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. validAlignment(const TargetAlignElem & align)111 bool validAlignment(const TargetAlignElem &align) const { 112 return &align != &InvalidAlignmentElem; 113 } 114 115 /// Initialise a TargetData object with default values, ensure that the 116 /// target data pass is registered. 117 void init(); 118 119 public: 120 /// Default ctor. 121 /// 122 /// @note This has to exist, because this is a pass, but it should never be 123 /// used. 124 TargetData(); 125 126 /// Constructs a TargetData from a specification string. See init(). TargetData(StringRef TargetDescription)127 explicit TargetData(StringRef TargetDescription) 128 : ImmutablePass(ID) { 129 std::string errMsg = parseSpecifier(TargetDescription, this); 130 assert(errMsg == "" && "Invalid target data layout string."); 131 (void)errMsg; 132 } 133 134 /// Parses a target data specification string. Returns an error message 135 /// if the string is malformed, or the empty string on success. Optionally 136 /// initialises a TargetData object if passed a non-null pointer. 137 static std::string parseSpecifier(StringRef TargetDescription, TargetData* td = 0); 138 139 /// Initialize target data from properties stored in the module. 140 explicit TargetData(const Module *M); 141 TargetData(const TargetData & TD)142 TargetData(const TargetData &TD) : 143 ImmutablePass(ID), 144 LittleEndian(TD.isLittleEndian()), 145 PointerMemSize(TD.PointerMemSize), 146 PointerABIAlign(TD.PointerABIAlign), 147 PointerPrefAlign(TD.PointerPrefAlign), 148 LegalIntWidths(TD.LegalIntWidths), 149 Alignments(TD.Alignments), 150 LayoutMap(0) 151 { } 152 153 ~TargetData(); // Not virtual, do not subclass this class 154 155 /// Target endianness... isLittleEndian()156 bool isLittleEndian() const { return LittleEndian; } isBigEndian()157 bool isBigEndian() const { return !LittleEndian; } 158 159 /// getStringRepresentation - Return the string representation of the 160 /// TargetData. This representation is in the same format accepted by the 161 /// string constructor above. 162 std::string getStringRepresentation() const; 163 164 /// isLegalInteger - This function returns true if the specified type is 165 /// known to be a native integer type supported by the CPU. For example, 166 /// i64 is not native on most 32-bit CPUs and i37 is not native on any known 167 /// one. This returns false if the integer width is not legal. 168 /// 169 /// The width is specified in bits. 170 /// isLegalInteger(unsigned Width)171 bool isLegalInteger(unsigned Width) const { 172 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i) 173 if (LegalIntWidths[i] == Width) 174 return true; 175 return false; 176 } 177 isIllegalInteger(unsigned Width)178 bool isIllegalInteger(unsigned Width) const { 179 return !isLegalInteger(Width); 180 } 181 182 /// Returns true if the given alignment exceeds the natural stack alignment. exceedsNaturalStackAlignment(unsigned Align)183 bool exceedsNaturalStackAlignment(unsigned Align) const { 184 return (StackNaturalAlign != 0) && (Align > StackNaturalAlign); 185 } 186 187 /// fitsInLegalInteger - This function returns true if the specified type fits 188 /// in a native integer type supported by the CPU. For example, if the CPU 189 /// only supports i32 as a native integer type, then i27 fits in a legal 190 // integer type but i45 does not. fitsInLegalInteger(unsigned Width)191 bool fitsInLegalInteger(unsigned Width) const { 192 for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i) 193 if (Width <= LegalIntWidths[i]) 194 return true; 195 return false; 196 } 197 198 /// Target pointer alignment getPointerABIAlignment()199 unsigned getPointerABIAlignment() const { return PointerABIAlign; } 200 /// Return target's alignment for stack-based pointers getPointerPrefAlignment()201 unsigned getPointerPrefAlignment() const { return PointerPrefAlign; } 202 /// Target pointer size getPointerSize()203 unsigned getPointerSize() const { return PointerMemSize; } 204 /// Target pointer size, in bits getPointerSizeInBits()205 unsigned getPointerSizeInBits() const { return 8*PointerMemSize; } 206 207 /// Size examples: 208 /// 209 /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*] 210 /// ---- ---------- --------------- --------------- 211 /// i1 1 8 8 212 /// i8 8 8 8 213 /// i19 19 24 32 214 /// i32 32 32 32 215 /// i100 100 104 128 216 /// i128 128 128 128 217 /// Float 32 32 32 218 /// Double 64 64 64 219 /// X86_FP80 80 80 96 220 /// 221 /// [*] The alloc size depends on the alignment, and thus on the target. 222 /// These values are for x86-32 linux. 223 224 /// getTypeSizeInBits - Return the number of bits necessary to hold the 225 /// specified type. For example, returns 36 for i36 and 80 for x86_fp80. 226 uint64_t getTypeSizeInBits(Type* Ty) const; 227 228 /// getTypeStoreSize - Return the maximum number of bytes that may be 229 /// overwritten by storing the specified type. For example, returns 5 230 /// for i36 and 10 for x86_fp80. getTypeStoreSize(Type * Ty)231 uint64_t getTypeStoreSize(Type *Ty) const { 232 return (getTypeSizeInBits(Ty)+7)/8; 233 } 234 235 /// getTypeStoreSizeInBits - Return the maximum number of bits that may be 236 /// overwritten by storing the specified type; always a multiple of 8. For 237 /// example, returns 40 for i36 and 80 for x86_fp80. getTypeStoreSizeInBits(Type * Ty)238 uint64_t getTypeStoreSizeInBits(Type *Ty) const { 239 return 8*getTypeStoreSize(Ty); 240 } 241 242 /// getTypeAllocSize - Return the offset in bytes between successive objects 243 /// of the specified type, including alignment padding. This is the amount 244 /// that alloca reserves for this type. For example, returns 12 or 16 for 245 /// x86_fp80, depending on alignment. getTypeAllocSize(Type * Ty)246 uint64_t getTypeAllocSize(Type* Ty) const { 247 // Round up to the next alignment boundary. 248 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty)); 249 } 250 251 /// getTypeAllocSizeInBits - Return the offset in bits between successive 252 /// objects of the specified type, including alignment padding; always a 253 /// multiple of 8. This is the amount that alloca reserves for this type. 254 /// For example, returns 96 or 128 for x86_fp80, depending on alignment. getTypeAllocSizeInBits(Type * Ty)255 uint64_t getTypeAllocSizeInBits(Type* Ty) const { 256 return 8*getTypeAllocSize(Ty); 257 } 258 259 /// getABITypeAlignment - Return the minimum ABI-required alignment for the 260 /// specified type. 261 unsigned getABITypeAlignment(Type *Ty) const; 262 263 /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for 264 /// an integer type of the specified bitwidth. 265 unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const; 266 267 268 /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment 269 /// for the specified type when it is part of a call frame. 270 unsigned getCallFrameTypeAlignment(Type *Ty) const; 271 272 273 /// getPrefTypeAlignment - Return the preferred stack/global alignment for 274 /// the specified type. This is always at least as good as the ABI alignment. 275 unsigned getPrefTypeAlignment(Type *Ty) const; 276 277 /// getPreferredTypeAlignmentShift - Return the preferred alignment for the 278 /// specified type, returned as log2 of the value (a shift amount). 279 /// 280 unsigned getPreferredTypeAlignmentShift(Type *Ty) const; 281 282 /// getIntPtrType - Return an unsigned integer type that is the same size or 283 /// greater to the host pointer size. 284 /// 285 IntegerType *getIntPtrType(LLVMContext &C) const; 286 287 /// getIndexedOffset - return the offset from the beginning of the type for 288 /// the specified indices. This is used to implement getelementptr. 289 /// 290 uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const; 291 292 /// getStructLayout - Return a StructLayout object, indicating the alignment 293 /// of the struct, its size, and the offsets of its fields. Note that this 294 /// information is lazily cached. 295 const StructLayout *getStructLayout(StructType *Ty) const; 296 297 /// getPreferredAlignment - Return the preferred alignment of the specified 298 /// global. This includes an explicitly requested alignment (if the global 299 /// has one). 300 unsigned getPreferredAlignment(const GlobalVariable *GV) const; 301 302 /// getPreferredAlignmentLog - Return the preferred alignment of the 303 /// specified global, returned in log form. This includes an explicitly 304 /// requested alignment (if the global has one). 305 unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const; 306 307 /// RoundUpAlignment - Round the specified value up to the next alignment 308 /// boundary specified by Alignment. For example, 7 rounded up to an 309 /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4 310 /// is 8 because it is already aligned. 311 template <typename UIntTy> RoundUpAlignment(UIntTy Val,unsigned Alignment)312 static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) { 313 assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!"); 314 return (Val + (Alignment-1)) & ~UIntTy(Alignment-1); 315 } 316 317 static char ID; // Pass identification, replacement for typeid 318 }; 319 320 /// StructLayout - used to lazily calculate structure layout information for a 321 /// target machine, based on the TargetData structure. 322 /// 323 class StructLayout { 324 uint64_t StructSize; 325 unsigned StructAlignment; 326 unsigned NumElements; 327 uint64_t MemberOffsets[1]; // variable sized array! 328 public: 329 getSizeInBytes()330 uint64_t getSizeInBytes() const { 331 return StructSize; 332 } 333 getSizeInBits()334 uint64_t getSizeInBits() const { 335 return 8*StructSize; 336 } 337 getAlignment()338 unsigned getAlignment() const { 339 return StructAlignment; 340 } 341 342 /// getElementContainingOffset - Given a valid byte offset into the structure, 343 /// return the structure index that contains it. 344 /// 345 unsigned getElementContainingOffset(uint64_t Offset) const; 346 getElementOffset(unsigned Idx)347 uint64_t getElementOffset(unsigned Idx) const { 348 assert(Idx < NumElements && "Invalid element idx!"); 349 return MemberOffsets[Idx]; 350 } 351 getElementOffsetInBits(unsigned Idx)352 uint64_t getElementOffsetInBits(unsigned Idx) const { 353 return getElementOffset(Idx)*8; 354 } 355 356 private: 357 friend class TargetData; // Only TargetData can create this class 358 StructLayout(StructType *ST, const TargetData &TD); 359 }; 360 361 } // End llvm namespace 362 363 #endif 364