Attributes.h revision 1db9b6957c2565a2322206bd5907530895f1c7ac
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_ATTRIBUTES_H 17#define LLVM_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/// \class 188/// \brief This is just a pair of values to associate a set of attributes with 189/// an index. 190struct AttributeWithIndex { 191 Attribute Attrs; ///< The attributes that are set, or'd together. 192 Constant *Val; ///< Value attached to attribute, e.g. alignment. 193 unsigned Index; ///< Index of the parameter for which the attributes apply. 194 ///< Index 0 is used for return value attributes. 195 ///< Index ~0U is used for function attributes. 196 197 static AttributeWithIndex get(LLVMContext &C, unsigned Idx, 198 ArrayRef<Attribute::AttrKind> Attrs) { 199 return get(Idx, Attribute::get(C, Attrs)); 200 } 201 static AttributeWithIndex get(unsigned Idx, Attribute Attrs) { 202 AttributeWithIndex P; 203 P.Index = Idx; 204 P.Attrs = Attrs; 205 P.Val = 0; 206 return P; 207 } 208 static AttributeWithIndex get(unsigned Idx, Attribute Attrs, Constant *Val) { 209 AttributeWithIndex P; 210 P.Index = Idx; 211 P.Attrs = Attrs; 212 P.Val = Val; 213 return P; 214 } 215}; 216 217//===----------------------------------------------------------------------===// 218// AttributeSet Smart Pointer 219//===----------------------------------------------------------------------===// 220 221class AttrBuilder; 222class AttributeSetImpl; 223 224//===----------------------------------------------------------------------===// 225/// \class 226/// \brief This class manages the ref count for the opaque AttributeSetImpl 227/// object and provides accessors for it. 228class AttributeSet { 229public: 230 enum AttrIndex { 231 ReturnIndex = 0U, 232 FunctionIndex = ~0U 233 }; 234private: 235 friend class AttrBuilder; 236 237 /// \brief The attributes that we are managing. This can be null to represent 238 /// the empty attributes list. 239 AttributeSetImpl *AttrList; 240 241 /// \brief The attributes for the specified index are returned. Attributes 242 /// for the result are denoted with Idx = 0. 243 Attribute getAttributes(unsigned Idx) const; 244 245 explicit AttributeSet(AttributeSetImpl *LI) : AttrList(LI) {} 246public: 247 AttributeSet() : AttrList(0) {} 248 AttributeSet(const AttributeSet &P) : AttrList(P.AttrList) {} 249 const AttributeSet &operator=(const AttributeSet &RHS); 250 251 //===--------------------------------------------------------------------===// 252 // Attribute List Construction and Mutation 253 //===--------------------------------------------------------------------===// 254 255 /// \brief Return an AttributeSet with the specified parameters in it. 256 static AttributeSet get(LLVMContext &C, ArrayRef<AttributeWithIndex> Attrs); 257 static AttributeSet get(LLVMContext &C, unsigned Idx, AttrBuilder &B); 258 259 /// \brief Add the specified attribute at the specified index to this 260 /// attribute list. Since attribute lists are immutable, this returns the new 261 /// list. 262 AttributeSet addAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const; 263 264 /// \brief Remove the specified attribute at the specified index from this 265 /// attribute list. Since attribute lists are immutable, this returns the new 266 /// list. 267 AttributeSet removeAttr(LLVMContext &C, unsigned Idx, Attribute Attrs) const; 268 269 //===--------------------------------------------------------------------===// 270 // Attribute List Accessors 271 //===--------------------------------------------------------------------===// 272 273 /// \brief The attributes for the specified index are returned. 274 Attribute getParamAttributes(unsigned Idx) const { 275 return getAttributes(Idx); 276 } 277 278 /// \brief The attributes for the ret value are returned. 279 Attribute getRetAttributes() const { 280 return getAttributes(ReturnIndex); 281 } 282 283 /// \brief The function attributes are returned. 284 Attribute getFnAttributes() const { 285 return getAttributes(FunctionIndex); 286 } 287 288 /// \brief Return the alignment for the specified function parameter. 289 unsigned getParamAlignment(unsigned Idx) const { 290 return getAttributes(Idx).getAlignment(); 291 } 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 attribute exists at the given index. 297 bool hasAttributes(unsigned Index) const; 298 299 /// \brief Get the stack alignment. 300 unsigned getStackAlignment(unsigned Index) const; 301 302 /// \brief Return the attributes at the index as a string. 303 std::string getAsString(unsigned Index) const; 304 305 uint64_t Raw(unsigned Index) const; 306 307 /// \brief Return true if the specified attribute is set for at least one 308 /// parameter or for the return value. 309 bool hasAttrSomewhere(Attribute::AttrKind Attr) const; 310 311 /// operator==/!= - Provide equality predicates. 312 bool operator==(const AttributeSet &RHS) const { 313 return AttrList == RHS.AttrList; 314 } 315 bool operator!=(const AttributeSet &RHS) const { 316 return AttrList != RHS.AttrList; 317 } 318 319 //===--------------------------------------------------------------------===// 320 // Attribute List Introspection 321 //===--------------------------------------------------------------------===// 322 323 /// \brief Return a raw pointer that uniquely identifies this attribute list. 324 void *getRawPointer() const { 325 return AttrList; 326 } 327 328 // Attributes are stored as a dense set of slots, where there is one slot for 329 // each argument that has an attribute. This allows walking over the dense 330 // set instead of walking the sparse list of attributes. 331 332 /// \brief Return true if there are no attributes. 333 bool isEmpty() const { 334 return AttrList == 0; 335 } 336 337 /// \brief Return the number of slots used in this attribute list. This is 338 /// the number of arguments that have an attribute set on them (including the 339 /// function itself). 340 unsigned getNumSlots() const; 341 342 /// \brief Return the AttributeWithIndex at the specified slot. This holds a 343 /// index number plus a set of attributes. 344 const AttributeWithIndex &getSlot(unsigned Slot) const; 345 346 void dump() const; 347}; 348 349//===----------------------------------------------------------------------===// 350/// \class 351/// \brief This class is used in conjunction with the Attribute::get method to 352/// create an Attribute object. The object itself is uniquified. The Builder's 353/// value, however, is not. So this can be used as a quick way to test for 354/// equality, presence of attributes, etc. 355class AttrBuilder { 356 DenseSet<Attribute::AttrKind> Attrs; 357 uint64_t Alignment; 358 uint64_t StackAlignment; 359public: 360 AttrBuilder() : Alignment(0), StackAlignment(0) {} 361 explicit AttrBuilder(uint64_t B) : Alignment(0), StackAlignment(0) { 362 addRawValue(B); 363 } 364 AttrBuilder(const Attribute &A) : Alignment(0), StackAlignment(0) { 365 addAttributes(A); 366 } 367 AttrBuilder(AttributeSet AS, unsigned Idx); 368 369 void clear(); 370 371 /// \brief Add an attribute to the builder. 372 AttrBuilder &addAttribute(Attribute::AttrKind Val); 373 374 /// \brief Remove an attribute from the builder. 375 AttrBuilder &removeAttribute(Attribute::AttrKind Val); 376 377 /// \brief Add the attributes from A to the builder. 378 AttrBuilder &addAttributes(const Attribute &A); 379 380 /// \brief Remove the attributes from A from the builder. 381 AttrBuilder &removeAttributes(const Attribute &A); 382 383 /// \brief Return true if the builder has the specified attribute. 384 bool contains(Attribute::AttrKind A) const; 385 386 /// \brief Return true if the builder has IR-level attributes. 387 bool hasAttributes() const; 388 389 /// \brief Return true if the builder has any attribute that's in the 390 /// specified attribute. 391 bool hasAttributes(const Attribute &A) const; 392 393 /// \brief Return true if the builder has an alignment attribute. 394 bool hasAlignmentAttr() const; 395 396 /// \brief Retrieve the alignment attribute, if it exists. 397 uint64_t getAlignment() const { return Alignment; } 398 399 /// \brief Retrieve the stack alignment attribute, if it exists. 400 uint64_t getStackAlignment() const { return StackAlignment; } 401 402 /// \brief This turns an int alignment (which must be a power of 2) into the 403 /// form used internally in Attribute. 404 AttrBuilder &addAlignmentAttr(unsigned Align); 405 406 /// \brief This turns an int stack alignment (which must be a power of 2) into 407 /// the form used internally in Attribute. 408 AttrBuilder &addStackAlignmentAttr(unsigned Align); 409 410 typedef DenseSet<Attribute::AttrKind>::iterator iterator; 411 typedef DenseSet<Attribute::AttrKind>::const_iterator const_iterator; 412 413 iterator begin() { return Attrs.begin(); } 414 iterator end() { return Attrs.end(); } 415 416 const_iterator begin() const { return Attrs.begin(); } 417 const_iterator end() const { return Attrs.end(); } 418 419 /// \brief Add the raw value to the internal representation. 420 /// 421 /// N.B. This should be used ONLY for decoding LLVM bitcode! 422 AttrBuilder &addRawValue(uint64_t Val); 423 424 /// \brief Remove attributes that are used on functions only. 425 void removeFunctionOnlyAttrs() { 426 removeAttribute(Attribute::NoReturn) 427 .removeAttribute(Attribute::NoUnwind) 428 .removeAttribute(Attribute::ReadNone) 429 .removeAttribute(Attribute::ReadOnly) 430 .removeAttribute(Attribute::NoInline) 431 .removeAttribute(Attribute::AlwaysInline) 432 .removeAttribute(Attribute::OptimizeForSize) 433 .removeAttribute(Attribute::StackProtect) 434 .removeAttribute(Attribute::StackProtectReq) 435 .removeAttribute(Attribute::NoRedZone) 436 .removeAttribute(Attribute::NoImplicitFloat) 437 .removeAttribute(Attribute::Naked) 438 .removeAttribute(Attribute::InlineHint) 439 .removeAttribute(Attribute::StackAlignment) 440 .removeAttribute(Attribute::UWTable) 441 .removeAttribute(Attribute::NonLazyBind) 442 .removeAttribute(Attribute::ReturnsTwice) 443 .removeAttribute(Attribute::AddressSafety) 444 .removeAttribute(Attribute::MinSize) 445 .removeAttribute(Attribute::NoDuplicate); 446 } 447 448 uint64_t Raw() const; 449 450 bool operator==(const AttrBuilder &B); 451 bool operator!=(const AttrBuilder &B) { 452 return !(*this == B); 453 } 454}; 455 456} // end llvm namespace 457 458#endif 459