1 //===-- llvm/Target/TargetData.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 target 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_TARGET_TARGETDATA_H 21 #define LLVM_TARGET_TARGETDATA_H 22 23 #include "llvm/Pass.h" 24 #include "llvm/ADT/SmallVector.h" 25 #include "llvm/Support/DataTypes.h" 26 27 namespace llvm { 28 29 class Value; 30 class Type; 31 class IntegerType; 32 class StructType; 33 class StructLayout; 34 class GlobalVariable; 35 class LLVMContext; 36 template<typename T> 37 class ArrayRef; 38 39 /// Enum used to categorize the alignment types stored by TargetAlignElem 40 enum AlignTypeEnum { 41 INTEGER_ALIGN = 'i', ///< Integer type alignment 42 VECTOR_ALIGN = 'v', ///< Vector type alignment 43 FLOAT_ALIGN = 'f', ///< Floating point type alignment 44 AGGREGATE_ALIGN = 'a', ///< Aggregate alignment 45 STACK_ALIGN = 's' ///< Stack objects alignment 46 }; 47 48 /// Target alignment element. 49 /// 50 /// Stores the alignment data associated with a given alignment type (pointer, 51 /// integer, vector, float) and type bit width. 52 /// 53 /// @note The unusual order of elements in the structure attempts to reduce 54 /// padding and make the structure slightly more cache friendly. 55 struct TargetAlignElem { 56 AlignTypeEnum AlignType : 8; //< Alignment type (AlignTypeEnum) 57 unsigned ABIAlign; //< ABI alignment for this type/bitw 58 unsigned PrefAlign; //< Pref. alignment for this type/bitw 59 uint32_t TypeBitWidth; //< Type bit width 60 61 /// Initializer 62 static TargetAlignElem get(AlignTypeEnum align_type, unsigned abi_align, 63 unsigned pref_align, uint32_t bit_width); 64 /// Equality predicate 65 bool operator==(const TargetAlignElem &rhs) const; 66 }; 67 68 /// TargetData - This class holds a parsed version of the target data layout 69 /// string in a module and provides methods for querying it. The target data 70 /// layout string is specified *by the target* - a frontend generating LLVM IR 71 /// is required to generate the right target data for the target being codegen'd 72 /// to. If some measure of portability is desired, an empty string may be 73 /// specified in the module. 74 class TargetData : public ImmutablePass { 75 private: 76 bool LittleEndian; ///< Defaults to false 77 unsigned PointerMemSize; ///< Pointer size in bytes 78 unsigned PointerABIAlign; ///< Pointer ABI alignment 79 unsigned PointerPrefAlign; ///< Pointer preferred alignment 80 unsigned StackNaturalAlign; ///< Stack natural alignment 81 82 SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers. 83 84 /// Alignments- Where the primitive type alignment data is stored. 85 /// 86 /// @sa init(). 87 /// @note Could support multiple size pointer alignments, e.g., 32-bit 88 /// pointers vs. 64-bit pointers by extending TargetAlignment, but for now, 89 /// we don't. 90 SmallVector<TargetAlignElem, 16> Alignments; 91 92 /// InvalidAlignmentElem - This member is a signal that a requested alignment 93 /// type and bit width were not found in the SmallVector. 94 static const TargetAlignElem InvalidAlignmentElem; 95 96 // The StructType -> StructLayout map. 97 mutable void *LayoutMap; 98 99 //! Set/initialize target alignments 100 void setAlignment(AlignTypeEnum align_type, unsigned abi_align, 101 unsigned pref_align, uint32_t bit_width); 102 unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width, 103 bool ABIAlign, Type *Ty) const; 104 //! Internal helper method that returns requested alignment for type. 105 unsigned getAlignment(Type *Ty, bool abi_or_pref) const; 106 107 /// Valid alignment predicate. 108 /// 109 /// Predicate that tests a TargetAlignElem reference returned by get() against 110 /// InvalidAlignmentElem. 111 bool validAlignment(const TargetAlignElem &align) const { 112 return &align != &InvalidAlignmentElem; 113 } 114 115 public: 116 /// Default ctor. 117 /// 118 /// @note This has to exist, because this is a pass, but it should never be 119 /// used. 120 TargetData(); 121 122 /// Constructs a TargetData from a specification string. See init(). 123 explicit TargetData(StringRef TargetDescription) 124 : ImmutablePass(ID) { 125 init(TargetDescription); 126 } 127 128 /// Initialize target data from properties stored in the module. 129 explicit TargetData(const Module *M); 130 131 TargetData(const TargetData &TD) : 132 ImmutablePass(ID), 133 LittleEndian(TD.isLittleEndian()), 134 PointerMemSize(TD.PointerMemSize), 135 PointerABIAlign(TD.PointerABIAlign), 136 PointerPrefAlign(TD.PointerPrefAlign), 137 LegalIntWidths(TD.LegalIntWidths), 138 Alignments(TD.Alignments), 139 LayoutMap(0) 140 { } 141 142 ~TargetData(); // Not virtual, do not subclass this class 143 144 //! Parse a target data layout string and initialize TargetData alignments. 145 void init(StringRef TargetDescription); 146 147 /// Target endianness... 148 bool isLittleEndian() const { return LittleEndian; } 149 bool isBigEndian() const { return !LittleEndian; } 150 151 /// getStringRepresentation - Return the string representation of the 152 /// TargetData. This representation is in the same format accepted by the 153 /// string constructor above. 154 std::string getStringRepresentation() const; 155 156 /// isLegalInteger - This function returns true if the specified type is 157 /// known to be a native integer type supported by the CPU. For example, 158 /// i64 is not native on most 32-bit CPUs and i37 is not native on any known 159 /// one. This returns false if the integer width is not legal. 160 /// 161 /// The width is specified in bits. 162 /// 163 bool isLegalInteger(unsigned Width) const { 164 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i) 165 if (LegalIntWidths[i] == Width) 166 return true; 167 return false; 168 } 169 170 bool isIllegalInteger(unsigned Width) const { 171 return !isLegalInteger(Width); 172 } 173 174 /// Returns true if the given alignment exceeds the natural stack alignment. 175 bool exceedsNaturalStackAlignment(unsigned Align) const { 176 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign); 177 } 178 179 /// fitsInLegalInteger - This function returns true if the specified type fits 180 /// in a native integer type supported by the CPU. For example, if the CPU 181 /// only supports i32 as a native integer type, then i27 fits in a legal 182 // integer type but i45 does not. 183 bool fitsInLegalInteger(unsigned Width) const { 184 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i) 185 if (Width <= LegalIntWidths[i]) 186 return true; 187 return false; 188 } 189 190 /// Target pointer alignment 191 unsigned getPointerABIAlignment() const { return PointerABIAlign; } 192 /// Return target's alignment for stack-based pointers 193 unsigned getPointerPrefAlignment() const { return PointerPrefAlign; } 194 /// Target pointer size 195 unsigned getPointerSize() const { return PointerMemSize; } 196 /// Target pointer size, in bits 197 unsigned getPointerSizeInBits() const { return 8*PointerMemSize; } 198 199 /// Size examples: 200 /// 201 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*] 202 /// ---- ---------- --------------- --------------- 203 /// i1 1 8 8 204 /// i8 8 8 8 205 /// i19 19 24 32 206 /// i32 32 32 32 207 /// i100 100 104 128 208 /// i128 128 128 128 209 /// Float 32 32 32 210 /// Double 64 64 64 211 /// X86_FP80 80 80 96 212 /// 213 /// [*] The alloc size depends on the alignment, and thus on the target. 214 /// These values are for x86-32 linux. 215 216 /// getTypeSizeInBits - Return the number of bits necessary to hold the 217 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80. 218 uint64_t getTypeSizeInBits(Type* Ty) const; 219 220 /// getTypeStoreSize - Return the maximum number of bytes that may be 221 /// overwritten by storing the specified type. For example, returns 5 222 /// for i36 and 10 for x86_fp80. 223 uint64_t getTypeStoreSize(Type *Ty) const { 224 return (getTypeSizeInBits(Ty)+7)/8; 225 } 226 227 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be 228 /// overwritten by storing the specified type; always a multiple of 8. For 229 /// example, returns 40 for i36 and 80 for x86_fp80. 230 uint64_t getTypeStoreSizeInBits(Type *Ty) const { 231 return 8*getTypeStoreSize(Ty); 232 } 233 234 /// getTypeAllocSize - Return the offset in bytes between successive objects 235 /// of the specified type, including alignment padding. This is the amount 236 /// that alloca reserves for this type. For example, returns 12 or 16 for 237 /// x86_fp80, depending on alignment. 238 uint64_t getTypeAllocSize(Type* Ty) const { 239 // Round up to the next alignment boundary. 240 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty)); 241 } 242 243 /// getTypeAllocSizeInBits - Return the offset in bits between successive 244 /// objects of the specified type, including alignment padding; always a 245 /// multiple of 8. This is the amount that alloca reserves for this type. 246 /// For example, returns 96 or 128 for x86_fp80, depending on alignment. 247 uint64_t getTypeAllocSizeInBits(Type* Ty) const { 248 return 8*getTypeAllocSize(Ty); 249 } 250 251 /// getABITypeAlignment - Return the minimum ABI-required alignment for the 252 /// specified type. 253 unsigned getABITypeAlignment(Type *Ty) const; 254 255 /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for 256 /// an integer type of the specified bitwidth. 257 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const; 258 259 260 /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment 261 /// for the specified type when it is part of a call frame. 262 unsigned getCallFrameTypeAlignment(Type *Ty) const; 263 264 265 /// getPrefTypeAlignment - Return the preferred stack/global alignment for 266 /// the specified type. This is always at least as good as the ABI alignment. 267 unsigned getPrefTypeAlignment(Type *Ty) const; 268 269 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the 270 /// specified type, returned as log2 of the value (a shift amount). 271 /// 272 unsigned getPreferredTypeAlignmentShift(Type *Ty) const; 273 274 /// getIntPtrType - Return an unsigned integer type that is the same size or 275 /// greater to the host pointer size. 276 /// 277 IntegerType *getIntPtrType(LLVMContext &C) const; 278 279 /// getIndexedOffset - return the offset from the beginning of the type for 280 /// the specified indices. This is used to implement getelementptr. 281 /// 282 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const; 283 284 /// getStructLayout - Return a StructLayout object, indicating the alignment 285 /// of the struct, its size, and the offsets of its fields. Note that this 286 /// information is lazily cached. 287 const StructLayout *getStructLayout(StructType *Ty) const; 288 289 /// getPreferredAlignment - Return the preferred alignment of the specified 290 /// global. This includes an explicitly requested alignment (if the global 291 /// has one). 292 unsigned getPreferredAlignment(const GlobalVariable *GV) const; 293 294 /// getPreferredAlignmentLog - Return the preferred alignment of the 295 /// specified global, returned in log form. This includes an explicitly 296 /// requested alignment (if the global has one). 297 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const; 298 299 /// RoundUpAlignment - Round the specified value up to the next alignment 300 /// boundary specified by Alignment. For example, 7 rounded up to an 301 /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4 302 /// is 8 because it is already aligned. 303 template <typename UIntTy> 304 static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) { 305 assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!"); 306 return (Val + (Alignment-1)) & ~UIntTy(Alignment-1); 307 } 308 309 static char ID; // Pass identification, replacement for typeid 310 }; 311 312 /// StructLayout - used to lazily calculate structure layout information for a 313 /// target machine, based on the TargetData structure. 314 /// 315 class StructLayout { 316 uint64_t StructSize; 317 unsigned StructAlignment; 318 unsigned NumElements; 319 uint64_t MemberOffsets[1]; // variable sized array! 320 public: 321 322 uint64_t getSizeInBytes() const { 323 return StructSize; 324 } 325 326 uint64_t getSizeInBits() const { 327 return 8*StructSize; 328 } 329 330 unsigned getAlignment() const { 331 return StructAlignment; 332 } 333 334 /// getElementContainingOffset - Given a valid byte offset into the structure, 335 /// return the structure index that contains it. 336 /// 337 unsigned getElementContainingOffset(uint64_t Offset) const; 338 339 uint64_t getElementOffset(unsigned Idx) const { 340 assert(Idx < NumElements && "Invalid element idx!"); 341 return MemberOffsets[Idx]; 342 } 343 344 uint64_t getElementOffsetInBits(unsigned Idx) const { 345 return getElementOffset(Idx)*8; 346 } 347 348 private: 349 friend class TargetData; // Only TargetData can create this class 350 StructLayout(StructType *ST, const TargetData &TD); 351 }; 352 353 } // End llvm namespace 354 355 #endif 356
