1 //===--------- llvm/DataLayout.h - Data size & alignment info ---*- 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 // This file defines layout properties related to datatype size/offset/alignment 11 // information. It uses lazy annotations to cache information about how 12 // structure types are laid out and used. 13 // 14 // This structure should be created once, filled in if the defaults are not 15 // correct and then passed around by const&. None of the members functions 16 // require modification to the object. 17 // 18 //===----------------------------------------------------------------------===// 19 20 #ifndef LLVM_IR_DATALAYOUT_H 21 #define LLVM_IR_DATALAYOUT_H 22 23 #include "llvm/ADT/DenseMap.h" 24 #include "llvm/ADT/SmallVector.h" 25 #include "llvm/IR/DerivedTypes.h" 26 #include "llvm/IR/Type.h" 27 #include "llvm/Pass.h" 28 #include "llvm/Support/DataTypes.h" 29 30 // This needs to be outside of the namespace, to avoid conflict with llvm-c 31 // decl. 32 typedef struct LLVMOpaqueTargetData *LLVMTargetDataRef; 33 34 namespace llvm { 35 36 class Value; 37 class Type; 38 class IntegerType; 39 class StructType; 40 class StructLayout; 41 class Triple; 42 class GlobalVariable; 43 class LLVMContext; 44 template<typename T> 45 class ArrayRef; 46 47 /// Enum used to categorize the alignment types stored by LayoutAlignElem 48 enum AlignTypeEnum { 49 INVALID_ALIGN = 0, 50 INTEGER_ALIGN = 'i', 51 VECTOR_ALIGN = 'v', 52 FLOAT_ALIGN = 'f', 53 AGGREGATE_ALIGN = 'a' 54 }; 55 56 // FIXME: Currently the DataLayout string carries a "preferred alignment" 57 // for types. As the DataLayout is module/global, this should likely be 58 // sunk down to an FTTI element that is queried rather than a global 59 // preference. 60 61 /// \brief Layout alignment element. 62 /// 63 /// Stores the alignment data associated with a given alignment type (integer, 64 /// vector, float) and type bit width. 65 /// 66 /// \note The unusual order of elements in the structure attempts to reduce 67 /// padding and make the structure slightly more cache friendly. 68 struct LayoutAlignElem { 69 /// \brief Alignment type from \c AlignTypeEnum 70 unsigned AlignType : 8; 71 unsigned TypeBitWidth : 24; 72 unsigned ABIAlign : 16; 73 unsigned PrefAlign : 16; 74 75 static LayoutAlignElem get(AlignTypeEnum align_type, unsigned abi_align, 76 unsigned pref_align, uint32_t bit_width); 77 bool operator==(const LayoutAlignElem &rhs) const; 78 }; 79 80 /// \brief Layout pointer alignment element. 81 /// 82 /// Stores the alignment data associated with a given pointer and address space. 83 /// 84 /// \note The unusual order of elements in the structure attempts to reduce 85 /// padding and make the structure slightly more cache friendly. 86 struct PointerAlignElem { 87 unsigned ABIAlign; 88 unsigned PrefAlign; 89 uint32_t TypeByteWidth; 90 uint32_t AddressSpace; 91 92 /// Initializer 93 static PointerAlignElem get(uint32_t AddressSpace, unsigned ABIAlign, 94 unsigned PrefAlign, uint32_t TypeByteWidth); 95 bool operator==(const PointerAlignElem &rhs) const; 96 }; 97 98 /// \brief A parsed version of the target data layout string in and methods for 99 /// querying it. 100 /// 101 /// The target data layout string is specified *by the target* - a frontend 102 /// generating LLVM IR is required to generate the right target data for the 103 /// target being codegen'd to. 104 class DataLayout { 105 private: 106 /// Defaults to false. 107 bool BigEndian; 108 109 unsigned StackNaturalAlign; 110 111 enum ManglingModeT { 112 MM_None, 113 MM_ELF, 114 MM_MachO, 115 MM_WinCOFF, 116 MM_WinCOFFX86, 117 MM_Mips 118 }; 119 ManglingModeT ManglingMode; 120 121 SmallVector<unsigned char, 8> LegalIntWidths; 122 123 /// \brief Primitive type alignment data. 124 SmallVector<LayoutAlignElem, 16> Alignments; 125 126 /// \brief The string representation used to create this DataLayout 127 std::string StringRepresentation; 128 129 typedef SmallVector<PointerAlignElem, 8> PointersTy; 130 PointersTy Pointers; 131 132 PointersTy::const_iterator 133 findPointerLowerBound(uint32_t AddressSpace) const { 134 return const_cast<DataLayout *>(this)->findPointerLowerBound(AddressSpace); 135 } 136 137 PointersTy::iterator findPointerLowerBound(uint32_t AddressSpace); 138 139 /// This member is a signal that a requested alignment type and bit width were 140 /// not found in the SmallVector. 141 static const LayoutAlignElem InvalidAlignmentElem; 142 143 /// This member is a signal that a requested pointer type and bit width were 144 /// not found in the DenseSet. 145 static const PointerAlignElem InvalidPointerElem; 146 147 // The StructType -> StructLayout map. 148 mutable void *LayoutMap; 149 150 void setAlignment(AlignTypeEnum align_type, unsigned abi_align, 151 unsigned pref_align, uint32_t bit_width); 152 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width, 153 bool ABIAlign, Type *Ty) const; 154 void setPointerAlignment(uint32_t AddrSpace, unsigned ABIAlign, 155 unsigned PrefAlign, uint32_t TypeByteWidth); 156 157 /// Internal helper method that returns requested alignment for type. 158 unsigned getAlignment(Type *Ty, bool abi_or_pref) const; 159 160 /// \brief Valid alignment predicate. 161 /// 162 /// Predicate that tests a LayoutAlignElem reference returned by get() against 163 /// InvalidAlignmentElem. 164 bool validAlignment(const LayoutAlignElem &align) const { 165 return &align != &InvalidAlignmentElem; 166 } 167 168 /// \brief Valid pointer predicate. 169 /// 170 /// Predicate that tests a PointerAlignElem reference returned by get() 171 /// against \c InvalidPointerElem. 172 bool validPointer(const PointerAlignElem &align) const { 173 return &align != &InvalidPointerElem; 174 } 175 176 /// Parses a target data specification string. Assert if the string is 177 /// malformed. 178 void parseSpecifier(StringRef LayoutDescription); 179 180 // Free all internal data structures. 181 void clear(); 182 183 public: 184 /// Constructs a DataLayout from a specification string. See reset(). 185 explicit DataLayout(StringRef LayoutDescription) : LayoutMap(nullptr) { 186 reset(LayoutDescription); 187 } 188 189 /// Initialize target data from properties stored in the module. 190 explicit DataLayout(const Module *M); 191 192 void init(const Module *M); 193 194 DataLayout(const DataLayout &DL) : LayoutMap(nullptr) { *this = DL; } 195 196 DataLayout &operator=(const DataLayout &DL) { 197 clear(); 198 StringRepresentation = DL.StringRepresentation; 199 BigEndian = DL.isBigEndian(); 200 StackNaturalAlign = DL.StackNaturalAlign; 201 ManglingMode = DL.ManglingMode; 202 LegalIntWidths = DL.LegalIntWidths; 203 Alignments = DL.Alignments; 204 Pointers = DL.Pointers; 205 return *this; 206 } 207 208 bool operator==(const DataLayout &Other) const; 209 bool operator!=(const DataLayout &Other) const { return !(*this == Other); } 210 211 ~DataLayout(); // Not virtual, do not subclass this class 212 213 /// Parse a data layout string (with fallback to default values). 214 void reset(StringRef LayoutDescription); 215 216 /// Layout endianness... 217 bool isLittleEndian() const { return !BigEndian; } 218 bool isBigEndian() const { return BigEndian; } 219 220 /// \brief Returns the string representation of the DataLayout. 221 /// 222 /// This representation is in the same format accepted by the string 223 /// constructor above. This should not be used to compare two DataLayout as 224 /// different string can represent the same layout. 225 const std::string &getStringRepresentation() const { 226 return StringRepresentation; 227 } 228 229 /// \brief Test if the DataLayout was constructed from an empty string. 230 bool isDefault() const { return StringRepresentation.empty(); } 231 232 /// \brief Returns true if the specified type is known to be a native integer 233 /// type supported by the CPU. 234 /// 235 /// For example, i64 is not native on most 32-bit CPUs and i37 is not native 236 /// on any known one. This returns false if the integer width is not legal. 237 /// 238 /// The width is specified in bits. 239 bool isLegalInteger(unsigned Width) const { 240 for (unsigned LegalIntWidth : LegalIntWidths) 241 if (LegalIntWidth == Width) 242 return true; 243 return false; 244 } 245 246 bool isIllegalInteger(unsigned Width) const { return !isLegalInteger(Width); } 247 248 /// Returns true if the given alignment exceeds the natural stack alignment. 249 bool exceedsNaturalStackAlignment(unsigned Align) const { 250 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign); 251 } 252 253 unsigned getStackAlignment() const { return StackNaturalAlign; } 254 255 bool hasMicrosoftFastStdCallMangling() const { 256 return ManglingMode == MM_WinCOFFX86; 257 } 258 259 bool hasLinkerPrivateGlobalPrefix() const { return ManglingMode == MM_MachO; } 260 261 const char *getLinkerPrivateGlobalPrefix() const { 262 if (ManglingMode == MM_MachO) 263 return "l"; 264 return ""; 265 } 266 267 char getGlobalPrefix() const { 268 switch (ManglingMode) { 269 case MM_None: 270 case MM_ELF: 271 case MM_Mips: 272 case MM_WinCOFF: 273 return '\0'; 274 case MM_MachO: 275 case MM_WinCOFFX86: 276 return '_'; 277 } 278 llvm_unreachable("invalid mangling mode"); 279 } 280 281 const char *getPrivateGlobalPrefix() const { 282 switch (ManglingMode) { 283 case MM_None: 284 return ""; 285 case MM_ELF: 286 return ".L"; 287 case MM_Mips: 288 return "$"; 289 case MM_MachO: 290 case MM_WinCOFF: 291 case MM_WinCOFFX86: 292 return "L"; 293 } 294 llvm_unreachable("invalid mangling mode"); 295 } 296 297 static const char *getManglingComponent(const Triple &T); 298 299 /// \brief Returns true if the specified type fits in a native integer type 300 /// supported by the CPU. 301 /// 302 /// For example, if the CPU only supports i32 as a native integer type, then 303 /// i27 fits in a legal integer type but i45 does not. 304 bool fitsInLegalInteger(unsigned Width) const { 305 for (unsigned LegalIntWidth : LegalIntWidths) 306 if (Width <= LegalIntWidth) 307 return true; 308 return false; 309 } 310 311 /// Layout pointer alignment 312 /// FIXME: The defaults need to be removed once all of 313 /// the backends/clients are updated. 314 unsigned getPointerABIAlignment(unsigned AS = 0) const; 315 316 /// Return target's alignment for stack-based pointers 317 /// FIXME: The defaults need to be removed once all of 318 /// the backends/clients are updated. 319 unsigned getPointerPrefAlignment(unsigned AS = 0) const; 320 321 /// Layout pointer size 322 /// FIXME: The defaults need to be removed once all of 323 /// the backends/clients are updated. 324 unsigned getPointerSize(unsigned AS = 0) const; 325 326 /// Layout pointer size, in bits 327 /// FIXME: The defaults need to be removed once all of 328 /// the backends/clients are updated. 329 unsigned getPointerSizeInBits(unsigned AS = 0) const { 330 return getPointerSize(AS) * 8; 331 } 332 333 /// Layout pointer size, in bits, based on the type. If this function is 334 /// called with a pointer type, then the type size of the pointer is returned. 335 /// If this function is called with a vector of pointers, then the type size 336 /// of the pointer is returned. This should only be called with a pointer or 337 /// vector of pointers. 338 unsigned getPointerTypeSizeInBits(Type *) const; 339 340 unsigned getPointerTypeSize(Type *Ty) const { 341 return getPointerTypeSizeInBits(Ty) / 8; 342 } 343 344 /// Size examples: 345 /// 346 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*] 347 /// ---- ---------- --------------- --------------- 348 /// i1 1 8 8 349 /// i8 8 8 8 350 /// i19 19 24 32 351 /// i32 32 32 32 352 /// i100 100 104 128 353 /// i128 128 128 128 354 /// Float 32 32 32 355 /// Double 64 64 64 356 /// X86_FP80 80 80 96 357 /// 358 /// [*] The alloc size depends on the alignment, and thus on the target. 359 /// These values are for x86-32 linux. 360 361 /// \brief Returns the number of bits necessary to hold the specified type. 362 /// 363 /// For example, returns 36 for i36 and 80 for x86_fp80. The type passed must 364 /// have a size (Type::isSized() must return true). 365 uint64_t getTypeSizeInBits(Type *Ty) const; 366 367 /// \brief Returns the maximum number of bytes that may be overwritten by 368 /// storing the specified type. 369 /// 370 /// For example, returns 5 for i36 and 10 for x86_fp80. 371 uint64_t getTypeStoreSize(Type *Ty) const { 372 return (getTypeSizeInBits(Ty) + 7) / 8; 373 } 374 375 /// \brief Returns the maximum number of bits that may be overwritten by 376 /// storing the specified type; always a multiple of 8. 377 /// 378 /// For example, returns 40 for i36 and 80 for x86_fp80. 379 uint64_t getTypeStoreSizeInBits(Type *Ty) const { 380 return 8 * getTypeStoreSize(Ty); 381 } 382 383 /// \brief Returns the offset in bytes between successive objects of the 384 /// specified type, including alignment padding. 385 /// 386 /// This is the amount that alloca reserves for this type. For example, 387 /// returns 12 or 16 for x86_fp80, depending on alignment. 388 uint64_t getTypeAllocSize(Type *Ty) const { 389 // Round up to the next alignment boundary. 390 return RoundUpToAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty)); 391 } 392 393 /// \brief Returns the offset in bits between successive objects of the 394 /// specified type, including alignment padding; always a multiple of 8. 395 /// 396 /// This is the amount that alloca reserves for this type. For example, 397 /// returns 96 or 128 for x86_fp80, depending on alignment. 398 uint64_t getTypeAllocSizeInBits(Type *Ty) const { 399 return 8 * getTypeAllocSize(Ty); 400 } 401 402 /// \brief Returns the minimum ABI-required alignment for the specified type. 403 unsigned getABITypeAlignment(Type *Ty) const; 404 405 /// \brief Returns the minimum ABI-required alignment for an integer type of 406 /// the specified bitwidth. 407 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const; 408 409 /// \brief Returns the preferred stack/global alignment for the specified 410 /// type. 411 /// 412 /// This is always at least as good as the ABI alignment. 413 unsigned getPrefTypeAlignment(Type *Ty) const; 414 415 /// \brief Returns the preferred alignment for the specified type, returned as 416 /// log2 of the value (a shift amount). 417 unsigned getPreferredTypeAlignmentShift(Type *Ty) const; 418 419 /// \brief Returns an integer type with size at least as big as that of a 420 /// pointer in the given address space. 421 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const; 422 423 /// \brief Returns an integer (vector of integer) type with size at least as 424 /// big as that of a pointer of the given pointer (vector of pointer) type. 425 Type *getIntPtrType(Type *) const; 426 427 /// \brief Returns the smallest integer type with size at least as big as 428 /// Width bits. 429 Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const; 430 431 /// \brief Returns the largest legal integer type, or null if none are set. 432 Type *getLargestLegalIntType(LLVMContext &C) const { 433 unsigned LargestSize = getLargestLegalIntTypeSize(); 434 return (LargestSize == 0) ? nullptr : Type::getIntNTy(C, LargestSize); 435 } 436 437 /// \brief Returns the size of largest legal integer type size, or 0 if none 438 /// are set. 439 unsigned getLargestLegalIntTypeSize() const; 440 441 /// \brief Returns the offset from the beginning of the type for the specified 442 /// indices. 443 /// 444 /// This is used to implement getelementptr. 445 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const; 446 447 /// \brief Returns a StructLayout object, indicating the alignment of the 448 /// struct, its size, and the offsets of its fields. 449 /// 450 /// Note that this information is lazily cached. 451 const StructLayout *getStructLayout(StructType *Ty) const; 452 453 /// \brief Returns the preferred alignment of the specified global. 454 /// 455 /// This includes an explicitly requested alignment (if the global has one). 456 unsigned getPreferredAlignment(const GlobalVariable *GV) const; 457 458 /// \brief Returns the preferred alignment of the specified global, returned 459 /// in log form. 460 /// 461 /// This includes an explicitly requested alignment (if the global has one). 462 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const; 463 }; 464 465 inline DataLayout *unwrap(LLVMTargetDataRef P) { 466 return reinterpret_cast<DataLayout *>(P); 467 } 468 469 inline LLVMTargetDataRef wrap(const DataLayout *P) { 470 return reinterpret_cast<LLVMTargetDataRef>(const_cast<DataLayout *>(P)); 471 } 472 473 /// Used to lazily calculate structure layout information for a target machine, 474 /// based on the DataLayout structure. 475 class StructLayout { 476 uint64_t StructSize; 477 unsigned StructAlignment; 478 bool IsPadded : 1; 479 unsigned NumElements : 31; 480 uint64_t MemberOffsets[1]; // variable sized array! 481 public: 482 uint64_t getSizeInBytes() const { return StructSize; } 483 484 uint64_t getSizeInBits() const { return 8 * StructSize; } 485 486 unsigned getAlignment() const { return StructAlignment; } 487 488 /// Returns whether the struct has padding or not between its fields. 489 /// NB: Padding in nested element is not taken into account. 490 bool hasPadding() const { return IsPadded; } 491 492 /// \brief Given a valid byte offset into the structure, returns the structure 493 /// index that contains it. 494 unsigned getElementContainingOffset(uint64_t Offset) const; 495 496 uint64_t getElementOffset(unsigned Idx) const { 497 assert(Idx < NumElements && "Invalid element idx!"); 498 return MemberOffsets[Idx]; 499 } 500 501 uint64_t getElementOffsetInBits(unsigned Idx) const { 502 return getElementOffset(Idx) * 8; 503 } 504 505 private: 506 friend class DataLayout; // Only DataLayout can create this class 507 StructLayout(StructType *ST, const DataLayout &DL); 508 }; 509 510 // The implementation of this method is provided inline as it is particularly 511 // well suited to constant folding when called on a specific Type subclass. 512 inline uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const { 513 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!"); 514 switch (Ty->getTypeID()) { 515 case Type::LabelTyID: 516 return getPointerSizeInBits(0); 517 case Type::PointerTyID: 518 return getPointerSizeInBits(Ty->getPointerAddressSpace()); 519 case Type::ArrayTyID: { 520 ArrayType *ATy = cast<ArrayType>(Ty); 521 return ATy->getNumElements() * 522 getTypeAllocSizeInBits(ATy->getElementType()); 523 } 524 case Type::StructTyID: 525 // Get the layout annotation... which is lazily created on demand. 526 return getStructLayout(cast<StructType>(Ty))->getSizeInBits(); 527 case Type::IntegerTyID: 528 return Ty->getIntegerBitWidth(); 529 case Type::HalfTyID: 530 return 16; 531 case Type::FloatTyID: 532 return 32; 533 case Type::DoubleTyID: 534 case Type::X86_MMXTyID: 535 return 64; 536 case Type::PPC_FP128TyID: 537 case Type::FP128TyID: 538 return 128; 539 // In memory objects this is always aligned to a higher boundary, but 540 // only 80 bits contain information. 541 case Type::X86_FP80TyID: 542 return 80; 543 case Type::VectorTyID: { 544 VectorType *VTy = cast<VectorType>(Ty); 545 return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType()); 546 } 547 default: 548 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type"); 549 } 550 } 551 552 } // End llvm namespace 553 554 #endif 555
