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/ArrayRef.h" 24 #include "llvm/ADT/STLExtras.h" 25 #include "llvm/ADT/SmallVector.h" 26 #include "llvm/ADT/StringRef.h" 27 #include "llvm/IR/DerivedTypes.h" 28 #include "llvm/IR/Type.h" 29 #include "llvm/Pass.h" 30 #include "llvm/Support/Casting.h" 31 #include "llvm/Support/ErrorHandling.h" 32 #include "llvm/Support/MathExtras.h" 33 #include <cassert> 34 #include <cstdint> 35 #include <string> 36 37 // This needs to be outside of the namespace, to avoid conflict with llvm-c 38 // decl. 39 using LLVMTargetDataRef = struct LLVMOpaqueTargetData *; 40 41 namespace llvm { 42 43 class GlobalVariable; 44 class LLVMContext; 45 class Module; 46 class StructLayout; 47 class Triple; 48 class Value; 49 50 /// Enum used to categorize the alignment types stored by LayoutAlignElem 51 enum AlignTypeEnum { 52 INVALID_ALIGN = 0, 53 INTEGER_ALIGN = 'i', 54 VECTOR_ALIGN = 'v', 55 FLOAT_ALIGN = 'f', 56 AGGREGATE_ALIGN = 'a' 57 }; 58 59 // FIXME: Currently the DataLayout string carries a "preferred alignment" 60 // for types. As the DataLayout is module/global, this should likely be 61 // sunk down to an FTTI element that is queried rather than a global 62 // preference. 63 64 /// \brief Layout alignment element. 65 /// 66 /// Stores the alignment data associated with a given alignment type (integer, 67 /// vector, float) and type bit width. 68 /// 69 /// \note The unusual order of elements in the structure attempts to reduce 70 /// padding and make the structure slightly more cache friendly. 71 struct LayoutAlignElem { 72 /// \brief Alignment type from \c AlignTypeEnum 73 unsigned AlignType : 8; 74 unsigned TypeBitWidth : 24; 75 unsigned ABIAlign : 16; 76 unsigned PrefAlign : 16; 77 78 static LayoutAlignElem get(AlignTypeEnum align_type, unsigned abi_align, 79 unsigned pref_align, uint32_t bit_width); 80 81 bool operator==(const LayoutAlignElem &rhs) const; 82 }; 83 84 /// \brief Layout pointer alignment element. 85 /// 86 /// Stores the alignment data associated with a given pointer and address space. 87 /// 88 /// \note The unusual order of elements in the structure attempts to reduce 89 /// padding and make the structure slightly more cache friendly. 90 struct PointerAlignElem { 91 unsigned ABIAlign; 92 unsigned PrefAlign; 93 uint32_t TypeByteWidth; 94 uint32_t AddressSpace; 95 96 /// Initializer 97 static PointerAlignElem get(uint32_t AddressSpace, unsigned ABIAlign, 98 unsigned PrefAlign, uint32_t TypeByteWidth); 99 100 bool operator==(const PointerAlignElem &rhs) const; 101 }; 102 103 /// \brief A parsed version of the target data layout string in and methods for 104 /// querying it. 105 /// 106 /// The target data layout string is specified *by the target* - a frontend 107 /// generating LLVM IR is required to generate the right target data for the 108 /// target being codegen'd to. 109 class DataLayout { 110 private: 111 /// Defaults to false. 112 bool BigEndian; 113 114 unsigned AllocaAddrSpace; 115 unsigned StackNaturalAlign; 116 117 enum ManglingModeT { 118 MM_None, 119 MM_ELF, 120 MM_MachO, 121 MM_WinCOFF, 122 MM_WinCOFFX86, 123 MM_Mips 124 }; 125 ManglingModeT ManglingMode; 126 127 SmallVector<unsigned char, 8> LegalIntWidths; 128 129 /// \brief Primitive type alignment data. This is sorted by type and bit 130 /// width during construction. 131 using AlignmentsTy = SmallVector<LayoutAlignElem, 16>; 132 AlignmentsTy Alignments; 133 134 AlignmentsTy::const_iterator 135 findAlignmentLowerBound(AlignTypeEnum AlignType, uint32_t BitWidth) const { 136 return const_cast<DataLayout *>(this)->findAlignmentLowerBound(AlignType, 137 BitWidth); 138 } 139 140 AlignmentsTy::iterator 141 findAlignmentLowerBound(AlignTypeEnum AlignType, uint32_t BitWidth); 142 143 /// \brief The string representation used to create this DataLayout 144 std::string StringRepresentation; 145 146 using PointersTy = SmallVector<PointerAlignElem, 8>; 147 PointersTy Pointers; 148 149 PointersTy::const_iterator 150 findPointerLowerBound(uint32_t AddressSpace) const { 151 return const_cast<DataLayout *>(this)->findPointerLowerBound(AddressSpace); 152 } 153 154 PointersTy::iterator findPointerLowerBound(uint32_t AddressSpace); 155 156 // The StructType -> StructLayout map. 157 mutable void *LayoutMap = nullptr; 158 159 /// Pointers in these address spaces are non-integral, and don't have a 160 /// well-defined bitwise representation. 161 SmallVector<unsigned, 8> NonIntegralAddressSpaces; 162 163 void setAlignment(AlignTypeEnum align_type, unsigned abi_align, 164 unsigned pref_align, uint32_t bit_width); 165 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width, 166 bool ABIAlign, Type *Ty) const; 167 void setPointerAlignment(uint32_t AddrSpace, unsigned ABIAlign, 168 unsigned PrefAlign, uint32_t TypeByteWidth); 169 170 /// Internal helper method that returns requested alignment for type. 171 unsigned getAlignment(Type *Ty, bool abi_or_pref) const; 172 173 /// Parses a target data specification string. Assert if the string is 174 /// malformed. 175 void parseSpecifier(StringRef LayoutDescription); 176 177 // Free all internal data structures. 178 void clear(); 179 180 public: 181 /// Constructs a DataLayout from a specification string. See reset(). 182 explicit DataLayout(StringRef LayoutDescription) { 183 reset(LayoutDescription); 184 } 185 186 /// Initialize target data from properties stored in the module. 187 explicit DataLayout(const Module *M); 188 189 DataLayout(const DataLayout &DL) { *this = DL; } 190 191 ~DataLayout(); // Not virtual, do not subclass this class 192 193 DataLayout &operator=(const DataLayout &DL) { 194 clear(); 195 StringRepresentation = DL.StringRepresentation; 196 BigEndian = DL.isBigEndian(); 197 AllocaAddrSpace = DL.AllocaAddrSpace; 198 StackNaturalAlign = DL.StackNaturalAlign; 199 ManglingMode = DL.ManglingMode; 200 LegalIntWidths = DL.LegalIntWidths; 201 Alignments = DL.Alignments; 202 Pointers = DL.Pointers; 203 NonIntegralAddressSpaces = DL.NonIntegralAddressSpaces; 204 return *this; 205 } 206 207 bool operator==(const DataLayout &Other) const; 208 bool operator!=(const DataLayout &Other) const { return !(*this == Other); } 209 210 void init(const Module *M); 211 212 /// Parse a data layout string (with fallback to default values). 213 void reset(StringRef LayoutDescription); 214 215 /// Layout endianness... 216 bool isLittleEndian() const { return !BigEndian; } 217 bool isBigEndian() const { return BigEndian; } 218 219 /// \brief Returns the string representation of the DataLayout. 220 /// 221 /// This representation is in the same format accepted by the string 222 /// constructor above. This should not be used to compare two DataLayout as 223 /// different string can represent the same layout. 224 const std::string &getStringRepresentation() const { 225 return StringRepresentation; 226 } 227 228 /// \brief Test if the DataLayout was constructed from an empty string. 229 bool isDefault() const { return StringRepresentation.empty(); } 230 231 /// \brief Returns true if the specified type is known to be a native integer 232 /// type supported by the CPU. 233 /// 234 /// For example, i64 is not native on most 32-bit CPUs and i37 is not native 235 /// on any known one. This returns false if the integer width is not legal. 236 /// 237 /// The width is specified in bits. 238 bool isLegalInteger(uint64_t Width) const { 239 for (unsigned LegalIntWidth : LegalIntWidths) 240 if (LegalIntWidth == Width) 241 return true; 242 return false; 243 } 244 245 bool isIllegalInteger(uint64_t Width) const { return !isLegalInteger(Width); } 246 247 /// Returns true if the given alignment exceeds the natural stack alignment. 248 bool exceedsNaturalStackAlignment(unsigned Align) const { 249 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign); 250 } 251 252 unsigned getStackAlignment() const { return StackNaturalAlign; } 253 unsigned getAllocaAddrSpace() const { return AllocaAddrSpace; } 254 255 bool hasMicrosoftFastStdCallMangling() const { 256 return ManglingMode == MM_WinCOFFX86; 257 } 258 259 bool hasLinkerPrivateGlobalPrefix() const { return ManglingMode == MM_MachO; } 260 261 StringRef 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 StringRef getPrivateGlobalPrefix() const { 282 switch (ManglingMode) { 283 case MM_None: 284 return ""; 285 case MM_ELF: 286 case MM_WinCOFF: 287 return ".L"; 288 case MM_Mips: 289 return "$"; 290 case MM_MachO: 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 /// Return the address spaces containing non-integral pointers. Pointers in 327 /// this address space don't have a well-defined bitwise representation. 328 ArrayRef<unsigned> getNonIntegralAddressSpaces() const { 329 return NonIntegralAddressSpaces; 330 } 331 332 bool isNonIntegralPointerType(PointerType *PT) const { 333 ArrayRef<unsigned> NonIntegralSpaces = getNonIntegralAddressSpaces(); 334 return find(NonIntegralSpaces, PT->getAddressSpace()) != 335 NonIntegralSpaces.end(); 336 } 337 338 bool isNonIntegralPointerType(Type *Ty) const { 339 auto *PTy = dyn_cast<PointerType>(Ty); 340 return PTy && isNonIntegralPointerType(PTy); 341 } 342 343 /// Layout pointer size, in bits 344 /// FIXME: The defaults need to be removed once all of 345 /// the backends/clients are updated. 346 unsigned getPointerSizeInBits(unsigned AS = 0) const { 347 return getPointerSize(AS) * 8; 348 } 349 350 /// Layout pointer size, in bits, based on the type. If this function is 351 /// called with a pointer type, then the type size of the pointer is returned. 352 /// If this function is called with a vector of pointers, then the type size 353 /// of the pointer is returned. This should only be called with a pointer or 354 /// vector of pointers. 355 unsigned getPointerTypeSizeInBits(Type *) const; 356 357 unsigned getPointerTypeSize(Type *Ty) const { 358 return getPointerTypeSizeInBits(Ty) / 8; 359 } 360 361 /// Size examples: 362 /// 363 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*] 364 /// ---- ---------- --------------- --------------- 365 /// i1 1 8 8 366 /// i8 8 8 8 367 /// i19 19 24 32 368 /// i32 32 32 32 369 /// i100 100 104 128 370 /// i128 128 128 128 371 /// Float 32 32 32 372 /// Double 64 64 64 373 /// X86_FP80 80 80 96 374 /// 375 /// [*] The alloc size depends on the alignment, and thus on the target. 376 /// These values are for x86-32 linux. 377 378 /// \brief Returns the number of bits necessary to hold the specified type. 379 /// 380 /// For example, returns 36 for i36 and 80 for x86_fp80. The type passed must 381 /// have a size (Type::isSized() must return true). 382 uint64_t getTypeSizeInBits(Type *Ty) const; 383 384 /// \brief Returns the maximum number of bytes that may be overwritten by 385 /// storing the specified type. 386 /// 387 /// For example, returns 5 for i36 and 10 for x86_fp80. 388 uint64_t getTypeStoreSize(Type *Ty) const { 389 return (getTypeSizeInBits(Ty) + 7) / 8; 390 } 391 392 /// \brief Returns the maximum number of bits that may be overwritten by 393 /// storing the specified type; always a multiple of 8. 394 /// 395 /// For example, returns 40 for i36 and 80 for x86_fp80. 396 uint64_t getTypeStoreSizeInBits(Type *Ty) const { 397 return 8 * getTypeStoreSize(Ty); 398 } 399 400 /// \brief Returns the offset in bytes between successive objects of the 401 /// specified type, including alignment padding. 402 /// 403 /// This is the amount that alloca reserves for this type. For example, 404 /// returns 12 or 16 for x86_fp80, depending on alignment. 405 uint64_t getTypeAllocSize(Type *Ty) const { 406 // Round up to the next alignment boundary. 407 return alignTo(getTypeStoreSize(Ty), getABITypeAlignment(Ty)); 408 } 409 410 /// \brief Returns the offset in bits between successive objects of the 411 /// specified type, including alignment padding; always a multiple of 8. 412 /// 413 /// This is the amount that alloca reserves for this type. For example, 414 /// returns 96 or 128 for x86_fp80, depending on alignment. 415 uint64_t getTypeAllocSizeInBits(Type *Ty) const { 416 return 8 * getTypeAllocSize(Ty); 417 } 418 419 /// \brief Returns the minimum ABI-required alignment for the specified type. 420 unsigned getABITypeAlignment(Type *Ty) const; 421 422 /// \brief Returns the minimum ABI-required alignment for an integer type of 423 /// the specified bitwidth. 424 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const; 425 426 /// \brief Returns the preferred stack/global alignment for the specified 427 /// type. 428 /// 429 /// This is always at least as good as the ABI alignment. 430 unsigned getPrefTypeAlignment(Type *Ty) const; 431 432 /// \brief Returns the preferred alignment for the specified type, returned as 433 /// log2 of the value (a shift amount). 434 unsigned getPreferredTypeAlignmentShift(Type *Ty) const; 435 436 /// \brief Returns an integer type with size at least as big as that of a 437 /// pointer in the given address space. 438 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const; 439 440 /// \brief Returns an integer (vector of integer) type with size at least as 441 /// big as that of a pointer of the given pointer (vector of pointer) type. 442 Type *getIntPtrType(Type *) const; 443 444 /// \brief Returns the smallest integer type with size at least as big as 445 /// Width bits. 446 Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const; 447 448 /// \brief Returns the largest legal integer type, or null if none are set. 449 Type *getLargestLegalIntType(LLVMContext &C) const { 450 unsigned LargestSize = getLargestLegalIntTypeSizeInBits(); 451 return (LargestSize == 0) ? nullptr : Type::getIntNTy(C, LargestSize); 452 } 453 454 /// \brief Returns the size of largest legal integer type size, or 0 if none 455 /// are set. 456 unsigned getLargestLegalIntTypeSizeInBits() const; 457 458 /// \brief Returns the offset from the beginning of the type for the specified 459 /// indices. 460 /// 461 /// Note that this takes the element type, not the pointer type. 462 /// This is used to implement getelementptr. 463 int64_t getIndexedOffsetInType(Type *ElemTy, ArrayRef<Value *> Indices) const; 464 465 /// \brief Returns a StructLayout object, indicating the alignment of the 466 /// struct, its size, and the offsets of its fields. 467 /// 468 /// Note that this information is lazily cached. 469 const StructLayout *getStructLayout(StructType *Ty) const; 470 471 /// \brief Returns the preferred alignment of the specified global. 472 /// 473 /// This includes an explicitly requested alignment (if the global has one). 474 unsigned getPreferredAlignment(const GlobalVariable *GV) const; 475 476 /// \brief Returns the preferred alignment of the specified global, returned 477 /// in log form. 478 /// 479 /// This includes an explicitly requested alignment (if the global has one). 480 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const; 481 }; 482 483 inline DataLayout *unwrap(LLVMTargetDataRef P) { 484 return reinterpret_cast<DataLayout *>(P); 485 } 486 487 inline LLVMTargetDataRef wrap(const DataLayout *P) { 488 return reinterpret_cast<LLVMTargetDataRef>(const_cast<DataLayout *>(P)); 489 } 490 491 /// Used to lazily calculate structure layout information for a target machine, 492 /// based on the DataLayout structure. 493 class StructLayout { 494 uint64_t StructSize; 495 unsigned StructAlignment; 496 unsigned IsPadded : 1; 497 unsigned NumElements : 31; 498 uint64_t MemberOffsets[1]; // variable sized array! 499 500 public: 501 uint64_t getSizeInBytes() const { return StructSize; } 502 503 uint64_t getSizeInBits() const { return 8 * StructSize; } 504 505 unsigned getAlignment() const { return StructAlignment; } 506 507 /// Returns whether the struct has padding or not between its fields. 508 /// NB: Padding in nested element is not taken into account. 509 bool hasPadding() const { return IsPadded; } 510 511 /// \brief Given a valid byte offset into the structure, returns the structure 512 /// index that contains it. 513 unsigned getElementContainingOffset(uint64_t Offset) const; 514 515 uint64_t getElementOffset(unsigned Idx) const { 516 assert(Idx < NumElements && "Invalid element idx!"); 517 return MemberOffsets[Idx]; 518 } 519 520 uint64_t getElementOffsetInBits(unsigned Idx) const { 521 return getElementOffset(Idx) * 8; 522 } 523 524 private: 525 friend class DataLayout; // Only DataLayout can create this class 526 527 StructLayout(StructType *ST, const DataLayout &DL); 528 }; 529 530 // The implementation of this method is provided inline as it is particularly 531 // well suited to constant folding when called on a specific Type subclass. 532 inline uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const { 533 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!"); 534 switch (Ty->getTypeID()) { 535 case Type::LabelTyID: 536 return getPointerSizeInBits(0); 537 case Type::PointerTyID: 538 return getPointerSizeInBits(Ty->getPointerAddressSpace()); 539 case Type::ArrayTyID: { 540 ArrayType *ATy = cast<ArrayType>(Ty); 541 return ATy->getNumElements() * 542 getTypeAllocSizeInBits(ATy->getElementType()); 543 } 544 case Type::StructTyID: 545 // Get the layout annotation... which is lazily created on demand. 546 return getStructLayout(cast<StructType>(Ty))->getSizeInBits(); 547 case Type::IntegerTyID: 548 return Ty->getIntegerBitWidth(); 549 case Type::HalfTyID: 550 return 16; 551 case Type::FloatTyID: 552 return 32; 553 case Type::DoubleTyID: 554 case Type::X86_MMXTyID: 555 return 64; 556 case Type::PPC_FP128TyID: 557 case Type::FP128TyID: 558 return 128; 559 // In memory objects this is always aligned to a higher boundary, but 560 // only 80 bits contain information. 561 case Type::X86_FP80TyID: 562 return 80; 563 case Type::VectorTyID: { 564 VectorType *VTy = cast<VectorType>(Ty); 565 return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType()); 566 } 567 default: 568 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type"); 569 } 570 } 571 572 } // end namespace llvm 573 574 #endif // LLVM_IR_DATALAYOUT_H 575
