Attributes.h revision e4e85f17564c28cd571dda30146c3f310521acf0
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/Support/MathExtras.h" 22#include <cassert> 23#include <string> 24 25namespace llvm { 26 27class AttrBuilder; 28class AttributeImpl; 29class Constant; 30class LLVMContext; 31class Type; 32 33//===----------------------------------------------------------------------===// 34/// \class 35/// \brief Functions, function parameters, and return types can have attributes 36/// to indicate how they should be treated by optimizations and code 37/// generation. This class represents one of those attributes. It's light-weight 38/// and should be passed around by-value. 39class Attribute { 40public: 41 /// This enumeration lists the attributes that can be associated with 42 /// parameters, function results or the function itself. 43 /// 44 /// Note: uwtable is about the ABI or the user mandating an entry in the 45 /// unwind table. The nounwind attribute is about an exception passing by the 46 /// function. 47 /// 48 /// In a theoretical system that uses tables for profiling and sjlj for 49 /// exceptions, they would be fully independent. In a normal system that uses 50 /// tables for both, the semantics are: 51 /// 52 /// nil = Needs an entry because an exception might pass by. 53 /// nounwind = No need for an entry 54 /// uwtable = Needs an entry because the ABI says so and because 55 /// an exception might pass by. 56 /// uwtable + nounwind = Needs an entry because the ABI says so. 57 58 enum AttrKind { 59 // IR-Level Attributes 60 None, ///< No attributes have been set 61 AddressSafety, ///< Address safety checking is on. 62 Alignment, ///< Alignment of parameter (5 bits) 63 ///< stored as log2 of alignment with +1 bias 64 ///< 0 means unaligned (different from align(1)) 65 AlwaysInline, ///< inline=always 66 ByVal, ///< Pass structure by value 67 InlineHint, ///< Source said inlining was desirable 68 InReg, ///< Force argument to be passed in register 69 MinSize, ///< Function must be optimized for size first 70 Naked, ///< Naked function 71 Nest, ///< Nested function static chain 72 NoAlias, ///< Considered to not alias after call 73 NoCapture, ///< Function creates no aliases of pointer 74 NoDuplicate, ///< Call cannot be duplicated 75 NoImplicitFloat, ///< Disable implicit floating point insts 76 NoInline, ///< inline=never 77 NonLazyBind, ///< Function is called early and/or 78 ///< often, so lazy binding isn't worthwhile 79 NoRedZone, ///< Disable redzone 80 NoReturn, ///< Mark the function as not returning 81 NoUnwind, ///< Function doesn't unwind stack 82 OptimizeForSize, ///< opt_size 83 ReadNone, ///< Function does not access memory 84 ReadOnly, ///< Function only reads from memory 85 ReturnsTwice, ///< Function can return twice 86 SExt, ///< Sign extended before/after call 87 StackAlignment, ///< Alignment of stack for function (3 bits) 88 ///< stored as log2 of alignment with +1 bias 0 89 ///< means unaligned (different from 90 ///< alignstack=(1)) 91 StackProtect, ///< Stack protection. 92 StackProtectReq, ///< Stack protection required. 93 StructRet, ///< Hidden pointer to structure to return 94 UWTable, ///< Function must be in a unwind table 95 ZExt, ///< Zero extended before/after call 96 97 EndAttrKinds, ///< Sentinal value useful for loops 98 99 AttrKindEmptyKey, ///< Empty key value for DenseMapInfo 100 AttrKindTombstoneKey ///< Tombstone key value for DenseMapInfo 101 }; 102private: 103 AttributeImpl *pImpl; 104 Attribute(AttributeImpl *A) : pImpl(A) {} 105public: 106 Attribute() : pImpl(0) {} 107 108 /// \brief Return a uniquified Attribute object. This takes the uniquified 109 /// value from the Builder and wraps it in the Attribute class. 110 static Attribute get(LLVMContext &Context, ArrayRef<AttrKind> Vals); 111 static Attribute get(LLVMContext &Context, AttrBuilder &B); 112 113 /// \brief Return true if the attribute is present. 114 bool hasAttribute(AttrKind Val) const; 115 116 /// \brief Return true if attributes exist 117 bool hasAttributes() const; 118 119 /// \brief Returns the alignment field of an attribute as a byte alignment 120 /// value. 121 unsigned getAlignment() const; 122 123 /// \brief Set the alignment field of an attribute. 124 void setAlignment(unsigned Align); 125 126 /// \brief Returns the stack alignment field of an attribute as a byte 127 /// alignment value. 128 unsigned getStackAlignment() const; 129 130 /// \brief Set the stack alignment field of an attribute. 131 void setStackAlignment(unsigned Align); 132 133 /// \brief Equality and non-equality query methods. 134 bool operator==(AttrKind K) const; 135 bool operator!=(AttrKind K) const; 136 137 // FIXME: Remove these 'operator' methods. 138 bool operator==(const Attribute &A) const { 139 return pImpl == A.pImpl; 140 } 141 bool operator!=(const Attribute &A) const { 142 return pImpl != A.pImpl; 143 } 144 145 uint64_t Raw() const; 146 147 /// \brief Which attributes cannot be applied to a type. 148 static Attribute typeIncompatible(Type *Ty); 149 150 /// \brief This returns an integer containing an encoding of all the LLVM 151 /// attributes found in the given attribute bitset. Any change to this 152 /// encoding is a breaking change to bitcode compatibility. 153 static uint64_t encodeLLVMAttributesForBitcode(Attribute Attrs); 154 155 /// \brief This returns an attribute bitset containing the LLVM attributes 156 /// that have been decoded from the given integer. This function must stay in 157 /// sync with 'encodeLLVMAttributesForBitcode'. 158 static Attribute decodeLLVMAttributesForBitcode(LLVMContext &C, 159 uint64_t EncodedAttrs); 160 161 /// \brief The Attribute is converted to a string of equivalent mnemonic. This 162 /// is, presumably, for writing out the mnemonics for the assembly writer. 163 std::string getAsString() const; 164}; 165 166//===----------------------------------------------------------------------===// 167/// \class 168/// \brief Provide DenseMapInfo for Attribute::AttrKinds. This is used by 169/// AttrBuilder. 170template<> struct DenseMapInfo<Attribute::AttrKind> { 171 static inline Attribute::AttrKind getEmptyKey() { 172 return Attribute::AttrKindEmptyKey; 173 } 174 static inline Attribute::AttrKind getTombstoneKey() { 175 return Attribute::AttrKindTombstoneKey; 176 } 177 static unsigned getHashValue(const Attribute::AttrKind &Val) { 178 return Val * 37U; 179 } 180 static bool isEqual(const Attribute::AttrKind &LHS, 181 const Attribute::AttrKind &RHS) { 182 return LHS == RHS; 183 } 184}; 185 186//===----------------------------------------------------------------------===// 187// AttributeSet Smart Pointer 188//===----------------------------------------------------------------------===// 189 190class AttrBuilder; 191class AttributeSetImpl; 192struct AttributeWithIndex; 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; 206 207 /// \brief The attributes that we are managing. This can be null to represent 208 /// the empty attributes list. 209 AttributeSetImpl *AttrList; 210 211 /// \brief The attributes for the specified index are returned. Attributes 212 /// for the result are denoted with Idx = 0. 213 Attribute getAttributes(unsigned Idx) const; 214 215 explicit AttributeSet(AttributeSetImpl *LI) : AttrList(LI) {} 216public: 217 AttributeSet() : AttrList(0) {} 218 AttributeSet(const AttributeSet &P) : AttrList(P.AttrList) {} 219 const AttributeSet &operator=(const AttributeSet &RHS); 220 221 //===--------------------------------------------------------------------===// 222 // Attribute List Construction and Mutation 223 //===--------------------------------------------------------------------===// 224 225 /// \brief Return an AttributeSet with the specified parameters in it. 226 static AttributeSet get(LLVMContext &C, ArrayRef<AttributeWithIndex> Attrs); 227 static AttributeSet get(LLVMContext &C, unsigned Idx, AttrBuilder &B); 228 229 /// \brief Add the specified attribute at the specified index to this 230 /// attribute list. Since attribute lists are immutable, this returns the new 231 /// list. 232 AttributeSet addAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const; 233 234 /// \brief Add attributes to the attribute set at the given index. Since 235 /// attribute sets are immutable, this returns a new set. 236 AttributeSet addAttributes(LLVMContext &C, unsigned Idx, 237 AttributeSet Attrs) const; 238 239 /// \brief Add return attributes to this attribute set. Since attribute sets 240 /// are immutable, this returns a new set. 241 AttributeSet addRetAttributes(LLVMContext &C, AttributeSet Attrs) const { 242 return addAttributes(C, ReturnIndex, Attrs); 243 } 244 245 /// \brief Add function attributes to this attribute set. Since attribute sets 246 /// are immutable, this returns a new set. 247 AttributeSet addFnAttributes(LLVMContext &C, AttributeSet Attrs) const { 248 return addAttributes(C, FunctionIndex, Attrs); 249 } 250 251 /// \brief Remove the specified attribute at the specified index from this 252 /// attribute list. Since attribute lists are immutable, this returns the new 253 /// list. 254 AttributeSet removeAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const; 255 256 //===--------------------------------------------------------------------===// 257 // Attribute List Accessors 258 //===--------------------------------------------------------------------===// 259 260 /// \brief The attributes for the specified index are returned. 261 Attribute getParamAttributes(unsigned Idx) const { 262 return getAttributes(Idx); 263 } 264 265 /// \brief The attributes for the ret value are returned. 266 AttributeSet getRetAttributes() const; 267 268 /// \brief The function attributes are returned. 269 AttributeSet getFnAttributes() const; 270 271 /// \brief Return the alignment for the specified function parameter. 272 unsigned getParamAlignment(unsigned Idx) const; 273 274 /// \brief Return true if the attribute exists at the given index. 275 bool hasAttribute(unsigned Index, Attribute::AttrKind Kind) const; 276 277 /// \brief Return true if attribute exists at the given index. 278 bool hasAttributes(unsigned Index) const; 279 280 /// \brief Get the stack alignment. 281 unsigned getStackAlignment(unsigned Index) const; 282 283 /// \brief Return the attributes at the index as a string. 284 std::string getAsString(unsigned Index) const; 285 286 uint64_t Raw(unsigned Index) const; 287 288 /// \brief Return true if the specified attribute is set for at least one 289 /// parameter or for the return value. 290 bool hasAttrSomewhere(Attribute::AttrKind Attr) const; 291 292 /// operator==/!= - Provide equality predicates. 293 bool operator==(const AttributeSet &RHS) const { 294 return AttrList == RHS.AttrList; 295 } 296 bool operator!=(const AttributeSet &RHS) const { 297 return AttrList != RHS.AttrList; 298 } 299 300 //===--------------------------------------------------------------------===// 301 // Attribute List Introspection 302 //===--------------------------------------------------------------------===// 303 304 /// \brief Return a raw pointer that uniquely identifies this attribute list. 305 void *getRawPointer() const { 306 return AttrList; 307 } 308 309 // Attributes are stored as a dense set of slots, where there is one slot for 310 // each argument that has an attribute. This allows walking over the dense 311 // set instead of walking the sparse list of attributes. 312 313 /// \brief Return true if there are no attributes. 314 bool isEmpty() const { 315 return AttrList == 0; 316 } 317 318 /// \brief Return the number of slots used in this attribute list. This is 319 /// the number of arguments that have an attribute set on them (including the 320 /// function itself). 321 unsigned getNumSlots() const; 322 323 /// \brief Return the AttributeWithIndex at the specified slot. This holds a 324 /// index number plus a set of attributes. 325 const AttributeWithIndex &getSlot(unsigned Slot) const; 326 327 void dump() const; 328}; 329 330//===----------------------------------------------------------------------===// 331/// \class 332/// \brief This is just a pair of values to associate a set of attributes with 333/// an index. 334struct AttributeWithIndex { 335 Attribute Attrs; ///< The attributes that are set, or'd together. 336 Constant *Val; ///< Value attached to attribute, e.g. alignment. 337 unsigned Index; ///< Index of the parameter for which the attributes apply. 338 ///< Index 0 is used for return value attributes. 339 ///< Index ~0U is used for function attributes. 340 341 // FIXME: These methods all need to be revised. The first one is temporary. 342 static AttributeWithIndex get(LLVMContext &C, unsigned Idx, AttributeSet AS); 343 static AttributeWithIndex get(LLVMContext &C, unsigned Idx, 344 ArrayRef<Attribute::AttrKind> Attrs) { 345 return get(Idx, Attribute::get(C, Attrs)); 346 } 347 static AttributeWithIndex get(unsigned Idx, Attribute Attrs) { 348 AttributeWithIndex P; 349 P.Index = Idx; 350 P.Attrs = Attrs; 351 P.Val = 0; 352 return P; 353 } 354 static AttributeWithIndex get(unsigned Idx, Attribute Attrs, Constant *Val) { 355 AttributeWithIndex P; 356 P.Index = Idx; 357 P.Attrs = Attrs; 358 P.Val = Val; 359 return P; 360 } 361}; 362 363//===----------------------------------------------------------------------===// 364/// \class 365/// \brief This class is used in conjunction with the Attribute::get method to 366/// create an Attribute object. The object itself is uniquified. The Builder's 367/// value, however, is not. So this can be used as a quick way to test for 368/// equality, presence of attributes, etc. 369class AttrBuilder { 370 DenseSet<Attribute::AttrKind> Attrs; 371 uint64_t Alignment; 372 uint64_t StackAlignment; 373public: 374 AttrBuilder() : Alignment(0), StackAlignment(0) {} 375 explicit AttrBuilder(uint64_t B) : Alignment(0), StackAlignment(0) { 376 addRawValue(B); 377 } 378 AttrBuilder(const Attribute &A) : Alignment(0), StackAlignment(0) { 379 addAttributes(A); 380 } 381 AttrBuilder(AttributeSet AS, unsigned Idx); 382 383 void clear(); 384 385 /// \brief Add an attribute to the builder. 386 AttrBuilder &addAttribute(Attribute::AttrKind Val); 387 388 /// \brief Remove an attribute from the builder. 389 AttrBuilder &removeAttribute(Attribute::AttrKind Val); 390 391 /// \brief Add the attributes from A to the builder. 392 AttrBuilder &addAttributes(const Attribute &A); 393 394 /// \brief Remove the attributes from A from the builder. 395 AttrBuilder &removeAttributes(const Attribute &A); 396 397 /// \brief Return true if the builder has the specified attribute. 398 bool contains(Attribute::AttrKind A) const; 399 400 /// \brief Return true if the builder has IR-level attributes. 401 bool hasAttributes() const; 402 403 /// \brief Return true if the builder has any attribute that's in the 404 /// specified attribute. 405 bool hasAttributes(const Attribute &A) const; 406 407 /// \brief Return true if the builder has an alignment attribute. 408 bool hasAlignmentAttr() const; 409 410 /// \brief Retrieve the alignment attribute, if it exists. 411 uint64_t getAlignment() const { return Alignment; } 412 413 /// \brief Retrieve the stack alignment attribute, if it exists. 414 uint64_t getStackAlignment() const { return StackAlignment; } 415 416 /// \brief This turns an int alignment (which must be a power of 2) into the 417 /// form used internally in Attribute. 418 AttrBuilder &addAlignmentAttr(unsigned Align); 419 420 /// \brief This turns an int stack alignment (which must be a power of 2) into 421 /// the form used internally in Attribute. 422 AttrBuilder &addStackAlignmentAttr(unsigned Align); 423 424 typedef DenseSet<Attribute::AttrKind>::iterator iterator; 425 typedef DenseSet<Attribute::AttrKind>::const_iterator const_iterator; 426 427 iterator begin() { return Attrs.begin(); } 428 iterator end() { return Attrs.end(); } 429 430 const_iterator begin() const { return Attrs.begin(); } 431 const_iterator end() const { return Attrs.end(); } 432 433 /// \brief Add the raw value to the internal representation. 434 /// 435 /// N.B. This should be used ONLY for decoding LLVM bitcode! 436 AttrBuilder &addRawValue(uint64_t Val); 437 438 /// \brief Remove attributes that are used on functions only. 439 void removeFunctionOnlyAttrs() { 440 removeAttribute(Attribute::NoReturn) 441 .removeAttribute(Attribute::NoUnwind) 442 .removeAttribute(Attribute::ReadNone) 443 .removeAttribute(Attribute::ReadOnly) 444 .removeAttribute(Attribute::NoInline) 445 .removeAttribute(Attribute::AlwaysInline) 446 .removeAttribute(Attribute::OptimizeForSize) 447 .removeAttribute(Attribute::StackProtect) 448 .removeAttribute(Attribute::StackProtectReq) 449 .removeAttribute(Attribute::NoRedZone) 450 .removeAttribute(Attribute::NoImplicitFloat) 451 .removeAttribute(Attribute::Naked) 452 .removeAttribute(Attribute::InlineHint) 453 .removeAttribute(Attribute::StackAlignment) 454 .removeAttribute(Attribute::UWTable) 455 .removeAttribute(Attribute::NonLazyBind) 456 .removeAttribute(Attribute::ReturnsTwice) 457 .removeAttribute(Attribute::AddressSafety) 458 .removeAttribute(Attribute::MinSize) 459 .removeAttribute(Attribute::NoDuplicate); 460 } 461 462 uint64_t Raw() const; 463 464 bool operator==(const AttrBuilder &B); 465 bool operator!=(const AttrBuilder &B) { 466 return !(*this == B); 467 } 468}; 469 470} // end llvm namespace 471 472#endif 473