include/llvm/BinaryFormat/Wasm.h

   1 //===- Wasm.h - Wasm object file format -------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file defines manifest constants for the wasm object file format.
  10 // See: https://github.com/WebAssembly/design/blob/master/BinaryEncoding.md
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_BINARYFORMAT_WASM_H
  15 #define LLVM_BINARYFORMAT_WASM_H
  16
  17 #include "llvm/ADT/ArrayRef.h"
  18 #include "llvm/ADT/SmallVector.h"
  19
  20 namespace llvm {
  21 namespace wasm {
  22
  23 // Object file magic string.
  24 const char WasmMagic[] = {'\0', 'a', 's', 'm'};
  25 // Wasm binary format version
  26 const uint32_t WasmVersion = 0x1;
  27 // Wasm linking metadata version
  28 const uint32_t WasmMetadataVersion = 0x2;
  29 // Wasm uses a 64k page size
  30 const uint32_t WasmPageSize = 65536;
  31
  32 struct WasmObjectHeader {
  33   StringRef Magic;
  34   uint32_t Version;
  35 };
  36
  37 struct WasmDylinkInfo {
  38   uint32_t MemorySize; // Memory size in bytes
  39   uint32_t MemoryAlignment;  // P2 alignment of memory
  40   uint32_t TableSize;  // Table size in elements
  41   uint32_t TableAlignment;  // P2 alignment of table
  42   std::vector<StringRef> Needed; // Shared library depenedencies
  43 };
  44
  45 struct WasmProducerInfo {
  46   std::vector<std::pair<std::string, std::string>> Languages;
  47   std::vector<std::pair<std::string, std::string>> Tools;
  48   std::vector<std::pair<std::string, std::string>> SDKs;
  49 };
  50
  51 struct WasmFeatureEntry {
  52   uint8_t Prefix;
  53   std::string Name;
  54 };
  55
  56 struct WasmExport {
  57   StringRef Name;
  58   uint8_t Kind;
  59   uint32_t Index;
  60 };
  61
  62 struct WasmLimits {
  63   uint8_t Flags;
  64   uint32_t Initial;
  65   uint32_t Maximum;
  66 };
  67
  68 struct WasmTable {
  69   uint8_t ElemType;
  70   WasmLimits Limits;
  71 };
  72
  73 struct WasmInitExpr {
  74   uint8_t Opcode;
  75   union {
  76     int32_t Int32;
  77     int64_t Int64;
  78     int32_t Float32;
  79     int64_t Float64;
  80     uint32_t Global;
  81   } Value;
  82 };
  83
  84 struct WasmGlobalType {
  85   uint8_t Type;
  86   bool Mutable;
  87 };
  88
  89 struct WasmGlobal {
  90   uint32_t Index;
  91   WasmGlobalType Type;
  92   WasmInitExpr InitExpr;
  93   StringRef SymbolName; // from the "linking" section
  94 };
  95
  96 struct WasmEventType {
  97   // Kind of event. Currently only WASM_EVENT_ATTRIBUTE_EXCEPTION is possible.
  98   uint32_t Attribute;
  99   uint32_t SigIndex;
 100 };
 101
 102 struct WasmEvent {
 103   uint32_t Index;
 104   WasmEventType Type;
 105   StringRef SymbolName; // from the "linking" section
 106 };
 107
 108 struct WasmImport {
 109   StringRef Module;
 110   StringRef Field;
 111   uint8_t Kind;
 112   union {
 113     uint32_t SigIndex;
 114     WasmGlobalType Global;
 115     WasmTable Table;
 116     WasmLimits Memory;
 117     WasmEventType Event;
 118   };
 119 };
 120
 121 struct WasmLocalDecl {
 122   uint8_t Type;
 123   uint32_t Count;
 124 };
 125
 126 struct WasmFunction {
 127   uint32_t Index;
 128   std::vector<WasmLocalDecl> Locals;
 129   ArrayRef<uint8_t> Body;
 130   uint32_t CodeSectionOffset;
 131   uint32_t Size;
 132   uint32_t CodeOffset;  // start of Locals and Body
 133   StringRef SymbolName; // from the "linking" section
 134   StringRef DebugName;  // from the "name" section
 135   uint32_t Comdat;      // from the "comdat info" section
 136 };
 137
 138 struct WasmDataSegment {
 139   uint32_t InitFlags;
 140   uint32_t MemoryIndex; // present if InitFlags & WASM_SEGMENT_HAS_MEMINDEX
 141   WasmInitExpr Offset; // present if InitFlags & WASM_SEGMENT_IS_PASSIVE == 0
 142   ArrayRef<uint8_t> Content;
 143   StringRef Name; // from the "segment info" section
 144   uint32_t Alignment;
 145   uint32_t LinkerFlags;
 146   uint32_t Comdat; // from the "comdat info" section
 147 };
 148
 149 struct WasmElemSegment {
 150   uint32_t TableIndex;
 151   WasmInitExpr Offset;
 152   std::vector<uint32_t> Functions;
 153 };
 154
 155 // Represents the location of a Wasm data symbol within a WasmDataSegment, as
 156 // the index of the segment, and the offset and size within the segment.
 157 struct WasmDataReference {
 158   uint32_t Segment;
 159   uint32_t Offset;
 160   uint32_t Size;
 161 };
 162
 163 struct WasmRelocation {
 164   uint8_t Type;    // The type of the relocation.
 165   uint32_t Index;  // Index into either symbol or type index space.
 166   uint64_t Offset; // Offset from the start of the section.
 167   int64_t Addend;  // A value to add to the symbol.
 168 };
 169
 170 struct WasmInitFunc {
 171   uint32_t Priority;
 172   uint32_t Symbol;
 173 };
 174
 175 struct WasmSymbolInfo {
 176   StringRef Name;
 177   uint8_t Kind;
 178   uint32_t Flags;
 179   StringRef ImportModule; // For undefined symbols the module of the import
 180   StringRef ImportName;   // For undefined symbols the name of the import
 181   union {
 182     // For function or global symbols, the index in function or global index
 183     // space.
 184     uint32_t ElementIndex;
 185     // For a data symbols, the address of the data relative to segment.
 186     WasmDataReference DataRef;
 187   };
 188 };
 189
 190 struct WasmFunctionName {
 191   uint32_t Index;
 192   StringRef Name;
 193 };
 194
 195 struct WasmLinkingData {
 196   uint32_t Version;
 197   std::vector<WasmInitFunc> InitFunctions;
 198   std::vector<StringRef> Comdats;
 199   std::vector<WasmSymbolInfo> SymbolTable;
 200 };
 201
 202 enum : unsigned {
 203   WASM_SEC_CUSTOM = 0,     // Custom / User-defined section
 204   WASM_SEC_TYPE = 1,       // Function signature declarations
 205   WASM_SEC_IMPORT = 2,     // Import declarations
 206   WASM_SEC_FUNCTION = 3,   // Function declarations
 207   WASM_SEC_TABLE = 4,      // Indirect function table and other tables
 208   WASM_SEC_MEMORY = 5,     // Memory attributes
 209   WASM_SEC_GLOBAL = 6,     // Global declarations
 210   WASM_SEC_EXPORT = 7,     // Exports
 211   WASM_SEC_START = 8,      // Start function declaration
 212   WASM_SEC_ELEM = 9,       // Elements section
 213   WASM_SEC_CODE = 10,      // Function bodies (code)
 214   WASM_SEC_DATA = 11,      // Data segments
 215   WASM_SEC_DATACOUNT = 12, // Data segment count
 216   WASM_SEC_EVENT = 13      // Event declarations
 217 };
 218
 219 // Type immediate encodings used in various contexts.
 220 enum : unsigned {
 221   WASM_TYPE_I32 = 0x7F,
 222   WASM_TYPE_I64 = 0x7E,
 223   WASM_TYPE_F32 = 0x7D,
 224   WASM_TYPE_F64 = 0x7C,
 225   WASM_TYPE_V128 = 0x7B,
 226   WASM_TYPE_FUNCREF = 0x70,
 227   WASM_TYPE_EXCEPT_REF = 0x68,
 228   WASM_TYPE_FUNC = 0x60,
 229   WASM_TYPE_NORESULT = 0x40, // for blocks with no result values
 230 };
 231
 232 // Kinds of externals (for imports and exports).
 233 enum : unsigned {
 234   WASM_EXTERNAL_FUNCTION = 0x0,
 235   WASM_EXTERNAL_TABLE = 0x1,
 236   WASM_EXTERNAL_MEMORY = 0x2,
 237   WASM_EXTERNAL_GLOBAL = 0x3,
 238   WASM_EXTERNAL_EVENT = 0x4,
 239 };
 240
 241 // Opcodes used in initializer expressions.
 242 enum : unsigned {
 243   WASM_OPCODE_END = 0x0b,
 244   WASM_OPCODE_CALL = 0x10,
 245   WASM_OPCODE_GLOBAL_GET = 0x23,
 246   WASM_OPCODE_I32_STORE = 0x36,
 247   WASM_OPCODE_I32_CONST = 0x41,
 248   WASM_OPCODE_I64_CONST = 0x42,
 249   WASM_OPCODE_F32_CONST = 0x43,
 250   WASM_OPCODE_F64_CONST = 0x44,
 251   WASM_OPCODE_I32_ADD = 0x6a,
 252   WASM_OPCODE_MISC_PREFIX = 0xfc,
 253   WASM_OPCODE_MEMORY_INIT = 0x08,
 254   WASM_OPCODE_DATA_DROP = 0x09,
 255 };
 256
 257 enum : unsigned {
 258   WASM_LIMITS_FLAG_HAS_MAX = 0x1,
 259   WASM_LIMITS_FLAG_IS_SHARED = 0x2,
 260 };
 261
 262 enum : unsigned {
 263   WASM_SEGMENT_IS_PASSIVE = 0x01,
 264   WASM_SEGMENT_HAS_MEMINDEX = 0x02,
 265 };
 266
 267 // Feature policy prefixes used in the custom "target_features" section
 268 enum : uint8_t {
 269   WASM_FEATURE_PREFIX_USED = '+',
 270   WASM_FEATURE_PREFIX_REQUIRED = '=',
 271   WASM_FEATURE_PREFIX_DISALLOWED = '-',
 272 };
 273
 274 // Kind codes used in the custom "name" section
 275 enum : unsigned {
 276   WASM_NAMES_FUNCTION = 0x1,
 277   WASM_NAMES_LOCAL = 0x2,
 278 };
 279
 280 // Kind codes used in the custom "linking" section
 281 enum : unsigned {
 282   WASM_SEGMENT_INFO = 0x5,
 283   WASM_INIT_FUNCS = 0x6,
 284   WASM_COMDAT_INFO = 0x7,
 285   WASM_SYMBOL_TABLE = 0x8,
 286 };
 287
 288 // Kind codes used in the custom "linking" section in the WASM_COMDAT_INFO
 289 enum : unsigned {
 290   WASM_COMDAT_DATA = 0x0,
 291   WASM_COMDAT_FUNCTION = 0x1,
 292 };
 293
 294 // Kind codes used in the custom "linking" section in the WASM_SYMBOL_TABLE
 295 enum WasmSymbolType : unsigned {
 296   WASM_SYMBOL_TYPE_FUNCTION = 0x0,
 297   WASM_SYMBOL_TYPE_DATA = 0x1,
 298   WASM_SYMBOL_TYPE_GLOBAL = 0x2,
 299   WASM_SYMBOL_TYPE_SECTION = 0x3,
 300   WASM_SYMBOL_TYPE_EVENT = 0x4,
 301 };
 302
 303 // Kinds of event attributes.
 304 enum WasmEventAttribute : unsigned {
 305   WASM_EVENT_ATTRIBUTE_EXCEPTION = 0x0,
 306 };
 307
 308 const unsigned WASM_SYMBOL_BINDING_MASK = 0x3;
 309 const unsigned WASM_SYMBOL_VISIBILITY_MASK = 0xc;
 310
 311 const unsigned WASM_SYMBOL_BINDING_GLOBAL = 0x0;
 312 const unsigned WASM_SYMBOL_BINDING_WEAK = 0x1;
 313 const unsigned WASM_SYMBOL_BINDING_LOCAL = 0x2;
 314 const unsigned WASM_SYMBOL_VISIBILITY_DEFAULT = 0x0;
 315 const unsigned WASM_SYMBOL_VISIBILITY_HIDDEN = 0x4;
 316 const unsigned WASM_SYMBOL_UNDEFINED = 0x10;
 317 const unsigned WASM_SYMBOL_EXPORTED = 0x20;
 318 const unsigned WASM_SYMBOL_EXPLICIT_NAME = 0x40;
 319
 320 #define WASM_RELOC(name, value) name = value,
 321
 322 enum : unsigned {
 323 #include "WasmRelocs.def"
 324 };
 325
 326 #undef WASM_RELOC
 327
 328 // Subset of types that a value can have
 329 enum class ValType {
 330   I32 = WASM_TYPE_I32,
 331   I64 = WASM_TYPE_I64,
 332   F32 = WASM_TYPE_F32,
 333   F64 = WASM_TYPE_F64,
 334   V128 = WASM_TYPE_V128,
 335   EXCEPT_REF = WASM_TYPE_EXCEPT_REF,
 336 };
 337
 338 struct WasmSignature {
 339   SmallVector<ValType, 1> Returns;
 340   SmallVector<ValType, 4> Params;
 341   // Support empty and tombstone instances, needed by DenseMap.
 342   enum { Plain, Empty, Tombstone } State = Plain;
 343
 344   WasmSignature(SmallVector<ValType, 1> &&InReturns,
 345                 SmallVector<ValType, 4> &&InParams)
 346       : Returns(InReturns), Params(InParams) {}
 347   WasmSignature() = default;
 348 };
 349
 350 // Useful comparison operators
 351 inline bool operator==(const WasmSignature &LHS, const WasmSignature &RHS) {
 352   return LHS.State == RHS.State && LHS.Returns == RHS.Returns &&
 353          LHS.Params == RHS.Params;
 354 }
 355
 356 inline bool operator!=(const WasmSignature &LHS, const WasmSignature &RHS) {
 357   return !(LHS == RHS);
 358 }
 359
 360 inline bool operator==(const WasmGlobalType &LHS, const WasmGlobalType &RHS) {
 361   return LHS.Type == RHS.Type && LHS.Mutable == RHS.Mutable;
 362 }
 363
 364 inline bool operator!=(const WasmGlobalType &LHS, const WasmGlobalType &RHS) {
 365   return !(LHS == RHS);
 366 }
 367
 368 std::string toString(WasmSymbolType type);
 369 std::string relocTypetoString(uint32_t type);
 370 bool relocTypeHasAddend(uint32_t type);
 371
 372 } // end namespace wasm
 373 } // end namespace llvm
 374
 375 #endif