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/Pass.h" 26 #include "llvm/Support/DataTypes.h" 27 28 namespace llvm { 29 30 class Value; 31 class Type; 32 class IntegerType; 33 class StructType; 34 class StructLayout; 35 class GlobalVariable; 36 class LLVMContext; 37 template<typename T> 38 class ArrayRef; 39 40 /// Enum used to categorize the alignment types stored by LayoutAlignElem 41 enum AlignTypeEnum { 42 INVALID_ALIGN = 0, ///< An invalid alignment 43 INTEGER_ALIGN = 'i', ///< Integer type alignment 44 VECTOR_ALIGN = 'v', ///< Vector type alignment 45 FLOAT_ALIGN = 'f', ///< Floating point type alignment 46 AGGREGATE_ALIGN = 'a', ///< Aggregate alignment 47 STACK_ALIGN = 's' ///< Stack objects alignment 48 }; 49 50 /// Layout alignment element. 51 /// 52 /// Stores the alignment data associated with a given alignment type (integer, 53 /// vector, float) and type bit width. 54 /// 55 /// @note The unusual order of elements in the structure attempts to reduce 56 /// padding and make the structure slightly more cache friendly. 57 struct LayoutAlignElem { 58 unsigned AlignType : 8; ///< Alignment type (AlignTypeEnum) 59 unsigned TypeBitWidth : 24; ///< Type bit width 60 unsigned ABIAlign : 16; ///< ABI alignment for this type/bitw 61 unsigned PrefAlign : 16; ///< Pref. alignment for this type/bitw 62 63 /// Initializer 64 static LayoutAlignElem get(AlignTypeEnum align_type, unsigned abi_align, 65 unsigned pref_align, uint32_t bit_width); 66 /// Equality predicate 67 bool operator==(const LayoutAlignElem &rhs) const; 68 }; 69 70 /// Layout pointer alignment element. 71 /// 72 /// Stores the alignment data associated with a given pointer and address space. 73 /// 74 /// @note The unusual order of elements in the structure attempts to reduce 75 /// padding and make the structure slightly more cache friendly. 76 struct PointerAlignElem { 77 unsigned ABIAlign; ///< ABI alignment for this type/bitw 78 unsigned PrefAlign; ///< Pref. alignment for this type/bitw 79 uint32_t TypeBitWidth; ///< Type bit width 80 uint32_t AddressSpace; ///< Address space for the pointer type 81 82 /// Initializer 83 static PointerAlignElem get(uint32_t addr_space, unsigned abi_align, 84 unsigned pref_align, uint32_t bit_width); 85 /// Equality predicate 86 bool operator==(const PointerAlignElem &rhs) const; 87 }; 88 89 90 /// DataLayout - This class holds a parsed version of the target data layout 91 /// string in a module and provides methods for querying it. The target data 92 /// layout string is specified *by the target* - a frontend generating LLVM IR 93 /// is required to generate the right target data for the target being codegen'd 94 /// to. If some measure of portability is desired, an empty string may be 95 /// specified in the module. 96 class DataLayout : public ImmutablePass { 97 private: 98 bool LittleEndian; ///< Defaults to false 99 unsigned StackNaturalAlign; ///< Stack natural alignment 100 101 SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers. 102 103 /// Alignments - Where the primitive type alignment data is stored. 104 /// 105 /// @sa init(). 106 /// @note Could support multiple size pointer alignments, e.g., 32-bit 107 /// pointers vs. 64-bit pointers by extending LayoutAlignment, but for now, 108 /// we don't. 109 SmallVector<LayoutAlignElem, 16> Alignments; 110 DenseMap<unsigned, PointerAlignElem> Pointers; 111 112 /// InvalidAlignmentElem - This member is a signal that a requested alignment 113 /// type and bit width were not found in the SmallVector. 114 static const LayoutAlignElem InvalidAlignmentElem; 115 116 /// InvalidPointerElem - This member is a signal that a requested pointer 117 /// type and bit width were not found in the DenseSet. 118 static const PointerAlignElem InvalidPointerElem; 119 120 // The StructType -> StructLayout map. 121 mutable void *LayoutMap; 122 123 //! Set/initialize target alignments 124 void setAlignment(AlignTypeEnum align_type, unsigned abi_align, 125 unsigned pref_align, uint32_t bit_width); 126 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width, 127 bool ABIAlign, Type *Ty) const; 128 129 //! Set/initialize pointer alignments 130 void setPointerAlignment(uint32_t addr_space, unsigned abi_align, 131 unsigned pref_align, uint32_t bit_width); 132 133 //! Internal helper method that returns requested alignment for type. 134 unsigned getAlignment(Type *Ty, bool abi_or_pref) const; 135 136 /// Valid alignment predicate. 137 /// 138 /// Predicate that tests a LayoutAlignElem reference returned by get() against 139 /// InvalidAlignmentElem. 140 bool validAlignment(const LayoutAlignElem &align) const { 141 return &align != &InvalidAlignmentElem; 142 } 143 144 /// Valid pointer predicate. 145 /// 146 /// Predicate that tests a PointerAlignElem reference returned by get() against 147 /// InvalidPointerElem. 148 bool validPointer(const PointerAlignElem &align) const { 149 return &align != &InvalidPointerElem; 150 } 151 152 /// Parses a target data specification string. Assert if the string is 153 /// malformed. 154 void parseSpecifier(StringRef LayoutDescription); 155 156 public: 157 /// Default ctor. 158 /// 159 /// @note This has to exist, because this is a pass, but it should never be 160 /// used. 161 DataLayout(); 162 163 /// Constructs a DataLayout from a specification string. See init(). 164 explicit DataLayout(StringRef LayoutDescription) 165 : ImmutablePass(ID) { 166 init(LayoutDescription); 167 } 168 169 /// Initialize target data from properties stored in the module. 170 explicit DataLayout(const Module *M); 171 172 DataLayout(const DataLayout &TD) : 173 ImmutablePass(ID), 174 LittleEndian(TD.isLittleEndian()), 175 StackNaturalAlign(TD.StackNaturalAlign), 176 LegalIntWidths(TD.LegalIntWidths), 177 Alignments(TD.Alignments), 178 Pointers(TD.Pointers), 179 LayoutMap(0) 180 { } 181 182 ~DataLayout(); // Not virtual, do not subclass this class 183 184 /// DataLayout is an immutable pass, but holds state. This allows the pass 185 /// manager to clear its mutable state. 186 bool doFinalization(Module &M); 187 188 /// Parse a data layout string (with fallback to default values). Ensure that 189 /// the data layout pass is registered. 190 void init(StringRef LayoutDescription); 191 192 /// Layout endianness... 193 bool isLittleEndian() const { return LittleEndian; } 194 bool isBigEndian() const { return !LittleEndian; } 195 196 /// getStringRepresentation - Return the string representation of the 197 /// DataLayout. This representation is in the same format accepted by the 198 /// string constructor above. 199 std::string getStringRepresentation() const; 200 201 /// isLegalInteger - This function returns true if the specified type is 202 /// known to be a native integer type supported by the CPU. For example, 203 /// i64 is not native on most 32-bit CPUs and i37 is not native on any known 204 /// one. This returns false if the integer width is not legal. 205 /// 206 /// The width is specified in bits. 207 /// 208 bool isLegalInteger(unsigned Width) const { 209 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i) 210 if (LegalIntWidths[i] == Width) 211 return true; 212 return false; 213 } 214 215 bool isIllegalInteger(unsigned Width) const { 216 return !isLegalInteger(Width); 217 } 218 219 /// Returns true if the given alignment exceeds the natural stack alignment. 220 bool exceedsNaturalStackAlignment(unsigned Align) const { 221 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign); 222 } 223 224 /// fitsInLegalInteger - This function returns true if the specified type fits 225 /// in a native integer type supported by the CPU. For example, if the CPU 226 /// only supports i32 as a native integer type, then i27 fits in a legal 227 // integer type but i45 does not. 228 bool fitsInLegalInteger(unsigned Width) const { 229 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i) 230 if (Width <= LegalIntWidths[i]) 231 return true; 232 return false; 233 } 234 235 /// Layout pointer alignment 236 /// FIXME: The defaults need to be removed once all of 237 /// the backends/clients are updated. 238 unsigned getPointerABIAlignment(unsigned AS = 0) const { 239 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS); 240 if (val == Pointers.end()) { 241 val = Pointers.find(0); 242 } 243 return val->second.ABIAlign; 244 } 245 /// Return target's alignment for stack-based pointers 246 /// FIXME: The defaults need to be removed once all of 247 /// the backends/clients are updated. 248 unsigned getPointerPrefAlignment(unsigned AS = 0) const { 249 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS); 250 if (val == Pointers.end()) { 251 val = Pointers.find(0); 252 } 253 return val->second.PrefAlign; 254 } 255 /// Layout pointer size 256 /// FIXME: The defaults need to be removed once all of 257 /// the backends/clients are updated. 258 unsigned getPointerSize(unsigned AS = 0) const { 259 DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS); 260 if (val == Pointers.end()) { 261 val = Pointers.find(0); 262 } 263 return val->second.TypeBitWidth; 264 } 265 /// Layout pointer size, in bits 266 /// FIXME: The defaults need to be removed once all of 267 /// the backends/clients are updated. 268 unsigned getPointerSizeInBits(unsigned AS = 0) const { 269 return getPointerSize(AS) * 8; 270 } 271 /// Size examples: 272 /// 273 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*] 274 /// ---- ---------- --------------- --------------- 275 /// i1 1 8 8 276 /// i8 8 8 8 277 /// i19 19 24 32 278 /// i32 32 32 32 279 /// i100 100 104 128 280 /// i128 128 128 128 281 /// Float 32 32 32 282 /// Double 64 64 64 283 /// X86_FP80 80 80 96 284 /// 285 /// [*] The alloc size depends on the alignment, and thus on the target. 286 /// These values are for x86-32 linux. 287 288 /// getTypeSizeInBits - Return the number of bits necessary to hold the 289 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80. 290 /// The type passed must have a size (Type::isSized() must return true). 291 uint64_t getTypeSizeInBits(Type *Ty) const; 292 293 /// getTypeStoreSize - Return the maximum number of bytes that may be 294 /// overwritten by storing the specified type. For example, returns 5 295 /// for i36 and 10 for x86_fp80. 296 uint64_t getTypeStoreSize(Type *Ty) const { 297 return (getTypeSizeInBits(Ty)+7)/8; 298 } 299 300 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be 301 /// overwritten by storing the specified type; always a multiple of 8. For 302 /// example, returns 40 for i36 and 80 for x86_fp80. 303 uint64_t getTypeStoreSizeInBits(Type *Ty) const { 304 return 8*getTypeStoreSize(Ty); 305 } 306 307 /// getTypeAllocSize - Return the offset in bytes between successive objects 308 /// of the specified type, including alignment padding. This is the amount 309 /// that alloca reserves for this type. For example, returns 12 or 16 for 310 /// x86_fp80, depending on alignment. 311 uint64_t getTypeAllocSize(Type *Ty) const { 312 // Round up to the next alignment boundary. 313 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty)); 314 } 315 316 /// getTypeAllocSizeInBits - Return the offset in bits between successive 317 /// objects of the specified type, including alignment padding; always a 318 /// multiple of 8. This is the amount that alloca reserves for this type. 319 /// For example, returns 96 or 128 for x86_fp80, depending on alignment. 320 uint64_t getTypeAllocSizeInBits(Type *Ty) const { 321 return 8*getTypeAllocSize(Ty); 322 } 323 324 /// getABITypeAlignment - Return the minimum ABI-required alignment for the 325 /// specified type. 326 unsigned getABITypeAlignment(Type *Ty) const; 327 328 /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for 329 /// an integer type of the specified bitwidth. 330 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const; 331 332 /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment 333 /// for the specified type when it is part of a call frame. 334 unsigned getCallFrameTypeAlignment(Type *Ty) const; 335 336 /// getPrefTypeAlignment - Return the preferred stack/global alignment for 337 /// the specified type. This is always at least as good as the ABI alignment. 338 unsigned getPrefTypeAlignment(Type *Ty) const; 339 340 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the 341 /// specified type, returned as log2 of the value (a shift amount). 342 unsigned getPreferredTypeAlignmentShift(Type *Ty) const; 343 344 /// getIntPtrType - Return an integer type with size at least as big as that 345 /// of a pointer in the given address space. 346 IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const; 347 348 /// getIntPtrType - Return an integer (vector of integer) type with size at 349 /// least as big as that of a pointer of the given pointer (vector of pointer) 350 /// type. 351 Type *getIntPtrType(Type *) const; 352 353 /// getIndexedOffset - return the offset from the beginning of the type for 354 /// the specified indices. This is used to implement getelementptr. 355 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const; 356 357 /// getStructLayout - Return a StructLayout object, indicating the alignment 358 /// of the struct, its size, and the offsets of its fields. Note that this 359 /// information is lazily cached. 360 const StructLayout *getStructLayout(StructType *Ty) const; 361 362 /// getPreferredAlignment - Return the preferred alignment of the specified 363 /// global. This includes an explicitly requested alignment (if the global 364 /// has one). 365 unsigned getPreferredAlignment(const GlobalVariable *GV) const; 366 367 /// getPreferredAlignmentLog - Return the preferred alignment of the 368 /// specified global, returned in log form. This includes an explicitly 369 /// requested alignment (if the global has one). 370 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const; 371 372 /// RoundUpAlignment - Round the specified value up to the next alignment 373 /// boundary specified by Alignment. For example, 7 rounded up to an 374 /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4 375 /// is 8 because it is already aligned. 376 template <typename UIntTy> 377 static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) { 378 assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!"); 379 return (Val + (Alignment-1)) & ~UIntTy(Alignment-1); 380 } 381 382 static char ID; // Pass identification, replacement for typeid 383 }; 384 385 /// StructLayout - used to lazily calculate structure layout information for a 386 /// target machine, based on the DataLayout structure. 387 /// 388 class StructLayout { 389 uint64_t StructSize; 390 unsigned StructAlignment; 391 unsigned NumElements; 392 uint64_t MemberOffsets[1]; // variable sized array! 393 public: 394 395 uint64_t getSizeInBytes() const { 396 return StructSize; 397 } 398 399 uint64_t getSizeInBits() const { 400 return 8*StructSize; 401 } 402 403 unsigned getAlignment() const { 404 return StructAlignment; 405 } 406 407 /// getElementContainingOffset - Given a valid byte offset into the structure, 408 /// return the structure index that contains it. 409 /// 410 unsigned getElementContainingOffset(uint64_t Offset) const; 411 412 uint64_t getElementOffset(unsigned Idx) const { 413 assert(Idx < NumElements && "Invalid element idx!"); 414 return MemberOffsets[Idx]; 415 } 416 417 uint64_t getElementOffsetInBits(unsigned Idx) const { 418 return getElementOffset(Idx)*8; 419 } 420 421 private: 422 friend class DataLayout; // Only DataLayout can create this class 423 StructLayout(StructType *ST, const DataLayout &TD); 424 }; 425 426 } // End llvm namespace 427 428 #endif 429
