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 namespace llvm { 31 32 class Value; 33 class Type; 34 class IntegerType; 35 class StructType; 36 class StructLayout; 37 class GlobalVariable; 38 class LLVMContext; 39 template<typename T> 40 class ArrayRef; 41 42 /// Enum used to categorize the alignment types stored by LayoutAlignElem 43 enum AlignTypeEnum { 44 INVALID_ALIGN = 0, ///< An invalid alignment 45 INTEGER_ALIGN = 'i', ///< Integer type alignment 46 VECTOR_ALIGN = 'v', ///< Vector type alignment 47 FLOAT_ALIGN = 'f', ///< Floating point type alignment 48 AGGREGATE_ALIGN = 'a', ///< Aggregate alignment 49 STACK_ALIGN = 's' ///< Stack objects alignment 50 }; 51 52 /// Layout alignment element. 53 /// 54 /// Stores the alignment data associated with a given alignment type (integer, 55 /// vector, float) and type bit width. 56 /// 57 /// @note The unusual order of elements in the structure attempts to reduce 58 /// padding and make the structure slightly more cache friendly. 59 struct LayoutAlignElem { 60 unsigned AlignType : 8; ///< Alignment type (AlignTypeEnum) 61 unsigned TypeBitWidth : 24; ///< Type bit width 62 unsigned ABIAlign : 16; ///< ABI alignment for this type/bitw 63 unsigned PrefAlign : 16; ///< Pref. alignment for this type/bitw 64 65 /// Initializer 66 static LayoutAlignElem get(AlignTypeEnum align_type, unsigned abi_align, 67 unsigned pref_align, uint32_t bit_width); 68 /// Equality predicate 69 bool operator==(const LayoutAlignElem &rhs) const; 70 }; 71 72 /// Layout pointer alignment element. 73 /// 74 /// Stores the alignment data associated with a given pointer and address space. 75 /// 76 /// @note The unusual order of elements in the structure attempts to reduce 77 /// padding and make the structure slightly more cache friendly. 78 struct PointerAlignElem { 79 unsigned ABIAlign; ///< ABI alignment for this type/bitw 80 unsigned PrefAlign; ///< Pref. alignment for this type/bitw 81 uint32_t TypeBitWidth; ///< Type bit width 82 uint32_t AddressSpace; ///< Address space for the pointer type 83 84 /// Initializer 85 static PointerAlignElem get(uint32_t addr_space, unsigned abi_align, 86 unsigned pref_align, uint32_t bit_width); 87 /// Equality predicate 88 bool operator==(const PointerAlignElem &rhs) const; 89 }; 90 91 92 /// DataLayout - This class holds a parsed version of the target data layout 93 /// string in a module and provides methods for querying it. The target data 94 /// layout string is specified *by the target* - a frontend generating LLVM IR 95 /// is required to generate the right target data for the target being codegen'd 96 /// to. If some measure of portability is desired, an empty string may be 97 /// specified in the module. 98 class DataLayout : public ImmutablePass { 99 private: 100 bool LittleEndian; ///< Defaults to false 101 unsigned StackNaturalAlign; ///< Stack natural alignment 102 103 SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers. 104 105 /// Alignments - Where the primitive type alignment data is stored. 106 /// 107 /// @sa init(). 108 /// @note Could support multiple size pointer alignments, e.g., 32-bit 109 /// pointers vs. 64-bit pointers by extending LayoutAlignment, but for now, 110 /// we don't. 111 SmallVector<LayoutAlignElem, 16> Alignments; 112 DenseMap<unsigned, PointerAlignElem> Pointers; 113 114 /// InvalidAlignmentElem - This member is a signal that a requested alignment 115 /// type and bit width were not found in the SmallVector. 116 static const LayoutAlignElem InvalidAlignmentElem; 117 118 /// InvalidPointerElem - This member is a signal that a requested pointer 119 /// type and bit width were not found in the DenseSet. 120 static const PointerAlignElem InvalidPointerElem; 121 122 // The StructType -> StructLayout map. 123 mutable void *LayoutMap; 124 125 //! Set/initialize target alignments 126 void setAlignment(AlignTypeEnum align_type, unsigned abi_align, 127 unsigned pref_align, uint32_t bit_width); 128 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width, 129 bool ABIAlign, Type *Ty) const; 130 131 //! Set/initialize pointer alignments 132 void setPointerAlignment(uint32_t addr_space, unsigned abi_align, 133 unsigned pref_align, uint32_t bit_width); 134 135 //! Internal helper method that returns requested alignment for type. 136 unsigned getAlignment(Type *Ty, bool abi_or_pref) const; 137 138 /// Valid alignment predicate. 139 /// 140 /// Predicate that tests a LayoutAlignElem reference returned by get() against 141 /// InvalidAlignmentElem. 142 bool validAlignment(const LayoutAlignElem &align) const { 143 return &align != &InvalidAlignmentElem; 144 } 145 146 /// Valid pointer predicate. 147 /// 148 /// Predicate that tests a PointerAlignElem reference returned by get() against 149 /// InvalidPointerElem. 150 bool validPointer(const PointerAlignElem &align) const { 151 return &align != &InvalidPointerElem; 152 } 153 154 /// Parses a target data specification string. Assert if the string is 155 /// malformed. 156 void parseSpecifier(StringRef LayoutDescription); 157 158 public: 159 /// Default ctor. 160 /// 161 /// @note This has to exist, because this is a pass, but it should never be 162 /// used. 163 DataLayout(); 164 165 /// Constructs a DataLayout from a specification string. See init(). 166 explicit DataLayout(StringRef LayoutDescription) 167 : ImmutablePass(ID) { 168 init(LayoutDescription); 169 } 170 171 /// Initialize target data from properties stored in the module. 172 explicit DataLayout(const Module *M); 173 174 DataLayout(const DataLayout &DL) : 175 ImmutablePass(ID), 176 LittleEndian(DL.isLittleEndian()), 177 StackNaturalAlign(DL.StackNaturalAlign), 178 LegalIntWidths(DL.LegalIntWidths), 179 Alignments(DL.Alignments), 180 Pointers(DL.Pointers), 181 LayoutMap(0) 182 { } 183 184 ~DataLayout(); // Not virtual, do not subclass this class 185 186 /// DataLayout is an immutable pass, but holds state. This allows the pass 187 /// manager to clear its mutable state. 188 bool doFinalization(Module &M); 189 190 /// Parse a data layout string (with fallback to default values). Ensure that 191 /// the data layout pass is registered. 192 void init(StringRef LayoutDescription); 193 194 /// Layout endianness... 195 bool isLittleEndian() const { return LittleEndian; } 196 bool isBigEndian() const { return !LittleEndian; } 197 198 /// getStringRepresentation - Return the string representation of the 199 /// DataLayout. This representation is in the same format accepted by the 200 /// string constructor above. 201 std::string getStringRepresentation() const; 202 203 /// isLegalInteger - This function returns true if the specified type is 204 /// known to be a native integer type supported by the CPU. For example, 205 /// i64 is not native on most 32-bit CPUs and i37 is not native on any known 206 /// one. This returns false if the integer width is not legal. 207 /// 208 /// The width is specified in bits. 209 /// 210 bool isLegalInteger(unsigned Width) const { 211 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i) 212 if (LegalIntWidths[i] == Width) 213 return true; 214 return false; 215 } 216 217 bool isIllegalInteger(unsigned Width) const { 218 return !isLegalInteger(Width); 219 } 220 221 /// Returns true if the given alignment exceeds the natural stack alignment. 222 bool exceedsNaturalStackAlignment(unsigned Align) const { 223 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign); 224 } 225 226 /// fitsInLegalInteger - This function returns true if the specified type fits 227 /// in a native integer type supported by the CPU. For example, if the CPU 228 /// only supports i32 as a native integer type, then i27 fits in a legal 229 // integer type but i45 does not. 230 bool fitsInLegalInteger(unsigned Width) const { 231 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i) 232 if (Width <= LegalIntWidths[i]) 233 return true; 234 return false; 235 } 236 237 /// Layout pointer alignment 238 /// FIXME: The defaults need to be removed once all of 239 /// the backends/clients are updated. 240 unsigned getPointerABIAlignment(unsigned AS = 0) const { 241 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS); 242 if (val == Pointers.end()) { 243 val = Pointers.find(0); 244 } 245 return val->second.ABIAlign; 246 } 247 248 /// Return target's alignment for stack-based pointers 249 /// FIXME: The defaults need to be removed once all of 250 /// the backends/clients are updated. 251 unsigned getPointerPrefAlignment(unsigned AS = 0) const { 252 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS); 253 if (val == Pointers.end()) { 254 val = Pointers.find(0); 255 } 256 return val->second.PrefAlign; 257 } 258 /// Layout pointer size 259 /// FIXME: The defaults need to be removed once all of 260 /// the backends/clients are updated. 261 unsigned getPointerSize(unsigned AS = 0) const { 262 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS); 263 if (val == Pointers.end()) { 264 val = Pointers.find(0); 265 } 266 return val->second.TypeBitWidth; 267 } 268 /// Layout pointer size, in bits 269 /// FIXME: The defaults need to be removed once all of 270 /// the backends/clients are updated. 271 unsigned getPointerSizeInBits(unsigned AS = 0) const { 272 return getPointerSize(AS) * 8; 273 } 274 275 /// Layout pointer size, in bits, based on the type. If this function is 276 /// called with a pointer type, then the type size of the pointer is returned. 277 /// If this function is called with a vector of pointers, then the type size 278 /// of the pointer is returned. This should only be called with a pointer or 279 /// vector of pointers. 280 unsigned getPointerTypeSizeInBits(Type *) const; 281 282 unsigned getPointerTypeSize(Type *Ty) const { 283 return getPointerTypeSizeInBits(Ty) / 8; 284 } 285 286 /// Size examples: 287 /// 288 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*] 289 /// ---- ---------- --------------- --------------- 290 /// i1 1 8 8 291 /// i8 8 8 8 292 /// i19 19 24 32 293 /// i32 32 32 32 294 /// i100 100 104 128 295 /// i128 128 128 128 296 /// Float 32 32 32 297 /// Double 64 64 64 298 /// X86_FP80 80 80 96 299 /// 300 /// [*] The alloc size depends on the alignment, and thus on the target. 301 /// These values are for x86-32 linux. 302 303 /// getTypeSizeInBits - Return the number of bits necessary to hold the 304 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80. 305 /// The type passed must have a size (Type::isSized() must return true). 306 uint64_t getTypeSizeInBits(Type *Ty) const; 307 308 /// getTypeStoreSize - Return the maximum number of bytes that may be 309 /// overwritten by storing the specified type. For example, returns 5 310 /// for i36 and 10 for x86_fp80. 311 uint64_t getTypeStoreSize(Type *Ty) const { 312 return (getTypeSizeInBits(Ty)+7)/8; 313 } 314 315 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be 316 /// overwritten by storing the specified type; always a multiple of 8. For 317 /// example, returns 40 for i36 and 80 for x86_fp80. 318 uint64_t getTypeStoreSizeInBits(Type *Ty) const { 319 return 8*getTypeStoreSize(Ty); 320 } 321 322 /// getTypeAllocSize - Return the offset in bytes between successive objects 323 /// of the specified type, including alignment padding. This is the amount 324 /// that alloca reserves for this type. For example, returns 12 or 16 for 325 /// x86_fp80, depending on alignment. 326 uint64_t getTypeAllocSize(Type *Ty) const { 327 // Round up to the next alignment boundary. 328 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty)); 329 } 330 331 /// getTypeAllocSizeInBits - Return the offset in bits between successive 332 /// objects of the specified type, including alignment padding; always a 333 /// multiple of 8. This is the amount that alloca reserves for this type. 334 /// For example, returns 96 or 128 for x86_fp80, depending on alignment. 335 uint64_t getTypeAllocSizeInBits(Type *Ty) const { 336 return 8*getTypeAllocSize(Ty); 337 } 338 339 /// getABITypeAlignment - Return the minimum ABI-required alignment for the 340 /// specified type. 341 unsigned getABITypeAlignment(Type *Ty) const; 342 343 /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for 344 /// an integer type of the specified bitwidth. 345 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const; 346 347 /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment 348 /// for the specified type when it is part of a call frame. 349 unsigned getCallFrameTypeAlignment(Type *Ty) const; 350 351 /// getPrefTypeAlignment - Return the preferred stack/global alignment for 352 /// the specified type. This is always at least as good as the ABI alignment. 353 unsigned getPrefTypeAlignment(Type *Ty) const; 354 355 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the 356 /// specified type, returned as log2 of the value (a shift amount). 357 unsigned getPreferredTypeAlignmentShift(Type *Ty) const; 358 359 /// getIntPtrType - Return an integer type with size at least as big as that 360 /// of a pointer in the given address space. 361 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const; 362 363 /// getIntPtrType - Return an integer (vector of integer) type with size at 364 /// least as big as that of a pointer of the given pointer (vector of pointer) 365 /// type. 366 Type *getIntPtrType(Type *) const; 367 368 /// getSmallestLegalIntType - Return the smallest integer type with size at 369 /// least as big as Width bits. 370 Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const; 371 372 /// getIndexedOffset - return the offset from the beginning of the type for 373 /// the specified indices. This is used to implement getelementptr. 374 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const; 375 376 /// getStructLayout - Return a StructLayout object, indicating the alignment 377 /// of the struct, its size, and the offsets of its fields. Note that this 378 /// information is lazily cached. 379 const StructLayout *getStructLayout(StructType *Ty) const; 380 381 /// getPreferredAlignment - Return the preferred alignment of the specified 382 /// global. This includes an explicitly requested alignment (if the global 383 /// has one). 384 unsigned getPreferredAlignment(const GlobalVariable *GV) const; 385 386 /// getPreferredAlignmentLog - Return the preferred alignment of the 387 /// specified global, returned in log form. This includes an explicitly 388 /// requested alignment (if the global has one). 389 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const; 390 391 /// RoundUpAlignment - Round the specified value up to the next alignment 392 /// boundary specified by Alignment. For example, 7 rounded up to an 393 /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4 394 /// is 8 because it is already aligned. 395 template <typename UIntTy> 396 static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) { 397 assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!"); 398 return (Val + (Alignment-1)) & ~UIntTy(Alignment-1); 399 } 400 401 static char ID; // Pass identification, replacement for typeid 402 }; 403 404 /// StructLayout - used to lazily calculate structure layout information for a 405 /// target machine, based on the DataLayout structure. 406 /// 407 class StructLayout { 408 uint64_t StructSize; 409 unsigned StructAlignment; 410 unsigned NumElements; 411 uint64_t MemberOffsets[1]; // variable sized array! 412 public: 413 414 uint64_t getSizeInBytes() const { 415 return StructSize; 416 } 417 418 uint64_t getSizeInBits() const { 419 return 8*StructSize; 420 } 421 422 unsigned getAlignment() const { 423 return StructAlignment; 424 } 425 426 /// getElementContainingOffset - Given a valid byte offset into the structure, 427 /// return the structure index that contains it. 428 /// 429 unsigned getElementContainingOffset(uint64_t Offset) const; 430 431 uint64_t getElementOffset(unsigned Idx) const { 432 assert(Idx < NumElements && "Invalid element idx!"); 433 return MemberOffsets[Idx]; 434 } 435 436 uint64_t getElementOffsetInBits(unsigned Idx) const { 437 return getElementOffset(Idx)*8; 438 } 439 440 private: 441 friend class DataLayout; // Only DataLayout can create this class 442 StructLayout(StructType *ST, const DataLayout &DL); 443 }; 444 445 446 // The implementation of this method is provided inline as it is particularly 447 // well suited to constant folding when called on a specific Type subclass. 448 inline uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const { 449 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!"); 450 switch (Ty->getTypeID()) { 451 case Type::LabelTyID: 452 return getPointerSizeInBits(0); 453 case Type::PointerTyID: 454 return getPointerSizeInBits(cast<PointerType>(Ty)->getAddressSpace()); 455 case Type::ArrayTyID: { 456 ArrayType *ATy = cast<ArrayType>(Ty); 457 return ATy->getNumElements() * 458 getTypeAllocSizeInBits(ATy->getElementType()); 459 } 460 case Type::StructTyID: 461 // Get the layout annotation... which is lazily created on demand. 462 return getStructLayout(cast<StructType>(Ty))->getSizeInBits(); 463 case Type::IntegerTyID: 464 return cast<IntegerType>(Ty)->getBitWidth(); 465 case Type::HalfTyID: 466 return 16; 467 case Type::FloatTyID: 468 return 32; 469 case Type::DoubleTyID: 470 case Type::X86_MMXTyID: 471 return 64; 472 case Type::PPC_FP128TyID: 473 case Type::FP128TyID: 474 return 128; 475 // In memory objects this is always aligned to a higher boundary, but 476 // only 80 bits contain information. 477 case Type::X86_FP80TyID: 478 return 80; 479 case Type::VectorTyID: { 480 VectorType *VTy = cast<VectorType>(Ty); 481 return VTy->getNumElements() * getTypeSizeInBits(VTy->getElementType()); 482 } 483 default: 484 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type"); 485 } 486 } 487 488 } // End llvm namespace 489 490 #endif 491
