Attributes.h revision 6bdbf061c353295669b6bfc271b948158602d1bc
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, AttrKind Kind); 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 bool operator==(Attribute A) const { return pImpl == A.pImpl; } 138 bool operator!=(Attribute A) const { return pImpl != A.pImpl; } 139 140 /// \brief Less-than operator. Useful for sorting the attributes list. 141 bool operator<(Attribute A) const; 142 143 /// \brief The Attribute is converted to a string of equivalent mnemonic. This 144 /// is, presumably, for writing out the mnemonics for the assembly writer. 145 std::string getAsString() const; 146 147 void Profile(FoldingSetNodeID &ID) const { 148 ID.AddPointer(pImpl); 149 } 150 151 uint64_t Raw() const; 152}; 153 154//===----------------------------------------------------------------------===// 155/// \class 156/// \brief Provide DenseMapInfo for Attribute::AttrKinds. This is used by 157/// AttrBuilder. 158template<> struct DenseMapInfo<Attribute::AttrKind> { 159 static inline Attribute::AttrKind getEmptyKey() { 160 return Attribute::AttrKindEmptyKey; 161 } 162 static inline Attribute::AttrKind getTombstoneKey() { 163 return Attribute::AttrKindTombstoneKey; 164 } 165 static unsigned getHashValue(const Attribute::AttrKind &Val) { 166 return Val * 37U; 167 } 168 static bool isEqual(const Attribute::AttrKind &LHS, 169 const Attribute::AttrKind &RHS) { 170 return LHS == RHS; 171 } 172}; 173 174//===----------------------------------------------------------------------===// 175// AttributeSet Smart Pointer 176//===----------------------------------------------------------------------===// 177 178class AttrBuilder; 179class AttributeSetImpl; 180class AttributeSetNode; 181 182//===----------------------------------------------------------------------===// 183/// \class 184/// \brief This class manages the ref count for the opaque AttributeSetImpl 185/// object and provides accessors for it. 186class AttributeSet { 187public: 188 enum AttrIndex { 189 ReturnIndex = 0U, 190 FunctionIndex = ~0U 191 }; 192private: 193 friend class AttrBuilder; 194 friend class AttributeSetImpl; 195 196 /// \brief The attributes that we are managing. This can be null to represent 197 /// the empty attributes list. 198 AttributeSetImpl *pImpl; 199 200 /// \brief The attributes for the specified index are returned. Attributes 201 /// for the result are denoted with Idx = 0. 202 Attribute getAttributes(unsigned Idx) const; 203 204 /// \brief Create an AttributeSet with the specified parameters in it. 205 static AttributeSet get(LLVMContext &C, 206 ArrayRef<std::pair<unsigned, Attribute> > Attrs); 207 static AttributeSet get(LLVMContext &C, 208 ArrayRef<std::pair<unsigned, 209 AttributeSetNode*> > Attrs); 210 211 static AttributeSet getImpl(LLVMContext &C, 212 ArrayRef<std::pair<unsigned, 213 AttributeSetNode*> > Attrs); 214 215 216 explicit AttributeSet(AttributeSetImpl *LI) : pImpl(LI) {} 217public: 218 AttributeSet() : pImpl(0) {} 219 AttributeSet(const AttributeSet &P) : pImpl(P.pImpl) {} 220 const AttributeSet &operator=(const AttributeSet &RHS) { 221 pImpl = RHS.pImpl; 222 return *this; 223 } 224 225 //===--------------------------------------------------------------------===// 226 // Attribute List Construction and Mutation 227 //===--------------------------------------------------------------------===// 228 229 /// \brief Return an AttributeSet with the specified parameters in it. 230 static AttributeSet get(LLVMContext &C, ArrayRef<AttributeSet> Attrs); 231 static AttributeSet get(LLVMContext &C, unsigned Idx, 232 ArrayRef<Attribute::AttrKind> Kind); 233 static AttributeSet get(LLVMContext &C, unsigned Idx, AttrBuilder &B); 234 235 /// \brief Add an attribute to the attribute set at the given index. Since 236 /// attribute sets are immutable, this returns a new set. 237 AttributeSet addAttribute(LLVMContext &C, unsigned Idx, 238 Attribute::AttrKind Attr) const; 239 240 /// \brief Add attributes to the attribute set at the given index. Since 241 /// attribute sets are immutable, this returns a new set. 242 AttributeSet addAttributes(LLVMContext &C, unsigned Idx, 243 AttributeSet Attrs) const; 244 245 /// \brief Add return attributes to this attribute set. Since attribute sets 246 /// are immutable, this returns a new set. 247 AttributeSet addRetAttributes(LLVMContext &C, AttributeSet Attrs) const { 248 return addAttributes(C, ReturnIndex, Attrs); 249 } 250 251 /// \brief Add function attributes to this attribute set. Since attribute sets 252 /// are immutable, this returns a new set. 253 AttributeSet addFnAttributes(LLVMContext &C, AttributeSet Attrs) const { 254 return addAttributes(C, FunctionIndex, Attrs); 255 } 256 257 /// \brief Remove the specified attribute at the specified index from this 258 /// attribute list. Since attribute lists are immutable, this returns the new 259 /// list. 260 AttributeSet removeAttribute(LLVMContext &C, unsigned Idx, 261 Attribute::AttrKind Attr) const; 262 263 /// \brief Remove the specified attributes at the specified index from this 264 /// attribute list. Since attribute lists are immutable, this returns the new 265 /// list. 266 AttributeSet removeAttributes(LLVMContext &C, unsigned Idx, 267 AttributeSet Attrs) const; 268 269 //===--------------------------------------------------------------------===// 270 // Attribute Set Accessors 271 //===--------------------------------------------------------------------===// 272 273 /// \brief The attributes for the specified index are returned. 274 AttributeSet getParamAttributes(unsigned Idx) const; 275 276 /// \brief The attributes for the ret value are returned. 277 AttributeSet getRetAttributes() const; 278 279 /// \brief The function attributes are returned. 280 AttributeSet getFnAttributes() const; 281 282 /// \brief Return true if the attribute exists at the given index. 283 bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const; 284 285 /// \brief Return true if attribute exists at the given index. 286 bool hasAttributes(unsigned Index) const; 287 288 /// \brief Return the alignment for the specified function parameter. 289 unsigned getParamAlignment(unsigned Idx) const; 290 291 /// \brief Get the stack alignment. 292 unsigned getStackAlignment(unsigned Index) const; 293 294 /// \brief Return the attributes at the index as a string. 295 std::string getAsString(unsigned Index) const; 296 297 uint64_t Raw(unsigned Index) const; 298 299 /// \brief Return true if the specified attribute is set for at least one 300 /// parameter or for the return value. 301 bool hasAttrSomewhere(Attribute::AttrKind Attr) const; 302 303 /// operator==/!= - Provide equality predicates. 304 bool operator==(const AttributeSet &RHS) const { 305 return pImpl == RHS.pImpl; 306 } 307 bool operator!=(const AttributeSet &RHS) const { 308 return pImpl != RHS.pImpl; 309 } 310 311 //===--------------------------------------------------------------------===// 312 // Attribute List Introspection 313 //===--------------------------------------------------------------------===// 314 315 /// \brief Return a raw pointer that uniquely identifies this attribute list. 316 void *getRawPointer() const { 317 return pImpl; 318 } 319 320 // Attributes are stored as a dense set of slots, where there is one slot for 321 // each argument that has an attribute. This allows walking over the dense 322 // set instead of walking the sparse list of attributes. 323 324 /// \brief Return true if there are no attributes. 325 bool isEmpty() const { 326 return pImpl == 0; 327 } 328 329 /// \brief Return the number of slots used in this attribute list. This is 330 /// the number of arguments that have an attribute set on them (including the 331 /// function itself). 332 unsigned getNumSlots() const; 333 334 /// \brief Return the index for the given slot. 335 uint64_t getSlotIndex(unsigned Slot) const; 336 337 /// \brief Return the attributes at the given slot. 338 AttributeSet getSlotAttributes(unsigned Slot) const; 339 340 void dump() const; 341}; 342 343//===----------------------------------------------------------------------===// 344/// \class 345/// \brief This class is used in conjunction with the Attribute::get method to 346/// create an Attribute object. The object itself is uniquified. The Builder's 347/// value, however, is not. So this can be used as a quick way to test for 348/// equality, presence of attributes, etc. 349class AttrBuilder { 350 DenseSet<Attribute::AttrKind> Attrs; 351 uint64_t Alignment; 352 uint64_t StackAlignment; 353public: 354 AttrBuilder() : Alignment(0), StackAlignment(0) {} 355 explicit AttrBuilder(uint64_t B) : Alignment(0), StackAlignment(0) { 356 addRawValue(B); 357 } 358 AttrBuilder(const Attribute &A) : Alignment(0), StackAlignment(0) { 359 addAttributes(A); 360 } 361 AttrBuilder(AttributeSet AS, unsigned Idx); 362 363 void clear(); 364 365 /// \brief Add an attribute to the builder. 366 AttrBuilder &addAttribute(Attribute::AttrKind Val); 367 368 /// \brief Remove an attribute from the builder. 369 AttrBuilder &removeAttribute(Attribute::AttrKind Val); 370 371 /// \brief Add the attributes to the builder. 372 AttrBuilder &addAttributes(Attribute A); 373 374 /// \brief Remove the attributes from the builder. 375 AttrBuilder &removeAttributes(Attribute A); 376 377 /// \brief Add the attributes to the builder. 378 AttrBuilder &addAttributes(AttributeSet A); 379 380 /// \brief Return true if the builder has the specified attribute. 381 bool contains(Attribute::AttrKind A) const; 382 383 /// \brief Return true if the builder has IR-level attributes. 384 bool hasAttributes() const; 385 386 /// \brief Return true if the builder has any attribute that's in the 387 /// specified attribute. 388 bool hasAttributes(const Attribute &A) const; 389 390 /// \brief Return true if the builder has an alignment attribute. 391 bool hasAlignmentAttr() const; 392 393 /// \brief Retrieve the alignment attribute, if it exists. 394 uint64_t getAlignment() const { return Alignment; } 395 396 /// \brief Retrieve the stack alignment attribute, if it exists. 397 uint64_t getStackAlignment() const { return StackAlignment; } 398 399 /// \brief This turns an int alignment (which must be a power of 2) into the 400 /// form used internally in Attribute. 401 AttrBuilder &addAlignmentAttr(unsigned Align); 402 403 /// \brief This turns an int stack alignment (which must be a power of 2) into 404 /// the form used internally in Attribute. 405 AttrBuilder &addStackAlignmentAttr(unsigned Align); 406 407 typedef DenseSet<Attribute::AttrKind>::iterator iterator; 408 typedef DenseSet<Attribute::AttrKind>::const_iterator const_iterator; 409 410 iterator begin() { return Attrs.begin(); } 411 iterator end() { return Attrs.end(); } 412 413 const_iterator begin() const { return Attrs.begin(); } 414 const_iterator end() const { return Attrs.end(); } 415 416 /// \brief Add the raw value to the internal representation. 417 /// 418 /// N.B. This should be used ONLY for decoding LLVM bitcode! 419 AttrBuilder &addRawValue(uint64_t Val); 420 421 /// \brief Remove attributes that are used on functions only. 422 void removeFunctionOnlyAttrs() { 423 removeAttribute(Attribute::NoReturn) 424 .removeAttribute(Attribute::NoUnwind) 425 .removeAttribute(Attribute::ReadNone) 426 .removeAttribute(Attribute::ReadOnly) 427 .removeAttribute(Attribute::NoInline) 428 .removeAttribute(Attribute::AlwaysInline) 429 .removeAttribute(Attribute::OptimizeForSize) 430 .removeAttribute(Attribute::StackProtect) 431 .removeAttribute(Attribute::StackProtectReq) 432 .removeAttribute(Attribute::StackProtectStrong) 433 .removeAttribute(Attribute::NoRedZone) 434 .removeAttribute(Attribute::NoImplicitFloat) 435 .removeAttribute(Attribute::Naked) 436 .removeAttribute(Attribute::InlineHint) 437 .removeAttribute(Attribute::StackAlignment) 438 .removeAttribute(Attribute::UWTable) 439 .removeAttribute(Attribute::NonLazyBind) 440 .removeAttribute(Attribute::ReturnsTwice) 441 .removeAttribute(Attribute::AddressSafety) 442 .removeAttribute(Attribute::MinSize) 443 .removeAttribute(Attribute::NoDuplicate); 444 } 445 446 uint64_t Raw() const; 447 448 bool operator==(const AttrBuilder &B); 449 bool operator!=(const AttrBuilder &B) { 450 return !(*this == B); 451 } 452}; 453 454namespace AttributeFuncs { 455 456/// \brief Which attributes cannot be applied to a type. 457Attribute typeIncompatible(Type *Ty); 458 459/// \brief This returns an integer containing an encoding of all the LLVM 460/// attributes found in the given attribute bitset. Any change to this encoding 461/// is a breaking change to bitcode compatibility. 462uint64_t encodeLLVMAttributesForBitcode(AttributeSet Attrs, unsigned Index); 463 464/// \brief This returns an attribute bitset containing the LLVM attributes that 465/// have been decoded from the given integer. This function must stay in sync 466/// with 'encodeLLVMAttributesForBitcode'. 467Attribute decodeLLVMAttributesForBitcode(LLVMContext &C, 468 uint64_t EncodedAttrs); 469 470} // end AttributeFuncs namespace 471 472} // end llvm namespace 473 474#endif 475