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