Return the attributes at the index as a string.
 330   std::string getAsString(unsigned Index, bool InAttrGrp = false) const;
 331
 332   typedef ArrayRef<Attribute>::iterator iterator;
 333
 334   iterator begin(unsigned Slot) const;
 335   iterator end(unsigned Slot) const;
 336
 337   /// operator==/!= - Provide equality predicates.
 338   bool operator==(const AttributeSet &RHS) const {
 339     return pImpl == RHS.pImpl;
 340   }
 341   bool operator!=(const AttributeSet &RHS) const {
 342     return pImpl != RHS.pImpl;
 343   }
 344
 345   //===--------------------------------------------------------------------===//
 346   // AttributeSet Introspection
 347   //===--------------------------------------------------------------------===//
 348
 349   // FIXME: Remove this.
 350   uint64_t Raw(unsigned Index) const;
 351
 352   /// \brief Return a raw pointer that uniquely identifies this attribute list.
 353   void *getRawPointer() const {
 354     return pImpl;
 355   }
 356
 357   /// \brief Return true if there are no attributes.
 358   bool isEmpty() const {
 359     return getNumSlots() == 0;
 360   }
 361
 362   /// \brief Return the number of slots used in this attribute list.  This is
 363   /// the number of arguments that have an attribute set on them (including the
 364   /// function itself).
 365   unsigned getNumSlots() const;
 366
 367   /// \brief Return the index for the given slot.
 368   unsigned getSlotIndex(unsigned Slot) const;
 369
 370   /// \brief Return the attributes at the given slot.
 371   AttributeSet getSlotAttributes(unsigned Slot) const;
 372
 373   void dump() const;
 374 };
 375
 376 //===----------------------------------------------------------------------===//
 377 /// \class
 378 /// \brief Provide DenseMapInfo for AttributeSet.
 379 template<> struct DenseMapInfo<AttributeSet> {
 380   static inline AttributeSet getEmptyKey() {
 381     uintptr_t Val = static_cast<uintptr_t>(-1);
 382     Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
 383     return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
 384   }
 385   static inline AttributeSet getTombstoneKey() {
 386     uintptr_t Val = static_cast<uintptr_t>(-2);
 387     Val <<= PointerLikeTypeTraits<void*>::NumLowBitsAvailable;
 388     return AttributeSet(reinterpret_cast<AttributeSetImpl*>(Val));
 389   }
 390   static unsigned getHashValue(AttributeSet AS) {
 391     return (unsigned((uintptr_t)AS.pImpl) >> 4) ^
 392            (unsigned((uintptr_t)AS.pImpl) >> 9);
 393   }
 394   static bool isEqual(AttributeSet LHS, AttributeSet RHS) { return LHS == RHS; }
 395 };
 396
 397 //===----------------------------------------------------------------------===//
 398 /// \class
 399 /// \brief This class is used in conjunction with the Attribute::get method to
 400 /// create an Attribute object. The object itself is uniquified. The Builder's
 401 /// value, however, is not. So this can be used as a quick way to test for
 402 /// equality, presence of attributes, etc.
 403 class AttrBuilder {
 404   std::bitset<Attribute::EndAttrKinds> Attrs;
 405   std::map<std::string, std::string> TargetDepAttrs;
 406   uint64_t Alignment;
 407   uint64_t StackAlignment;
 408   uint64_t DerefBytes;
 409 public:
 410   AttrBuilder() : Attrs(0), Alignment(0), StackAlignment(0), DerefBytes(0) {}
 411   explicit AttrBuilder(uint64_t Val)
 412     : Attrs(0), Alignment(0), StackAlignment(0), DerefBytes(0) {
 413     addRawValue(Val);
 414   }
 415   AttrBuilder(const Attribute &A)
 416     : Attrs(0), Alignment(0), StackAlignment(0), DerefBytes(0) {
 417     addAttribute(A);
 418   }
 419   AttrBuilder(AttributeSet AS, unsigned Idx);
 420
 421   void clear();
 422
 423   /// \brief Add an attribute to the builder.
 424   AttrBuilder &addAttribute(Attribute::AttrKind Val);
 425
 426   /// \brief Add the Attribute object to the builder.
 427   AttrBuilder &addAttribute(Attribute A);
 428
 429   /// \brief Add the target-dependent attribute to the builder.
 430   AttrBuilder &addAttribute(StringRef A, StringRef V = StringRef());
 431
 432   /// \brief Remove an attribute from the builder.
 433   AttrBuilder &removeAttribute(Attribute::AttrKind Val);
 434
 435   /// \brief Remove the attributes from the builder.
 436   AttrBuilder &removeAttributes(AttributeSet A, uint64_t Index);
 437
 438   /// \brief Remove the target-dependent attribute to the builder.
 439   AttrBuilder &removeAttribute(StringRef A);
 440
 441   /// \brief Add the attributes from the builder.
 442   AttrBuilder &merge(const AttrBuilder &B);
 443
 444   /// \brief Return true if the builder has the specified attribute.
 445   bool contains(Attribute::AttrKind A) const {
 446     assert((unsigned)A < Attribute::EndAttrKinds && "Attribute out of range!");
 447     return Attrs[A];
 448   }
 449
 450   /// \brief Return true if the builder has the specified target-dependent
 451   /// attribute.
 452   bool contains(StringRef A) const;
 453
 454   /// \brief Return true if the builder has IR-level attributes.
 455   bool hasAttributes() const;
 456
 457   /// \brief Return true if the builder has any attribute that's in the
 458   /// specified attribute.
 459   bool hasAttributes(AttributeSet A, uint64_t Index) const;
 460
 461   /// \brief Return true if the builder has an alignment attribute.
 462   bool hasAlignmentAttr() const;
 463
 464   /// \brief Retrieve the alignment attribute, if it exists.
 465   uint64_t getAlignment() const { return Alignment; }
 466
 467   /// \brief Retrieve the stack alignment attribute, if it exists.
 468   uint64_t getStackAlignment() const { return StackAlignment; }
 469
 470   /// \brief Retrieve the number of dereferenceable bytes, if the dereferenceable
 471   /// attribute exists (zero is returned otherwise).
 472   uint64_t getDereferenceableBytes() const { return DerefBytes; }
 473
 474   /// \brief This turns an int alignment (which must be a power of 2) into the
 475   /// form used internally in Attribute.
 476   AttrBuilder &addAlignmentAttr(unsigned Align);
 477
 478   /// \brief This turns an int stack alignment (which must be a power of 2) into
 479   /// the form used internally in Attribute.
 480   AttrBuilder &addStackAlignmentAttr(unsigned Align);
 481
 482   /// \brief This turns the number of dereferenceable bytes into the form used
 483   /// internally in Attribute.
 484   AttrBuilder &addDereferenceableAttr(uint64_t Bytes);
 485
 486   /// \brief Return true if the builder contains no target-independent
 487   /// attributes.
 488   bool empty() const { return Attrs.none(); }
 489
 490   // Iterators for target-dependent attributes.
 491   typedef std::pair<std::string, std::string>                td_type;
 492   typedef std::map<std::string, std::string>::iterator       td_iterator;
 493   typedef std::map<std::string, std::string>::const_iterator td_const_iterator;
 494   typedef llvm::iterator_range<td_iterator>                  td_range;
 495   typedef llvm::iterator_range<td_const_iterator>            td_const_range;
 496
 497   td_iterator td_begin()             { return TargetDepAttrs.begin(); }
 498   td_iterator td_end()               { return TargetDepAttrs.end(); }
 499
 500   td_const_iterator td_begin() const { return TargetDepAttrs.begin(); }
 501   td_const_iterator td_end() const   { return TargetDepAttrs.end(); }
 502
 503   td_range td_attrs() { return td_range(td_begin(), td_end()); }
 504   td_const_range td_attrs() const {
 505     return td_const_range(td_begin(), td_end());
 506   }
 507
 508   bool td_empty() const              { return TargetDepAttrs.empty(); }
 509
 510   bool operator==(const AttrBuilder &B);
 511   bool operator!=(const AttrBuilder &B) {
 512     return !(*this == B);
 513   }
 514
 515   // FIXME: Remove this in 4.0.
 516
 517   /// \brief Add the raw value to the internal representation.
 518   AttrBuilder &addRawValue(uint64_t Val);
 519 };
 520
 521 namespace AttributeFuncs {
 522
 523 /// \brief Which attributes cannot be applied to a type.
 524 AttributeSet typeIncompatible(Type *Ty, uint64_t Index);
 525
 526 } // end AttributeFuncs namespace
 527
 528 } // end llvm namespace
 529
 530 #endif