Attributes.h revision c08a5ef6581f2c7550e92d31f63cd65ec29c39e0
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 "llvm/Support/MathExtras.h" 23#include <cassert> 24#include <string> 25 26namespace llvm { 27 28class AttrBuilder; 29class AttributeImpl; 30class Constant; 31class LLVMContext; 32class Type; 33 34//===----------------------------------------------------------------------===// 35/// \class 36/// \brief Functions, function parameters, and return types can have attributes 37/// to indicate how they should be treated by optimizations and code 38/// generation. This class represents one of those attributes. It's light-weight 39/// and should be passed around by-value. 40class Attribute { 41public: 42 /// This enumeration lists the attributes that can be associated with 43 /// parameters, function results or the function itself. 44 /// 45 /// Note: uwtable is about the ABI or the user mandating an entry in the 46 /// unwind table. The nounwind attribute is about an exception passing by the 47 /// function. 48 /// 49 /// In a theoretical system that uses tables for profiling and sjlj for 50 /// exceptions, they would be fully independent. In a normal system that uses 51 /// tables for both, the semantics are: 52 /// 53 /// nil = Needs an entry because an exception might pass by. 54 /// nounwind = No need for an entry 55 /// uwtable = Needs an entry because the ABI says so and because 56 /// an exception might pass by. 57 /// uwtable + nounwind = Needs an entry because the ABI says so. 58 59 enum AttrKind { 60 // IR-Level Attributes 61 None, ///< No attributes have been set 62 AddressSafety, ///< Address safety checking is on. 63 Alignment, ///< Alignment of parameter (5 bits) 64 ///< stored as log2 of alignment with +1 bias 65 ///< 0 means unaligned (different from align(1)) 66 AlwaysInline, ///< inline=always 67 ByVal, ///< Pass structure by value 68 InlineHint, ///< Source said inlining was desirable 69 InReg, ///< Force argument to be passed in register 70 MinSize, ///< Function must be optimized for size first 71 Naked, ///< Naked function 72 Nest, ///< Nested function static chain 73 NoAlias, ///< Considered to not alias after call 74 NoCapture, ///< Function creates no aliases of pointer 75 NoDuplicate, ///< Call cannot be duplicated 76 NoImplicitFloat, ///< Disable implicit floating point insts 77 NoInline, ///< inline=never 78 NonLazyBind, ///< Function is called early and/or 79 ///< often, so lazy binding isn't worthwhile 80 NoRedZone, ///< Disable redzone 81 NoReturn, ///< Mark the function as not returning 82 NoUnwind, ///< Function doesn't unwind stack 83 OptimizeForSize, ///< opt_size 84 ReadNone, ///< Function does not access memory 85 ReadOnly, ///< Function only reads from memory 86 ReturnsTwice, ///< Function can return twice 87 SExt, ///< Sign extended before/after call 88 StackAlignment, ///< Alignment of stack for function (3 bits) 89 ///< stored as log2 of alignment with +1 bias 0 90 ///< means unaligned (different from 91 ///< alignstack=(1)) 92 StackProtect, ///< Stack protection. 93 StackProtectReq, ///< Stack protection required. 94 StackProtectStrong, ///< Strong Stack protection. 95 StructRet, ///< Hidden pointer to structure to return 96 UWTable, ///< Function must be in a unwind table 97 ZExt, ///< Zero extended before/after call 98 99 EndAttrKinds, ///< Sentinal value useful for loops 100 101 AttrKindEmptyKey, ///< Empty key value for DenseMapInfo 102 AttrKindTombstoneKey ///< Tombstone key value for DenseMapInfo 103 }; 104private: 105 AttributeImpl *pImpl; 106 Attribute(AttributeImpl *A) : pImpl(A) {} 107public: 108 Attribute() : pImpl(0) {} 109 110 /// \brief Return a uniquified Attribute object. 111 static Attribute get(LLVMContext &Context, ArrayRef<AttrKind> Kinds); 112 static Attribute get(LLVMContext &Context, AttrBuilder &B); 113 114 /// \brief Return a uniquified Attribute object that has the specific 115 /// alignment set. 116 static Attribute getWithAlignment(LLVMContext &Context, uint64_t Align); 117 static Attribute getWithStackAlignment(LLVMContext &Context, uint64_t Align); 118 119 /// \brief Return true if the attribute is present. 120 bool hasAttribute(AttrKind Val) const; 121 122 /// \brief Return true if attributes exist 123 bool hasAttributes() const; 124 125 /// \brief Returns the alignment field of an attribute as a byte alignment 126 /// value. 127 unsigned getAlignment() const; 128 129 /// \brief Returns the stack alignment field of an attribute as a byte 130 /// alignment value. 131 unsigned getStackAlignment() const; 132 133 /// \brief Equality and non-equality query methods. 134 bool operator==(AttrKind K) const; 135 bool operator!=(AttrKind K) const; 136 137 /// \brief Less-than operator. Useful for sorting the attributes list. 138 bool operator<(Attribute A) const; 139 140 /// \brief The Attribute is converted to a string of equivalent mnemonic. This 141 /// is, presumably, for writing out the mnemonics for the assembly writer. 142 std::string getAsString() const; 143 144 void Profile(FoldingSetNodeID &ID) const { 145 ID.AddPointer(pImpl); 146 } 147 148 uint64_t Raw() const; 149}; 150 151//===----------------------------------------------------------------------===// 152/// \class 153/// \brief Provide DenseMapInfo for Attribute::AttrKinds. This is used by 154/// AttrBuilder. 155template<> struct DenseMapInfo<Attribute::AttrKind> { 156 static inline Attribute::AttrKind getEmptyKey() { 157 return Attribute::AttrKindEmptyKey; 158 } 159 static inline Attribute::AttrKind getTombstoneKey() { 160 return Attribute::AttrKindTombstoneKey; 161 } 162 static unsigned getHashValue(const Attribute::AttrKind &Val) { 163 return Val * 37U; 164 } 165 static bool isEqual(const Attribute::AttrKind &LHS, 166 const Attribute::AttrKind &RHS) { 167 return LHS == RHS; 168 } 169}; 170 171//===----------------------------------------------------------------------===// 172// AttributeSet Smart Pointer 173//===----------------------------------------------------------------------===// 174 175class AttrBuilder; 176class AttributeSetImpl; 177 178//===----------------------------------------------------------------------===// 179/// \class 180/// \brief This is just a pair of values to associate a set of attributes with 181/// an index. 182struct AttributeWithIndex { 183 Attribute Attrs; ///< The attributes that are set, or'd together. 184 unsigned Index; ///< Index of the parameter for which the attributes apply. 185 186 static AttributeWithIndex get(unsigned Idx, Attribute Attrs) { 187 AttributeWithIndex P; 188 P.Index = Idx; 189 P.Attrs = Attrs; 190 return P; 191 } 192}; 193 194//===----------------------------------------------------------------------===// 195/// \class 196/// \brief This class manages the ref count for the opaque AttributeSetImpl 197/// object and provides accessors for it. 198class AttributeSet { 199public: 200 enum AttrIndex { 201 ReturnIndex = 0U, 202 FunctionIndex = ~0U 203 }; 204private: 205 friend class AttrBuilder; 206 friend class AttributeSetImpl; 207 208 /// \brief The attributes that we are managing. This can be null to represent 209 /// the empty attributes list. 210 AttributeSetImpl *pImpl; 211 212 /// \brief The attributes for the specified index are returned. Attributes 213 /// for the result are denoted with Idx = 0. 214 Attribute getAttributes(unsigned Idx) const; 215 216 /// \brief Add the specified attribute at the specified index to this 217 /// attribute list. Since attribute lists are immutable, this returns the new 218 /// list. 219 AttributeSet addAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const; 220 221 /// \brief Remove the specified attribute at the specified index from this 222 /// attribute list. Since attribute lists are immutable, this returns the new 223 /// list. 224 AttributeSet removeAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const; 225 226 /// \brief Create an AttributeSet from the AttributeWithIndex structures. 227 /// N.B. this is only temporary. It will be disappearing in the future. 228 static AttributeSet get(LLVMContext &C, ArrayRef<AttributeWithIndex> Attrs); 229 230 explicit AttributeSet(AttributeSetImpl *LI) : pImpl(LI) {} 231public: 232 AttributeSet() : pImpl(0) {} 233 AttributeSet(const AttributeSet &P) : pImpl(P.pImpl) {} 234 const AttributeSet &operator=(const AttributeSet &RHS); 235 236 //===--------------------------------------------------------------------===// 237 // Attribute List Construction and Mutation 238 //===--------------------------------------------------------------------===// 239 240 /// \brief Return an AttributeSet with the specified parameters in it. 241 static AttributeSet get(LLVMContext &C, ArrayRef<AttributeSet> Attrs); 242 static AttributeSet get(LLVMContext &C, unsigned Idx, 243 ArrayRef<Attribute::AttrKind> Kind); 244 static AttributeSet get(LLVMContext &C, unsigned Idx, AttrBuilder &B); 245 246 /// \brief Add an attribute to the attribute set at the given index. Since 247 /// attribute sets are immutable, this returns a new set. 248 AttributeSet addAttribute(LLVMContext &C, unsigned Idx, 249 Attribute::AttrKind Attr) const; 250 251 /// \brief Add attributes to the attribute set at the given index. Since 252 /// attribute sets are immutable, this returns a new set. 253 AttributeSet addAttributes(LLVMContext &C, unsigned Idx, 254 AttributeSet Attrs) const; 255 256 /// \brief Add return attributes to this attribute set. Since attribute sets 257 /// are immutable, this returns a new set. 258 AttributeSet addRetAttributes(LLVMContext &C, AttributeSet Attrs) const { 259 return addAttributes(C, ReturnIndex, Attrs); 260 } 261 262 /// \brief Add function attributes to this attribute set. Since attribute sets 263 /// are immutable, this returns a new set. 264 AttributeSet addFnAttributes(LLVMContext &C, AttributeSet Attrs) const { 265 return addAttributes(C, FunctionIndex, Attrs); 266 } 267 268 /// \brief Remove the specified attribute at the specified index from this 269 /// attribute list. Since attribute lists are immutable, this returns the new 270 /// list. 271 AttributeSet removeAttribute(LLVMContext &C, unsigned Idx, 272 Attribute::AttrKind Attr) const; 273 274 /// \brief Remove the specified attributes at the specified index from this 275 /// attribute list. Since attribute lists are immutable, this returns the new 276 /// list. 277 AttributeSet removeAttributes(LLVMContext &C, unsigned Idx, 278 AttributeSet Attrs) const; 279 280 //===--------------------------------------------------------------------===// 281 // Attribute List Accessors 282 //===--------------------------------------------------------------------===// 283 284 /// \brief The attributes for the specified index are returned. 285 AttributeSet getParamAttributes(unsigned Idx) 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 the alignment for the specified function parameter. 294 unsigned getParamAlignment(unsigned Idx) const; 295 296 /// \brief Return true if the attribute exists at the given index. 297 bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const; 298 299 /// \brief Return true if attribute exists at the given index. 300 bool hasAttributes(unsigned Index) const; 301 302 /// \brief Returns the alignment field of an attribute as a byte alignment 303 /// value. 304 unsigned getAlignment(unsigned Index) const; 305 306 /// \brief Get the stack alignment. 307 unsigned getStackAlignment(unsigned Index) const; 308 309 /// \brief Return the attributes at the index as a string. 310 std::string getAsString(unsigned Index) const; 311 312 uint64_t Raw(unsigned Index) const; 313 314 /// \brief Return true if the specified attribute is set for at least one 315 /// parameter or for the return value. 316 bool hasAttrSomewhere(Attribute::AttrKind Attr) const; 317 318 /// operator==/!= - Provide equality predicates. 319 bool operator==(const AttributeSet &RHS) const { 320 return pImpl == RHS.pImpl; 321 } 322 bool operator!=(const AttributeSet &RHS) const { 323 return pImpl != RHS.pImpl; 324 } 325 326 //===--------------------------------------------------------------------===// 327 // Attribute List Introspection 328 //===--------------------------------------------------------------------===// 329 330 /// \brief Return a raw pointer that uniquely identifies this attribute list. 331 void *getRawPointer() const { 332 return pImpl; 333 } 334 335 // Attributes are stored as a dense set of slots, where there is one slot for 336 // each argument that has an attribute. This allows walking over the dense 337 // set instead of walking the sparse list of attributes. 338 339 /// \brief Return true if there are no attributes. 340 bool isEmpty() const { 341 return pImpl == 0; 342 } 343 344 /// \brief Return the number of slots used in this attribute list. This is 345 /// the number of arguments that have an attribute set on them (including the 346 /// function itself). 347 unsigned getNumSlots() const; 348 349 /// \brief Return the index for the given slot. 350 unsigned getSlotIndex(unsigned Slot) const; 351 352 /// \brief Return the attributes at the given slot. 353 AttributeSet getSlotAttributes(unsigned Slot) const; 354 355 void dump() const; 356}; 357 358//===----------------------------------------------------------------------===// 359/// \class 360/// \brief This class is used in conjunction with the Attribute::get method to 361/// create an Attribute object. The object itself is uniquified. The Builder's 362/// value, however, is not. So this can be used as a quick way to test for 363/// equality, presence of attributes, etc. 364class AttrBuilder { 365 DenseSet<Attribute::AttrKind> Attrs; 366 uint64_t Alignment; 367 uint64_t StackAlignment; 368public: 369 AttrBuilder() : Alignment(0), StackAlignment(0) {} 370 explicit AttrBuilder(uint64_t B) : Alignment(0), StackAlignment(0) { 371 addRawValue(B); 372 } 373 AttrBuilder(const Attribute &A) : Alignment(0), StackAlignment(0) { 374 addAttributes(A); 375 } 376 AttrBuilder(AttributeSet AS, unsigned Idx); 377 378 void clear(); 379 380 /// \brief Add an attribute to the builder. 381 AttrBuilder &addAttribute(Attribute::AttrKind Val); 382 383 /// \brief Remove an attribute from the builder. 384 AttrBuilder &removeAttribute(Attribute::AttrKind Val); 385 386 /// \brief Add the attributes from A to the builder. 387 AttrBuilder &addAttributes(const Attribute &A); 388 389 /// \brief Remove the attributes from A from the builder. 390 AttrBuilder &removeAttributes(const Attribute &A); 391 392 /// \brief Return true if the builder has the specified attribute. 393 bool contains(Attribute::AttrKind A) const; 394 395 /// \brief Return true if the builder has IR-level attributes. 396 bool hasAttributes() const; 397 398 /// \brief Return true if the builder has any attribute that's in the 399 /// specified attribute. 400 bool hasAttributes(const Attribute &A) const; 401 402 /// \brief Return true if the builder has an alignment attribute. 403 bool hasAlignmentAttr() const; 404 405 /// \brief Retrieve the alignment attribute, if it exists. 406 uint64_t getAlignment() const { return Alignment; } 407 408 /// \brief Retrieve the stack alignment attribute, if it exists. 409 uint64_t getStackAlignment() const { return StackAlignment; } 410 411 /// \brief This turns an int alignment (which must be a power of 2) into the 412 /// form used internally in Attribute. 413 AttrBuilder &addAlignmentAttr(unsigned Align); 414 415 /// \brief This turns an int stack alignment (which must be a power of 2) into 416 /// the form used internally in Attribute. 417 AttrBuilder &addStackAlignmentAttr(unsigned Align); 418 419 typedef DenseSet<Attribute::AttrKind>::iterator iterator; 420 typedef DenseSet<Attribute::AttrKind>::const_iterator const_iterator; 421 422 iterator begin() { return Attrs.begin(); } 423 iterator end() { return Attrs.end(); } 424 425 const_iterator begin() const { return Attrs.begin(); } 426 const_iterator end() const { return Attrs.end(); } 427 428 /// \brief Add the raw value to the internal representation. 429 /// 430 /// N.B. This should be used ONLY for decoding LLVM bitcode! 431 AttrBuilder &addRawValue(uint64_t Val); 432 433 /// \brief Remove attributes that are used on functions only. 434 void removeFunctionOnlyAttrs() { 435 removeAttribute(Attribute::NoReturn) 436 .removeAttribute(Attribute::NoUnwind) 437 .removeAttribute(Attribute::ReadNone) 438 .removeAttribute(Attribute::ReadOnly) 439 .removeAttribute(Attribute::NoInline) 440 .removeAttribute(Attribute::AlwaysInline) 441 .removeAttribute(Attribute::OptimizeForSize) 442 .removeAttribute(Attribute::StackProtect) 443 .removeAttribute(Attribute::StackProtectReq) 444 .removeAttribute(Attribute::StackProtectStrong) 445 .removeAttribute(Attribute::NoRedZone) 446 .removeAttribute(Attribute::NoImplicitFloat) 447 .removeAttribute(Attribute::Naked) 448 .removeAttribute(Attribute::InlineHint) 449 .removeAttribute(Attribute::StackAlignment) 450 .removeAttribute(Attribute::UWTable) 451 .removeAttribute(Attribute::NonLazyBind) 452 .removeAttribute(Attribute::ReturnsTwice) 453 .removeAttribute(Attribute::AddressSafety) 454 .removeAttribute(Attribute::MinSize) 455 .removeAttribute(Attribute::NoDuplicate); 456 } 457 458 uint64_t Raw() const; 459 460 bool operator==(const AttrBuilder &B); 461 bool operator!=(const AttrBuilder &B) { 462 return !(*this == B); 463 } 464}; 465 466namespace AttributeFuncs { 467 468/// \brief Which attributes cannot be applied to a type. 469Attribute typeIncompatible(Type *Ty); 470 471/// \brief This returns an integer containing an encoding of all the LLVM 472/// attributes found in the given attribute bitset. Any change to this encoding 473/// is a breaking change to bitcode compatibility. 474uint64_t encodeLLVMAttributesForBitcode(AttributeSet Attrs, unsigned Index); 475 476/// \brief This returns an attribute bitset containing the LLVM attributes that 477/// have been decoded from the given integer. This function must stay in sync 478/// with 'encodeLLVMAttributesForBitcode'. 479Attribute decodeLLVMAttributesForBitcode(LLVMContext &C, 480 uint64_t EncodedAttrs); 481 482} // end AttributeFuncs namespace 483 484} // end llvm namespace 485 486#endif 487